TW201732326A - Polarizing plate and liquid crystal panel - Google Patents

Abstract

The present invention provides a polarizing plate which is possible to suppress a decrease in degree of polarization due to deviation of an absorption axis of a polarizing film caused by dimensional change of an optical film stretched during a heat resistance test. The polarizing plate comprises a stretched optical film, a first protective film, a polarizing film and an adhesive layer in this order, wherein an angle between the absorption axis of the polarizing film and the slow axis of the optical film stretched is about 45 DEG or about 135 DEG; when the first protective film placed in an environment of 85 DEG C for 100 hours, it has a dimensional change rate D1 in a direction of 45 DEG with respect to the absorption axis of the polarizing film, and a dimensional change rate D2 in a direction of 135 DEG with respect to the absorption axis of the polarizing film, and D1 and D2 satisfy the following formulas (1) and (2): In the case of | D1 | ≥ | D2 |, 1 ≤ | D1 | / | D2 | ≤ 2 ...(1) In the case of | D1 | < | D2 |, 1 < | D2 | / | D1 | ≤ 2 ...(2).

Description

Polarizer and LCD panel

The present invention relates to a polarizing plate and a liquid crystal panel using the same.

In recent years, liquid crystal displays that consume low power, operate at low voltage, and are lightweight and thin have been rapidly popularized as information display devices such as mobile phones, portable information terminals, computer screens, and televisions. Along with the development of liquid crystal technology, various forms of liquid crystal displays have been proposed, and problems such as reaction speed and contrast, narrow viewing angle, and the like are continuing to be solved. Further, with the spread of portable liquid crystal displays, for example, when used outdoors, there is a case where the liquid crystal display screen is viewed in a state in which polarized sunglasses are worn, and in this case, the liquid crystal display is also required. Even if you look at the picture through polarized sunglasses, it is still excellent.

In the past, several means for improving the visibility when viewing a screen through polarized sunglasses have been proposed (Patent Documents 1 to 9).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-122454

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-107198

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2011-215646

[Patent Document 4] Japanese Laid-Open Patent Publication No. 2012-230390

[Patent Document 5] Japanese Patent Laid-Open Publication No. 03-174512

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2013-231761

[Patent Document 7] Japanese Laid-Open Patent Publication No. 2011-113018

[Patent Document 8] Japanese Patent Laid-Open Publication No. 2013-182162

[Patent Document 9] Japanese Patent Laid-Open Publication No. 2013-200445

The method for improving the visibility when viewing a screen through polarized sunglasses is to convert linearly polarized light emitted from a polarizing plate disposed on the viewing side of an image display element such as a liquid crystal cell into A method of disposing a phase difference plate (for example, a λ/4 wavelength plate) on the viewing side of the polarizing plate by polarizing a circle (or a circle) (Patent Documents 1 to 9).

However, such a phase difference plate is often laminated to the polarizing film directly after being stretched. Moreover, the angle formed by the absorption axis of the polarizing plate and the slow axis of the phase difference plate is often set to a predetermined angle (for example, 45°), and when the polarizing plate is put into a heat resistance test, there is a phase difference plate extending through the extension plate. The oblique dimension changes to cause a local change in the absorption axis of the polarizing film and a problem of lowering the degree of polarization.

[1] A polarizing plate comprising: an extended optical film, a first protective film, a polarizing film, and an adhesive layer; wherein, an absorption axis of the polarizing film and a slow axis of the extended optical film The angle of formation is about 45° or about 135°; and the first protective film is 45° with respect to the absorption axis of the polarizing film after the first protective film is allowed to stand in an environment of 85° C. for 100 hours. When the dimensional change rate in the direction is D1 and the dimensional change rate in the direction of 135° with respect to the absorption axis of the polarizing film is D2, the following formula (1) and formula (2) are satisfied: |D1 |≧|D2|, 1≦|D1|/|D2|≦2...(1) |D1|<|D2|,1<|D2|/|D1|≦2...(2)

[2] The polarizing plate according to [1], wherein the stretched optical film comprises a cyclic polyolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin, and (meth) At least one selected from the group consisting of acrylic resins.

[3] The polarizing plate according to [1], wherein the polarizing film has a thickness of 15 μm or less.

[4] The polarizing plate according to any one of [1] to [3] further comprising a second protective film between the polarizing film and the adhesive layer.

[5] A liquid crystal panel according to any one of [1] to [4], wherein the polarizing plate according to any one of [1] to [4] is disposed on at least one surface of the liquid crystal cell.

According to the present invention, it is possible to provide a polarizing plate which is resistant to dimensional changes of an extended optical film when subjected to a heat resistance test. The resulting polarizing film absorbs the axis shift and the degree of polarization is lowered.

10‧‧‧Polar plate

11‧‧‧Extended optical film

12‧‧‧Adhesive layer

13‧‧‧1st protective film

14‧‧‧ polarizing film

15‧‧‧2nd protective film

16‧‧‧Adhesive layer

20‧‧‧Surface treatment layer

21‧‧‧An angle of 45° with respect to the absorption axis of the polarizing film

22‧‧‧ 135° angle with respect to the absorption axis of the polarizing film

30‧‧‧Absorption axis of polarizing film

Fig. 1 is a view showing an example of a schematic cross-sectional view of a layer configuration of a polarizing plate of the present invention.

Fig. 2 is an example of a plan view of a polarizing plate of the present invention.

The layer configuration of the polarizing plate 10 of the present invention will be described with reference to Fig. 1 . The polarizing plate of the present invention is formed by sequentially laminating the stretched optical film 11, the first protective film 13, the polarizing film 14, and the adhesive layer 16. The angle formed by the absorption axis of the polarizing film 14 and the slow axis of the optical film 11 is preferably about 45 or about 135. It is also useful to form the surface treatment layer 20 on the surface of the optical film 11 opposite to the surface on which the first protective film is bonded.

Further, the optical film 11 preferably contains at least one film selected from the group consisting of a cyclic polyolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin, and a (meth)acrylic resin. . Further, from the viewpoint of reducing the anisotropy of the dimensional change of the polarizing plate at the time of the heat resistance test, the first protective film 13 is preferably a film which is substantially not stretched.

The term "substantially unextended" as used herein means that the stretching ratio in any direction in the film plane is 1.1 times or less, preferably 1.05 times or less. Or, from another point of view, it means that the phase difference in the plane of the film is 20 nm or less at a wavelength of 590 nm.

According to the invention, it can also be provided on the polarizing film 14 and adhered The polarizing plate 10 of the second protective film 15 is further provided between the agents 16.

According to the present invention, there is still provided a liquid crystal panel in which the polarizing plate 10 is laminated on at least one side of the liquid crystal cell via the adhesive layer 16.

In the polarizing plate of the present invention, when the first protective film 13 is provided between the optical film 11 and the polarizing film 14, the ratio of the thickness of the stretched optical film 11 to the thickness of the polarizing film 14 is 1.5 or more. When it is 3 or more, the decrease in the degree of polarization can be effectively suppressed. The ratio of the thickness of the stretched optical film 11 to the thickness of the polarizing film 14 is usually 10 or less.

Hereinafter, the members constituting the liquid crystal display device of the present invention will be described in detail.

[Polarizing film 14]

The polarizing film 14 is usually produced by a step of stretching a polyvinyl alcohol-based resin film on one axis, a step of dyeing a polyvinyl alcohol-based resin film with a dichroic dye to adsorb a dichroic dye, and adsorbing The step of treating the polyvinyl alcohol-based resin film of the dichroic dye with a boric acid aqueous solution and crosslinking; and subjecting the mixture to a water-washing treatment after crosslinking treatment with an aqueous boric acid solution.

