JP2008249903A - Protective film for polarizing plate, method for producing the same, polarizing plate, and image display device - Google Patents

Abstract

Disclosed is a polarizing plate protective film having low moisture permeability and high adhesion, a polarizing plate using the same, and an image display device capable of maintaining the quality of a display image for a long time by using the polarizing plate. Offer.
A coating composition for a coating layer containing at least an organic solvent is coated on a transparent substrate that swells or dissolves with the organic solvent, and then the organic solvent is dried to coat the transparent substrate. A protective film for a polarizing plate produced by a method for manufacturing a protective film for a polarizing plate comprising at least a drying step for forming a layer, wherein the residual amount of the organic solvent is 1.0 g / m ² or less. A polarizing plate protective film.
[Selection figure] None

Description

  The present invention relates to a protective film for a polarizing plate having a coating layer on a transparent substrate film, a method for producing the same, a polarizing plate, and an image display device.

  Recently, as an example of image display, a liquid crystal display device (hereinafter sometimes referred to as an LCD) has been widely used instead of a CRT because it is thin, lightweight, and has low power consumption. . The demand for polarizing plates is rapidly increasing with the spread of LCDs. The field of use is also expanding from small products such as conventional calculators and watches to large products such as automotive instruments, PC monitors, and televisions.

  Since the display device is often in use for a long time at all times, the polarizing plate has long-term durability so that the image quality of the LCD is not deteriorated even in long-term use in an environment having temperature and humidity changes. It has come to be required.

  In the polarizing plate, a polarizing plate protective film (hereinafter sometimes referred to as a protective layer) is bonded to both sides or one side of a polarizing film having polarizing ability through an adhesive layer. As a material for the polarizing film, polyvinyl alcohol (hereinafter sometimes referred to as PVA) is mainly used. After the PVA film is uniaxially stretched, it is dyed with iodine or a dichroic dye or dyed. The polarizing film is formed by stretching and further crosslinking with a boron compound. As the protective layer, cellulose triacetate (hereinafter sometimes referred to as TAC) is mainly used because it is optically transparent and has low birefringence and a smooth surface.

  However, when cellulose triacetate is used as a protective layer, display image unevenness may occur due to changes in the size of the polarizing film due to changes in temperature and humidity during long-term use, and improvements are desired.

As a technique for solving these problems, it has been reported that a sheet made of a norbornene resin is useful as a protective film (protective layer) for a polarizing film (see Patent Document 1).
However, a sheet made of norbornene-based resin has a sufficiently low moisture permeability and is difficult to be subjected to a change in humidity, but has a problem that adhesiveness with a polarizing film is insufficient and productivity is low.

  Moreover, it has been reported that the wet heat property of a polarizing plate improves by using the protective film which provided the layer containing a vinylidene chloride copolymer on the surface of a cellulose triacetate film (refer patent document 2, 3). .

  However, in Patent Documents 2 and 3, there is no description of moisture permeability, and the material and film thickness described in those patents do not necessarily provide a sufficient moisture permeability reduction effect intended in the present invention, and sufficient adhesion. There is a problem that cannot be obtained.

  Further, since the layer containing the vinylidene chloride copolymer has a low surface hardness, it is preferable to carry out a hard coat treatment. However, the description regarding the hard coat is not sufficient, and a hard coat layer is provided on the vinylidene chloride layer. Issues such as surface condition, adhesion, and performance change remain.

In other patent documents, it is reported that water vapor permeability decreases by using a protective film provided with a hydrophobic compound (see Patent Document 4).
In Patent Document 4, it is reported that a liquid crystal polymer layer containing a thermotropic liquid crystal polymer is provided, but there is no report that it is formed on a cellulose triacetate film, and it is a laminated structure with other layers and is not applied but melted. In terms of being formed by film formation, it is not suitable for use as a protective film for polarizing plates.

JP-A-10-101907 JP-A-62-161103 JP 2001-215331 A JP 2000-094613 A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, the present invention provides a polarizing plate protective film having low moisture permeability, high adhesion, and high light resistance, a polarizing plate using the polarizing plate, and a polarizing plate using the polarizing plate. An object of the present invention is to provide an image display device that can be maintained.

  As a result of intensive studies, the present inventors applied a coating composition containing a resin component capable of expressing low moisture permeability and an organic solvent to form a coating layer having low moisture permeability made of cellulose acylates. When forming a protective film for a polarizing plate by forming it on one side of a transparent substrate film, the barrier property of the coating layer is manifested by the drying process of drying the coating composition, and thus exhibits a preferable low moisture permeability. For this purpose, it has been found that the above problem can be solved by selecting a suitable solvent type and drying conditions and controlling the amount of residual solvent.

This invention is based on the said knowledge by the present inventors, and the means for solving the said subject are as follows. That is,
<1> After coating a coating composition for a coating layer containing at least an organic solvent on a transparent base material that swells or dissolves with the organic solvent, the organic solvent is dried to reduce the low permeability on the transparent base material. A protective film for a polarizing plate produced by a method for producing a protective film for a polarizing plate comprising at least a drying step for forming a wet coating layer, wherein the residual amount of the organic solvent is 1.0 g / m ² or less. It is the protective film for polarizing plates characterized by these.
<2> The polarizing plate protective film according to <1>, wherein the residual amount of the organic solvent is 0.5 g / m ² or less.
<3> The protective film for a polarizing plate according to any one of <1> to <2>, wherein moisture permeability at 60 ° C. and 95% relative humidity is 700 g / m ² · day or less.
<4> The polarizing plate protective film according to any one of <1> to <3>, wherein the transparent substrate is made of cellulose acylates.
<5> The polarizing plate protective film according to <4>, wherein the cellulose acylates are at least one of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.
<6> The protective film for a polarizing plate according to any one of <1> to <5>, wherein the film thickness of the transparent substrate is 30 μm to 120 μm.
<7> The polarizing plate protective film according to any one of <1> to <6>, wherein the coating layer has a thickness of 0.2 μm to 10 μm.
<8> The coating composition for a coating layer is the protective film for a polarizing plate according to any one of <1> to <7>, including a polymer resin.
<9> The protective film for a polarizing plate according to <8>, wherein the polymer resin includes any one of a resin including a repeating unit derived from a chlorine-containing vinyl monomer, a fluorine-based resin, and an olefin-based resin. is there.
<10> The <1> to <9>, wherein the second layer, which is at least one of a layer having a hard coat property and a layer having an antireflection layer, is formed on the coating layer. It is a protective film for polarizing plates.
<11> The protective film for a polarizing plate according to any one of <1> to <10>, wherein the coating layer coating composition has at least one of a light stabilizer and a heat stabilizer.

<12> A coating step of coating a coating composition for a coating layer containing at least an organic solvent on a transparent substrate that swells or dissolves with the organic solvent;
A drying step of drying the organic solvent so that a residual amount of the organic solvent is 1.0 g / m ² or less to form a low moisture-permeable coating layer on the transparent substrate. It is a manufacturing method of the protective film for polarizing plates.
<13> The method for producing a protective film for a polarizing plate according to <12>, wherein an organic solvent component having a boiling point of 100 ° C. or less is contained by 30% by mass or more of the organic solvent.
<14> The organic solvent is composed of at least two kinds of organic solvent components, and the organic solvent component that cannot swell or dissolve the transparent substrate and has a boiling point of 100 ° C. to 200 ° C. is 5% by mass of the organic solvent. The method for producing a protective film for a polarizing plate according to any one of <12> to <13>, wherein the content is less than 70% by mass.
<15> The drying step includes the first drying step of evaporating 50% or more of the organic solvent within 1 to 15 seconds after the coating layer coating composition is applied on the transparent substrate. It is a manufacturing method of the protective film for polarizing plates in any one of <11> to <13>.
<16> The drying step includes a first drying step of drying at a drying temperature of 70 ° C. or lower until 50% or more of the organic solvent evaporates, and a drying step of 70 ° C. or higher and a drying temperature of 150 ° C. or lower thereafter. It is a manufacturing method of the protective film for polarizing plates as described in said <15> including 2 drying processes.
<17> The above-mentioned <12> including the second layer forming step of forming the second layer by drying the solvent after applying the coating composition for the second layer containing at least the organic solvent on the coating layer. To <16>. The method for producing a protective film for a polarizing plate according to any one of <16>.

  <18> A polarizing plate protective film produced by the method for producing a polarizing plate protective film according to any one of <12> to <17>.

  <19> A polarizing film, and the polarizing plate protective film according to any one of <1> to <11> and <18> provided on at least one surface of the polarizing film, It is a polarizing plate.

  <20> An image display device comprising the polarizing plate according to <19>.

  According to the present invention, a polarizing plate protective film having low moisture permeability, high adhesion, and high light resistance, a polarizing plate using the polarizing plate, and the polarizing plate can be used to improve the quality of display images over a long period of time. An image display device that can be maintained can be provided.

  Hereinafter, the protective film, polarizing plate, and image display device of the present invention will be described in detail, but the protective film for polarizing plate, polarizing plate, and image display device of the present invention are not limited to the forms described below. .

(Protective film for polarizing plate)
1A to 1C are cross-sectional views showing a configuration in one embodiment of a protective film for a polarizing plate of the present invention.
As shown in FIG. 1A, a protective film 1 for polarizing plate of the present invention includes a transparent substrate film (hereinafter sometimes referred to as a transparent substrate) 2 and a coating layer having low moisture permeability (hereinafter referred to as a barrier layer). 3).
As shown in FIG. 1B, a second layer 4 may be provided on the covering layer 3. There is no restriction | limiting in particular as this 2nd layer 4, According to the objective, it selects suitably, The layer (henceforth a hard-coat layer), antireflection layer, or coating layer 3 which has a hard-coat property is what Various functional layers such as coating layers made of different materials can be used. Among these, a layer having a hard coat property is preferable, and FIG. 1B shows a case where a layer having a hard coat property is used as the second layer 4.
It is also preferable to add internal scattering properties and surface scattering properties to the layer having hard coat properties.
In addition, it is also preferable to further provide an antireflection layer on the hard coat layer for the purpose of reducing the reflectance of the surface.

As shown in FIG. 1C, it is also preferable as another embodiment of the present invention to form a layer having hard coat properties on the opposite side of the coating layer 3. It is also preferable to add internal scattering properties and surface scattering properties to the layer having hard coat properties.
It is also preferable to further provide an antireflection layer on the hard coat layer 4 for the purpose of reducing the reflectance of the surface. It is also preferable to provide another layer on the coating layer 3.
In particular, it is also preferable to form an easy-adhesion layer as a layer in contact with the surface on the opposite side of the transparent support of the coating layer 3 or a layer in contact with the surface on the transparent support in order to have affinity with the film.

<Physical properties of protective film for polarizing plate>
<< moisture permeability >>
Next, the moisture permeability will be described in detail.
The measurement method of moisture permeability is "Polymer Physical Properties II" (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The film sample of 70 mmφ according to the present invention was conditioned at 60 ° C. and 95% RH for 24 hours, and the moisture permeability according to JIS Z-0208 was determined from the difference in mass before and after humidity adjustment. Using a cup, the moisture content per unit area (g / m ² ) was calculated from moisture permeability = mass after humidity adjustment−mass before humidity adjustment. The moisture permeability value was not corrected for a blank cup without a hygroscopic agent.
The moisture permeability of a commercially available cellulose acetate film measured by the above measurement method is generally 80 μm in thickness and 1,400 to 1,500 g / m ² · day under the above conditions.
The upper limit of the moisture permeability of the protective film for polarizing plate of the present invention at 60 ° C. and 95% relative humidity is difficult to measure with a single coating layer. If the coating layer is difficult to measure, the coating layer is made of a resin transparent substrate film (TD80UL made by Fuji Film). When formed at 60 ° C. and 95% relative humidity, the moisture permeability is about 1400 g / m ² · day), preferably 700 g / m ² · day or less, and 400 g / m ² · day or less. Is more preferably 250 or less, and particularly preferably 100 g / m ² · day or less. If the moisture permeability is higher than the above upper limit value, the effect of reducing the occurrence of unevenness in the display image due to the change in the size of the polarizing film due to the change in temperature and humidity during low-term use is low. The lower limit is not particularly limited, but is preferably 20 g / m ² · day or more, more preferably 30 g / m ² · day or more, from the viewpoint of productivity during polarizing plate processing.
Therefore, the moisture permeability of the polarizing plate protective film of the present invention is particularly preferably in the range of 30 to 250 g / m ² · day. Within this range, the performance (polarization degree, single plate transmittance) as a polarizing plate is not deteriorated, and unevenness of the display image is caused by changes in the size of the polarizing film due to changes in temperature and humidity during long-term use. Can be suppressed.
When it is difficult to measure the coating layer alone, the coating layer is formed on a transparent substrate film made of resin (TD80UL 60 ° C., Fuji Film, the moisture permeability at 95% relative humidity is about 1400 g / m ² · day). You may define with the calculated value of the moisture permeability (Pc) of the coating layer calculated | required from the relationship of the following Formula (1) from the moisture permeability at the time of doing. Moisture permeability of the coating layer is preferably less than ² · day 1400 g / ^m, particularly preferably less than ² · day 500g / ^m, 300g / ^m more preferably less than ² · day or less, and most preferably ^2-days 110g / ^m.

1 / Pb + 1 / Pc = 1 / Pall (Formula 1)
Pb: moisture permeability of transparent substrate film Pc: moisture permeability of coating layer Pall: moisture permeability when the coating layer is formed on a resin transparent substrate film

<< Residual amount of organic solvent >>
The said coating layer is formed through the drying process which dries the solvent, after apply | coating the coating composition containing an organic solvent on the transparent base material which swells or melt | dissolves with this organic solvent.
By using an organic solvent that swells or dissolves the transparent substrate, adhesion between the substrate and the coating layer can be ensured.
When water is used as a solvent without using an organic solvent, a substrate that swells or dissolves with water is not suitable as a substrate for a protective film for polarizing plates, and is not suitable for the present invention.
In addition, when forming a layer having a hard coat property on the coating layer, since the layer having a hard coat property is generally formed from a coating composition containing an organic solvent, in the coating layer formed using water as the solvent, It is not easy to take strong adhesion with the upper layer having hard coat properties, which is not preferable.

  The solvent that swells or dissolves the transparent substrate used in the present invention can be confirmed by deformation of the substrate after the transparent substrate is immersed in the solvent for one day. It can be seen that when a solvent that swells or dissolves the transparent substrate is used, the substrate is deformed into an indefinite shape and is clearly immersed in the solvent.

In the present invention, it is preferable that the residual solvent content of the polarizing plate protective film is 1 g / ^{m 2} or less, 0.7 g / ^m, more preferably less than ² · day, 0.5 g / ^{m 2} · day or less are particularly preferred. If the amount of residual solvent is too large, the moisture permeability and adhesiveness deteriorate, and problems such as deterioration in durability against light occur.
The residual solvent amount indicates the residual solvent amount immediately after the coating layer is applied and dried. Therefore, when a transparent substrate is unwound from a roll form, coated and dried, and then wound into a roll form to prepare a sample, the residual solvent amount immediately after being wound into the roll state may be used as a representative value. . Since the amount of residual solvent varies with storage time during storage, the sample after storage must naturally have a residual solvent amount within the scope of this patent.

<< Quantitative analysis of residual organic solvent in film >>
The determination of the organic solvent remaining in the film in the present invention is preferably carried out using gas chromatography (GC) equipped with a flame ionization detector (FID).
Hereinafter, the quantitative analysis of the organic solvent remaining in the film will be described in detail.
Examples of the GC device include a GC-2010 model manufactured by Shimadzu Corporation.
Moreover, about the column, DB-624 (length 60m, diameter 0.32mm, film thickness 1.8micrometer) by J & W company is mentioned, for example.
Preparation of a measurement sample is performed by first adding 1.5 g of a film sample to be measured to 40 g of a solvent for dissolving a transparent base material and a coating layer in a screw cap bottle, capping, and stirring at 60 rpm at room temperature for 12 hours. By doing so, the residual organic solvent in the sample is extracted into the solvent for dissolution, and a sample solution is prepared.
When a transparent substrate made of cellulose acylates is employed as the transparent substrate, it is particularly preferable to use n-methylpyrrolidone.
Thereafter, 0.5 g of the prepared sample solution is weighed and diluted by adding 2.5 g of n-methylpyrrolidone.
In the analysis, this solution was subjected to predetermined conditions (injector temperature 230 ° C., detector temperature 250 ° C., column temperature 80 ° C. → 4 ° C./min temperature increase → 230 ° C. 5 min hold, carrier gas He 90 KPa, split ratio 1 / Inject 1 μl into the GC device of 20).
And the area value of the detected peak is calculated | required by carrying out density | concentration conversion from the area value of the 3 inspection amount curve produced separately.
In the present invention, the residual amount of each solvent used in the above method was measured, and the total value was used as the residual amount.

<< Haze >>
The haze of the protective film for polarizing plate of the present invention is preferably 10% or less, more preferably 5 or less, still more preferably 2% or less, and most preferably 1.0% or less. If the haze is large, it is not preferable from the viewpoint of reducing the contrast of the displayed image and image blur. The ratio between the surface haze and the internal haze may be arbitrary, but since the surface haze can be reduced by forming the second layer on the upper layer of the coating layer, the internal haze is particularly preferably 2% or less, Most preferably, the internal haze is 1% or less. The internal haze can be obtained by measuring the haze in a state where the liquid having the same refractive index as that of the coating layer is sandwiched between the coating layer and the glass plate and the surface is not scattered.

<< Transparent light color >>
Moreover, it is preferable that the protective film for polarizing plates of this invention is substantially colorless. “Substantially colorless” means that the absolute values of a ^* and b ^* expressed in the L ^* , a ^* and b ^* color system are 3.0 or less. The absolute value is more preferably 2.5 or less, and particularly preferably 2 or less. Substantially colorless, it is preferable because the color tone is neutral gray when used as a polarizing plate, and troubles such as troubles in color display are not caused.

<< Curl >>
As for the protective film for polarizing plates in this invention, it is preferable that the value when curl is represented by the following numerical formula (1) is in the range of −15 to +15, more preferably −12 to +12. More preferably, it is −10 to +10. In this case, the measurement direction of the curl in the sample is measured in the conveyance direction of the base material in the case of application in a web form. In the following formula (1), R represents a radius of curvature (m).
Carl = 1 / R ... Formula (1)

  It is preferable that the curl value is in the above range and the curl is small. If it is in said range, a crack and film | membrane peeling will not occur by manufacture of a film which has a coating layer, a process, and handling in a market, and it is preferable. It is possible to reduce the curl within the above range and increase the surface hardness by setting the volume shrinkage ratio before and after curing to 15% or less. The curl is measured using the curl measurement template of Method A in “Measuring Method of Curling of Photographic Film” of JIS K-7619-1988. The measurement conditions are 25 ° C., humidity 60% RH, and humidity control time 10 hours. Here, “curl plus” means a curl in which the coating layer coating side of the film is inside the curve, and “minus” means a curl in which the coating side is outside the curve.

  The protective film for polarizing plate of the present invention has an absolute value of the difference between the curl values of 24 to 0, further 15 when the humidity is changed from 80% RH to 10% RH based on the curl measurement method. It is preferable to be in the range of ˜0, particularly 8˜0. This is a property related to handling properties, peeling, and cracking when a polarizing plate protective film is attached under various humidity conditions.

<< crack resistance >>
The cracking resistance of the protective film for polarizing plate of the present invention is preferably 30 mm or less, more preferably 25 mm or less, with a radius of curvature at which cracking occurs when the coating layer coating side is rolled outward. Most preferably, it is 20 mm or less. About the crack of an edge part, it is preferable that there is no crack or the length of a crack is less than 1 mm on average. This crack resistance is an important characteristic for preventing crack defects in handling such as coating, processing, cutting, and sticking of a film having a coating layer.

  In the coating layer of the protective film for polarizing plate of the present invention, additives such as a heat stabilizer, a light stabilizer and a lubricant can be used as necessary.

