JPH1068818A - Optical laminate and liquid crystal display device using the same - Google Patents

Abstract

(57) [Problem] To provide an optical laminate excellent in use environment resistance, which can improve the visibility of a liquid crystal display element, in particular, can suppress a decrease in the visibility due to a change in use environment. An optical laminate (7) having a pressure-sensitive adhesive layer (5) formed on the protective film (3) side of a polarizing plate (4) obtained by attaching a protective film (3) to at least one surface of a polarizing film (1) via an adhesive layer (2). It is. Then, using two optical laminates 7,
The polarizing plate 4 of the optical laminate 7 is adhered to both sides of the glass plate so that the optical axes of the polarizing plates 4 are orthogonal to each other. When the following (X) is measured, the measured value satisfies the following characteristic (Y). is there. (X) A laminate obtained by laminating the above-mentioned polarizing plate 4 on both surfaces of a glass plate was left in an atmosphere at 69 ° C. for 750 hours, and then the color coordinates in the vertical direction were measured at nine points in the in-plane uniform division. x and y values. (Y) Each of the minimum values of the x value and the y value is 0.2
And the difference between the maximum and minimum x values and y
The difference between the maximum value and the minimum value is 0.1 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the visibility of a liquid crystal display element used in a liquid crystal display device such as an instrument of a car or a machine, and more particularly, to a suppression of a decrease in the visibility with a change in a use environment. And a liquid crystal display device using the same.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used in desktop electronic calculators, electronic timepieces, word processors, instruments for automobiles and machinery, and the demand for polarizing plates has been increasing accordingly. Generally, a polarizing plate is obtained by forming a protective film on both sides or one side of a polarizing film having polarizing ability via an adhesive layer. Currently known representative polyvinyl alcohol (hereinafter abbreviated as “PVA”) polarizing films include those obtained by dyeing a PVA film with iodine and those obtained by dyeing a dichroic dye. These are prepared by forming an aqueous solution of PVA into a film and uniaxially stretching it and dyeing it with iodine, or dyeing it with iodine and then stretching it uniaxially, and preferably performing a durability treatment with a boron compound. As the above protective film, a cellulose acetate film is widely used because it has excellent optical transparency and non-orientation as a surface protective film.

[0003]

However, in the above-mentioned liquid crystal display device using the conventional polarizing plate, the liquid crystal (liquid crystal display element), the alignment film,
Since an organic material is widely used for a polarizing plate or the like, there is a problem that a display characteristic of a liquid crystal display element is greatly reduced due to a change in a use environment of the liquid crystal display device.

[0004] The present invention has been made in view of such circumstances, and has improved the visibility of a liquid crystal display element, and in particular, has excellent use environment resistance that can suppress a decrease in visibility with respect to a change in use environment. It is an object of the present invention to provide an optical laminate and a liquid crystal display device using the same.

[0005]

Means for Solving the Problems In order to achieve the above object, the present invention relates to a polarizing plate having a protective film adhered to at least one side of the polarizing film via an adhesive layer. An optical laminate on which an adhesive layer is formed, using two optical laminates, on both sides of a glass plate,
When the optical laminates are adhered so that the optical axes of the polarizing plates of the optical laminate are orthogonal to each other and the following (X) is measured, the optical laminate having the measured value satisfying the following property (Y) is defined as a first gist. . (X) The laminate obtained by adhering the above-mentioned polarizing plate to both surfaces of a glass plate was left in an atmosphere at 69 ° C. for 750 hours, and the color coordinate in the vertical direction was measured at nine points in the in-plane uniform division. Value and y value. (Y) Each of the minimum values of the x value and the y value is 0.2
And the difference between the maximum and minimum x values and y
The difference between the maximum value and the minimum value is 0.1 or less.

A second aspect of the present invention is a liquid crystal display device in which the optical laminate is adhered to at least one surface of a liquid crystal cell via the adhesive layer.

