JP2009237398A - Method for manufacturing polarizing plate - Google Patents

Abstract

A method of manufacturing a polarizing plate having a high degree of polarization and high transmittance and small transmission unevenness during black display in a liquid crystal display device is provided.
A polarizer and a support member made of an inorganic transparent material are bonded directly or indirectly with an adhesive layer made of a pressure-sensitive adhesive, and then irradiated with light containing a component absorbed by the polarizer. The polarizer is heated. Here, as a light irradiation amount irradiated to a polarizer, the range of 0.5-6W is preferable. The exothermic temperature of the polarizer is preferably in the range of 40 ° C to 90 ° C.
[Selection figure] None

Description

  The present invention relates to a method of manufacturing a polarizing plate suitable for a projection type liquid crystal display device such as a front projector and a rear projector.

  Polarizing plates are used in projection-type liquid crystal display devices such as front projectors and rear projectors. If the light transmitted through the polarizing plate is non-uniform, uneven transmission occurs. When black is displayed on a liquid crystal display device having a polarizing plate having such uneven transmission, black is displayed lightly in the portion where the uneven transmission occurs. In addition, it is known that the visibility is remarkably lowered when a display other than the black display is performed.

As a countermeasure for reducing transmission unevenness, it has been proposed to provide an optical element for correcting color unevenness in an RGB optical path in an optical system of a projection type liquid crystal display device. For example, Patent Document 1 proposes that a light shielding filter in which a light shielding pattern having a halftone dot pattern is formed in the middle of an optical path leading to liquid crystal panels of RGB colors. Patent Document 2 proposes that a light shielding means is provided in the relay optical system in an optical path of at least one of RGB.
Japanese Patent Laid-Open No. 6-265928 JP 2004-226814 A

  Under such circumstances, there has been a demand for a manufacturing method for obtaining a polarizing plate with reduced transmission unevenness.

As a result of intensive studies, the present inventors have reached the inventions described in [1] to [6] below.
[1] A method for producing a polarizing plate comprising a polarizer, a support member made of an inorganic transparent material, and an adhesive layer made of a pressure-sensitive adhesive located between the polarizer and the support member. ,
Bonding the polarizer and the support member directly or indirectly with the adhesive layer;
A method for producing a polarizing plate, comprising the step of irradiating the polarizer precursor obtained in the step with light containing a component absorbed by the polarizer to generate heat.
[2] The manufacturing method according to [1], wherein the light irradiation amount is in a range of 0.5 W to 6 W.
[3] The production method according to [1] or [2], wherein an exothermic temperature of the polarizer is in a range of 40 ° C to 90 ° C.
[4] The manufacturing method according to any one of [1] to [3], wherein the support member has a thermal conductivity of 5 W / mK or more.
[5] A polarizing plate produced by the production method described in any one of [1] to [4].
[6] A projection type liquid crystal display device comprising the polarizing plate according to [5].

  According to the present invention, a polarizing plate with reduced transmission unevenness can be obtained.

  A major feature of the production method according to the present invention is that the polarizer and the support member made of an inorganic transparent material are directly or indirectly bonded with an adhesive layer made of a pressure-sensitive adhesive, and then absorbed by the polarizer. In other words, the polarizer is heated by irradiating it with light.

  The light applied to the polarizer needs to include a component that is absorbed by the polarizer, and may be determined as appropriate based on the type of the polarizer. Examples of the light source include a high pressure mercury lamp, a metal halide lamp, a high pressure sodium lamp, a halogen lamp, and a xenon lamp. However, since light in the ultraviolet region of 400 nm or less and the infrared region of 700 nm or more may adversely affect the polarizer, it is preferable to cut from the irradiation light. Therefore, the wavelength range of the irradiation light is desirably in the range of 400 nm to 700 nm.

  As irradiation amount to a polarizer, the range of 0.5-6W is preferable. If the irradiation light quantity is less than 0.5 W, the transmission unevenness of the polarizer may not be suppressed. Conversely, if the light irradiation quantity is more than 6 W, the polarizer may be thermally deteriorated. A more preferable light irradiation amount is in the range of 2 to 4W. Moreover, the light irradiation time should just be 5 second or more, More preferably, it is the range of 0.5 hr-2 hr.

  The exothermic temperature of the polarizer is preferably in the range of 40 ° C. to 90 ° C., and in the range of preventing the polarizer from being deteriorated, the range of 50 ° C. to 80 ° C. is preferable. The exothermic temperature may be controlled by controlling the amount of light applied to the polarizer.

