JP5758261B2 - Optical pressure-sensitive adhesive, pressure-sensitive adhesive layer, optical film, and image display device - Google Patents

Description

  The present invention relates to an optical pressure-sensitive adhesive, an optical pressure-sensitive adhesive layer, and an optical film. Further, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, a CRT, or a PDP using the optical film.

  In the liquid crystal display device, it is indispensable to dispose polarizing elements on both sides of the liquid crystal cell because of its image forming method, and generally a polarizing plate is attached. In addition to polarizing plates, various optical elements have been used for liquid crystal panels in order to improve the display quality of displays. For example, a retardation plate for preventing coloring, a viewing angle widening film for improving the viewing angle of a liquid crystal display, and a brightness enhancement film for increasing the contrast of the display are used. These films are collectively called optical films.

  When the optical film is attached to the liquid crystal cell, an adhesive is usually used. In addition, the adhesive between the optical film and the liquid crystal cell and the optical film is usually in close contact with each other using an adhesive to reduce the loss of light. In such a case, the adhesive is generally an optical film provided in advance as an adhesive layer on one side of the optical film because it has a merit that a drying step is not required to fix the optical film. Used for.

  Necessary characteristics required for the pressure-sensitive adhesive include that when the optical film is bonded to the surface of the liquid crystal panel, the optical film is liquid crystal even in the case where the bonding position is wrong or a foreign object is caught in the bonding surface. It can be peeled off from the panel surface without any adhesive residue, and can be pasted (reworked) again, and there should be no problems caused by adhesives for durability tests such as heating and humidification normally performed as environmental promotion tests. Is mentioned.

  Further, liquid crystal display devices are required to have a good image appearance, and liquid crystal display devices are required to have high contrast related to white display and black display. Various members have been developed to increase the contrast of liquid crystal display devices. Therefore, it is required that members used in the liquid crystal display device, for example, the pressure-sensitive adhesive layer, do not hinder high contrast.

  In order not to inhibit the increase in contrast, it is desirable that the member used in the liquid crystal display device does not cause depolarization. In particular, in a liquid crystal display device, a member on the inner side of two polarizing plates (transparent protective film on the liquid crystal cell side, a pressure-sensitive adhesive layer, a liquid crystal cell in the polarizing plate) disposed on both sides of the liquid crystal cell via an adhesive layer Is required not to cause depolarization.

  Moreover, what used the block copolymer (block copolymer) as an adhesive and an adhesive agent used for an optical film is proposed (refer patent documents 1-3). These pressure-sensitive adhesives can improve durability under severe temperature and humidity conditions by using a block copolymer.

Special table 2008-508394 gazette International Publication No. 2008/065982 Pamphlet Japanese Patent Laid-Open No. 7-82542

  However, it has been confirmed that the pressure-sensitive adhesive using the block copolymer has a problem that depolarization (contrast reduction) occurs in the study for adaptation and practical application to a high-contrast liquid crystal display device.

  The cause of the depolarization is that these adhesives form a domain structure by microphase separation inside, and the depolarization is caused by scattering due to refraction / reflection at the domain interface. However, the pressure-sensitive adhesive using a block polymer has a feature of excellent durability, but depolarization (contrast reduction) occurs, and it is difficult to apply it to a high-contrast liquid crystal display device.

  In Patent Documents 1 to 3, although a block copolymer is proposed from the viewpoint of durability, there is no disclosure regarding depolarization and no specific disclosure to a high-contrast liquid crystal display device. Currently.

  Therefore, the present invention is a pressure-sensitive adhesive and pressure-sensitive adhesive that can be used in optical applications that are excellent in durability under heating and humidification conditions and adhesive properties, and that can prevent depolarization and suppress a decrease in polarization degree. An object is to provide an agent layer, an optical film having the pressure-sensitive adhesive layer, and an image display device using the optical film.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the following optical pressure-sensitive adhesive, and have completed the present invention.

  That is, the optical pressure-sensitive adhesive of the present invention is a polymer composed of two or more types of monomers, and the monomers form two or more different blocks in the polymer, and the blocks are homopolymers, and / Or formed from a copolymer composed of two or more monomers, wherein the refractive index difference between the blocks is 0.015 or less.

  The optical pressure-sensitive adhesive of the present invention is a block in which at least one of the two or more different blocks is composed of two or more monomers, and the two or more monomers are the two or more types of monomers. Monomers that have a higher refractive index than those other than the block composed of two or more monomers and monomers that have a lower refractive index when each monomer forms a homopolymer. It is preferable to have at least one of each.

  In the optical pressure-sensitive adhesive of the present invention, the glass transition temperature of at least one of the blocks is preferably 90 ° C. or higher, and the glass transition temperature of other blocks is preferably 0 ° C. or lower.

  In the optical pressure-sensitive adhesive of the present invention, the polymer is preferably at least one copolymer selected from the group consisting of a linear type, a star shape, and a comb shape.

  In the optical pressure-sensitive adhesive of the present invention, the polymer preferably has a weight average molecular weight of 10,000 to 300,000.

  In the optical pressure-sensitive adhesive of the present invention, the polymer is preferably a (meth) acrylic acid ester-based polymer.

  The optical pressure-sensitive adhesive of the present invention preferably contains an isocyanate compound.

  The optical pressure-sensitive adhesive of the present invention preferably contains a silane coupling agent.

  The optical pressure-sensitive adhesive layer of the present invention is preferably formed from the optical pressure-sensitive adhesive layer.

  The optical film of the present invention preferably has the pressure-sensitive adhesive layer.

  In the optical film of the present invention, the pressure-sensitive adhesive layer is preferably formed on a substrate via an undercoat layer.

  The image display device of the present invention preferably uses the optical film.