<< light resistance >>
Using a metering weather meter MV3000 manufactured by Suga Test Instruments Co., Ltd., irradiance 530 ± 25 W / m ² (wavelength 310 to 400 nm), test chamber temperature 40 ± 5 ° C., black panel temperature 60 ± 5 ° C., relative humidity 50 ± Under the condition of 10%, the light irradiation treatment was performed under the emphasis condition in which the sample attached on the SUS plate was irradiated with light for 1 hour.

In the present invention, the degree of change in appearance (color of transmitted light) was evaluated as a measure for measuring the light resistance of the polarizing plate protective film.
The inventors of the present invention quantitatively measure and display these as numerical values to be displayed by the following mathematical formula (2) (color difference ΔE ^* ab value in the CIE1976L ^* a ^* b ^* color space). ) Was found to be appropriate.
For example, if the transparency deteriorates (the transmittance decreases), ΔL ^* increases, and as a result, the transmitted light color change amount ΔE ^* ab value increases.
If the color of the transmitted light changes, Δa ^* and Δb ^* increase, and the transmitted light color change ΔE ^* ab value also increases. The correspondence between the transmitted light color change amount ΔE ^* ab value and the sensory evaluation result for the appearance change is almost as shown in Table 1 below. The color change amount indicates the degree of appearance change of the polarizing plate protective film, that is, the light resistance. It can be seen that this is an appropriate evaluation characteristic that reflects correctly.
The transmitted light color change ΔE ^* ab value is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.3 or less. By setting the transmitted light color change ΔE ^* ab value to 4.5 or less, high light resistance can be achieved.

ΔE ^* ab = [(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² ] ^1/2 Equation (2)
ΔL ^* = L1 ^* −L2 ^*
Δa ^* = a1 ^* −a2 ^*
Δb ^* = b1 ^* −b2 ^*
(In Formula (2), L1 ^* , a1 ^* , b1 ^* , L2 ^* , a2 ^* , and b2 ^* indicate the color of the transmitted light of the CIE standard light source C of the polarizing plate protective film, and CIE1976L ^* a ^* b ^{*. L *} value of the color space, but expresses ^{a *} value, and ^{b *} in value. in ^addition, L1 *, a1 ^*, and b1 ^* are, L polarizing plate protective film before carrying out the light resistance test ^* Value, a ^* value, and b ^* value, and L2 ^* , a2 ^* , and b2 ^* are the L ^* value, a ^* value, and b ^* of the polarizing plate protective film after the light resistance test was conducted ^. Represents the value.)

In the above mathematical formula (2), L1 ^* , a1 ^* , b1 ^* , L2 ^* , a2 ^* , and b2 ^* are values calculated in detail by the following method.

[Calculation of L1 ^* , a1 ^* , and b1 ^* ]
Using a spectrophotometer (UV-3150, manufactured by Shimadzu Corporation), the spectral transmittance is measured in a wavelength region of 380 to 780 nm.
Next, the obtained spectral transmittance data and the spectral distribution data of the CIE C standard light source are multiplied for each wavelength to obtain spectral transmitted light for the C light source.
CIE1976L ^* a ^* b ^* color space L ^* value, a ^* value, and b ^* value in the CIE standard light source C are calculated from the obtained spectral transmission light data under the standard light, and L1 ^* , a1 ^* , and Let b1 ^* .

[Calculation of L2 ^* , a2 ^* , and b2 ^* ]
Using a metering weather meter MV3000 manufactured by Suga Test Instruments Co., Ltd., irradiance 530 ± 25 W / m 2 (wavelength 310 to 400 nm), test chamber temperature 40 ± 5 ° C., black panel temperature 60 ± 5 ° C., relative humidity 50 ± 10 After performing the light irradiation treatment under the emphasis condition of irradiating the sample attached on the SUS plate with light for 1 hour under the condition of%, the same is performed using the spectrophotometer (UV-3150, manufactured by Shimadzu Corporation). The L ^* value, a ^* value, and b ^* value calculated from the values measured in the above are defined as L2 ^* , a2 ^* , and b2 ^* .

The mixed region formed after coating the coating layer is the solid content concentration of the coating layer coating solution, the solvent type, the solvent composition, the type of ionizing radiation curable compound, the additive, the type of transparent substrate film to which the coating layer is applied. It is affected by various conditions such as the coating amount of the coating layer coating solution, drying conditions, and curing conditions. In the present invention, the above conditions are not particularly limited as long as a mixed region is formed between the transparent base film and the coating layer and there is an effect of suppressing interference unevenness of the coating layer.
The layer thickness in the mixed region is preferably in the range of 0.01 to 2 μm, more preferably 0.02 to 1 μm, and still more preferably 0.05 to 0.5 μm. If the layer thickness in the mixed region is smaller than this range, the adhesiveness of the coating layer is not sufficient, and if it is larger than this range, the strength of the coating layer tends to decrease and the moisture permeability tends to increase. The thickness of the layer in the mixed region was photographed by cutting the cross section of the polarizing plate protective film using a microtome, observing in the reflected electron mode from the cross section using a scanning electron microscope (S-570, manufactured by Hitachi, Ltd.). The thickness of the layer in the mixed region can be obtained from the photograph. Moreover, when it is difficult to discriminate the mixed layer region from a photograph of a scanning electron microscope, it can be obtained from elemental analysis using TOF-SIMS of the cross section.

<Transparent substrate film>
As the transparent base film used in the present invention, a cellulose acylate film is used because it is optically uniform, has a smooth surface, and has good secondary workability in producing a polarizing plate. It is preferable.
The cellulose acylate used in the present invention is an aliphatic carboxylic acid ester having about 2 to 22 carbon atoms or an aromatic carboxylic acid ester, and particularly preferably a lower fatty acid ester of cellulose.
Here, the lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms, such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate phthalate, etc. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate as described in Japanese Patent No. 45804, JP-A-8-231761, and US Pat. No. 2319052 are used.
It is also preferable to use esters of aromatic carboxylic acids and cellulose described in JP-A Nos. 2002-179701, 2002-265639, and 2002-265638. Among the above description, the lower fatty acid esters of cellulose that are particularly preferably used are cellulose triacetate and cellulose acetate propionate described later. These cellulose esters can also be mixed and used.

The degree of substitution (DS) of cellulose acylate means the ratio of acylation of three hydroxyl groups present in the cellulose structural unit (glucose having β1 → 4 glycosidic bonds).
The degree of substitution can be calculated by measuring the amount of bound fatty acid per unit mass of cellulose. The measurement method is carried out according to ASTM-D817-91.
The cellulose acylate of the present invention balances the humidity dependence of the retardation and the dimensional stability by appropriately balancing the hydrophobicity of the acyl group and the hydrophilicity of the hydroxyl group.
That is, if the alkyl chain in the acyl group is too short on average and / or the hydroxyl group ratio is too high, the humidity dependency of retardation becomes large.
On the other hand, if the alkyl chain in the acyl group is too long on average and / or the hydroxyl group ratio is too high, the Tg decreases and the dimensional stability deteriorates.
Therefore, the cellulose triacetate preferably used in the present invention preferably has a degree of acetylation of 2.83 or more and 2.91 or less and no other acyl group having 3 or more carbon atoms. The degree of acetylation is more preferably 2.84 or more and 2.89 or less.

  In addition, cellulose ester other than cellulose triacetate has an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of acetyl group is X, and the substitution degree of propionyl group is Y, the following formula ( It is a cellulose ester that satisfies both a) and formula (b) at the same time.

2.6 ≦ X + Y ≦ 2.9 Equation (a)
0 ≦ X ≦ 2.5 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Formula (b)

  Here, among cellulose esters satisfying the above formulas (a) and (b) at the same time, cellulose acetate propionate (total acyl group substitution degree) of 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 = X + Y) is preferred. The portion not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods.

  30-120 micrometers is preferable and, as for the thickness of a transparent base film, 40-80 micrometers is more preferable. If the thickness of the base film is equal to or greater than the lower limit, problems such as a decrease in film strength are unlikely to occur. If the thickness is equal to or less than the upper limit, the mass increases excessively, particularly for large televisions of 20 inches or more. It is preferable because adverse effects such as disadvantages are less likely to occur.

[Ultraviolet absorber]
It is preferable that two or more kinds of ultraviolet absorbers represented by the following general formula (1) are contained in any of the transparent substrate film, moisture-proof layer, undercoat layer, and hard coat layer of the present invention.
In the following general formula (1), R ¹ , R ² , R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or a monovalent organic group, and at least of R ¹ , R ² and R ³ One represents an unsubstituted branched or straight chain alkyl group having 4 to 20 carbon atoms, and R ¹ , R ² and R ³ are different from each other.
In addition, the average value (hereinafter referred to as average log P) of octanol / water partition coefficient (hereinafter referred to as log P) represented by the following mathematical formula (c) relating to the ultraviolet absorber and the acylation degree DS of cellulose acylate are represented by the following mathematical formula (d It is more preferable that a cellulose acylate film satisfying the relationship (2) is used as the transparent substrate film.
Here, in the following mathematical formula (c), W _n represents the mass fraction of the nth ultraviolet absorber, and (logP) _n represents “logP” of the nth ultraviolet absorber.

  5.0 × DS−6.7 ≦ average log P ≦ 5.0 × DS−5.1 Equation (d)

The average value of the log P of the ultraviolet absorber is (5.0 × DS-6.7) or more and (5.0 × DS-5.1) or less, and (5.0 × DS-6.5) or more. (5.0 × DS-5.2) or less is preferable. When the average value of logP is too large, the surface shape is deteriorated, and when the average value of logP is too small, the retentivity of the ultraviolet absorber under high temperature and high humidity is deteriorated.
Moreover, the compound represented by the said General formula (1) has an absorption maximum in the wavelength range of 330-360 nm.

The UV absorber preferably has a molecular weight of 250 to 1,000 from the viewpoint of volatility, more preferably 260 to 800, still more preferably 270 to 800, and 300 to 800. Is particularly preferred. A specific monomer structure may be used as long as these molecular weights are within the range, and an oligomer structure or a polymer structure in which a plurality of the monomer units are bonded may be used.
It is preferable that the ultraviolet absorber does not volatilize during the dope casting and drying process for producing the cellulose acylate film.

[Amount of compound added]
The addition amount of the above-mentioned ultraviolet absorber is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, and 0.2 to 3% by mass with respect to cellulose acylate. % Is more preferable.

[Method of adding compound]
Further, the timing of adding these ultraviolet absorbers may be any time during the dope preparation process, or may be performed at the end of the dope preparation process.

Next, the ultraviolet absorber represented by the general formula (1) will be described in detail.
R ¹ , R ² , R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or a monovalent organic group, and at least one of R ¹ , R ² and R ³ has 4 to 20 carbon atoms in total. It represents an unsubstituted branched or straight chain alkyl group, and R ¹ , R ² and R ³ are different from each other.
Examples of the substituent include an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, such as methyl, ethyl, iso-propyl, tert-butyl, and n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2 to 8, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, and particularly preferably carbon number). 2-8, for example, propargyl, 3-pentynyl, etc.), aryl groups (preferably having 6-30 carbon atoms) More preferably, it has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl and the like, and a substituted or unsubstituted amino group (preferably having 0 to 0 carbon atoms). 20, more preferably 0 to 10 carbon atoms, particularly preferably 0 to 6 carbon atoms, and examples thereof include amino, methylamino, dimethylamino, diethylamino, dibenzylamino and the like.

Further, as other substituents, an alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, and examples thereof include methoxy, ethoxy, butoxy and the like. ), An aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyloxy and 2-naphthyloxy). An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, pivaloyl and the like), an alkoxycarbonyl group ( Preferably it has 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, for example methoxycarbo And aryloxycarbonyl group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, and particularly preferably having 7 to 10 carbon atoms, such as phenyloxycarbonyl). An acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 10 carbon atoms, such as acetoxy and benzoyloxy). (Preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino), alkoxycarbonylamino group (preferably carbon 2 to 20, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms For example, methoxycarbonylamino and the like), an aryloxycarbonylamino group (preferably having 7 to 20 carbon atoms, more preferably having 7 to 16 carbon atoms, and particularly preferably having 7 to 12 carbon atoms). Carbonylamino, etc.), sulfonylamino groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino, benzenesulfonylamino, etc. ), A sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, Phenylsulfamoyl etc.), carbamoyl group ( Preferably it is C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12, for example, carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl etc. are mentioned. ), An alkylthio group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio, ethylthio, etc.), an arylthio group (preferably carbon 6 to 20, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and the like, and a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably carbon atoms). 1 to 16, particularly preferably 1 to 12 carbon atoms such as mesyl, tosyl, etc.), sulfinyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably carbon atoms). 1 to 12, for example, methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably having 1 to 1 carbon atoms) 0, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms, More preferably, it has 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include diethyl phosphoric acid amide and phenyl phosphoric acid amide), hydroxy group, mercapto group, halogen atom (for example, fluorine atom, Chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 and the hetero atom includes, for example, a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, an imidazoli , Pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, etc.), a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably Are those having 3 to 24 carbon atoms, and examples thereof include trimethylsilyl and triphenylsilyl). These substituents may be further substituted.
Further, when there are two or more substituents, they may be the same or different, and may be connected to each other to form a ring if possible, but at least one of R ¹ , R ² and R ³ is It represents an unsubstituted branched or straight chain alkyl group having 4 to 20 carbon atoms in total, and R ¹ , R ² and R ³ are different from each other.

R ¹ and R ³ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, It is more preferably a hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, more preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, and an alkyl group having 1 to 12 carbon atoms. (Preferably 4 to 12 carbon atoms) is particularly preferable.

R ² is preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, It is more preferably an alkyl group, an aryl group, an alkyloxy group, an aryloxy group or a halogen atom, more preferably a hydrogen atom or a carbon 1-12 alkyl group, particularly preferably a hydrogen atom or a methyl group. The hydrogen atom is most preferred.

R ⁴ and R ⁵ are preferably a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a substituted or unsubstituted amino group, an alkoxy group, an aryloxy group, a hydroxy group, or a halogen atom, A hydrogen atom, an alkyl group, an aryl group, an alkyloxy group, an aryloxy group and a halogen atom are more preferable, a hydrogen atom and a halogen atom are more preferable, and a hydrogen atom and a chlorine atom are particularly preferable.

  Specific examples of the compound represented by the general formula (I) are shown below, but the present invention is not limited to the following specific examples.

<< Plasticizer >>
Examples of the plasticizer that can be used for the transparent substrate film of the present invention include polyhydric alcohol ester plasticizers, glycolate plasticizers, phosphate ester plasticizers, and phthalate ester plasticizers. Particularly preferred are polyhydric alcohol plasticizers and glycolate plasticizers.
Moreover, it is preferable to set it as 16 mass% or less with respect to a film, as for the addition amount of a phosphate ester plasticizer, it is more preferable to set it as 10 mass% or less, and it is especially preferable to set it as 6 mass% or less.

  The polyhydric alcohol ester is composed of an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule.

The polyhydric alcohol used in the present invention is represented by the following general formula (2).
In the following general formula (2), R ₁ is an n-valent organic group, n is a positive integer of 2 or more, and an OH group represents an alcoholic and / or phenolic hydroxyl group)

Examples of the polyhydric alcohol represented by the general formula (2) include the following, but the present invention is not limited to these.
Specifically, adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol 1,3-butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, Examples include 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol.
Among these, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are particularly preferable.

  There is no restriction | limiting in particular as monocarboxylic acid used for the polyhydric alcohol ester of this invention, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. are used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

  Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

  As the aliphatic monocarboxylic acid, it is preferable to use a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

  Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid , Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, And unsaturated fatty acids such as oleic acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid.

  Examples of preferred alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, or derivatives thereof.

  Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenylcarboxylic acid, naphthalenecarboxylic acid, and tetralincarboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives are mentioned. Benzoic acid is particularly preferable.

  The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1,500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose ester.

  The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

  The specific compound of a polyhydric alcohol ester is shown below.

The glycolate plasticizer is not particularly limited, but a glycolate plasticizer having an aromatic ring or a cycloalkyl ring in the molecule is preferably used.
Preferred glycolate plasticizers include, for example, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, and the like.

  For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, phthalate ester In diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, dibenzyl phthalate, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl Examples of citrate plasticizers such as ethyl glycolate include triethyl citrate, tri-n-butyl citrate, acetate Le triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n-(2-ethylhexyl) citrate and the like are used.

  These plasticizers can be used alone or in combination of two or more. 4-20 mass% is preferable with respect to a cellulose ester, and, as for the usage-amount of a plasticizer, 6-16 mass% is more preferable, and 8-13 mass% is still more preferable. If the added amount of the plasticizer is too large, the film becomes too soft and the water absorption modulus decreases. If the added amount is too small, the moisture permeability of the film decreases.

  In addition to the plasticizers described above, various additives are used in the transparent base film of the present invention for the purpose of controlling film properties such as durability, moisture permeability, and elastic modulus of the substrate, and optical property values. For example, JP 2006-30937 A [0054] to [0134], JP 2003-12859 A, JP 2002-20410 A, JP 2003-222723 A [0031 to 0044], and The compounds described in JP-A-2002-22956 [0045 to 0058] can be used.

<Coating layer>
The coating layer has a low moisture permeability, and includes a single coating layer having a moisture permeability of about 1,400 g / m ² · day or less at 60 ° C. and 95% relative humidity. When measurement is difficult, a coating layer is formed on a transparent substrate film made of resin (TD80UL 60 ° C., Fujifilm Co., Ltd., moisture permeability at 95% relative humidity is about 1,400 g / m ² · day) The moisture permeability at 60 ° C. and 95% relative humidity is about 700 g / m ² · day or less.
As the moisture permeability is more preferably less than ² · day 400g / ^m, 250g / ^m more preferably less than ² · day, 100 g / ^{m 2} · day or less are particularly preferred.
When it is difficult to measure the coating layer alone, the coating layer is made of a resin transparent substrate film (Fuji Film TD80UL 60 ° C, moisture permeability at 95% relative humidity is about 1,400 g / m ² · day or less) You may define by the calculated value of the water vapor transmission rate (Pc) of the coating layer calculated | required using the following numerical formula (3) from the water vapor transmission rate at the time of forming on.
Moisture permeability of the coating layer in this case is more preferably less than ² · day 500 g / ^m, more preferably less than ² · day 300 g / ^m, and particularly preferably ² · day 110g / ^m.

1 / Pb + 1 / Pc = 1 / Pall (3)
Pb: moisture permeability of transparent substrate film Pc: moisture permeability of coating layer Pall: moisture permeability when the coating layer is formed on a resin transparent substrate film

  The measurement method of moisture permeability is "Polymer Physical Properties II" (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) Can be applied as appropriate.

Specifically, 70 mmφ of the film sample (protective film for polarizing plate) of the present invention is conditioned at 60 ° C. and 95% RH for 24 hours, respectively, and according to JIS Z-0208, moisture permeability = mass after conditioning−mass before conditioning The amount of moisture per unit area (g / m ² ) was calculated by mass to obtain moisture permeability.

<< Thickness of coating layer >>
The thickness of the coating layer is preferably 0.2 to 10 μm, more preferably 0.5 to 8 μm, and particularly preferably 1 to 5 μm. If the thickness of the coating layer is not more than the upper limit value, it is preferable because it has excellent low moisture permeability and does not cause adverse effects such as curling and deterioration of brittleness. If the curl becomes too large, it will hinder subsequent processes for producing a polarizing plate, for example, a bonding process with a polarizing film and handling. Further, it is not preferable that the curl remains not only in the manufacturing process but also as the polarizing plate, which causes display unevenness in the LCD.
Therefore, in order to reduce the curl to such an extent that it does not occur or is practically not problematic, it is preferable to set the upper limit of the coating layer thickness within the above range.
On the other hand, the lower limit of the thickness of the coating layer is defined as a range that is more preferable than moisture resistance. The coating layer consists of at least one layer, and two or more layers are also possible.