The inventor has conducted intensive studies on improving the visibility of the liquid crystal display element against changes in the use environment, that is, on improving the use environment resistance. As a result, attention was paid to the vertical color coordinates of the laminate obtained by using the two optical laminates and attaching them to both surfaces of the glass plate so that the optical axes of the polarizing plates of the optical laminate were orthogonal to each other. It has been found that the color coordinates in the vertical direction are closely related to the use environment resistance. As a result of further research, the above laminate was
After standing in an atmosphere of 9 ° C. for 750 hours, when the vertical color coordinates are measured at nine points in the plane, each of the minimum values of the x value and the y value is 0.2 or more, and , X
If the difference between the maximum value and the minimum value of the value and the difference between the maximum value and the minimum value of the y value are all 0.1 or less, the visibility of the liquid crystal display element against a change in the use environment can be improved, and The present inventors have found that the use environment is improved and arrived at the present invention.

In the present invention, the x- and y-values obtained by measuring the color coordinates in the vertical direction at 9 points in the plane after leaving the laminate in an atmosphere of 69 ° C. for 750 hours are determined by Otsuka Electronics Co., Ltd. It can be measured using an optical measuring device RETS2000 manufactured by Toshiba Corporation. The color coordinates are based on the International Commission on Illumination (CIE) standards and JIS Z870.
According to 1.

[0009]

Next, embodiments of the present invention will be described in detail.

As shown in FIG. 1, for example, the optical laminate of the present invention has a protective film 3 laminated on one side of a polarizing film 1 with an adhesive layer 2 interposed therebetween. The pressure-sensitive adhesive layer 5 is laminated on the side. In the figure, reference numeral 7 denotes an optical laminate.

The polarizing film 1 is not particularly limited, and examples thereof include a PVA-based film, an ethylene vinyl alcohol-based film, a cellulose-based film, and a polycarbonate-based film.
A-based films are preferred.

The above PVA is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. However, the present invention is not limited to this, and a small amount of unsaturated carboxylic acid (salt, ester, amide) may be used. , Nitriles, etc.), olefins, vinyl ethers, unsaturated sulfonates, and the like, and may contain components that can be copolymerized with vinyl acetate. The average degree of saponification in PVA is 85-100.
Mole%, preferably 98-100 mol% is practical. Further, as the average polymerization degree of the PVA of the present invention, any one can be used, but 1500 to 5000, preferably 2600 to 5000, more preferably 3000 to 5
000 is advantageous.

The material for forming the adhesive layer 2 is not particularly limited. For example, PVA resins (including PVA modified with acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group, etc.) And an aqueous solution of a boron compound or the like is suitably employed, and among them, PVA
An aqueous solution of a base resin, particularly PVA, is preferred. About this PVA, the average degree of polymerization is 500 to 4000, preferably 1
PVA having a saponification degree of 90.0 to 99.9 mol%, preferably 95.0 to 99.9 mol%, is suitably used. Further, the concentration of the aqueous solution is 0.1 to 15
% By weight, especially 1 to 10% by weight, is preferred.

Examples of the material for forming the protective film 3 include a conventionally known cellulose acetate film,
Acrylic resin film, polyester resin film, polyolefin resin film, polycarbonate film, polyetheretherketone film,
Polysulfone-based films and the like can be mentioned.
Cellulose diacetate or cellulose triacetate film (TA
Cellulose acetate films such as C) are preferred.

The material for forming the pressure-sensitive adhesive layer 5 formed on the surface of the protective film 3 of the polarizing plate 4 is not particularly limited as long as it has transparency. Particularly, those mainly composed of a copolymer of an acrylate ester and an α-monoolefin carboxylic acid (including those to which vinyl monomers such as acrylonitrile, vinyl acetate, and styrene are added) It is preferable in that the polarizing characteristics of the polarizing film 1 are not hindered. As the acrylate, for example, butyl acrylate, ethyl acrylate,
Examples include methyl acrylate and 2-ethylhexyl acrylate. Examples of the α-monoolefin carboxylic acid include acrylic acid, maleic acid, itaconic acid, methacrylic acid, crotonic acid and the like.

The liquid crystal display device of the present invention is, for example, a liquid crystal display device in which the adhesive layer 5 of the optical laminate 7 is adhered to one surface of a liquid crystal cell 6 as shown in FIG. Alternatively, as shown in FIG. 3, a liquid crystal cell 6 in which the optical laminates 7 are adhered to both sides of the liquid crystal cell 6 with an adhesive layer 5 interposed therebetween, may be used. When the optical laminate 7 is attached to both sides of the liquid crystal cell 6, the optical axes of the polarizing plates 4 of the optical laminate 7 are set so as to be orthogonal to each other.

