KR101757062B1 - Polarizing plate and liquid crystal display device - Google Patents

Abstract

It is an object of the present invention to provide a polarizing plate in which display unevenness and light leakage do not occur, and a liquid crystal display device having such a polarizing plate.
A polarizing plate having a first protective film on the light source side of the polarizer, wherein the thickness of the polarizer is 15 占 퐉 or less, the logarithmic contact angle on the light source side top surface of the polarizing plate is 100 占 or less, , The dimensional change rate (S) of the polarizing plate defined by the following formula is -1.4? S?
S = ((Dimension after heat treatment - Dimension before heat treatment) x 100) / Dimension before heat treatment

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a polarizing plate,

The present invention relates to a polarizing plate on a light source side and a liquid crystal display device.

2. Description of the Related Art In recent years, in mobile terminals such as smart phones, slimming down the entire module has been proceeding rapidly in terms of design and portability. As a matter of course, even for the polarizing plate used therefor, further reduction in thickness and weight is further demanded.

In addition, a narrow frame of the screen is progressing, and a light shielding double-faced tape (backlight tape) joining a polarizing plate on the light source side and a backlight is narrowing.

When heat is applied to the module, as described above, when the width of the backlight tape is narrow, if the adhesion between the backlight tape and the polarizer is insufficient, the polarizer can not withstand shrinkage and the backlight tape is distorted or peeled. There has been a problem that the display quality is lowered due to display unevenness or light leakage caused by the distortion or peeling.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2011-203641

Disclosure of the Invention A problem to be solved by the present invention is to provide a polarizing plate which does not cause display unevenness or light leakage and a liquid crystal display device having such a polarizing plate.

The present invention provides the following polarizing plate and a liquid crystal display device to which the polarizing plate is applied.

[1] A polarizing plate having a first protective film on a light source side of a polarizer,

The thickness of the polarizer is 15 占 퐉 or less,

The water-contact angle at the light-source-side outermost surface of the polarizing plate is 100 DEG or less,

Wherein the dimensional change ratio (S) of the polarizing plate defined by the following formula when heat treatment at a temperature of 85 占 폚 for 100 hours is -1.4? S?

S = ((Dimension after heat treatment - Dimension before heat treatment) x 100) / Dimension before heat treatment

[2] The polarizer according to [1], wherein the first protective film is a laminate of a thermoplastic resin film, a reflective polarizing film, or a thermoplastic resin film and a reflective polarizing film.

[3] A polarizer according to [1] or [2], further comprising a second protective film on the viewer side of the polarizer.

[4] The polarizer according to any one of [1] to [3], wherein the pressure-sensitive adhesive layer is provided on the outermost surface of the viewer-side side of the light source-side polarizer.

[5] A liquid crystal panel comprising a liquid crystal cell and a polarizing plate according to any one of [1] to [4] arranged on a light source side of the liquid crystal cell.

[6] A liquid crystal display device comprising a liquid crystal cell, a polarizing plate disposed on the viewer side of the liquid crystal cell, and a polarizing plate according to any one of [1] to [4] arranged on the light source side of the liquid crystal cell.

According to the polarizing plate of the present invention, even when the width of the backlight tape is narrow, when the polarizing plate is combined with the backlight module to make the liquid crystal display device, display unevenness on the surface thereof is suppressed, Is excellent in display quality.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing an example of a layer configuration of a polarizing plate and a polarizing plate with a pressure-sensitive adhesive of the present invention. Fig.
2 is a schematic cross-sectional view showing an example of the layer structure of the liquid crystal display device of the present invention.

(Polarizer)

The polarizing plate of the present invention has a polarizer. As the polarizer, an absorption type polarizing film is preferable. The thickness of the polarizer is 15 占 퐉 or less, preferably 3 to 15 占 퐉.

As the absorption type polarizing film, usually, a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film is used. The polyvinyl alcohol-based resin constituting the absorption type polarizing film is obtained by saponifying a polyvinyl acetate-based resin.

Examples of the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of other monomers copolymerizable with vinyl acetate and vinyl acetate. Other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, acrylamides having an ammonium group, and the like.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be further modified, and polyvinyl formal or polyvinyl acetal modified with aldehyde may also be used. The polymerization degree of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. Specific examples of the polyvinyl alcohol-based resin or dichroic dye include a polyvinyl alcohol-based resin and a dichroic dye exemplified in Japanese Patent Laid-Open Publication No. 159778/1989.

A film of a polyvinyl alcohol-based resin is used as a raw film of an absorption type polarizing film. The method of forming the polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a known method.

The thickness of the original film made of a polyvinyl alcohol-based resin is not particularly limited, but is, for example, 150 占 퐉 or less. In consideration of ease of drawing and the like, the film thickness is preferably 3 m or more, and more preferably 75 m or less.

