TW201426035A - Polarizing plate, optical film and image display - Google Patents

Abstract

A polarizing plate of the present invention comprises a polarizer; an adhesive layer; and a transparent protective film bonded to at least one side of the polarizer with the adhesive layer interposed there between, wherein the adhesive layer is formed from an active energy ray curing adhesive containing at least one curable component, and the adhesive layer has a glass transition temperature (Tg) of 60 DEG C. or more, and a thickness of 0.01 μm to 7 μm. The polarizing plate has sufficient durability in a severe environment at high temperature and high humidity.

Description

Polarizer, optical film and image display device

The present invention relates to a polarizing plate. The polarizing plate can be formed as a liquid crystal display (LCD), an organic EL (electroluminescence) display device, or a CRT (Cathode Ray Tude), either alone or as an optical film laminated thereon. , PDP (Plasma Display Panel) and other image display devices.

In the watch, mobile phone, PDP, notebook computer, monitor for personal computer, DVD (digital versatile disc) player, TV (TeleVision, TV), etc., the market for liquid crystal display devices is in a hurry Unfolding. A liquid crystal display device is a device that visualizes a polarization state generated by conversion of a liquid crystal, and a polarizer is used in view of its display principle. In particular, in applications such as TVs, high brightness, high contrast, and wide viewing angle are increasingly required, and high transmittance, high degree of polarization, high color reproducibility, and the like are increasingly required for polarizing plates.

As the polarizer, for example, an iodine-based polarizer having a structure in which iodine is adsorbed and extended in polyvinyl alcohol has high transmittance and high degree of polarization, and is widely used as a most commonly used polarizer. In general, a polarizing plate is used for bonding a transparent protective film by a so-called water-based adhesive which is formed by dissolving a polyvinyl alcohol-based material in water on both surfaces of a polarizer (Patent Document 1 and Patent Document 2). As the transparent protective film, triacetyl cellulose or the like having a high moisture permeability is used.

However, as described above, when a polarizing plate is produced, when a water-based adhesive such as a polyvinyl alcohol-based adhesive is used, after bonding the polarizer and the transparent protective film, A drying step is required. The drying step existing in the manufacturing steps of the polarizing plate or the like is disadvantageous for improving the productivity of the polarizing plate.

Further, when a water-based adhesive (so-called wet laminate) is used, in order to improve the adhesion to the adhesive, the moisture content of the polarizer is not relatively increased (usually, the moisture content of the polarizer is about 30%). However, a polarizing plate which is formed by a water-based adhesive and has good adhesion is not obtained. However, the polarizing plate obtained in this manner has a problem that the dimensional change is large in a high-temperature or high-temperature and high-humidity environment. On the other hand, in order to suppress the above dimensional change, the water content of the polarizer can be lowered, or a transparent protective film having a low moisture permeability can be used. However, when such a polarizer and a transparent protective film are bonded using a water-based adhesive, the efficiency of the drying step is lowered, or the polarizing characteristics are lowered, or the appearance is poor, and a substantially useful polarizing plate cannot be obtained.

In particular, as in the case of the TV, in recent years, as the image display device tends to be larger, the size of the polarizing plate has become very large in terms of productivity and cost (increased cost rate and number of acquisitions). important. However, in the polarizing plate using the above-described water-based adhesive, there is a problem in that the size of the polarizing plate changes due to the heat of the backlight, which becomes a spot such that black appears in one part of the entire screen. The so-called light leakage (light spot) such as whitish becomes remarkable.

For the above reasons, it has been proposed to use an active energy ray-curing type (especially an ultraviolet curing type) adhesive instead of a water-based adhesive. For example, as an adhesive agent, an ultraviolet curable adhesive using an acrylic acid or a methacrylic monomer as a diluent in an acrylic oligomer such as epoxy acrylate, urethane acrylate or polyester acrylate is proposed ( Patent Document 3).

Further, the durability required for the polarizing plate can be made strict, and durability in a more severe environment of high humidity and high temperature is required. However, the polarizing plate described above cannot satisfy the durability in the above-mentioned harsh environment.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-220732

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2001-296427

[Patent Document 3] Japanese Patent Laid-Open No. 61-246719

It is an object of the present invention to provide a polarizing plate which can satisfy the durability in a harsh environment of high humidity and high temperature.

Further, an object of the present invention is to provide an optical film in which the polarizing plate is laminated, and an image display device such as a liquid crystal display device using the polarizing plate or the optical film.

The present inventors have made intensive studies to solve the above problems, and as a result, have found that the above object can be attained by the polarizing plate shown below, and the present invention has been completed.

That is, the present invention relates to a polarizing plate which is provided with a transparent protective film on at least one surface of a polarizer via an adhesive layer, wherein the adhesive layer is cured by an active energy ray containing at least one hardening component. The agent is formed, and the Tg of the adhesive layer is 60 ° C or more, and the thickness of the adhesive layer is 0.01 to 7 μm.

In the above polarizing plate, it is preferred that the Tg (° C.) of the adhesive layer is defined as A, and the thickness (μm) of the adhesive layer is defined as B, and the numerical formula (1) is satisfied: A-12× B>58.

In the above polarizing plate, it is preferred that the adhesive layer has a gel fraction of 50% by weight or more.

In the above polarizing plate, it is preferred that the curable component is a compound having a (meth) acrylonitrile group.

In the above polarizing plate, as the curable component, it is preferred to use a formula (1): CH ₂ = C(R ¹ )-CONR ² (R ³ ) (R ¹ represents a hydrogen atom or a methyl group, R ² a straight or branched alkyl group having a hydrogen atom or a hydroxy, fluorenyl, amine or quaternary ammonium group having 1 to 4 carbon atoms, and R ³ represents a hydrogen atom or a straight 1 to 4 carbon atom a chain or a branched alkyl group, which does not contain R ² and R ³ as a hydrogen atom, or R ² and R ^{3 are} bonded to form a 5-membered ring or a 6-membered ring which may also contain an oxygen atom. N-substituted amide monomer.

Preferably, the above N-substituted guanamine monomer is selected from the group consisting of N-hydroxyethyl acrylamide, N-methylol acrylamide, N-isopropyl acrylamide, and N-propenyl morpholine. At least one of them. Particularly preferably, the N-substituted amide-based monomer contains N-hydroxyethyl acrylamide and N-propenyl morpholine. When N-hydroxyethyl acrylamide and N-propenyl morpholine are used in combination, it is preferred that the ratio of N-hydroxyethyl acrylamide is 40% by weight or more based on the total amount.

Further, in the N-substituted amide-based monomer, a monofunctional (meth) acrylate having an aromatic ring and a hydroxyl group may be used in combination as the curable component.

In the above polarizing plate, it is preferred that the active energy ray-curable adhesive is an electron beam curing type adhesive.

In the above polarizing plate, it is preferred that the transparent protective film be at least one selected from the group consisting of a cellulose resin, a polycarbonate resin, a cyclic polyolefin resin, and a (meth)acrylic resin.

The present invention further relates to an optical film characterized in that at least one of the above polarizing plates is laminated.

The present invention further relates to an image display device characterized by using the above polarizing plate or the above optical film.

In the polarizing plate of the present invention, an active energy ray-curable adhesive is used as an adhesive for bonding the polarizing plate and the transparent protective film. The active energy ray-curable adhesive has higher durability than the aqueous adhesive. Further, in the polarizing plate of the present invention, as the active energy ray-curable adhesive, the Tg of the adhesive layer formed therefrom is used at an activity of 60 ° C or higher. The energy ray-curable adhesive is controlled to have a thickness of the adhesive layer of 0.01 to 7 μm. As described above, in the polarizing plate of the present invention, an active energy ray-curable adhesive having a high Tg of the adhesive layer of 60 ° C or higher is used, and the thickness of the adhesive layer is controlled to the above range, thereby satisfying the above. Durability in harsh environments such as wet and hot. In particular, when the Tg (° C.) of the adhesive layer is defined as A and the thickness (μm) of the adhesive layer is defined as B, when the numerical formula (1): A-12×B>58 is satisfied, The above durability is preferred.

The active energy ray-curable adhesive used for the above polarizing plate is preferably an electron beam hardening type adhesive. The electron beam hardening type adhesive is more productive than the ultraviolet light curing type adhesive, and can be used by an electron beam (ie, dry buildup) in a hardening method for an adhesive for bonding a polarizer and a transparent protective film. The heating step in the ultraviolet curing method is not required, so that productivity can be greatly improved. Further, by using an electron beam curing type adhesive, the durability of the polarizing plate can be further improved as compared with the ultraviolet curing type adhesive.

Further, when a compound having a (meth)acryl fluorenyl group, particularly a curable component using the above N-substituted amide-based monomer as an active energy ray-curable adhesive, is used, the curable component is superior in durability. Preferably, it is especially preferred as an electron beam hardening type adhesive. For example, when a polarizer having a low water content is used, or when a material having a low moisture permeability is used as a transparent protective film, the electron beam hardening adhesive exhibits good adhesion to the same, and the result is obtained. A polarizing plate with good dimensional stability.

In the case of using the above-mentioned curable component, since a polarizing plate having a small dimensional change can be produced, it is possible to easily cope with an increase in size of the polarizing plate, and it is possible to suppress production cost from the viewpoint of yield and number. Further, since the polarizing plate obtained in the present invention has good dimensional stability, it is possible to suppress the occurrence of flare in the image display device due to external heat of the backlight.

In the polarizing plate of the present invention, a transparent protective film is provided on at least one surface of the polarizer via the adhesive layer, and an active energy ray-curable adhesive is used in forming the adhesive layer. The active energy ray-curable adhesive contains at least one curable component.

The curable component used in the active energy ray-curable adhesive is selected such that the Tg of the adhesive layer formed therefrom is 60 ° C or higher. From the viewpoint of durability, the Tg of the above-mentioned adhesive layer is more preferably 70 ° C or more, further preferably 75 ° C or more, more preferably 100 ° C or more, and particularly preferably 120 ° C or more. On the other hand, when the Tg of the adhesive layer is too high, the flexibility of the polarizing plate is lowered. Therefore, it is preferred that the Tg of the adhesive layer is 300 ° C or less, more preferably 240 ° C or less, and still more preferably. It is below 180 °C.

