JP3963405B2 - Manufacturing method of polarizing plate - Google Patents

Description

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【００３９】
【表３】

【００４０】
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【発明の効果】
本発明の偏光板の製造においては、原反フィルムの延伸時と偏光フィルムと保護フィルムのラミネート時又はラミネート後に特定の加圧処理を施しているため、原反フィルム延伸時の加圧が線圧力が１５０〜２００００ｋｇ／１ｍ幅であり、偏光フィルムに保護フィルムをラミネートする時、又はラミネート後に、加圧が線圧力が１０〜２０００ｋｇ／１ｍ幅で、加圧温度が５〜１１０℃であるため、光学性能むらと厚みむらが少なく、光学性能に秀で、視認性に優れ、耐久性にも優れた偏光板が得られ、該偏光板は、電子卓上計算機、電子時計、ワープロ、自動車や機械類の計器類等の液晶表示装置として有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polarizing plate, and more specifically, polarized light that has less optical performance (transmittance, polarization degree, color tone) unevenness and thickness unevenness, excellent optical performance, excellent visibility, and excellent durability. The present invention relates to a method for manufacturing a plate.
[0002]
[Prior art]
In recent years, liquid crystal display devices have been used in desktop electronic computers, electronic watches, word processors, automobile and mechanical instruments, and polarizing plates have been used in liquid crystal display devices. A polarizing plate is composed of a polarizing film obtained by uniaxially stretching a polyvinyl alcohol film, a protective film, and the like. Usually, when a polarizing film is produced, stretching is performed together with dyeing of a polarizing material. Unevenness and unevenness in thickness occur. For example, in terms of transmittance as the optical performance, in the thickness direction, the transmittance and thickness at both ends are darker than the transmittance and thickness at the both ends. Thick. In other words, the current situation is that the polarizing film is manufactured with uneven stretching in the width direction.
[0003]
[Problems to be solved by the invention]
When the polarizing film is stretched, if it is stretched, the optical performance increases. However, the molecular orientation of the polarizing film itself increases and the shrinkage increases, so that when the polarizing plate is mounted on the liquid crystal display device, the liquid crystal The visibility and durability of the display device are significantly reduced. Under such a background, the present invention provides a method for producing a polarizing plate that exhibits little optical performance unevenness and thickness unevenness, excellent optical performance, excellent visibility, and excellent durability. Objective.
[0004]
[Means for Solving the Problems]
However, as a result of intensive studies to solve such problems, the present inventor made a linear pressure of 150 to 20000 kg / 1 m width during stretching of the raw film and produced a protective film on the polarizing film. When laminating, or when pressure treatment is performed under the condition that the linear pressure after lamination is 10 to 2000 kg / 1 m width and the temperature during lamination or linear pressure after lamination is 5 to 110 ° C. effect be exhibited, according to a further stretching, when a proximity stretching or width fixed stretching, and have completed the present invention found that can be particularly pronounced effects of the present invention. In the present invention, a film imparted with polarizing performance by adsorption orientation of an iodine compound is referred to as a “polarizing film”, and when a protective film is provided on both sides or one side of the “polarizing film”, it is referred to as a “polarizing plate”. Distinguish.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described.
[0006]
The raw film used for the polarizing plate of the present invention is not particularly limited, but a polyvinyl alcohol film is preferable, and such polyvinyl alcohol is usually produced by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. The invention is not necessarily limited to this, and can be copolymerized with vinyl acetate such as a small amount of unsaturated carboxylic acid (including salts, esters, amides, nitriles, etc.), olefins, vinyl ethers, unsaturated sulfonates, etc. It may contain various components. The saponification degree of the polyvinyl alcohol used in the present invention is preferably a high saponification degree in terms of durability, particularly in terms of improving heat resistance. That is, the average degree of saponification is 85 to 100 mol%, preferably 98 to 100 mol%, particularly 99 to 100%. The average degree of polymerization of polyvinyl alcohol used in the present invention is required to be 1700 or more, preferably 5600 to 10000, more preferably 6500 to 9000, which is excellent in transmittance, polarization degree, and color tone.