Regarding the thickness of the coating layer, in-plane uniformity is also required. The coating layer used in the protective film of the present invention may be continuously produced by wet coating on a roll-shaped transparent substrate film having a width of 1 m or more and less than 3 m and a total length of 100 m or more and less than 10,000 m. From the viewpoint of production cost, the film thickness distribution is preferably within ± 20% of the average thickness in the width and longitudinal directions, and ± 10% with respect to the average thickness. % Variation is more preferable, and a variation within ± 5% with respect to the average thickness is particularly preferable.
If the variation is within ± 20% with respect to the average thickness, the variation in the moisture permeability of the coating layer by the measurement method described later can be suppressed, and the display quality unevenness that is the effect of the present invention is further reduced.

The coating layer is not particularly limited as long as it is a resin component having low moisture permeability that is soluble in an organic solvent, and a polymer resin as a main component is preferable from the viewpoint of reducing moisture permeability.
As the polymer component, it is particularly preferable to use a hydrophobic compound such as a polymer containing a repeating unit derived from a chlorine-containing vinyl monomer, a fluorine-based polymer, and a (cyclic) olefin-based polymer as a main component. .
Since the main solvent of the vinyl alcohol polymer is water, it is not particularly preferably used in the present invention. However, when a solvent that swells or dissolves the transparent substrate is selected and used, It is preferable that the residual solvent amount be within the range.
As a resin component, it is particularly preferable to use a polymer resin as a main component. When a polyfunctional monomer that crosslinks with light or ionizing radiation is used, the residual solvent can be reduced. However, in order to make the moisture permeability within the target range, it is preferable that a polymer resin is a main component in the present invention.

<< Polymer containing repeating units derived from chlorine-containing vinyl monomer >>
A polymer containing a repeating unit derived from a chlorine-containing vinyl monomer preferable as the coating layer (hereinafter sometimes referred to as a chlorine-containing polymer) will be described.
In general, examples of the chlorine-containing vinyl monomer include vinyl chloride and vinylidene chloride. A chlorine-containing polymer can be obtained by copolymerizing these vinyl chloride or vinylidene chloride monomers with a monomer copolymerizable therewith.

[Monomer copolymerizable with chlorine-containing vinyl monomer]
Examples of the copolymerizable monomer include olefins, styrenes, acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, itaconic acid diesters, maleic acid esters, fumaric acid diesters, N- Examples thereof include monomers selected from alkylmaleimides, maleic anhydride, acrylonitrile, vinyl ethers, vinyl esters, vinyl ketones, vinyl heterocyclic compounds, glycidyl esters, unsaturated nitriles, unsaturated carboxylic acids and the like.

  Examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene and the like.

  Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, trifluoromethyl styrene, vinyl. And benzoic acid methyl ester.

Specific examples of acrylic esters and methacrylic esters include the following.
Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, t-octyl acrylate, 2-methoxyethyl acrylate, 2-butoxyethyl acrylate, 2-phenoxyethyl acrylate, chloroethyl acrylate, Cyanoethyl acrylate, dimethylaminoethyl acrylate, benzyl acrylate, methoxybenzyl acrylate, furfuryl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, oct Methacrylate, benzyl methacrylate, cyanoacetoxyethyl methacrylate, chlorobenzyl methacrylate, sulfopropyl methacrylate, N-ethyl-N-phenylaminoethyl methacrylate, 2-methoxyethyl methacrylate, 2- (3-phenylpropyloxy) ethyl methacrylate, dimethylamino Phenoxyethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, 3 -Chloro-2-hydro Cypropyl methacrylate, 2,2-dimethylhydroxypropyl acrylate, 5-hydroxypentyl acrylate, diethylene glycol monoacrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, 2,2-dimethyl-3-hydroxypropyl methacrylate, 5-hydroxypropyl Methacrylate, diethylene glycol monomethacrylate, trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate.

Specific examples of vinyl ethers include the following.
Methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethyl hexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl ether, dimethylaminoethyl Vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2,4-dichlorophenyl ether, vinyl naphthyl ether, vinyl anthranyl ether .

Specific examples of the vinyl esters include the following.
Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl dimethyl propionate, vinyl ethyl butyrate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, Vinyl butoxy acetoacetate, vinyl phenyl acetate, vinyl acetoacetate, vinyl lactate, vinyl-β-phenylbutyrate, vinyl cyclohexyl carboxylate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate.

  Acrylamides include acrylamide, methylacrylamide, ethylacrylamide, propylacrylamide, butylacrylamide, t-butylacrylamide, cyclohexylacrylamide, benzylacrylamide, hydroxymethylacrylamide, methoxyethylacrylamide, dimethylaminoethylacrylamide, phenylacrylamide, dimethylacrylamide, and diethyl. Examples include acrylamide, β-cyanoethyl acrylamide, and N- (2-acetoacetoxyethyl) acrylamide.

  Examples of methacrylamides include methacrylamide, methyl methacrylamide, ethyl methacrylamide, propyl methacrylamide, butyl methacrylamide, tert-butyl methacrylamide, cyclohexyl methacrylamide, benzyl methacrylamide, hydroxymethyl methacrylamide, methoxyethyl methacrylamide , Dimethylaminoethylmethacrylamide, phenylmethacrylamide, dimethylmethacrylamide, diethylmethacrylamide, β-cyanoethylmethacrylamide, N- (2-acetoacetoxyethyl) methacrylamide and the like.

  Further, acrylamides having a hydroxyl group can also be used, and examples thereof include N-hydroxymethyl-N- (1,1-dimethyl-3-oxo-butyl) acrylamide, N-methylolacrylamide, and N-methylol. Examples include methacrylamide, N-ethyl-N-methylol acrylamide, N, N-dimethylol acrylamide, N-ethanol acrylamide, N-propanol acrylamide, N-methylol acrylamide, and the like.

Examples of itaconic acid diesters include dimethyl itaconate, diethyl itaconate, and dibutyl itaconate. Examples of maleic acid diesters include diethyl maleate, dimethyl maleate, and dibutyl maleate.
Examples of the fumaric acid diesters include diethyl fumarate, dimethyl fumarate, dibutyl fumarate, and the like.

Examples of vinyl ketones include methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl vinyl ketone, and the like.
Examples of the vinyl heterocyclic compound include vinyl pyridine, N-vinyl imidazole, N-vinyl oxazolidone, N-vinyl triazole, and N-vinyl pyrrolidone.
Examples of glycidyl esters include glycidyl acrylate and glycidyl methacrylate.
Examples of unsaturated nitriles include acrylonitrile and methacrylonitrile.
Examples of N-alkylmaleimides include N-ethylmaleimide and N-butylmaleimide.

Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like, and further anhydrides such as fumaric acid, itaconic acid and maleic acid.
Two or more kinds of these copolymerizable monomers may be used.

  Examples of the chlorine-containing polymer in the present invention include JP-A-53-58553, JP-A-55-43185, JP-A-57-139109, JP-A-57-139136, JP-A-60. -235818, JP-A 61-108650, JP-A 62-256871, JP-A 62-280207, JP-A 63-256665, and the like.

  The proportion of the chlorine-containing vinyl monomer in the chlorine-containing polymer is preferably from 50 to 99 mass%, more preferably from 60 to 98 mass%, still more preferably from 70 to 97 mass%. If the ratio of the chlorine-containing vinyl monomer is 50% or more, problems such as deterioration of moisture permeability will not occur, and if it is 99% or less, solubility in various solvents is obtained, which is preferable. .

Chlorine-containing polymers are available from Asahi Kasei Chemicals Corporation and Kureha Chemical Corporation. There is no particular limitation as long as it can be applied with a solvent, but examples of those available from Asahi Kasei Chemicals Corporation include “Saran Resin R241C”, “Saran Resin F216”, and “Saran Resin R204”. Saran Resin F216 is preferably used because it has a larger solvent selection range because it is soluble in ketone solvents (methyl ethyl ketone, cyclohexanone, etc.).
Further, since Saran Resin R204 has high crystallinity, the moisture permeability of the coating layer can be lowered, and it is difficult to dissolve in a solvent when applying a layer having hard coat properties described later, and has a hard coat property. It is possible to prevent the performance from deteriorating due to excessive mixing with the resin.
On the other hand, Saran latex is an aqueous solvent and is not preferred in the present invention from the viewpoint of adhesion to a transparent substrate and moisture permeability.

[Compounds other than chlorine-containing vinyl monomers]
The coating layer having low moisture permeability of the present invention can also be formed by constituting the main component of the matrix constituting the layer from a hydrophobic compound other than the chlorine-containing polymer. That is, by forming a hydrophobic layer mainly composed of a hydrophobic compound, it is possible to suppress adsorption of water molecules to the membrane surface, dissolution into the membrane, passage through the membrane, and moisture permeability. Can be reduced.
Furthermore, by increasing the intermolecular interaction and other interactions between the compounds that form the matrix, or by carrying out more precise cross-linking, the degree of freedom of movement of the matrix molecules in the film is reduced, and the transparency is reduced. Wetness can be further reduced.
The binder system constituting the hydrophobic matrix that achieves these objectives includes a system composed of a hydrophobic monomer, a system composed of a hydrophobic monomer and a polyfunctional monomer (crosslinking agent), a system of a hydrophobic polymer, and a hydrophobic polymer. Examples thereof include a system composed of a crosslinking agent.
Furthermore, examples of the binder having a large interaction between the compounds include a liquid crystal monomer system, a liquid crystal monomer / crosslinking agent system, a liquid crystalline polymer, a liquid crystal polymer / crosslinking agent system, and the like. From the viewpoint of reduction, a polymer (polymer resin) system is particularly preferable.
These binders preferably have a log P value of 1.0 or more and 12.0 or less, and preferably 2.0 or more and 11.5 or less from the viewpoint of handling properties such as hydrophobicity, solubility and film-forming properties. Is more preferably 3.0 or more and 11.0 or less.

[Log P value]
The octanol-water partition coefficient (log P value) can be measured by a flask immersion method described in JIS Japanese Industrial Standard Z7260-107 (2000).
Further, the octanol-water partition coefficient (log P value) can be estimated by a computational chemical method or an empirical method instead of the actual measurement.
As a calculation method, Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987)), Viswanadhan's fragmentation method (J. Chem. Inf. Comput. Sci., 29,). 163 (1989)), Broto's fragmentation method (Eur. J. Med. Chem.-Chim. Theor., 19, 71 (1984)) and the like are preferable, but the Crippen's fragmentation method (J. Chem. Inf. Comput. Sci., 27, 21 (1987)) is more preferable.
Further, when the log P value of a certain compound varies depending on the measurement method or calculation method, it is preferable to determine whether or not the compound is within the scope of the present invention by the Crippen's fragmentation method.

Specifically as a hydrophobic monomer, a fluorine-type monomer, a cycloolefin type monomer, a monomer containing an aromatic, etc. can be used. As the fluorine-based monomer, there can be used a fluorine-containing compound having a crosslinkable or polymerizable functional group described later, a compound described in JP-A-9-5519, a compound described in JP-A-2000-159840, and the like.
As the cycloolefin monomer, for example, compounds described in JP-A-2006-83225, JP-A-5-51542, JP-A-6-313056, and JP-A-6-340849 can be used.

Specific examples of the hydrophobic polymer include fluorine-based polymers, (cyclic) olefin polymers, aromatic-containing polymers, and the like. , Compounds described in JP-A-7-70107, Reports Res. Lab. Asahi Glass Co. , Ltd., Ltd. , 55 (2005) P47-51 can be used.
As the (cyclic) olefin polymer, the resin composition described in JP-A-7-228673, JP-A-8-259784 and the like can be used.
In addition to the hydrophobic binder (monomer, polymer), the hydrophobic layer of the present invention is intended to improve the film density, reduce moisture permeability, and improve film properties such as brittleness and curl. , A polyfunctional polymerizable monomer or a crosslinkable monomer can be used in combination.
As monomers that can be used in combination, polyfunctional monomers and polyfunctional oligomers described in [Hard Coat Layer] described later can be used.

When the main component of the hydrophobic layer of the present invention is a monomer or a polymerizable compound, it can be cured and formed into a film by polymerization. As the polymerization initiator used in this case, a photoinitiator described later can be used.
When a polymerization initiator is used, the polymerization initiator is preferably used in an amount of 0.01% by mass to 10.0% by mass with respect to the monomer or polymerizable compound. The range is more preferably 1% by mass to 7.0% by mass, and still more preferably 0.5% by mass to 5.0% by mass.

[Organic solvent used for coating layer formation]
Since the coating layer is formed by coating a coating composition on a transparent substrate, the solvent used in the coating composition is an important factor. Requirements include that the above solute is sufficiently dissolved and that coating unevenness and drying unevenness are less likely to occur during the drying process.
In the present invention, since it is preferable to form a mixed region between the transparent support and the coating layer to develop the adhesion of the coating layer without providing an anchor layer or the like, the coating for forming the coating layer As the organic solvent used for the composition, it is necessary to select a solvent having a property of dissolving or swelling the base film.
If such a solvent is used in the coating solution, the coating layer is formed while the support is dissolved or swollen in the drying process immediately after coating, so that the interface between the base film and the coating layer becomes unclear, and at the same time, the coating layer The layer of the area | region which mixed the resin component of this and the resin component of the base film is formed.
The organic solvent here may be used singly or in combination of two or more. However, even when two or more of the organic solvents are used in combination, the above conditions may be satisfied in a mixed state. preferable.

  The mixed region formed after coating the coating layer is the solid content concentration of the coating layer coating solution, the solvent type, the solvent composition, the additive, the type of transparent substrate film on which the coating layer is coated, and the coating layer coating solution coating. It is affected by various conditions such as amount, drying conditions, and curing conditions. In the present invention, the above conditions are not particularly limited as long as a mixed region is formed between the transparent substrate film and the coating layer and adhesion is obtained.

  In addition, a solvent that does not dissolve or swell the transparent substrate film (for example, triacetyl cellulose film) in order to achieve both control of unevenness on the surface of the coating layer (reducing unevenness or flattening) and strength of the coating layer. It is preferable to mix at least one kind.

  The solvent having the property of dissolving or swelling the substrate film is appropriately selected depending on the transparent substrate to be used. When two or more types of solvents are used, it is preferable to use at least 30% by mass, more preferably at least 50% by mass, and at least 60% by mass of a solvent having a property of dissolving or swelling the base film. Is more preferable.

When a cellulose acylate film is selected as the base film, as a solvent having a property of dissolving or swelling the base film,
Specific examples of the ether having 3 to 12 carbon atoms include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1,3, Examples include 5-trioxane, tetrahydrofuran, anisole, and phenetole.
Specific examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone.
Specific examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, propion brewed ethyl, n-pentyl acetate, and γ- Examples include butyrolactone.
Specific examples of the organic solvent having two or more kinds of functional groups include methyl 2-methoxyacetate, methyl 2-ethoxyacetate, ethyl 2-ethoxyacetate, ethyl 2-ethoxypropionate, 2-methoxyethanol, 2- Examples include propoxyethanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone, diacetone alcohol, methyl acetoacetate, and ethyl acetoacetate. Moreover, methylene chloride can also be preferably used as another organic solvent. These can be used alone or in combination of two or more.

  In the present invention, an organic solvent having a boiling point of 100 ° C. or lower is preferably used as a solvent capable of swelling or dissolving the transparent substrate film in order to suppress the residual solvent amount to a specified amount or less. More preferably, the organic solvent having a boiling point of 100 ° C. or less that can swell or dissolve is contained in an amount of 70% by mass or more, more preferably 50% by mass or more, and particularly preferably 10% by mass or more.

  The solvent having the property of not dissolving or swelling the substrate film is appropriately selected depending on the transparent substrate to be used. When two or more kinds of solvents are used, it is preferable to contain at least 5% by mass and less than 70% by mass of a solvent having a property of dissolving or swelling at least the base film, and at least 5% by mass and less than 50% by mass. It is more preferable to contain 10% by mass or more and less than 30% by mass.

  When the base film is a cellulose acylate film preferably used in the present invention, the solvent having the property of not dissolving or swelling the base film is methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, cyclohexanol, isobutyl acetate, methyl isobutyl ketone, 2-octanone, 2-pentanone, 2-hexanone, 2-heptanone, 3-pentanone , 3-heptanone, 4-heptanone, toluene, propylene glycol monomethyl ether acetate and the like. Among these, methyl isobutyl ketone, toluene, and propylene glycol monomethyl ether acetate are particularly preferable because of the solubility of the components that form the low moisture-permeable layer. These can be used alone or in combination of two or more.

  In the present invention, in order to keep the residual solvent amount below a specified amount, the solvent that does not swell or dissolve the transparent substrate film preferably has a higher boiling point than the solvent that can swell or dissolve the transparent substrate film. More preferably, an organic solvent in the range of 100 ° C. to 150 ° C. is used, and an organic solvent having a boiling point of 100 ° C. to 150 ° C. that does not swell or dissolve the transparent substrate film is 5% by mass or more and 70% by mass in the total solvent. The content is preferably less than 5% by mass, more preferably less than 40% by mass, and still more preferably 10% by mass or more and less than 30% by mass.

In the present invention, when the chlorine-containing polymer is vinylidene chloride, it is preferable to use tetrahydrofuran as the main solvent. Further, by selecting a copolymer of vinylidene chloride, it can be dissolved in toluene, a ketone solvent, etc., and toluene, a ketone solvent, etc. can be used as a main solvent without using tetrahydrofuran. From the viewpoint of boiling point, it is particularly preferable to use tetrahydrofuran or methyl ethyl ketone as the main solvent.
When tetrahydrafuran is used, reducing properties such as p-cresol, resorcin, hydroquinone, ferrous salt, hindered phenol (for example, 2,6-di-t-butyl-4-methylphenol) are used from the viewpoint of light stabilization. It is preferable to add the substance in an amount of 0.01 to 1% by mass in the coating solution. The coating layer is preferably used because it is effective in preventing coloring of the coating layer.

  In order to improve the blocking resistance, silica powder such as Silysia (made by Fuji Silysia), Mizuka Seal (made by Mizusawa Chemical Industry), NipSeal (made by Nippon Silica Industry) is applied to the coating layer with respect to the chlorine-containing polymer. 0.2 to 1.0 part added, 0.2 to 5.0 parts of wax emulsion such as paraffin wax (manufactured by Nippon Seiwa), behenic acid (manufactured by NOF), stearic acid (manufactured by NOF) It is also preferable to use them. It is also preferable to use a modified wax as described in paragraphs [0012] to [0016] of JP-A-9-143419.

When using particles for improving blocking resistance, organic resin particles can also be used. From the viewpoint of sedimentation in the coating solution, the specific gravity is lighter than that of the silica powder, so that it is preferably used. As the organic resin particles, plastic beads are preferable, and those having particularly high transparency and a refractive index difference from the chlorine-containing polymer of 0.001 or more and 0.3 or less are preferable.
As organic resin particles, polymethyl methacrylate particles, crosslinked poly (acryl-styrene) copolymer particles, melamine resin particles, polycarbonate particles, polystyrene particles, crosslinked polystyrene particles, polyvinyl chloride particles, benzoguanamine-melamine formaldehyde particles, etc. are used. It is done.
Among the organic resin particles, crosslinked polystyrene particles, crosslinked polymethylmethacrylate particles, and crosslinked poly (acryl-styrene) particles are preferably used.

The average particle size of the organic resin particles is preferably 0.5 to 2 times the film thickness of the coating layer, more preferably 0.8 to 1.5 times, and particularly preferably 0.9 to 1.2 times. . From the viewpoint of particle aggregation and sedimentation, 0.5 to 12 μm is preferable, 0.8 to 8.0 μm is more preferable, and 1.0 to 6 μm is more preferable. It is particularly preferable to design so that the ratio of particle diameters falls within the above range.
Moreover, you may use together and use 2 or more types of organic resin particles from which a particle diameter differs.

Examples of the method for producing the organic resin particles according to the present invention include a suspension polymerization method, an emulsion polymerization method, a soap-free emulsion polymerization method, a dispersion polymerization method, a seed polymerization method and the like, and may be produced by any method. .
These production methods are described, for example, in “Experimental Methods for Polymer Synthesis” (Takayuki Otsu and Masaaki Kinoshita, Chemical Dojinsha), pages 130 and 146 to 147, “Synthetic Polymers”, Vol. 1, p. 246-290, 3rd volume, p. 1 to 108, etc., and Japanese Patent Nos. 2543503, 3508304, 2746275, 3521560, 3580320, and Japanese Patent Laid-Open No. 10-1561. Reference can be made to methods described in JP-A No. 7-2908, JP-A No. 5-297506, JP-A No. 2002-145919, and the like.