The absorption type polarizing film is obtained by, for example, a step of stretching a polyvinyl alcohol based resin film in a uniaxial stretching step, dyeing the polyvinyl alcohol type resin film with a dichroic dye and adsorbing the dichroic dye, A step of treating the adsorbed polyvinyl alcohol resin film with an aqueous solution of boric acid, a step of washing with water after the treatment with the aqueous solution of boric acid, and a drying step. Further, the absorption type polarizing film may be produced, for example, by the method described in Japanese Patent Application Laid-Open No. 159778/1987. In this method, a polyvinyl alcohol-based resin layer that becomes an absorption type polarizing film can be formed by coating a base film with a polyvinyl alcohol-based resin.

(First protective film)

The polarizing plate of the present invention has a first protective film on the light source (backlight) side of the polarizer. It is preferable that the first protective film is bonded to the light source side surface of the polarizer. The light source side refers to the side of the polarizing plate closer to the backlight when a liquid crystal display is constituted by combining a member such as a liquid crystal cell, a backlight and the polarizing plate of the present invention.

Examples of the first protective film laminated on the light source side of the polarizer include a laminate of a thermoplastic resin film, a reflective polarizing film, a reflective polarizing film and a thermoplastic resin film.

(Thermoplastic resin film)

The thermoplastic resin film formed of a thermoplastic resin is preferably made of a resin having excellent transparency, uniform optical characteristics, mechanical strength, and thermal stability. Examples of the thermoplastic resin include cellulose resins such as triacetylcellulose and diacetylcellulose, polyester resins such as polyethylene terephthalate, polyethylene isophthalate and polybutylene terephthalate, polyester resins such as polymethyl (meth) acrylate, polyethyl (Meth) acrylic resins, polycarbonate resins, polyether sulfone resins, polysulfone resins, polyimide resins, polyolefin resins such as polyethylene and polypropylene, polynorbornene resins and the like . Among them, a resin film formed of a cellulose resin, a polyester resin, a (meth) acrylic resin, a polycarbonate resin, or a polyolefin resin is preferable. Here, (meth) acrylate refers to either methacrylate or acrylate, and the term "(meth)" refers to (meth) acrylic acid.

Suitable commercially available products can be used for the thermoplastic resin film.

Examples of commercially available products of the cellulose-based resin film include "Fuji-tack (registered trademark) TD80", "Fuji-takk (registered trademark) TD80UF" and "Fuji-takk (registered trademark) TD80UZ" manufactured by Fuji Film Co., Quot; KC2UAW ", "KC8UX2M "," KC8UY ", and the like.

As a commercially available product of the polyester-based resin film, "Dia Foil (registered trademark)" manufactured by Mitsubishi Juashi Co., Ltd., "LUMIRA (registered trademark)" manufactured by Toray Industries, Cosmo Shine (registered trademark) "and the like.

Commercially available products of the (meth) acrylic resin film include "Technoloy (registered trademark)" manufactured by Sumitomo Chemical Co., Ltd., and "Acryprene (registered trademark)" manufactured by Mitsubishi Rayon Kabushiki Kaisha.

As a commercially available product of the polycarbonate resin film, "PANLITE (registered trademark)" manufactured by Teijin Ltd. may be mentioned.

Commercially available polyolefin resins include "Topas" manufactured by Topas Advanced Polymers GmbH and sold by Polyplastics Corporation, "ARTON" (registered trademark) sold by JSR Corporation, Nippon Zeon "ZEONOR (registered trademark)", "ZEONEX (registered trademark)" sold by Kabushiki Kaisha, "APEL" (registered trademark) sold by Mitsui Chemicals, Inc. , All trade names), and the like, and a film can be produced from the resin.

A commercially available polyolefin-based resin film may be used. For example, "ATSON FILM" sold by JSR Kabushiki Kaisha ("ATSON" is a registered trademark of Sekisui Chemical Co., Ltd.) and sold by Sekisui Chemical Co., Ltd. , And "Zeonoa" (registered trademark) sold by Nippon Zeon Co., Ltd., and the like.

The thickness of the thermoplastic resin film is usually 5 to 100 占 퐉, preferably 10 to 50 占 퐉, and more preferably 10 to 30 占 퐉.

(Reflective polarizing film)

Examples of the reflective polarizing film include a grid-type polarizing film, a multilayer thin film laminate of two or more layers made of two or more materials having a refractive index difference, an evaporated multilayer thin film having a different refractive index used for a beam splitter, A film obtained by stretching a laminate of two or more layers of resins using two or more resins having birefringence, a film for separating the polarization direction by reflecting / transmitting linearly polarized light in the axial direction orthogonal to the polarization direction, etc. .