Examples of the curable component include a compound having a (meth)acryl fluorenyl group and a compound having a vinyl group. As the curable component, either monofunctional or difunctional or more can be used. One or more of these curable components may be used or two or more types may be used in combination, in which the Tg of the adhesive layer formed of the curable component is 60° C. or higher. As such a curable component, a compound having a (meth) acrylonitrile group is preferred. As the compound having a (meth) acrylonitrile group, it is preferred to use an N-substituted amide group monomer. These monomers are preferred in terms of adhesion. Further, the (meth) acrylonitrile group means an acryl fluorenyl group and/or a methacryl fluorenyl group. In the present invention, the meaning of (meth) is the same as described above.

The N-substituted amide-based monomer is represented by the formula (1): CH ₂ =C(R ¹ )-CONR ² (R ³ ) (R ¹ represents a hydrogen atom or a methyl group, and R ² represents a hydrogen atom or may have a hydroxyl group, The fluorenyl group, the amine group or the quaternary ammonium group has a linear or branched alkyl group having 1 to 4 carbon atoms, and R ³ represents a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. However, R ² and R ^{3 are} not included in the case of a hydrogen atom, or R ² and R ^{3 are} bonded to form a 5-membered ring or a 6-membered ring which may contain an oxygen atom. The linear or branched alkyl group having 1 to 4 carbon atoms in R ² or R ³ in the above formula (1) may, for example, be a methyl group, an ethyl group, an isopropyl group or a t-butyl group. Examples of the alkyl group of the hydroxyl group include a methylol group and a hydroxyethyl group, and examples of the alkyl group having an amine group include an amine methyl group and an amine ethyl group. Further, when R ² and R ^{3 are} bonded to each other to form a 5-membered ring or a 6-membered ring which may contain an oxygen atom, a nitrogen-containing heterocyclic ring is provided. Examples of the heterocyclic ring include a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring.

Specific examples of the N-substituted amide-based monomer include N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-di. Ethyl (meth) acrylamide, N-isopropyl acrylamide, N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-hydroxymethyl (methyl ) acrylamide, N-hydroxyethyl (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, amine methyl (meth) acrylamide, amine ethyl ( Methyl) acrylamide, hydrazine methyl (meth) acrylamide, decyl ethyl (meth) acrylamide, and the like. Further, examples of the heterocyclic ring-containing monomer having a hetero ring include N-propylene decylmorpholine, N-propenylhydrazine piperidine, N-methylpropenyl piperidine, and N-propenylpyridrolidine. These N-substituted amide-based monomers may be used alone or in combination of two or more.

Preferably, the N-substituted amide-based monomer is N-hydroxyethyl acrylamide, N-methylol acrylamide, N-isopropyl acrylamide, and N-propenyl morpholine. N-substituted amide-based monomers also exhibit good adhesion to polarizers with low water content and transparent protective films using materials with low moisture permeability, but the above-exemplified monomers exhibit particularly good adhesion. . Among them, preferred is N-hydroxyethyl acrylamide.

The N-substituted amide-based monomers may be used alone or in combination of two or more. When two or more kinds are used in combination, N-hydroxyethyl propylene oxime is preferred from the viewpoint of durability and adhesion. A combination of an amine and N-propylene decylmorpholine. Further, in the case of the combination, when the ratio of N-hydroxyethyl acrylamide to the total amount of N-hydroxyethyl acrylamide and N-propylene decylmorpholine is 40% by weight or more, it is advantageous to obtain Good adhesion. The above ratio is more preferably 40 to 90% by weight, further preferably 60 to 90% by weight.

In addition to the above, the curable component may, for example, be a compound having an acryl oxime group, and examples thereof include various epoxy (meth) acrylates, (meth) acrylate urethanes, and polyesters (A). Acrylate or various (meth) acrylate monomers and the like. Among them, it is preferred to use an epoxy (meth) acrylate, and it is particularly preferred to use an aromatic ring and A monofunctional (meth) acrylate of a hydroxyl group. When the curable component is not capable of forming an adhesive layer having a Tg of 60 ° C or more, it can be used in combination with the above N-substituted amide-based monomer.

As the monofunctional (meth) acrylate having an aromatic ring and a hydroxyl group, various monofunctional (meth) acrylates having an aromatic ring and a hydroxyl group can be used. The hydroxyl group may be present as a substituent of the aromatic ring, but in the present invention, it is preferably an organic group which bonds the aromatic ring to the (meth) acrylate (the group bonded to the hydrocarbon group, particularly the alkyl group) ) exists.

The monofunctional (meth) acrylate having an aromatic ring and a hydroxyl group may, for example, be a reaction product of a monofunctional epoxy compound having an aromatic ring and (meth)acrylic acid. Examples of the monofunctional epoxy compound having an aromatic ring include phenyl glycidyl ether, tert-butylphenyl glycidyl ether, and phenyl polyethylene glycol glycidyl ether. Specific examples of the monofunctional (meth) acrylate having an aromatic ring and a hydroxyl group include, for example, 2-hydroxy-3-phenoxypropyl (meth) acrylate and 2-hydroxy-3-t-butyl group. Phenoxypropyl (meth) acrylate, 2-hydroxy-3-phenyl polyethylene glycol propyl (meth) acrylate, and the like.

Further, examples of the compound having a (meth) acrylonitrile group include a carboxyl group. Carboxyl monomers are also preferred in terms of adhesion. Examples of the carboxyl group monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate. Among them, acrylic acid is preferred.

In addition to the above, examples of the compound having a (meth)acryl fluorenyl group include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and (meth)acrylic acid 2- a (meth)acrylic acid alkyl ester having 1 to 12 carbon atoms such as ethylhexyl ester, isooctyl (meth)acrylate, isodecyl (meth)acrylate or lauryl (meth)acrylate; (meth)ethyl methacrylate, (meth)acrylic acid alkoxyalkyl monomer; (meth)acrylic acid 2-hydroxyethyl, (meth)acrylic acid 2-hydroxypropyl ester, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, a hydroxyl group-containing monomer such as 12-hydroxylauryl (meth)acrylate or (4-hydroxymethylcyclohexyl)-methacrylate; an acid anhydride group-containing monomer such as maleic anhydride or itaconic anhydride; and caprolactone of acrylic acid Adduct; styrene sulfonic acid or allyl sulfonic acid, 2-(A Sulfhydrylamine-2-methylpropanesulfonic acid, (meth)acrylamidamine propanesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloxynaphthalenesulfonic acid, etc. a monomer; a phosphate group-containing monomer such as 2-hydroxyethyl acryloyl phosphate. Further, (meth)acrylamide; maleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc.; aminoethyl (meth)acrylate, Aminopropyl (meth) acrylate, N,N-dimethylaminoethyl (meth) acrylate, tert-butylaminoethyl (meth) acrylate, 3-(3-pyridyl) propyl An alkylaminoalkyl (meth) acrylate monomer such as a (meth) acrylate; N-(methyl) propylene oxymethylene succinimide or N-(methyl) acrylonitrile A nitrogen-containing monomer such as a succinimide-based monomer such as -6-oxyhexamethylene succinimide or N-(methyl) propylene decyl-8-oxy octamethylene succinimide.

As described above, as the curable component in the active energy ray-curable adhesive, it is preferred to use an N-substituted amide-based monomer alone or a combination of an N-substituted amide-based monomer and a monomer having an aromatic ring and a hydroxyl group. Functional (meth) acrylate. When these are used in combination, it is preferred to set the ratio of the N-substituted amide-based monomer to 40% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, and further preferably. It is 70% by weight or more, and particularly preferably 80% by weight or more.

As the curable component, a difunctional or higher curable component can be used. The difunctional or higher curable component is preferably a difunctional or higher (meth) acrylate, and particularly preferably a difunctional or higher epoxy (meth) acrylate. The difunctional or higher epoxy group (meth) acrylate is obtained by reacting a polyfunctional epoxy compound with (meth)acrylic acid. The polyfunctional epoxy compound can be exemplified by various methods. Examples of the polyfunctional epoxy compound include an aromatic epoxy resin, an alicyclic epoxy resin, and an aliphatic epoxy resin.

Examples of the aromatic epoxy resin include bisglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, bisphenol epoxy resin such as bisglycidyl ether of bisphenol S; and phenol novolac epoxy Resin, cresol novolak epoxy resin, phenol novolak resin such as hydroxybenzaldehyde phenol novolac resin; glycidyl ether of tetrahydroxyphenylmethane, four A polyfunctional epoxy resin such as glycidyl ether of hydroxybenzophenone or epoxidized polyethylene phenol.

Examples of the alicyclic epoxy resin include a hydride of the above aromatic epoxy resin, a cyclohexane type, a cyclohexyl methyl ester type, a dicyclohexyl methyl ether type, a spiro ring type, and a tricyclodecane type epoxy resin. .

The aliphatic epoxy resin may, for example, be a polyglycidyl ether of an aliphatic polyol or an alkylene oxide adduct thereof. Examples of these include diglycidyl ether of 1,4-butanediol, diglycidyl ether of 1,6-hexanediol, triglycidyl ether of glycerol, and triglycidyl ether of trimethylolpropane. Adding one or more alkylene oxides (ethylene oxide) to diglycidyl ether of polyethylene glycol, diglycidyl ether of propylene glycol, aliphatic polyol such as ethylene glycol, propylene glycol or glycerin Polyglycidyl ether of a polyether polyol obtained by propylene oxide or the like.

The epoxy equivalent of the above epoxy resin is usually from 30 to 3,000 g/equivalent, preferably from 50 to 1,500 g/equivalent.

The above-mentioned difunctional or higher epoxy (meth) acrylate is preferably an epoxy (meth) acrylate of an aliphatic epoxy resin, and particularly preferably an epoxy (methyl) of a difunctional aliphatic epoxy resin. )Acrylate.

The active energy ray-curable adhesive of the present invention contains a curable component, and an optional additive may be added as needed in addition to the above components. The active energy ray-curable adhesive can be used in the form of an electron beam hardening type or an ultraviolet curing type. When the above-mentioned adhesive is used in the electron beam curing type, the polymerization initiator is not particularly required to be contained in the above-mentioned adhesive, but when it is used in the ultraviolet curing type, a photopolymerization initiator is used. The photopolymerization initiator is used in an amount of usually 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight per 100 parts by weight of the curable component.

