WO2005061648A1 - Pressure-sensitive adhesive composition for optical film, pressure-sensitive adhesive layer for optical film, pressure-sensitive adhesive type optical film, and image display - Google Patents

Abstract

A pressure-sensitive adhesive composition for optical films which can effectively inhibit light leakage and window-frame-pattern unevenness even under the high-temperature conditions of about 120°C. The pressure-sensitive adhesive composition for optical films comprises: a (meth)acrylate polymer having a weight-average molecular weight of 500,000 to 2,500,000; a (meth)acrylate oligomer having a weight-average molecular weight of 1,000 to 10,000 obtained by polymerization with a chain transfer agent having a reactive carbon-carbon double bond; and a crosslinking agent. It is characterized in that the content of the chain transfer agent in the composition is 0.3 or lower in terms of absorbance ratio [(absorbance assignable to C=C vibration in the chain transfer agent in 780±20 cm-1 region)/(absorbance assignable to C-H vibration in the polymer and oligomer in 740±20 cm-1 region)].

Description

 Specification

 Pressure-sensitive adhesive composition for optical film, pressure-sensitive adhesive layer for optical film, pressure-sensitive optical film and image display device

 Technical field

 The present invention relates to a pressure-sensitive adhesive composition for an optical film. The present invention also relates to a pressure-sensitive adhesive layer for an optical film formed from the pressure-sensitive adhesive composition for an optical film. Furthermore, the present invention relates to an adhesive optical film having the adhesive layer, and further to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP using the adhesive optical film. Examples of the optical film include a polarizing plate, a retardation plate, an optical compensation film, a brightness enhancement film, and a film in which these are laminated.

 Background art

 [0002] An optical film used for a liquid crystal display device or the like, for example, a polarizing plate or a retardation plate, is attached to a liquid crystal cell using an adhesive. The material used for such an optical film has a large expansion and contraction under heating or humidification conditions, so that it tends to float or peel off after the application. Therefore, adhesives for optical films are required to have durability that can be used under heating conditions and humidification conditions.

 [0003] In addition, pressure-sensitive adhesives for optical films are required to uniformly relieve stresses caused by dimensional changes of optical films such as polarizing plates under heating or humidifying conditions. . When the stress relaxation property is poor, residual stress remains in an optical film such as a polarizing plate, and adverse effects such as polarization loss (light leakage) occur.

 [0004] Various materials have been proposed as adhesives used for such optical films. For example, attempts have been made to blend a high molecular weight polymer with a low molecular weight polymer to improve the stress relaxation of the pressure-sensitive adhesive!

[0005] Patent Document 1 discloses a pressure-sensitive adhesive composition having a crosslinked structure obtained by mixing 20 to 200 parts by weight of a low molecular weight polymer having a weight average molecular weight of 30,000 or less with 100 parts by weight of a high molecular weight polymer having a high functional group ratio. Has been proposed. According to the pressure-sensitive adhesive composition, the three-dimensional structure of the high molecular weight component prevents foaming and peeling under high temperature and high humidity, and prevents internal It is disclosed that stress can be absorbed by low molecular weight polymer components.

 [0006] Patent Document 2 proposes a pressure-sensitive adhesive composition in which a low molecular weight polymer having a weight average molecular weight of 500,000 or less is blended with a high molecular weight polymer. According to the disclosed pressure-sensitive adhesive composition, it is disclosed that stress concentration is relieved, white spots in the liquid crystal cell are suppressed, and no adhesive residue or fogging occurs in the liquid crystal cell after peeling.

 [0007] In Patent Document 3, 1 to 50 parts by weight of a low molecular weight polymer having a weight average molecular weight of 5,000 to less than 500,000 is blended with 100 parts by weight of a high molecular weight polymer, and one of the high molecular weight polymer and the low molecular weight polymer is mixed. A pressure-sensitive adhesive composition containing a nitrogen-containing functional group has been proposed. According to the powerful pressure-sensitive adhesive composition, it is disclosed that the strength of the bond between the nitrogen-containing functional group and the adherend is excellent, the durability is excellent, and the white drop can be suppressed by following the expansion and contraction of the polarizing plate. ing.

 [0008] Patent Document 4 proposes a pressure-sensitive adhesive composition comprising 100 parts by weight of a high-molecular-weight polymer, 5 to 100 parts by weight of an acrylic oligomer having a weight average molecular weight of 1,000 to 10,000, and a bifunctional crosslinking agent. I have. It is disclosed that such a pressure-sensitive adhesive composition has excellent adhesion to an adherend and has good stress relaxation properties so that durability and white spots can be suppressed.

 [0009] Patent Document 5 discloses that 100 to 100 parts by weight of a high molecular weight polymer is mixed with 10 to 100 parts by weight of a low molecular weight polymer having a glass transition point of 0 to 80 ° C and a low molecular weight of 3 to 100,000, Has been proposed. It is disclosed that such an adhesive composition can cope with peeling, foaming, and white drop phenomenon.

 [0010] By using the above-mentioned pressure-sensitive adhesive composition, it is possible to alleviate the stress caused by the dimensional change of the optical film to some extent, and to prevent the loss of polarization (light leakage) at a high temperature. Can be.

However, in recent years, liquid crystal display devices are often used under severer high-temperature conditions, such as for use in vehicles, and further higher durability is desired. Under such high-temperature conditions, the optical film affixed to a substrate such as glass undergoes oxidative degradation at the outside where it is exposed to the atmosphere. The so-called “window frame-like unevenness phenomenon” occurs because the polarization loss (light leakage) differs between inside and outside There is a tendency.

 [0012] In order to solve the above problem, a technique has been disclosed in which an antioxidant and a cross-linking agent are added to an adhesive to suppress the light leakage and the frame phenomenon (Patent Document 6). In addition, a technique has been disclosed in which a crosslinking agent and a radical scavenger are added to an adhesive composition to suppress degradation of the adhesive due to hydrolysis (Patent Document 7).

However, under high-temperature conditions of 120 ° C. or higher, even if the above-mentioned additives are blended, it is not possible to effectively suppress the polarization omission (light leakage) and the window frame-like unevenness! /.

 Patent Document 1: Japanese Patent Application Laid-Open No. 10-279907

 Patent Document 2: Japanese Patent Application Laid-Open No. 2000-109771

 Patent Document 3: JP 2000-89731 A

 Patent Document 4: JP 2001-335767 A

 Patent Document 5: JP-A-2002-121521

 Patent Document 6: JP-A-2003-49143

 Patent Document 7: JP-A-2002-30264

 Disclosure of the invention

 Problems to be solved by the invention

An object of the present invention is to provide a pressure-sensitive adhesive composition for an optical film that can effectively suppress light leakage and window frame-like unevenness even under a high temperature condition of about 120 ° C. Another object of the present invention is to provide a pressure-sensitive adhesive layer for an optical film formed from the pressure-sensitive adhesive composition for an optical film. Still another object of the present invention is to provide an adhesive optical film and an image display device having the adhesive layer. Means for solving the problem

 [0015] The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the above object can be achieved by the following adhesive composition for an optical film, and have completed the present invention.

That is, the present invention provides a (meth) acrylate polymer having a weight-average molecular weight of 500,000 to 2.5 million, a weight-average molecular weight of 1000-1 polymerized using a chain transfer agent having a reactive carbon-carbon double bond. A pressure-sensitive adhesive composition containing 10,000 (meth) acrylate copolymers and a cross-linking agent, and a chain transfer agent content in the composition, an absorbance ratio [(780 ± 20c The absorbance based on the C = C vibration of the chain transfer agent in the range of π ¹ ) Z (absorbance based on the CH vibration of the polymer and oligomer in the range of 740 × 20 cm- ¹ ) is 0.3 or less. And a pressure-sensitive adhesive composition for an optical film.