The polyvinyl alcohol-based resin can be produced by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Other monomers copolymerizable with vinyl acetate include, for example, unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and ammonium groups. Acrylamides and the like.

The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal modified with aldehydes, polyvinyl acetal or the like may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually from about 1,000 to 10,000, preferably from about 1,500 to 5,000.

A film formed of such a polyvinyl alcohol-based resin can be used as an original film of a polarizing film. The method of forming the film of the polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a known method. The film thickness of the polyvinyl alcohol-based resin original film is, for example, about 10 to 100 μm, preferably about 10 to 50 μm.

One of the stretching of the polyvinyl alcohol-based resin film can be carried out before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. When a shaft extension is performed after dyeing, the one-axis extension can be carried out before the boric acid treatment or in the boric acid treatment. Of course, one-axis extension can also be performed at a plurality of stages as shown here. In the one-axis extension, a method of extending on one axis between rolls having different rotational speeds, or a method of extending on one axis using a heat roll may be employed. Further, the one-axis extension can be carried out by dry stretching in which the film is stretched in the air, or can be carried out by wet stretching in which the polyvinyl alcohol-based resin film is swollen using a solvent such as water. The stretching ratio is usually about 3 to 8 times.

The dyeing of the polyvinyl alcohol-based resin film by the dichroic dye can be performed, for example, by immersing the polyvinyl alcohol-based resin film in the second The method in the aqueous solution of the coloring pigment is carried out. Specifically, iodine or a dichroic organic dye can be used as the dichroic dye. Moreover, it is preferable that the polyvinyl alcohol-based resin film is subjected to a treatment of immersing in water and swelling it before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide and dyed is usually used.

The iodine content in the aqueous solution is usually about 0.01 to 1 part by weight based on 100 parts by weight of water, and the potassium iodide content is usually about 0.5 to 20 parts by weight based on 100 parts by weight of water. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 °C. Further, the immersion time (dyeing time) immersed in the aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic organic dye and dyed is usually used. The content of the dichroic organic dye in the aqueous solution is usually from about 1 × 10 ^-4 to 10 parts by weight, preferably from 1 × 10 ^-3 to 1 part by weight, per 100 parts by weight of water. The aqueous dye solution may also contain an inorganic salt such as sodium sulfate as a dyeing aid. The temperature of the aqueous solution of the dichroic organic dye used for dyeing is usually about 20 to 80 °C. Further, the immersion time (dyeing time) immersed in the aqueous solution is usually about 10 to 1,800 seconds.

The boric acid treatment after dyeing by the dichroic dye can be carried out by immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. The content of boric acid in the aqueous solution containing boric acid is usually 2 to 15 parts by weight relative to 100 parts by weight of water. Right, it is preferably 5 to 12 parts by weight. When iodine is used as the dichroic dye, it is preferred that the aqueous solution containing boric acid contains potassium iodide. The content of potassium iodide in the aqueous solution containing boric acid is usually about 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The time of immersion in the aqueous solution containing boric acid is usually from about 60 to 1,200 seconds, preferably from 150 to 600 seconds, and more preferably from 200 to 400 seconds. The temperature of the aqueous solution containing boric acid is usually 50 ° C or higher, preferably 50 to 85 ° C, and more preferably 60 to 80 ° C.

The polyvinyl alcohol-based resin film after the boric acid treatment is usually subjected to a water washing treatment. The water washing treatment can be carried out, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. In the water washing treatment, the temperature of the water is usually about 5 to 40 °C. Moreover, the immersion time is usually about 1 to 120 seconds.

After washing, drying treatment was carried out to obtain a polarizing film. The drying treatment can be carried out using a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually from about 30 to 100 ° C, preferably from 50 to 80 ° C. The drying treatment time is usually about 60 to 600 seconds, preferably 120 to 600 seconds. By the drying treatment, the moisture content in the polarizing film is reduced to a practical level. The moisture content thereof is usually from about 5 to 20% by weight, preferably from 8 to 15% by weight. When the water content is less than 5% by weight, the flexibility of the polarizing film may be lost, and the film may be damaged or broken after drying. Further, when the water content exceeds 20% by weight, the thermal stability tends to be insufficient.

According to the above operation, the polarizing film 14 in which the dichroic dye is adsorbed to the polyvinyl alcohol-based resin film can be produced.

From the viewpoint of suppressing the decrease in the degree of polarization under the heat resistance test, it is also preferable to reduce the contraction force of the polarizing film itself. In order to suppress the contraction force of the polarizing film 14 to be low, the thickness of the polarizing film 14 is preferably 12 μm or less. The thickness of the polarizing film is usually 3 μm or more from the viewpoint of imparting good optical characteristics.

[Extended Optical Film 11]

In the polarizing plate used in the present invention, the stretched optical film 11 is a stretched film.

The stretched optical film 11 is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and the like. For example, a polyolefin resin such as a chain polyolefin resin (such as a polypropylene resin) or a cyclic polyolefin resin (a norbornene resin); for example, cellulose triacetate, a cellulose resin such as a cellulose ester resin such as cellulose diacetate; a polyester resin; a polycarbonate resin; a (meth)acrylic resin; a polystyrene resin; or a mixture or copolymerization thereof Things and so on. In particular, a cellulose-based resin such as cellulose ester resin such as cellulose triacetate or cellulose diacetate is preferably used in view of the fact that the present invention exhibits an effect more remarkably.

The stretched optical film 11 is preferably a film satisfying the following formula: (5) 100 nm ≦R _e (590) ≦ 180 nm, (6) 0.5 < R _th (590) / R _e (590) ≦ 0.8, (7) ) 0.85 ≦ R _e (450) / R _e (550) < 1.00, and (8) 1.00 < R _e (630) / R _e (550) ≦ 1.1. In the formula, R _e (590), R _e (450), R _e (550), and R _e (630) are respectively shown in the in-plane retardation values of the measurement wavelengths of 590 nm, 450 nm, 550 nm, and 630 nm, and R _th (590). It is expressed as a thickness direction phase difference value at a measurement wavelength of 590 nm. These in-plane phase difference values and thickness direction phase difference values were measured in an environment of a temperature of 23 ° C and a relative humidity of 55%.

The in-plane retardation value R _e and the thickness direction retardation value R _{th of} the extended optical film 11 are set to be n _x in the in-plane slow axis direction and in-plane fast axis direction (with in-plane slow axis) When the refractive index in the direction perpendicular to the direction is n _y , the refractive index in the thickness direction is n _z , and the thickness of the extended optical film 11 is d, it is defined by the following formula: R _e =(n _x -n _y ) × d R _th = [{(n _x + n _y )/2} - n _z ] × d.

A liquid crystal display in which the extended optical film 11 having the phase difference characteristics and the wavelength dispersion characteristics of the above formulas (5) to (8) is disposed on the viewing side is effective in suppressing transmission of polarized sunglasses from various directions (orientation). The angle and the polar angle) change the hue of the screen, and improve the visibility of the liquid crystal display. On the other hand, when any one of the above formulas (5) to (8) is not satisfied, the suppression of the hue change described above may be insufficient.