Further, examples of the additive include a sensitizer represented by a carbonyl compound for improving the curing speed or sensitivity at the time of using an electron ray; an adhesion promoter represented by a decane coupling agent or ethylene oxide; and improvement and transparency protection. Additive for film wettability; An additive that enhances mechanical strength or processability, such as a base compound or a hydrocarbon (natural, synthetic resin); ultraviolet absorber, anti-aging agent, dye, processing aid, ion trapping agent, antioxidant, tackifier, Filler (except metal compound filler), plasticizer, leveling agent, anti-foaming agent, antistatic agent, and the like.

The polarizer is formed of a polyvinyl alcohol-based resin. As the polarizer, a polyvinyl alcohol resin film may be dyed with a dichroic material (typically iodine or a dichroic dye) and uniaxially stretched. The degree of polymerization of the polyvinyl alcohol-based resin constituting the polyvinyl alcohol-based resin film is preferably from 100 to 5,000, more preferably from 1,400 to 4,000. When the degree of polymerization is too low, elongation fracture tends to occur when a specific elongation is performed, and when the degree of polymerization is too high, tension is required to be abnormal when stretching, and mechanical elongation may not be possible.

The polyvinyl alcohol-based resin film constituting the polarizer can be formed by any appropriate method (for example, a casting method in which a resin is dissolved in water or an organic solvent, and a casting method, a casting method, or an extrusion method). The thickness of the polarizer can be appropriately set depending on the purpose or use of the LCD using the polarizing plate, and is usually about 5 to 80 μm.

The method for producing the polarizer can be any appropriate method depending on the purpose, materials used, conditions, and the like. For example, the polyvinyl alcohol-based resin film may be applied to a series of manufacturing steps which usually include a step of swelling, dyeing, crosslinking, stretching, washing, and drying. In each step of the removal drying step, the polyvinyl alcohol-based resin film is immersed in the liquid containing the solution used in each step to carry out the treatment. The order, the number of times, and the presence or absence of each treatment of swelling, dyeing, cross-linking, stretching, washing, and drying can be appropriately set depending on the purpose, materials, conditions, and the like. For example, several treatments can be performed simultaneously in one step, and the swelling treatment, the dyeing treatment, and the crosslinking treatment can be simultaneously performed. Further, it is preferable to carry out the crosslinking treatment before and after the stretching treatment, for example. Further, for example, the water washing treatment may be performed after completion of all the treatments, or may be performed only after the specific treatment.

The swelling step is typically carried out by immersing the polyvinyl alcohol resin film in a water-filled treatment bath. By performing this process, it is possible to clean the polyethylene The soil or the anti-caking agent on the surface of the enol-based resin film can prevent unevenness in dyeing unevenness by swelling the polyvinyl alcohol-based resin film. In the swelling bath, glycerin or potassium iodide is added as appropriate. The temperature of the swelling bath is usually about 20 to 60 ° C, and the time of immersion in the swelling bath is usually about 0.1 to 10 minutes.

The dyeing step is typically carried out by immersing the polyvinyl alcohol resin film in a treatment bath containing a dichroic material such as iodine. The solvent used for the dye bath solution is usually water, and an organic solvent compatible with water may be added in an appropriate amount. The dichroic substance is usually used in a ratio of 0.1 to 1 part by weight based on 100 parts by weight of the solvent. When iodine is used as the dichroic substance, the dye bath solution preferably contains an auxiliary such as an iodide. The reason for this is to improve the dyeing efficiency. The auxiliary agent is used in a proportion of preferably 0.02 to 20 parts by weight, more preferably 2 to 10 parts by weight, per 100 parts by weight of the solvent. Specific examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Wait. The temperature of the dye bath is usually about 20 to 70 ° C, and the time of immersion in the dye bath is usually about 1 to 20 minutes.

The crosslinking step is typically carried out by immersing the dyed polyvinyl alcohol resin film in a treatment bath containing a crosslinking agent. The crosslinking agent can be any suitable crosslinking agent. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These may be used singly or in combination. The solvent used for the crosslinking bath solution is usually water, and an organic solvent compatible with water may be added in an appropriate amount. The crosslinking agent is used in a proportion of 1 to 10 parts by weight based on 100 parts by weight of the solvent. When the concentration of the crosslinking agent is less than 1 part by weight, sufficient optical characteristics cannot be obtained. When the concentration of the crosslinking agent exceeds 10 parts by weight, the stress generated in the film during stretching becomes large, and the obtained polarizing plate may shrink. The crosslinking bath solution preferably further contains an auxiliary such as an iodide. The reason for this is that it is easy to obtain uniform characteristics in the plane. The concentration of the auxiliary agent is preferably from 0.05 to 15% by weight, further preferably from 0.5 to 8% by weight. Specific examples of iodide, and dyeing The same is true for the steps. The temperature of the crosslinking bath is usually about 20 to 70 ° C, preferably about 40 to 60 ° C. The time of immersion in the crosslinking bath is usually from 1 second to 15 seconds, preferably from 5 seconds to 10 minutes.

The extension step can also be carried out in any stage as described above. Specifically, it can be carried out after the dyeing treatment, or before the dyeing treatment, and can be carried out simultaneously with the swelling treatment, the dyeing treatment, and the crosslinking treatment, or after the dyeing treatment. The cumulative stretching ratio of the polyvinyl alcohol-based resin film is usually 5 times or more, preferably 5 to 7 times, and more preferably 5 to 6.5 times. When the cumulative stretching ratio is less than 5 times, it is difficult to obtain a polarizing plate having a high degree of polarization. When the cumulative stretching ratio exceeds 7 times, the polyvinyl alcohol-based resin film may be easily broken. Any suitable method can be employed as a specific method of extension. For example, when the wet stretching method is employed, the polyvinyl alcohol-based resin film is stretched to a specific multiple in the treatment bath. As the stretching bath solution, a solution in which a compound of various metal salts, iodine, boron or zinc is added is preferably used in a solvent such as water or an organic solvent such as ethanol.

The water washing step is typically carried out by immersing the polyvinyl alcohol-based resin film subjected to the above various treatments in a treatment bath. The excess residue on the polyvinyl alcohol-based resin film can be washed away by the water washing step. The water bath may be pure water or an aqueous solution of an iodide (for example, potassium iodide, sodium iodide, etc.). The concentration of the aqueous iodide solution is preferably from 0.1 to 10% by weight. Additives such as zinc sulfate and zinc chloride may also be added to the aqueous iodide solution. The temperature of the water bath is preferably 10 to 60 ° C, and further preferably 30 to 40 ° C. The immersion time is from 1 second to 1 minute. The washing step can be carried out only once, or as many times as necessary. When it is carried out a plurality of times, the kind or concentration of the additive contained in the water bath for each treatment can be appropriately adjusted. For example, the water washing step includes a step of immersing the polyvinyl alcohol-based resin film subjected to the above various treatments in a potassium iodide aqueous solution (0.1 to 10% by weight, 10 to 60 ° C) for about 1 second to 1 minute, and washing with pure water. step. Further, in the water washing step, in order to improve the surface modification of the polarizer or the drying efficiency of the polarizer, an organic solvent (such as ethanol) which is compatible with water may be added in an appropriate amount.

The drying step can be carried out by any suitable method (for example, natural drying, blast drying, and heat drying). For example, the drying temperature during heating and drying is usually about 20 to 80 ° C, and the drying time is usually about 1 to 10 minutes. A polarizer can be obtained in the above manner.

The moisture content of the polarizer used in the present invention is preferably 20% by weight or less, more preferably 0 to 15% by weight or less, still more preferably 1 to 15% by weight or less. When the water content is more than 20% by weight, there is a possibility that the dimensional change of the obtained polarizing plate is large, so that the dimensional change in a high-temperature or high-temperature high-humidity environment is large.

The moisture content of the polarizer of the present invention can be adjusted by any appropriate method. For example, a method of controlling by adjusting the conditions of the drying step in the manufacturing steps of the polarizer can be mentioned.

The moisture content of the polarizer can be determined by the following method. That is, the polarizer was cut into a size of 100 × 100 mm, and the initial weight of the sample was measured. Next, the sample was dried at 120 ° C for 2 hours, and the weight after drying was measured, and the water content was measured according to the following formula. Water content (% by weight) = {(initial weight - weight after drying) / initial weight} x 100. The weight was measured three times and the average value was taken.

As the material constituting the transparent protective film, for example, a thermoplastic resin film excellent in transparency, mechanical strength, thermal stability, water repellency, isotropy, and the like is used. Specific examples of such a thermoplastic resin include cellulose resins such as triethylsulfonyl cellulose, polyester resins, polyether oxime resins, polyfluorene resins, polycarbonate resins, polyamide resins, and polyimine. A resin, a polyolefin resin, a (meth)acrylic resin, a cyclic polyolefin resin (norbornene-based resin), a polyarylate resin, a polystyrene resin, a polyvinyl alcohol resin, and a mixture thereof. Further, on one side of the polarizing plate, a transparent protective film is adhered via an adhesive layer, and on the other side, a (meth)acrylic, urethane-based or urethane-based urethane-based system can be used. A thermosetting resin such as an epoxy-based or polyfluorene-based resin or an ultraviolet curable resin is used as a transparent protective film. One or more optional additives may be contained in the transparent protective film. Examples of the additive include a UV absorber, an antioxidant, a lubricant, a plasticizer, and a release agent. Molding agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the above thermoplastic resin in the transparent protective film is preferably from 50 to 100% by weight, more preferably from 50 to 99% by weight, further preferably from 60 to 98% by weight, particularly preferably from 70 to 97% by weight. percentage. When the content of the above-mentioned thermoplastic resin in the transparent protective film is 50% by weight or less, the high transparency and the like which the thermoplastic resin originally has may not be sufficiently exhibited.

Further, the transparent protective film may, for example, be a polymer film described in JP-A-2001-343529 (WO 01/37007); for example, it contains a substituted and/or unsubstituted quinone imine group in the side chain (A). The thermoplastic resin and the resin composition of the thermoplastic resin having a substituted and/or unsubstituted phenyl group and a nitro group in the side chain of (B). Specific examples include an alternating copolymer of isobutylene and N-methylmaleimide and acrylonitrile. A film of a resin composition of a styrene copolymer. As the film, a film formed of a mixed extrusion of a resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic modulus, it is possible to eliminate problems such as flare caused by distortion of the polarizing plate, and it is excellent in humidifying durability because the moisture permeability is small.