The present inventors have found that the cause of the window frame-like unevenness phenomenon caused by the deterioration of the outside of the optical film under a high temperature or high temperature and high humidity is a reactive carbon-carbon double bond contained in the pressure-sensitive adhesive composition. Rate of the chain transfer agent having a reactive carbon-carbon double bond in the composition, the absorbance ratio [(C = C vibration of the chain transfer agent in the range of (780 ± 20 cm- ¹ ) Absorbance based on Z) (absorbance based on CH vibration of the polymer and oligomer in the range of 740 ± 20 cm- ¹ )] of 0.3 or less ensures that light leakage and window frame-like unevenness can be effectively suppressed. I found it.

[0018] The content of the reactive carbon double bond in the pressure-sensitive adhesive composition largely contributes to additives such as a polymerization initiator and a chain transfer agent. Among them, a window frame is formed due to degradation of a chain transfer agent having a reactive carbon-carbon double bond, such as _α -methylstyrene dimer, which is used in a large amount to control the molecular weight of the oligomer during oligomer production. It is considered that the mull phenomenon occurs. As the chain transfer agent, there is a chain transfer agent having no reactive carbon-carbon double bond, such as dodecyl mercaptan, mercaptoethyl alcohol, mercaptosuccinic acid, and thioglycolic acid. It is difficult to use viewpoints such as gender (for example, smell). Therefore, even when a chain transfer agent having a reactive carbon-carbon double bond is used during the production of an oligomer, it is important how to suppress light leakage and window frame-like unevenness.

[0019] In the present invention, from the viewpoint of handling properties and the like, the chain transfer agent is at least one selected from the group consisting of a-methylstyrene, α-methylstyrene dimer, and α-methylstyrene trimer. Is preferable. In particular, it is preferable that the chain transfer agent is an _α -methylstyrene dimer.

The pressure-sensitive adhesive layer for an optical film of the present invention is formed by crosslinking the pressure-sensitive adhesive composition for an optical film. The gel fraction of the crosslinked pressure-sensitive adhesive layer for an optical film is preferably 30 to 80% by weight. The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition can be set to have the predetermined gel fraction by using a cross-linking agent. Even after a long period of time, such as going through various processes after sticking to the liquid crystal cell, or being stored in a high-temperature, high-humidity state, it does not peel, float, or foam in the bonded state, improving durability. It comes out.

 The pressure-sensitive adhesive optical film of the present invention is obtained by forming the pressure-sensitive adhesive layer for an optical film on one or both surfaces of the optical film.

The present invention also relates to an image display device using at least one of the pressure-sensitive adhesive optical films.

 BEST MODE FOR CARRYING OUT THE INVENTION

The pressure-sensitive adhesive composition for an optical film of the present invention is obtained by polymerizing a (meth) acrylate polymer having a weight average molecular weight of 500,000 to 2.5 million and a chain transfer agent having a reactive carbon-carbon double bond. It is a pressure-sensitive adhesive composition containing a (meth) acrylate copolymer having an average molecular weight of 1,000 to 10,000 and a crosslinking agent, and the content of the chain transfer agent in the composition is determined by the absorbance ratio [(780 cm 20 cm— ^The absorbance based on the C = C vibration of the chain transfer agent in the range of ¹ ) Z (absorbance based on the CH vibration of the polymer and the oligomer in the range of 740 ± 20 cm- ¹ )] is 0.3 or less. And The (meth) acrylic polymer refers to an acrylic polymer and a Z or methacrylic polymer, and has the same meaning as (meth) in the present invention.

 The (meth) acrylic polymer is obtained by copolymerizing at least the (meth) acrylic ester and a monomer having a crosslinkable functional group, with the (meth) acrylic ester as a main component as a monomer component. Can be The copolymer form is not particularly limited, and may be any of random, block, or graft.

[0025] The (meth) acrylic acid ester constituting the main skeleton of the (meth) acrylic polymer is not particularly limited, but may be methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, or n-butyl. (Meth) acrylate, iso-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, lauryl (meth) acrylate , Stearyl (meth) atalylate, cyclohexyl (meth) atalylate, benzyl (meth) atalylate, methoxyethyl (meth) atalylate, ethoxymethyl (meth) atalylate, and phenoxicetyl (meth) atalylate No. They are They can be used alone or in combination.

 [0026] Examples of the monomer having a crosslinkable functional group include, for example, carboxyls such as (meth) acrylic acid, β-carpoxyshethyl (meth) atalylate, itaconic acid, crotonic acid, maleic acid, fumaric acid, and maleic anhydride. Group-containing monomer, 2-hydroxyethyl (meth) atalylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol mono (meth) acrylate, and aryl Hydroxyl group-containing monomers such as alcohols, epoxy group-containing monomers such as glycidyl (meth) acrylate, and amino group-containing monomers such as aminomethyl (meth) acrylate and dimethylaminoethyl (meth) acrylate ) Acrylamide, methylol (meth) acrylamide And methemoglobin Kishechiru (meth) amide group-containing monomers such as acrylamide, Bulle trimethoxysilane,

And acetoacetyl-group-containing monomers such as acetoacetoxityl (meth) acrylate. These can be used alone or in combination.

[0027] The monomer having a crosslinkable functional group is added in an amount of 0 based on 100 parts by weight of the (meth) acrylate.

It is preferable to use from 01 to 25 parts by weight, more preferably from 0.05 to 15 parts by weight.

Further, as other monomers, aromatic vinyl monomers such as styrene, α-methylstyrene and vinyl toluene, vinyl acetate, vinyl chloride, (meth) acrylonitrile and the like may be used alone or in combination.

[0029] The other monomer is preferably used in an amount of 100 parts by weight or less, more preferably 50 parts by weight or less, based on 100 parts by weight of the (meth) acrylate.

[0030] The weight average molecular weight of the (meth) acrylic polymer is from 500,000 to 250,000, preferably from 1,000,000 to 2,000,000. When the weight average molecular weight is less than 500,000, the adhesion to the adherend and the durability tend to be insufficient, and when the weight average molecular weight exceeds 2.5 million, the stress relaxation property against the expansion and contraction of the optical film decreases. There is a tendency.

[0031] The (meth) acrylic polymer can be produced by various known methods.

, A radical polymerization method such as a barta polymerization method, a solution polymerization method, and a suspension polymerization method can be appropriately selected.

[0032] Examples of the polymerization initiator include peroxides such as hydrogen peroxide, benzoyl peroxide, and t-butyl peroxide. It is desirable to use it alone, but in combination with a reducing agent Can also be used as a redox polymerization initiator. Examples of the reducing agent include ionic sulfites, bisulfites, salts of ions such as iron, copper, and cobalt salts, amines such as triethanolamine, and reducing sugars such as aldose and ketose. . Further, azoi conjugates are also preferred polymerization initiators, such as 2,2'-azobis 2-methylpropioamidine, 2,2'-azobis-2,4-dimethylvaleronitrile, and 2,2'-azobis Use N, N'-dimethylene isobutylamidate, 2,2, -azobisisobutymouth-tolyl, 2,2, -azobis-2-methyl-N- (2-hydroxyethyl) propionamide, etc. be able to. It is also possible to use two or more of the above polymerization initiators in combination.