From the viewpoint of more effectively suppressing the hue change, R _e (590) in the formula (5) is preferably from 105 to 170 nm, and R _th (590) / R _e (590) in the formula (6) is preferably. R from 0.6 to 0.75, R _e (450) / R _e (550) in the formula (7) is preferably from 0.86 to 0.98, and R _e (630) / R _e (550) in the formula (8) is preferably 1.01. To 1.06.

The extended optical film 11 may have a polarizing film 14 a retardation film which is converted into a circularly polarized light (including a case where it is a circularly polarized light) and which emits light to the optical film 11 is formed so as to cause the function to appear, so that the absorption axis of the polarizing film and the optical film are The angle formed by the slow axis is laminated in a manner of about 45° or about 135°. When the angle formed is outside the range, the function of converting the linearly polarized light into the circularly polarized light and emitting it is not obtained, and as a result, the suppression of the above-described hue change becomes insufficient. The angle formed is preferably 35 to 55 or 125 to 145, more preferably 40 to 50 or 130 to 140.

Since the phase difference characteristics and the wavelength dispersion characteristics of the above formulas (5) to (8) are easily imparted, and the moisture permeability and the moist heat resistance of the optical layered body can be improved due to the low moisture permeability, the extended optical film system is It is preferable to contain at least one selected from the group consisting of a cyclic polyolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin, and a (meth)acrylic resin.

The chain-like polyolefin resin may, for example, be a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, and may be a copolymer containing two or more kinds of chain olefins.

The cyclic polyolefin resin is a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include a ring-opening (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a chain olefin such as a chain olefin such as ethylene or propylene. a copolymer (representatively a random copolymer); and a graft polymer modified with an unsaturated carboxylic acid or a derivative thereof; and such a hydride or the like. Among them, it is particularly preferable to use a decene-based resin which uses norbornene and A decene-based monomer such as a polycyclic norene-based monomer is used as a cyclic olefin.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, it is also possible to use such a copolymer or a part of a hydroxyl group which is modified by another substituent. Among these, cellulose triacetate (i.e., cellulose triacetate: TAC) is particularly preferred.

The polyester resin is a resin having an ester bond, and generally includes a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. The polyvalent carboxylic acid or a derivative thereof may be a divalent dicarboxylic acid or a derivative thereof, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. Wait. As the polyol, a divalent diol can be used, and examples thereof include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexane dimethanol.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polybutylene terephthalate. Ester, propylene naphthalate, dimethyl dimethyl terephthalate, cyclohexane dimethyl phthalate.

The polycarbonate resin contains a polymer in which a monomer unit is bonded via a carbonate group. The polycarbonate resin may be a resin called a modified polycarbonate such as a modified polymer skeleton, or a copolymerized polycarbonate.

The (meth)acrylic resin is a resin having a compound having a (meth)acryl fluorenyl group as a main constituent monomer. Specific examples of the (meth)acrylic resin include, for example, poly(meth)acrylate such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-( Methyl) acrylate copolymer; methyl methacrylate-acrylate-(meth)acrylic acid copolymer; methyl (meth) acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and A copolymer of a compound of an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-methyl (meth) acrylate), and the like. It is preferable to use a polymer containing a poly(meth)acrylic acid C _1-6 alkyl ester such as poly(methyl) acrylate as a main component, and more preferably a methyl methacrylate as a main component. (50 to 100% by weight, preferably 70 to 100% by weight) of a methyl methacrylate-based resin.

The stretched optical film 11 can be produced by stretching a film containing the above thermoplastic resin. The stretching treatment may be exemplified by one-axis extension and two-axis extension. The direction of extension may be, for example, the mechanical flow direction (MD) of the unstretched film, the direction perpendicular thereto (TD), and the direction in which the mechanical flow direction (MD) intersects obliquely. The two-axis extension may be a simultaneous two-axis extension while extending in two extending directions, or may be a two-axis extension extending in a predetermined direction and then extending in other directions. The stretching treatment can be performed, for example, by using two or more pairs of nip rolls that increase the number of revolutions on the outlet side and extending in the long direction (mechanical flow direction: MD), or not extending Both ends of the film are clamped by a chuck and extended in a direction (TD) perpendicular to the direction of mechanical flow. At this time, by adjusting the thickness of the film or adjusting the stretching ratio, the phase difference value and the wavelength dispersion can be adjusted within the range of the above formulas (5) to (6). Further, by adding a wavelength dispersion adjusting agent to the resin, the wavelength dispersion value can be adjusted within the range of the above formulas (7) to (8).

The thickness of the stretched optical film 11 is not particularly limited as long as it satisfies the above formulas (5) to (8), but is preferably 90 μm or less, and more preferably 60 μm or less from the viewpoint of film formation of the polarizing plate. From the viewpoint of handling, it is preferably 5 μm or more, and more preferably 10 μm or more.

The stretched optical film 11 may contain one or more additives such as a smoothing agent, a plasticizer, a dispersing agent, a heat stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent, and an antioxidant.

Moreover, in order to impart desired surface optical characteristics or other characteristics, a coating layer (surface treatment layer 20) may be provided on the outer surface of the optical film 11. Specific examples of the coating layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer. The method of forming the coating layer is not particularly limited, and a known method can be used.

[First protective film 13]

The first protective film 13 is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and the like. From the viewpoint of easy availability, the first protective film 13 is preferably at least one selected from the group consisting of a cellulose resin, a polyolefin resin, and an acrylic resin. Here, the polyolefin resin includes a chain polyolefin resin and a cyclic polyolefin resin. In the present specification, the transparency means a film having a monomer transmittance of 80% or more in the visible light region.

The cellulose resin, the polyolefin resin, or the acrylic resin can be the same as those used for the optical film.

The method of forming a film by the above resin may be appropriately selected depending on each resin, and for example, a solvent casting method or melt extrusion may be employed. Acting, etc. Among them, the polyolefin resin and the acrylic resin are preferably melt-extruded from the viewpoint of productivity. On the other hand, in general, a cellulose resin is formed by a solvent casting method.

The first protective film 13 is obtained by using a dimensional change ratio D1 in a direction of 45° with respect to the absorption axis of the polarizing film after standing for 100 hours in an environment of 85° C., and 135 with respect to the absorption axis of the polarizing film. The dimensional change rate D2 in the direction of ° is those satisfying the following formulas (1) and (2). In the present specification, the direction formed by the angle of the absorption axis of the polarizing film of 45° and the angle formed by the absorption axis of the polarizing film is 135°, as shown in Fig. 2, the main surface of the polarizing plate The inner angles indicate a direction 21 at an angle of 45 with respect to the absorption axis 30 of the polarizing film, and a direction 22 at an angle of 135 with respect to the absorption axis 30 of the polarizing film. Moreover, when the polarizing film 14 is seen from the extended optical film 11, the angle which rotates counterclockwise is positive. |D1|≧|D2|, 1≦|D1|/|D2|≦2 (1) |D1|<|D2|,1<|D2|/|D1|≦2 (2)

When the film satisfying the above formula has a small anisotropy of heat shrinkage and thermal expansion during the heat resistance test, it is possible to suppress the shift of the absorption axis of the polarizing film 14 due to dimensional change due to heat of the stretched optical film. The film satisfying the above formulas (1) and (2) can be obtained by substantially not stretching when the film is produced. In the present specification, the stretching ratio in either direction of the film surface is substantially 1.1 times or less, preferably 1.05 times or less. Or, from another point of view, it means that the phase difference in the plane of the film is 20 nm or less at a wavelength of 590 nm.