  The particles are preferably blended so as to be contained in the chlorine-containing polymer in an amount of 0.1 to 30% by mass, and blended so as to be contained in the chlorine-containing polymer in an amount of 0.2 to 5% by mass. It is more preferable, and it is particularly preferable that 0.25 to 1% by mass is contained in the chlorine-containing polymer. When the blending amount is 0.1% by mass or more and 30% by mass or less, the blocking resistance is good and the moisture permeability can be suppressed low, which is preferable.

The particle size distribution of the organic resin particles is preferably monodisperse particles in view of ensuring transparency and uniformity of the coated surface. For example, when a particle having a particle size of 20% or more than the average particle size is defined as a coarse particle, the ratio of the coarse particle is preferably 1% or less of the total number of particles, and preferably 0.1% or less. More preferred is 0.01% or less.
The particle size distribution of the organic resin particles is measured by a Coulter counter method, and the measured distribution is converted into a particle number distribution. Particles having a particle size distribution as described above are also effective means of classification after the preparation or synthesis reaction. By increasing the number of classifications or increasing the degree thereof, particles having a preferable distribution can be obtained. it can.
It is preferable to use a method such as an air classification method, a centrifugal classification method, a sedimentation classification method, a filtration classification method, or an electrostatic classification method for classification.

  Furthermore, in order to increase the adhesion between the coating layer and the transparent substrate film or other layers, isocyanate adhesives such as Coronate L (manufactured by Nippon Polyurethane) and Takenate A-3 (manufactured by Takeda Pharmaceutical Co., Ltd.) Is preferably added in an amount of 0.1 to 10.0% by mass relative to the chlorine-containing polymer. It is more preferable to add 0.2 to 5% by mass. When the addition amount is small, the effect of improving the adhesion cannot be obtained, and when the addition amount is too large, there is a possibility that adverse effects such as deterioration of the stability to light and deterioration of performance may occur.

  The cured coating layer may be composed of a single layer or a plurality of layers, but is preferably a single layer that is simple in the production process. The single layer in this case refers to a coating layer formed of the same composition, and may be formed by a plurality of coatings as long as the composition after coating and drying has the same composition. On the other hand, the term “multiple layers” refers to the formation of a plurality of compositions having different compositions.

  In the present invention, fine particles may be added to the coating layer forming coating solution. By adding fine particles, effects such as improved hardness, improved adhesion to a transparent substrate film, and reduced moisture permeability can be obtained.

[Fine particles]
As the fine particles, any of inorganic fine particles, organic fine particles, and organic-inorganic composite fine particles can be used. Examples of the inorganic fine particles include silicon dioxide particles, titanium dioxide particles, zirconium oxide particles, aluminum oxide particles, antimony oxide particles, and indium oxide particles.

  In general, the inorganic fine particles may easily form aggregates or cracks in the coating layer after curing, simply by mixing. In the present invention, in order to increase the affinity between the inorganic fine particles and the organic component, the surface of the inorganic fine particles can be treated with a surface modifier containing an organic segment.

  The filling amount of the fine particles is preferably 2 to 40% by volume, more preferably 3 to 30% by volume, and most preferably 5 to 30% by volume with respect to the volume of the coating layer after filling.

  An inorganic layered compound can also be added to the coating layer forming coating solution as described above. As the layer compound, synthetic mica and synthetic smectite are preferably used.

<Second layer>
In order to add a function further to the protective film for polarizing plates of this invention, it is preferable to provide a 2nd layer. As the second layer, a layer having hard coat properties (hereinafter sometimes referred to as a hard coat layer) for imparting physical strength of the film, an antireflection layer, and the like are provided. The hard coat layer is preferably a light-scattering layer having light scattering properties on the surface and / or inside thereof (when the surface is given scattering properties, it may be referred to as an antiglare layer). More preferably, at least a low refractive index layer is provided as an antireflection layer on the hard coat layer to reduce the reflectance. More preferably, an antireflection layer comprising a plurality of layers in which a medium refractive index layer and / or a high refractive index layer is provided on a hard coat layer and a low refractive index layer is further provided is provided. It is preferable from the aspect of rate reduction. Although an antireflection layer can be provided without providing a hard coat layer, it is preferable to provide a hard coat layer in order to improve the physical strength of the film. The hard coat layer may be composed of a laminate of two or more layers. The layer having a hard coat property can be provided on the opposite side to the layer having low moisture permeability with respect to the transparent substrate. However, the second layer is provided on the same side as the coating layer, and is transparent on the opposite side of the coating layer. A configuration in which the substrate surface is bonded to a polarizer via an adhesive is preferable.

  The hard coat layer and antireflection layer that can be used in the present invention will be described below. In the present invention, various types of layers can be provided as the coating layer, and the requirements for the hard coat layer may vary depending on the type of the coating layer. Individual descriptions are described in the description of the coating layer. Describe common contents.

<< Configuration of Second Layer >>
As a preferred embodiment, the refractive index, the film thickness, the number of layers, the layer order, etc. are set so that the reflectance is reduced by optical interference on a transparent base film or a coating layer provided with a hard coat layer. The structure laminated | stacked in consideration is mentioned. The simplest configuration of the antireflection layer is a configuration in which only the low refractive index layer is coated on the hard coat layer. In order to further reduce the reflectance, the antireflection layer is composed of a combination of a high refractive index layer having a higher refractive index than that of the transparent substrate film and a low refractive index layer having a lower refractive index than that of the transparent substrate film. Is preferred. As a structural example, two layers of a high refractive index layer / low refractive index layer from the transparent base film side, or three layers having different refractive indices are used as a medium refractive index layer (a transparent base film or a hard coat layer). Some layers have a high refractive index and a lower refractive index than the high refractive index layer) / high refractive index layer / low refractive index layer, and so on. Has been. Among them, from the viewpoint of durability, optical characteristics, cost, productivity, etc., it is preferable to apply a medium refractive index layer / high refractive index layer / low refractive index layer in this order on a transparent substrate film having a hard coat layer. JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706 and the like.
Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  Examples of preferred layer configurations of the hard coat layer and antireflection layer of the present invention are shown below. The antireflection film of the present invention is not particularly limited to these layer configurations as long as the reflectance can be reduced by optical interference. In the following configuration, the transparent substrate film has a coating layer formed on at least one of the hard coat layer and / or the antireflection layer side or the opposite side, and includes the coating layer as a transparent substrate film. In the following constitution, the antiglare layer preferably basically has a hard coat property, but when it is used by being laminated with a hard coat layer, it may not have a hard coat property. In order to improve the hard coat property and control the surface form, it is also preferable to use a laminate of an antiglare layer having a hard coat property and a hard coat layer.

Transparent substrate film / low refractive index layer Transparent substrate film / antistatic layer / low refractive index layer Transparent substrate film / antiglare layer / low refractive index layer Transparent substrate film / antiglare layer / antistatic layer Layer / low refractive index layer transparent substrate film / hard coat layer / antiglare layer / low refractive index layer transparent substrate film / hard coat layer / antiglare layer / antistatic layer / low refractive index layer transparent substrate Film / hard coat layer / antistatic layer / antiglare layer / low refractive index layer Transparent substrate film / hard coat layer / high refractive index layer / low refractive index layer Transparent substrate film / hard coat layer / antistatic layer / High refractive index layer / Low refractive index layer Transparent substrate film / Hard coat layer / Medium refractive index layer / High refractive index layer / Low refractive index layerTransparent substrate film / Anti-glare layer / High refractive index layer / Low Refractive index layer Transparent substrate film / Anti-glare layer / Medium refractive index layer / High refractive index layer / Low refractive index layer Bright base film / antistatic layer / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index layer Antistatic layer / transparent base film / hard coat layer / medium refractive index layer / high refractive index layer / Low refractive index layer Transparent substrate film / Antistatic layer / Anti-glare layer / Medium refractive index layer / High refractive index layer / Low refractive index layerAntistatic layer / Transparent substrate film / Anti-glare layer / Medium refractive index layer / High refractive index layer / Low refractive index layer Antistatic layer / Transparent substrate film / Anti-glare layer / High refractive index layer / Low refractive index layer / High refractive index layer / Low refractive index layer

  Further, as another aspect, an aspect in which a layer necessary for the purpose of imparting hard coat property, antifouling property and the like is provided without actively using optical interference is also preferable.

  The example of the preferable layer structure of the film of the said aspect is shown below. In the following configuration, the transparent substrate film has a moisture-proof layer formed on at least one of the hard coat layer and / or the antireflection layer side or the opposite side, and includes the coating layer to form a transparent substrate film. In the following constitution, the antiglare layer preferably basically has a hard coat property, but when it is used by being laminated with a hard coat layer, it may not have a hard coat property. In order to improve the hard coat property and control the surface form, it is also preferable to use a laminate of an antiglare layer having a hard coat property and a hard coat layer.

Transparent substrate film / hard coat layer Transparent substrate film / hard coat layer / hard coat layer Transparent substrate film / antiglare layer Transparent substrate film / antiglare layer / antiglare layer Transparent substrate film / Hard coat layer / antiglare layer Transparent substrate film / antiglare layer / hard coat layer Transparent substrate film / antistatic layer Transparent substrate film / antistatic layer / hard coat layer Transparent substrate film / hard coat Layer / antifouling layer • antistatic layer / transparent substrate film / hard coat layer • antistatic layer / transparent substrate film / antiglare layer • antiglare layer / transparent substrate film / antistatic layer

  These layers can be formed by methods such as vapor deposition, atmospheric pressure plasma, and coating. From the viewpoint of productivity, it is preferably formed by coating.

  Each constituent layer will be described below.

[Hard coat layer]
The refractive index of the hard coat layer in the present invention is preferably in the range of 1.48 to 2.00, more preferably 1.49 to from the optical design for obtaining an antireflection film. 1.90, more preferably 1.50-1.80. In an embodiment in which at least one low refractive index layer is provided on the hard coat layer, which is a preferred embodiment of the present invention, the antireflection property is lowered if the refractive index is too small, and the color of the reflected light is too large. Tend to be stronger.

The thickness of the hard coat layer is usually about 0.5 μm to 50 μm, preferably 1 μm to 20 μm, more preferably 2 μm to 15 μm, and most preferably 3 μm, from the viewpoint of imparting sufficient durability and impact resistance to the film. ~ 12 μm.
The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in the pencil hardness test.
Furthermore, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of an ionizing radiation curable compound. For example, it may be formed by coating a coating composition containing an ionizing radiation-curable polyfunctional monomer or polyfunctional oligomer on a transparent support and subjecting the polyfunctional monomer or polyfunctional oligomer to a crosslinking reaction or a polymerization reaction. it can.
The functional group of the ionizing radiation-curable polyfunctional monomer or polyfunctional oligomer is preferably a light, electron beam, or radiation polymerizable group, and among them, a photopolymerizable functional group is preferable.
Examples of the photopolymerizable functional group include unsaturated polymerizable functional groups such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group. Among them, a (meth) acryloyl group is preferable.

  Instead of or in addition to the monomer having a polymerizable unsaturated group, a crosslinkable functional group may be introduced into the binder. Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group, and an active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer having a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. That is, in the present invention, the crosslinkable functional group may not be immediately reactive but may be reactive as a result of decomposition. The binder having these crosslinkable functional groups can form a crosslinked structure by heating after coating.

  The hard coat layer contains matte particles having an average particle size of 1.0 to 15.0 μm, preferably 1.5 to 10.0 μm, such as inorganic compound particles or resin particles, for the purpose of imparting internal scattering properties. May be.

  For the purpose of controlling the refractive index of the hard coat layer, a high refractive index monomer, inorganic particles, or both can be added to the binder of the hard coat layer. In addition to the effect of controlling the refractive index, the inorganic particles also have the effect of suppressing cure shrinkage due to the crosslinking reaction. In the present invention, a polymer formed by polymerizing the polyfunctional monomer and / or the high refractive index monomer after the formation of the hard coat layer, and the inorganic particles dispersed therein are referred to as a binder.

The haze of the hard coat layer varies depending on the function imparted to the protective film for a polarizing plate.
When maintaining the sharpness of the image, suppressing the reflectance of the surface, and not imparting the light scattering function inside and on the surface of the hard coat layer, the haze value is preferably as low as possible, specifically 10% or less is preferable, More preferably, it is 5% or less, and most preferably 2% or less.

On the other hand, when the antiglare function is imparted by surface scattering of the hard coat layer, the surface haze is preferably 0.5% to 15%, and more preferably 1% to 10%.
In addition, when it is difficult to see the pattern, color unevenness, brightness unevenness, glare, etc. of the liquid crystal panel due to internal scattering of the hard coat layer, or to add the function of expanding the viewing angle by scattering, the internal haze value (from the total haze value) The value obtained by subtracting the surface haze value) is preferably 10% to 90%, more preferably 15% to 80%, and most preferably 20% to 70%.
The film of the present invention can freely set surface haze and internal haze according to the purpose.

  In addition, for the surface irregularity shape of the hard coat layer, in order to obtain a clear surface for the purpose of maintaining the sharpness of the image, among the characteristics indicating the surface roughness, for example, the centerline average roughness (Ra) is set. It is preferable to be 0.08 μm or less. Ra is more preferably 0.07 μm or less, and still more preferably 0.06 μm or less. In the film of the present invention, the surface unevenness of the hard coat layer is dominant to the surface unevenness of the film, and the center line average roughness of the antireflection film is adjusted by adjusting the center line average roughness of the hard coat layer. It can be set as the said range.

  In order to maintain the sharpness of the image, it is preferable to adjust the clarity of the transmitted image in addition to adjusting the uneven shape of the surface. The clearness of the transmitted image of the clear antireflection film is preferably 60% or more. The transmitted image clarity is generally an index indicating the degree of blurring of an image reflected through a film, and the larger this value, the clearer and better the image viewed through the film. The transmitted image definition is preferably 70% or more, and more preferably 80% or more.

[Photoinitiator]
Examples of photo radical polymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides (JP-A No. 2001-139663, etc.), 2, 3 -Dialkyldione compounds, disulfide compounds, fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, coumarins and the like.

These initiators may be used alone or in combination.
“Latest UV Curing Technology”, Technical Information Association, 1991, p. 159, and “UV curing system” written by Kayo Kiyomi, 1989, General Technology Center, p. Various examples are also described in 65-148 and are useful in the present invention.

  Commercially available photo radical polymerization initiators include KAYACURE (DETX-S, BP-100, BDKM, CTX, BMS, 2-EAQ, ABQ, CPTX, EPD, ITX, QTX, BTC, manufactured by Nippon Kayaku Co., Ltd. MCA, etc.), Irgacure (651, 184, 500, 819, 907, 369, 1173, 1870, 2959, 4265, 4263, etc.) manufactured by Ciba Specialty Chemicals, Ltd., Esacure (KIP100F, KB1, manufactured by Sartomer) EB3, BP, X33, KT046, KT37, KIP150, TZT) and the like and combinations thereof are preferable examples.

  It is preferable to use a photoinitiator in the range of 0.1-15 mass parts with respect to 100 mass parts of polyfunctional monomers, More preferably, it is the range of 1-10 mass parts.

[Surface improver]
The coating liquid used to produce any layer on the support has at least one of fluorine and silicone surfaces to improve surface defects (coating irregularities, drying irregularities, point defects, etc.) It is preferable to add a state improver.

  The surface improver preferably changes the surface tension of the coating solution by 1 mN / m or more. Here, when the surface tension of the coating liquid changes by 1 mN / m or more, the surface tension of the coating liquid after the addition of the surface conditioner is added, including the concentration process during coating / drying. It means that it changes by 1 mN / m or more as compared with the surface tension of the coating liquid that has not been applied. Preferably, it is a surface conditioner that has the effect of lowering the surface tension of the coating solution by 1 mN / m or more, more preferably a surface conditioner that lowers by 2 mN / m or more, and particularly preferably a surface conditioner that lowers by 3 mN / m or more. .

  Preferable examples of the fluorine-based surface improver include compounds containing a fluoroaliphatic group. Examples of preferred compounds include those described in JP-A-2005-115359, JP-A-2005-221963, and JP-A-2005-234476.

[Anti-glare layer]
The antiglare layer is formed for the purpose of contributing to the film antiglare properties due to surface scattering and preferably hard coat properties for improving the scratch resistance of the film. Therefore, in this invention, it can be used as one embodiment of a hard-coat layer.

  As a method for imparting anti-glare properties, a method of laminating and forming a mat-shaped shaping film having fine irregularities on the surface as described in JP-A-6-16851, as described in JP-A-2000-206317 A method of forming by curing shrinkage of an ionizing radiation curable resin due to a difference in the amount of ionizing radiation applied, and by reducing the mass ratio of a good solvent to a light transmitting resin by drying as described in JP-A No. 2000-338310. A method of solidifying a light-sensitive fine particle and a translucent resin while gelling to form unevenness on the surface of the coating film, a method of imparting surface unevenness by external pressure as described in JP-A-2000-275404, A method for imparting surface irregularities by external pressure as described in Kai 2000-275404, and a mixture of a plurality of polymers as described in JP-A-2005-195819. How the solvent from the solution to form a surface unevenness by utilizing the fact that the phase separation in the process of evaporation, are known, such as, can use these known methods.

-Translucent particles-
One preferred embodiment of the antiglare layer that can be used in the present invention contains, as essential components, a binder that can impart hard coat properties, translucent particles for imparting antiglare properties, and a solvent. Surface irregularities are formed by the protrusions of the light-transmitting particles themselves or the protrusions formed of an aggregate of a plurality of particles. The antiglare layer having antiglare properties preferably has both antiglare properties and hard coat properties.

Specific examples of the translucent particles include inorganic compound particles such as silica particles and TiO ₂ particles; resin particles such as acrylic particles, crosslinked acrylic particles, polystyrene particles, crosslinked styrene particles, melamine resin particles, and benzoguanamine resin particles. Are preferred. Of these, crosslinked styrene particles, crosslinked acrylic particles, and silica particles are preferred. The shape of the mat particle can be either spherical or indefinite.

  Two or more kinds of mat particles having different particle diameters may be used in combination. It is possible to impart anti-glare properties with mat particles having a larger particle size and to impart other optical characteristics with mat particles having a smaller particle size. For example, when an anti-glare antireflection film is attached to a high-definition display of 133 ppi or higher, a problem in display image quality called “glare” may occur. “Glitter” is derived from the fact that the pixels are enlarged or reduced due to the unevenness present on the surface of the antiglare and antireflection film, resulting in loss of brightness uniformity, but the particle size is smaller than the matte particles that impart antiglare properties. Thus, the use of mat particles different from the refractive index of the binder can greatly improve the performance.

The mat particles are preferably matte particle amount in the formed antiglare hard coat layer 10~1,000mg / ^{m 2,} more preferably contained in the antiglare layer so that 100 to 700 mg / ^{m 2} The

  The film thickness of the antiglare layer is preferably 1 to 20 μm, and more preferably 2 to 10 μm. By setting it within the above range, hard coat properties, curling, and brittleness can be satisfied.

  On the other hand, the center line average roughness (Ra) of the antiglare layer is preferably in the range of 0.09 to 0.40 μm. If it exceeds 0.40 μm, problems such as glare and whitening of the surface when external light is reflected occur. Further, it is preferable that the value of the transmitted image definition is 5 to 60%.

  The strength of the antiglare layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in the pencil hardness test.

-Phase separation-
As an example of a technique for imparting anti-glare properties other than expressing anti-glare properties using translucent particles that can be used in the present invention, unevenness is formed on the surface of the coating film by spinodal decomposition of a plurality of polymers. A method is mentioned.
Moreover, it becomes possible to give favorable light diffusibility by giving a difference in the refractive index of the phase isolate | separated especially.
The light scattering layer formed by spinodal decomposition is composed of a plurality of polymers having different refractive indexes, and is usually a phase having at least a co-continuous phase structure in an operating atmosphere (especially at room temperature of about 10 to 30 ° C.). A separation structure is formed.
The co-continuous phase structure is formed by spinodal decomposition from a liquid phase containing a plurality of polymers (liquid phase at room temperature, for example, a mixed liquid or a solution). The bicontinuous phase structure is usually formed by spinodal decomposition through evaporation of a solvent using a composition (for example, a mixed solution or a solution) containing a plurality of polymers and forming a liquid phase at room temperature. Since such a light scattering layer is formed from a liquid phase, it has a uniform and fine co-continuous phase structure.
When such a transmissive light scattering sheet is used, incident light is substantially isotropically scattered, and directivity can be imparted to the transmitted scattered light. Therefore, both high light scattering and directivity can be achieved.