  The adhesive layer of the present invention is formed from a pressure sensitive adhesive. Here, the pressure-sensitive adhesive refers to an adhesive that does not use water, a solvent, heat, or the like, and is applied by applying a slight pressure at a normal temperature for a short time. Conventionally known pressure-sensitive adhesives can be used as such pressure-sensitive adhesives. For example, acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyethylene-based self-adhesive resins, and the like are preferably used.

  The polarizer and the support member may be directly bonded by an adhesive layer or indirectly bonded. When the polarizer and the support member are directly bonded by the adhesive layer, the adhesive layer may be formed on one or both of the polarizer and the support member, and either one from the viewpoint of productivity and workability. It is preferable to form it. As a method for forming the adhesive layer, a conventionally known method can be used. Examples include knife coating, screen printing, roll coating, and spin coating.

  As a form in the case of indirectly bonding the polarizer and the support member with an adhesive layer, for example, as shown in the examples described later, a transparent protective film is bonded to one side or both sides of the polarizer, and this protection is performed. The form which joins a film and a supporting member with an adhesive layer is mentioned. Of course, you may join a polarizer and a supporting member with an adhesive layer through another member other than a protective film.

  In the case where the support member is bonded to both sides of the polarizer, it suffices that at least one of the adhesive layers formed on both sides of the polarizer is made of a pressure-sensitive adhesive. Specifically, the adhesive layer on one side of the polarizer is made of a pressure-sensitive adhesive, and the adhesive layer on the other side of the polarizer is bonded to a conventionally known adhesive such as a curable adhesive or a liquid adhesive. It is preferable to consist of an agent. Examples of the curable adhesive include an ultraviolet curable adhesive and a thermosetting adhesive. More specifically, epoxy adhesives, silicone adhesives, acrylic adhesives, and the like can be given. Among these, solventless adhesives are particularly preferable because they are less foamed in vacuum. Examples of the solution adhesive include an adhesive having polyvinyl alcohol as an active ingredient, an adhesive having an acrylic resin as an active ingredient, and an adhesive having a urethane resin as an active ingredient. Industrially, an ultraviolet curable adhesive is most preferable because it easily controls the timing of curing.

  The polarizer used in the present invention is usually produced as follows. A film-like substrate made of a polyvinyl alcohol resin or the like is uniaxially stretched, and then dyed and adsorbed with a dichroic dye such as iodine or a dichroic dye. Next, the substrate on which the dichroic dye is adsorbed is treated with an aqueous boric acid solution, and then washed with water to obtain a polarizer. Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or may be performed after dyeing with a dichroic dye. When uniaxial stretching is performed after dyeing with a dichroic dye, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching in these plural stages. For uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched or uniaxially stretched using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 4 to 8 times.

  Examples of the base material of the polarizer include polyvinyl alcohol resins, polyvinyl acetate resins, ethylene / vinyl acetate (EVA) resins, polyamide resins, and polyester resins. Here, the polyvinyl alcohol-based resin includes polyvinyl alcohol which is a partially saponified product of polyvinyl acetate; vinyl acetate such as saponified EVA resin and other copolymerizable monomers (for example, ethylene or propylene Olefins, saponified products of copolymers with unsaturated carboxylic acids such as crotonic acid, acrylic acid, methacrylic acid, maleic acid, unsaturated sulfonic acids, vinyl ethers, etc .; polyvinyl alcohol modified with aldehyde Formal, polyvinyl acetal and the like are included. Among these, a film of a polyvinyl alcohol-based resin, particularly a film made of polyvinyl alcohol, is preferably used from the viewpoints of dye adsorption and orientation.

  Examples of the dichroic dye used in the present invention include iodine or a dichroic dye. In order to dye a film-like substrate with a dichroic dye, the substrate may be immersed in an aqueous solution containing the dichroic dye. When iodine is used as the dichroic dye, a method of immersing and dyeing the substrate in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 10 parts by weight per 100 parts by weight of water. It is. The temperature of this aqueous solution is usually about 20 to 40 ° C., and the immersion time in this aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of dyeing a substrate by immersing it in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻³ to 1 × 10 ⁻² parts by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate. The temperature of this aqueous solution is usually about 20 to 80 ° C., and the immersion time in this aqueous solution is usually about 30 to 300 seconds.

  A dichroic dye is preferable as the dichroic dye to be adsorbed and oriented on the substrate of the polarizer. By using dyes having different wavelength dependencies, respective polarizers are produced for the blue channel, the green channel, and the red channel of the projection type liquid crystal display device.