[0007]
As a method for producing an original film, first, an undiluted solution obtained by dissolving polyvinyl alcohol in water or an organic solvent is cast into a film to produce a polyvinyl alcohol-based original film. Water is mainly used as a solvent for preparing the stock solution for film formation at that time, but dimethyl sulfoxide (DMSO), N-methylpyrrolidone, glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetra Polyhydric alcohols such as ethylene glycol and trimethylolpropane, amines such as ethylenediamine and diethylenetriamine, and mixtures thereof may be used, and a small amount, for example, 5 to 30% by weight of water may be contained in the above substance. Absent.
[0008]
The concentration of polyvinyl alcohol in the stock solution is practically 2 to 20% by weight. The polyvinyl alcohol film-forming stock solution obtained using the solvent is formed by an arbitrary method such as a casting method or an extrusion method. As a film forming method, a dry / wet film forming method is used, that is, the solution is once discharged into air or an inert atmosphere such as nitrogen, helium, argon, etc. from the nozzle slit, and then introduced into a coagulation bath. A stretched film is formed. Alternatively, the film-forming solution discharged from the die may be introduced into the coagulation bath after the solvent is partially dried on a roller or a belt conveyor.
[0009]
The solvent used in the coagulation bath is miscible with the polyvinyl alcohol solvent, and examples thereof include alcohols such as methanol, ethanol, propanol and butanol, acetone, benzene and toluene.
As a method for obtaining a polyvinyl alcohol-based film, a so-called gel film forming method in which a solution of polyvinyl alcohol is introduced into a coagulation bath to form a film can be performed.
The film thickness of the raw film is required to be 10 to 100 μm, preferably 50 to 90 μm. If the thickness is less than 10 μm, the film cannot be stretched. If the thickness exceeds 100 μm, the film thickness accuracy is lowered, which is inappropriate.
[0010]
Next, the obtained polyvinyl alcohol-based raw film is subjected to a treatment such as stretching to become a polarizing film, but is preferably swollen with water in advance, and the swelling is 1 at 5 to 30 ° C. For 10 minutes. In the present invention, in this stretching treatment step, the first characteristic is that the linear pressure is 150 to 20000 kg / 1 m width, thereby suppressing the thickness unevenness and the transmittance unevenness in the width direction. . A specific method of the pressurization is not particularly limited, but practically, when stretching the raw film, two or more sandwiching the raw film is added by two or more pinch nip rolls or mangle rolls. Pressure is used. Shafts and bearings having a diameter smaller than the roll diameter are arranged at both ends of these rolls, and stretching is performed by applying a driving force to these shafts and simultaneously applying pressure to the bearings. The linear pressure refers to the force (kg) between which the film is sandwiched between these rolls converted to a 1 m width of the film. When the linear pressure is less than 150 kg / 1 m width, the thickness unevenness and the transmission in the width direction are transmitted. When unevenness of rate occurs and exceeds 20000 kg / 1 m width, the structure in the polarizing film is destroyed and the degree of polarization is lowered.
[0011]
With respect to the stretching ratio, if the stretching ratio is increased too much, the molecular orientation of the polyvinyl alcohol / boron cross-linked substrate in the polarizing film increases. Therefore, it is desirable to stretch at a low magnification of 3.0 times or less. Furthermore, as for the stretching method at this time, it is necessary to stretch in the uniaxial direction, but it is more preferable to stretch by proximity stretching or fixed width stretching. The proximity stretching means a stretching treatment in which the ratio of the length of the stretching roll interval to the length of the film width is 1 or less (excluding 0), and the fixed width stretching refers to a pinch guider, a cross guider, and a tenter. It means a process of holding the ear end using a clip, an expander roll, a spiral roll or the like, or stretching while preventing expansion of the ear end in the width direction while spreading in the width direction.