The liquid crystal cell 6 is not particularly limited, and may be a conventionally known one. For example,
Liquid crystal cells of TN type, STN type, TFT type, transmissive type, anti-transmissive type, reflective type and the like can be mentioned.

Next, the method for producing the optical laminate 7 and the liquid crystal display device of the present invention will be specifically described. First, a method for manufacturing the optical laminate 7 will be described.

The polarizing film 1 can be obtained, for example, by casting a stock solution obtained by dissolving PVA in a solvent, and then stretching, dyeing, and treating with a boron compound.

Examples of the solvent used in the preparation of the stock solution include water, dimethyl sulfoxide (DMSO), N-methylpyrrolidone, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and triethylene glycol. Solvents such as polyhydric alcohols such as methylolpropane and amines such as ethylenediamine and diethylenetriamine are used. These may be used alone or in combination of two or more. In the above solvent, for example,
A small amount of water of 5 to 30% by weight may be contained. The concentration of PVA in the stock solution is practically 5 to 20% by weight.

The method for forming a film of the above-mentioned stock solution is not particularly limited, and examples thereof include an arbitrary method such as a casting method and an extrusion method. Specifically, by a dry / wet film forming method, that is, the stock solution is temporarily discharged from the base slit into air or into an inert atmosphere such as nitrogen, helium, or argon,
Then, it is guided into a coagulation bath to obtain an unstretched film. In addition, the film forming stock solution discharged from the die may be partially dried on a roller, a belt conveyor, or the like, and then introduced into the coagulation bath. Further, a so-called gel film forming method of introducing a stock solution of PVA into a coagulation bath to form a film can also be performed.

The solvent used in the coagulation bath is P
There is no particular limitation as long as it has miscibility with the solvent of VA. For example, methanol, ethanol, propanol,
Alcohols such as butanol, acetone, benzene,
Examples include toluene.

Next, the PVA obtained as described above is used.
The unstretched film is stretched, dyed, and treated with a boron compound. In this case, stretching, dyeing, and boron compound treatment may be performed separately or simultaneously. For example, the PV
A Unstretched film is stretched and immersed in an aqueous solution of iodine or a dichroic dye for dyeing, or stretched and dyed simultaneously, or dyed with iodine or a dichroic dye and stretched, and then stretched. A method of treating a compound can be given. In addition, there is a method of stretching in a solution of a boron compound after dyeing, and the like can be appropriately selected and used.
In the present invention, it is preferable to perform stretching during at least one of the dyeing and boron compound treatment steps.

The stretching is preferably performed in a uniaxial direction by 3.5 to 10 times, preferably 4.5 to 7 times. At this time, slight stretching (extending to a degree that prevents shrinkage in the axial direction or more) may be performed in the direction perpendicular to the above direction. The temperature condition during stretching is preferably selected from 40 to 130 ° C. Further, the stretching ratio may be finally set in the above range, the stretching operation is not only one step,
What is necessary is just to carry out at the stage of the arbitrary range of a manufacturing process.

In the above stretching, the film thickness after stretching is
It is preferably performed to have a thickness of 20 μm or less, and particularly preferably 15 to 20 μm. In addition, as a raw film of PVA before stretching, the film thickness is 30 to 100 μm,
Preferably, 50 to 90 μm is required. That is, 3
If the thickness is less than 0 μm, the film cannot be stretched. On the other hand, if the thickness exceeds 100 μm, the accuracy of the film thickness decreases and becomes unsuitable.

The dyeing of the film with iodine is usually carried out by contacting an aqueous solution of iodine-potassium iodide. In this case, the concentration of iodine is 0.1 to 2 g.
/ L, the concentration of potassium iodide is 10 to 50 g / l, and the weight ratio of iodine to potassium iodide is suitably iodine / potassium iodide = 20 to 100. The staining time is 30
About 500 seconds is practical, and the temperature of the treatment bath is 5 to 5 seconds.
0 ° C. is preferred. In addition, a small amount of an organic solvent compatible with water may be contained in addition to the aqueous solution. As the contact means, any means such as immersion, coating, spraying and the like can be applied.