  Examples of the dichroic dye include compounds described in “Development of dichroic dyes for liquid crystal display devices” (Sone et al., Sumitomo Chemical, 2002-II, pp. 23-30).

Specifically, in the form of the free acid, the formula (I)
(In the formula, Me represents a metal atom selected from a copper atom, a nickel atom, a zinc atom and an iron atom. A1 represents an optionally substituted phenyl group or an optionally substituted naphthyl group. B1 represents a substituted atom. The naphthyl group which may be made and the oxygen atom couple | bonded with Me and the azo group shown by -N = N- are couple | bonded with carbon in which the carbon on a benzene ring is mutually adjacent. R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a carboxyl group, a sulfoxy group, a sulfonamide group, a sulfonealkylamide group, an amino group, an acylamino group, a halogen atom or a nitro group. Group.)
The dichroic dye shown by these is mentioned.

Also, in the form of the free acid, the formula (II)
(In the formula, A3 and B3 each independently represent an optionally substituted phenyl group or an optionally substituted naphthyl group, R3 and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, A C 1-4 alkoxyl group, a carboxyl group, a sulfoxy group, a sulfonamide group, a sulfonalkylamide group, an amino group, a halogen atom or a nitro group, and m represents 0 or 1.
The dichroic dye shown by these is mentioned.

In the form of the free acid, the formula (III)
Q1-N = N-Q2-X-Q3-N = N-Q4 (III)
[Wherein, Q1 and Q4 each independently represent an optionally substituted phenyl group or an optionally substituted naphthyl group, and X represents a chemical formula (III-1)
Or chemical formula (III-2)
The bivalent residue shown by is shown. Q2 and Q3 each independently represent an optionally substituted phenylene group. ]
The dichroic dye shown by these is mentioned.

And the formula (IV)
[In the formula, Me represents a metal atom selected from a copper atom, a nickel atom, a zinc atom and an iron atom, Q5 and Q6 each independently represents a naphthyl group which may have a substituent, and is bonded to Me. In the oxygen atom and the azo group represented by -N = N-, the carbon on the benzene ring is bonded to the carbon adjacent to each other. Y is the formula (IV-1)
Or formula (IV-2)
The bivalent residue shown by is shown. R5 and R6 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms or a sulfoxy group. ]
The dichroic dye shown by these is mentioned.

  Further, as dichroic dyes, C-I Direct Yellow-12, C-I Direct Red 31, C-I Direct Red 28, C-I Direct Yellow 44 , C Eye Direct Yellow 28, C I Direct Orange 107, C I Direct Red 79, C I Direct Red 2, C I Direct Red 2 81, see eye direct orange 26, see eye direct orange 39, see eye direct red 247 and see eye direct yellow 142 Examples are those represented by an index generic name (Color Index Generic Name).

  The dichroic dye may be used in the form of a free acid, or may be used in the form of an amine salt such as an ammonium salt, an ethanolamine salt, or an alkylamine salt. Usually, a lithium salt, a sodium salt, Used in the form of alkali metal salts such as potassium salts. Such dichroic dyes may be used alone or in combination of two or more.

  Next, the boric acid treatment after dyeing with the dichroic dye is performed by immersing the dyed substrate in an aqueous boric acid solution. The boric acid content in the boric acid aqueous solution is usually about 1 to 15 parts by weight, preferably about 5 to 10 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the aqueous boric acid solution preferably contains potassium iodide. The content of potassium iodide in the boric acid aqueous solution is usually about 2 to 20 parts by weight, preferably 5 to 10 parts by weight per 100 parts by weight of water. The immersion time in the boric acid aqueous solution is usually about 100 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 ° C. or higher, preferably 50 to 80 ° C. Furthermore, if necessary, the fixing treatment may be performed with an aqueous solution containing a cationic polymer compound.

  The substrate after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated substrate in water. After washing with water, a drying process is performed to obtain a polarizer. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 2 to 120 seconds. The drying process performed thereafter is usually performed using a hot air dryer or a far infrared heater. The drying temperature is usually 40 to 100 ° C. The processing time in the drying process is usually about 120 to 600 seconds.

  The thickness of the polarizer is not particularly limited, but is generally preferably 100 μm or less, more preferably in the range of 10 to 50 μm, and still more preferably in the range of 25 to 35 μm for the purpose of reducing the thickness of the polarizing plate.