[0033] The reaction temperature is usually about 50 to 85 ° C, and the reaction time is about 118 hours. Among the above-mentioned production methods, a solvent for the (meth) acrylic polymer, which is preferably a solution polymerization method, is generally a polar solvent such as ethyl acetate and toluene. The solution concentration is usually about 20-80% by weight.

 [0034] The (meth) acrylic oligomer can be produced by the same method as described above, using the (meth) acrylic acid ester as a monomer component.

 [0035] The weight average molecular weight of the (meth) acrylic oligomer is from 1,000 to 10,000, preferably from 2,000 to 10,000. If the weight average molecular weight is less than 1000, durability may be reduced, or the oligomer may bleed out and contaminate the adherend when the adhesive optical film is peeled off. On the other hand, if the weight average molecular weight exceeds 10,000, it is not preferable because the stress relaxation property against the expansion and contraction of the optical film decreases and the adhesive strength to the adherend increases.

 [0036] The weight average molecular weight of the (meth) acrylic oligomer can be adjusted by using a large amount of a polymerization initiator or using a chain transfer agent. As the polymerization initiator, the same one as described above can be used. In the present invention, a chain transfer agent having a reactive carbon-carbon double bond is used for adjusting the weight average molecular weight of the (meth) acrylic oligomer.

Examples of the chain transfer agent having a reactive carbon-carbon double bond include styrenes such as α-methylstyrene, α-methylstyrene dimer, and α-methylstyrene trimer; and 2,4-diphenyl-4-methyl- (1) Alkenes such as pentene; rosin esters having a conjugated double bond with a hydroxyl group; These may be used alone or in combination of two or more. Can be used together.

 [0038] In order to control the content of the chain transfer agent in the pressure-sensitive adhesive composition to 0.3 or less by the absorbance ratio, the chain transfer agent is used for 100 parts by weight of the raw material monomer of the (meth) acrylic oligomer. It is preferable to use the agent in an amount of 10 parts by weight or less, more preferably 5 parts by weight or less, and particularly preferably 1 part by weight or less.

 [0039] The amount of the (meth) acrylic oligomer to be added is not particularly limited, but is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, per 100 parts by weight of the (meth) acrylic polymer. Parts by weight, particularly preferably 10 to 20 parts by weight. If the amount of the (meth) acrylic oligomer exceeds 100 parts by weight, the durability is adversely affected, and it is difficult to control the absorbance ratio to 0.3 or less. On the other hand, if the amount is less than 5 parts by weight, the adhesion to the adherend (liquid crystal cell) increases, which is not preferable.

 [0040] The crosslinking agent is a polyfunctional compound capable of forming a crosslinked structure by reacting with a functional group of a (meth) acrylic polymer. For example, when a hydroxyl group is introduced as a functional group of the polymer, a crosslinking agent that forms a crosslinked structure with the hydroxyl group is used.

 Examples of the isocyanate-based cross-linking agent include tolylene diisocyanate, chlorobenzene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, and xylylene diisoate. Cyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and polyisocyanate obtained by adding these diisocyanate conjugates to trimethylolpropane or the like I-Shadow, Isocyanurate

And urethane prepolymer-type isocyanates obtained by subjecting these diisocyanate conjugates to an addition reaction with polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, and the like.

Examples of the epoxy-based cross-linking agent include ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,3-bis (N, N-diglycidylaminomethyl) cyclo Hexane, N, N, Ν ', Ν, 1-tetraglycidyl m-xylylenediamine, N, N, Ν', Ν-tetraglycidylaminophenol methane, triglycidyl isocyanurate, m— Ν , N—Diglycidide Laminophenol-glycidyl ether, N, N-diglycidyl toluidine, N, N-diglycidyl dilin and the like.

 [0043] Examples of the aziridine-based crosslinking agent include diphenylmethane 4,4'bis (1 aziridinecarboxamide), trimethylolpropanetri-18-aziridyl-propionate, tetramethylolmethanetri-aziridyl-propionate, and toluene 2,4. Bis (1-aziridincarboxamide), triethylenemelamine, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine, and trimethylolpropanetri-j8- (2-methylaziridine ) Propionate and the like.

 [0044] Examples of other crosslinking agents include melamine conjugates, metal salts, and metal chelate conjugates. Among these, an isocyanate-based crosslinking agent is preferably used. In particular, when a hydroxyl group is introduced into a (meth) acrylic polymer or the like when a hydroxyl group-containing monomer such as 2-hydroxyethyl acrylate is copolymerized during the production of the (meth) acrylic polymer or the like, a crosslinking agent is used. It is preferable to form a crosslinked structure of a (meth) acrylic polymer or the like by using an isocyanate compound.

 [0045] The blending of the crosslinking agent is not particularly limited, but it is preferable to blend the crosslinking agent so that the gel fraction of the crosslinked pressure-sensitive adhesive layer is 30 to 80% by weight. Further, it is preferable to adjust the amount of the crosslinking agent to be 40 to 60% by weight. When the gel fraction is less than 30% by weight, the adhesive layer does not have sufficient durability, the cohesive strength is low, and foaming tends to occur under high temperature conditions. On the other hand, when the gel fraction exceeds 80% by weight, the stress relaxation property is poor, and peeling, light leakage, and window frame-like unevenness tend to occur easily under high temperature, high temperature and high humidity conditions. In order to adjust the gel fraction in this manner, the force varies depending on the material used. Generally, the compounding amount of the crosslinking agent is 0.001 to 5 parts by weight, and more preferably 0. 01-2 parts by weight are preferred.

It is preferable that the pressure-sensitive adhesive composition for an optical film of the present invention contains a silane coupling agent. As the silane coupling agent, a conventionally known one can be used without any particular limitation. For example, epoxy group-containing silane couplings such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyljetoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane Agent: 3-aminopropyltrimethoxysilane, N Amino group-containing silane coupling agents such as -2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl N- (1,3-dimethylbutylidene) propylamine; 3-attaryloxypropyltriamine (Meth) acrylic group-containing silane coupling agents such as methoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.

The amount of the silane coupling agent is not particularly limited, but is preferably 0.01 to 1 part by weight, more preferably 0.02 to 100 parts by weight of the (meth) acrylic polymer. 0.6 parts by weight. If the amount of the silane coupling agent exceeds 1 part by weight, the adhesive strength to the adherend (liquid crystal cell) tends to increase, and if the amount is less than 0.01 part by weight, the durability of the pressure-sensitive adhesive layer tends to decrease. It is in.

 [0048] The pressure-sensitive adhesive composition for an optical film of the present invention may optionally contain an ultraviolet absorber, an aging inhibitor, a softener, a dye, a pigment, a filler, and the like.

 [0049] The pressure-sensitive adhesive composition for an optical film of the present invention prepared as described above has a content of the chain transfer agent in the composition of 0.3 or less, preferably 0.15 or less, according to the absorbance ratio. It is as follows. If the absorbance ratio exceeds 0.3, light leakage and window frame-shaped unevenness are likely to occur under high temperature or high temperature and high humidity conditions of about 120 ° C.

 [0050] The pressure-sensitive adhesive optical film of the present invention is obtained by forming a pressure-sensitive adhesive layer on one or both surfaces of the optical film with the pressure-sensitive adhesive composition for optical films.