The thickness of the transparent protective film can be appropriately determined, but it is usually about 1 to 500 μm, particularly preferably about 1 to 300 μm, more preferably 5 to 200 μm, in terms of workability and thinness such as strength and workability. about. The transparent protective film is particularly preferably used in a thickness of 5 to 150 μm.

Further, when a transparent protective film is provided on both sides of the polarizer, a protective film formed of the same polymer material may be used on the front and back sides, and a protective film formed of a different polymer material or the like may be used.

The transparent protective film of the present invention preferably uses at least one selected from the group consisting of a cellulose resin, a polycarbonate resin, a cyclic polyolefin resin, and a (meth)acrylic resin. The adhesive for an electron beam hardening type polarizing plate of the present invention exhibits excellent adhesion to the above various transparent protective films. In particular, the adhesive for an electron beam hardening type polarizing plate of the present invention is difficult The acrylic resin which satisfies the adhesiveness also exhibits good adhesion.

Cellulose resins are esters of cellulose and fatty acids. Specific examples of such a cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Among them, cellulose triacetate is particularly preferred. There are many commercially available products of cellulose triacetate which are advantageous in terms of availability or cost. Examples of commercially available products of cellulose triacetate include the trade names "UV-50", "UV-80", "SH-80", "TD-80U", and "TD-" manufactured by Fujifilm Corporation. TAC", "UZ-TAC" or "KC Series" manufactured by Konica Corporation. In general, the in-plane retardation (Re) of the cellulose triacetate is almost zero, and the thickness direction retardation (Rth) has about ~60 nm.

Further, the cellulose resin film having a small phase difference in the thickness direction can be obtained, for example, by treating the above cellulose resin. For example, a base film such as polyethylene terephthalate, polypropylene, or stainless steel coated with a solvent such as cyclopentanone or methyl ethyl ketone is bonded to a common cellulose film and dried by heating (for example, After heating and drying at 80 to 150 ° C for about 3 to 10 minutes, the substrate film is peeled off, and the norbornene resin or the (meth)acrylic resin is dissolved in cyclopentanone or methyl ethyl ketone. The solution obtained in the solvent is applied onto a common cellulose resin film, and dried by heating (for example, drying at 80 to 150 ° C for about 3 to 10 minutes), followed by a method of peeling off the coating film.

Further, a cellulose resin film having a small degree of phase difference in the thickness direction can be a fatty acid cellulose resin film in which the degree of fat substitution is controlled. In the cellulose triacetate which is usually used, the degree of substitution of acetic acid is about 2.8. It is preferred to control the degree of substitution of acetic acid to 1.8 to 2.7, whereby Rth can be reduced. The Rth is controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide or triethyl citrate to the cellulose-based resin. The amount of the plasticizer added is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, even more preferably 1 to 15 parts by weight, per 100 parts by weight of the fatty acid cellulose-based resin.

As a specific example of the cyclic polyolefin resin, a norbornene-based resin is preferred. ring The polyolefin resin is a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit, and examples thereof include a Japanese Patent Laid-Open No. Hei No. 1-240517, a Japanese Patent Laid-Open No. Hei No. Hei No. Hei No. Hei. The resin described in the publication No. 122137 or the like. Specific examples thereof include a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a copolymer of a cyclic olefin and an α-olefin such as ethylene or propylene (typically a random copolymer) And a random polymer modified with an unsaturated carboxylic acid or a derivative thereof, and the like, and the like. Specific examples of the cyclic olefin include a norbornene-based monomer.

There are many kinds of cyclic polyolefin resin commercially available products. Specific examples include "ZEONEX" and "ZEONOR" manufactured by Japan ZEON Co., Ltd., "ARTON" manufactured by JSR AG, "TORVUS" by TICONA, and "APEL" by Mitsui Chemicals Co., Ltd. ".

The (meth)acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C or more, more preferably 120 ° C or more, further preferably 125 ° C or more, and particularly preferably 130 ° C or more. By setting Tg to 115 ° C or more, the heat resistance of the polarizing plate is excellent. The upper limit of the Tg of the (meth)acrylic resin is not particularly limited, but is preferably 170 ° C or less from the viewpoint of moldability. A film having an in-plane retardation (Re) and a thickness direction retardation (Rth) of almost zero can be formed from a (meth)acrylic resin.

As the (meth)acrylic resin, any suitable (meth)acrylic resin can be employed within the range not impairing the effects of the present invention. For example, poly(meth)acrylate such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth) acrylate copolymer, methyl group Methyl acrylate-acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-A) A cyclohexyl acrylate copolymer, a methyl methacrylate-norbornene (meth) acrylate copolymer, etc.). Preferably, a poly(meth)acrylic acid C1-6 alkyl ester such as poly(methyl) acrylate is used. More preferably, methyl methacrylate is the main component (50 to 100% by weight, preferably 70 to 100% by weight of methyl methacrylate resin.

Specific examples of the (meth)acrylic resin include, for example, ACRYPET VH or ACRYPET VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and a ring structure in the molecule described in JP-A-2004-70296. An acrylic resin, a high Tg (meth)acrylic resin obtained by intramolecular crosslinking or intramolecular cyclization.

As the (meth)acrylic resin, a (meth)acrylic resin having a lactone ring structure can also be used. The reason for this is that it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

Examples of the (meth)acrylic resin having a lactone ring structure include JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, and JP-A. A (meth)acrylic resin having a lactone ring structure described in JP-A-2005-146084, and the like.

The (meth)acrylic resin having a lactone ring structure preferably has a cyclic structure represented by the following formula (Chemical Formula 1).

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Further, the organic residue may also contain an oxygen atom.

The content of the lactone ring structure represented by the formula (Chemical Formula 1) in the structure of the (meth)acrylic resin having a lactone ring structure is preferably from 5 to 90% by weight, more preferably from 10 to 70. The weight percentage is further preferably 10 to 60% by weight, particularly preferably 10 to 50% by weight. When the content of the lactone ring structure represented by the formula (Chemical Formula 1) in the structure of the (meth)acrylic resin having a lactone ring structure is less than 5 weight%, resistance is obtained. Heat, solvent resistance, and surface hardness may be insufficient. When the content ratio of the lactone ring structure represented by the formula (Chemical Formula 1) in the structure of the (meth)acrylic resin having a lactone ring structure is more than 90% by weight, there is a possibility that the formability is insufficient.

The mass average molecular weight of the (meth)acrylic resin having a lactone ring structure is preferably from 1,000 to 2,000,000, more preferably from 5,000 to 1,000,000, further preferably from 1,000 to 500,000, particularly preferably from 50,000 to 500,000. When the mass average molecular weight deviates from the above range, it is considered from the viewpoint of mold processability.

The (meth)acrylic resin having a lactone ring structure preferably has a Tg of 115 ° C or higher, more preferably 120 ° C or higher, further preferably 125 ° C or higher, and particularly preferably 130 ° C or higher. Since the Tg is 115° C. or higher, for example, when a polarizing plate is incorporated as a transparent protective film, it is a transparent protective film excellent in durability. The upper limit of the Tg of the (meth)acrylic resin having a lactone ring structure is not particularly limited, and is preferably 170 ° C from the viewpoint of moldability and the like.

A (meth)acrylic resin having a lactone ring structure, a molded article obtained by injection molding, and a total permeability measured by an ASTM (American Society for Testing and Materials)-D-1003 method The higher the light rate, the better, preferably 85% or more, more preferably 88% or more, further preferably 90% or more. The total light transmittance is the basis of transparency, and when the total light transmittance is less than 85%, transparency may be lowered.

The transparent protective film is generally a transparent protective film having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm. The front phase difference Re is represented by Re = (nx - ny) × d. The thickness direction phase difference Rth is represented by Rth = (nx - nz) × d. Further, the Nz coefficient is expressed by Nz = (nx - nz) / (nx - ny). [The refractive index in the slow axis direction, the fast axis direction, and the thickness direction of the film is set to nx, ny, nz, and d (nm), respectively, to the film thickness. The direction of the slow axis is the direction in which the refractive index in the film plane is the largest]. Further, it is preferred that the transparent protective film be as colored as possible. It is preferable to use a transparent protective film having a phase difference in the thickness direction of -90 nm to +75 nm, which can be transparently protected by using such a retardation value (Rth) of -90 nm to +75 nm. The film substantially eliminates the coloring of the polarizing plate (optical coloring) caused by the transparent protective film. The phase difference (Rth) in the thickness direction is further preferably -80 nm to +60 nm, particularly preferably -70 nm to +45 nm.

On the other hand, as the transparent protective film, a phase difference plate having a front phase difference of 40 nm or more and/or a phase difference in the thickness direction of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the phase difference in the thickness direction is usually controlled to be in the range of 80 to 300 nm. When a retardation film is used as the transparent protective film, the retardation film also functions as a transparent protective film, so that the thickness can be reduced.

Examples of the retardation film include a birefringent film obtained by subjecting a polymer material to uniaxial or biaxial stretching treatment, an alignment film of a liquid crystal polymer, and an alignment layer supporting a liquid crystal polymer by a film. The thickness of the phase difference plate is also not particularly limited, and is usually about 20 to 150 μm.

Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, and polycarbonic acid. Ester, polyarylate, polyfluorene, polyethylene terephthalate, polyethylene naphthalate, polyether oxime, polyphenylene sulfide, polyphenylene ether, polyaryl fluorene, polyamine, poly Yttrium, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin) or these binary, ternary copolymers, graft copolymers, blends Wait. These polymer materials become an alignment material (stretching film) by stretching or the like.