  In order to protect the polarizer, a protective film may be bonded to one side or both sides of the polarizer. As the transparent protective film to be bonded to the polarizer, a film made of a polymer having low birefringence and excellent in transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferable. Examples of such films include cellulose acetate resins such as TAC (triacetylcellulose), acrylic resins, fluorine resins such as tetrafluoroethylene / hexafluoropropylene copolymers, polycarbonate resins, and polyethylene. Polyester resin such as terephthalate, polyimide resin, polysulfone resin, polyethersulfone resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyolefin resin or polyamide resin, etc. are formed into a film. What was processed is mentioned. Among these, a triacetyl cellulose film or a norbornene-based thermoplastic resin film whose surface is saponified with an alkali or the like can be preferably used from the viewpoints of polarization characteristics and durability. The norbornene-based thermoplastic resin film is particularly suitable because the film is a good barrier from heat and wet heat, so the durability of the polarizing plate is greatly improved and the dimensional stability is greatly improved due to its low moisture absorption rate. Can be used. For forming into a film, a conventionally known method such as a casting method, a calendar method, or an extrusion method can be used.

  Although there is no limitation in the thickness of a protective film, from a viewpoint of thickness reduction of a polarizing plate, 500 micrometers or less are usually preferable, More preferably, it is the range of 5-300 micrometers, More preferably, it is the range of 5-150 micrometers.

  The support member used in the present invention is made of an inorganic transparent material. Examples of the inorganic transparent material include silicate glass, borosilicate glass, titanium silicate glass, fused quartz (quartz glass), crystal, sapphire, YAG crystal, fluorite, magnesia, spinel (MgO.Al2O3), and the like. Is done. Among these, those having a thermal conductivity of 5 W / mK or more are preferable. Examples of such a material include quartz glass, sapphire, magnesia, and spinel. By using a material with high thermal conductivity, the heat generated in the polarizer can be efficiently radiated to the outside when used in a projection type liquid crystal display device, etc., and the temperature distribution in the plane of the polarizer and the support member is It becomes uniform and transmission unevenness derived from a change in phase difference due to thermal deformation can be reduced.

  The thickness of the support member is preferably in the range of 0.05 mm to 3 mm, more preferably in the range of 0.08 to 2 mm from the viewpoint of yield in the case of industrialization and size matching with the projector optical system to be applied. It is. When the thickness is 0.05 mm or more, breakage of the glass as a supporting member during processing is suppressed, and stable production can be achieved. Moreover, the polarizing plate obtained can be reduced in size and weight as it is the thickness of 3 mm or less.

  It is desirable to apply an antireflection treatment according to the wavelength of light to be used on the outer surface of the support member that contacts the air. Examples of the antireflection treatment include a method by forming a dielectric multilayer film by a sputtering method or a vacuum deposition method, and a method by applying one or more low refractive index layers by coating. Further, the antireflection surface may be provided with an antifouling treatment for preventing dirt from adhering to the surface. Examples of the antifouling treatment include forming on the surface a thin film layer containing fluorine that hardly affects the antireflection performance.

  The polarizer and the polarizing plate obtained by the manufacturing method described above are suitably used for, for example, a projection type liquid crystal display device (projector). The details will be described by taking the optical system of the rear projector shown in FIG. 1 as an example.

  The light bundle using the high-pressure mercury lamp 111 as a light source is first made uniform and polarized in the cross-section of the anti-beam bundle by the first lens array 112, the second lens array 113, the polarization conversion element 114, and the superimposing lens 115. Is called. Specifically, the light bundle emitted from the light source 111 is divided into a number of minute light bundles by the first lens array 112 in which minute lenses 112a are arranged in a matrix. The second lens array 113 and the superimposing lens 115 are provided such that each of the divided light bundles irradiates the entire three LCD panels 140R, 140G, and 140B that are the illumination target. The entire surface of the LCD panel incident side has substantially uniform illuminance.

  The polarization conversion element 114 is usually configured by a polarization beam splitter array, and is disposed between the second lens array 113 and the superimposing lens 115. As a result, random polarized light from the light source is converted into polarized light having a specific polarization direction in advance, thereby reducing the light loss at the incident-side polarizing plate described later, thereby improving the screen brightness.

  The light with uniform brightness and polarized light is sequentially separated into red channel, green channel, and blue channel by the dichroic mirrors 121, 123, 132 for separating the three primary colors of RGB through the reflection mirror 122, respectively. The light enters the LCD panels 140R, 140G, and 140B.

  Regarding the LCD panels 140R, 140G, and 140B, the polarizing plate (incident side) 142 and the polarizing plate (exit side) 143 of the present invention are arranged on the incident side and the outgoing side, respectively.