Examples of the reflection type polarizing film include a material that generates retardation by stretching represented by polyethylene naphthalate, polyethylene terephthalate, or polycarbonate, an acrylic resin typified by polymethyl methacrylate, or an acrylic resin represented by "Atton " manufactured by JSR Kabushiki Kaisha And a norbornene resin represented by "(registered trademark) ", which is a resin obtained by uniaxially stretching a resin having a small amount of retardation expressed in turn as a multilayer laminate. Examples of commercially available reflective polarizing films include "DBEF" (registered trademark), "APF-V3" (product name) and "APFV2" (product name) manufactured by 3M Company. The thickness of the reflective polarizing film is usually 5 to 100 占 퐉, preferably 10 to 50 占 퐉, and more preferably 10 to 30 占 퐉.

(Laminate of reflection type polarizing film / thermoplastic resin film)

The laminate of the reflection type polarizing film and the thermoplastic resin film may be a laminate obtained by bonding the above-mentioned film through a pressure-sensitive adhesive or an adhesive. As the pressure-sensitive adhesive or the adhesive, a well-known one may be selected. From the viewpoints of simplicity of bonding work and prevention of optical distortion, it is preferable to use a pressure-sensitive adhesive. As the pressure-sensitive adhesive, a pressure-sensitive adhesive using an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyether, or the like as a base polymer can be adopted. Is excellent in optical transparency, maintains a proper cohesive force, is excellent in adhesion to a reflective polarizing film and a thermoplastic resin film, has good heat resistance, and does not cause peeling problems such as peeling off or peeling in a high temperature environment , A pressure-sensitive adhesive using an acrylic polymer as a base polymer is preferable.

The pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive may contain a filler such as fine particles showing light scattering property, glass fiber, glass bead, resin bead, metal powder or other inorganic powder, pigment, coloring agent, antioxidant, good. Examples of the ultraviolet absorber include a salicylic ester compound, a benzophenone compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound.

The hard coat layer may be formed on the side of the first protective film opposite to the side joined to the polarizer in the first protective film. A first protective film having a hard coat layer is also included in the first protective film. By the hard coat layer, it is possible to prevent scratches or the like which are generated when the polarizing plate is processed.

Since the hard coat layer has a small dimensional change, the change in dimension of the polarizing plate can be further suppressed by providing the hard coat layer. In addition, since a large factor contributing to the dimensional change rate of the polarizing plate is the polarizer, it is preferable to form the hard coat layer at a position close to the polarizer in that the dimensional change of the polarizing plate can be suppressed more effectively. It is presumed that the hard coat layer can suppress the dimensional change of the polarizer, but this estimation does not limit the present invention at all. From this point of view, the distance between the polarizer and the hard coat layer is preferably 30 占 퐉 or less, more preferably 25 占 퐉 or less.

It is preferable that no pressure-sensitive adhesive layer is present between the hard coat layer and the polarizer from the viewpoint that the dimensional change of the polarizing plate can be suppressed. When there is no layer having a small elastic modulus such as a pressure-sensitive adhesive layer between the hard coat layer and the polarizer, the hard coat layer can effectively suppress the dimensional change of the polarizer.

When the hard coat layer is formed, the thickness of the hard coat layer is preferably 1 to 8 占 퐉, more preferably 1 to 6 占 퐉, from the viewpoint of achieving both protection and bendability. When the thickness of the hard coat layer is more than 8 占 퐉, the flexibility tends to be low and cracks tend to occur at the time of bending. On the other hand, when the thickness of the hard coat layer is less than 1 탆, flexibility is good, but sufficient characteristics can not be obtained from the viewpoint of in-plane uniformity.

The hard coat layer can be formed as a resin coating layer. As the resin forming the resin coating layer, a resin having sufficient strength as a film after forming the resin coating layer and having transparency can be used. Examples of the resin include an active energy ray-curable resin such as a thermosetting resin, a thermosetting resin, an ultraviolet ray curable resin, and an electron beam curable resin, and a diphasic mixed resin. Above all, a resin can be cured by irradiation of ultraviolet rays, a resin coating layer can be formed efficiently by a simple processing operation, and a light diffusion layer such as an antiglare treatment layer can be formed. Therefore, an ultraviolet curable resin is preferable . Examples of the ultraviolet curable resin include a polyester type, an acrylic type, an urethane type, an amide type, a silicone type, and an epoxy type.

The wettability (contact angle of water droplets) of the hard coat layer can be controlled by a known method such as adding an additive to the resin (coating liquid).

As a method of forming the hard coat layer, a well-known method can be adopted, and for example, a method of coating the above resin (coating liquid) on the first protective film and drying can be mentioned. When a curable resin is used as the resin for forming the resin coating layer, the resin is cured after being coated. As the coating method of the coating liquid, fountain, die coater, casting, spin coat, fountain metering, gravure and the like can be adopted. In the coating, the coating liquid may be diluted with a common solvent such as toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, ethyl alcohol or the like, and may not be diluted.