  In order to enhance light scattering properties, a plurality of polymers can be used in combination so that the difference in refractive index is, for example, about 0.01 to 0.2, preferably about 0.1 to 0.15. If the difference in refractive index is less than 0.01, the intensity of the transmitted scattered light decreases. If the difference in refractive index is greater than 0.2, high directivity cannot be imparted to the transmitted scattered light.

  The plurality of polymers include, for example, styrene resins, (meth) acrylic resins, vinyl ester resins, vinyl ether resins, halogen-containing resins, olefin resins (including alicyclic olefin resins), polycarbonate resins, and polyesters. Resin, polyamide resin, thermoplastic polyurethane resin, polysulfone resin (polyethersulfone, polysulfone, etc.), polyphenylene ether resin (2,6-xylenol polymer, etc.), cellulose derivatives (cellulose esters, cellulose carbamates) , Cellulose ethers, etc.), silicone resins (polydimethylsiloxane, polymethylphenylsiloxane, etc.), rubbers or elastomers (diene rubbers such as polybutadiene, polyisoprene, styrene-butadiene copolymers, Acrylonitrile - butadiene copolymer, acrylic rubber, urethane rubber, silicone rubber, etc.) can be chosen a suitable combination and the like.

  Preferred polymers include, for example, styrene resins, (meth) acrylic resins, vinyl ester resins, vinyl ether resins, halogen-containing resins, alicyclic olefin resins, polycarbonate resins, polyester resins, polyamide resins, Cellulose derivatives, silicone resins, rubbers or elastomers are included. As the plurality of polymers, a resin that is non-crystalline and is soluble in an organic solvent (in particular, a common solvent capable of dissolving the plurality of polymers) is usually used. In particular, resins with high moldability or film formability, transparency and weather resistance, such as styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (cellulose esters, etc.) Etc. are preferable.

  These plural polymers can be used in appropriate combinations. For example, in a combination of polymers, at least one polymer may be converted to a cellulose derivative, particularly a cellulose ester (eg, cellulose C2-4 alkylcarboxyl such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, etc. Acid esters) and may be combined with other polymers.

  The glass transition temperature of the polymer can be selected from the range of, for example, −100 ° C. to 250 ° C., preferably −50 to 230 ° C., more preferably about 0 to 200 ° C. (for example, about 50 to 180 ° C.). From the viewpoint of sheet strength and rigidity, the glass transition temperature of at least one of the constituent polymers is 50 ° C. or higher (for example, about 70 to 200 ° C.), preferably 100 ° C. or higher (for example, 100 to 170 ° C.). It is advantageous that The mass average molecular weight of the polymer can be selected from the range of, for example, about 1,000,000 or less (about 10,000 to 1,000,000), preferably about 10,000 to 700,000.

  Since the present invention employs a wet method in which a solvent is evaporated from a liquid phase containing a plurality of polymers and spinodal decomposition is performed, in principle, a substantially isotropic common is used regardless of the compatibility of the plurality of polymers. A light scattering layer having a continuous phase structure can be formed. For this reason, it may be configured by combining a plurality of mutually compatible polymers. However, in order to easily control the phase separation structure by spinodal decomposition and to form a co-continuous phase structure efficiently, incompatible (phase separation) In many cases, a plurality of polymers are combined.

The plurality of polymers can be constituted by a combination of the first polymer and the second polymer, and each of the first polymer and the second polymer may be constituted by a single resin or a plurality of resins. Also good.
The combination of the first polymer and the second polymer is not particularly limited and is appropriately selected depending on the purpose. For example, the first polymer is a cellulose derivative (for example, cellulose esters such as cellulose acetate propionate). The second polymer is a styrene resin (polystyrene, styrene-acrylonitrile copolymer, etc.), a (meth) acrylic resin (polymethyl methacrylate, etc.), an alicyclic olefin resin (norbornene is a single amount) Polymer, etc.), polycarbonate resin, polyester resin (poly C2-4 alkylene arylate copolyester, etc.) and the like.

  The ratio of the first polymer to the second polymer is, for example, the former / the latter = about 10/90 to 90/10 (mass ratio), preferably about 20/80 to 80/20 (mass ratio), The ratio is preferably about 30/70 to 70/30 (mass ratio), particularly about 40/60 to 60/40 (mass ratio). When the ratio of one polymer is too large, the volume ratio between the separated phases is biased, so that the intensity of scattered light decreases. In addition, when forming a sheet | seat with 3 or more some polymer, content of each polymer is 1-90 mass% normally (for example, 1-70 mass%, Preferably it is 5-70 mass%, More preferably, it is 10 Can be selected from a range of about 70 mass%.

The light scattering layer constituting the light scattering sheet of the present invention has at least a co-continuous phase structure. The co-continuous phase structure is sometimes referred to as a co-continuous structure or a three-dimensional continuous or connected structure, and means a structure in which at least two constituent polymer phases are continuous (for example, a network structure). .
The light scattering layer only needs to have at least a co-continuous phase structure, and may have a structure in which a co-continuous phase structure and a droplet phase structure (independent or isolated phase structure) are mixed.
In spinodal decomposition, a co-continuous phase structure is formed with the progress of phase separation, and when the phase separation is further advanced, the continuous phase becomes discontinuous by its surface tension, resulting in a droplet phase structure (spherical, true spherical) Sea island structure of independent phases).
Therefore, depending on the degree of phase separation, an intermediate structure between the co-continuous phase structure and the droplet phase structure, that is, a phase structure in the transition from the co-continuous phase to the droplet phase can be formed.
In the present invention, the intermediate structure is also referred to as a co-continuous phase structure. When the phase separation structure is a mixed structure of a co-continuous phase structure and a droplet structure, the ratio of the droplet phase (independent polymer phase) is, for example, 30% or less (volume ratio), preferably 10% or less ( Volume ratio). The shape of the co-continuous phase structure is not particularly limited, and may be a network shape, particularly a random network shape.

  The bicontinuous phase structure is generally isotropic with reduced anisotropy in the layer or sheet plane. Note that isotropic means that the average interphase distance of the co-continuous phase structure is substantially equal in any direction in the sheet plane.

The bicontinuous phase structure usually has regularity in the interphase distance (distance between the same phases). For this reason, the light scattered on the sheet is directed to a specific direction by Bragg reflection.
Therefore, even when mounted on a reflective liquid crystal display device, the transmitted scattered light can be directed in a certain direction, the display screen can be made highly bright, and a conventional particle-dispersed transmissive light scattering sheet Thus, a problem that cannot be solved, that is, reflection of a light source (for example, a fluorescent lamp) on the panel can be avoided.

  In the light scattering sheet, the average interphase distance between the co-continuous phases is, for example, about 0.5 to 20 μm (for example, 1 to 20 μm), preferably about 1 to 15 μm (for example, 1 to 10 μm). If the average interphase distance is too small, it is difficult to obtain high scattered light intensity, and if the average interphase distance is too large, the directivity of transmitted scattered light decreases.

The average interphase distance of the co-continuous layer can be calculated from a photomicrograph (such as a transmission microscope, a phase contrast microscope, or a confocal laser microscope) of the light scattering layer or light scattering sheet.
In addition, the scattering angle θ at which the scattered light intensity is maximized is measured by a method similar to the scattered light directivity evaluation method described later, and the average interphase distance d of the co-continuous phase is calculated from the following Bragg reflection condition equation. May be. In the following formula, d is the average interphase distance of co-continuous phases, θ is the scattering angle, and λ is the wavelength of light.

2d · sin (θ / 2) = λ

-Formation of light scattering layer by embossing method-
As an example of a method for producing a light scattering layer, a method for producing a light scattering layer by an embossing method can be given as an example of a method other than the use of translucent particles to exhibit antiglare properties.
The light scattering layer prepared by the embossing method is an ionizing radiation curable resin composition or a thermosetting resin composition formed on a transparent substrate with a mat-shaped molding film having fine irregularities on the surface. A light diffusion layer consisting essentially of is formed.
When the resin is an ionizing radiation curable resin composition, the light scattering layer is produced by coating the ionizing radiation curable resin composition on a transparent substrate and then applying the ionizing radiation curable resin. By laminating a mat-shaped shaped film having fine irregularities on the surface of the uncured coating film of the composition, and then irradiating ionizing radiation on the coated film on which the shaped film is laminated, It is preferable to manufacture the coating film of the ionizing radiation curable resin composition by a manufacturing method in which the shaped film is peeled from the cured coating film of the ionizing radiation curable resin.
When the resin is a thermosetting resin composition, the thermosetting resin composition is applied on a transparent substrate, and then the uncured coating film of the applied thermosetting resin composition is applied. A mat-like shaped film having fine irregularities on the surface is laminated, and then the coating film laminated with the shaped film is heated and cured, and then the cured thermosetting resin composition is applied. It is preferable to manufacture by the manufacturing method which peels a shaping film from a film | membrane.

When laminating the shaping film on the coating film of the uncured ionizing radiation curable resin composition, if the coated resin is of a solvent dilution type, the solvent is dried and then laminating, If the applied resin is solventless, lamination is performed as it is.
The film forming component of the ionizing radiation curable resin composition used for the light diffusing layer of the embossing method is preferably one having an acrylate functional group, such as a polyester resin, polyether resin, acrylic resin having a relatively low molecular weight. , Epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, oligomers such as (meth) acrylates of polyfunctional compounds such as polyhydric alcohols, or prepolymers and ethyl (meta) as a reactive diluent ) Acrylate, ethylhexyl (meth) acrylate, monofunctional monomers such as styrene, methylstyrene, N-vinylpyrrolidone and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, Pyrene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) ) Those containing a relatively large amount of acrylate or the like can be used.

  Particularly preferably, a mixture of polyester acrylate and polyurethane acrylate is used. The reason is that polyester acrylate is very hard and suitable for obtaining a hard coat, but polyester acrylate alone has low impact and is brittle. In order to give the properties, polyurethane acrylate is used in combination. The blending ratio of polyurethane acrylate to 100 parts by mass of polyester acrylate is 30 parts by mass or less. If this value is exceeded, the coating film is too soft and the hardness is lost.

  Furthermore, in order to make the ionizing radiation curable resin composition into an ultraviolet curable resin composition, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetra Methyl thiuram monosulfide, thioxanthones, and n-butylamine, triethylamine, tri-n-butylphosphine, and the like can be used as a photosensitizer. In particular, in the present invention, it is preferable to mix urethane acrylate as an oligomer and dipentaerythritol hexa (meth) acrylate as a monomer.

-High refractive index layer and medium refractive index layer-
When the film of the present invention is provided with a high refractive index layer and a medium refractive index layer and optical interference is used together with the low refractive index layer described later, the antireflection property can be enhanced.
In the following specification, the high refractive index layer and the medium refractive index layer may be collectively referred to as a high refractive index layer. In the present invention, “high”, “medium”, and “low” in the high refractive index layer, medium refractive index layer, and low refractive index layer represent the relative refractive index relationship between the layers. In terms of the relationship with the transparent support, the refractive index preferably satisfies the relationship of transparent support> low refractive index layer, high refractive index layer> transparent support.
In the present specification, the high refractive index layer, the middle refractive index layer, and the low refractive index layer may be collectively referred to as an antireflection layer.

  In order to construct an antireflection layer by constructing a low refractive index layer on the high refractive index layer, the refractive index of the high refractive index layer is preferably 1.55 to 2.40, and 1.60. Is more preferably ˜2.20, still more preferably 1.65 to 2.10, and particularly preferably 1.80 to 2.00.

  When an antireflective film is prepared by coating a medium refractive index layer, a high refractive index layer, and a low refractive index layer in order from the support, the refractive index of the high refractive index layer is 1.65 to 2.40. Preferably, it is 1.70 to 2.20. The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.55 to 1.80.

Specific examples of the inorganic particles used in the high refractive index layer and the medium refractive index layer include TiO ₂ , ZrO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO and SiO _2. Etc. TiO ₂ and ZrO ₂ are particularly preferable in terms of increasing the refractive index. The surface of the inorganic filler is also preferably subjected to a silane coupling treatment or a titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with a binder species on the filler surface is preferably used.

The content of the inorganic particles in the high refractive index layer is preferably 10 to 90% by mass, more preferably 15 to 80% by mass, and particularly preferably 15 to 75% by mass with respect to the mass of the high refractive index layer. . Two or more kinds of inorganic particles may be used in combination in the high refractive index layer.
When the low refractive index layer is provided on the high refractive index layer, the refractive index of the high refractive index layer is preferably higher than the refractive index of the transparent support.
The high refractive index layer contains an ionizing radiation curable compound containing an aromatic ring, an ionizing radiation curable compound containing a halogenated element other than fluorine (for example, Br, I, Cl, etc.), and atoms such as S, N, P, etc. A binder obtained by a crosslinking or polymerization reaction such as an ionizing radiation curable compound can also be preferably used.

  The film thickness of the high refractive index layer can be appropriately designed depending on the application. When using a high refractive index layer as an optical interference layer described later, the thickness is preferably 30 to 200 nm, more preferably 50 to 170 nm, and particularly preferably 60 to 150 nm.

  The haze of the high refractive index layer is preferably as low as possible when it does not contain particles that impart an antiglare function. It is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less. The high refractive index layer is preferably constructed directly on the transparent support or via another layer.

-Low refractive index layer-
In order to reduce the reflectance of the film of the present invention, it is preferable to use a low refractive index layer.
The refractive index of the low refractive index layer is preferably 1.20 to 1.46, more preferably 1.25 to 1.46, and particularly preferably 1.30 to 1.40.
The thickness of the low refractive index layer is preferably 50 to 200 nm, and more preferably 70 to 100 nm.
The haze of the low refractive index layer is preferably 3% or less, more preferably 2% or less, and particularly preferably 1% or less. The specific strength of the low refractive index layer is preferably H or more, more preferably 2H or more, and particularly preferably 3H or more in a pencil hardness test under a 500 g load.
Further, in order to improve the antifouling performance of the protective film for polarizing plate, the surface contact angle with respect to water is preferably 90 degrees or more, more preferably 95 degrees or more, and 100 degrees or more. Particularly preferred.
Preferred embodiments of the cured product composition include (1) a composition containing a fluorine-containing polymer having a crosslinkable or polymerizable functional group, and (2) a hydrolysis condensate of a fluorine-containing organosilane material as a main component. And (3) a composition containing a monomer having two or more ethylenically unsaturated groups and inorganic fine particles having a hollow structure.

(1) Fluorine-containing compound having a crosslinkable or polymerizable functional group As the fluorine-containing compound having a crosslinkable or polymerizable functional group, a fluorine-containing monomer and a monomer having a crosslinkable or polymerizable functional group may be used. A polymer is mentioned. Examples of the fluorine-containing monomer include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.), (meta ) Acrylic acid part, or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemical) or M-2020 (manufactured by Daikin)), complete or partially fluorinated vinyl ethers, and the like.

  As one example of the monomer for imparting a crosslinkable group, a (meth) acrylate monomer having a crosslinkable functional group in the molecule in advance, such as glycidyl methacrylate, can be mentioned. In another embodiment, after synthesizing a fluorinated copolymer using a monomer having a functional group such as a hydroxyl group, the monomer is further modified to introduce a crosslinkable or polymerizable functional group by modifying the substituent. It is. These monomers include (meth) acrylate monomers having a carboxyl group, hydroxyl group, amino group, sulfonic acid group, etc. (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.) Is mentioned. The latter embodiment is disclosed in Japanese Patent Laid-Open Nos. 10-25388 and 10-147739.

The fluorine-containing copolymer may contain a copolymerizable component as appropriate from the viewpoints of solubility, dispersibility, coating property, antifouling property, antistatic property and the like. In particular, for imparting antifouling properties and slipperiness, it is preferable to introduce silicone, and it can be introduced into both the main chain and the side chain.
The polysiloxane partial structure introduction method to the main chain is, for example, an azo group-containing polysiloxane amide described in JP-A-6-93100 (VPS-0501, 1001 (trade name; Wako Pure Chemical Industries, Ltd. And a method using a polymer-type initiator such as a company)). Moreover, the method of introduce | transducing into a side chain is J. for example. Appl. Polym. Sci. As described in 2000, 78, 1955, JP-A-56-28219, etc., a polysiloxane having a reactive group at one end (for example, Silaplane series (manufactured by Chisso Corporation)) is introduced by a polymer reaction. The method can be synthesized by a method of polymerizing a polysiloxane-containing silicon macromer, and both methods can be preferably used.

As described in JP 2000-17028 A, a curing agent having a polymerizable unsaturated group may be used in combination with the above polymer.
Moreover, combined use with the compound which has a fluorine-containing polyfunctional polymerizable unsaturated group as described in Unexamined-Japanese-Patent No. 2002-145952 is also preferable. Examples of the compound having a polyfunctional polymerizable unsaturated group include monomers having two or more ethylenically unsaturated groups.
Moreover, the hydrolysis-condensation product of the organolane described in Unexamined-Japanese-Patent No. 2004-170901 is also preferable, and the hydrolysis-condensation product of the organosilane containing a (meth) acryloyl group is especially preferable.
These compounds are particularly preferred because they have a large combined effect for improving scratch resistance, particularly when a compound having a polymerizable unsaturated group is used in the polymer body.

When the polymer itself does not have sufficient curability, the necessary curability can be imparted by blending a crosslinkable compound. For example, when the polymer main body contains a hydroxyl group, various amino compounds are preferably used as the curing agent.
The amino compound used as the crosslinkable compound is, for example, a compound containing a total of two or more of any one or both of a hydroxyalkylamino group and an alkoxyalkylamino group. Specifically, for example, a melamine compound, Examples include urea compounds, benzoguanamine compounds, glycoluril compounds, and the like. For curing these compounds, an organic acid or a salt thereof is preferably used.
Specific examples of these fluorine-containing polymers are described in JP2003-222702A, JP2003-183322A, and the like.

(2) Hydrolyzed condensate of fluorine-containing organosilane material A composition containing a hydrolyzed condensate of a fluorine-containing organosilane compound as a main component is also preferable because of its low refractive index and high hardness on the coating film surface. A condensate of a tetraalkoxysilane with a compound containing hydrolyzable silanol at one or both ends with respect to the fluorinated alkyl group is preferred. Specific compositions are described in JP-A No. 2002-265866 and JP-A No. 2002-317152.

(3) A composition containing a monomer having two or more ethylenically unsaturated groups and inorganic fine particles having a hollow structure As yet another preferred embodiment, a low refractive index layer comprising low refractive index particles and a binder can be mentioned. .
The low refractive index particles may be organic or inorganic, but particles having pores inside are preferable.
Specific examples of the hollow particles are described in the silica-based particles described in JP-A-2002-79616.
The particle refractive index is preferably 1.15 to 1.40, more preferably 1.20 to 1.30. Examples of the binder include monomers having two or more ethylenically unsaturated groups described on the page of the light diffusion layer.

  It is preferable to add the polymerization initiator described in the page of the light scattering layer to the low refractive index layer of the present invention. When a radically polymerizable compound is contained, 1 to 10 parts by mass, preferably 1 to 5 parts by mass of a polymerization initiator can be used with respect to the compound.

  In the low refractive layer of the present invention, inorganic particles can be used in combination. In order to impart scratch resistance, fine particles having a particle size of 15% to 150%, preferably 30% to 100%, more preferably 45% to 60% of the thickness of the low refractive index layer can be used. .

  In the low refractive index layer of the present invention, for the purpose of imparting properties such as antifouling property, water resistance, chemical resistance, and slipping property, a known polysiloxane-based or fluorine-based antifouling agent, slipping agent, etc. are appropriately used. Can be added.