  A description will be given of two polarizing plates arranged on the incident side and the emission side with a liquid crystal panel sandwiched between the RGB optical paths. The polarizing plate (incident side) 142 and the polarizing plate (exit side) 143 arranged in each optical path are arranged in a configuration in which the absorption axis is orthogonal, and each LCD panel 140R, 140G, 140B arranged in each optical path. It fulfills the function of converting the polarization state controlled for each pixel by the image signal into light quantity.

  The polarizing plate of the present invention has a configuration common to all the optical paths of the blue channel, the green channel, and the red channel, and is effective as a polarizing plate having excellent durability in any optical path. It is particularly effective.

  An optical image created by transmitting incident light with different transmittance for each pixel according to the image data of the LCD panels 140R, 140G, and 140B is synthesized by the cross dichroic prism 150, and is projected by the projection lens 170 to the screen 180. Is enlarged and projected.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples at all.

Example 1
A polyvinyl alcohol film (“VF-PX” manufactured by Kuraray Co., Ltd., hereinafter referred to as “PVA film”) is uniaxially stretched, dyed with a polyazo dye that absorbs green color, dried, and the degree of polarization at a thickness of 28 μm and 550 nm. A polarizer for a projector green channel having a transmittance of 99.9% and a transmittance of 43.0% was obtained. An 80 μm thick triacetyl cellulose film (TAC film KC8UY, manufactured by Konica Minolta, Inc., hereinafter referred to as “KC8UY”) is an adhesive in which a water-soluble polyamide epoxy resin is added to a carboxyl group-modified polyvinyl alcohol resin on both sides of this polarizer. In some cases, a polarizing plate precursor was prepared. A pressure-sensitive adhesive is applied to one surface of the obtained polarizing plate precursor to form an adhesive layer, and a blue plate glass substrate having a thickness of 0.5 mm is further bonded through this adhesive layer. The polarizing plate laminated | stacked in order of the plate glass substrate / protective film / polarizer / protective film was obtained.

  This polarizing plate was installed in a projection type liquid crystal display device (projector) (PLV-80, manufactured by Sanyo Electric Co., Ltd.) as a green channel output polarizing plate. This projection type liquid crystal display device is placed in a dark room, and using a color illuminometer (CL-200, manufactured by Konica Minolta Co., Ltd.), tristimulus values XYZ at 13 points in the projection plane are measured by the following method and converted into x and y. The in-plane color distribution obtained after this was defined as Δxo and Δyo. “Transmission unevenness during black display” refers to the color distribution on the projection screen when the projection type liquid crystal display device displays black.

  This polarizing plate was heated by irradiating 2.5 W light. In just a few seconds from the start of light irradiation, the temperature of the polarizing plate reached about 60 ° C., and the polarizing plate was heated for 1 hour at this temperature in which the amount of heating and the amount of heat released were balanced. After that, it was installed again in the above-mentioned projection type liquid crystal display device, and measurement and calculation were performed in the same manner, and the obtained in-plane color distribution was set to Δx, Δy. The results are shown in Table 1. As apparent from Table 1, Δx <Δxo and Δy <Δyo resulted, and the in-plane color distribution was reduced by the heat treatment by light irradiation, that is, transmission unevenness was reduced.

(Measurement of transmission unevenness)
In order to prevent the influence of ambient light, the evaluation was performed in a dark room. As shown in FIG. 2, let the four vertices of the projection screen by a projection-type liquid crystal display device be coordinate points (0,0), (100,0), (100,100), and (0,100), respectively. In addition to these four vertices, nine coordinate points “(25,25), (50,25), (75,25), (25,50), (50,50), (75,50), (25,75), (50,75), (75,75) "are selected as measurement points, and tristimulus values XYZ are measured using a color illuminometer at the coordinate points of the total 13.
Then, x and y are calculated from the following equations.
x = X / (X + Y + Z)
y = Y / (X + Y + Z)
Next, let Δx be the difference between the maximum value and the minimum value in x of the 13 coordinate points, and similarly let Δy be the difference between the maximum value and the minimum value of y. Transmission unevenness is evaluated by the values of Δx and Δy. As the values of Δx and Δy are smaller, the transmission unevenness is smaller.