  The image display device of the present invention is an image display device having the optical film, a polarizer, and a cell, and the pressure-sensitive adhesive layer of the optical film is disposed on the cell side with respect to the polarizer. Is preferred.

  The optical pressure-sensitive adhesive of the present invention is a polymer composed of two or more monomers, and the monomer forms two or more different blocks in the polymer, and the block is a homopolymer, and / or Alternatively, it is formed from a copolymer composed of two or more monomers, and by suppressing the refractive index difference between the blocks to a specific range, scattering due to the phase separation structure formed in the pressure-sensitive adhesive is eliminated. As a result, the decrease in the degree of polarization is suppressed, and the decrease in contrast is suppressed even when used in applications where a high degree of polarization is required. Thereby, even under heating and humidification conditions, an adhesive having excellent durability and adhesive properties can be obtained, and it can be applied to a high-contrast liquid crystal display device, which is useful.

  Below, each structure of the optical adhesive of this invention, the optical adhesive layer, and an optical film is demonstrated in detail. Further, an image display device using the optical film will be described.

  The optical pressure-sensitive adhesive of the present invention is a polymer composed of two or more types of monomers, and the monomers form two or more different blocks in the polymer, and the blocks are homopolymers (homopolymers). ) And / or a copolymer (copolymer) composed of two or more monomers, and the refractive index difference between the blocks is 0.015 or less, preferably 0.012 or less. More preferably, it is 0.09 or less. The refractive index difference between the blocks is 0.015 or less, that is, the refractive index difference between the blocks is suppressed to be small, resulting in refraction / reflection due to the phase separation structure formed in the adhesive. This eliminates the scattering caused by the light, thereby preventing the depolarization, suppressing the decrease in the degree of polarization, and reducing the contrast even when used for applications requiring a high degree of polarization (such as TV). This is a preferred embodiment.

  The optical pressure-sensitive adhesive of the present invention is a block in which at least one of the two or more different blocks is composed of two or more monomers, and the two or more monomers are When each of the above monomers forms a homopolymer, the refractive index is higher than the refractive index of the block other than the block composed of the two or more monomers, and the refractive index is small. It is preferable that each has at least one monomer. By designing the blocks with different refractive indexes so that other blocks are sandwiched, the refractive index difference can be easily kept small, not only with low depolarization, but especially under heating and humidification conditions. It is excellent in durability and useful.

  The refractive index of the block can be prepared based on the refractive index of the monomer contained in the block and the ratio (composition ratio) of the monomer. If the monomer structures are similar, the monomer Since the refractive index of these tends to be similar, it can be adjusted as appropriate.

  The polymer is formed of two or more different blocks. For example, as the polymer, a linear block copolymer composed of these blocks (simply a block copolymer, a linear block copolymer, a linear block polymer, etc.) And a graft type block copolymer (sometimes simply referred to as a graft block copolymer, a graft polymer, or a comb copolymer). Specifically, when the at least one block is indicated as A, and different blocks other than the block are indicated as B and C, respectively, as the linear block copolymer, for example, a diblock copolymer represented by AB A triblock copolymer represented by ABA, BAB, a tetrablock copolymer, ABCA, a combination of A and B, and the like. Examples of the graft type block copolymer include those having A or B as a main chain and a block different from the main chain as a side chain. In addition, when each block, such as A, B, and C, is composed of two or more types of monomers, each block may be composed of a random copolymer, an alternating copolymer, a periodic copolymer, or the like.

  Among the linear block copolymers and graft block copolymers, a linear block copolymer is more preferable from the viewpoint of easy control of glass transition temperature (Tg) and molecular weight, and among linear block copolymers, The use of a linear triblock copolymer represented by A-B-A (or B-A-B) is particularly preferred from the viewpoint of easily controlling the adhesive properties and bulk physical properties.

  In the optical pressure-sensitive adhesive of the present invention, the glass transition temperature of at least one of the blocks is preferably 90 ° C. or higher, and the glass transition temperature of other blocks is preferably 0 ° C. or lower. By using a polymer containing these blocks, a pressure-sensitive adhesive (layer) excellent in adhesive properties and durability can be obtained even under heating and humidification conditions, which is useful.

  Of the blocks, the glass transition temperature (Tg) of the at least one block is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, and particularly preferably 110 ° C. or higher. When the Tg is 90 ° C. or higher, an appropriate cohesive force can be imparted to the pressure-sensitive adhesive (layer) at a normal use temperature, and sufficient under heating (high temperature) and humidification (high humidity) conditions. Can exhibit excellent adhesive properties and durability, and is useful without causing problems such as foaming and peeling.

  Among the blocks, the glass transition temperature (Tg) of the other blocks is preferably 0 ° C. or lower, more preferably −20 ° C. or lower, and particularly preferably −30 ° C. or lower. preferable. The Tg is usually −70 ° C. or higher. When the Tg is 0 ° C. or lower, the pressure-sensitive adhesive (layer) can exhibit appropriate wettability, flexibility, and necessary adhesion (adhesion) force to the adherend. Further, when Tg is −20 ° C. or lower, a more preferable aspect is obtained in that durability under low temperature conditions is excellent.

  In the optical pressure-sensitive adhesive of the present invention, the polymer is preferably at least one copolymer selected from the group consisting of a linear type, a star shape, and a comb shape. By using the copolymer having these shapes, the form of the phase separation structure formed in the pressure-sensitive adhesive layer is a preferable embodiment for suppressing the decrease in the degree of polarization.

Specific examples of the linear block copolymer include the following structure (1). In addition, the solid line shown below and a broken line show a different block.

Specific examples of the star-shaped block copolymer include the following structure (2).