In the polarizing plate of the present invention, the contact angle of the water droplet on the outermost surface of the light source side obtained from the above-mentioned film is 100 DEG or less. The contact angle of the water droplet is preferably 90 DEG or less. It is more preferable that the contact angle of the water droplet is 70 DEG or less. Such wettability can be controlled by appropriately selecting the resin film and bonding it to the outermost surface of the polarizing plate. It is possible to improve the adhesion between the light source sheet and the polarizing plate and to suppress the display unevenness of the display device caused by the distortion of the backlight tape if the polarizing plate has the outermost surface having a contact angle of water drops of 100 DEG or less. In the present specification, the contact angle refers to the contact angle measured by the? / 2 method when 1 占 퐇 of pure water is dropped on the surface.

(Second protective film)

It is preferable that the polarizing plate of the present invention further includes a second protective film on the side opposite to the light source side of the polarizer, i.e., on the viewer side. It is more preferable to laminate the second protective film on the visual side surface. When a liquid crystal display device is constituted by combining a polarizing plate of the present invention with a member such as a liquid crystal cell, a backlight and the like, the viewing side surface is a surface facing away from the backlight, that is, a surface opposite to the backlight side . The second protective film may be a film such as the above thermoplastic resin film. When the first protective film is a thermoplastic resin film, the second protective film may be the same as or different from the first protective film.

(Polarizer)

The polarizing plate of the present invention is a polarizing plate having a first protective film on the light source side of the polarizer. And a polarizing plate having a second protective film on the viewer's side of the polarizer. As a method of laminating the first and / or second protective films on the polarizer, a method of bonding with an adhesive or a pressure sensitive adhesive is generally adopted. As described above, it is preferable to use an adhesive for the lamination of the polarizer and the first protective film or the second protective film from the viewpoint that the dimensional change of the polarizer can be further suppressed. When a protective film is laminated on both sides of the polarizer, a homogeneous adhesive or a pressure sensitive adhesive may be used, or a different kind of adhesive or pressure sensitive adhesive may be used.

Examples of the adhesive include an aqueous adhesive, a photo-curable adhesive, and the like. The water-based adhesive may be an adhesive in which the adhesive component is dissolved in water, or an adhesive in which the adhesive component is dispersed in water, so that the adhesive layer can be made thin. As the water-based adhesive, an aqueous adhesive in which the main component of the adhesive (composition) is a polyvinyl alcohol-based resin or a urethane resin is preferable.

The polyvinyl alcohol-based resin may be a partially saponified polyvinyl alcohol or a fully saponified polyvinyl alcohol as well as a modified polyvinyl alcohol such as a carboxyl group-modified polyvinyl alcohol, an acetacetyl group-modified polyvinyl alcohol, a methylol group-modified polyvinyl alcohol, Or a polyvinyl alcohol-based resin. When a polyvinyl alcohol-based resin is contained as an adhesive component, the adhesive is often prepared as an aqueous solution of a polyvinyl alcohol-based resin. The concentration of the polyvinyl alcohol-based resin in the adhesive is usually about 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of water.

To the adhesive containing the polyvinyl alcohol-based resin as the main component, a curing component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent is preferably added in order to improve the adhesiveness. Examples of water-soluble epoxy resins include polyamide polyamines obtained by reacting epichlorohydrin with polyamide polyamines obtained by reacting polyalkylene polyamines such as diethylene triamine and triethylene tetramine with dicarboxylic acids such as adipic acid Epoxy resins and the like. Commercially available products of such polyamidepolyamine epoxy resins include Sumirez resin (registered trademark) 650 (30), Sumirez resin (registered trademark) 675 sold by Taoka Kagaku Kogyo Co., Ltd., Hoshimitsu PMC And "WS-525 ", which is commercially available from Kagaku Kogyo Co., Ltd., and these commercially available products can be suitably used. The addition amount of the curable component or the crosslinking agent is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight, based on 100 parts by weight of the polyvinyl alcohol-based resin. When the addition amount is small, the adhesive property improving effect is small. On the other hand, when the addition amount is large, the adhesive layer tends to be sagged.

The laminate bonded through the water-based adhesive is usually dried, and the adhesive layer is dried and cured. The drying treatment can be carried out, for example, by blowing hot air. The drying temperature is usually 40 to 100 ° C, preferably 60 to 100 ° C. The drying time is, for example, about 20 to 1,200 seconds. The thickness of the adhesive layer after drying is usually about 0.001 to 5 占 퐉, preferably 0.01 占 퐉 or more, more preferably 2 占 퐉 or less, further preferably 1 占 퐉 or less. If the thickness of the adhesive layer is excessively large, the appearance of the polarizing plate tends to be defective.