(Example 2)
A pressure sensitive adhesive was applied to one surface of the polarizing plate precursor obtained in the same manner as in Example 1 to form an adhesive layer, and a quartz substrate having a thickness of 0.5 mm was pasted through this adhesive layer. The polarizing plate laminated | stacked in order of the quartz substrate / protective film / polarizer / protective film was obtained. In addition, in order to avoid the phase difference influence of a quartz substrate when bonding, it performed by making the absorption axis of a polarizer match with the slow axis of a quartz substrate. Using this polarizing plate, the initial in-plane color distribution was set to Δxo and Δyo in the same manner as in Example 1.

  The polarizing plate was heated by irradiating with 2.0 W light. In just a few seconds from the start of light irradiation, the temperature of the polarizing plate reached about 50 ° C., and the polarizing plate was heated for 1 hour at this temperature in which the amount of heating and the amount of heat released were balanced. After that, it was installed again in the above-mentioned projection type liquid crystal display device, and measurement and calculation were performed in the same manner, and the obtained in-plane color distribution was set as Δx and Δy. The results are shown in Table 1. As is apparent from Table 1, as a result, Δx <Δxo and Δy <Δyo were obtained, and the in-plane color distribution was reduced by the heat treatment by light irradiation, that is, the transmission unevenness was reduced.

(Example 3)
A triacetyl cellulose film (TAC film KC4UY, manufactured by Konica Minolta Co., Ltd.) having a film thickness of 40 μm with an adhesive obtained by adding a water-soluble polyamide epoxy resin to a carboxyl group-modified polyvinyl alcohol resin on one side of a polarizer obtained in the same manner as in Example 1. Hereinafter, it may be referred to as “KC4UY”), and a polarizing plate precursor was prepared. A pressure-sensitive adhesive is applied to the surface of the polarizer of the obtained polarizing plate precursor to form an adhesive layer, and a blue plate glass substrate having a thickness of 0.5 mm is bonded through the adhesive layer. The polarizing plate which laminated | stacked in order of the board | substrate / polarizer / protective film was obtained. Using this polarizing plate, the initial in-plane color distribution was set to Δxo and Δyo in the same manner as in Example 1.

  This polarizing plate was heated by irradiating 3.5 W of light. In just a few seconds from the start of light irradiation, the temperature of the polarizing plate reached about 70 ° C., and the polarizing plate was heated for 1 hour at this temperature in which the amount of heating and the amount of heat released were balanced. After that, it was installed again in the above-mentioned projection type liquid crystal display device, and measurement and calculation were performed in the same manner, and the obtained in-plane color distribution was set as Δx and Δy. The results are shown in Table 1. As is apparent from Table 1, as a result, Δx <Δxo and Δy <Δyo were obtained, and the in-plane color distribution was reduced by the heat treatment by light irradiation, that is, the transmission unevenness was reduced.

The case where Δx and Δy become smaller than Δxo and Δyo due to light irradiation is determined as “good”.

  According to the present invention, a polarizing plate with reduced transmission unevenness can be obtained.

It is a figure explaining the one aspect | mode of a projection type liquid crystal display device. It is explanatory drawing of the location which measures the color distribution in the projection screen of a projection type liquid crystal display device.

Explanation of symbols

111: High pressure mercury lamp 112: First lens array 113: Second lens array 114: Polarization conversion element 115: Superimposing lens 121: Red channel dichroic mirror 122: Reflection mirror 123: Green channel dichroic mirror 132: Blue channel reflection mirror 134: Blue channel reflection mirror 135: Condenser lens 136: Red channel reflection mirror 140B: Blue channel liquid crystal panel 140G: Green channel liquid crystal panel 140R: Red channel liquid crystal panel 142: Polarizing plate 143: Polarizing plate 150: Cross dichroic prism 170: Projection lens 180 :screen

Claims (6)

A polarizing plate comprising a polarizer, a support member made of an inorganic transparent material, and an adhesive layer made of a pressure-sensitive adhesive located between the polarizer and the support member,
Bonding the polarizer and the support member directly or indirectly with the adhesive layer;
A method for producing a polarizing plate, comprising the step of irradiating the polarizing plate precursor obtained in the step with light containing a component absorbed by the polarizer to generate heat.   The manufacturing method according to claim 1, wherein the light irradiation amount is in a range of 0.5 to 6 W.   The manufacturing method according to claim 1 or 2, wherein the exothermic temperature of the polarizer is in the range of 40C to 90C.   The manufacturing method according to claim 1, wherein the support member has a thermal conductivity of 5 W / mK or more.   The polarizing plate manufactured by the manufacturing method as described in any one of Claims 1-4.   A projection-type liquid crystal display device comprising the polarizing plate according to claim 5.