JP4870117B2 - Adhesive optical film and image display device - Google Patents

Description

  The present invention relates to an adhesive optical film. The present invention also 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 adhesive optical film.

  The pressure-sensitive adhesive optical film of the present invention has a discotic liquid crystal layer and is useful as an optical compensation film for improving display contrast and viewing angle characteristics of display colors. It is useful as an elliptically polarizing plate with an optical compensation function.

  Liquid crystal display devices are rapidly marketed in watches, mobile phones, PDAs, notebook computers, personal computer monitors, DVD players, TVs, and the like. A liquid crystal display device visualizes a change in polarization state due to switching of liquid crystal, and a polarizer is used from the display principle. In particular, displays with higher brightness and higher contrast are required for applications such as TV, and light polarizers with higher brightness (high transmittance) and higher contrast (high polarization degree) have been developed and introduced. Yes.

  At present, the mainstream method of a general liquid crystal display device is a TFT-LCD using a TN liquid crystal. This method has advantages such as high response speed and high contrast. However, when the display of a panel using TN liquid crystal is viewed from an angle inclined from the normal direction, the contrast is remarkably lowered, and gradation inversion that reverses the gradation display occurs. It has the characteristic that the viewing angle is narrow. On the other hand, in applications such as large PC monitors and televisions, high contrast, wide viewing angle, and small display color change due to viewing angle are required. Therefore, when a TN mode TFT-LCD is used for such applications, a retardation film for compensating the viewing angle is indispensable.

  As this retardation film, a stretched birefringent polymer film has been conventionally used. Recently, it has been proposed to use an optical compensation film having an optically anisotropic layer formed of liquid crystalline molecules on a transparent support, instead of an optical compensation film made of a stretched birefringent film. Since liquid crystal molecules have various alignment forms, it has become possible to realize optical properties that cannot be obtained with conventional stretched birefringent polymer films by using liquid crystal molecules.

  As a viewing angle compensation retardation film as described above, for example, a wide view film manufactured by Fuji Photo Film Co., Ltd. using a discotic liquid crystal having negative refractive index anisotropy has been proposed (Patent Document 1, Patent Document 2). This retardation film has a discotic liquid crystal layer having an optical axis inclined and oriented on one side of a transparent substrate film. This retardation film is mainly intended to improve viewing angle characteristics in a voltage application state for black display. That is, in a voltage application state, the liquid crystal molecules in the liquid crystal cell exhibit positive refractive index anisotropy having an optical axis inclined from the glass substrate. In order to compensate for the retardation due to the refractive index anisotropy, the retardation film uses a liquid crystalline molecule having an optical axis inclined from the normal direction of the film and having negative refractive index anisotropy.

  In the retardation film for compensating the viewing angle, a polarizer is laminated on the transparent substrate film and used as an elliptically polarizing plate, while an adhesive layer is laminated on the discotic liquid crystal layer. An adhesive optical film such as a retardation film or an elliptically polarizing plate on which the pressure-sensitive adhesive layer is laminated is used by being bonded to a liquid crystal cell or the like via the pressure-sensitive adhesive layer.

  As the pressure-sensitive adhesive used in the optical film with the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is frequently used because of its excellent adhesion and transparency. Further, the acrylic pressure-sensitive adhesive is often crosslinked using an isocyanate-based crosslinking agent, and mainly utilizes a bond with a functional monomer copolymerized with an acrylic polymer.

  A liquid crystal panel in which the optical film is bonded to a liquid crystal cell is mounted and used in a liquid crystal display device. Liquid crystal display devices are used not only in calculators but also in watches, televisions, monitors, and the like. Since liquid crystal display devices are subjected to various conditions such as heating and humidification conditions, high durability that does not impair display quality is required even in such an environment.

  However, when the liquid crystal display device is subjected to heating or humidification conditions, there is a problem that display unevenness occurs in the peripheral portion of the liquid crystal panel and display uniformity is lowered. This display uniformity may be particularly noticeable when the above-described viewing angle compensation retardation film or elliptically polarizing plate is used. The cause of this display uniformity is considered to be due to birefringence generated in the optical film due to heat shrinkage of the polarizer, heat oxidation deterioration of the discotic liquid crystal layer, and the like.