After the drying treatment, sufficient curing strength may be obtained by curing at room temperature or more for at least half a day, usually for at least one day. Such curing is typically carried out in a rolled-up state. The preferable curing temperature is usually 30 to 50 占 폚, more preferably 35 to 45 占 폚. When the curing temperature exceeds 50 캜, so-called " tightening " occurs in the rolled-up state. It is preferable that the humidity at the time of curing is appropriately selected so that the relative humidity becomes, for example, 70% or less. The curing time is usually about 1 to 10 days, preferably about 2 to 7 days.

Examples of the photo-curable adhesive include a mixture of a photo-curable epoxy resin and a photo cationic polymerization initiator. Examples of the photocurable epoxy resin include alicyclic epoxy resins, epoxy resins not having an alicyclic structure, and mixtures thereof. As the photo-curing adhesive, an adhesive in which a radical polymerization initiator and / or a cationic polymerization initiator is added to an epoxy resin, an acrylic resin, an octacene resin, a urethane resin, or a polyvinyl alcohol resin can also be used.

The laminated body laminated through the photo-curing adhesive is cured after the lamination by irradiating the active energy ray. The light source of the active energy ray is preferably an active energy ray having a light emission distribution at a wavelength of 400 nm or less. Specific examples thereof include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a high pressure mercury lamp, a chemical lamp, a black light lamp, A metal halide lamp or the like can be preferably used. The intensity of light irradiation to the photo-curing adhesive is appropriately determined by the composition of the photo-curable adhesive, but it is preferable that the irradiation intensity in the wavelength range effective for activation of the photo cationic polymerization initiator is 0.1 to 6,000 mW / cm 2. When the irradiation intensity is not less than 0.1 mW / cm 2, the reaction time does not become too long. When the irradiation intensity is less than 6,000 mW / cm 2, the heat radiated from the light source and the heat generated upon curing of the photocurable adhesive deteriorate the yellowing of the epoxy resin or deterioration of the polarizing plate It is desirable in that it is less likely to cause it.

The light irradiation time to the photo-curing adhesive is controlled for each photo-curable adhesive to be cured, but it is preferable that the accumulated light quantity expressed by the product of the irradiation intensity and the irradiation time is set to 10 to 10,000 mJ / cm2. When the total amount of light to the photo-curing adhesive is 10 mJ / cm 2 or more, sufficient activation species derived from the polymerization initiator are generated sufficiently to allow the curing reaction to proceed more surely. When the amount is 10,000 mJ / cm 2 or less, the irradiation time is not excessively long , Which is preferable in that good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually 0.001 to 5 占 퐉, preferably 0.01 占 퐉 to 3 占 퐉.

The pressure-sensitive adhesive is required to satisfy various properties necessary for the optical film (transparency, durability, recyclability, etc.), and contains a (meth) acrylic acid ester as a main component and a , An acrylic resin having a glass transition temperature (Tg) of 0 占 폚 or less and an acrylic pressure-sensitive adhesive containing a crosslinking agent can be used.

An example of the configuration of the polarizing plate of the present invention will be described with reference to Fig. 1, the adhesive layer between the polarizer and the protective film is not shown. The polarizing plate 10 shown in Fig. 1A is a polarizing plate having a first protective film 3 on the light source side of the polarizer 1. The polarizing plate 10 shown in Fig. 1B has a first protective film 3 on the light source side of the polarizer 1 and a second protective film 5 on the viewer side of the polarizer 1 .

The polarizing plate of the present invention has a dimensional change rate (S) of -1.4? S? 0.0 when the heat treatment is performed at a temperature of 85 占 폚 for 100 hours from the viewpoint of adhesion with the backlight tape.

S = ((Dimension after heat treatment - Dimension before heat treatment) x 100) / Dimension before heat treatment

The dimensional change rate (S) of the polarizing plate refers to the rate of dimensional change with the largest absolute value among the dimensional change rates in an arbitrary direction in the plane of the polarizing plate. Specifically, the length L1 from an arbitrary point x1 to point x2 in the in-plane direction of the polarizing plate before heat treatment is measured, and the length L2 from the point x1 to the point x2 after the heat treatment is measured. Then, the rate of change of the length L2 based on the length L1 is found. Among the rate of change in the in-plane direction of the polarizing plate thus obtained, the rate of change in which the absolute value is largest is the rate of dimensional change (S). When the absorption type polarizing film is used as the polarizer, the dimensional change ratio S usually corresponds to the rate of change of the length in the drawing direction of the absorption type polarizing film, that is, in the absorption axis direction. The polarizing plate satisfying the dimensional change rate can be obtained, for example, by reducing the thickness of the polarizer or appropriately selecting the type and thickness of the protective film of the polarizing plate.