Specific examples of the comb block copolymer include the following structure (3).

  In the optical pressure-sensitive adhesive of the present invention, the weight average molecular weight (Mw) of the polymer is preferably 10,000 to 300,000, more preferably 30,000 to 250,000, and particularly preferably 40,000 to 200,000. When the molecular weight is less than 10,000, the cohesive force of the pressure-sensitive adhesive is insufficient, and when the optical film is bonded and used, the pressure-sensitive adhesive properties and durability are inferior. On the other hand, when the molecular weight exceeds 300,000, the solution viscosity becomes too high, and there is a possibility that the coating cannot be performed, and productivity is lowered.

  The optical pressure-sensitive adhesive of the present invention contains the polymer, and can be used without particular limitation as long as it can provide a difference in refractive index between the blocks, but for example, the polymer is a (meth) acrylic polymer, Vinyl polymers, conjugated diene polymers, olefin polymers, and lactone polymers can be used. Among them, (meth) acrylic polymers are preferable, and (meth) acrylic acid ester polymers are particularly transparent and mass-productive. It is preferable at the point which is excellent in.

  Examples of the monomer constituting the (meth) acrylic acid ester-based polymer include (meth) acrylic acid alkyl ester, and there is no particular limitation as long as the refractive index of the block obtained from the monomer can be adjusted. Can be used. For example, examples of the (meth) acrylic acid alkyl ester include (meth) acrylic acid alkyl esters having an alkyl group having 1 to 18 carbon atoms. The (meth) acrylic acid alkyl ester refers to an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester, and has the same meaning as (meth) in the present invention. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylate n -Hexyl, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, etc. Examples include (meth) acrylic acid alkyl esters. These can be used alone or in combination of two or more.

  Moreover, as long as it is in the range which can adjust the refractive index of a block, you may include other monomers other than the said (meth) acrylic-acid alkylester. Examples of the other monomer include methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, and 2- (meth) acrylic acid 2- (Meth) acrylic acid ester having a functional group such as aminoethyl, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate; (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, etc. Vinyl monomers having a carboxyl group; vinyl monomers having an amide group such as (meth) acrylamide; aromatic vinyl monomers such as styrene, α-methylstyrene and p-methylstyrene; conjugated dienes such as butadiene and isoprene Monomer: Olefin such as ethylene and propylene Nomar; .epsilon.-caprolactone, lactone-based monomers such as valerolactone. These may be used alone or in combination of two or more.

  For example, a combination of n-butyl acrylate (refractive index: 1.466, Tg: −54 ° C.) and t-butyl methacrylate (refractive index: 1.464, Tg: 118 ° C.) can provide a desired difference in refractive index. Since it is easy to adjust, using is a preferable aspect.

  A method for producing the polymer (for example, a linear, star-shaped, or comb-shaped copolymer) is not particularly limited, and a method according to a known method can be employed. In general, as a method for obtaining a block copolymer (block copolymer) having a narrow molecular weight distribution, a method of living polymerizing monomers as constituent units is employed. Such living polymerization techniques include, for example, a method of polymerizing an organic rare earth metal complex as a polymerization initiator (Japanese Patent Laid-Open No. 6-93060), an alkali metal or an alkaline earth metal using an organic alkali metal compound as a polymerization initiator. Anionic polymerization in the presence of mineral salts such as salts (see Japanese Patent Publication No. 7-25859), anionic polymerization in the presence of an organoaluminum compound using an organic alkali metal compound as a polymerization initiator (Japanese Patent Laid-Open No. Hei 11- 335432), atom transfer radical polymerization method (ATRP) (Macromol. Chem. Phys. 201, 1108 to 1114 (2000)), etc. Further, as a method for obtaining a graft copolymer, Japanese Patent No. 4228026 is disclosed. And the like.

  Among the above production methods, in the case of an anionic polymerization method using an organoaluminum compound as a catalyst, there is little deactivation during the polymerization, so there is little mixing of the deactivating component homopolymer. High transparency. Moreover, since the polymerization conversion rate of a monomer is high, there are few residual monomers in a product, and when using it as an adhesive for optical films, generation | occurrence | production of the bubble after bonding can be suppressed. Furthermore, the molecular structure of the polymer is highly syndiotactic and has the effect of enhancing durability when used in an optical film adhesive. And because living polymerization is possible under relatively mild temperature conditions, it is possible to reduce the environmental burden (mainly the power required for the refrigerator to control the polymerization temperature) for industrial production. There is.

  The optical pressure-sensitive adhesive of the present invention can contain an isocyanate compound as an additive. Inclusion of the isocyanate compound can be expected to improve the adhesion to the optical member. Isocyanate compounds are particularly preferably used. These compounds may be used alone or in combination of two or more.

  Diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diisocyanate adducts modified with various polyols, isocyanurate rings, burettes, and allophanates are formed as the isocyanate compounds. The polyisocyanate compound etc. which were made to be mentioned.

  When an aromatic isocyanate compound is used together with a peroxide, the pressure-sensitive adhesive layer after curing may be colored. Therefore, in applications where transparency is required, the isocyanate compound is preferably an aliphatic or alicyclic isocyanate compound.

  The compounding amount of the isocyanate compound is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the polymer with respect to 100 parts by weight of the polymer. If it is in the said range, adhesiveness with a base material becomes favorable and is preferable.

  Moreover, the optical adhesive of this invention can contain a silane coupling agent as an additive. By containing a silane coupling agent, the durability of the pressure-sensitive adhesive (layer) can be improved.