The dyed film is then treated with a boron compound. Boric acid and borax are practical as boron compounds. The boron compound is preferably used in the form of an aqueous solution or a mixed solution of water and an organic solvent at a concentration of 60 g / l or more, particularly preferably a concentration of 60 to 200 g.
/ L. That is, if the concentration is less than 60 g / l,
This is because the use environment resistance of the liquid crystal display element tends to be inferior. It is practically preferable that a small amount of potassium iodide coexist in the liquid. The concentration of potassium iodide is preferably at least 30 g / l, particularly preferably 30 to 70 g / l.
g / l. The treatment method is preferably an immersion method, but of course, a coating method and a spraying method can also be performed. Temperature during processing is 40
~ 70 ° C, the treatment time is preferably about 5-20 minutes,
Further, if necessary, a stretching operation may be performed during the treatment.

Then, the polarizing film is further subjected to a water washing treatment.

Next, the material for forming the adhesive layer 2 is applied onto one surface of the polarizing film or the surface of the protective film 3 obtained by the above treatment. In this case, the adhesive layer 2 forming material is advantageously applied so as to form a uniform film on the polarizing film 1 surface or the protective film 3 surface,
Upon application, the thickness after drying is 0.01 to 10 μm,
It is practical that the thickness is preferably 0.05 to 5 μm. That is, if it is less than 0.01 μm, the adhesive strength is insufficient, and if it exceeds 10 μm, the effect does not increase for the amount used, and the appearance deteriorates, which is not practical. The application operation is not necessarily limited to an application means using a roll or the like, and means such as a spraying method and an immersion method can be applied. Further, it is more effective if the surface of the protective film 3 is saponified with alkali, or subjected to plasma treatment, glow discharge treatment, corona discharge treatment, high frequency treatment, electron beam treatment, or the like.

Then, the material for forming the adhesive layer 2 is applied to at least one surface of the polarizing film 1 and the protective film 3 is bonded thereto.
By performing heat treatment at 5 to 90 ° C. for 1 to 20 minutes, preferably 1 to 15 minutes, a polarizing plate 4 in which one surface of the polarizing film and three surfaces of the protective film are firmly adhered to each other is obtained. Also,
The material for forming the adhesive layer 2 may be applied on the surface of the protective film 3 and bonded to the polarizing film 1 to form the polarizing plate 4.

Then, the material for forming the pressure-sensitive adhesive layer 5 is formed on the surface of the protective film 3 of the polarizing plate 4 by coating or the like, whereby the optical laminate 7 as shown in FIG. 1 is obtained.
In FIG. 1, only one side of the polarizing film 1 is provided.
The optical laminate 7 on which the adhesive layer 2, the protective film 3, and the pressure-sensitive adhesive layer 5 are formed is shown. The adhesive layer 2, the protective film 3, and the adhesive layer 2 are provided on both surfaces of the polarizing film 1 in the same manner as described above. It is also possible to form each of the agent layers 5.

The pressure-sensitive adhesive layer 5 preferably has a change in the gelation fraction in the range of 5 to 20%, particularly preferably 5 to 15%. That is, if the change value of the gelation fraction is out of the range of 5 to 20%, the use environment resistance of the liquid crystal display element tends to be inferior.

The change in the gelation fraction can be determined as follows. That is, the pressure-sensitive adhesive is collected from the pressure-sensitive adhesive layer 5 using tweezers, placed in a sample bottle (tare), weighed, and the weight of the sample bottle is subtracted therefrom to obtain the pressure-sensitive adhesive amount (). And put 40 ml of toluene in the sample bottle,
This is left at 23 ° C. for 48 hours. Thereafter, a 200 mesh basket (tare) [SUS200 mesh 5 × 5 cm]
Is measured, and the gel of the undissolved pressure-sensitive adhesive is filtered with the use of the gel. Subsequently, the gel is placed in a dryer at 105 ° C. for 2 hours to distill off the toluene. Finally, the weight after drying is measured, the weight () of the undissolved pressure-sensitive adhesive is measured, and the gelation fraction () is determined by the following equation (1).