The liquid crystal polymer may, for example, be a main chain type or a side chain type liquid crystal polymer in which a linear atomic group (liquid crystal element) which imparts a conjugate property of liquid crystal alignment property is introduced into a main chain or a side chain of a polymer. . Specific examples of the main chain type liquid crystal polymer include a structure in which a liquid crystal nucleus is bonded to a space portion to which flexibility is imparted, for example, a nematic alignment type polyester liquid crystal polymer, a disk type polymer, or a cholesterol type. Polymers, etc. Specific examples of the side chain type liquid crystal polymer include polydecane, polyacrylate, polymethacrylate or polymalonate as a main chain skeleton, and are formed as a side chain by a conjugated atomic group. a spacer of the liquid crystal source formed by the para-substituted cyclic compound unit imparting nematic alignment Compounds, etc. These liquid crystal polymers are carried out, for example, by a method of rubbing a surface of a film such as polyimide or polyvinyl alcohol formed on a glass plate, and a film in which a cerium oxide is vapor-deposited. A solution of the liquid crystalline polymer is developed on the alignment treatment surface and heat-treated.

The phase difference plate may have an appropriate phase difference depending on, for example, the purpose of compensating for coloring or viewing angle due to birefringence of various wavelength plates or liquid crystal layers, or may be formed by stacking two or more kinds of phase difference plates to control the phase difference. Such as optical characteristics, etc.

The phase difference plate can be selected and used according to various uses to satisfy nx=ny>nz, nx>ny>nz, nx>ny=nz, nx>nz>ny, nz=nx>ny, nz>nx>ny, nz>nx =ny relationship. Furthermore, ny=nz includes not only the case where ny and nz are identical, but also the case where ny and nz are substantially the same.

For example, in a phase difference plate satisfying nx>ny>nz, it is preferable to use a front phase difference of 40 to 100 nm, a thickness direction phase difference of 100 to 320 nm, and an Nz coefficient of 1.8 to 4.5. For example, in a phase difference plate (positive A plate) satisfying nx>ny=nz, it is preferable to use a phase difference plate whose front phase difference satisfies 100 to 200 nm. For example, in a phase difference plate (negative A plate) satisfying nz=nx>ny, it is preferable to use a phase difference plate whose front phase difference satisfies 100 to 200 nm. For example, in a phase difference plate satisfying nx>nz>ny, it is preferable to use a phase difference plate whose front phase difference satisfies 150 to 300 nm and whose Nz coefficient satisfies more than 0 to 0.7. Further, as described above, for example, one satisfying nx=ny>nz, nz>nx>ny, or nz>nx=ny can be used.

The transparent protective film can be appropriately selected according to a suitable liquid crystal display device. For example, in the case of VA (Vertical Alignment), including MVA (Multi-domain Vertical Alignment) and PVA (Patterned Vertical Alignment), it is preferable that at least the polarizing plate is The transparent protective film on one side (unit side) has a phase difference. As a specific phase difference, a range of Re=0 to 240 nm and Rth=0 to 500 nm is preferable. If the three-dimensional refractive index is used, Good is the case of nx>ny=nz, nx>ny>nz, nx>nz>ny, nx=ny>nz (single-axis, dual-axis, negative C-plate). When the polarizing plate is used above and below the liquid crystal cell, the transparent protective film having a phase difference or a top or lower of the liquid crystal cell may have a phase difference.

For example, in the case of IPS (In-Plane Switching), including FFS (Fringe Field Switching), the transparent film on the side of the polarizing plate may have a phase difference or may have no phase difference. For example, in the case where there is no phase difference, it is preferable to have no phase difference above and below the liquid crystal cell. When there is a phase difference, it is preferable to have a phase difference between the upper and lower sides of the liquid crystal cell, and a case where there is a phase difference between the upper and lower sides (for example, the upper side is Z-formed, the lower side has no phase difference, or The upper side is the A plate and the lower side is the positive C plate). In the case of a phase difference, a range of Re = -500 to 500 nm and Rth = -500 to 500 nm is preferable. If the three-dimensional refractive index is used, it is preferable that nx>ny=nz, nx>nz>ny, nz>nx=ny, nz>nx>ny (single-axis, Z-, positive C-plate, positive A-plate) ).

Further, the film having the retardation may be bonded to a transparent protective film having no phase difference to impart the above function.

The polarizer or the transparent protective film may be subjected to surface modification treatment before the application of the above-mentioned adhesive. Specific examples of the treatment include corona treatment, plasma treatment, bottom treatment, saponification treatment, and coupling agent treatment.

It is also possible to apply a hard coat layer, an anti-reflection treatment, or a treatment for preventing sticking, non-diffusion or anti-glare to the surface of the transparent protective film which is not followed by the polarizer.

In order to prevent the surface of the polarizing plate from being damaged or the like, the hard coating treatment may be performed by, for example, adding a hardened film having excellent hardness or sliding properties such as an acrylic or an ketone-based resin to a transparent ultraviolet curable resin. A hard coat layer is formed by protecting the surface of the film or the like. The antireflection treatment is performed to prevent the surface of the polarizing plate from reflecting external light, and can be realized by formation of a conventional antireflection film or the like. Further, the anti-adhesive treatment is carried out in order to prevent adhesion to an adjacent layer (for example, a diffusion plate on the backlight side).

Further, the purpose of performing the anti-glare treatment is to prevent external light from being reflected on the surface of the polarizing plate and to interfere with the visibility of the transmitted light of the polarizing plate, for example, by roughing the surface by blasting or imprinting, and by arranging transparent particles. In a suitable manner, a fine concavo-convex structure is formed on the surface of the transparent protective film. As the fine particles contained in the formation of the surface fine uneven structure, for example, cerium oxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, or oxidation having an average particle diameter of 0.5 to 20 μm can be used. Inorganic fine particles having conductivity, such as ruthenium, and transparent fine particles such as organic fine particles containing a crosslinked or uncrosslinked polymer. When the surface fine uneven structure is formed, the amount of the fine particles used is usually from 2 to 70 parts by weight, preferably from 5 to 50 parts by weight, per 100 parts by weight of the transparent resin forming the surface fine uneven structure. The anti-glare layer may have a diffusion layer (viewing angle expansion function or the like) that diffuses transmitted light by the polarizing plate to expand the viewing angle or the like.

Further, the antireflection layer, the anti-adhesion layer, the diffusion layer, the antiglare layer, and the like may be provided on the transparent protective film itself, or may be separately provided as an optical layer on a film different from the transparent protective film.

The polarizing plate of the present invention is produced by bonding a transparent protective film and a polarizer using the above-mentioned adhesive. The manufacturing method includes the step of applying the adhesive to a surface of the polarizer having the surface of the adhesive layer and/or a surface of the transparent protective film on which the adhesive layer is formed; and passing the polarizer and the transparent protective film a step of bonding the polarizing plate with an adhesive; and a step of forming an adhesive layer by irradiating an active energy ray (electron ray, ultraviolet ray, or the like) to the polarizing plate and the transparent protective film which are bonded together by the adhesive for the polarizing plate .

The coating method of the subsequent agent can be appropriately selected depending on the viscosity of the adhesive or the target thickness. Examples of the coating method include a reverse coater, a gravure coater (orientation, reverse or lithography), a bar coater, a roll coater, a die coater, and a bar coater. , bar coater, etc. Further, at the time of coating, a dip coating method or the like can be suitably used.

The polarizer and the transparent protective film are bonded via an adhesive applied in the above manner. The bonding of the polarizer to the transparent protective film can be performed by a roll bonding machine or the like.

After bonding the polarizer and the transparent protective film, an active energy ray (electron ray, ultraviolet ray, etc.) is irradiated to harden the adhesive. The irradiation direction of the active energy ray (electron ray, ultraviolet ray, etc.) can be irradiated from any suitable direction. It is preferred to irradiate from the side of the transparent protective film. When irradiated from the side of the polarizer, the polarizer may be deteriorated by an active energy ray (electron rays, ultraviolet rays, or the like).

The active energy ray-curable adhesive is preferably used as an electron beam curing type adhesive. The irradiation conditions of the electron beam may be any suitable conditions as long as the conditions for curing the above-mentioned adhesive are used. For example, when electron beam irradiation is performed, the acceleration voltage is preferably 5 kV to 300 kV, and further preferably 10 kV to 250 kV. When the accelerating voltage is lower than 5kV, the electron beam may not reach the adhesive and cause insufficient hardening. When the accelerating voltage exceeds 300kV, the penetration of the sample is too strong, and the electron beam is reflected, possibly against a transparent protective film or polarizer. Bring damage. The amount of the irradiation line is 5 to 100 kGy, and more preferably 10 to 75 kGy. When the amount of the irradiation line is less than 5 kGy, the adhesive hardening is insufficient, and when it exceeds 100 kGy, the transparent protective film or the polarizer is damaged, and mechanical strength is lowered or yellowed, and specific optical characteristics are not obtained.

When curing by ultraviolet irradiation, the polymerization initiator is formulated in an amount of 0.1 to 5 parts by weight, preferably 1 to 4 parts by weight, more preferably 2 to 3 parts by weight, per 100 parts by weight of the curable component. The ultraviolet irradiation conditions may be any suitable conditions as long as the conditions of the above-mentioned adhesive can be cured. The amount of ultraviolet light irradiation is preferably from 100 to 500 mJ, and further preferably from 200 to 400 mJ.

The thickness of the adhesive layer in the polarizing plate of the present invention obtained in the above manner is 0.01 to 7 μm. It is preferably 0.01 to 5 μm, more preferably 0.01 to 2 μm, further preferably 0.01 to 1 μm. When the above thickness is less than 0.01 μm, the cohesive force of the adhesion force itself may not be obtained, and the adhesion strength may not be obtained. When the thickness of the adhesive layer exceeds 7 μm, the polarizing plate Unable to meet durability.

Further, the adhesive layer has a gel fraction of 50% by weight or more, which is preferable in terms of durability. The gel fraction is preferably 60% by weight or more, and more preferably 70% by weight or more. Further, the gel fraction was measured by the method described in the examples.

The electron beam irradiation is usually carried out in an inert gas, but may be carried out in the atmosphere or with a small amount of oxygen if necessary. Depending on the material of the transparent protective film, it is possible to generate an oxygen suppression effect on the surface of the transparent protective film which is initially irradiated by the electron beam by introducing a small amount of oxygen, thereby preventing damage to the transparent protective film, and effectively irradiating only the adhesive. Electron ray.

When the above-mentioned manufacturing method is carried out on a continuous production line, the linear velocity depends on the hardening time of the adhesive, but is preferably from 1 to 500 m/min, more preferably from 5 to 300 m/min, further preferably from 10 to 100 m/min. . When the linear velocity is too small, the productivity is lacking, or the damage to the transparent protective film is too large, and a polarizing plate capable of withstanding the durability test cannot be produced. When the linear velocity is too large, the curing of the adhesive is insufficient, and the target adhesion is sometimes not obtained.