  In order to improve the display uniformity, a pressure-sensitive adhesive composition containing a plasticizer and an oligomer component is used as a pressure-sensitive adhesive for an optical film with a pressure-sensitive adhesive, and stress relaxation is imparted to the pressure-sensitive adhesive layer. (Patent Document 3, Patent Document 4). However, these pressure-sensitive adhesive compositions have a problem of poor appearance due to the deposition of additives such as plasticizers and oligomer components in a long-time heating test, and have poor reworkability. It is easy to deform, so when cutting an optical film with an adhesive, the adhesive is taken away by the cutting blade, or the adhesive sticks out of the cut surface, and the handling property is poor, and under heating or humidification conditions, etc. In such a case, problems such as peeling and foaming occur, resulting in insufficient durability.

  Moreover, it is a value obtained by containing an aromatic ring-containing monomer as a copolymerization component, having a weight average molecular weight (Mw) of 800,000 to 1.6 million, and dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn). Adhesive containing an acrylic polymer with a dispersity (Mw / Mn) of 10 to 50 reduces birefringence and relieves stress due to dimensional change, peels off under high humidity conditions, and leaks light It has been proposed to suppress color unevenness due to (Patent Literature 5, Patent Literature 6). In addition, the pressure-sensitive adhesive containing an acrylic polymer having an aromatic ring as a copolymerization component and containing an acrylic polymer having a weight average molecular weight (Mw) of 1,000,000 to 2,000,000 reduces stress due to dimensional change. It has been proposed to improve display uniformity by bringing the refractive index of the pressure-sensitive adhesive layer close to 0 (Patent Document 7). However, as in Patent Documents 5 to 7, the pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive containing an acrylic polymer containing an aromatic ring-containing monomer as a copolymerization component has insufficient durability under humidified conditions. , Peeling easily occurs on the pressure-sensitive adhesive layer. Moreover, the pressure-sensitive adhesive layer imparted with stress relaxation properties is inferior in handling properties because the pressure-sensitive adhesive layer is easily deformed. In addition, the pressure-sensitive adhesive layer has a problem that when the heating and humidifying conditions become severe or the size of a liquid crystal display device or the like becomes large, the contraction stress of the polarizer cannot be relaxed and display unevenness occurs.

  In addition to the above, a pressure-sensitive adhesive containing an acrylic polymer containing an alicyclic monomer or an aromatic-containing monomer as a copolymerization component has been proposed as a low-polarity film pressure-sensitive adhesive (Patent Document 8). Further, it has been proposed to form a pressure-sensitive adhesive layer from a pressure-sensitive adhesive containing an acrylic polymer containing a monomer having a benzene ring in the molecule as a copolymerization component (Patent Document 9). However, these pressure-sensitive adhesives contain an acrylic polymer containing an aromatic ring-containing monomer as a copolymerization component, so the durability under humid conditions is insufficient, and peeling occurs in the pressure-sensitive adhesive layer. It's easy to do.

JP-A-8-95032 Japanese Patent No. 2767382 Japanese Patent Laid-Open No. 9-87593 JP-A-10-279907 JP 2007-138056 A JP 2007-138057 A JP 2007-169329 A JP 2005-53976 A JP-A-57-221634

  The present invention is an adhesive optical film having a discotic liquid crystal layer in which a discotic liquid crystal compound is aligned on one side of a transparent substrate film, and further having an adhesive layer laminated on the discotic liquid crystal layer. Thus, it is an object of the present invention to provide a pressure-sensitive adhesive optical film having good durability and display uniformity and good handling properties.

  Another object of the present invention is to provide an image display device using the adhesive 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 pressure-sensitive adhesive optical film, and have completed the present invention.

That is, the present invention is an adhesive optical film in which an adhesive layer is provided via an undercoat layer on the discotic liquid crystal layer of an optical film having a discotic liquid crystal layer on one side of a transparent substrate film.
The undercoat layer contains polymers and an antioxidant,
The pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive containing an acrylic polymer, a crosslinking agent and a silane coupling agent,
Acrylic polymers are used as monomer units.
49.9 to 84.9% by weight of alkyl (meth) acrylate (a1),
15 to 50% by weight of (meth) acrylate (a2) having an aromatic ring structure, and 0.1 to 5% by weight of monomer (a3) excluding component (a1) and component (a2) ,And,
The acrylic polymer has a weight average molecular weight (Mw) of 1.4 to 2.5 million and a dispersity (Mw / Mn) of 3 to 10 which is a value obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn). It is related with the adhesive optical film characterized by being.

  In the pressure-sensitive adhesive optical film, the polymer of the undercoat layer is preferably a polymer having a primary amino group.

  In the pressure-sensitive adhesive optical film, the antioxidant is preferably at least one selected from phenol-based, phosphorus-based, sulfur-based and amine-based antioxidants.