D1 and D2 in the above formulas (1) and (2) can be based on the following The method is determined. First, the film was cut to have a size of 100 mm in a direction of 45° with respect to the absorption axis of the polarizing film, and a size of 100 mm in a direction of 135°. The cut film was allowed to stand in an environment of a temperature of 23 ° C and a humidity of 55% for one day, and the size (L0 (45)) in the direction of 45° with respect to the absorption axis of the polarizing film and the polarizing film were measured. The axis is absorbed in the direction of 135° (L0 (135)). Next, the size (L1 (45)) in the direction of 45° from the absorption axis of the polarizing film and the direction in the direction of 135° from the absorption axis of the polarizing film were measured after standing for 100 hours in an environment of 85 ° C ( L1 (135)). Based on the results, the dimensional change rates D1 (%) and D2 (%) can be obtained from the equations (3) and (4). Dimensional change rate D1=[(L0(45)-L1(45))/L0(45)]×100 (3) Dimensional change rate D2=[(L0(135)-L1(135))/L0(135) ]×100 (4)

By using the first protective film satisfying the above formulas (1) and (2), the present invention can appropriately suppress the polarized light of the polarizing plate even when the stretched optical film is a film having a large dimensional change ratio satisfying the following formula. Degree is reduced. Further, in the following formulas (1) and (2), the left side of each formula may be 2.5 or more, and may be 3.0 or more. |D1|≧|D2|, 2≦|D1|/|D2| (1') |D1|<|D2|, 2<|D2|/|D1| (2')

Further, in the above formulae (1') and (2'), the definitions of D1 and D2 are the same as those in the above formulas (1) and (2).

[Second protective film 15]

The second protective film 15 is preferably made of a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, and the like. In the case of the second protective film 15, it is easy to adjust the retardation value and it is easy to obtain. From the viewpoint, it is preferable to contain a cellulose resin, a polyolefin resin, or an acrylic resin. Here, the polyolefin resin includes a chain polyolefin resin and a cyclic polyolefin resin.

The cellulose resin, the polyolefin resin, or the acrylic resin can be the same as those of the first protective film.

The method of forming a film by the above resin may be appropriately selected depending on each resin, and for example, a solvent casting method, a melt extrusion method, or the like as described above may be employed. Among them, the polyolefin resin and the acrylic resin are preferably melt-extruded from the viewpoint of productivity. On the other hand, in general, a cellulose resin is formed by a solvent casting method.

When the liquid crystal cell is in the IPS (In-Plane Switching) mode, the transparent protective film has a phase difference R _th in the thickness direction of -10 in order not to impair the original wide viewing angle characteristic of the IPS mode liquid crystal cell. A range of up to 10 nm is preferred.

The method of adjusting the phase difference R _th in the thickness direction of the transparent protective film in the range of -10 to 10 nm is a method of reducing the distortion remaining in the in-plane and thickness directions as much as possible in the production of the film. In the solvent casting method, for example, a method in which residual shrinkage distortion in the in-plane and thickness directions generated when the cast resin solution is dried is moderated by heat treatment can be employed. On the other hand, in the above melt extrusion method, in order to prevent the resin film from being stretched between extrusion and cooling from the die, it is possible to minimize the distance from the die to the cooling cylinder and to prevent the film from being stretched. A method of controlling the amount of extrusion and the rotation speed of the cooling cylinder, and the like. Further, similarly to the solvent casting method, a method of alleviating the distortion remaining in the obtained film by heat treatment may be employed.

[Adhesion of polarizing film and protective film]

The bonding of the polarizing film to the first protective film and the bonding of the polarizing film and the second protective film may be carried out by bonding with an adhesive or an adhesive, preferably by bonding with an adhesive. In the present specification, the first protective film and the second protective film are collectively referred to simply as a protective film.

The adhesive layer to which the polarizing film and the protective film are bonded may have a thickness of about 0.01 to 30 μm, preferably 0.01 to 10 μm, and more preferably 0.05 to 5 μm. When the thickness of the subsequent layer is in this range, floating and peeling do not occur between the protective film and the polarizing film, and an adhesive force which is practically free from problems can be obtained. The adhesive layer to which the polarizing film and the protective film are bonded may have a thickness of about 5 to 50 μm, preferably 5 to 30 μm, and more preferably 10 to 25 μm.

When the polarizing film and the protective film are to be bonded together, it is also useful if the polarizing film or the protective film is previously subjected to saponification treatment, corona treatment, plasma treatment, or the like.

The adhesive can be suitably used for a user who laminates an optical film and a protective film described later.

In the formation of the subsequent layer, an appropriate adhesive can be suitably used depending on the type and purpose of the object to be used, and an anchor coating agent can also be used as needed. Examples of the subsequent agent include a solvent-based adhesive, an emulsion-type adhesive, a pressure-sensitive adhesive, a rewet adhesive, a polycondensation adhesive, a solventless adhesive, a film adhesive, and a hot melt. Type of adhesive, etc.

One of the preferred adhesives is a water-based adhesive, and even if the adhesive component is dissolved or dispersed in water. An example of a component which can be dissolved in water is a polyvinyl alcohol-based resin. Further, examples of the component which can be dispersed in water are urethane-based resins having a hydrophilic group. The aqueous binder can be prepared by mixing such an adhesive component with water as needed, in addition to an additional additive. In the case of a commercially available polyvinyl alcohol-based resin which can be used as a water-based adhesive, there is a "KL-318" which is a carboxylic acid group-modified polyvinyl alcohol sold by Kuraray Co., Ltd., and the like.

The aqueous binder may contain a crosslinking agent as desired. Examples of the crosslinking agent include an amine compound, an aldehyde compound, a methylol compound, a water-soluble epoxy resin, an isocyanate compound, a polyvalent metal salt, and the like. When a polyvinyl alcohol-based resin is used as the adhesive component, an aldehyde compound such as glyoxal, a methylol compound such as methylol melamine, a water-soluble epoxy resin or the like is preferably used as the crosslinking agent.

Here, the water-soluble epoxy resin may be, for example, a polydecylamine epoxy resin obtained by reacting a polyamine polyamine with epichlorohydrin, such as a diamethylenetriamine, a triple extension. A reaction product of a polyalkylene polyamine such as ethylene tetraamine and a dicarboxylic acid such as adipic acid. In the case of a commercial product of a water-soluble epoxy resin, "Sumirez Resin (registered trademark) 650 (30)" sold by Takoka Chemical Industry Co., Ltd., and the like are available.

A water-based adhesive is applied to the surface of the polarizing film and/or the protective film bonded to the polarizing film, and the two are bonded together, followed by drying treatment, whereby a polarizing plate can be obtained. Before the next step, if the protective film is applied first It is also effective if the saponification treatment, the corona discharge treatment, the plasma treatment, or the primer treatment is easily followed to improve the wettability. The drying temperature may be, for example, about 50 to 100 °C. From the viewpoint of further improving the adhesion, it is preferred to be cooked at a temperature slightly higher than room temperature (for example, a temperature of about 30 to 50 ° C) for about 1 to 10 days after the drying treatment.

Another preferred adhesive agent is a curable adhesive composition containing an epoxy compound which is cured by irradiation with an active energy ray or heating. Here, the curable epoxy compound is one having at least two epoxy groups in the molecule. In this case, the polarizing film and the protective film may be subsequently cured by irradiating the coating layer of the adhesive composition with an active energy ray or imparting heat to harden the curable epoxy compound contained in the adhesive. . The hardening of the epoxy compound is generally carried out by cationic polymerization of an epoxy compound. Further, from the viewpoint of productivity, the curing is preferably carried out by irradiation with active energy rays.