[0012]
The raw film of the present invention is subjected to a stretching treatment as described above. In addition to this, a dyeing treatment, a boron compound treatment or the like is applied to obtain a polarizing film. Such dyeing treatment (that is, adsorption of the polarizing element) is performed by bringing the liquid containing the polarizing element into contact with the raw film by any means such as dipping, coating, spraying, and the like. Iodine staining is performed by immersion treatment with an aqueous solution of potassium halide. In this case, the iodine-potassium iodide aqueous solution had an iodine concentration of 0.1 to 0.45 g / l, a potassium iodide concentration of 10 to 50 g / l, and an iodine / potassium iodide weight ratio of 20. An aqueous solution of ~ 100 is used. A small amount of boric acid and borax can be added to the iodine-potassium iodide aqueous solution, and a small amount of an organic solvent compatible with water can be contained in addition to the aqueous solvent. In addition, about this dyeing | staining processing condition, time is about 30-1000 second, and the temperature of a processing bath is 5-35 degreeC practical.
[0013]
Such a boron compound treatment is a treatment in which a raw film is brought into contact with a boron compound such as boric acid or borax by a dipping method, a coating method, a spraying method or the like, and a dipping method is practically used. The boron compound used here is used in the form of an aqueous solution or a water-organic solvent mixed solution at a concentration of about 0.5 to 2 mol / l. In the solution, a small amount of iodine of about 0.1 to 25 ppm and 20 to 70 g are used. / L of potassium iodide is preferably present together. The treatment conditions here are practically a treatment temperature of about 45 to 70 ° C. and a treatment time of about 5 to 20 minutes.
[0014]
The dyeing treatment, the boron compound treatment and the stretching treatment can be arbitrarily performed. For example, the raw film is first stretched and then dyed and then boron compound treated, or the dyeing treatment and stretching. Doing the treatment at the same time, stretching treatment after the dyeing treatment, and then treating with the boron compound, or after the dyeing treatment, stretching in the boron compound treatment, or during the dyeing treatment and in the boron compound treatment, split stretching treatment, Although it is not particularly limited, a method of split stretching treatment during dyeing treatment and boron compound treatment is preferable. The stretching ratio may be finally set within the above range, and the stretching operation may be performed not only in one stage but also in any stage of the manufacturing process.
[0015]
In the above boron compound treatment, a water washing treatment such as immersion, spraying, coating, etc. for 2 minutes or less is usually performed at 2 to 30 ° C., followed by a drying treatment at a temperature of 30 to 90 ° C. for 30 to 500 seconds. However, preferably, the optical performance is remarkably improved by performing the drying treatment after the washing treatment and the re-dying treatment. For the re-dyeing treatment, an aqueous solution of iodine-potassium iodide is used. The concentration of iodine is 0.1 to 0.9 g / l, the concentration of potassium iodide is 10 to 50 g / l, and the dyeing time is 10 to 10 g / l. For 500 seconds, a treatment bath temperature of 5 to 30 ° C. is practical.
[0016]
Thus, the thickness direction was controlled by pressurization during stretching, and the longitudinal direction and width direction were controlled by stretching 3 times or less and proximity stretching or width fixed stretching, that is, the stretching thickness direction, longitudinal direction, width direction 3 Three-dimensional control of direction, non-uniformity in transmittance and thickness, excellent transmittance, degree of polarization, color tone, excellent viewing angle, visibility, small shrinkage, and excellent durability However, the thinner polarizing film after stretching is more preferable in view angle, visibility and shrinkage, and durability, and 1 to 15 μm is particularly preferable.
[0017]
Next, a cellulose acetate-based protective film excellent in optical transparency and mechanical strength is bonded to both surfaces or one surface (preferably both surfaces) of the obtained polarizing film to form a polarizing plate. Examples of the cellulose acetate-based protective film include cellulose acetate-based films, acrylic films, polyester-based films, polyolefin-based films, polycarbonate-based films, polyetheretherketo-based films, and polysulfone-based films. Cellulose acetate-based films such as cellulose film and cellulose triacetate film are used. Optimally, cellulose triacetate film (for example, TD80U manufactured by Fuji Film Co., Ltd.) that changes the distribution of the lubricant on the film surface and suppresses shrinkage after the durability test is preferable. . Furthermore, it is also possible to mix | blend ultraviolet absorbers, such as a salicylic acid ester type compound, a benzophenol type compound, a benzotriazole type compound, a cyanoacrylate type compound, a nickel complex salt type compound, with the said resin film as needed.