(Polarizer with adhesive)

Another mode of the pressure-sensitive adhesive-attached polarizer of the present invention has a pressure-sensitive adhesive layer on one side of the polarizer of the present invention. The pressure-sensitive adhesive layer may be directly laminated on the polarizer, and when the polarizer and the protective film are laminated, they may be laminated on the protective film.

1 (A) and 1 (B), an example of the polarizing plate with a pressure-sensitive adhesive of the present invention will be described. A polarizing plate 20 with a pressure sensitive adhesive shown in Fig. 1 (A) has a polarizing plate 10 having a first protective film 3 on the light source side surface of the polarizer 1, Sensitive adhesive layer (15). 1 (B) has a first protective film 3 on the light source side of the polarizer 1 and a second protective film 5 on the visual side of the polarizer 1 , And a pressure-sensitive adhesive layer (15) on the visual side surface of the second protective film.

The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is required to satisfy various properties (transparency, durability, reworkability, etc.) necessary for the optical film, and it is preferable that the pressure-sensitive adhesive contains (meth) acrylic acid ester as a main component, ) Acrylic resin having an acrylic monomer having a glass transition temperature (Tg) of 0 占 폚 or less and an acrylic pressure-sensitive adhesive containing a crosslinking agent, obtained by radical polymerization of an acrylic monomer composition containing an acrylic monomer in the presence of a polymerization initiator.

(Liquid crystal display device)

The above-mentioned polarizer with a pressure-sensitive adhesive may be suitably used for a liquid crystal display device. 2 (A) and 2 (B), an example of the configuration of a liquid crystal display device of another form of the present invention will be described. The liquid crystal display device 55 shown in Fig. 2A is constructed such that the polarizing plate 20 with a pressure sensitive adhesive of the present invention is laminated on the side of the backlight 50 side of the liquid crystal cell 30 through the pressure sensitive adhesive, (Viewing side) 25 is laminated on the viewing side surface of the liquid crystal display panel 30 through the same or different pressure sensitive adhesive layer as that of the above-mentioned pressure sensitive adhesive. The polarizing plate 20 used in FIG. 2A is a polarizing plate with a pressure-sensitive adhesive having a first protective film on the light source side surface of the polarizer. The polarizing plate (viewer side) 25 may be a polarizing plate of the present invention or a known polarizing plate. The liquid crystal cell 30 may be any conventionally known mode such as an IPS mode, a VA mode, and a TN mode. The liquid crystal display device 55 further includes a light diffusion plate 40 between the backlight 50 and the polarizing plate 20 of the present invention.

The liquid crystal display device 55 shown in Fig. 2B includes a polarizing plate 20 having a polarizing plate with a pressure-sensitive adhesive having a first protective film on the light source side of the polarizer and a second protective film on the viewer side And is a liquid crystal display device having the same configuration as that of Fig. 2A except that it is used.

[Example]

The present invention has been described in more detail with reference to the following examples, but the present invention is not limited by these examples. In the examples,% and parts indicating the content or amount are based on weight unless otherwise specified.

(1) Measurement of logarithmic contact angle

The polarizing plate was set horizontally on a contact angle meter (image processing contact type "FACE CA-X type" manufactured by Kyowa Chemical Co., Ltd.) such that the light source side was the upper face, and 1 μl of pure water was dropped onto the surface to be measured , and the logarithmic contact angle was measured by the? / 2 method.

(2) Dimensional change rate of polarizer

The polarizing plate was cut into squares of 100 mm square each having 100 mm in the direction of the absorption axis and 100 mm in the direction of the transmission axis, and left for 100 hours in an environment of 85 캜. The dimensions of the polarizing plate were measured by a two-dimensional measuring machine "NEXIV (registered trademark) VMR-12072" manufactured by Nikon Corporation. The dimensional change rate S of the polarizing plate is calculated by the following formula.

S = ((Dimension after heat treatment - Dimension before heat treatment) x 100) / Dimension before heat treatment

(3) Visibility test of display stains

Sensitive adhesive-attached polarizing plate was peeled off from the back surface (light source side) of a liquid crystal cell of an IPS mode liquid crystal display device (product name "iPad2", manufactured by Apple Corporation), and the polarizing plate with a pressure- So as to coincide with the absorption axis direction of the polarizing plate adhered to the cell, thereby fabricating a liquid crystal panel. Next, a backlight tape having a width of 1 mm was bonded to the periphery of the light-source-side polarizing plate, and this liquid crystal panel was returned to the liquid crystal display device to produce a liquid crystal display device.

The produced liquid crystal display was allowed to stand in an environment at 85 캜 for 100 hours, and then the display unevenness was visually observed in a bright room. The evaluation criteria are as follows.

?: No display unevenness was observed.

?: Slight display unevenness was observed.

?: Display unevenness is observed.

X: Strong display unevenness is observed.