 [0051] The method for forming the pressure-sensitive adhesive layer on the optical film is not particularly limited, and the pressure-sensitive adhesive composition is applied to a support (release sheet) that has been subjected to a release treatment, dried, and crosslinked to form a pressure-sensitive adhesive layer. A method of transferring this to an optical film, a method of directly applying a pressure-sensitive adhesive composition to the optical film, drying and crosslinking to form a pressure-sensitive adhesive layer can be used. As an application method, an arbitrary application method such as a Rhono coater such as a line coater or a gravure coater, a curtain coater, a lip coater, or a die coater can be employed. Usually, the thickness of the pressure-sensitive adhesive layer after drying is preferably from 2 to 500 μm, more preferably from 5 to 100 μm.

[0052] The surface of the pressure-sensitive adhesive layer may be protected with a protective sheet until it is practically used. The protective sheet may be made of paper, synthetic resin film such as polyethylene, polypropylene, polyethylene terephthalate, rubber sheet, paper, cloth, nonwoven fabric, net, foam sheet, or the like. Suitable thin leaf bodies such as metal foils and laminates thereof are exemplified. The surface of the protective sheet is subjected to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment as necessary to enhance the releasability of the adhesive layer strength! .

As the optical film, a film used for forming a liquid crystal display device or the like is used, and the type is not particularly limited. For example, an optical film includes a polarizing plate. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used.

 The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene / butyl acetate copolymer-based partially modified film, and iodine and a dichroic dye. And uniaxially stretched by adsorbing the dichroic substance of the above, polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Among these, a polybutyl alcohol-based film and a polarizer having a dichroic substance such as iodine are preferable. The thickness of these polarizers is not particularly limited. Generally, the thickness is about 5 to 80 m.

[0055] A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching is produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching the film to 3 to 7 times its original length. Can be. If necessary, it can be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride, or the like. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, dirt on the surface of the polyvinyl alcohol-based film and the antiblocking agent can be washed away, and swelling of the polyvinyl alcohol-based film reduces unevenness such as uneven dyeing. It also has the effect of preventing it. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be stretched and dyed with iodine. Stretching can be performed in an aqueous solution of boric acid or potassium iodide or in a water bath.

[0056] As a material for forming the transparent protective film provided on one or both surfaces of the polarizer, a material excellent in transparency, mechanical strength, heat stability, moisture shielding property, isotropy, and the like is preferable. Good. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cenorellose polymers such as diacetinoresenorelose and triacetinoresenorelose, acrylic polymers such as polymethyl methacrylate, polystyrene and Atari mouth-tri- Styrene-based polymers such as styrene copolymer (AS resin) and polycarbonate-based polymers. Further, polyethylene, polypropylene, polyolefin having a cyclo- or norbornene structure, polyolefin-based polymer such as ethylene-propylene copolymer, salt-dominated polymer, amide-based polymer such as nylon or aromatic polyamide, imide-based polymer, Sunolefon polymer, polyethenoresnolefon polymer, polyethenolethenoleketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene Polymers, epoxy polymers, blends of the above polymers, and the like are also examples of the polymer forming the transparent protective film. The transparent protective film can also be formed as a cured layer of a thermosetting or ultraviolet curable resin such as an acrylic, urethane, acrylic urethane, epoxy, or silicone resin.

 [0057] Also, a polymer film described in JP-A-2001-343529 (WO01Z37007), for example, (A) a thermoplastic resin having a substituted or Z or non-amide group in a side chain; A resin composition containing a thermoplastic resin having a substituted and Z-unsubstituted file and a -tolyl group in the chain is exemplified. A specific example is a resin composition film containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. As the film, a film such as a mixed extruded resin composition can be used.

 [0058] The thickness of the protective film can be determined as appropriate, but is generally about 11500 / zm in terms of workability such as strength and handleability, and thinness. In particular, one 300 / z m is preferred, and 5-200 / z m is more preferred.

 [0059] Further, it is preferable that the protective film is as colored as possible. Therefore, Rth =

[(nx + ny) / 2-nz]. d (where nx and ny are the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness) A protective film having a retardation value in the thickness direction of 90 nm- + 75 nm is preferably used. Such thickness direction By using a retardation value (Rth) of 90 nm- + 75 nm, the coloring (optical coloring) of the polarizing plate due to the protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably -80 nm- "h60 nm, particularly -70 nm-" h45 nm.

 As the protective film, a cellulosic polymer such as triacetyl cellulose is preferred from the viewpoints of polarization characteristics and durability. Particularly, a triacetyl cellulose film is preferable. When a protective film is provided on both sides of the polarizer, a protective film having the same polymer material strength may be used on the front and back sides, or a protective film having a different polymer material strength may be used. The polarizer and the protective film are usually in close contact with each other via an aqueous pressure-sensitive adhesive or the like. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex-based, a water-based polyurethane, and a water-based polyester.

 [0061] The surface of the transparent protective film on which the polarizer is not bonded may be subjected to a hard coat layer, an antireflection treatment, a treatment for preventing sticking, or a treatment for diffusion or antiglare.

 [0062] The hard coat treatment is performed for the purpose of preventing the surface of the polarizing plate from being scratched, and is, for example, a cure that is excellent in hardness, slip characteristics, and the like by an appropriate ultraviolet-curable resin such as an acrylic or silicone resin. The film can be formed by a method of adding a film to the surface of the transparent protective film. The anti-reflection treatment is performed for the purpose of preventing reflection of external light on the polarizing plate surface, and can be achieved by forming an anti-reflection film or the like according to the related art. The anti-sticking treatment is performed for the purpose of preventing adhesion to the adjacent layer.

The anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and hindering the visibility of light transmitted through the polarizing plate. For example, a sand blasting method and a boss processing method are used. The transparent protective film can be formed by imparting a fine uneven structure to the surface of the transparent protective film by an appropriate method such as a surface roughening method or a method of blending transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine unevenness include silica, alumina, titania, zircon, tin oxide, indium oxide, cadmium oxide, and acid having an average particle size of 0.5 to 50 μm. Inorganic fine particles that may also be conductive such as antimony, crosslinked or Transparent fine particles such as organic fine particles having the same strength as an uncrosslinked polymer are used. When forming the fine surface uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, and 5 to 25 parts by weight based on 100 parts by weight of the transparent resin forming the fine surface uneven structure. Is preferred. The anti-glare layer may also serve as a diffusion layer (such as a viewing angle expanding function) for diffusing light transmitted through the polarizing plate to increase the viewing angle and the like.

 The anti-reflection layer, anti-staking layer, diffusion layer, anti-glare layer and the like can be provided on the transparent protective film itself, and can be provided separately as an optical layer separately from the transparent protective film. It can also be provided.

 As the optical film of the present invention, for example, a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including a wavelength plate such as 1Z2 or 1Z4), a viewing angle compensation film, and a brightness enhancement film is formed. And an optical layer that may be used for the above. These can be used alone as the optical film of the present invention, or can be used as a single layer or two or more layers laminated on the above-mentioned polarizing plate in practical use.

 In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a transflective reflecting plate is further laminated on a polarizing plate, or an elliptically polarizing plate or a circle in which a retardation plate is further laminated on a polarizing plate. A polarizing plate, a wide viewing angle polarizing plate in which a viewing angle compensation film is further laminated on a polarizing plate, or a polarizing plate in which a brightness enhancement film is further laminated on a polarizing plate, are preferable.