  Examples of the silane coupling agent include silane cups having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane. Ring agent; 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N -Amino group-containing silane coupling agents such as (1,3-dimethylbutylidene) propylamine; (meth) acryl group-containing silane couplings such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane Agent; 3-isocyanate Isocyanate group-containing silane coupling agents such as Russia pills triethoxysilane; 3-chloropropyl trimethoxysilane; and acetoacetyl group-containing trimethoxysilane and the like.

  The silane coupling agent may be used alone or as a mixture of two or more. The total amount of the silane coupling agent is 100 parts by weight of the polymer. On the other hand, it is 0.01-5 weight part, Preferably it is 0.05-1 weight part. When the amount is less than 0.01 parts by weight, it is difficult to improve the durability. On the other hand, when the amount exceeds 5 parts by weight, the adhesion (adhesion) force to the liquid crystal cell tends to increase and the removability is improved. Inferior.

  In addition, various additives can also be used suitably for the adhesive which forms the optical adhesive layer of this invention in the range which does not deviate from the objective of this invention. Examples of the additive include tackifiers, plasticizers, glass fibers, glass beads, metal powders, other inorganic powders, fillers, pigments, colorants, fillers, antioxidants, ultraviolet absorbers, and the like. be able to. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility.

  The optical pressure-sensitive adhesive layer of the present invention is preferably formed from the optical pressure-sensitive adhesive layer. By using the optical pressure-sensitive adhesive, a decrease in the degree of polarization is suppressed, and when the optical pressure-sensitive adhesive layer is used for applications requiring a high degree of polarization, there is no reduction in contrast, which is useful. Moreover, even under heating / humidifying conditions, sufficient adhesive strength can be exhibited (adhesive properties), and an excellent durability can be obtained.

  The method for forming the optical pressure-sensitive adhesive layer of the present invention is not particularly limited, and a known formation method can be used. For example, a method of applying and drying a pressure-sensitive adhesive (solution), a mold release provided with a pressure-sensitive adhesive layer Examples thereof include a method of transferring with a sheet. As a coating method, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, or a spray method can be adopted.

  As the constituent material of the release sheet, appropriate thin leaf such as paper, polyethylene, polypropylene, synthetic resin film such as polyethylene terephthalate, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminates thereof, etc. Examples include the body. The surface of the release sheet may be subjected to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment as necessary in order to enhance the peelability from the pressure-sensitive adhesive layer.

  The optical film of the present invention preferably has the pressure-sensitive adhesive layer, and more preferably, the pressure-sensitive adhesive layer is formed on a substrate via an undercoat layer. The optical film corresponds to an optical film with a pressure-sensitive adhesive layer, and by using the pressure-sensitive adhesive layer, without causing a decrease in the degree of polarization (low depolarization), the pressure-sensitive adhesive properties and durability are good, This is a preferred embodiment. Further, by providing the pressure-sensitive adhesive layer via an undercoat agent, the adhesiveness with the base material is improved, and defects during processing can be reduced.

  The undercoat layer can be formed with an undercoat containing polymers or the like. The polymer material is preferably a material that exhibits good adhesion to both the pressure-sensitive adhesive layer and the optical film (for example, a liquid crystal optical compensation layer) and forms a film having excellent cohesive strength.

  Examples of the polymers include polyurethane resins, polyester resins, and polymers containing an amino group in the molecule. The polymer may be used in any of a solvent-soluble type, a water-dispersed type, and a water-soluble type. For example, water-soluble polyurethane, water-soluble polyester, water-soluble polyamide, etc. and water-dispersible resins (ethylene-vinyl acetate emulsion, (meth) acrylic emulsion, etc.) can be mentioned. The water-dispersed type is obtained by emulsifying various resins such as polyurethane, polyester and polyamide using an emulsifier, or by introducing an anionic group, a cationic group or a nonionic group of a water-dispersible hydrophilic group into the resin. The self-emulsified product can be used. Moreover, an ionic polymer complex can be used.

  In addition to the above-described polymers, the undercoat layer may be appropriately used with various additives such as an antioxidant and a crosslinking agent as necessary and within a range not departing from the object of the present invention. it can.

  The undercoat layer is formed, for example, by applying and drying a solution of the undercoat containing the polymers and the antioxidant using a coating method such as a coating method, a dipping method, or a spray method to form an undercoat layer. Let The thickness of the undercoat layer is preferably about 10 to 5000 nm, more preferably in the range of 50 to 500 nm. When the thickness of the undercoat layer is reduced, it does not have bulk properties, does not exhibit sufficient strength, and sufficient adhesion may not be obtained. Moreover, when too thick, there exists a possibility of causing the fall of an optical characteristic.

  An antistatic agent can also be used in the optical film in order to impart antistatic properties. The antistatic agent can be contained in each layer, and an antistatic layer can be separately formed. Antistatic agents include ionic surfactant systems; conductive polymer systems such as polyaniline, polythiophene, polypyrrole, and polyquinoxaline; metal oxide systems such as tin oxide, antimony oxide, and indium oxide. From the viewpoint of appearance, antistatic effect, and stability during heating and humidification, a conductive polymer system is preferably used. Among these, water-soluble conductive polymers such as polyaniline and polythiophene or water-dispersible conductive polymers are particularly preferably used. This is preferable in the case where a water-soluble conductive polymer or a water-dispersible conductive polymer is used as a material for forming the antistatic layer from the viewpoint of suppressing deterioration of the optical film substrate due to an organic solvent during the coating process.

  Examples of the optical film include various types. Examples of the optical film include a polarizing plate, a retardation plate, an optical compensation film, a brightness enhancement film, and those in which these are laminated.

  Examples of the optical film of the present invention include an optical film having an optical compensation layer on one side of a base material (transparent base film).