The epoxy compound contained in the curable adhesive composition preferably has no aromatic ring in the molecule from the viewpoints of weather resistance, refractive index, cationic polymerizability and the like. The epoxy compound containing no aromatic ring in the molecule may, for example, be a hydrogenated epoxy compound, an alicyclic epoxy compound or an aliphatic epoxy compound. The epoxy compound which can be suitably used for the composition of the curable adhesive is described in detail in, for example, Japanese Laid-Open Patent Publication No. 2004-245925, which is also hereby expressly described.

The hydrogenated epoxy compound may be obtained by glycidyl etherification of a nuclear hydrogenated polyhydroxy compound by using an aromatic polyhydroxy compound belonging to a raw material of an aromatic epoxy compound. It is obtained by selectively performing a nuclear hydrogenation reaction in the presence of a catalyst and under pressure. Examples of the aromatic polyhydroxy compound which is a raw material of the aromatic epoxy compound include bisphenols such as bisphenol A, bisphenol F and bisphenol S; for example, phenol novolac resin, cresol novolac resin And a novolac type resin such as a hydroxybenzaldehyde phenol novolak resin; a polyfunctional compound such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone or polyvinylphenol. The glycidyl etherification can be carried out by subjecting such an aromatic polyhydroxy compound to a nuclear hydrogenation reaction and reacting the obtained nuclear hydrogenated polyhydroxy compound with epichlorohydrin. Suitable hydrogenated epoxy compounds include, for example, the glycidyl ether of hydrogenated bisphenol A.

The alicyclic epoxy compound is a compound having at least one epoxy group bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means the bridged oxygen atom -O- in the structure represented by the following formula, wherein m is an integer of 2 to 5.

A compound obtained by combining a group in which one or a plurality of hydrogen atoms in the formula (CH ₂ ) _m is removed from another chemical structure may be an alicyclic epoxy compound. Further, one or a plurality of hydrogen atoms in the (CH ₂ ) _m forming the alicyclic ring may be suitably substituted with a linear alkyl group such as a methyl group or an ethyl group. Among the alicyclic epoxy compounds, an epoxy compound having an oxabicyclohexane ring (m=3 in the above formula) and an oxabicycloheptane ring (m=4 in the above formula) is excellent in performance. The adhesion is preferred. Specific examples of the alicyclic epoxy compound are disclosed below. Here, the compound names are listed first, and the corresponding chemical formulas are respectively indicated, and the same symbols are used for the compound name and the chemical formula corresponding to the chemical name.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylic acid, B: 3,4-epoxy-6-methylcyclohexanecarboxylic acid 3,4-epoxy -6-methylcyclohexylmethyl ester, C: exoethyl bis(3,4-epoxycyclohexanecarboxylate), D: adipic acid bis(3,4-epoxycyclohexylmethyl) Ester, E: bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, F: diethylene glycol bis(3,4-epoxycyclohexylmethyl ether) , G: ethylene glycol bis(3,4-epoxycyclohexylmethyl ether), H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxaspiro [5.2.2.5.2.2] Behenane, I: 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5]undecane , J: 4-vinylcyclohexene dioxide, K: limonene dioxide, L: bis(2,3-epoxycyclopentyl) ether, M: dioxide Dicyclopentadiene and the like.

The aliphatic epoxy compound may be a polyglycidyl ether of an aliphatic polyol or an alkylene oxide adduct thereof. More specifically, for example, diglycidyl ether of propylene glycol; 1,4-butanediol Diglycidyl ether; diglycidyl ether of 1,6-hexanediol; triglycidyl ether of glycerol; triglycidyl ether of trimethylolpropane; for fats such as ethylene glycol, propylene glycol and glycerol The polyhydric alcohol is added to an alkylene oxide (for example, ethylene oxide or propylene oxide) to obtain a polyglycidyl ether of a polyether polyol (for example, a diglycidyl ether of polyethylene glycol).

In the composition of the curable adhesive, the epoxy compound may be used alone or in combination of two or more. Among them, the epoxy compound preferably includes an alicyclic epoxy compound having at least one epoxy group bonded to the alicyclic ring in the molecule.

The epoxy compound which can be used in the composition of the curable adhesive usually has an epoxy equivalent in the range of 30 to 3,000 g/eq, and the epoxy equivalent is preferably in the range of 50 to 1,500 g/eq. When an epoxy compound having an epoxy equivalent of less than 30 g/equivalent is used, the flexibility of the polarized plate after hardening may be lowered, and then the strength may be lowered. On the other hand, in order to use a compound having an epoxy equivalent of more than 3,000 g/eq, the compatibility with other components contained in the adhesive composition may be lowered.

From the viewpoint of reactivity, it is preferred to use cationic polymerization as a hardening reaction of an epoxy compound. Therefore, in the curable adhesive composition containing an epoxy compound, a cationic polymerization initiator is preferably used. The cationic polymerization initiator starts a polymerization reaction by irradiating an active energy ray such as visible light, ultraviolet rays, X-rays, and electron rays or heating to generate a cationic species or a Lewis acid. From the viewpoint of workability, the cationic polymerization initiator is preferably imparted with latent properties. Hereinafter, a cationic species or pathway will be produced by irradiating an active energy ray. A cationic polymerization initiator which starts the polymerization of an epoxy group and is called a "photocationic polymerization initiator". In addition, a cationic species or a Lewis acid is generated by heat and the epoxy group starts to polymerize. The cationic polymerization initiator of the reaction is referred to as "thermal cationic polymerization initiator".

By using a photocationic polymerization initiator and irradiating an active energy ray to perform hardening of the adhesive composition, the curing can be performed under normal temperature and normal humidity, and the heat resistance or expansion of the polarizing film can be less considered. It is advantageous because the skew is caused and the protective film and the polarizing film are well adhered. Further, since the photocationic polymerization initiator exhibits a catalytic action by light, it is excellent in storage stability and workability even when it is mixed with an epoxy compound.

The photocationic polymerization initiator may, for example, be an aromatic diazonium salt; an onium salt such as an aromatic onium salt or an aromatic onium salt; an iron-propene complex (allene) complex. The compounding amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and preferably 15 parts by weight or less based on 100 parts by weight of the epoxy compound.

When the amount of the photocationic polymerization initiator is less than 0.5 part by weight based on 100 parts by weight of the epoxy compound, the hardening may be insufficient, and the mechanical strength and the subsequent strength of the cured product tend to be lowered.

On the other hand, when the amount of the photocationic polymerization initiator is more than 20 parts by weight based on 100 parts by weight of the epoxy compound, the ionic substance in the cured product increases, and the hygroscopicity of the cured product becomes high. May reduce durability.

When a photocationic polymerization initiator is used, the hardenability is followed The composition of the agent may further contain a photosensitizer as desired. By using a photosensitizer, the reactivity of cationic polymerization can be improved, and the mechanical strength and the subsequent strength of the cured product can be improved. Examples of the photosensitizer include a carbonyl compound, an organic sulfide, a persulfide compound, a redox compound, an azo compound, a diazo compound, a halogen compound, and a photoreductive dye. When the photosensitizer is formulated, the amount thereof is preferably in the range of 0.1 to 20 parts by weight based on 100 parts by weight of the curable adhesive composition. Further, in order to increase the curing speed, a sensitizer such as a naphthoquinone derivative may also be used.