[Formation of each layer]
The coating layer used in the present invention, and if necessary, a hard coat layer, a low refractive index layer, or other layers are coated with a coating solution on a transparent support, heated and dried, and then if necessary. The monomer and curable resin for forming each layer are cured by light irradiation and / or heating. Thereby, each layer is formed.

  Although the coating method of each layer of the film of the present invention is not particularly limited, a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, an extrusion coating method (die coating method) ( U.S. Pat. No. 2,681,294) and known methods such as a micro gravure coating method are used, and among them, the micro gravure coating method and the die coating method are preferably used from the viewpoints of high productivity and coating film uniformity.

―Drying process―
In the present invention, it is important to control the drying process after the coating layer having low moisture permeability is applied in order to bring the residual solvent amount of the transparent substrate on which the coating layer having low moisture permeability is formed into a desired range. .
It is preferable that the coating layer having low moisture permeability is formed through a drying process in which 50% or more of the organic solvent evaporates in 1 to 50 seconds after the application after the application in the drying process after the application. The time for evaporating 50% or more of the solvent is more preferably 1 second to 30 seconds, and further preferably 2 seconds to 15 seconds. If the time during which 50% or more of the organic solvent evaporates is too short, it is not preferable because the film thickness unevenness is difficult to obtain, and if it is too long, the amount of the residual solvent increases, which is not preferable.

1st drying process The drying temperature performs the 1st drying process dried at the drying temperature of 70 degrees C or less until 50% or more of the organic solvent evaporates, and it dries at the drying temperature of 70 degrees C or more and 150 degrees C or less after that. The second drying step is preferably performed, and the first drying step is performed at a drying temperature of 50 ° C. or lower until 50% or more of the organic solvent evaporates, and then the drying is performed at 70 ° C. or higher and 130 ° C. or lower. More preferably, the second drying step is performed at a temperature, and the first drying step is performed at a drying temperature of 40 ° C. or lower until 50% or more of the organic solvent evaporates. More preferably, a second drying step is performed in which drying is performed at a drying temperature of not higher than ° C.
If the drying temperature until 50% or more of the organic solvent evaporates is too high, it is not preferable from the viewpoint of film thickness unevenness, moisture permeability, and the like. Further, if the subsequent drying temperature is too low, the amount of residual solvent increases, which is not preferable, and if it is too high, the transparent substrate is damaged and is not preferable.

  The coating layer may be subjected to heat treatment to increase the crystallinity. A preferable heat treatment temperature is 40 ° C. to 130 ° C., and the heat treatment time can be appropriately determined according to the required crystallinity, but is usually about 5 minutes to 48 hours.

  Furthermore, for the purpose of improving the adhesion between the transparent substrate film and the coating layer, it is more preferable to perform pretreatment such as hydrophilization treatment and uneven treatment on one or both sides of the transparent substrate film as desired. Examples of the pretreatment include corona discharge treatment, glow discharge treatment, chromic acid treatment (wet), saponification treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. Saponification treatment (wet) is particularly preferred.

  In the present invention, these formed coating layers and hard coat layers are allowed to contain an antifouling agent, or are cured by heat or ultraviolet irradiation including a low surface energy curable resin containing fluorine and / or silicon. The antifouling property can be imparted, for example, by forming an antifouling coating layer by laminating an antifouling layer mainly composed of the curable composition to be formed.

  The antifouling agent used in the present invention imparts antifouling properties such as water repellency and oil repellency to the coating layer, such as preparation of a coating solution for forming a coating layer and transparent base film Any coating material may be used as long as there is no inconvenience when it is applied on the surface and water and oil repellency is exhibited on the surface of the antifouling coating layer when the antifouling coating layer is formed. Such a resin includes a cured resin containing fluorine and / or silicon.

[Curable resin containing fluorine and / or silicon]
The curable resin containing fluorine and / or silicon contained in the coating layer or antifouling layer used in the present invention includes a known fluorine curable resin, silicon curable resin, or fluorine and silicon-containing part. A curable resin having a block is mentioned, and a curable resin containing a segment having good compatibility with a resin or metal oxide and a segment containing fluorine or silicon is preferable, and the coating layer or the antifouling layer is obtained. By adding, fluorine or silicon can be unevenly distributed on the surface.

  Specific examples of these curable resins include block copolymers or graft copolymers of fluorine- or silicon-containing monomers and other hydrophilic or lipophilic monomers. Examples of the fluorine-containing monomer include perfluoroalkyl group-containing (meth) acrylic acid esters such as hexafluoroisopropyl acrylate, heptadecafluorodecyl acrylate, perfluoroalkylsulfonamidoethyl acrylate, and perfluoroalkylamidoethyl acrylate. . Examples of the silicon-containing monomer include monomers having a siloxane group by a reaction such as polydimethylsiloxane and (meth) acrylic acid. Hydrophilic or lipophilic monomers include (meth) acrylic acid esters such as methyl acrylate, hydroxyl-containing polyester and (meth) acrylic acid ester at the terminal, hydroxyethyl (meth) acrylate, and polyethylene glycol (meth) acrylic acid Examples include esters.

  Commercially available curable resins include acrylic oligomers having a perfluoroalkyl chain microdomain structure, such as “Defenser MCF-300”, “Defenser MCF-312”, “Defenser MCF-323”, etc. “Megafac F-170”, “Megafac F-173”, “Megafac F-175”, etc. of oligomers containing oily groups, “Megafac F-171”, etc. of oligomers containing perfluoroalkyl groups / hydrophilic groups { As described above, manufactured by Dainippon Ink & Chemicals, Inc., and fluorinated alkyl-based “Modiper F-200” and “Modiper”, which are block polymers of vinyl monomers composed of a segment having excellent surface migration and a segment compatible with the resin. F-220 "," Modiper F-600 "," Modiper F-820 ", etc. "Modiper FS-700" on emissions system, "Modiper FS-710", etc. {above, NOF Corp.} are exemplified.

  In order to provide an antifouling layer on the coating layer, a curable resin having a low surface energy and containing fluorine atoms is preferred. Specifically, JP-A-57-34526 and JP-A-2-19811 are preferred. Examples thereof include a silicon curable resin containing a fluorinated hydrocarbon group and a fluorinated hydrocarbon group-containing polymer described in JP-A-3-17901.

  When producing a polarizing plate using the protective film for polarizing plates of the present invention as at least one of the surface protective films of two polarizing films, the protective film for polarizing plates is opposite to the coating layer. It is preferable to improve the adhesion on the adhesive surface by hydrophilizing the surface of the transparent substrate film, that is, the surface to be bonded to the polarizing film. The hydrophilized surface is effective for improving the adhesiveness with the adhesive layer mainly composed of polyvinyl alcohol. As the hydrophilic treatment, the following saponification treatment is preferably performed. Moreover, also when performing a saponification process as pre-processing before forming a coating layer by this invention, it is preferable to use the following method.

[Saponification]
(1) Method of immersing in alkaline solution This is a technique in which a protective film for polarizing plate is immersed in an alkaline solution under appropriate conditions, and all surfaces having reactivity with alkali on the entire surface of the film are saponified. It is preferable from the viewpoint of cost because it does not require any equipment. The alkaline liquid is preferably a sodium hydroxide aqueous solution. A preferred concentration is 0.5 to 3 mol / L, particularly preferably 1 to 2 mol / L. The liquid temperature of a preferable alkali liquid is 30-75 degreeC, Most preferably, it is 40-60 degreeC.
The combination of the saponification conditions is preferably a combination of relatively mild conditions, but can be set according to the material and configuration of the light scattering film and the antireflection film, and the target contact angle.
After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by immersing in a dilute acid so that the alkaline component does not remain in the film.

By saponification treatment, the surface opposite to the surface having the antiglare layer or antireflection layer of the transparent support is hydrophilized. The protective film for polarizing plate is used by adhering the hydrophilic surface of the transparent support to the polarizing film.
The hydrophilized surface is effective for improving the adhesiveness with the adhesive layer mainly composed of polyvinyl alcohol.
In the saponification treatment, the lower the contact angle with water on the surface of the transparent support opposite to the side having the antiglare layer or the low refractive index layer, the better from the viewpoint of adhesiveness to the polarizing film. At the same time, since it is damaged by alkali from the surface having the antiglare layer and the low refractive index layer to the inside, it is important to set the reaction conditions to the minimum necessary. When the contact angle to water of the transparent support on the opposite surface is used as an index of damage to each layer due to alkali, particularly when the transparent support is triacetylcellulose, preferably 10 to 50 degrees, more preferably Is 30 to 50 degrees, more preferably 40 to 50 degrees. If it is 50 degrees or more, there is a problem in the adhesion to the polarizing film, which is not preferable. On the other hand, if it is less than 10 degrees, the damage is too great, and physical strength is impaired.

(2) Method of applying alkaline solution As a means for avoiding damage to each film in the above-mentioned immersion method, the alkaline solution is applied only to the surface opposite to the surface having the antiglare layer or the low refractive index layer under appropriate conditions. An alkaline solution coating method of coating, heating, washing with water and drying is preferably used. The application in this case means that an alkaline solution or the like is brought into contact only with the surface to be saponified, and in addition to the application, it may be carried out by spraying or contacting a belt containing the solution. Including. By adopting these methods, a separate facility and process for applying an alkaline solution are required, which is inferior to the immersion method (1) from the viewpoint of cost. On the other hand, since the alkali solution contacts only the surface to be saponified, the opposite surface can have a layer using a material that is weak against the alkali solution. For example, vapor deposition films and sol-gel films have various effects such as corrosion, dissolution, and peeling due to alkali solution, so it is not desirable to use the immersion method. Is possible.

  In any of the saponification methods (1) and (2), the film can be unwound from a roll-shaped support and formed after forming each layer. You may carry out by operation of. Furthermore, the polarizing plate can be produced more efficiently than the same operation with a single wafer by continuously performing the bonding step with the polarizing plate comprising the support that has been unwound in the same manner.

(3) Method of protecting antiglare layer or antireflection layer with laminate film and saponifying As in the case of (2), when antiglare layer and / or low refractive index layer is insufficient in resistance to alkaline solution In addition, after forming the final layer, the laminate film is bonded to the surface on which the final layer is formed and then immersed in an alkaline solution to hydrophilize only the side of the triacetyl cellulose opposite to the surface on which the final layer is formed, Thereafter, the laminate film can be peeled off. Even in this method, only the surface opposite to the surface on which the final layer of the triacetyl cellulose film is formed is subjected to the hydrophilization treatment necessary for the polarizing plate protective film without damaging the antiglare layer and the low refractive index layer. be able to. Compared with the method (2), there is an advantage that a laminate film is generated as waste, but a device for applying a special alkaline solution is unnecessary.

(4) Method of immersing in alkaline solution after forming up to antiglare layer Up to antiglare layer is resistant to alkaline solution, but when low refractive index layer is insufficiently resistant to alkaline solution, after forming up to antiglare layer It is also possible to soak both surfaces in an alkali solution to hydrophilize both surfaces, and then form a low refractive index layer on the antiglare layer. Although the manufacturing process becomes complicated, there is an advantage that the interlayer adhesion between the antiglare layer and the low refractive index layer is improved particularly when the low refractive index layer has a hydrophilic group such as a fluorine-containing sol-gel film.

(5) Method of forming a coating on a previously saponified triacetyl cellulose film Saponification is performed by, for example, pre-immersing a triacetyl cellulose film in an alkali solution, and coating is performed directly on one side or through another layer. A layer may be formed. In the case of saponification by dipping in an alkaline solution, interlayer adhesion between the coating layer and the triacetyl cellulose surface hydrophilized by saponification may deteriorate. In such a case, after saponification, only the surface on which the coating layer is to be formed is treated with corona discharge, glow discharge, etc. to remove the hydrophilic surface and then form an antiglare layer or other layer. Can be dealt with. Further, when the antiglare layer or other layers have a hydrophilic group, the interlayer adhesion may be good.

  Below, the polarizing plate using the protective film for polarizing plates of this invention and the liquid crystal display device using this polarizing plate are demonstrated.

(Polarizer)
FIG. 2 is a cross-sectional view showing a configuration in one embodiment of a polarizing plate using the polarizing plate protective film of the present invention.
As shown in FIG. 2, the polarizing plate 5 of the present invention comprises the polarizing plate protective film 1 of the present invention and the polarizing plate protective film 7 on the side opposite to the polarizer 6.
2A and 2B, the polarizing plate 5 of the present invention is bonded to the polarizer 6 on the surface opposite to the coating layer 3.
2C and 2D, the polarizing plate 5 of the present invention has the coating layer 3 bonded to the polarizer 6.
The polarizing plate protective film 4 on the opposite side is not particularly limited, and various substrates such as a substrate film made of cellulose acylates, a cycloolefin film, a polycarbonate film, and a thermoplastic resin film containing a lactone ring-containing polymer. A film is used. From the viewpoint of productivity, a base film made of cellulose acylates having a low moisture permeability and having no coating layer is preferable.

<Preparation of polarizing film>
The protective film for polarizing plates of this invention comprises a polarizing plate by bonding together at least 1 surface of a polarizer. The moisture permeability of the polarizing plate to be bonded to the other surface of the polarizer is not particularly limited, but it is preferable to bond a polarizing plate protective film having a moisture permeability of 700 to 3,000 g / m ² · day, more preferably. 1,000 to 1,700 g / m ² · day. Usually used TAC is preferably used.
A normal cellulose acetate film may be used, but a cellulose acetate film manufactured by a solution casting method and stretched in the width direction in the form of a roll film at a stretching ratio of 10 to 100% may be used.
Furthermore, in the polarizing plate of the present invention, one side is the protective film for polarizing plate of the present invention, whereas the other protective film is an optical compensation film having an optically anisotropic layer made of a liquid crystalline compound. Good.
In the polarizing plate of the present invention, one side is the protective film for polarizing plate of the present invention, whereas the other protective film is a film having Re of 0 to 10 nm and Rth of -20 to 20 nm (for example, Japanese Patent Laid-Open No. 2005-301227, paragraph number [0095]).

  Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film.

Of the two protective films of the polarizer, the film other than the polarizing plate protective film of the present invention is preferably an optical compensation film having an optical compensation layer comprising an optically anisotropic layer. The optical compensation film (retardation film) can improve the viewing angle characteristics of the liquid crystal display screen.
A known film is used as the optical compensation film, but the optical compensation film described in JP-A-2001-100042 is preferable in terms of widening the viewing angle.

  When the polarizing plate protective film of the present invention is used together with a liquid crystal display device or the like, it is preferably disposed on the viewing side opposite to the liquid crystal cell.

(Image display device)
<Liquid crystal display device>
The film and polarizing plate of the present invention can be advantageously used for an image display device such as a liquid crystal display device, and is preferably used for the outermost layer of the display.
The liquid crystal display device has a liquid crystal cell and two polarizing plates arranged on both sides thereof, and the liquid crystal cell carries a liquid crystal between two electrode substrates. Furthermore, one optically anisotropic layer may be disposed between the liquid crystal cell and one polarizing plate, or two optically anisotropic layers may be disposed between the liquid crystal cell and both polarizing plates.

3A and 3B are cross-sectional views showing the configuration of an embodiment of a liquid crystal display device using the polarizing plate of the present invention.
The liquid crystal display device 8 of the present invention shown in FIGS. 3A to 3B includes the polarizing plate 5 and the liquid crystal cell 9 of the present invention. The polarizing plate 5 of the present invention is preferably used on both sides as shown in FIGS. In the polarizing plate of the present invention, it is preferable that the opposite protective film 7 side is attached to the liquid crystal cell via an adhesive.

The hard coat layer may be used only on the viewer-side surface of the liquid crystal display device, but it is particularly preferable to use it on both sides in order to achieve curl balance of the entire cell when the temperature and humidity change.
In order to improve image visibility and image quality, at least the layer having a hard coat property of the protective film for polarizing plate used on the viewer-side surface should be imparted with scattering properties and / or reduced to a higher level. It is preferable to provide a refractive index layer, and in terms of curl balance, imparting scattering properties to the layers having a hard coat property of the polarizing plate protective film on both sides of the liquid crystal display device, and / or an antireflection layer thereon. It is also preferable to use the provision of

As the protective film 4 on the opposite side of the polarizing plate of the present invention, an optical compensation film that can improve contrast and color when the front direction and viewing angle of various liquid crystal modes are changed is also preferably used. It is also preferable that the film is a base film in which an optical compensation layer is formed on the base film.
Moreover, it is another preferable form that an optical compensation film is attached on the opposite protective film via an adhesive.

  The liquid crystal cell is preferably in TN mode, VA mode, OCB mode, IPS mode, or ECB mode.

<TN mode>
In a TN mode liquid crystal cell, rod-like liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and are twisted and aligned at 60 to 120 °.
The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.

<VA mode>
In a VA mode liquid crystal cell, rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied.
The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. Hei 2-). 176625) (2) Liquid crystal cell (SID97, Digest of Tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (for MVA mode) in order to enlarge the viewing angle. ), (3) A liquid crystal cell in a mode (n-ASM mode) in which rod-like liquid crystalline molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary collections 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

<OCB mode>
The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in substantially opposite directions (symmetrically) at the upper and lower portions of the liquid crystal cell. US Pat. No. 4,583,825, No. 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.

<IPS mode>
The IPS mode liquid crystal cell is a type in which a nematic liquid crystal is switched by applying a lateral electric field. IDRC (Asia Display '95), p. 577-580 and p. 707-710.

<ECB mode>
In the ECB mode liquid crystal cell, rod-like liquid crystalline molecules are substantially horizontally aligned when no voltage is applied. The ECB mode is one of the liquid crystal display modes having the simplest structure, and is described in detail in, for example, Japanese Patent Application Laid-Open No. 5-203946.

<Brightness enhancement film>
As the brightness enhancement film, a polarization conversion element having a function of separating light emitted from a light source (backlight) into transmitted polarized light, reflected polarized light, or scattered polarized light is used. Such a brightness enhancement film can improve the output efficiency of linearly polarized light by using retroreflected light from reflected polarized light or scattered polarized light backlight.
An example is an anisotropic reflective polarizer. An anisotropic reflective polarizer includes an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction. An example of the anisotropic multi-thin film is DBM manufactured by 3M (see, for example, JP-A-4-268505).
An example of the anisotropic reflective polarizer is a composite of a cholesteric liquid crystal layer and a λ / 4 plate. An example of such a composite is PCF manufactured by Nitto Denko (see JP-A-11-231130, etc.).
An example of the anisotropic reflective polarizer is a reflective grid polarizer. As the reflective grid polarizer, a metal grid reflective polarizer (see US Pat. No. 6,288,840, etc.) that finely processes metal to produce reflected polarized light even in the visible light region, and metal fine particles in a polymer matrix. Examples thereof include those stretched by being inserted (see JP-A-8-184701, etc.).

Moreover, an anisotropic scattering polarizer is mentioned. An example of the anisotropic scattering polarizer is DRP manufactured by 3M (see US Pat. No. 5,825,543).
Furthermore, there is a polarizing element that can perform polarization conversion in one pass. For example, the one using smectic C ^* can be mentioned (see JP 2001-201635 A). An anisotropic diffraction grating is used.
The polarizing plate of the present invention can be used together with a brightness enhancement film. In the case of using the brightness enhancement film, it is more preferable that the polarizing plate and the brightness enhancement film are in close contact with each other in order to prevent moisture from entering the polarizing plate and suppress light leakage. The adhesive for bonding the polarizing plate and the brightness enhancement film is not particularly limited. For example, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyvinyl ether, vinyl acetate / vinyl chloride copolymer, modified polyolefin, epoxy-based, fluorine-based, natural rubber, synthetic rubber and other rubber-based polymers Can be appropriately selected and used. In particular, it is preferable to use a material that is excellent in optical transparency, exhibits appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and is excellent in weather resistance, heat resistance, and the like.

<Touch panel>
The film of the present invention can be applied to touch panels described in JP-A-5-127822 and JP-A-2002-48913.