  Various transparent materials can be used as the substrate (transparent substrate film). For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Polymer blends and the like can also be cited as examples of polymers forming the transparent substrate film.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing an unsubstituted phenyl and a thermoplastic resin having a nitrile group. Specific examples include a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used.

  The thickness of the transparent substrate film can be appropriately determined, but is generally about 1 to 500 μm from the viewpoints of workability such as strength and handleability, and thin film properties. In particular, 5 to 200 μm is preferable.

  Moreover, it is preferable that the said transparent base film is as colored as possible. Therefore, Rth = (nx−nz) · d (where nx is the refractive index in the slow axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a direction retardation of −90 nm to +75 nm is preferably used. By using a film having a retardation value (Rth) in the thickness direction of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the transparent substrate film can be almost eliminated. The thickness direction retardation (Rth) is more preferably -80 nm to +60 nm, and particularly preferably -70 nm to +45 nm.

  The transparent substrate film is preferably a cellulose polymer such as triacetyl cellulose or a norbornene polymer from the viewpoints of polarization characteristics and durability. In particular, a cellulose polymer such as triacetylcellulose is preferable.

  Moreover, as an optical film of this invention, the thing by which a polarizer and then a transparent protective film are laminated | stacked on the single side | surface of the transparent base film of the side in which a liquid crystal optical compensation layer is not formed can be used, for example. Moreover, a polarizer can also be bonded and used for a transparent base film using an adhesive agent. In addition, a transparent base film can also serve as the transparent protective film of a polarizer, and the polarizing plate which has a transparent protective film on the single side | surface or both surfaces of a polarizer can also be laminated | stacked on a transparent base film.

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 0.5 to 50 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. . If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

  As a material for forming the transparent protective film provided on one side or both sides of the polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. The transparent protective film can use the same material as the transparent substrate film. The same applies to the thickness.

  The transparent substrate film and the transparent protective film may use the same polymer material or different polymer materials.

  The polarizer, the transparent substrate film, and the transparent protective film are usually in close contact with each other through an aqueous 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, a water-based polyurethane, and a water-based polyester. In addition, in bonding of a polarizer, a transparent base film, and a transparent protective film, an activation process can be performed to a transparent base film and a transparent protective film. Various methods can be employed for the activation treatment, for example, saponification treatment, corona treatment, low-pressure UV treatment, plasma treatment, or the like. The activation treatment is effective particularly when the transparent substrate film is triacetyl cellulose, norbornene resin, polycarbonate, polyolefin resin, or the like.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare.

  In addition to the optical film having the polarizing plate laminated thereon, the optical film of the present invention can be used for forming an image display device such as a liquid crystal display device, and an optical layer can be laminated thereon. For example, an optical layer that may be used for forming a liquid crystal display device such as a reflection plate, an anti-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a brightness enhancement film. Can be mentioned. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with the target phase difference characteristic.

  The image display device of the present invention preferably uses the optical film. Since the optical film uses the pressure-sensitive adhesive layer, it can suppress a decrease in the degree of polarization and maintain a high contrast, and is preferably used for manufacturing various image display devices such as a liquid crystal display device. Can do. In addition, manufacture of image display apparatuses, such as the said liquid crystal display device, can be performed according to the past. That is, the liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell (also simply referred to as a cell), an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the optical film by this invention, It can manufacture according to the former. As the liquid crystal cell, an arbitrary type such as a VA type or an IPS type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an optical film is arranged on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination 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 single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Moreover, the image display device of the present invention is an image display device having the optical film, a polarizer, and a cell (liquid crystal cell), wherein the adhesive layer of the optical film is closer to the cell than the polarizer. It is preferable that it is arrange | positioned. By using the pressure-sensitive adhesive layer on the cell side (inner side) with respect to the polarizer, the adhesive property and durability are improved, and the low depolarization property works most effectively, which is a preferred embodiment.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight.

  The copolymer (copolymer) used in Examples and Comparative Examples was obtained by the following synthesis examples using chemicals dried and purified by a conventional method. At that time, the weight average molecular weight and composition of the obtained copolymer were measured by the following methods. Moreover, about the optical film obtained by the Example and the comparative example, the refractive index of each block, a glass transition temperature (Tg), the analysis of a depolarization value, the analysis of a contrast, the durability test under a heating or humidification condition The evaluation was carried out by the following method. The composition and structure are shown in Table 1, and the evaluation results are shown in Table 2.

<Measurement of weight average molecular weight (Mw) by gel permeation chromatography (GPC)>
Apparatus: Tosoh gel permeation chromatograph (HLC-8120GPC)
Column: TSKgel G7000HXL + GMHXL + GMHXL manufactured by Tosoh Corporation
Eluent: Tetrahydrofuran (THF)
Eluent flow rate: 1.0 ml / min Column temperature: 40 ° C
Detection method: differential refractive index (RI)
Calibration curve: Prepared using standard polystyrene Measurement procedure: The sample was dissolved in THF to 0.1% by weight and allowed to stand for 1 day, followed by filtration using a 0.45 μm membrane filter, and the GPC of the filtrate. Measurements were made.

<Calculation of glass transition temperature (Tg)>
The glass transition temperature is a theoretical value calculated using the formula of FOX from the Tg when the monomer used for the production of the copolymer is polymerized as a homopolymer and the ratio of each monomer.
The Tg of the homopolymer is an extrapolation start temperature (Tgi) in a curve obtained by DSC measurement using a DSC measuring device (DSC-822) manufactured by Mettler at a temperature increase rate of 10 ° C./min. It was obtained by calculating.

<Calculation of refractive index>
The refractive index is a theoretical value calculated from the refractive index when the monomer used for the production of the copolymer is polymerized as a homopolymer and the ratio of each monomer.
The refractive index of the homopolymer is a value measured at a wavelength of 589.3 of a sodium lamp at 23 ° C. using an Abbe refractometer DR-M2 manufactured by Atago Co., Ltd.