The polarizing plate of the present invention can be used as an optical film laminated with other optical layers in actual use. The optical layer is not particularly limited, and one or two or more layers such as a reflecting plate or a semi-transmissive plate, a phase difference plate (including a 1/2 or 1/4 wavelength plate), and a viewing angle compensation film may be used, which is equal to the liquid crystal display device. The optical layer sometimes used in the formation of the plasma. Particularly preferably, the polarizing plate is a reflective polarizing plate or a semi-transmissive polarizing plate which is formed by laminating a reflecting plate or a transflective plate on the polarizing plate of the present invention; and elliptically polarizing light is formed by laminating a phase difference plate on the polarizing plate. a plate or a circular polarizing plate; a wide viewing angle polarizing plate formed by laminating a viewing angle compensation film on a polarizing plate; or a polarizing plate formed by laminating a brightness improving film on a polarizing plate.

The reflective polarizing plate is formed by providing a reflective layer on a polarizing plate, and can be used to form a liquid crystal display device of a type that reflects incident light from a visual confirmation side (display side), and can omit a built-in backlight or the like. The light source has an advantage that it is easy to reduce the thickness of the liquid crystal display device. When a reflective polarizer is formed, it can be transparently protected as needed The layer is formed in an appropriate manner such as a method in which a reflective layer formed of a metal or the like is attached to one surface of the polarizing plate.

As a specific example of the reflective polarizing plate, for example, a foil or a vapor deposited film formed of a reflective metal such as aluminum may be attached to one surface of the matte transparent protective film to form a reflective layer. In addition, the transparent protective film may be provided with fine particles to form a fine concavo-convex structure, and a reflective layer having a fine concavo-convex structure thereon may be used. The reflective layer of the fine concavo-convex structure diffuses the incident light by diffuse reflection, thereby preventing the directivity or the appearance from being bright, thereby suppressing the advantages of unevenness in brightness and the like. Further, the transparent protective film containing fine particles also has an advantage of diffusing the incident light and the reflected light of the incident light to further suppress the unevenness of light and dark. The formation of the reflective layer of the fine concavo-convex structure reflecting the fine concavo-convex structure on the surface of the transparent protective film can be directly applied to the transparent protection by a vapor deposition method such as a vacuum deposition method, an ion plating method, or a sputtering method, or a plating method. The method of attaching a metal to the surface of the layer is performed.

Instead of directly attaching the reflecting plate to the transparent protective film of the polarizing plate, a reflecting sheet formed by providing a reflecting layer on a suitable film based on the transparent film may be used. Further, since the reflective layer is usually formed of a metal, it is preferable to use a transparent protective film or the like from the viewpoint of preventing a decrease in reflectance due to oxidation, and further maintaining the initial reflectance for a long period of time or avoiding a separate protective layer. A form in which a polarizing plate or the like covers a state of a reflecting surface thereof.

Further, in the above, the semi-transmissive polarizing plate can be obtained by forming a semi-transmissive reflective layer such as a semi-mirror surface through which the reflective layer reflects light and transmits the light. The semi-transmissive polarizing plate is usually disposed on the back side of the liquid crystal cell, and can form a liquid crystal display device or the like of a type in which reflection is from a visual confirmation side (display side) when a liquid crystal display device or the like is used in a relatively bright environment. An image is displayed by incident light, and an image is displayed using a built-in light source such as a backlight built in the back side of the semi-transmissive polarizing plate in a relatively dark environment. That is, the semi-transmissive polarizing plate can effectively form a liquid crystal display device or the like of the following type, that is, bright In the environment, the energy used by the light source such as the backlight can be saved, and the built-in light source can also be used in a relatively dark environment.

An elliptically polarizing plate or a circularly polarizing plate in which a phase difference plate is laminated on a polarizing plate will be described. A phase difference plate or the like is used when the linearly polarized light is changed to an elliptically polarized or circularly polarized light, or an elliptically polarized or circularly polarized light is changed to a linearly polarized light, or a polarized direction of a linearly polarized light is changed. In particular, as a phase difference plate which changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light, a so-called quarter-wavelength plate (also referred to as a λ/4 plate) can be used. A 1/2 wavelength plate (also known as a λ/2 plate) is commonly used to change the direction of polarization of linearly polarized light.

The elliptically polarizing plate can be effectively used to compensate (prevent) the coloring (blue or yellow) generated by the birefringence of the liquid crystal layer of a super twisted nematic (STN) liquid crystal display device, thereby performing the coloring without the above coloring. White and black display cases, etc. Further, it is preferable to control the three-dimensional refractive index to compensate (prevent) the coloring which occurs when the screen of the liquid crystal display device is observed obliquely. The circularly polarizing plate can be effectively used, for example, in the case of adjusting the color tone of an image of a reflective liquid crystal display device of a color display image, and also has a function of preventing reflection. Specific examples of the phase difference plate include a suitable polymerization of polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene or other polyolefins, polyarylates, polyamines, and the like. A birefringent film formed by stretching a film, an alignment film of a liquid crystal polymer, an alignment layer supporting a liquid crystal polymer with a film, and the like. The phase difference plate may have an appropriate phase difference corresponding to a use target for compensating for coloring or viewing angle due to, for example, birefringence of various wavelength plates or liquid crystal layers, or may have two or more kinds of phase difference plates laminated. The optical characteristics such as phase difference are controlled.

Further, the elliptically polarizing plate or the reflective elliptically polarizing plate is formed by laminating a polarizing plate, a reflective polarizing plate, and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like may be formed by a combination of a (reflective) polarizing plate and a phase difference plate, and is formed by sequentially laminating (reflective) polarizing plates and phase difference plates in the manufacturing process of the liquid crystal display device, as described above. As described above, an optical film such as an elliptically polarizing plate is formed in advance due to quality stability or lamination operation. Excellent in terms of properties, etc., and therefore has an advantage of improving the manufacturing efficiency of a liquid crystal display device or the like.

The viewing angle compensation film is a film for enlarging the viewing angle when the image of the liquid crystal display device is viewed from a direction that is not perpendicular to the screen. Such a viewing angle compensation retardation plate is formed, for example, by an alignment film such as a retardation film or a liquid crystal polymer, or an alignment layer such as a liquid crystal polymer supported on a transparent substrate. In general, a phase difference plate uses a polymer film having birefringence which is uniaxially stretched in the surface direction thereof, and a phase difference plate serving as a viewing angle compensation film, which has birefringence in which biaxial stretching is performed in the plane direction thereof. The polymer film is a biaxially stretched film such as a birefringent polymer or a tilted alignment film which is uniaxially stretched in the surface direction and which is also extended in the thickness direction thereof and whose refractive index is controlled in the thickness direction. The oblique alignment film may be, for example, a polymer film which is followed by a heat shrink film and which is subjected to elongation treatment due to heating, and which is subjected to elongation treatment or/shrinkage treatment of the polymer film, or polymerization of the liquid crystal. The object is inclined and the like. As the raw material polymer of the phase difference plate, the same polymer as that described in the above retardation plate can be used, and coloring such as a change in viewing angle which can be formed by the phase difference caused by the liquid crystal cell can be used. Or, a suitable polymer for the purpose of expanding the visual field of view.

Further, from the viewpoint of realizing a wide viewing angle of good visual observation, etc., it is preferable to use an optical alignment film formed of an alignment layer of a liquid crystal polymer, particularly an inclined alignment layer of a disc-type liquid crystal polymer, with a triethylene fluorene cellulose film. The optically retarded phase difference plate of the anisotropic layer.

A polarizing plate in which a polarizing plate and a brightness improving film are bonded together is usually disposed on the back side of the liquid crystal cell. The brightness-increasing film is a film which exhibits a characteristic of direct-polarized light of a specific polarization axis or circularly polarized light of a specific direction when natural light is incident by a backlight of a liquid crystal display device or the like, or reflection from the back side. Since the other light is transmitted, the polarizing plate is formed by laminating the brightness improving film and the polarizing plate, and light from a light source such as a backlight is incident to obtain a transmitted light of a specific polarized state, and light other than the specific polarized state is not transmitted. It is reflected. Brightening the light reflected on the film surface The reflective layer on the side is reversed and incident on the brightness enhancement film again, and a part or all of the light is transmitted as a specific polarization state to increase the light transmitted through the brightness enhancement film, and the polarized light that is supplied to the polarizer is hard to be absorbed. It can be used for the amount of light such as liquid crystal display image display, thereby increasing the brightness. In other words, when a light-increasing film is not used and a polarizer is transmitted from the back side of the liquid crystal cell to cause light to enter, the light having a polarization direction that does not coincide with the polarization axis of the polarizer is substantially polarized. Absorbed and thus unable to transmit through the polarizer. That is, although it differs depending on the characteristics of the polarizer used, about 50% of the light is absorbed by the polarizer, so that the amount of light used for liquid crystal image display or the like is correspondingly reduced, resulting in darkening of the image. The brightness enhancement film is reversely operated such that light having a polarization direction in which the polarizer can be absorbed is not incident on the polarizer but is temporarily reflected by the brightness enhancement film, and further reversed by a reflection layer or the like provided on the rear side thereof. Then, it is again incident on the brightness enhancement film, so that the brightness enhancement film only causes the polarization direction of the light reflected and inverted between the two to be transmitted through the polarized light in the polarization direction of the polarizer and supplied to the polarizer, so that it can be Light such as a backlight is effectively used in image display of a liquid crystal display device, thereby improving picture brightness.

A diffusion plate may be provided between the brightness enhancement film and the reflective layer or the like. The light in the polarized state reflected by the brightness enhancement film faces the reflection layer or the like, but the diffusing plate provided uniformly diffuses the passing light and eliminates the polarization state to be in a non-polarized state. That is, the diffusing plate restores the polarized light to the original natural light state. In the non-polarized state, that is, the light in the natural light state is emitted toward the reflective layer or the like, and is reflected by the reflective layer or the like, and then again incident on the brightness enhancement film through the diffusion plate. By providing a diffusing plate between the brightness improving film and the reflective layer or the like to restore the polarized light to the original natural light state, the brightness of the display screen can be maintained, and the brightness unevenness of the display screen can be reduced, thereby providing a uniform and bright picture. . By providing the diffusing plate, the number of repeated reflections of the primary incident light is appropriately increased, and the diffusion function of the diffusing plate is matched to provide a uniform and bright display screen.