  In the pressure-sensitive adhesive optical film, the undercoat layer preferably contains 0.01 to 1000 parts by weight of an antioxidant with respect to 100 parts by weight of the polymers.

  In the pressure-sensitive adhesive optical film, the silane coupling agent preferably has an alkoxysilyl group and an aromatic ring structure in the molecule. The silane coupling agent is preferably an amino group-containing silane coupling agent having an aromatic ring structure.

  In the pressure-sensitive adhesive optical film, the amount of the silane coupling agent is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the acrylic polymer.

  In the pressure-sensitive adhesive optical film, as the optical film, one in which a polarizer is laminated on one side of a transparent substrate film on the side where a discotic liquid crystal layer is not formed can be used.

  The present invention also relates to an image display device using the adhesive optical film.

  The pressure-sensitive adhesive optical film of the present invention has a discotic liquid crystal layer that functions as an optical compensation layer. As a base polymer of a pressure-sensitive adhesive that forms a pressure-sensitive adhesive layer provided on the discotic liquid crystal layer, an alkyl (meth) acrylate ( an acrylic polymer having a weight average molecular weight of 1,400,000 to 2,500,000 and a dispersity (Mw / Mn) of 3 to 10, containing a1) and a (meth) acrylate (a2) having an aromatic ring structure as a monomer component And a pressure-sensitive adhesive layer is provided on the discotic liquid crystal layer through an undercoat layer containing polymers and an antioxidant. The pressure-sensitive adhesive optical film of the present invention satisfies durability, display uniformity, and handling properties due to these specific pressure-sensitive adhesive layer and undercoat layer.

  In the pressure-sensitive adhesive optical film of the present invention, the specific pressure-sensitive adhesive layer and the undercoat layer suppress display unevenness in the peripheral portion of the display screen and satisfy display uniformity. In addition to the base polymer, Unlike the pressure-sensitive adhesive using the additive, the additive itself does not precipitate and the appearance and the pressure-sensitive adhesive do not deteriorate.

  The present invention will be described below with reference to the drawings. As shown in FIG. 1, the pressure-sensitive adhesive optical film of the present invention has a discotic liquid crystal layer 3 on one side of a transparent substrate film 1, and the discotic liquid crystal layer 3 has an undercoat layer 4 interposed therebetween. An adhesive layer 5 is provided. In FIG. 1, the case where the alignment film 2 is provided between the transparent substrate film 1 and the discotic liquid crystal layer 3 is illustrated, but instead of the alignment film 2, one side of the transparent substrate film 1 is rubbed. Can be used.

  FIG. 2 shows the adhesive optical film of FIG. 1 in which a polarizer 6 and then a transparent protective film 7 are laminated on one side of the transparent substrate film 1 on the side where the discotic liquid crystal layer 3 is not formed. This is the case. In FIG. 2, the transparent substrate film 1 also serves as a transparent protective film for the polarizer 6.

  Various transparent materials can be used as the 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) -Based polymer, polycarbonate-based polymer and the like. 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 are also examples of polymers that form 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 a thermoplastic resin having unsubstituted phenyl and a nitrile group. A specific example is 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.

  Although the thickness of a transparent base film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin film property. In particular, 5 to 200 μm is preferable.

  Moreover, it is preferable that a transparent base film has as little coloring 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.

  The discotic liquid crystal layer is usually formed by alignment and curing of a discotic liquid crystal compound having a polymerizable unsaturated group. The discotic liquid crystal layer is useful as an optical compensation layer, and can improve the viewing angle, contrast, brightness, and the like. The discotic liquid crystal layer is preferably one in which a discotic liquid crystal compound is tilted. The thickness of the discotic liquid crystal layer is usually about 0.5 to 10 μm.

  The discotic liquid crystal compound has a negative refractive index anisotropy (uniaxiality). Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives and B.I. Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), such as azacrown and phenylacetylene macrocycles, etc., which are generally used as a mother nucleus at the center of a molecule, and are a linear alkyl group or alkoxy group, substituted A structure in which a benzoyloxy group or the like is radially substituted as a straight chain thereof exhibits liquid crystallinity and includes what is generally called a discotic liquid crystal. However, the molecule itself is not limited to the above description as long as the molecule itself has negative uniaxiality and can give a certain orientation. In the present invention, as the discotic liquid crystal compound, those having a polymerizable unsaturated group (for example, acryloyl group, methacryloyl group, vinyl group, allyl group, etc.) that undergo a curing reaction with heat, light, etc. are usually used. It is done. Note that the discotic liquid crystal layer does not necessarily need to be a final product, and includes a liquid crystal layer that has been polymerized or cross-linked by the reaction of a polymerizable unsaturated group to increase the molecular weight and lose liquid crystallinity.