<Decrease in polarization degree: Depolarization value>
The polarization degree of the polarizing plate and the polarizing plate with the adhesive layer was measured using a spectrophotometer with an integrating sphere (V7100 manufactured by JASCO Corporation). The degree of polarization refers to the minimum transmittance (K ₂ ) measured by setting the transmission axis of the polarizing plate or the adhesive polarizing plate in a direction perpendicular to the plane of vibration of the polarized light from the prism, and the polarizing plate or the adhesive polarizing plate. The maximum transmittance (K ₁ ) measured by rotating the plate 90 degrees is obtained by applying to the following equation.
Polarization degree (%) = {(K ₂ −K ₁ ) / (K ₂ + K ₁ )} × 100
Each transmittance is represented by a Y value obtained by correcting the visibility with a two-degree field of view (C light source) of JIS Z8701, with 100% of the completely polarized light obtained through the Granteller prism polarizer as 100%. The polarization degree (P1) of the polarizing plate measured above and the polarization degree (P2) of the pressure-sensitive adhesive polarizing plate were calculated, and the difference (P2−P1) between these measured values was calculated. did.
The depolarization value (decrease in polarization degree) is preferably 0.016 or less and more preferably 0.015 or less. If it exceeds 0.016, the contrast is lowered, which is not preferable.

<Evaluation of contrast>
The contrast was evaluated based on the following criteria.
When the decrease in the degree of polarization is 0.010 or less, ◎.
When the decrease in the degree of polarization is more than 0.010 and 0.014 or less, it is good.
When the decrease in the degree of polarization exceeds 0.014 and is 0.016 or less, Δ.
When the decrease in the degree of polarization exceeds 0.016, x.

<Durability>
(I) Heat durability (80 ° C.) evaluation apparatus: ESPEC constant temperature and humidity tester Test conditions: 80 ° C. × 500 hours (test temperature × test time)
Sample: optical film with adhesive layer (polarizing plate with adhesive layer)
Sample size: 250mm x 300mm
Non-alkali glass: Corning non-alkali glass Eagle-XG
Autoclave treatment: 5 atm × 50 ° C. × 15 minutes An optical film with an adhesive layer prepared in Examples and Comparative Examples was bonded to non-alkali glass, then autoclaved, and further subjected to constant temperature and humidity as a durability test. It put into the testing machine and the state of the polarizing plate which comprises the optical film with an adhesive layer 500 hours after was confirmed.

(Ii) Evaluation of heat durability (90 ° C.) Evaluation was made in the same manner as in the above (i) except that the test temperature was changed to 90 ° C.

(Iii) Humidification durability (60 ° C. × 90% RH) evaluation The evaluation was performed in the same manner as in the above (i) except that the test temperature was changed to 60 ° C. and the humidity was adjusted to 90% RH.

In addition, evaluation of said (i)-(iii) was performed based on the following references | standards.
If no peeling is seen, ◎.
Yes, when the peel-off amount is 1 mm or less and does not cause a problem in actual use.
If the peel-off amount is 3 mm or less and cannot be used in demanding applications, it can be used in applications where high durability is not required.
When the peel-off amount exceeds 3 mm, peel-off occurs remarkably and it cannot be used as an optical adhesive, x.

(Polymer synthesis)
<Synthesis Example 1>
A 2 L three-necked flask was fitted with a three-way cock, and the inside was replaced with nitrogen. At room temperature, 868 g of toluene, 43.4 g of 1,2-dimethoxyethane, isobutylbis (2,6-di-t-butyl-4-methylphenoxy) ) 60.0 g of a toluene solution containing 40.2 mmol of aluminum was added, and 2.89 g of a mixed solution of cyclohexane and n-hexane containing 5.0 mmol of sec-butyllithium was further added. Subsequently, 30.5 g of t-butyl methacrylate (hereinafter abbreviated as tBMA) was added thereto and stirred at room temperature for 60 minutes. Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 240 g of n-butyl acrylate (hereinafter abbreviated as nBA) was added dropwise over 2 hours. Next, 30.5 g of tBMA was added, and after stirring overnight at room temperature, 3.50 g of methanol was added to stop the polymerization reaction. The obtained reaction solution was poured into methanol, and the precipitate was collected by filtration and dried to obtain 300 g of a linear triblock copolymer 1 of PtBMA-PnBA-PtBMA. PtBMA-PnBA-PtBMA represents poly-t-butyl methacrylate-poly-n-butyl acrylate-poly-t-butyl methacrylate. As a result of the GPC measurement, the copolymer 1 had a weight average molecular weight (Mw) of 73,000.

<Synthesis Example 2>
PtBMA-PMeOEA-PtBMA linear triblock copolymer 2 was obtained in the same manner as in Synthesis Example 1 except that 2-methoxyethyl acrylate (MeOEA) was used instead of nBA in Synthesis Example 1.

<Synthesis Example 3>
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer, 466 g of toluene, 240 g of isooctyl acrylate (hereinafter IOA), and 0.4 g of 2,2′-azobisisobutyronitrile are placed at room temperature. After performing nitrogen substitution, the temperature was raised to 55 ° C. and a polymerization reaction was carried out for 6 hours to obtain a polyisooctyl acrylate (PIOA) solution.
60 g of methyl methacrylate macromonomer (manufactured by Toa Gosei Chemical Co., Ltd.) having a methacryloyl group at the end group is added to 240 g of this solid content of PIOA, and normal solution polymerization is carried out using toluene as a solvent. A copolymer 3 of graft type block of IOA-side chain tBA was obtained.