 [0067] The reflective polarizing plate is provided with a reflective layer on the polarizing plate, and is used to form a liquid crystal display device or the like that reflects and reflects incident light from the viewing side (display side). In addition, there is an advantage that a built-in light source such as a backlight can be omitted, and the liquid crystal display device can be easily made thin. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer having a strength such as a metal is provided on one surface of the polarizing plate via a transparent protective layer or the like as necessary.

[0068] A specific example of the reflective polarizing plate is a transparent protective film that has been matt-treated as necessary and has a reflective layer formed by attaching a foil made of a reflective metal such as aluminum or the like to a vapor-deposited film. And so on. Further, there may be mentioned, for example, a transparent protective film in which fine particles are contained to form a fine surface unevenness structure and a reflective layer having a fine unevenness structure formed thereon. The reflective layer having the fine uneven structure described above diffuses incident light by irregular reflection, thereby increasing directivity. This has the advantage that the appearance can be prevented and the unevenness of light and dark can be suppressed. Further, the transparent protective film containing fine particles has an advantage that the incident light and its reflected light are diffused when passing through the transparent light-shielding film, so that uneven brightness can be further suppressed. The reflective layer having a fine irregular structure reflecting the fine irregular structure on the surface of the transparent protective film is formed by, for example, depositing a metal by an appropriate method such as a vapor deposition method such as a vacuum deposition method, an ion plating method, or a sputtering method or a plating method. It can be carried out by a method of directly attaching to the surface of the transparent protective layer.

 [0069] Instead of the method in which the reflective plate is directly applied to the transparent protective film of the polarizing plate, the reflective plate can also be used as a reflective sheet in which a reflective layer is provided on an appropriate film according to the transparent film. Since the reflective layer is usually made of a metallic material, its use in a state where the reflective surface is covered with a transparent protective film, a polarizing plate, or the like is intended to prevent a decrease in the reflectance due to oxidation and, as a result, a long-term increase in the initial reflectance. It is more preferable in terms of sustainability and avoidance of separate protective layer.

 [0070] The transflective polarizing plate can be obtained by forming a transflective reflective layer such as a half mirror that reflects and transmits light on the reflective layer. Transflective polarizing plate

Usually, it is provided on the back side of the liquid crystal cell, and when the liquid crystal display device or the like is used in a relatively bright atmosphere, the image is displayed by reflecting the incident light from the viewing side (display side), and relatively Depending on the atmosphere, a liquid crystal display device or the like that is built in the back side of a transflective polarizing plate and displays an image using a built-in light source such as a backlight can be formed.

. That is, a transflective polarizing plate can save energy for using a light source such as a knock light in a bright atmosphere, and can be used with a built-in light source even in a relatively small atmosphere. It is useful for forming.

 An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. When changing linearly polarized light to elliptically or circularly polarized light, elliptically or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light, a phase difference plate or the like is used. In particular, a so-called 1Z4 wavelength plate (also referred to as a λΖ plate) is used as a phase difference plate for changing linearly polarized light to circularly polarized light or for converting circularly polarized light to linearly polarized light. A 1Z2 wavelength plate (also referred to as λΖ2 plate) is usually used to change the polarization direction of linearly polarized light.

[0072] The elliptically polarizing plate is a birefringent liquid crystal layer of a super twisted nematic (STN) type liquid crystal display device. Coloring (blue or yellow) caused by folding is compensated (prevented), and is effectively used in the case of the above-mentioned coloring and black-and-white display. Further, a device in which a three-dimensional refractive index is controlled is preferable because coloring (coloring) generated when the screen of the liquid crystal display device is viewed from an oblique direction can be compensated (prevented). The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflection type liquid crystal display device that displays an image in color, and also has an antireflection function.

 Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an alignment film of a liquid crystal polymer, and an alignment layer of a liquid crystal polymer supported by a film. Can be Although the thickness of the retardation plate is not particularly limited, it is generally about 20 to 150 / zm.

 [0074] Examples of the polymer material include polybutyl alcohol, polybutyral, polymethylvinylinoleether, polyhydroxyethynoleatalylate, hydroxyethynolecellulose, hydroxypropylcellulose, methinoresenolylose, polycarbonate, and polybutylene. Arylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyethenoresulfone, polyphenylene sulfide, polyphenylene oxide, polyallyl sulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose-based polymer, Examples include norbornene-based resins, and various binary and ternary copolymers thereof, graph copolymers, and blends thereof. These polymer materials become oriented materials (stretched films) by stretching or the like.

 As the liquid crystal polymer, for example, a conjugated linear atomic group imparting liquid crystal orientation is used.

There are various main chain and side chain types in which (mesogen) is introduced into the main chain and side chain of the polymer. Specific examples of the main chain type liquid crystal polymer include a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility, for example, a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer. can give. Specific examples of the side-chain type liquid crystalline polymer include polysiloxane, polyatalylate, polymethacrylate or polymalonate having a main chain skeleton, and a nematic alignment imparted through a spacer portion comprising a conjugated atomic group as a side chain. And the like having a mesogenic moiety which is a unitary force of the para-substituted cyclic compound. These liquid crystalline polymers are, for example, those obtained by rubbing the surface of a thin film of polyimide or polyvinyl alcohol formed on a glass plate, This is carried out by spreading a solution of a liquid crystalline polymer on an alignment treatment surface such as one obliquely deposited with silicon and subjecting it to heat treatment.

 The retardation plate may be one having an appropriate retardation in accordance with the intended use, such as, for example, various wavelength plates or ones for the purpose of compensating coloring or viewing angle due to birefringence of the liquid crystal layer. A device in which optical characteristics such as phase difference are controlled by laminating more than two kinds of phase difference plates may be used.

 [0077] The elliptically polarizing plate and the reflection type elliptically polarizing plate are obtained by laminating a polarizing plate or a reflection type polarizing plate and a retardation plate in an appropriate combination. A strong elliptically polarizing plate or the like can also be formed by sequentially and separately laminating a (reflection type) polarizing plate and a retardation plate in the manufacturing process of a liquid crystal display device so as to form a combination. An optical film such as an elliptically polarizing plate as described above is advantageous in that it has excellent quality stability and laminating workability, and can improve the production efficiency of a liquid crystal display device and the like.

 [0078] The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed in a direction not perpendicular to the screen but slightly oblique. As such a viewing angle compensating retardation plate, for example, a retardation plate, an alignment film such as a liquid crystal polymer, or a support in which an alignment layer such as a liquid crystal polymer is supported on a transparent base material can be used. A common retardation plate is a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film is biaxially stretched in the plane direction. Biaxially oriented polymer film with birefringence and biaxial stretching such as birefringent polymer or tilted oriented film, which is uniaxially stretched in the force and plane directions and also stretched in the thickness direction and has a controlled refractive index in the thickness direction. A film or the like is used. Examples of the obliquely oriented film include a film obtained by bonding a heat shrink film to a polymer film and subjecting the polymer film to a stretching treatment or a Z-shrink treatment under the action of the shrinkage force caused by heating, or a film obtained by obliquely orienting a liquid crystal polymer. And the like. As the raw material polymer for the retardation plate, the same polymer as that described for the retardation plate is used to prevent coloring and the like due to a change in the viewing angle based on the phase difference by the liquid crystal cell, and to improve the viewing angle for good visibility. Appropriate ones for the purpose of enlargement etc. can be used.

[0079] In addition, the alignment layer of liquid crystal polymer, particularly An optically compensatory retardation plate in which an optically anisotropic layer composed of a tilted alignment layer of a scotic liquid crystal polymer is supported by a triacetyl cellulose film can be preferably used.