On the other hand, the thermal cationic polymerization initiator may, for example, be a benzyl sulfonium salt, a thiophenium salt, a thiolanium salt, a benzylammonium salt, a pyridinium salt or a phosphonium salt ( Hydrazinium salt), carboxylic acid ester, sulfonate, amino ruthenium, and the like.

The curable adhesive composition containing an epoxy compound is preferably cured by photocationic polymerization as described above, but the above thermal cationic polymerization initiator may be present and hardened by thermal cationic polymerization, or may be used in combination. Photocationic polymerization and thermal cationic polymerization. In the case of photocationic polymerization and thermal cationic polymerization, it is preferred to contain both a photocationic polymerization initiator and a thermal cationic polymerization initiator in the curable adhesive composition.

Further, the curable adhesive composition may further contain a compound which promotes cationic polymerization such as an oxetane compound and a polyol compound. The oxetane compound is a compound having a 4-membered cyclic ether in the molecule. When the oxetane compound is blended, the amount thereof is usually from 5 to 95% by weight, preferably from 5 to 50% by weight, based on the composition of the curable adhesive. Moreover, the polyol compound may be ethylene glycol or hexamethylene glycol, polyethylene glycol An alkylene glycol such as a diol or an oligomer thereof, a polyester polyol, a polycaprolactone polyol, a polycarbonate polyol or the like. When the polyol compound is blended, the amount is usually 50% by weight or less, preferably 30% by weight or less, based on the curable adhesive composition.

In addition, the curable adhesive composition may contain other additives such as an ion trapping agent, an antioxidant, a chain transfer agent, a sensitizer, a tackifier, and a thermoplastic resin without impairing its adhesion. , fillers, flow regulators, plasticizers, defoamers, etc. The ion trapping agent may, for example, be an inorganic compound containing a powdery lanthanoid, lanthanoid, magnesium, aluminum, calcium, titanium, or the like, and examples of the antioxidant include hindered phenol antioxidants. Wait.

After applying the curable adhesive composition containing the epoxy compound to the adhesion surface of the polarizing film or the protective film, or the adhesion surface of the both, bonding with the surface coated with the adhesive, and irradiating the active energy ray The uncured adhesive layer is hardened by heating, whereby the polarizing film and the protective film can be bonded. The coating method of the subsequent agent can employ various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, a gravure coater, and the like.

The curable adhesive composition can be basically used as a solventless adhesive which does not substantially contain a solvent, but various coating methods have respective optimum viscosity ranges, so that a solvent can be contained for adjusting the viscosity. . The solvent is preferably an organic solvent which does not reduce the optical properties of the polarizing film and can dissolve various components including an epoxy compound. For example, a hydrocarbon represented by toluene or an ester represented by ethyl acetate can be used. .

When the adhesive composition is cured by irradiation with an active energy ray, the above-described various types of active energy ray can be used. However, from the viewpoint of easy handling and easy adjustment of the amount of irradiation light, ultraviolet rays are preferably used. The irradiation intensity and the irradiation amount of the active energy ray (for example, ultraviolet ray) are not affected by various optical properties such as the degree of polarization of the polarizing film and various optical properties including the transparency and phase difference characteristics of the protective film. It is appropriately determined in such a manner as to maintain proper productivity.

When the curing of the adhesive composition is carried out by heat, it can be heated according to a generally known method. The thermal cationic polymerization initiator which is formulated in the curable adhesive composition is usually heated at a temperature above the temperature at which the cationic species and the Lewis acid are generated, and the specific heating temperature is, for example, about 50 to 200 °C.

[Lamination of the first protective film 13 and the optical film 11]

The laminate of the first protective film 13 and the optical film 11 can be the same as the adhesive used for bonding the polarizing film and the protective film. In another embodiment, an adhesive is preferably used for laminating the first protective film 13 and the optical film 11.

[Adhesive layer 12]

The adhesive layer 12 used for laminating the first protective film 13 and the optical film 11 is preferably excellent in optical transparency, suitable in wettability, and excellent in adhesion properties including aggregation property and adhesion property. It is superior to durability and the like. Specifically, the adhesive forming the adhesive layer 12 is preferably an adhesive (acrylic adhesive) containing an acrylic resin.

The acrylic resin contained in the acrylic adhesive is, for example, butyl acrylate, ethyl acrylate, isooctyl acrylate, and acrylic acid. A resin in which an alkyl acrylate such as 2-ethylhexyl ester is a main monomer. A polar monomer is usually copolymerized in the acrylic resin. A polar single system having a polymerizable unsaturated bond and a polar functional group, wherein the polymerizable unsaturated bond is generally derived from a (meth) acrylonitrile group, and the polar functional group may be a carboxyl group, a hydroxyl group or a guanamine group. , amine group, epoxy group, and the like. Specific examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylamide, (A) Base) 2-N,N-dimethylaminoethyl acrylate, glycidyl (meth)acrylate, and the like.

Further, in the acrylic pressure-sensitive adhesive, a crosslinking agent is usually blended together with an acrylic resin.

Representative examples of the crosslinking agent include an isocyanate compound having at least two isocyanate groups (-NCO) in the molecule.

Various additives can be further formulated in the adhesive. Suitable additives include a decane coupling agent, an antistatic agent, and the like. The decane coupling agent is effective for increasing the adhesion to the glass. Antistatic agents are effective in reducing or preventing the generation of static electricity.

The adhesive layer 12 can be formed by dissolving an adhesive composition in which an adhesive component is dissolved in an organic solvent, and applying the adhesive composition directly to any subsequent bonding surface (polarized light) a method of removing a solvent by drying a film or a protective film; or coating the above-mentioned adhesive composition on a release-treated surface of a substrate film containing a resin film subjected to release treatment, drying and removing the solvent to form an adhesive A layer of the adhesive layer, and the adhesive layer is attached to any of the bonding surfaces (polarizing film or protective film), and the adhesive is transferred. When the adhesive layer 12 is formed by the direct coating method of the former, conventionally, A resin film (also referred to as a separator) subjected to release treatment is attached to the surface thereof to temporarily protect the surface of the adhesive layer until use. From the viewpoint of the handleability of the adhesive composition of the organic solvent solution, etc., the latter transfer method is often employed. In this case, the release-treated base film used in the formation of the first adhesive layer is It can be directly used as a separator after being attached to a polarizing plate, and is also suitable for this feature.

It is also useful to perform corona treatment, plasma treatment, etc. on the surface of the polarizing film to be bonded, the surface of the protective film, and the surface of the adhesive before the lamination by the adhesive and the adhesive.

[Adhesive layer 16]

The adhesive layer 16 can be used as an adhesive layer for bonding the polarizing plate 10 to the liquid crystal cell.

The adhesive layer 16 formed on the side of the polarizing film 14 which is away from the first protective film is preferably excellent in optical transparency, suitable in wettability, and excellent in adhesion properties including aggregation property and adhesion property. In order to use it even better in durability and the like. Specifically, it is preferable to use an adhesive (acrylic adhesive) containing an acrylic resin as the adhesive for forming the adhesive layer. Specifically, the same as the aforementioned adhesive 12 can be used. The adhesive layer 16 and the adhesive layer 12 may be formed of the same adhesive or may be formed of a different adhesive.