As the brightness-enhancing film, for example, a multilayer laminated film having a dielectric film or a multilayer laminated body having a different refractive index anisotropy can be used, and a film which transmits a linear polarized light of a specific polarizing axis and reflects other light characteristics can be used. , such as an alignment film of a cholesteric liquid crystal polymer or a film which supports the alignment liquid crystal layer on a film substrate, and exhibits a film which reflects light of any of left-handed or right-handed circular light and transmits other light. Suitable film.

Therefore, in the brightness enhancement film of the type in which the linear polarization of the specific polarization axis is transmitted, the transmission light can be directly incident on the polarizing plate by the direct polarization axis, thereby suppressing the absorption loss due to the polarizing plate, and The light is transmitted efficiently. On the other hand, in a brightness enhancement film of a type in which a circularly polarized light is transmitted as in a cholesteric liquid crystal layer, circularly polarized light can be directly incident on the polarizer, but from the viewpoint of suppressing absorption loss, it is preferable to pass the phase. The difference plate linearly polarizes the circular polarized light and then enters the polarizing plate. Furthermore, circularly polarized light can be converted into linearly polarized light by using a quarter-wave plate as the phase difference plate.

A phase difference plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region can be obtained, for example, by using a light-colored light having a wavelength of 550 nm as a quarter-wave plate. The phase difference layer that functions is overlapped with a phase difference layer that exhibits other phase difference characteristics, for example, a phase difference layer that functions as a 1/2 wavelength plate. Therefore, the phase difference plate disposed between the polarizing plate and the brightness enhancement film can be formed of one or two or more layers of retardation layers.

Further, in the case of the cholesteric liquid crystal layer, a material having a different reflection wavelength may be combined to form an arrangement structure in which two or more layers are superimposed, thereby obtaining a circularly polarized light in a wide wavelength range such as a visible light region. Based on this, a transmissive circularly polarized light of a wider wavelength range can be obtained.

Further, the polarizing plate may be formed by laminating a polarizing plate and two or more optical layers, as in the above-described polarizing partial release polarizing plate. Therefore, a reflective elliptically polarizing plate or a semi-transmissive elliptically polarizing plate in which the above-described reflective polarizing plate or semi-transmissive polarizing plate and retardation plate are combined may be used.

The optical film in which the optical layer is laminated on a polarizing plate can be formed by sequentially laminating in a manufacturing process such as a liquid crystal display device. However, in order to form an optical film in advance, quality stability or assembly work is required. Excellent, and therefore has an advantage that the manufacturing steps of the liquid crystal display device and the like can be improved. An appropriate bonding mechanism such as an adhesive layer can be used in the laminate. When the polarizing plate or other optical film is continued, the optical axes can be appropriately arranged according to the target phase difference characteristics and the like.

An adhesive layer for adhering to another member such as a liquid crystal cell may be provided on the polarizing plate or the optical film on which at least one polarizing plate is laminated. The adhesive for forming the adhesive layer is not particularly limited, and for example, a polymer such as an acrylic polymer, an anthrone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine or a rubber may be appropriately used. Adhesive for base polymers. In particular, an adhesive excellent in optical transparency, such as an acrylic adhesive, which exhibits excellent wettability and cohesiveness and adhesive properties, and excellent in weather resistance and heat resistance can be preferably used.

In addition, in addition to the above, the foaming phenomenon or the peeling phenomenon which occurs due to moisture absorption, the optical characteristics are deteriorated due to the difference in thermal expansion, the liquid crystal cell is warped, and the liquid crystal display device having excellent durability is formed with high quality. From the viewpoint of the viewpoint, an adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

The adhesive layer may contain, for example, a natural or synthetic resin, particularly a filler, a pigment, a colorant, an antioxidant, etc. formed of a tackifying resin or a glass fiber, a glass bead, a metal powder, and other inorganic powder, and the like, and being added to the adhesive layer. Additives in the middle. Further, it may be an adhesive layer containing fine particles and exhibiting light diffusibility.

When an adhesive layer is attached to one surface or both surfaces of the polarizing plate or the optical film, it can be carried out in an appropriate manner. As an example, for example, about 10 to 40 weights obtained by dissolving or dispersing a base polymer or a composition thereof in a solvent formed of a separate substance or a mixture of a suitable solvent such as toluene or ethyl acetate can be used. a percentage of the adhesive solution, and then directly attached to the polarizing plate by a suitable expansion method such as casting or coating. The method on the optical film; or the manner of transferring and adhering the adhesive layer to the polarizing plate or the optical film after forming the adhesive layer on the spacer.

The adhesive layer may also be disposed on one surface or both surfaces of the polarizing plate or the optical film as an overlapping layer of layers of different compositions or types. Further, when provided on both surfaces, an adhesive layer of a different composition, type, thickness or the like may be formed on the front and back surfaces of the polarizing plate or the optical film. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use or the adhesion, etc., and is usually 1 to 40 μm, preferably 5 to 30 μm, particularly preferably 10 to 25 μm. When the thickness is less than 1 μm, the durability is deteriorated, and when the thickness is more than 40 μm, floating or peeling due to foaming or the like is likely to occur, and the appearance is deteriorated.

For the exposed surface of the adhesive layer, it may be temporarily adhered to the spacer to prevent contamination or the like before use. Thereby, the phenomenon of contact with the adhesive layer under normal operation conditions can be prevented. As the spacer, in order to satisfy the above-described thickness conditions, for example, a suitable release agent such as an anthrone or a long-chain alkyl group, a fluorine-based or a molybdenum sulfide may be used for the plastic film, the rubber sheet, the paper, the cloth, or the like. A suitable sheet such as a woven fabric, a mesh, a foamed sheet or a metal foil, or a laminate thereof is used as a suitable spacer conventionally used for coating.

In order to improve the adhesion between the polarizing plate and the adhesive layer, a fixing layer may be provided between the layers.

The material for forming the above-mentioned pinned layer is preferably a fixing agent selected from the group consisting of polyurethanes, polyesters, and polymers containing an amine group in the molecule, and particularly preferably a polymer having an amine group in the molecule. A polymer containing an amine group in the molecule can ensure good adhesion because the amine group in the molecule exhibits an interaction with a carboxyl group or the like in the adhesive or an ionic interaction.

Examples of the polymer having an amine group in the molecule include an amine group-containing monomer such as polyethyleneimine, polyarylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine or dimethylaminoethyl acrylate. Polymers, etc.

In the above fixed layer, an antistatic agent may be added in order to impart antistatic properties. use Examples of the antistatic agent that imparts antistatic properties include ionic surfactants; conductive polymers such as polyaniline, polythiophene, polypyrrole, and polyquinoxaline; and metal oxides such as tin oxide, cerium oxide, and indium oxide. It is particularly preferable to use a conductive polymer system from the viewpoints of stability of heat and humidification in terms of optical characteristics, appearance, antistatic effect, and antistatic effect. Among them, a water-soluble conductive polymer such as polyaniline or polythiophene or a water-dispersible conductive polymer is particularly preferably used. When a water-soluble conductive polymer or a water-dispersible conductive polymer is used as a material for forming an antistatic layer, deterioration of the chemical film substrate by the organic solvent can be suppressed at the time of coating.

Furthermore, in the present invention, for example, a salicylate-based compound, a benzophenol compound, or a benzoate may be used for each layer such as a polarizing plate, a transparent protective film, or an optical film on which the polarizing plate is formed. A triazole compound, a cyanoacrylate compound, a nickel salt compound compound, or the like, which has an ultraviolet absorbing ability by a method such as treatment with an ultraviolet absorber.

The polarizing plate or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the previous method. In other words, the liquid crystal display device can be formed by appropriately assembling a liquid crystal cell, a polarizing plate or an optical film, and a lighting system such as an illumination system added as needed, and incorporating the driving circuit or the like, in the present invention, except The polarizing plate or the optical film of the present invention is not particularly limited, and may be formed according to the conventional method. For the liquid crystal cell, any type of liquid crystal cell such as TN (Twisted Nematic) or STN type, π type, VA type, or IPS type can be used.

According to the present invention, a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a liquid crystal display device in which a backlight or a reflecting plate is used in an illumination system can be used. At this time, the polarizing plate or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. When the polarizing plate or the optical film is disposed on both sides, the materials may be the same material or different materials. Moreover, in forming a liquid crystal display device In the appropriate position, one or more layers of suitable components such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a tantalum array, a lens array sheet, a light diffusing plate, and a backlight may be disposed at appropriate positions.

Next, an organic electroluminescence device (organic EL display device) will be described. In general, in an organic EL display device, a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form an illuminant (organic electroluminescence). Here, the organic light-emitting layer is a laminate of various organic films, and is known to have a laminate of a hole injection layer formed of a triphenylamine derivative or the like and a light-emitting layer formed of a fluorescent organic solid such as ruthenium. Alternatively, the light-emitting layer may be laminated with an electron injecting layer formed of a perylene derivative or the like, or a combination of the hole injecting layer, the light-emitting layer, and the electron injecting layer.

The organic EL display device emits light by applying a voltage to the transparent electrode and the metal electrode, thereby injecting holes and electrons into the organic light-emitting layer, and recombining the holes and electrons. The energy excites the fluorescent material and emits light when the excited fluorescent material returns to the ground state. The recombination mechanism in the middle is the same as that of the ordinary diode, and it can be inferred that the current and the luminescence intensity show a strong nonlinearity accompanying the rectification with respect to the applied voltage.

In the organic EL display device, in order to extract light generated in the organic light-emitting layer, at least one of the electrodes must be transparent, and a transparent electrode made of a transparent conductor such as indium tin oxide (ITO) is usually used as an anode. On the other hand, in order to facilitate the injection of electrons and improve the luminous efficiency, it is important to use a metal electrode such as Mg-Ag or Al-Li for a substance having a small work function in the cathode.