[0018]
In addition, it is effective to saponify the surface of the protective film with alkali and then further heat-treat, plasma treatment, glow discharge treatment, corona discharge treatment, high frequency treatment, electron beam treatment, etc. before bonding. However, the tension during the treatment is preferably low, and it is practical to carry out at a width of 0.5 to 10 kg / 1 m.
[0019]
In the present invention, when the protective film for the polarizing film is laminated (bonding treatment) or after the lamination, the pressure treatment is performed under the conditions that the linear pressure is 10 to 2000 kg / 1 m width and the pressure temperature is 5 to 110 ° C. The second characteristic is that a polarizing plate with small shrinkage and excellent durability can be obtained by such treatment. Specifically, at the time of laminating, it is laminated together with pressure treatment by a hot air or hot air air knife (air slit) or a laminating roll of dielectric heating method or steam heating method, and after lamination, feed of dielectric heating method or steam heating method is performed. Pressurized with a pinch roll. Pressurization is controlled by the pressure of the warm air or hot air and the air volume when using an air knife. When using a laminating roll or feed pinch roll, the pressure is controlled by applying force to the roll in the same way as the stretching roll. The The temperature of the pressure treatment is controlled by the temperature of the air used with hot air or hot air in the case of an air knife, controlled by the energized voltage and current in the case of the dielectric heating method, and in the case of the steam heating method, It is controlled by the steam pressure used.
[0020]
For the bonding of the laminate between the polyvinyl alcohol polarizing film and the protective film, an adhesive such as polyvinyl alcohol, urethane, or acrylic is used, preferably a polyvinyl alcohol adhesive having a high degree of polymerization and saponification. . In addition, regarding such lamination, one side may be laminated sequentially or both sides may be laminated at the same time. When the polarizing film and the protective film are bonded, it is necessary to lower the tension of each film, preferably 0. It is practical to carry out at a width of 5 to 10 kg / 1 m (tension). After the bonding, drying and heat treatment are performed, and the temperature is 35 to 100 ° C., preferably 65 to 90 ° C., for 1 to 10 minutes.
[0021]
Regarding the conditions at the time of lamination of the polarizing plate or after lamination, the linear pressure here is the same as that at the time of stretching, and the force sandwiched between them is converted to 1 m width, and the linear pressure is less than 10 kg / 1 m width. In this case, there is no effect on shrinkage and durability, and if the width exceeds 2000 kg / 1 m, poor appearance of the polarizing plate is generated, or conversely shrinkage and durability are deteriorated. When the pressurization temperature is less than 5 ° C, the appearance of the polarizing plate is deteriorated due to condensation, and the shrinkage and durability are deteriorated. When the temperature exceeds 110 ° C, the protective film is damaged and the appearance of the polarizing plate is deteriorated. Cause poor color tone and lower polarization degree.
[0022]
In addition, when laminating, the same effect can be obtained even if the above conditions are processed after the lamination without performing the above conditions. When the heat treatment is performed, a polarizing plate having further reduced shrinkage and excellent durability can be obtained. The pressure and heat treatment after lamination are not particularly limited before or after drying and heat treatment.
[0023]
With a manufacturing method that makes it difficult to obtain polarizing plates with little optical performance unevenness and thickness unevenness, excellent optical performance, excellent visibility, small shrinkage, and excellent durability, word processors, televisions, personal computers, cars It is suitable for a liquid crystal display for uses such as navigation.
[0024]
【Example】
Next, an example is given and it demonstrates in detail.
In the examples, “%” is based on weight unless otherwise specified.