The adhesive layer 16 may contain various additives similarly to the adhesive layer 12. Preferably, the adhesive layer 16 contains an antistatic agent. In general, when the polarizing plate is attached to the liquid crystal cell via the adhesive layer, the surface protective film (separator) that has been temporarily covered with the adhesive layer to be temporarily protected is used. After being peeled off and then bonded to the liquid crystal cell, static electricity is generated when the surface protective film is peeled off, and the liquid crystal in the liquid crystal cell is poorly oriented. This phenomenon may cause a display failure of the liquid crystal display device. For the means for reducing or preventing the generation of such static electricity, it is effective to formulate an antistatic agent in the adhesive.

When the second protective film 15 and the adhesive layer 16 are bonded together, it is also useful to perform corona treatment, plasma treatment, or the like on the surface where the second protective film 15 and the adhesive layer 16 are bonded to each other.

[Method of Manufacturing Polarizing Plate]

The method for producing the polarizing plate of the present invention is not particularly limited. For example, a polarizing plate in which the first protective film 13, the polarizing film 14, and the second protective film 15 are laminated, and the optical film 11 and the adhesive can be prepared in advance. An optical film with an adhesive layer laminated on the layer 12 is bonded to the adhesive layer 12 of the optical film to which the adhesive is attached, and is roll-to-rolled to obtain polarized light. Board 10. By further forming the adhesive layer 16 on the second protective film 15, the polarizing plate can be bonded to the liquid crystal cell via the adhesive layer 16.

[Liquid Crystal Unit]

The liquid crystal cell has two unit substrates and a liquid crystal layer sandwiched between the two substrates. The unit substrate is generally made of glass, but may be a plastic substrate. Further, the liquid crystal cell itself used in the liquid crystal panel of the present invention can be composed of various substances used in the field.

[LCD panel]

The liquid crystal panel can be produced by bonding the polarizing plate 10 to the liquid crystal cell via the adhesive layer 16. The polarizing plate of the present invention is only attached to the liquid crystal cell At least one of the back side and the viewing side may be used. The polarizing plate of the present invention is preferably attached to the liquid crystal cell in such a manner that the polarizing plate of the present invention is disposed on the viewing side of the liquid crystal display device.

[Examples]

The following series are shown to further illustrate the invention, but the invention is not limited by the examples. In the examples, the parts and % of the content or the amount used are indicated on a weight basis unless otherwise specified. Further, the measurement of each physical property in the following examples was carried out by the following method.

(1) Determination of thickness:

It was measured using a digital micrometer "MH-15M" manufactured by Nikon Co., Ltd.

(2) Determination of in-plane retardation and thickness direction delay:

Using the phase difference meter "KOBRA (registered trademark) - WPR" manufactured by Oji Scientific Instruments Co., Ltd. as a parallel nicols rotation method, the in-plane retardation at a predetermined wavelength at a temperature of 23 ° C was measured. And the thickness direction is delayed.

(3) Determination of the degree of polarization and the transmittance of the monomer of the polarizing plate:

It was measured using a spectrophotometer ("V7100" manufactured by JASCO Corporation, 2 degree field of view; C light source) with an integrating sphere.

(4) Method for measuring dimensional change rate of film

The dimensional change rate D1 in the direction of 45° with respect to the absorption axis of the polarizing film after the film was allowed to stand in an environment of 85° C. for 100 hours, and the dimension in the direction of 135° with respect to the absorption axis of the polarizing film were measured. The method of the rate of change D2 is as follows. First, the film is cut to make it absorb relative to the polarizing film. It is 100 mm in the direction of 45° and 100 mm in the direction of 135°. The cut film was allowed to stand in an environment of a temperature of 23 ° C and a humidity of 55% for one day, and the size (L0 (45)) in the direction of 45° with respect to the absorption axis of the polarizing film and absorption with respect to the polarizing film were measured. The axis is in the direction of 135° (L0 (135)). Next, the size (L1 (45)) in the direction of 45° with respect to the absorption axis of the polarizing film after standing for 100 hours in an environment of 85 ° C was measured, and it was 135° with respect to the absorption axis of the polarizing film. Direction size (L1 (135)). Based on the results, the dimensional change rates D1 (%) and D2 (%) were obtained from the equations (3) and (4). Dimensional change rate D1=[(L0(45)-L1(45))/L0(45)]×100 (3) Dimensional change rate D2=[(L0(135)-L1(135))/L0(135) ]×100 (4)

[Manufacturing Example 1] Production of polarizing film

A polyvinyl alcohol film having a thickness of 30 μm (average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more) was stretched by a dry stretching to about 4 times, and then kept at a tight state, at 40 ° C of pure water. After immersing for 40 seconds, the mixture was immersed in an aqueous solution of iodine/potassium iodide/water in a weight ratio of 0.052/5.7/100 at 28 ° C for 30 seconds to carry out a dyeing treatment. Thereafter, it was immersed in an aqueous solution of potassium iodide/boric acid/water in a weight ratio of 11.0/6.2/100 at 70 ° C for 120 seconds. Then, after washing with pure water at 8 ° C for 15 seconds, it was dried at 60 ° C for 50 seconds while maintaining a tension of 300 N, and then dried at 75 ° C for 20 seconds to obtain a thickness of 12 μm of iodine adsorbed on the polyvinyl alcohol film. Absorptive polarizer.

[Production Example 2] Production of a water-based adhesive

3 parts by weight of a carboxyl group-modified polyvinyl alcohol (trade name "KL-318" obtained by Kuraray Co., Ltd.) was dissolved in 100 parts by weight of water. To the aqueous solution, a polyamine-based epoxy-based additive which is a water-soluble epoxy resin (Sumirez Resin (registered trademark) 650 (30), which is obtained from Takooka Chemical Industry Co., Ltd.), and a solid content concentration of 30% by weight is added. The aqueous solution was 1.5 parts by weight to prepare a water-based adhesive.

[adhesive]

Prepare the following adhesives A and B.

Adhesive A: a sheet-like adhesive having a thickness of 25 μm ["P-3132" manufactured by Lintec Co., Ltd.]

Adhesive B: a sheet-like adhesive having a thickness of 5 μm [NCF # L2" manufactured by Lintec Co., Ltd.).

[Transparent protective film A to E]

Prepare the following five protective films.

Protective film A: cellulose triacetate film manufactured by Konicaminolta Co., Ltd.; KC2CT (thickness 20 μm, in-plane retardation value at wavelength 590 nm = 1.2 nm, phase difference in thickness direction at wavelength 590 nm = 1.3 nm)

Protective film B: a cyclic polyolefin resin film manufactured by Zeon Co., Ltd.; ZF14-023 (thickness 23 μm, in-plane retardation value at wavelength 590 nm = 0.5 nm, phase difference in thickness direction at wavelength 590 nm = 4.3 nm )

Protective film C: cellulose triacetate film manufactured by Konicaminolta Co., Ltd.; KU2UAW (thickness 25 μm, dimensional change rate D1 = 0.11%, dimensional change rate D2 = 0.20%, |D1|/|D2|=1.05)

Protective film D: cellulose triacetate film manufactured by Konicaminolta Co., Ltd.; KU2UAW was laterally stretched into a film of 1.05 times by a tenter type stretching machine (thickness 24 μm, dimensional change rate D1 = 0.11%, dimensional change rate) D2=0.38%, |D2|/|D1|=1.81)

Protective film E: cellulose triacetate film manufactured by Konicaminolta Co., Ltd.; KU2UAW was laterally extended to a 1.15 times film by a tenter type stretching machine (thickness 22 μm, dimensional change rate D1 = 0.11%, dimensional change rate D2 = 0.47) %, |D2|/|D1|=2.24)

[Optical film]

Optical film: Prepared cellulose acetate film made by Konicaminolta Co., Ltd.; KC4UGR-HC (thickness 44 μm, in-plane retardation value at wavelength 590 nm = 106 nm, phase difference in thickness direction at wavelength 590 nm = 75 nm, R _th (590 ) /R _e (590)=0.71, R _e (450)/R _e (550)=0.96, R _e (630)/R _e (550)=1.02, dimensional change rate D1=0.08%, dimensional change rate D2 =0.26%, |D2|/|D1|=3.25).