In the organic EL display device having such a configuration, the organic light-emitting layer is formed of an extremely thin film having a thickness of about 10 nm. Therefore, the organic light-emitting layer is also the same as the transparent electrode, so that the light is substantially completely transmitted. As a result, light that is incident from the surface of the transparent substrate and transmitted through the transparent electrode and the organic light-emitting layer after being emitted without being emitted, and then reflected by the metal electrode is again emitted toward the surface side of the transparent substrate, and therefore, when visually observed from the outside, the organic EL Device display The face is like a mirror.

In the organic EL display device including the organic electroluminescence device, the organic electroluminescence device has a transparent electrode on the surface side of the organic light-emitting layer that emits light by applying a voltage, and has a metal electrode on the back side of the organic light-emitting layer. A polarizing plate is disposed on a surface side of the transparent electrode, and a phase difference plate is disposed between the transparent electrode and the polarizing plate.

Since the phase difference plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, the polarizing action has an effect that the mirror surface of the metal electrode cannot be visually observed from the outside. In particular, when the retardation plate is formed by a quarter-wavelength plate and the angle formed by the polarization directions of the polarizing plate and the phase difference plate is adjusted to π/4, the mirror surface of the metal electrode can be completely shielded.

In other words, the external light incident on the organic EL display device is transmitted only through the linearly polarized light component due to the polarizing plate. The linearly polarized light is usually converted into elliptically polarized light by a phase difference plate, and especially when the phase difference plate is a quarter wave plate and the angle between the polarizing plate and the polarization direction of the phase difference plate is π/4, Round polarized light.

The circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic film, and is reflected by the metal electrode, and then transmitted through the organic film, the transparent electrode, and the transparent substrate again, and is again converted into linearly polarized light by the phase difference plate. Since the linear polarized light is orthogonal to the polarizing direction of the polarizing plate, it cannot be transmitted through the polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

[Examples]

The embodiments of the present invention are described below, but the embodiments of the present invention are not limited thereto.

<Tg: glass transition temperature>

The measurement was carried out at a temperature elevation rate of 10 ° C /min using a glass transition temperature differential scanning calorimetry (DSC). In the sample, 5 mg of the sample was placed in an aluminum gland type container and crimped for use.

<gel fraction>

Using an applicator, the adhesive used in each example was applied to a release film, and another release film was adhered thereto, and then an electron beam was irradiated under the same conditions as in each case to harden the adhesive to form an adhesive. Floor. The release film was peeled off from both sides of the obtained adhesive layer, about 200 mg was taken out from the adhesive layer, and it weighed, and the weight (W1) was computed. Then, it was wrapped in a microporous tetrafluoroethylene film (film weight: W2) and tied with a rope, and immersed in about 50 ml of toluene for 4 days, and then the soluble component was extracted. After drying at 110 ° C for 1 hour in an incubator, the total weight (W3) was measured. From these measured values, the gel fraction (% by weight) of the adhesive layer was determined according to the following formula.

Gel fraction (% by weight) = ((W3-W2) / W1) × 100

(polarizer)

A polyvinyl alcohol film having an average polymerization degree of 2,400, a saponification degree of 99 mol%, and a thickness of 75 μm was immersed in warm water of 30 ° C for 60 seconds to swell. Then, it was dyed for 1 minute while being 0.3 minute by weight (weight ratio: iodine/potassium iodide = 0.5/8) in an iodine solution at 30 ° C, and extended to 3.5 times on one side. Thereafter, the total stretching ratio was extended to 6 times while immersing in a 4 wt% aqueous solution of borate ester at 65 ° C for 0.5 minute. After stretching, it was dried in an incubator at 70 ° C for 30 minutes to obtain a polarizer having a thickness of 26 μm. The water content of the polarizer was 13.5 weight percent.

(transparent protective film)

A lactone polymethyl methacrylate film (LMMA, lactonization ratio 20%, thickness 30 μm, Re=0 nm, Rth=0 nm) was used.

(phase difference)

For the measurement of the phase difference, a phase difference meter based on the principle of the parallel polarizer rotation method [manufactured by the Prince Measuring Machine Co., Ltd., product name "KOBRA21-ADH"] is used, and nx, ny is measured based on the wavelength value of 590 nm. The value of nz and the film thickness (d) were determined as the front phase difference Re and the thickness direction phase differences Rth and Nz. [Where, the slow axis direction of the film, the direction of the fast axis, and The refractive indices in the thickness direction are set to nx, ny, nz, respectively, and d (nm) is the thickness of the film. The direction of the slow axis is the direction in which the refractive index in the film plane is the largest. ].

Example 1

(adhesive: hardening component)

As the adhesive, N-propylene decylmorpholine was used.

(production of polarizing plate)

On one side of the above transparent protective film, the above-mentioned adhesive was applied to a thickness of 5 μm using a micro gravure coater (gravure roll: #180, rotation speed: 140%/linear velocity) to form a transparent protective film with an adhesive. . Then, the above-mentioned adhesive transparent protective film was bonded to both surfaces of the above polarizer using a roller machine. The self-adhesive adhesive is irradiated with electron beams on the transparent protective film side (both sides) to obtain a polarizing plate having a transparent protective film on both sides of the polarizer. The linear velocity is 20 m/min, the acceleration voltage is 250 kV, and the illumination line amount is 20 kGy. The Tg was 140 ° C and the gel fraction was 72% by weight.

Examples 2 to 21 and Comparative Examples 1 to 11

In the same manner as in the first embodiment, a polarizing plate was obtained in the same manner as in the first embodiment except that the type of the curable component, the ratio of the adhesive layer, and the thickness of the adhesive layer were changed as shown in Table 1. In addition, in Comparative Examples 4 to 6, 3 parts by weight of a polymerization initiator was added to 100 parts by weight of the curable component. Further, the gravure roll was changed to a mirror surface at 0.1 μm, 0.3 μm, and 0.5 μm depending on the thickness of the adhesive layer, and changed to #300 at 0.8 μm and 1 μm, changed to #280 at 2 μm, and changed to #250 at 3 μm at 4 μm. And 4.2μm change to #220, change to #180 at 5μm and 6μm, and change to #120 at 10μm. The Tg and gel fraction of each of the adhesive layers of each example are shown in Table 1.

[Evaluation]

The polarizing plates obtained in the examples and the comparative examples were subjected to the following evaluations. The results are shown in Table 1.

<Durability>

The obtained polarizing plate was cut into a size of 15 inches diagonally, and an acrylic adhesive was adhered to both surfaces of a 0.5 mm thick alkali-free glass in the direction of a crossed polarizer to prepare a sample. The sample was placed under the following conditions.

Condition (1): The thermal shock of -40 to 85 ° C is carried out for 30 minutes × 200 times.

Condition (2): 30 to 70 times of thermal shock of -30 to 70 ° C

The state of the time-dependent polarizing plate in each of the above conditions was evaluated by the following criteria.

◎: No cracks were generated.

○: Short cracks of 5 mm or less were produced only at the ends.

△: Short-line cracks were generated at locations other than the ends. However, the polarizing plate was not separated into two or more portions due to the line.

×: Cracks are generated at locations other than the ends. The polarization is separated into two or more parts by the line.

<peel strength>

The obtained polarizing plate was cut into a size of 15 mm × 15 mm to prepare a sample. The sample was bonded to a glass plate using a double-sided tape (Nitto Electric Co., Ltd., No. 500). On the sample (polarizing plate), a boundary was previously set between the transparent protective film and the polarizer, and the boundary was stuck on a variable angle peeling tester (manufactured by Asahiseiko Co., Ltd.) to measure the peel strength (N/15 mm). The measurement conditions were set to normal temperature (23 ° C), peeling angle: 90 degrees, and peeling speed: 3000 mm/min. The values obtained by averaging the data between 50 mm and 100 mm in the obtained measurement data are shown in Table 1.

In Table 1, ACMO: N-propylene decylmorpholine, DA-141: 2-hydroxy-3-phenoxypropyl acrylate (manufactured by Nagase ChemteX Co., Ltd., DA-141), HEAA: N-hydroxyl Ethyl acrylamide, N-MAN: N-methylol acrylamide, NIPAM: N-isopropyl acrylamide, EB: electron ray, UV: ultraviolet light.

Claims (11)

A polarizing plate characterized in that a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer, and an adhesive layer is formed of an active energy ray-curable adhesive containing at least one hardening component, and an adhesive layer The Tg is 60 ° C or more, and the thickness of the adhesive layer is 0.01 to 7 μm. The polarizing plate of claim 1, wherein when the Tg (° C.) of the adhesive layer is defined as A and the thickness (μm) of the adhesive layer is defined as B, the numerical formula (1): A-12 is satisfied. ×B>58. The polarizing plate of claim 1, wherein the adhesive layer has a gel fraction of 50% by weight or more. The polarizing plate of claim 1, wherein the hardenable component is a compound having a (meth) acrylonitrile group. The polarizing plate of claim 4, wherein the hardening component contains the formula (1): CH ₂ = C(R ¹ )-CONR ² (R ³ ) (R ¹ represents a hydrogen atom or a methyl group, and R ² represents hydrogen A straight or branched alkyl group having 1 to 4 carbon atoms which may have a hydroxyl group, a mercapto group, an amine group or a quaternary ammonium group, and R ³ represents a hydrogen atom or a linear chain having 1 to 4 carbon atoms or a branched alkyl group which does not contain R ² and R ³ as a hydrogen atom, or a combination of R ² and R ³ to form a 5-membered ring or a 6-membered ring which may also contain an oxygen atom. Is a monomer. The polarizing plate of claim 5, wherein the N-substituted amide amine system is selected from the group consisting of N-hydroxyethyl acrylamide, N-methylol acrylamide, N-isopropyl acrylamide, and N-propylene. At least one of decylmorpholine. The polarizing plate of claim 4, which further contains a monofunctional (meth) acrylate having an aromatic ring and a hydroxyl group as a curable component. The polarizing plate of claim 1, wherein the active energy ray-curable adhesive is an electron beam hardening type adhesive. The polarizing plate of claim 1, wherein the transparent protective film is at least one selected from the group consisting of a cellulose resin, a polycarbonate resin, a cyclic polyolefin resin, and a (meth)acrylic resin. An optical film characterized in that it is laminated with at least one polarizing plate of claim 1. An image display device characterized by using a polarizing plate as claimed in claim 1.