Example 1
Polyvinyl alcohol having an average polymerization degree of 8000 and a saponification degree of 99.6 mol% was dissolved in water to obtain a 2.0% solution. The solution was cast on a polyethylene terephthalate film and then dried to obtain a raw film (55 μm, width 1000 mm). The film was immersed in an aqueous solution consisting of 0.25 g / l iodine and 60 g / l potassium iodide at 20 ° C. for 340 seconds, then boric acid 50 g / l, potassium iodide 60 g / l, iodine 2 ppm. While being immersed in an aqueous solution, boric acid treatment was performed for 10 minutes while simultaneously performing fixed width uniaxial stretching at 3.0 times at 52 ° C. In addition, this extending | stretching was performed with the extending | stretching roll of diameter 250mm, and the linear pressure of the pressurization at that time was 10000 kg / 1m width. Next, after being immersed in a 7 ° C. water-washing tank for 4 seconds, it was immersed in an aqueous solution of iodine 0.15 g / l and potassium iodide 20 g / l for 15 seconds at 15 ° C., and then at 55 ° C. for 2 minutes. It dried and the polarizing film of width 980mm was obtained. Next, a cellulose triacetate film (Fuji Film Co., Ltd. TD80U) is applied to both sides of the obtained polarizing film, and each tension is 1 kg / 1 m width and a pressurizing line using a dielectric heating system roll having a diameter of 250 mm. After the pressure is 1000 kg / 1 m width, the pressing temperature is 50 ° C., and a polyvinyl alcohol adhesive (NH26, 4% aqueous solution manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) is adhered, and then dried at 90 ° C. for 3 minutes. Again, a polarizing plate (1) was obtained with the same roll as described above by applying a pressure of 1000 kg / 1 m width and a pressure of 50 ° C.
[0025]
The obtained polarizing plate (1) was cut into a full length in the width direction (980 mm in this example) and a longitudinal length (300 mm) to obtain polarizing plate (1) -A for evaluation.
On the back and front of white glass (made of Matsunami glass, thickness 1.1 mm, A4 size), a polarizing plate (1) (A4 size) was bonded to the cross Nicol (orthogonal) position via an acrylic adhesive. A glass sample (1) -B for evaluation was obtained.
A liquid crystal display device for evaluation by bonding the polarizing plate (1) to an upper polarizing plate and a lower polarizing plate outside a TFT liquid crystal display device (a liquid crystal display device in NEC PC9821Ne3) via an acrylic adhesive. (1) -C was obtained.
The obtained polarizing plate (1) was evaluated as follows.
[0026]
・ (Thickness unevenness)
Using (1) -A, the thickness at a point 5 mm from the edge of the ear and a point 450 mm from the edge (that is, approximately the center point) was measured using a digital linear gauge PDN12 continuous thickness meter manufactured by Ozaki Company (unit: μm).
・ (Optical performance and optical performance unevenness)
Using (1) -A, the optical performance (transmittance, degree of polarization, color tone) at a point 5 mm from the edge of the ear and a point 450 mm from the edge (that is, approximately the center point) is measured by Otsuka Electronics MCPD: RETS2000 Measurement was performed using a measurement method based on EIAJ ED-2521 of the industry association standard.
[0027]
・ (Shrink)
(1) -A was left as it was at 85 ° C. for 3 days, and the change in the contraction length in the diagonal direction was measured as a percentage of the original length.
·(durability)
Using (1) -B, after measuring the x value and the y value by Otsuka Electronics MCPD: RETS2000 at 5 mm and 5 mm from the corners of the four corners and the center point of the diagonal line, the (1) -B Were subjected to a heat resistance test at 65 ° C. and 90% RH for 10 days and a heat resistance test at 85 ° C. for 10 days, the x value and the y value were measured, and the absolute value of the difference was calculated.
·(Visibility)
Comparison of the increase and decrease of the viewing angle at the center of the diagonal line of (1) -C panel, with the vertical and horizontal viewing angles of the polarizing plate attached to the liquid crystal display element in NEC PC9821Ne3 as 0 degrees. (Unit angle °).