(Example)

[Example 1]

The saponification treatment is performed on the protective film A, the protective film C, and the optical film. The protective film A, the polarizing film, and the protective film C were sequentially adhered with a water-based adhesive to obtain a polarizing plate. Next, an adhesive film of an adhesive film is obtained by adhering the adhesive agent B to one area of the optical film. The polarizing plate was obtained by bonding the surface of the protective film C of the obtained polarizing plate to the adhesive surface of the optical film to which the adhesive was applied so that the absorption axis of the polarizing plate and the slow axis of the optical film were 135°. Further, an adhesive A was laminated on the protective film A side of the obtained polarizing plate to obtain a polarizing plate with an adhesive. The polarizing plate has a degree of polarization of 99.997%.

The polarizing plate was cut out to a size of 40 mm square, and attached to EAGLE XG manufactured by Corning Co., Ltd. to prepare a sample for evaluation of heat resistance test. The sample prepared in this manner was placed in an oven at 85 ° C for 750 hours. The degree of polarization after the heat resistance test was 99.983%.

[Embodiment 2]

Corona treatment is performed on one side of the protective film B, and saponification treatment is performed on the protective film C and the optical film. The corona-treated surface of the protective film B, the polarizing film, and the protective film C were sequentially adhered with a water-based adhesive to obtain a polarizing plate. Next, an adhesive film of an adhesive film is obtained by adhering the adhesive agent B to one area of the optical film. The protective film C surface side of the obtained polarizing plate and the adhesive surface of the optical film with an adhesive agent were bonded together so that the absorption axis of the polarizing plate and the slow axis of the optical film were 135 degrees, and the polarizing plate was obtained. Further, an adhesive A was laminated on the protective film B side of the obtained polarizing plate to obtain a polarizing plate with an adhesive. The polarizing plate has a degree of polarization of 99.997%.

The polarizing plate was cut out to a size of 40 mm square, and attached to EAGLE XG manufactured by Corning Co., Ltd. to prepare a sample for heat resistance evaluation. The sample prepared in this manner was placed in an oven at 85 ° C for 750 hours. The degree of polarization after the heat resistance test was 99.983%.

[Example 3]

Corona treatment is performed on one side of the protective film B, and saponification treatment is performed on the protective film D and the optical film. The corona-treated surface of the protective film B, the polarizing film, and the protective film D were sequentially adhered with a water-based adhesive to obtain a polarizing plate. At this time, the absorption axis of the polarizing film and the extending direction of the protective film D were 135°. Next, an adhesive film of an adhesive film is obtained by adhering the adhesive agent B to one area of the optical film. The protective film D side of the obtained polarizing plate is attached to the adhesive film so that the absorption axis of the polarizing plate and the slow axis of the optical film are 135°. The adhesive surface of the optical film of the agent is attached to obtain a polarizing plate. Further, an adhesive A was laminated on the protective film B side of the obtained polarizing plate to obtain a polarizing plate with an adhesive. The polarizing plate has a degree of polarization of 99.996%.

The polarizing plate was cut out to a size of 40 mm square, and attached to EAGLE XG manufactured by Corning Co., Ltd. to prepare a sample for heat resistance evaluation. The sample prepared in this manner was placed in an oven at 85 ° C for 750 hours. The degree of polarization after the heat resistance test was 99.981%.

[Comparative Example 1]

Corona treatment was performed on one side of the protective film B, and saponification treatment was performed on the optical film. The corona-treated surface, the polarizing film, and the optical film of the protective film B were sequentially passed through with a water-based adhesive to obtain a polarizing plate. The absorption axis of the obtained polarizing plate was made 135 ° to the slow axis of the optical film. Further, an adhesive A was laminated on the protective film B side of the obtained polarizing plate to obtain a polarizing plate with an adhesive. The polarizing plate has a degree of polarization of 99.992%.

The polarizing plate was cut out to a size of 40 mm square, and attached to EAGLE XG manufactured by Corning Co., Ltd. to prepare a sample for heat resistance evaluation. The sample prepared in this manner was placed in an oven at 85 ° C for 750 hours. The degree of polarization after the heat resistance test was 99.963%.

[Comparative Example 2]

Corona treatment was performed on one side of the protective film B, and saponification treatment was performed on the protective film E and the optical film. The corona-treated surface of the protective film B, the polarizing film, and the protective film E were sequentially adhered with a water-based adhesive to obtain a polarizing plate. At this time, the absorption axis of the polarizing film and the extending direction of the protective film E were 135°. Secondly, in one area of the optical film, the adhesive B is obtained. An optical film with an adhesive. The surface of the protective film E of the obtained polarizing plate and the adhesive surface of the optical film with an adhesive were bonded together so that the absorption axis of the polarizing plate and the slow axis of the optical film were 135 degrees, and the polarizing plate was obtained. Further, an adhesive A was laminated on the protective film B side of the obtained polarizing plate to obtain a polarizing plate with an adhesive. The polarizing plate has a degree of polarization of 99.994%.

The polarizing plate was cut out to a size of 40 mm square, and attached to EAGLE XG manufactured by Corning Co., Ltd. to prepare a sample for heat resistance evaluation. The sample prepared in this manner was placed in an oven at 85 ° C for 750 hours. The degree of polarization after the heat resistance test was 99.975%.

The above results are summarized in Table 1.

(industrial availability)

According to the present invention, it is possible to provide a polarizing plate which suppresses a decrease in the degree of polarization caused by a shift in the absorption axis of the polarizing film due to a dimensional change of the stretched optical film when the heat resistance test is performed.

10‧‧‧Polar plate

21‧‧‧An angle of 45° with respect to the absorption axis of the polarizing film

22‧‧‧ 135° angle with respect to the absorption axis of the polarizing film

30‧‧‧Absorption axis of polarizing film

Claims (5)

A polarizing plate comprising: an extended optical film, a first protective film, a polarizing film and an adhesive layer; wherein an angle formed by an absorption axis of the polarizing film and a slow axis of the extended optical film The size of the first protective film in the direction of 45° with respect to the absorption axis of the polarizing film after the first protective film is allowed to stand in an environment of 85° C. for about 100° C. When the rate of change is D1 and the dimensional change rate in the direction of 135° with respect to the absorption axis of the polarizing film is D2, the following equations (1) and (2) are satisfied: |D1|≧| When D2|, 1≦|D1|/|D2|≦2 (1) |D1|<|D2|, 1<|D2|/|D1|≦2 (2). The polarizing plate according to claim 1, wherein the stretched optical film comprises a cyclic polyolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin, and (meth) At least one selected from the group consisting of acrylic resins. The polarizing plate according to claim 1 or 2, wherein the polarizing film has a thickness of 15 μm or less. The polarizing plate according to any one of claims 1 to 3, further comprising a second protective film between the polarizing film and the adhesive layer. A liquid crystal panel in which a polarizing plate according to any one of claims 1 to 4 is disposed on at least one side of a liquid crystal cell.