<Organic EL device>
The film of the present invention can be used as a substrate (base film) such as an organic EL element or a protective film.
When the film of the present invention is used for an organic EL device or the like, JP-A-11-335661, JP-A-11-335368, JP-A-2001-192651, JP-A-2001-192652, JP-A-2001-192653, JP-A-2001-335776, JP-A-2001-247859, JP-A-2001-181616, JP-A-2001-181617, JP-A-2002-181816, JP-A-2002-181617, JP-A-2002-056776, etc. The contents described in each publication can be applied. Moreover, it is preferable to use together with the content of each gazette of Unexamined-Japanese-Patent No. 2001-148291, Unexamined-Japanese-Patent No. 2001-221916, and Unexamined-Japanese-Patent No. 2001-231443.

  Hereinafter, the present invention will be described more specifically by way of examples. However, the embodiments of the present invention are not limited to these examples.

<Adjustment of coating solution for coating layer>
<< Preparation of Coating Layer Coating Solution 1 >>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a coating solution 1 for coating layer.

[Composition of Coating Layer Coating Liquid 1]
-Chlorine-containing polymer: R204
{"Saran Resin R204" manufactured by Asahi Kasei Life & Living Co., Ltd.} 10g
・ 72 g of tetrahydrofuran
・ Toluene 18g
・ Ciba Specialty Chemicals "Chinubin 928" 0.3g

<< Preparation of Coating Layer Coating Solution 2 >>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a coating layer coating solution 2.

[Coating layer coating solution 2]
-Chlorine-containing polymer: R204
("Saran Resin R204" manufactured by Asahi Kasei Life & Living Co., Ltd.) 10g
・ N-methylpyrrolidone 72g
・ Toluene 18g
・ Ciba Specialty Chemicals "Chinubin 928" 0.3g

<< Preparation of coating solution 3 for coating layer >>
The following composition was put into a mixing tank, stirred to dissolve each component, and a coating layer coating solution 3 was prepared.

[Coating layer coating solution 3]
-Chlorine-containing polymer: R204
・ {Asahi Kasei Life & Living "Saran Resin R204"} 10g
・ Cyclohexanone 72g
・ Toluene 18g
・ Ciba Specialty Chemicals "Chinubin 928" 0.3g

<< Preparation of Coating Layer Coating Liquid 4 >>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a coating layer coating solution 4.

[Coating layer coating solution 4]
-Chlorine-containing polymer: F216
{"Saran Resin F216" manufactured by Asahi Kasei Life & Living Co., Ltd.} 10g
・ 72 g of tetrahydrofuran
・ Toluene 18g
・ Ciba Specialty Chemicals "Chinubin 928" 0.3g

<< Preparation of Coating Layer Coating Liquid 5 >>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a coating layer coating solution 5.

[Coating layer coating solution 5]
-Chlorine-containing polymer: F216
{"Saran Resin F216" manufactured by Asahi Kasei Life & Living Co., Ltd.} 10g
・ Tetrahydrofuran 22g
・ Toluene 68g
・ Ciba Specialty Chemicals "Chinubin 928" 0.3g

<< Preparation of coating solution 6 for coating layer >>
The following composition was put into a mixing tank, stirred to dissolve each component, and a coating layer coating solution 6 was prepared.

[Coating layer coating solution 6]
・ TOPAS 6g made by Polyplastics Co., Ltd.
・ Coronate L 0.5g
・ 85 g of tetrahydrofuran
・ Toluene 9g

<< Preparation of coating solution 7 for coating layer >>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a coating layer coating solution 7.

[Coating layer coating solution 7]
・ TOPAS 6g made by Polyplastics Co., Ltd.
・ Coronate L 0.5g
・ 85g of n-methylpyrrolidone
・ Toluene 9g

<< Synthesis of Perfluoroolefin Copolymer (1) >>
Into an autoclave with a stirrer made of stainless steel having an internal volume of 100 ml, 40 ml of ethyl acetate, 14.7 g of hydroxyethyl vinyl ether and 0.55 g of dilauroyl peroxide were charged, and the inside of the system was deaerated and replaced with nitrogen gas. Further, 25 g of hexafluoropropylene (HFP) was introduced into the autoclave and the temperature was raised to 65 ° C. The pressure when the temperature in the autoclave reached 65 ° C. was 0.53 Mpa (5.4 kg / cm ² ). The temperature was maintained and the reaction was continued for 8 hours. When the pressure reached 0.31 MPa (3.2 kg / cm ² ), the heating was stopped and the mixture was allowed to cool.
When the internal temperature dropped to room temperature, unreacted monomers were driven out, the autoclave was opened, and the reaction solution was taken out.
The obtained reaction solution was poured into a large excess of hexane, and the polymer was precipitated by removing the solvent by decantation.
Further, this polymer was dissolved in a small amount of ethyl acetate and reprecipitated twice from hexane to completely remove the residual monomer. After drying, 28 g of polymer was obtained. Next, 20 g of the polymer was dissolved in 100 ml of N, N-dimethylacetamide, and 11.4 g of acrylic acid chloride was added dropwise under ice cooling, followed by stirring at room temperature for 10 hours. Ethyl acetate was added to the reaction solution, washed with water, the organic layer was extracted and concentrated, and the resulting polymer was reprecipitated with hexane to obtain 19 g of a perfluoroolefin copolymer (1) represented by the following structural formula. The resulting polymer had a refractive index of 1.421.

<< Preparation of Coating Layer Coating Liquid 8 >>
The following composition was put into a mixing tank, stirred to dissolve each component, and a coating layer coating solution 8 was prepared.

[Coating layer coating solution 8]
・ Perfluoroolefin copolymer (1) 19g
・ DPHA 1g
・ Irgacure 907 0.6g made by Ciba Specialty Chemicals
・ Methyl ethyl ketone 56g
・ Methyl isobutyl ketone 24g

<< Preparation of coating solution 9 for coating layer >>
The following composition was put into a mixing tank and stirred to dissolve each component, thereby preparing a coating layer coating solution 9.

[Coating layer coating solution 9]
・ Perfluoroolefin copolymer (1) 19g
・ DPHA 1g
・ Irgacure 907 0.6g made by Ciba Specialty Chemicals
・ N-Methylpyrrolidone 56g
・ Methyl isobutyl ketone 24g

Example 1
<Preparation of protective film for polarizing plate>
An 80 μm-thick triacetyl cellulose film (TAC-TD80U, manufactured by FUJIFILM Corporation) is unwound in a roll form, and the coating solution 1 for the coating layer is applied on the backup roll using a coater having a slot die. It was extruded and applied directly onto the acetylcellulose film surface. After coating at a conveyance speed of 30 m / min, the protective film for polarizing plate of Example 1 in which a coating layer having a film thickness of 1.5 μm was formed by drying based on the following drying condition 1 was produced.

<< Drying condition 1 >>
Immediately after application, a windshield plate was installed in parallel to the application surface, and no dry air was blown. After 1 second from the coating, room temperature air with a wind speed of 2 m / second was applied for 20 seconds and then dried at 100 ° C. for 45 seconds.

<Preparation of protective film for polarizing plate>
The protective film for polarizing plates of Example 2 in which a coating layer having a film thickness of 1.5 μm was formed under the same conditions as in Example 1 except that drying was performed based on the following drying conditions 2 instead of the drying conditions 1 in Example 1. Was made.

<< Drying condition 2 >>
Immediately after application, a windshield plate was installed in parallel to the application surface, and no dry air was blown. After 7 seconds from the coating, room temperature air with a wind speed of 2 m / second was applied for 20 seconds and then dried at 100 ° C. for 45 seconds.

(Example 3)
<Preparation of protective film for polarizing plate>
A protective film for a polarizing plate of Example 3 in which a coating layer having a film thickness of 1.5 μm was formed under the same conditions as in Example 1 except that drying was performed based on the following drying condition 3 instead of drying condition 1 in Example 1. Was made.

<< Drying condition 3 >>
Immediately after application, a windshield plate was installed in parallel to the application surface, and no dry air was blown. From 45 seconds after coating, room temperature wind at a wind speed of 2 m / second was applied for 20 seconds, and then dried at 100 ° C. for 45 seconds.

Example 4
<Preparation of protective film for polarizing plate>
The polarizing plate of Example 4 in which a coating layer having a film thickness of 1.5 μm was formed under the same conditions as in Example 2 except that coating solution 4 for coating layer was used instead of coating solution 1 for coating layer in Example 2. A protective film was prepared.

(Example 5)
<Preparation of protective film for polarizing plate>
The polarizing plate of Example 5 in which a coating layer having a thickness of 3.0 μm was formed under the same conditions as in Example 2 except that coating solution 6 for coating layer was used instead of coating solution 1 for coating layer in Example 2. A protective film was prepared.

(Example 6)
<Preparation of protective film for polarizing plate>
An 80 μm-thick triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd.) is unwound in a roll form, and the coating solution 8 for the coating layer is applied on the backup roll using a coater having a slot die. It was extruded and applied directly onto the acetylcellulose film surface.
After coating at a transfer speed of 30 m / min, the coating was dried based on the above drying condition 1, and using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) under a nitrogen purge, an irradiation amount of 200 mJ / It was irradiated with ultraviolet rays cm ² performs hardened, to prepare a polarizing plate protective film of example 6 to form a coating layer having a thickness of 20 [mu] m.

(Comparative Example 1)
<Preparation of protective film for polarizing plate>
A protective film for a polarizing plate of Comparative Example 1 in which a coating layer having a film thickness of 1.5 μm was formed under the same conditions as in Example 1 except that drying was performed based on the following drying conditions 4 instead of drying conditions 1 in Example 1. Was made.

<< Drying condition 4 >>
Immediately after application, a windshield plate was installed in parallel with the application surface, and no drying air was blown for 70 seconds. After 70 seconds from the coating, room temperature wind at a wind speed of 2 m / second was applied for 20 seconds, and then dried at 100 ° C. for 45 seconds.

(Comparative Example 2)
<Preparation of protective film for polarizing plate>
A protective film for a polarizing plate of Comparative Example 2 in which a coating layer having a thickness of 1.5 μm was formed under the same conditions except that drying was performed based on the following drying condition 5 instead of the drying condition 1 in Example 1.

<< Drying condition 5 >>
Immediately after application, a windshield plate was installed in parallel to the application surface, and no dry air was blown. From 90 seconds after coating, room temperature wind at a wind speed of 2 m / second was applied for 20 seconds, and then dried at 100 ° C. for 45 seconds.

(Comparative Example 3)
<Preparation of protective film for polarizing plate>
A protective film for a polarizing plate of Comparative Example 3 in which a coating layer having a film thickness of 1.5 μm was formed under the same conditions as in Example 1 except that drying was performed based on the following drying conditions 6 instead of the drying conditions 1 in Example 1. Was made.

<< Drying condition 6 >>
Immediately after application, a windshield plate was installed in parallel to the application surface, and no dry air was blown. One second after application, 80 ° C. wind with a wind speed of 2 m / second was applied for 20 seconds, and then dried at 100 ° C. for 45 seconds.

(Comparative Example 4
<Preparation of protective film for polarizing plate>
A protective film for a polarizing plate of Comparative Example 4 in which a coating layer having a film thickness of 1.5 μm was formed under the same conditions as in Example 1 except that drying was performed based on the following drying conditions 7 instead of the drying conditions 1 in Example 1. Was made.

<< Drying condition 7 >>
Immediately after application, a windshield plate was installed in parallel to the application surface, and no dry air was blown. From 1 second after coating, a room temperature wind of 2 m / sec was applied for 20 seconds, and then dried at room temperature for 45 seconds.

(Comparative Example 5)
<Preparation of protective film for polarizing plate>
A protective film for a polarizing plate of Comparative Example 5 in which a coating layer having a thickness of 1.5 μm was formed under the same conditions as in Example 1 except that drying was performed based on the following drying conditions 8 instead of the drying conditions 1 in Example 1. Was made.

<< Drying condition 8 >>
Immediately after application, a windshield plate was installed in parallel to the application surface, and no dry air was blown. After 1 second of coating, room temperature wind at a wind speed of 2 m / sec was applied for 20 seconds and then dried at 150 ° C. for 45 seconds.

(Comparative Example 6)
<Preparation of protective film for polarizing plate>
The polarizing plate of Comparative Example 6 in which a coating layer having a thickness of 1.5 μm was formed under the same conditions as in Example 2 except that coating solution 2 for coating layer was used instead of coating solution 1 for coating layer in Example 2. A protective film was prepared.

(Comparative Example 7)
<Preparation of protective film for polarizing plate>
A polarizing plate of Comparative Example 7 in which a coating layer having a thickness of 1.5 μm was formed under the same conditions as in Example 2 except that coating solution 3 for coating layer was used instead of coating solution 1 for coating layer in Example 2. A protective film was prepared.

(Comparative Example 8)
<Preparation of protective film for polarizing plate>
For the polarizing plate of Comparative Example 8 in which a coating layer having a film thickness of 1.5 μm was formed under the same conditions as in Example 2 except that coating liquid 5 for coating layer was used instead of coating liquid 1 for coating layer in Example 2. A protective film was prepared.

(Comparative Example 9)
<Preparation of protective film for polarizing plate>
The polarizing plate of Comparative Example 9 in which a coating layer having a thickness of 3.0 μm was formed under the same conditions as in Example 2 except that the coating solution 7 for coating layer was used instead of the coating solution 1 for coating layer in Example 2. A protective film was prepared.

(Comparative Example 10)
<Preparation of protective film for polarizing plate>
Protection for polarizing plate of Comparative Example 10 in which a coating layer having a thickness of 30 μm was formed under the same conditions as in Example 5 except that coating solution 9 for coating layer was used instead of coating solution 8 for coating layer in Example 5. A film was prepared.

  The “residual solvent amount”, “moisture permeability”, and “light resistance” of the protective films for polarizing plates of Examples 1 to 6 and Comparative Examples 1 to 10 prepared as described above were measured as follows. The “adhesion” was evaluated based on the following evaluation criteria. The results are shown in Table 2.

<< Residual solvent amount >>
The determination of the residual organic solvent in the film in the present invention was performed using gas chromatography (GC) equipped with a flame ionization detector (FID). This will be described in detail below.
The GC device used was a GC-2010 model manufactured by Shimadzu Corporation.
For the column, DB-624 (length 60 m, diameter 0.32 mm, film thickness 1.8 μm) manufactured by J & W was used.
Preparation of a measurement sample is performed by first adding 1.5 g of a film sample to be measured to 40 g of a solvent for dissolving a transparent base material and a coating layer in a screw cap bottle, and stoppering at 60 rpm at room temperature for 12 hours. As a result, the remaining organic solvent in the sample was extracted into the solvent for dissolution to prepare a sample solution.
In the case of a transparent substrate composed of cellulose acylates which is a transparent substrate preferable for the present invention, it is most preferable to use n-methylpyrrolidone.
0.5 g of the prepared sample solution was weighed and diluted by adding 2.5 g of n-methylpyrrolidone.
In the analysis, this solution was subjected to predetermined conditions (injector temperature 230 ° C., detector temperature 250 ° C., column temperature 80 ° C. → 4 ° C./min temperature increase → 230 ° C. 5 min hold, carrier gas He 90 KPa, split ratio 1 / 1 μl was injected into the GC apparatus of 20). The area value of the detected peak was converted from the area value of the separately prepared 3 inspection standard curve.
In the present invention, the residual amount of each solvent used in the above method was measured, and the total value was used as the residual amount.

<< Moisture permeability >>
The measurement method of moisture permeability is "Polymer Physical Properties II" (Polymer Experiment Course 4, Kyoritsu Shuppan), pages 285-294: Measurement of vapor permeation (mass method, thermometer method, vapor pressure method, adsorption amount method) The film sample of 70 mmφ according to the present invention was conditioned at 60 ° C. and 95% RH for 24 hours, and using a moisture permeable cup according to JIS Z-0208, moisture permeability = The amount of water per unit area (g / m ² ) was calculated as mass after humidity control-mass before humidity control. The moisture permeability value was not corrected for a blank cup without a hygroscopic agent.

<< Evaluation of adhesion >>
The adhesion between the film layers or between the support and the coating layer was evaluated by the following method.
Nitto Denko Co., Ltd. Polyester adhesive tape made by cutting a total of 100 square squares on the surface having the coating layer with a cutter knife in a grid pattern with 11 vertical and 11 horizontal cuts at 1 mm intervals. (NO.31B) is pressure-bonded, tested for 24 hours and then peeled off, and the presence or absence of peeling is visually observed.

[Evaluation criteria]
○: No peeling △: Some peeling, but no problem in practical use ×: There is peeling on the entire surface

<< Light resistance test >>
Using a metering weather meter MV3000 manufactured by Suga Test Instruments Co., Ltd., irradiance 530 ± 25 W / m ² (wavelength 310 to 400 nm), test chamber temperature 40 ± 5 ° C., black panel temperature 60 ± 5 ° C., relative humidity 50 ± Under the condition of 10%, the light irradiation treatment was performed under the emphasis condition in which the sample attached on the SUS plate was irradiated with light for 1 hour.
Evaluation was performed using a transmitted light color change amount (CIE 1976 L ^* a ^* b ^* color difference ΔE ^* ab value in the color space) calculated by the following mathematical formula (2). L ^* , a ^* , and b ^* are measured using a spectrophotometer (using a UV3100 integrating sphere manufactured by JASCO Corporation) in a wavelength region of 250 to 800 nm at an incident angle of 2 degrees. From the spectral reflectance, The color L ^* , a ^* , b ^* of the transmitted light of the CIE standard light source C was calculated. When ΔE ^* ab was 2 or more, yellowing of the transmitted light was strong and it was a level to be worried about.
ΔE ^* ab = [(ΔL ^* ) 2+ (Δa ^* ) 2+ (Δb ^* ) 2] 1/2 Equation (2)
ΔL ^* = L1 ^* −L2 ^*
Δa ^* = a1 ^* −a2 ^*
Δb ^* = b1 ^* −b2 ^*
(In the above formula (2), L1 ^* , a1 ^* , b1 ^* , L2 ^* , a2 ^* , and b2 ^* indicate the color of the transmitted light of the CIE standard light source C of the protective film for polarizing plate, CIE1976L ^* a ^*. This is expressed in terms of L ^* value, a ^* value, and b ^* value in the b ^* color space, and L1 ^* , a1 ^* , and b1 ^* are protections for the polarizing plate before the light resistance test is performed. L ^* value, a ^* value, and b ^* value of the film are represented, and L2 ^* , a2 ^* , and b2 ^* are L ^* value and a ^* value of the protective film for polarizing plate after the light resistance test is performed. , And b ^* values.)

<< Measurement of film thickness >>
The cross section of the polarizing plate protective film is cut using a microtome, and the cross section is observed in a reflected electron mode using a scanning electron microscope (S-570, manufactured by Hitachi, Ltd.). The layer thickness was determined.
Further, in order to confirm the film thickness distribution of the coating layer, the film thickness was determined at intervals of 20 cm in both the width direction and the longitudinal direction, and the variation with respect to the average film thickness was determined.

As shown in Table 2, it was recognized that the protective films for polarizing plates of Examples 1 to 6 have a small amount of residual solvent, low moisture permeability, and excellent adhesion and light resistance.
Moreover, the protective film for polarizing plates of the comparative example 3 had a rough surface in the form of a cocoon skin, and there was a problem in the surface state, and performance evaluation was not performed.
In particular, Comparative Example 4 was not dried and was not dried, so performance evaluation was not performed.
In Comparative Example 5, the transparent base material was damaged by heat, wrinkles were severe, there was a problem in the surface condition, and performance evaluation was not performed.
All the film thickness distributions of the coating layers of the protective films for polarizing plates of Examples 1 to 6 were ± 10% or less, which was good.
Further, the triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd.) having a thickness of 80 μm without applying a coating layer has a moisture permeability of about 1,400 g / m ² · day, and for the polarizing plate of the present invention. The protective film had no barrier property.