[0028]
Example 2
Polyvinyl alcohol having an average polymerization degree of 4000 and a saponification degree of 99.7 mol% was dissolved in water to obtain a 3.0% solution. The solution was cast on a polyethylene terephthalate film and then dried to obtain a raw film (75 μm, width 1000 mm). The film was immersed in an aqueous solution of 0.28 g / l iodine and 20 g / l potassium iodide at 17 ° C. for 360 seconds, and then boric acid 53 g / l, potassium iodide 65 g / l, iodine 4 ppm in composition. While being immersed in an aqueous solution, boric acid treatment was performed for 10 minutes while simultaneously performing uniaxial stretching with a fixed width of 4.5 times at 53 ° C. In addition, this extending | stretching was performed with the extending | stretching roll with a diameter of 250 mm, and the linear pressure of the pressurization at that time was 9000 kg / 1m width. Next, after immersing in a 3 ° C. water-washing tank for 4 seconds, it was immersed in an aqueous solution of iodine 0.25 g / l and potassium iodide 15 g / l for 19 seconds at 10 ° C., and then at 45 ° C. for 3 minutes. It dried and the polarizing film of width 980mm was obtained. Next, a cellulose triacetate film (TD80U manufactured by Fuji Film Co., Ltd.) is applied to both sides of the obtained polarizing film, and each tension is 0.5 kg / 1 m width and pressurized by a dielectric heating system roll manufactured by Yuri Roll Co., Ltd. Adhesion with a polyvinyl alcohol adhesive (NH17, 2.7% aqueous solution manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) at a pressure of 80 ° C. and a linear pressure of 1300 kg / 1 m width, followed by 4 minutes at 85 ° C. After drying, the film was again treated with the same roll as described above at a pressure linear pressure of 1000 kg / 1 m width and a pressure temperature of 50 ° C. to obtain polarizing plate (2).
The obtained polarizing plate (2) was evaluated in the same manner as in Example 1 with respect to (2) -A, (2) -B, and (2) -C.
[0029]
Comparative Example 1
Polyvinyl alcohol having an average polymerization degree of 1700 and a saponification degree of 99.9 mol% was dissolved in water to obtain a 7.0% solution. The solution was cast on a polyethylene terephthalate film and then dried to obtain a raw film (80 μm, width 1000 mm). The film was immersed in an aqueous solution consisting of 0.22 g / l iodine and 30 g / l potassium iodide at 23 ° C. for 380 seconds, and then boric acid 55 g / l, potassium iodide 55 g / l, iodine 9 ppm. While being immersed in an aqueous solution, boric acid treatment was performed for 6 minutes while simultaneously stretching the width by 7.5 times at 50 ° C. In addition, this extending | stretching was performed with the extending | stretching roll of diameter 250mm, and the linear pressure of the pressurization at that time was 70 kg / 1m width. Next, after being immersed in a 20 ° C. water-washing tank for 20 seconds, it was immersed in an aqueous solution consisting of iodine 0.35 g / l and potassium iodide 35 g / l at 20 ° C. for 30 seconds, and then dried at room temperature for 3 minutes. A polarizing film having a width of 420 mm was obtained. Next, a cellulose triacetate film (TD80U manufactured by Fuji Film Co., Ltd.) is applied to both sides of the obtained polarizing film, and each tension is 20 kg / 1 m width and a pressurizing line by using a dielectric heating system roll having a diameter of 250 mm manufactured by Yuri Roll Co., Ltd. The pressure was 23 kg / 1 m width, the pressing temperature was 30 ° C., and it was adhered with a polyvinyl alcohol adhesive (NL05, 3.7% aqueous solution manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), and then dried at 45 ° C. for 4 minutes. Then, again, with the same roll as above, the pressure was applied at a pressure of 15 kg / 1 m and the pressure was 50 ° C. to obtain a polarizing plate (3).