 [0080] The polarizing plate obtained by laminating the polarizing plate and the brightness enhancement film is usually provided on the back side of the liquid crystal cell and used. Brightness-enhancing films exhibit the property of reflecting linearly polarized light with a predetermined polarization axis or circularly polarized light in a predetermined direction when natural light enters due to reflection from the backlight or the back side of a liquid crystal display device, etc., and transmitting other light. The polarizing plate in which the brightness enhancement film is laminated with the polarizing plate receives light from a light source such as a backlight to obtain transmitted light of a predetermined polarization state and reflects light other than the predetermined polarization state without transmitting the light. Is done. The light reflected on the surface of the brightness enhancement film is further inverted through a reflection layer or the like provided on the rear side thereof and re-entered on the brightness enhancement film, and a part or all of the light is transmitted as light of a predetermined polarization state. In addition to increasing the amount of light that passes through the brightness enhancement film by increasing the amount of light that can be used for liquid crystal display image display and the like by supplying polarized light that is difficult to absorb to the polarizer, the brightness can be improved. is there. That is, when light is incident through a polarizer on the back side of a liquid crystal cell with a backlight or the like without using a brightness enhancement film, light having a polarization direction that does not match the polarization axis of the polarizer is It is almost absorbed by the polarizer and does not pass through the polarizer. That is, although it varies depending on the characteristics of the polarizer used, about 50% of the light is absorbed by the polarizer, and the amount of light used for liquid crystal image display and the like is reduced, and the image becomes darker. The brightness enhancement film reflects light having a polarization direction that is absorbed by the polarizer on the brightness enhancement film without being incident on the polarizer, and further through a reflection layer or the like provided on the rear side thereof. Repeated inversion and re-injection into the brightness enhancement film, and only the polarized light whose polarization direction is reflected and inverted between the two so that it can pass through the polarizer is used as the brightness enhancement film. Since the light is transmitted to the polarizer and supplied to the polarizer, light from a backlight or the like can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

[0081] A diffusion plate may be provided between the brightness enhancement film and the above-mentioned reflection layer or the like. The light in the polarization state reflected by the brightness enhancement film goes to the reflection layer and the like, but the diffuser provided uniformly diffuses the passing light and at the same time eliminates the polarization state and becomes a non-polarized state. That is, the diffuser returns the polarized light to the original natural light state. This unpolarized state, The light in a natural light state is repeatedly directed to the reflection layer and the like, reflected through the reflection layer and the like, again passed through the diffusion plate and re-incident on the brightness enhancement film. By providing a diffuser between the brightness enhancement film and the reflective layer, etc., which returns the polarized light to the original natural light state, the brightness of the display screen is maintained while the brightness unevenness of the display screen is reduced. It can provide a uniform and bright screen. It is probable that by providing a powerful diffuser, the number of repetitions of the first incident light was increased moderately, and it was possible to provide a uniform bright display screen in combination with the diffuser function of the diffuser. .

 [0082] Examples of the brightness enhancing film include a multilayer thin film of a dielectric and a multilayer laminate of thin films having different refractive index anisotropies. Reflects either left-handed or right-handed circularly polarized light, and transmits other light, such as those exhibiting reflective characteristics, such as an alignment film of cholesteric liquid crystal polymer and an alignment liquid crystal layer supported on a film substrate. Any suitable material such as one exhibiting the characteristic described above can be used.

 Therefore, in the above-described brightness enhancement film that transmits linearly polarized light having a predetermined polarization axis, the transmitted light is directly incident on the polarization plate with the polarization axis aligned, whereby absorption loss due to the polarization plate is suppressed. While allowing the light to pass through efficiently. On the other hand, a brightness enhancement film that emits circularly polarized light, such as a cholesteric liquid crystal layer, can be directly incident on a polarizer.However, in order to suppress absorption loss, the circularly polarized light is linearly polarized through a phase difference plate. It is preferable that the light is converted into a polarizing plate. By using a 1Z4 wavelength plate as the retardation plate, circularly polarized light can be converted to linearly polarized light.

 [0084] A retardation plate functioning as a 1Z4 wavelength plate in a wide wavelength range such as a visible light region has, for example, a retardation layer functioning as a 1Z4 wavelength plate for light-colored light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by, for example, a method of superimposing a retardation layer shown, for example, a retardation layer functioning as a 1Z2 wavelength plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may have one or more retardation layer strengths.

[0085] The cholesteric liquid crystal layer also reflects circularly polarized light in a wide wavelength range such as a visible light region by using a combination of two or more layers having different reflection wavelengths and having an arrangement structure in which two or more layers are overlapped. And a circularly polarized light having a wide wavelength range can be obtained. [0086] Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers as in the above-mentioned polarized light separating type polarizing plate. Therefore, a reflective elliptically polarizing plate or a transflective elliptically polarizing plate obtained by combining the above-mentioned reflective polarizing plate, transflective polarizing plate and retardation plate may be used.

 [0087] An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method in which the optical film is laminated in advance in a manufacturing process of a liquid crystal display device or the like. In addition, it has the advantage of being superior in quality stability and assembling work, and can improve the manufacturing process of a liquid crystal display device and the like. Appropriate bonding means such as an adhesive layer can be used for lamination. In bonding the above-mentioned polarizing plate and other optical layers, their optical axes can be set at an appropriate angle depending on the intended retardation characteristics and the like.

 [0088] Each layer of the pressure-sensitive adhesive optical film of the present invention, such as the optical film and the pressure-sensitive adhesive layer, includes, for example, a salicylate compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt. It may have ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorbing agent such as a compound.

The adhesive optical film of the present invention can be preferably used for forming various image display devices such as a liquid crystal display device. The formation of the liquid crystal display device can be performed according to a conventional method. That is, a liquid crystal display device generally has a force formed by appropriately assembling components such as a liquid crystal cell, an adhesive optical film, and an illumination system as necessary and incorporating a drive circuit. Except for using the optical film according to the present invention, the present invention can conform to the conventional method without any particular limitation. As for the liquid crystal cell, any type such as TN type, STN type and π type can be used.

[0090] A suitable liquid crystal display device such as a liquid crystal display device having an adhesive optical film disposed on one or both sides of a liquid crystal cell, or a device having a backlight or a reflector in a lighting system can be formed. . In that case, the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array One or two or more layers of appropriate parts such as light sheets, light diffusion plates, and backlights can be placed at appropriate positions.

 [0091] 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 stacked on a transparent substrate to form a light emitting body (organic electroluminescent light emitting body). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer of a fluorescent organic solid force such as anthracene, or A structure having various combinations such as a laminate of such a light-emitting layer and an electron injection layer having a perylene derivative or a hole injection layer, a light-emitting layer, and an electron injection layer. Is known.

 [0092] In an organic EL display device, holes and electrons are injected into an organic light emitting layer by applying a voltage to a transparent electrode and a metal electrode, and energy generated by recombination of these holes and electrons is generated. Emits light on the principle that it excites a fluorescent substance and emits light when the excited fluorescent substance returns to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be expected from this, the current and the emission intensity show a strong ゝ non-linearity with rectification to the applied voltage.

 [0093] In an organic EL display device, at least one electrode must be transparent in order to extract light emitted from the organic light emitting layer, and is usually formed of a transparent conductor such as indium tin oxide (ITO). A transparent electrode is used as the anode. On the other hand, it is important to use a material with a small work function for the cathode in order to facilitate electron injection and increase the light emission efficiency, and metal electrodes such as Mg Ag and A1-Li are usually used.