[0034]

## EQU1 ## Gelation fraction (%) = (÷) × 100 (1)

Next, after heating the above-mentioned pressure-sensitive adhesive at 69 ° C. for 750 hours, the gelation fraction () is calculated by the above formula (1).
Ask for.

Then, from the gelation fraction () before the heat treatment and the gelation fraction () after the heat treatment, the change value of the gelation fraction is determined by the following equation (2).

[0037]

## EQU2 ## Change in gelation fraction (%) = ｛(−) /｝ × 100 (2)

In the optical laminate 7 of the present invention thus obtained, the thickness of the polarizing film 1 is not particularly limited, and the thickness of the adhesive layer 2 is preferably 0.01 to 10 μm, and particularly preferably. It is 0.05-5 μm. And
The thickness of the protective film 3 is preferably from 10 to 200 μm, particularly preferably from 30 to 150 μm. Also,
The thickness of the pressure-sensitive adhesive layer 5 is preferably 1 to 100 μm,
Particularly preferably, it is 5 to 50 μm.

Next, a method for manufacturing the liquid crystal display device of the present invention will be described. First, the liquid crystal display device shown in FIG. 2 will be described. This liquid crystal display device is obtained by adhering an optical laminate 7 to one surface of a liquid crystal cell 6 with the above-mentioned adhesive layer 5 interposed therebetween.

Next, the liquid crystal display device shown in FIG. 3 will be described. This liquid crystal display device is obtained by adhering the optical laminates 7 via the adhesive layer 5 to both surfaces of the liquid crystal cell 6 such that the optical axes of the polarizing plates 4 are orthogonal to each other.

In the liquid crystal display device of the present invention thus obtained, the thickness of the liquid crystal cell 6 is usually 0.5
About 5 mm.

As a specific example of a liquid crystal display device using the optical laminate 7 of the present invention, there is a color STN liquid crystal display module shown in FIG. In the figure, reference numeral 13 denotes a liquid crystal cell. The liquid crystal cell 13 has a configuration in which transparent electrodes 11 and 12 are adhered to both surfaces of a liquid crystal 10, respectively. The optical laminates 7 are adhered to both surfaces of the liquid crystal cell 13 via the glass substrates 14 and 15, respectively, such that the optical axes of the polarizing plates (one component of the optical laminate 7) are orthogonal to each other. ing. A color filter 16 is interposed between the glass substrate 14 and the transparent electrode 11 on the side opposite to the backlight, with the liquid crystal cell 13 as the center.

In the present invention, the optical laminate 7 is
When the following (X) is measured, it is necessary that the measured value satisfies the following characteristic (Y). That is, when two optical laminated bodies 7 are used, and the optical laminated bodies 7 are adhered to both surfaces of a glass plate so that the optical axes of the polarizing plates 4 of the optical laminated bodies 7 are orthogonal to each other, and the following (X) is measured. It is necessary that the measured values satisfy the following characteristic (Y).

(X) A laminate obtained by laminating the polarizing plate 4 on both surfaces of a glass plate was left in an atmosphere at 69 ° C. for 750 hours, and then the color coordinates in the vertical direction were measured at nine points in the plane by uniform division. X value and y value when performing.

(Y) Each of the minimum values of the x value and the y value is 0.2 or more, and the difference between the maximum value and the minimum value of the x value and the difference between the maximum value and the minimum value of the y value are Both are 0.1
Less than.

As the glass plate used in the measurement of the x value and the y value, a white plate glass generally used for forming a liquid crystal cell can be cited, its thickness is usually about 1.1 mm, and its transmittance is 99. About 5% is preferably used.

In the measurement of the x value and the y value of the present invention,
The x value and the y value when the color coordinates in the vertical direction of the laminate are measured at nine points in the plane are specifically referred to as follows. That is, the coordinate plane of the vertical color coordinates is set to the vertical (y
When the coordinate plane is divided into nine parts by equally dividing the coordinate plane into three parts in the (axis) direction and the horizontal (x-axis) direction, the x and y values at the center of each of the nine coordinate planes are referred to.