<Measurement of solvent evaporation ratio>
The time required for evaporating 50% or more of the organic solvent in the first drying step of each polarizing plate protective film was measured. The measurement method was as follows: 50 seconds after coating, the coating film was scraped, the mass (W ₀ ) of the scratched coating film was measured, then dried at 100 ° C. for 30 minutes, and the solid content after drying ( W ₁ ) was measured, and the solvent evaporation ratio was determined from the following mathematical formula (4).
In the protective films for polarizing plates of Examples 1 to 6, 50% by mass or more of the initial solvent amount is evaporated, whereas the protective films for polarizing plates of Comparative Examples 1 and 2 and Comparative Examples 6 to 10 are used. All of them had an evaporation amount of less than 50%.
Moreover, although the protective film for polarizing plates of Comparative Examples 3 to 4 all had an evaporation amount of 50% or more, the protective film for polarizing plate of Comparative Example 3 had a high initial drying temperature, and the polarizing plate of Comparative Example 4 The protective film for use was not heated and dried in the latter half, and the polarizing plate protective film of Comparative Example 5 had a too high heating and drying temperature in the latter half, and any usable coating film could not be formed.
Solvent evaporation ratio = ((W ₁ / R) −W ₀ ) / ((W ₁ / R) −W ₁ ) (4)
W ₀ : Mass of coating film scraped off (g)
W ₁ : Mass of solid content after drying (g)
R: Solid content concentration (mass%) in the coating solution

  When the solvent evaporation ratio was measured by the same method as above except that the scraping time of the coating film was changed to 15 seconds, Examples 1, 2, and 4-6 were all 50% by mass or more of the initial solvent amount. The evaporation amount of all the protective films for polarizing plates of Example 3 was less than 50%.

(Examples 7 to 12)
A protective film for a polarizing plate with a hard coat layer was produced by the method described below.

<Preparation of coating solution for hard coat layer>
<< Preparation of Sol Solution a >>
In a 1,000 ml reaction vessel equipped with a thermometer, a nitrogen inlet tube and a dropping funnel, 187 g (0.80 mol) of acryloxyoxypropyltrimethoxysilane, 27.2 g (0.20 mol) of methyltrimethoxysilane, 320 g of methanol ( 10 mol) and 0.06 g (0.001 mol) of KF were added, and 15.1 g (0.86 mol) of water was slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then heated and stirred for 2 hours under methanol reflux. Then, 120 g of sol liquid a was obtained by depressurizingly distilling a low boiling point and further filtering. As a result of GPC measurement of the substance thus obtained, the mass average molecular weight was 1,500, and among the components higher than the oligomer component, the component having a molecular weight of 1,000 to 20,000 was 30%.
Moreover, from the measurement result of ¹ H-NMR, the structure of the obtained substance was a structure represented by the following general formula.

Furthermore, the condensation rate α as determined by ²⁹ Si-NMR was 0.56. From this analysis result, it was found that the silane coupling agent sol was mostly composed of a linear structure.
From the gas chromatography analysis, the raw material acryloxypropyltrimethoxysilane had a residual rate of 5% or less.

  The following composition was put into a mixing tank, stirred to dissolve each component, and filtered through a polypropylene filter having a pore size of 30 μm to prepare a hard coat layer coating solution 1.

[Composition of coating liquid 1 for hard coat layer]
・ PET-30 46.0g
・ Irgacure 184 1.7g
・ MX-600 (30%) 28.6g
・ FP-13 0.06g
・ Sol solution a 7.0g
・ MiBK (methyl isobutyl ketone) 13.0 g
・ MEK (methyl ethyl ketone) 6.0 g

The compounds used are shown below.
PET-30: A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate [manufactured by Nippon Kayaku Co., Ltd.]
・ Irgacure 184: Polymerization initiator [Ciba Specialty Chemicals Co., Ltd.]
MX-600: PMMA particles having an average particle diameter of 6 μm [refractive index: 1.49, manufactured by Soken Chemical Co., Ltd., 30% MIBK dispersion, used after dispersion for 20 minutes at 10,000 rpm with a Polytron disperser]
FP-13: Fluorine-based surface modifier as shown below

<Coating of hard coat layer>
The protective film for polarizing plates of Examples 1 to 6 was unrolled in a roll form, and the coating liquid 1 for hard coat layer was applied as an undercoat layer 2 for the protective film for polarizing plate on a backup roll using a coater having a slot die. Extruded directly onto top and applied. After coating at a transfer speed of 30 m / min, drying at 30 ° C. for 15 seconds and 90 ° C. for 20 seconds, and further using a 160 W / cm air-cooled metal halide lamp (made by Eye Graphics Co., Ltd.) under a nitrogen purge. The coating layer is cured by irradiating with an ultraviolet ray with an irradiation amount of 90 mJ / cm ² to form a hard coating layer having an antiglare property with a thickness of 9.0 μm and wound, with the hard coating layer of Examples 7 to 12 A protective film for a polarizing plate was produced.

<Evaluation of protective film for polarizing plate with hard coat layer>
About the protective film for polarizing plates obtained by Examples 7-12, "integral reflectance", "specular reflectance", and "pencil hardness" are measured as follows, and "anti-glare property" is evaluated according to the following evaluation criteria. Based on the evaluation. The results are shown in Table 3.

<< Measurement of integral reflectance >>
The back side of the film was roughened with sandpaper, then treated with black ink, and the back side was removed, and the surface side was 380 to 780 nm using a spectrophotometer (manufactured by JASCO Corporation). In the region, the integrated spectral reflectance at an incident angle of 5 ° was measured. The arithmetic average value of the integrated reflectance of 450 to 650 nm was used for the result.

<< Measurement of specular reflectance >>
The back side of the film was roughened with sandpaper, then treated with black ink, and the back side was removed, and the surface side was 380 to 780 nm using a spectrophotometer (manufactured by JASCO Corporation). In the region, the specular spectral reflectance at an incident angle of 5 ° was measured. The arithmetic average value of the specular reflectance of 450-650 nm was used for the result.

<< Measurement of hardness >>
[Measurement of pencil hardness]
The hardness of the film of the present invention was evaluated by a pencil hardness test according to JIS-K5400.

<< Anti-Glare >>
The degree of reflection of the fluorescent lamp when the exposed fluorescent lamp (8,000 cd / m ² ) without a louver is projected from an angle of 10 degrees on the obtained liquid crystal television and observed from the direction of −10 degrees is as follows. It was evaluated with.

[Evaluation criteria]
○: The outline of the fluorescent lamp is not blurred.
X: The outline of the fluorescent lamp is reflected and is worrisome.

  As shown in Table 3, it was recognized that the protective film for polarizing plates with a hard-coat layer obtained by Examples 7-12 was excellent in anti-glare property and hardness.

(Examples 13 to 18)
The protective film for polarizing plates with a low refractive index layer was produced by the method described below.

<Preparation of dispersion A>
Hollow silica fine particle sol (Isopropyl alcohol silica sol, average particle diameter 60 nm, shell thickness 10 nm, silica concentration 20% by mass, silica particle refractive index 1.31, prepared by changing the size according to Preparation Example 4 of JP-A-2002-79616 ) After adding 30 g of acryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.5 g of diisopropoxyaluminum ethyl acetate to 500 g, 9 g of ion-exchanged water was added. After reacting at 60 ° C. for 8 hours, the mixture was cooled to room temperature, and 1.8 g of acetylacetone was added. While adding cyclohexanone to 500 g of this dispersion so that the content of silica was almost constant, solvent substitution by vacuum distillation was performed. There was no generation of foreign matter in the dispersion, and the viscosity when the solid content concentration was adjusted to 20% by mass with cyclohexanone was 5 mPa · s at 25 ° C. When the residual amount of isopropyl alcohol in the obtained dispersion A was analyzed by gas chromatography, it was 1.5%.

<Preparation of sol liquid b>
A stirrer, a reactor equipped with a reflux condenser, 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.), 3 parts of diisopropoxyaluminum ethyl acetoacetate were added and mixed. Thereafter, 30 parts of ion-exchanged water was added and reacted at 60 ° C. for 4 hours, and then cooled to room temperature to obtain a sol solution b. The mass average molecular weight was 1,600, and among the components higher than the oligomer component, the component having a molecular weight of 1,000 to 20,000 was 100%. Further, from the gas chromatography analysis, the raw material acryloyloxypropyltrimethoxysilane did not remain at all.

<Preparation of coating solution 1 for low refractive index layer>
Ethylenically unsaturated group-containing fluorine-containing polymer (fluorine polymer (A-1) described in Production Example 3 of JP-A-2005-89536) 45.0 g as a solid content is dissolved in 500 g of methyl isobutyl ketone, and dispersion A 195 parts by mass (silica + 39.0 parts by mass as surface treatment agent solids), colloidal silica dispersion (silica, MEK-ST particle size difference, average particle size 45 nm, solid content concentration 30%, Nissan Chemical ( Co., Ltd.) 30.0 parts by mass (9.0 parts by mass as solids), sol liquid b 17.0 parts by mass (5.0 parts by mass as solids), PM980M (photopolymerization initiator, manufactured by Wako Pure Chemical Industries, Ltd.) 2.0 parts by weight were added. A coating solution 1 for low refractive index was prepared by diluting with methyl ethyl ketone so that the solid content concentration of the entire coating solution was 6% by mass. The refractive index of the layer formed with this coating solution was 1.38.

<Coating of low refractive index layer>
The protective film for polarizing plates with hard coat layers of Examples 7 to 12 was unwound in a roll form, and the coating liquid 1 for the low refractive index layer was applied to the protective film for polarizing plates on the backup roll using a coater having a slot die. The hard coat layer was applied directly onto the surface on which the hard coat layer was applied. After drying at 120 ° C. for 150 seconds and further drying at 140 ° C. for 8 minutes, an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) with 240 W / cm in an atmosphere with an oxygen concentration of 0.1% by nitrogen purge is used. Then, an ultraviolet ray having an irradiation amount of 300 mJ / cm ² was irradiated to form a low refractive index layer having a thickness of 100 nm, and wound to prepare protective films for polarizing plates with refractive index layers of Examples 13 to 18.

  About the protective film for polarizing plates with a low refractive index layer obtained by Examples 13-18, "integral reflectivity", "specular reflectivity", and "pencil hardness" are measured like Example 7-12. In addition, “antiglare property” was evaluated. The results are shown in Table 4.

As shown in Table 4, the protective films for polarizing plates with a low refractive index layer obtained in Examples 13 to 18 are further excellent in antireflection performance.
Therefore, the protective film for polarizing plates with a low refractive index layer of the present invention obtained in Examples 7 to 18 The protective film for polarizing plates with a hard coat layer and the protective film for polarizing plates with a low refractive index layer of the present invention are liquid crystals. It has a preferable performance for use on the outside (viewing side) of the display device.

(Examples 16 to 20)
<Production of polarizer>
A 120 μm-thick polyvinyl alcohol film was immersed in an aqueous solution containing 1 part by mass of iodine, 2 parts by mass of potassium iodide, and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer (polarizing film). .

<< Saponification treatment >>
A protective film for polarizing plates of Examples 1 to 6, a triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd.) having a thickness of 80 μm, and a WV film (Fuji Fuji) coated with an optically anisotropic layer Film Co., Ltd.) was immersed in an aqueous 1.5 mol / L sodium hydroxide solution at 55 ° C. for 120 seconds, washed with water and dried.

<Preparation of polarizing plate>
The polarizer is formed on the surface on which the coating layer of the protective film for polarizing plates of Examples 1 to 6 subjected to the saponification treatment is not applied, and on the surface on which the optically anisotropic layer of the saponification treatment is not applied. Were bonded together using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive to produce polarizing plates of Examples 119 to 24.

(Comparative Example 11)
<Preparation of polarizing plate>
The polarizing plate of Comparative Example 11 was the same as the polarizing plate 19 except that the saponified 80 μm thick triacetyl cellulose film was used instead of the saponified polarizing plate protective film of Examples 1 to 5. Was made.

<< degree of polarization >>
The polarizing plates of Examples 19 to 24 and Comparative Example 11 obtained as described above were allowed to stand for 1,000 hours in an environment of 60 ° C. and 95% RH, and then the degree of polarization was measured. Based on the evaluation. In addition, the polarization degree was calculated | required from following Numerical formula (5) in wavelength 550nm.

[Evaluation criteria]
○: No problem with polarization degree of 99% or more.
Δ: The degree of polarization is 98% or more and less than 99%.
X: The degree of polarization is less than 98%.

<< Evaluation of coloring >>
The polarizing plate protective films of the polarizing plates of Examples 19 to 24 and Comparative Example 11 obtained as described above were visually observed, and the degree of coloring (yellowing) was determined based on the following evaluation criteria.

[Evaluation criteria]
○: Level with almost no coloring.
Δ: Level that is very thin but has no practical problem ×: Level of coloring is a problem.

<< Durability Evaluation >>
The polarization degree after treating the polarizing plates of Examples 19 to 24 and Comparative Example 11 obtained as described above for 500 hours at 60 ° C. and 90% RH was evaluated. The evaluation criteria were the same as the degree of polarization.

Table 5 shows the evaluation results of the polarizing plates of Examples 19 to 24 and Comparative Example 11.

  As shown in Table 5, it was recognized that the polarizing plates of Examples 19 to 24 had higher durability than the polarizing plate of Comparative Example 11.

(Examples 25-30)
<Production of liquid crystal display device>
The polarizing plate provided in the liquid crystal display device (MRT-191S, manufactured by Mitsubishi Electric Corp.) using a TN type liquid crystal cell is peeled off, and the polarizing plate of Examples 19 to 24 and Comparative Example 11 is replaced with the coating layer outside ( The liquid crystal display devices of Examples 25 to 30 and Comparative Example 12 were manufactured by sticking them through an adhesive so that the transmission axis of the polarizing plate coincides with the polarizing plate attached to the product. did.

<Evaluation of liquid crystal display device>
<< Light leakage evaluation after high and low humidity treatment (peripheral unevenness evaluation) >>
After the liquid crystal display device was treated at 60 ° C. and 90% for 24 hours and left in an environment of 25 ° C. and 60% for 2 hours, the liquid crystal display devices of Examples 25 to 30 and Comparative Example 12 were displayed in black in a dark room, from the front. Was evaluated by visual observation by a plurality of observers based on the following evaluation criteria. The evaluation results are shown in Table 6.

[Evaluation criteria]
A: No light leakage was observed. Δ: There was a light leakage, but there was no problem. X: Light leakage was clearly observed.

  As shown in Table 6, the liquid crystal display devices of Examples 25 to 30 exhibited better characteristics that the peripheral unevenness did not occur than the liquid crystal display device of Comparative Example 11.

  When the polarizing plate protective film of Examples 7-12 was used instead of the polarizing plate protective film of Examples 1-6 at the time of producing the polarizing plate of Examples 19-24, the polarizing plate performance, the periphery of the liquid crystal display device The surface hardness and anti-glare properties can be imparted without impairing the unevenness prevention performance, and when used on the outside of the liquid crystal display device, it is hard to get scratched, and the reflected image on the surface is reduced. Indicated.

  When the polarizing plate protective film of Examples 13-18 was used instead of the polarizing plate protective film of Examples 1-6 at the time of producing the polarizing plate of Examples 19-24, the polarizing plate performance, the periphery of the liquid crystal display device Without impairing unevenness prevention performance, surface hardness, antiglare, antireflection performance can be imparted, and when used on the outside of a liquid crystal display device, it is hard to be damaged, and reflection of reflected image on the surface is further reduced. Especially excellent performance was shown.

  Moreover, using the protective film for polarizing plates of the present invention, polarizing plates for IPS, VA, and OCB were prepared and used for each liquid crystal display device, and the light leakage was improved without deteriorating the display performance. I was able to.

FIG. 1A is a cross-sectional view showing a configuration in one embodiment of a polarizing plate protective film of the present invention. FIG. 1B is a cross-sectional view showing a configuration in one embodiment of the protective film for polarizing plate of the present invention. FIG. 1C is a cross-sectional view illustrating a configuration in one embodiment of the polarizing plate protective film of the present invention. FIG. 2A is a cross-sectional view showing a configuration in one embodiment of the polarizing plate of the present invention. FIG. 2B is a cross-sectional view illustrating a configuration in one embodiment of the polarizing plate of the present invention. FIG. 2C is a cross-sectional view showing a configuration in one embodiment of the polarizing plate of the present invention. FIG. 2D is a cross-sectional view showing a configuration in one embodiment of the polarizing plate of the present invention. FIG. 3A is a cross-sectional view showing a configuration in an embodiment of the liquid crystal display device of the present invention. FIG. 3B is a cross-sectional view showing a configuration in an embodiment of the liquid crystal display device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Protective film for polarizing plates 2 Transparent base film 3 Cover layer 4 Hard coat layer 5 Polarizing plate 6 Polarizer 7 Protective film for polarizing plates 8 Liquid crystal display device 9 Liquid crystal cell

Claims (19)

A coating composition for a coating layer containing at least an organic solvent is applied on a transparent substrate that swells or dissolves with the organic solvent, and then the organic solvent is dried to provide a low moisture-permeable coating on the transparent substrate. A protective film for a polarizing plate produced by a method for manufacturing a protective film for a polarizing plate comprising at least a drying step for forming a layer, wherein the residual amount of the organic solvent is 1.0 g / m ² or less. Protective film for polarizing plate. The protective film for polarizing plates according to claim 1, wherein the moisture permeability at 60 ° C. and 95% relative humidity is 700 g / m ² · day or less.   The protective film for polarizing plates according to any one of claims 1 to 2, wherein the transparent substrate comprises cellulose acylates.   The protective film for a polarizing plate according to claim 3, wherein the cellulose acylates are at least one of cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate.   The protective film for polarizing plates according to any one of claims 1 to 4, wherein the film thickness of the transparent substrate is from 30 µm to 120 µm.   The protective film for a polarizing plate according to claim 1, wherein the coating layer has a thickness of 0.2 μm to 10 μm.   The protective film for polarizing plates in any one of Claim 1 to 6 in which the coating composition for coating layers contains a polymer resin.   The protective film for polarizing plates according to claim 7, wherein the polymer resin contains any one of a resin containing a repeating unit derived from a chlorine-containing vinyl monomer, a fluorine resin, and an olefin resin.   The protective film for polarizing plates according to any one of claims 1 to 8, wherein a second layer that is at least one of a layer having a hard coat property and a layer having an antireflection layer is formed on the coating layer.   The protective film for polarizing plates according to any one of claims 1 to 9, wherein the coating composition for coating layer has at least one of a light stabilizer and a heat stabilizer. A coating step of coating a coating composition for a coating layer containing at least an organic solvent on a transparent substrate that is swollen or dissolved by the organic solvent;
A drying step of drying the organic solvent so that a residual amount of the organic solvent is 1.0 g / m ² or less to form a low moisture-permeable coating layer on the transparent substrate. The manufacturing method of the protective film for polarizing plates to perform.   The manufacturing method of the protective film for polarizing plates of Claim 11 in which the organic solvent component whose boiling point is 100 degrees C or less is contained 30 mass% or more of an organic solvent.   The organic solvent is composed of at least two kinds of organic solvent components, cannot swell or dissolve the transparent substrate, and the organic solvent component having a boiling point of 100 ° C. to 200 ° C. is 5% by mass or more of the organic solvent, 70 The manufacturing method of the protective film for polarizing plates in any one of Claim 11 to 12 contained less than mass%.   The drying step includes a first drying step of evaporating 50% or more of the organic solvent within 1 to 50 seconds after the coating layer coating composition is applied on the transparent substrate. The manufacturing method of the protective film for polarizing plates in any one of.   The drying step includes a first drying step of drying at a drying temperature of less than 70 ° C. until 50% or more of the organic solvent evaporates, and then a second drying step of drying at a drying temperature of 70 ° C. or more and less than 150 ° C. The manufacturing method of the protective film for polarizing plates of Claim 14 containing these.   16. The method according to claim 11, further comprising a second layer forming step of forming the second layer by drying the solvent after applying the coating composition for the second layer containing at least an organic solvent on the coating layer. The manufacturing method of the protective film for polarizing plates of crab.   A protective film for a polarizing plate produced by the method for producing a protective film according to claim 11.   A polarizing plate comprising: a polarizing film; and the protective film for polarizing plate according to claim 1 provided on at least one surface of the polarizing film.   An image display device comprising the polarizing plate protective film according to claim 1 or the polarizing plate according to claim 18.