 [0094] In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film when the thickness is about lOnm. Therefore, the organic light emitting layer transmits light almost completely, similarly to the transparent electrode. As a result, when the light is not emitted, the light enters the surface of the transparent substrate, passes through the transparent electrode and the organic light-emitting layer, and is reflected by the metal electrode. When viewed, the display surface of the OLED display looks like a mirror.

[0095] An organic electroluminescent luminous body comprising a transparent electrode on the front side of an organic luminescent layer that emits light by applying a voltage and a metal electrode on the back side of the organic luminescent layer is provided. In an organic EL display device including the same, a polarizing plate can be provided on the surface side of the transparent electrode, and a retardation plate can be provided between the transparent electrode and the polarizing plate.

[0096] Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, the polarizing effect has an effect of preventing a mirror surface of the metal electrode from being visually recognized from the outside. is there. In particular, if the phase difference plate is formed of a 1Z4 wavelength plate and the angle between the polarization directions of the polarizing plate and the phase difference plate is adjusted to π Ζ4, the mirror surface of the metal electrode can be completely shielded.

 That is, only linearly polarized light components of the external light incident on the organic EL display device are transmitted by the polarizing plate. This linearly polarized light is generally converted into elliptically polarized light by the phase difference plate, but becomes circularly polarized light when the phase difference plate is a 1Z4 wavelength plate and the angle between the polarization directions of the polarization plate and the phase difference plate is π / 4. .

 [0098] The circularly polarized light transmits through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, passes through the organic thin film, the transparent electrode, and the transparent substrate again, and is again converted into linearly polarized light by the retardation plate. Become. Since this linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it cannot pass through the polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

 Example

 [0099] Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. All parts and percentages in each example are based on weight. The methods for measuring the weight average molecular weight, absorbance, and gel fraction are as follows.

 [0100] [Measurement of weight average molecular weight]

 The weight-average molecular weights of the prepared polymers and oligomers were measured by GPC (gel permeation chromatography) and converted by standard polystyrene.

 GPC device: TOSOH, HLC-8120GPC

 Column: Up to 500,000 Mw, (GMHHR-H), (GMHHR-H) and (G2000HHR) were used in combination. For Mw 500,000 or more, (G7000HXL), (GMHXL) and (GMHXL) were used in combination.

 Flow rate: 0.8ml / mm

Concentration: 1. Og / 1 Injection volume: 100 1

Column temperature: 40 ° C

Eluent: THF

 [Measurement of absorbance, calculation of absorbance ratio]

Using an infrared spectrophotometer (PerkinElmer KK, SPECTRUM2000), the absorbance based on the C = C vibration of the chain transfer agent in the range of 780 × 20 cm- ¹ of the pressure-sensitive adhesive composition for optical film prepared, and 740 ± The absorbance based on the CH vibration of the polymer and oligomer in the range of 20 cm- ¹ was measured. The absorbance ratio was calculated by the following equation.

Absorbance ratio = (Absorbance based on C = C vibration of chain transfer agent in the range of 780 × 20 cm- ¹ ) Z (Absorbance based on CH vibration of polymer and oligomer in the range of 740 ± 20 cm- ¹ )

 (Measurement of gel fraction)

 About 0.1 lg of the cross-linked pressure-sensitive adhesive layer was taken, weighed, and measured for weight (W). Next, wrap this in a microporous tetrafluoroethylene membrane (membrane weight W) and add about 50 ml of acetic acid.

 2

After immersion in ethyl for 2 days, the soluble matter was extracted. Dry this and the total weight (W)

 3 was measured. From these measured values, the gel fraction (% by weight) of the pressure-sensitive adhesive layer was determined by the following equation.

Gel fraction (% by weight) = {(W-W) / W} X100

 3 2 1 Example 1

 (Preparation of acrylic polymer)

 97 parts of butyl acrylate, 3 parts of acrylic acid, 0.2 parts of 2,2-azobisisobutyrate-tolyl, and 100 parts of ethyl acetate were charged into a four-necked flask equipped with a nitrogen inlet tube and a condenser tube for 1 hour. After purging with nitrogen, a polymerization reaction was carried out at 60 ° C. for 7 hours while stirring under a nitrogen stream to obtain a solution of an acrylic polymer having a weight average molecular weight of 1.5 million.

(Preparation of acrylic oligomer)

In a four-necked flask equipped with a nitrogen inlet tube and a condenser tube, 100 parts of butyl acrylate, 1 part of methyl styrene dimer, 10 parts of 2,2-azobisisobutyral-tolyl, and 10 parts of ethyl acetate After introducing 0 parts and purging with nitrogen for 1 hour, a polymerization reaction was carried out at 70 ° C. for 3 hours while stirring under a nitrogen stream to obtain a solution of an acrylic oligomer (A) having a weight average molecular weight of 5000. (Preparation of pressure-sensitive adhesive composition for optical film)

 0.07 parts of the solution containing 100 parts of an acrylic polymer, the solution containing 20 parts of an acrylic oligomer (A), and an isocyanate-based crosslinking agent (Takenate D110N, manufactured by Mitsui Takeda Chemical Co., Ltd.) as a crosslinking agent And 0.02 parts of A-100 (Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent were uniformly mixed to prepare a pressure-sensitive adhesive composition for an optical film.

(Preparation of adhesive optical film)

 Apply the prepared pressure-sensitive adhesive composition to a 38 m-thick polyethylene terephthalate film that has been subjected to silicone release treatment so that the dried pressure-sensitive adhesive layer has a thickness of 20 / zm, and dry at 110 ° C for 5 minutes. 'Cross-linking was performed to form an adhesive layer. The pressure-sensitive adhesive layer was transferred to a polarizing plate and aged at room temperature (23 ° C.) for 5 days to obtain a pressure-sensitive adhesive optical film. The gel fraction of the pressure-sensitive adhesive layer was 50% by weight.

 Example 2

 (Preparation of acrylic polymer)

 A solution of an acrylic polymer was obtained in the same manner as in Example 1.

(Preparation of acrylic oligomer)

 In a four-necked flask equipped with a nitrogen inlet tube and a condenser tube, 100 parts of butyl acrylate, 10 parts of methyl styrene dimer, 1 part of 2,2-azobisisobuty-tolyl, and 100 parts of ethyl acetate were charged. After replacing with nitrogen for 1 hour, a polymerization reaction was carried out at 70 ° C. for 3 hours while stirring under a nitrogen stream to obtain a solution of an acrylic oligomer (B) having a weight average molecular weight of 5000. (Preparation of pressure-sensitive adhesive composition for optical film)

 An optical film was prepared in the same manner as in Example 1 except that the solution containing 20 parts of the acrylic oligomer (A) was replaced with the solution containing 5 parts of the acrylic oligomer (B). An adhesive composition was prepared.

(Preparation of adhesive optical film)

An adhesive optical film was obtained in the same manner as in Example 1 except that the above-mentioned adhesive composition for optical films was used. The gel fraction of the pressure-sensitive adhesive layer was 55% by weight. [0102] Example 3

 (Preparation of acrylic polymer)

 A solution of an acrylic polymer was obtained in the same manner as in Example 1.

 (Preparation of acrylic oligomer)

 A solution of the acrylic oligomer (B) was obtained in the same manner as in Example 2.

 (Preparation of pressure-sensitive adhesive composition for optical film)

 An optical film for an optical film was prepared in the same manner as in Example 1, except that the solution containing 20 parts of the acrylic oligomer (A) was replaced with the solution containing 10 parts of the acrylic oligomer (B). An adhesive composition was prepared.