<Synthesis Example 4>
In a 2 liter four-necked flask equipped with a stirrer, nitrogen introduction tube, dropping funnel, thermometer, and cooling tube, 120 g of methyl methacrylate (MMA) as the first (polymerizable) monomer and 95 g of ethyl acetate as the solvent In addition, the temperature was raised to 85 ° C. in a nitrogen atmosphere. After the internal temperature reached 85 ° C., 2 g of pentaerythritol tetrakisthioglycolate as a polyvalent mercaptan and 2,2′-azobis (2-methylbutyronitrile) as a radical polymerization initiator (Nippon Hydrazine Industries) Polymerization was started by adding 0.4 g of a trade name, ABN-E, hereinafter abbreviated as ABNE), and 15 g of ethyl acetate as a solvent. After 50 minutes and 80 minutes from the start of polymerization, 1.0 g of pentaerythritol tetrakisthioglycolate as a polyvalent mercaptan, 0.2 g of ABN-E as a radical polymerization initiator, and 10 g of ethyl acetate as a solvent were added for 140 minutes. Reacted. Subsequently, 480 g of n-hexyl methacrylate (nHMA) as a second (polymerizable) monomer and 460 g of ethyl acetate as a solvent were dropped from the dropping funnel over 2 hours. 30 minutes and 60 minutes after the completion of the dropping, 0.3 g of ABN-E as a radical polymerization initiator and 6 g of ethyl acetate as a solvent were added, respectively. Further, after 60 minutes, 0.7 g of azobisisobutyronitrile (manufactured by Nippon Hydrazine Kogyo Co., Ltd., trade name ABN-R) as a radical polymerization initiator and 15 g of ethyl acetate as a solvent were added. After further reaction for 2 hours under reflux, the reaction was stopped by cooling to room temperature. The obtained reaction solution was poured into methanol, and the precipitate was collected by filtration and dried to obtain a star block copolymer 4 comprising PMMA blocks (3) and PnHMA blocks (1).

<Synthesis Example 5>
A linear triblock copolymer 5 was obtained in the same manner as in Synthesis Example 1 except that n-dodecyl methacrylate (nDDMA) was used instead of nBA in Synthesis Example 1.

<Synthesis Example 6>
A linear triblock copolymer 6 was obtained in the same manner as in Synthesis Example 2 except that isobornyl methacrylate (IBMA) was used instead of tBMA in Synthesis Example 2.

<Synthesis Example 7>
A linear triblock copolymer 7 was obtained in the same manner as in Synthesis Example 5 except that isobornyl acrylate (IBA) was used instead of tBMA in Synthesis Example 5.

<Synthesis Example 8>
A 2 L three-necked flask was fitted with a three-way cock, and the inside was replaced with nitrogen. At room temperature, 868 g of toluene, 43.4 g of 1,2-dimethoxyethane, isobutylbis (2,6-di-t-butyl-4-methylphenoxy) ) 60.0 g of a toluene solution containing 40.2 mmol of aluminum was added, and 2.89 g of a mixed solution of cyclohexane and n-hexane containing 5.00 mmol of sec-butyllithium was further added. Subsequently, 30.5 g of tBMA was added thereto and stirred at room temperature for 60 minutes. Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 240 g of a mixture of nBA and 2-methoxyethyl acrylate (MeOEA) (mixing ratio 33/67) was added dropwise over 2 hours. Next, 30.5 g of tBMA was added, and after stirring overnight at room temperature, 3.50 g of methanol was added to stop the polymerization reaction. The obtained reaction solution was poured into methanol, and the precipitate was collected by filtration and dried to obtain 300 g of PtBA-P (nBA / MeOEA) -PtBA linear triblock copolymer 8.

<Synthesis Example 9>
A 2 L three-necked flask was fitted with a three-way cock, and the inside was replaced with nitrogen. At room temperature, 868 g of toluene, 43.4 g of 1,2-dimethoxyethane, isobutylbis (2,6-di-t-butyl-4-methylphenoxy) ) 60.0 g of a toluene solution containing 40.2 mmol of aluminum was added, and 2.89 g of a mixed solution of cyclohexane and n-hexane containing 5.00 mmol of sec-butyllithium was further added. Subsequently, 30.5 g of a mixture of MMA and tBMA (mixing ratio 8/92) was added thereto, followed by stirring at room temperature for 60 minutes. Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., and 240 g of nBA was added dropwise over 2 hours. Next, 30.5 g of a mixture of MMA and tBMA (mixing ratio 8/92) was added, and after stirring overnight at room temperature, 3.50 g of methanol was added to stop the polymerization reaction. The obtained reaction solution was poured into methanol, and the precipitate was collected by filtration and dried to obtain 300 g of a triblock copolymer 9 of P (MMA / tBMA) -PnBA-P (MMA / tBMA).

<Synthesis Example 10>
A 2 L three-necked flask was fitted with a three-way cock, and the inside was replaced with nitrogen. At room temperature, 868 g of toluene, 43.4 g of 1,2-dimethoxyethane, isobutylbis (2,6-di-t-butyl-4-methylphenoxy) ) 60.0 g of a toluene solution containing 40.2 mmol of aluminum was added, and 2.89 g of a mixed solution of cyclohexane and n-hexane containing 5.0 mmol of sec-butyllithium was further added. Subsequently, 30.5 g of a mixture of MMA and tBMA (18/82) was added thereto, followed by stirring at room temperature for 60 minutes. Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 120 g of a mixture of DDMA and MeOEA (27/73) was added dropwise over 2 hours, and 120 g of nBA was added dropwise over 2 hours. Next, MMA and 30.5 g of tBMA (18/82) were added thereto, and after stirring overnight at room temperature, 3.50 g of methanol was added to terminate the polymerization reaction. The obtained reaction solution was poured into methanol, and the precipitate was collected by filtration and dried to give P (MMA / tBMA) -P (DDMA / MeOEA) -PBA-P (MMA / tBMA) linear tetra. 300 g of block linear tetrablock copolymer 10 were obtained.