In the present invention, each of the minimum values of the x value and the y value needs to be 0.2 or more, but is preferably 0.2 to 0.3. That is, if one of the minimum values of the x value and the y value is less than 0.2, the use environment resistance of the liquid crystal display element is inferior.

In the present invention, it is necessary that the difference between the maximum value and the minimum value of the x value and the difference between the maximum value and the minimum value of the y value are both 0.1 or less. , 0 to 0.1. That is, if one of the difference between the maximum value and the minimum value of the x value and the difference between the maximum value and the minimum value of the y value is larger than 0.1, the use environment resistance of the liquid crystal display element is inferior. is there.

In the present invention, each of the minimum values of the x value and the y value is 0.2 or more, and the difference between the maximum value and the minimum value of the x value and the difference between the maximum value and the minimum value of the y value. May be set to 0.1 or less, for example, as described in the method for manufacturing the polarizing film 1,
After the iodine is adsorbed on the solution, the solution is treated with a solution containing boric acid having a concentration of 60 g / l or more and potassium iodide and stretched. Further, there may be mentioned a method of controlling with a washing treatment condition and a method of controlling with a gelation fraction of the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer.

The thus obtained optical laminate 7 of the present invention has excellent adhesion between the polarizing film 1 and the protective film 3 and therefore has improved durability and can be left for a long time in a high temperature and high humidity state. Also has the property that its polarization does not decrease,
Utilizing such characteristics, it is used for liquid crystal display devices, and is particularly useful for vehicles, various industrial instruments, display of household electric appliances, and the like.

Next, examples will be described together with comparative examples.

[0053]

Example 1 Average polymerization degree 3800, average saponification degree 99.
5 mol% of PVA was dissolved in water to obtain a 5.0 wt% solution. This solution was cast on a polyethylene terephthalate film and then dried to obtain a raw film having a thickness of 40 μm. This raw film was cut into a width of 10 cm and mounted on a chuck, immersed in an aqueous solution containing 0.2 g / l of iodine and 60 g / l of potassium iodide at 30 ° C. for 240 seconds, and then 60 g / l of boric acid. 30 g of potassium iodide
/ L of an aqueous solution having a composition of 6.0
A boric acid treatment was carried out for 5 minutes while being uniaxially stretched twice to produce a PVA film having a thickness of 20 μm. Next, this was washed with water at 20 ° C. for 90 seconds, and air-dried for
After drying for 4 hours, a polarizing film was obtained. Next, on both sides of this polarizing film, TAA was applied via a PVA-based adhesive.
The C film was laminated to obtain a polarizing plate. Then, an adhesive having a gelation fraction change value of 5% was prepared, and this adhesive was applied to one surface of the polarizing plate to form an adhesive layer having a thickness of 20 μm, thereby obtaining an optical laminate. As the pressure-sensitive adhesive, a pressure-sensitive adhesive containing butyl acrylate (BA) and acrylic acid (AAc) as main components (BA: AAc = 95: 5 (weight ratio)) and an isocyanate compound was used.

[0054]

Examples 2 to 6 and Comparative Examples 1 to 6 The concentration of boric acid, the conditions of the washing treatment and the change in the gelation fraction of the pressure-sensitive adhesive layer were changed as shown in Tables 1 and 2 below. . Otherwise in the same manner as in Example 1, an optical laminate was obtained.

Using the optical laminates of Examples 1 to 6 and Comparative Examples 1 to 6 obtained in this way, the x- and y-values and the visibility of the liquid crystal display element were compared according to the following criteria. An evaluation was performed. The results are shown in Tables 1 and 2 below.

[X value, y value] First, the above optical laminate was
In addition to preparing one glass plate, one glass plate was prepared. Next, the pressure-sensitive adhesive layer side of the optical laminate was adhered to both surfaces of the glass plate, respectively, to produce a laminate. In this case, 2
The polarizing plates of the optical laminates were adhered so that the optical axes were orthogonal to each other. Then, as described above, the above-described laminate was subjected to 6-layer measurement using an optical measurement device RETS2000 manufactured by Otsuka Electronics Co., Ltd.
After being left in an atmosphere at 9 ° C. for 750 hours, the x- and y-values were measured when the color coordinates in the vertical direction were measured at nine points in the plane.