≪ Example 1 >

(Production of polarizing plate)

A polyvinyl alcohol film (average degree of polymerization of about 2400, saponification degree of 99.9 mol% or more) having a thickness of 20 占 퐉 was uniaxially stretched by 5 times by dry stretching and immersed in pure water at 60 占 폚 for 1 minute And then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. And then immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds, and then dried at 65 DEG C to obtain an absorption type polarizing film having a thickness of 7 mu m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

Subsequently, 3 parts of a carboxyl group-modified polyvinyl alcohol (trade name "KL-318" available from Kabushiki Kaisha Kurara Co., Ltd.) was dissolved in 100 parts of water on the light source side of the obtained absorption type polarizing film, Based adhesive to which 1.5 parts of a polyamide epoxy additive (Sumirez Resin 650 (30), an aqueous solution having a solid content concentration of 30%, obtained from Daokakagaku Kogyo K.K.), which is a water-soluble epoxy resin, 1 triacetylcellulose film having a thickness of 25 占 퐉 (trade name "KC2UAW", available from Konica Minolta Kabushiki Kaisha) as a first protective film was bonded to the viewer side of the polarizer using the above-mentioned water-based adhesive as a second protective film, (Trade name " ZEONOR (registered trademark) " obtained from Nippon Zeon Co., Ltd.) was bonded to obtain a polarizing plate. The logarithmic contact angle and the rate of dimensional change (S) in the stretching direction of the polarizing plate were measured for the obtained polarizing plate.

A visibility test for display unevenness was performed using a pressure-sensitive adhesive-attached polarizing plate obtained by laminating a commercially available acrylic pressure-sensitive adhesive sheet having a thickness of 20 mu m as a pressure-sensitive adhesive layer on the viewer side of the polarizing plate.

≪ Example 2 >

A commercially available acrylic pressure sensitive adhesive sheet having a thickness of 5 占 퐉 was laminated on a triacetylcellulose film (first protective film) of the polarizing plate obtained in Example 1, and a 26 占 퐉 -thick reflective polarizing film Quot; Advanced Polarized Film, Version 3 (APF-V3) "obtained from 3M Company) were bonded to form a first protective film. The visibility of the logarithmic contact angle, the dimensional change, and the display unevenness were tested in the same manner as in Example 1 except that the above-mentioned laminate was used as a polarizing plate.

≪ Example 3 >

A polyvinyl alcohol film having a thickness of 30 占 퐉 (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching and kept at 60 占 폚 pure water for 1 minute And immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. And then immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds and then dried at 65 DEG C to obtain an absorption type polarizing film having a thickness of 12 mu m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

A triacetyl cellulose film (trade name " KC2UAW ", available from Konica Minolta K.K.) having a thickness of 25 mu m was bonded as a first protective film to the light source side of this absorption type polarizing film through the water-based adhesive described in Example 1, A film made of a norbornene resin having a thickness of 15 占 퐉 (trade name "ATON (registered trademark)" obtained from JSR Corporation) as a second protective film was adhered to the viewer side of the polarizer through an aqueous adhesive described in Example 1 To obtain a polarizing plate. A visibility test of logarithmic contact angle, dimensional shrinkage, and display unevenness was carried out in the same manner as in Example 1 except that the above-mentioned polarizing plate was used.

<Example 4>

A polyvinyl alcohol film having a thickness of 30 占 퐉 (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching and kept at 60 占 폚 pure water for 1 minute And immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. And then immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds, and then dried at 65 DEG C to obtain an absorption type polarizing film having a thickness of 12 m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

On the visible side of this absorption type polarizing film, a film made of a norbornene resin having a thickness of 13 占 퐉 as a second protective film (trade name: ZEONOR (trade name, available from Nippon Zeon Co., Ltd.) Trademark &quot;). Thereafter, an acrylic pressure-sensitive adhesive sheet having a thickness of 5 占 퐉 was laminated on the light source side of the polarizer, and a 26 占 퐉 -thick reflection polarizing film (APF-V3) was bonded as a first protective film through the pressure- A polarizing plate was obtained. A visibility test of logarithmic contact angle, dimensional shrinkage, and display unevenness was carried out in the same manner as in Example 1 except that the above-mentioned laminate was used as a polarizing plate.

&Lt; Example 5 >

A polyvinyl alcohol film having a thickness of 30 占 퐉 (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching and kept at 60 占 폚 pure water for 1 minute And immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. And then immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds, and then dried at 65 DEG C to obtain an absorption type polarizing film having a thickness of 12 m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

A triacetyl cellulose film (trade name &quot; KC2UAW &quot;, available from Konica Minolta K.K.) having a thickness of 25 mu m was bonded as a first protective film to the light source side of this absorption type polarizing film through the water-based adhesive described in Example 1. A hard coat layer is provided on one side of the first protective film. The first protective film and the absorptive polarizing film are bonded to each other in such a manner that a surface, to which the hard coat layer is not provided, Respectively. A film made of a norbornene resin having a thickness of 23 占 퐉 (trade name "ZEONOR (registered trademark)", available from Nippon Zeon Co., Ltd.) as a second protective film was laminated on the viewer side of the polarizer through the aqueous adhesive described in Example 1, To obtain a polarizing plate. A visibility test of logarithmic contact angle, dimensional shrinkage, and display unevenness was carried out in the same manner as in Example 1 except that the above-mentioned polarizing plate was used.