<Comparative Synthesis Example 1>
A triblock copolymer 11 was obtained in the same manner as in Synthesis Example 1 except that MMA was used instead of tBMA in Synthesis Example 1.

<Comparative Synthesis Example 2>
A triblock copolymer 12 was obtained in the same manner as in Synthesis Example 1 except that MMA was used instead of tBMA in Synthesis Example 2.

In addition, the refractive index and glass transition temperature (Tg) of each block in the copolymer (block) are as follows.
PMMA: Refractive index: 1.490, Tg: 105 ° C
PnBA: Refractive index: 1.466, Tg: -56 ° C
PnBMA: Refractive index: 1.383, Tg: 20 ° C
PMeOEA: Refractive index: 1.463, Tg: -50 ° C
PIOA: Refractive index: 1.470, Tg: -58 ° C
PnHMA: Refractive index: 1.481, Tg: -5 ° C
PDDMA: Refractive index: 1.447, Tg: -40 ° C
PIBMA: Refractive index: 1.474, Tg: 110 ° C
PIBA: Refractive index: 1.475, Tg: 94 ° C

[Example 1]
<Formation of adhesive layer>
After the copolymer 1 obtained in Synthesis Example 1 was dissolved in toluene to prepare a pressure-sensitive adhesive solution having a solid content concentration of 30% by weight, the pressure-sensitive adhesive solution was subjected to a release treatment on a polyester film (Mitsubishi Resin Co., Ltd.). On the separator made of MRF38 (made of 38 μm thickness), the pressure-sensitive adhesive layer after drying is applied to a thickness of 25 μm, heat-treated at 90 ° C. for 3 minutes to volatilize the solvent, Obtained.

<Optical film>
A 80 μm-thick polyvinyl alcohol film was stretched 3 times between rolls with different speed ratios while being dyed in an iodine solution of 0.3% concentration at 30 ° C. for 1 minute. Thereafter, the film was stretched until it was 6 times as long as it was immersed in an aqueous solution containing 60% at 4% concentration of boric acid and 10% concentration of potassium iodide for 0.5 minutes. Subsequently, it was immersed in an aqueous solution containing potassium iodide at 30 ° C. and 1.5% concentration for 10 seconds, washed, and then dried at 50 ° C. for 4 minutes to obtain a polarizer. A saponified 80 μm thick triacetyl cellulose film was bonded to both surfaces of the obtained polarizer with a polyvinyl adhesive to produce a polarizing plate as an optical film.

<Preparation of optical film with adhesive layer>
The pressure-sensitive adhesive layer was bonded to the polarizing plate (optical film) to produce an optical film with a pressure-sensitive adhesive layer (pressure-sensitive optical film).

[Examples 2 to 10 and Comparative Examples 1 and 2]
In Example 1, in the formation of the pressure-sensitive adhesive layer, an optical film with a pressure-sensitive adhesive layer was obtained in the same manner as in Example 1 except that the copolymers 2 to 12 were used instead of the copolymer 1 obtained in Synthesis Example 1. Was made.

  About the optical film with an adhesive layer obtained above, evaluation was implemented by the said method.

  From the evaluation results of Table 2, in all examples, by adjusting the refractive index difference within a desired range, it is possible to suppress the decrease in the degree of polarization, maintain high contrast, and have excellent adhesive properties and durability. I was able to confirm that On the other hand, in Comparative Examples 1 and 2, since the difference in refractive index within a desired range is deviated, the contrast is also lowered due to a significant decrease in the degree of polarization.

Claims (11)

A polymer composed of two or more monomers,
The monomer forms two or more different blocks in the polymer;
The block is formed from a homopolymer and / or a copolymer composed of two or more monomers;
Refractive index difference between the block state, and are 0.015 or less,
Among the blocks, the glass transition temperature of at least one block is 90 ° C. or higher, and the glass transition temperature of the other blocks is 0 ° C. or lower,
It said polymer (meth) optical pressure-sensitive adhesive agent characterized acrylate polymer der Rukoto. Of the two or more different blocks, at least one block is a block composed of two or more monomers,
Each of the two or more monomers has a refractive index when the two or more monomers each form a homopolymer,
It has at least one monomer each having a higher refractive index and a monomer having a lower refractive index than the refractive index of a block other than the block composed of the two or more monomers. Item 2. The optical pressure-sensitive adhesive according to Item 1. The optical pressure-sensitive adhesive according to claim 1 or 2 , wherein the polymer is at least one copolymer selected from the group consisting of a linear type, a star type, and a comb type. The optical pressure-sensitive adhesive according to any one of claims 1 to 3 , wherein the polymer has a weight average molecular weight of 10,000 to 300,000. The optical pressure-sensitive adhesive according to any one of claims 1 to 4 , comprising an isocyanate compound. A silane coupling agent is contained, The optical adhesive in any one of Claims 1-5 characterized by the above-mentioned. The optical adhesive layer formed from the optical adhesive in any one of Claims 1-6 . An optical film having the optical pressure-sensitive adhesive layer according to claim 7 . The optical film according to claim 8 , wherein the pressure-sensitive adhesive layer is formed on a substrate via an undercoat layer. An image display device using the optical film according to claim 8 . An image display device having the optical film, a polarizer, and a cell,
The image display device according to claim 10 , wherein the pressure-sensitive adhesive layer of the optical film is disposed closer to the cell side than the polarizer.