The obtained polarizing plate (3) was evaluated in the same manner as in Example 1 with respect to (3) -A, (3) -B, and (3) -C.
[0030]
Comparative Example 2
In Example 1, a polarizing plate (4) was obtained in the same manner as in Example 1 except that the linear pressure during stretching was changed from 10000 kg / 1 m width to 50 kg / 1 m width.
The obtained polarizing plate (4) was evaluated in the same manner as in Example 1 with respect to (4) -A, (4) -B, and (4) -C.
[0031]
Comparative Example 3
In Example 1, a polarizing plate (5) was obtained in the same manner as in Example 1 except that the linear pressure applied during stretching was changed to 30,000 kg / 1 m width instead of 10,000 kg / 1 m width.
The obtained polarizing plate (5) was evaluated in the same manner as in Example 1 with respect to (5) -A, (5) -B, and (5) -C.
[0032]
Comparative Example 4
In Example 1, a polarizing plate (6) was obtained in the same manner as in Example 1 except that the linear pressure applied during lamination was changed from 1000 kg / 1 m width to 6 kg / 1 m width.
The obtained polarizing plate (6) was evaluated in the same manner as in Example 1 with respect to (6) -A, (6) -B, and (6) -C.
[0033]
Comparative Example 5
In Example 1, a polarizing plate (7) was obtained in the same manner as in Example 1 except that the linear pressure during lamination was changed to 1000 kg / 1 m width and changed to 6000 kg / 1 m width. The obtained polarizing plate (7) was evaluated in the same manner as in Example 1 with respect to (7) -A, (7) -B, and (7) -C.
[0034]
Comparative Example 6
In Example 1, a polarizing plate (8) was obtained in the same manner as in Example 1 except that the pressing temperature at the time of lamination was changed to 3 ° C. instead of 50 ° C.
The obtained polarizing plate (8) was evaluated in the same manner as in Example 1 with respect to (8) -A, (8) -B, and (8) -C.
[0035]
Comparative Example 7
In Example 1, a polarizing plate (9) was obtained in the same manner as in Example 1 except that the pressing temperature during lamination was changed to 50 ° C. and changed to 120 ° C.
The obtained polarizing plate (9) was evaluated in the same manner as in Example 1 with respect to (9) -A, (9) -B, and (9) -C.
[0036]
The evaluation result of an Example and a comparative example is shown to Tables 1-5. Table 1 shows thickness unevenness, Table 2 shows optical performance and optical performance unevenness, Table 3 shows shrinkage, Table 4 shows durability, and Table 5 shows viewing angle.
[0037]
[Table 1]

[0038]
[Table 2]

[0039]
[Table 3]

[0040]
[Table 4]

[0041]
[Table 5]

[0042]
【The invention's effect】
In the production of the polarizing plate of the present invention, since a specific pressure treatment is applied at the time of stretching the raw film and at the time of laminating the polarizing film and the protective film or after the lamination, the pressure at the time of stretching the raw film is a linear pressure. Is 150 to 20000 kg / 1 m width, and when the protective film is laminated on the polarizing film, or after lamination, the pressure is 10 to 2000 kg / 1 m width and the pressing temperature is 5 to 110 ° C. There is little optical performance unevenness and thickness unevenness, excellent optical performance, excellent visibility, and excellent polarizing plate can be obtained. This polarizing plate is an electronic desk calculator, electronic clock, word processor, automobile and machinery. It is useful as a liquid crystal display device for such instruments.

Claims (2)

  In producing a polarizing plate, the linear pressure during stretching of the raw film is 150 to 20000 kg / 1 m width, and when the protective film is laminated on the polarizing film, or the linear pressure after lamination is 10 to 2000 kg / 1 m width. A method for producing a polarizing plate, wherein pressure treatment is performed under a condition that the temperature at the time of linear pressure after lamination is 5 to 110 ° C. Stretching the raw film, method of producing the polarizing plate according to claim 1 Symbol mounting, characterized in that a proximity stretching or fixed width stretching.