[Visibility of Liquid Crystal Display Element] First, a liquid crystal display element (10.4 inch size, TFT type, number of pixels V
GA), the above-mentioned optical laminate after being left in an atmosphere at 69 ° C. for 750 hours was adhered to both sides of the liquid crystal display device to produce a liquid crystal display device. Ease of viewing was evaluated by 10 panelists. The results are indicated by ○ when five or more people were judged to be good, and × when less than five people were judged to be good.

[0058]

[Table 1]

[0059]

[Table 2]

From the results shown in Tables 1 and 2, Example 1 was obtained.
It can be seen that the visibility of the liquid crystal display element is superior when the optical laminates of the first to sixth products are used as compared with the case where the optical laminates of the first to sixth products are used. From this, the above x
Each of the minimum values of the value and the y value is 0.2 or more,
If the difference between the maximum value and the minimum value of the x value and the difference between the maximum value and the minimum value of the y value are all 0.1 or less, a decrease in visibility with respect to a change in the use environment can be suppressed, and It can be seen that the properties are improved.

[0061]

As described above, the optical laminate of the present invention is
At least on one side of the polarizing film, on the protective film side of the polarizing plate obtained by attaching a protective film via an adhesive layer,
An optical laminate on which an adhesive layer is formed. Two optical laminates are attached to both surfaces of a glass plate so that the optical axes of polarizing plates of the optical laminate are orthogonal to each other. When X) is measured, the measured value satisfies the characteristic (Y). For this reason, it is possible to suppress a decrease in visibility of the liquid crystal display element with respect to a change in the use environment, and to improve the use environment resistance. Therefore, the liquid crystal display device obtained by sticking the optical laminate has excellent visibility without a significant decrease in display characteristics due to a change in the use environment.

The polarizing film is obtained by treating an iodine-adsorbed polyvinyl alcohol-based film with a specific solution having a boric acid concentration, stretching the film, and washing with water. An optical laminate satisfying the above characteristic (Y) can be obtained by using a material in which the change value of the gelation fraction is set in a specific range.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the optical laminate of the present invention.

FIG. 2 is a sectional view showing one embodiment of the liquid crystal display device of the present invention.

FIG. 3 is a sectional view showing one embodiment of the liquid crystal display device of the present invention.

FIG. 4 is a partially cutaway perspective view showing a color STN liquid crystal display module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polarizing film 2 Adhesive layer 3 Protective film 4 Polarizing plate 5 Adhesive layer 7 Optical laminated body

Claims (4)

[Claims] 1. An optical laminate comprising a polarizing plate having a protective film adhered to at least one surface of a polarizing film via an adhesive layer and having a pressure-sensitive adhesive layer formed on the protective film surface side. When two laminates were used and attached to both sides of a glass plate so that the optical axes of the polarizing plates of the optical laminate were perpendicular to each other, and the following (X) was measured, the measured value was the following characteristic (Y An optical laminate characterized by satisfying (1). (X) The laminate obtained by adhering the above-mentioned polarizing plate to both surfaces of a glass plate was left in an atmosphere at 69 ° C. for 750 hours, and the color coordinate in the vertical direction was measured at nine points in the in-plane uniform division. Value and y value. (Y) Each of the minimum values of the x value and the y value is 0.2
And the difference between the maximum and minimum x values and y
The difference between the maximum value and the minimum value is 0.1 or less. 2. The method according to claim 1, wherein the polarizing film comprises a polyvinyl alcohol-based film on which iodine is adsorbed and a concentration of 60 g / l.
The optical laminate according to claim 1, wherein the laminate is treated with a solution containing boric acid and potassium iodide, stretched, and then washed with water at 20 ° C for 90 seconds. 3. The optical laminate according to claim 1, wherein the change in the gelation fraction of the pressure-sensitive adhesive layer after the heat treatment at 69 ° C. for 750 hours is set in the range of 5 to 20%. 4. A liquid crystal display device wherein the optical laminate according to claim 1 is adhered to at least one surface of a liquid crystal cell via the adhesive layer.