&Lt; Example 6 >

A polyvinyl alcohol film having a thickness of 30 占 퐉 (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching and kept at 60 占 폚 pure water for 1 minute And immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. And then immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds and then dried at 65 DEG C to obtain an absorption type polarizing film having a thickness of 12 mu m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

A triacetyl cellulose film (trade name &quot; KC2UAW &quot;, available from Konica Minolta K.K.) having a thickness of 25 mu m was bonded as a first protective film to the light source side of this absorption type polarizing film through the water-based adhesive described in Example 1. A hard coat layer is provided on one side of the first protective film. The first protective film and the absorptive polarizing film are bonded to each other in such a manner that a surface, to which the hard coat layer is not provided, Respectively. A film made of a norbornene resin having a thickness of 15 占 퐉 (trade name "ATON (registered trademark)", available from JSR Corporation) as a second protective film was coated on the viewer side of the polarizer through the aqueous adhesive described in Example 1 And a polarizing plate was obtained. A visibility test of logarithmic contact angle, dimensional shrinkage, and display unevenness was carried out in the same manner as in Example 1 except that the above-mentioned polarizing plate was used.

&Lt; Comparative Example 1 &

A hard coat layer was provided on the surface of the reflective polarizing film in the polarizing plate obtained in Example 2 to obtain a polarizing plate. The polarizing plate was subjected to visually observing the logarithmic contact angle, the dimensional change rate, and the display unevenness in the same manner as in Example 2. [

&Lt; Comparative Example 2 &

A polyvinyl alcohol film having a thickness of 60 占 퐉 (average degree of polymerization of about 2400, degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching and kept at 60 占 폚 pure water for 1 minute And immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. And then immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C for 300 seconds. Subsequently, the film was washed with pure water at 26 DEG C for 20 seconds and then dried at 65 DEG C to obtain an absorption type polarizing film having a thickness of 23 mu m in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

A triacetyl cellulose film (trade name &quot; KC2UAW &quot;, available from Konica Minolta K.K.) having a thickness of 25 mu m was bonded as a first protective film to the side of the light source side of the absorption type polarizing film through the aqueous adhesive prepared above, A film made of a norbornene resin having a thickness of 23 占 퐉 (trade name "ZEONOR (registered trademark)" available from Nippon Zeon Co., Ltd.) as a second protective film was bonded to the side of the viewer side with the above adhesive, .

A visibility test of logarithmic contact angle, dimensional shrinkage, and display unevenness was carried out in the same manner as in Example 1 except that the above-mentioned polarizing plate was used.

1: Polarizer
3: First protective film
5: Second protective film
10: polarizer
15: Pressure-sensitive adhesive layer
20: Polarizer with adhesive
25: polarizing plate (viewer side)
30: liquid crystal cell
40: light diffuser plate
50: Backlight
55: liquid crystal display

Claims (6)

A polarizing plate disposed on the light source side of the liquid crystal cell and having a first protective film on the light source side of the polarizer and a hard coat layer on the light source side of the first protective film,
The thickness of the polarizer is 15 占 퐉 or less,
The water-contact angle at the light-source-side outermost surface of the polarizing plate is 100 DEG or less,
Wherein the dimensional change ratio (S) of the polarizing plate defined by the following formula when heat treatment at a temperature of 85 占 폚 for 100 hours is -1.4? S?
S = ((Dimension after heat treatment - Dimension before heat treatment) x 100) / Dimension before heat treatment The polarizing plate according to claim 1, wherein the first protective film is a laminate of a thermoplastic resin film, a reflective polarizing film, or a thermoplastic resin film and a reflective polarizing film. The polarizer according to claim 1 or 2, further comprising a second protective film on the viewer side of the polarizer. The polarizer according to any one of claims 1 to 4, further comprising a pressure-sensitive adhesive layer on the outermost surface of the viewer-side side of the light-source-side polarizer. A liquid crystal panel comprising a liquid crystal cell and the polarizing plate according to claim 1 or 2, which is disposed on a light source side of the liquid crystal cell. A liquid crystal display device comprising a liquid crystal cell, a polarizing plate disposed on the viewer side of the liquid crystal cell, and a polarizing plate according to claim 1 or 2 disposed on the light source side of the liquid crystal cell.

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