 (Preparation of adhesive optical film)

 An adhesive optical film was obtained in the same manner as in Example 1 except that the above-mentioned pressure-sensitive adhesive composition for an optical film was used. The gel fraction of the pressure-sensitive adhesive layer was 53% by weight.

[0103] Comparative Example 1

 (Preparation of acrylic polymer)

 A solution of an acrylic polymer was obtained in the same manner as in Example 1.

 (Preparation of acrylic oligomer)

 A solution of the acrylic oligomer (B) was obtained in the same manner as in Example 2.

 (Preparation of pressure-sensitive adhesive composition for optical film)

 An optical film was prepared in the same manner as in Example 1 except that the solution containing 20 parts of the acrylic oligomer (A) was replaced with the solution containing 20 parts of the acrylic oligomer (A). An adhesive composition was prepared.

 (Preparation of adhesive optical film)

 An adhesive optical film was obtained in the same manner as in Example 1 except that the above-mentioned adhesive composition for optical films was used. The gel fraction of the pressure-sensitive adhesive layer was 50% by weight.

[0104] Comparative Example 2

 (Preparation of acrylic polymer)

 A solution of an acrylic polymer was obtained in the same manner as in Example 1.

(Preparation of acrylic oligomer) A solution of the acrylic oligomer (B) was obtained in the same manner as in Example 2.

 (Preparation of pressure-sensitive adhesive composition for optical film)

 An optical film for an optical film was prepared in the same manner as in Example 1 except that the solution containing 20 parts of the acrylic oligomer (A) was replaced with the solution containing 50 parts of the acrylic oligomer (B). An adhesive composition was prepared.

 (Preparation of adhesive optical film)

 An adhesive optical film was obtained in the same manner as in Example 1 except that the above-mentioned adhesive composition for optical films was used. The gel fraction of the pressure-sensitive adhesive layer was 47% by weight.

[0105] Comparative Example 3

 (Preparation of acrylic polymer)

 A solution of an acrylic polymer was obtained in the same manner as in Example 1.

 (Preparation of acrylic oligomer)

 A solution of the acrylic oligomer (B) was obtained in the same manner as in Example 2.

 (Preparation of pressure-sensitive adhesive composition for optical film)

 An optical film for an optical film was prepared in the same manner as in Example 1, except that the solution containing 20 parts of the acrylic oligomer (A) was replaced with the solution containing 100 parts of the acrylic oligomer (B). An adhesive composition was prepared.

 (Preparation of adhesive optical film)

 An adhesive optical film was obtained in the same manner as in Example 1 except that the above-mentioned adhesive composition for optical films was used. The gel fraction of the pressure-sensitive adhesive layer was 45% by weight.

The following evaluations were performed on the pressure-sensitive adhesive optical films (polarizing plates) obtained in Examples and Comparative Examples. The results are shown in Table 1.

<Evaluation of window frame-shaped unevenness>

The produced pressure-sensitive adhesive optical film was adhered to both sides of an alkali-free glass plate (0.7 mm thick) so as to be in a crossed Nicols state. Next, the sample was subjected to autoclave treatment at 50 ° C and 5 atm for 15 minutes, and the sample was completely adhered to obtain a sample. Thereafter, the sample was left for 1) at 120 or 2) at 80 ° C and 90% RH for 500 hours. Then, the occurrence state of the window frame-shaped unevenness of the polarizing plate was visually observed on a 10,000-power Nendera backlight, and evaluated according to the following criteria. 〇: No problem in practical use.

 Δ: This is not a problem in practical use, but slightly generates window frame-like unevenness.

 X: Practically problematic, and window frame-like unevenness has occurred.

[0108] <Evaluation of light leakage>

 The prepared pressure-sensitive adhesive optical film was adhered to both sides of a non-alkali glass plate (0.7 mm thick) so as to be in a crossed Nicols state. Next, the sample was subjected to autoclave treatment at 50 ° C and 5 atm for 15 minutes, and the sample was completely adhered to obtain a sample. Thereafter, the sample was left for 1) at 120 or 2) at 80 ° C and 90% RH for 500 hours. The occurrence of light leakage from the polarizing plate was visually observed on a 10,000 vender Ndera backlight, and evaluated according to the following criteria.

 〇: No problem in practical use.

 Δ: Not a problem in practical use, but slight light leakage occurs.

 X: A problem in practical use, and light leakage has occurred.

[0109] [Table 1]

Time Time Gogo Degree () () Absorption ratio 91200 Lily 800% 000CRH 5C 5AB X X

 〇 〇 〇 〇 〇 〇

 Window frame-shaped part shining Window frame-shaped shining heavy weight leakage () Mum () Lara

 Example 1

 Example 2

 Example 3 <l

 〇 比 Comparative ratio <1 I <l

 X

 Comparative ratio 2

 Comparative ratio 3

〇

 〇 1 〇 〇 〇

〇 〇 〇 X X X

o

 I o o o o

o I 1 1 I I

m σ

 o o o o o o

As is clear from Table 1, the pressure-sensitive adhesive optical film using the pressure-sensitive adhesive composition having an absorbance ratio of 0.3 or less (Example 13) was subjected to long-term severe environmental conditions (120 ° C 80 ° C 90% RH). ), There is no adverse effect on the liquid crystal display state, which does not cause window frame-shaped unevenness or light leakage on the optical film (polarizing plate). On the other hand, the viscosity using an adhesive composition having an absorbance ratio exceeding 0.3 The wearable optical film (Comparative Examples 13) has window frame-shaped unevenness due to long-term severe environmental conditions (120 ° C for 500 hours), which adversely affects the liquid crystal display.

 Industrial applicability

 The present invention relates to a pressure-sensitive adhesive composition for an optical film and a pressure-sensitive adhesive layer for an optical film formed by the pressure-sensitive adhesive composition for an optical film. The present invention also relates to an adhesive optical film having the adhesive layer, and to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP using the adhesive optical film. Examples of the optical film include a polarizing plate, a retardation plate, an optical compensation film, a brightness enhancement film, and a laminate of these.

Claims

The scope of the claims

[1] Weight-average molecular weight 500,000 (Meth) atarylate polymer having a molecular weight of 2.5 million, reactive carbon carbon (meta) atali having a weight-average molecular weight of 1,000 to 10,000 polymerized using a chain transfer agent having a double bond A pressure-sensitive adhesive composition containing a rate-based oligomer and a cross-linking agent, and wherein the content of the chain transfer agent in the composition is an absorbance ratio [(780 to 20 cm- ¹ ). C = absorbance based on C vibration) Z (absorbance based on CH vibration of the polymer and oligomer in the range of 740 × 20 cm- ¹ )]] of 0.3 or less. .

 [2] The chain transfer agent according to claim 1, wherein the chain transfer agent is at least one styrene-based chain transfer agent selected from the group consisting of α-methylstyrene, α-methylstyrene dimer, and α-methylstyrene trimer. An adhesive composition for an optical film.

 [3] An adhesive layer for an optical film formed by crosslinking the adhesive composition for an optical film according to claim 1 or 2.

 4. The pressure-sensitive adhesive layer for an optical film according to claim 3, wherein the gel fraction is 30 to 80% by weight.

 [5] An adhesive optical film, wherein the optical film adhesive layer according to claim 3 or 4 is formed on one or both surfaces of the optical film.

[6] An image display device using at least one pressure-sensitive adhesive optical film according to claim 5.