  In addition, discotic liquid crystal compounds are optical molecules such as reaction products of discotic liquid crystals that no longer exhibit liquid crystallinity due to reactions with various discotic liquid crystal compounds and other low molecular compounds and polymers. In general, it means all compounds having negative uniaxiality.

  For the alignment treatment of the discotic liquid crystal, the surface of the transparent substrate film is rubbed or an alignment film is used. Examples of the alignment film include an inorganic oblique deposition film or an alignment film obtained by rubbing a specific organic polymer film. There is a thin film in which isomerization is caused by light, such as an LB film made of an azobenzene derivative, and molecules are uniformly arranged with directionality. Examples of the organic alignment film include polyimide films, and organic polymer films that form a hydrophobic surface such as alkyl chain-modified poval, polyvinyl butyral, and polymethyl methacrylate. In addition, a SiO oblique vapor deposition film is an example of the inorganic oblique vapor deposition film.

  As a means for tilting and aligning the discotic liquid crystal compound, for example, an alignment film is formed on a transparent substrate film, and then a discotic liquid crystal compound (polymerizable liquid crystal compound) is applied to be in a tilt alignment state. A method of fixing by irradiation with light such as ultraviolet light or heat can be used. It is also possible to form the discotic liquid crystal on another alignment substrate by tilting and then transferring it onto a transparent support using an optically transparent adhesive or pressure sensitive adhesive. is there.

  As such a discotic liquid crystal layer, those described in Patent Documents 1 and 2 are preferably used. A wide-view film manufactured by Fuji Photo Film Co., Ltd. is one in which such a discotic liquid crystal inclined alignment layer is formed on a cellulosic polymer film.

  The undercoat layer is formed of an undercoat containing a polymer and an antioxidant. It is desirable that the polymer material is a material that exhibits good adhesion to both the pressure-sensitive adhesive layer and the discotic liquid crystal layer and forms a film having excellent cohesive strength.

  Examples of the polymers include polyurethane resins, polyester resins, and polymers containing amino groups 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.

  For example, when the pressure-sensitive adhesive layer contains an isocyanate compound, the polymer preferably has a functional group having reactivity with the isocyanate compound. As the polymers, polymers containing an amino group in the molecule are preferable. In particular, those having a primary amino group at the terminal are preferably used, and are firmly adhered by reaction with an isocyanate compound. The polymer having a primary amino group at the terminal is preferably a poly (meth) acrylic acid ester having a primary amino group at the terminal.

  Examples of polymers containing an amino group in the molecule include polymers of amino group-containing monomers such as polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, and dimethylaminoethyl acrylate. Can do. Among these, polyethyleneimine type is preferable. As the polyethyleneimine-based material, any material having a polyethyleneimine structure may be used, and examples thereof include polyethyleneimine, an ethyleneimine adduct and / or a polyethyleneimine adduct to polyacrylic acid ester. In particular, an ethyleneimine adduct and / or a polyethyleneimine adduct to a polyacrylic acid ester, which is a poly (meth) acrylic acid ester having a primary amino group at the terminal, is preferable.

  Polyethyleneimine is not particularly limited, and various types can be used. The weight average molecular weight of polyethyleneimine is not particularly limited, but is usually about 1 to 1,000,000. Examples of commercially available polyethyleneimine products include Epomin SP series (SP-003, SP006, SP012, SP018, SP103, SP110, SP200, etc.) manufactured by Nippon Shokubai Co., Ltd., and Epomin P-1000. Of these, Epomin P-1000 is preferred.

  The polyacrylic acid ester of an ethyleneimine adduct and / or a polyethyleneimine adduct to a polyacrylic acid ester is an alkyl (meth) acrylate that constitutes a base polymer (acrylic polymer) of an acrylic pressure-sensitive adhesive described later and a copolymer thereof. It can be obtained by emulsion polymerization of monomers according to a conventional method. As the copolymerization monomer, a monomer having a functional group such as a carboxyl group for reacting ethyleneimine or the like is used. The proportion of the monomer having a functional group such as a carboxyl group is appropriately adjusted depending on the proportion of ethyleneimine to be reacted. Further, as the copolymerization monomer, it is preferable to use a styrene monomer. Moreover, it can also be set as the addition product which grafted polyethyleneimine by making the polyethyleneimine separately synthesize | combined react with the carboxyl group etc. in acrylic ester. For example, as an example of a commercially available product, POLYMENT NK-380 manufactured by Nippon Shokubai Co., Ltd. can be mentioned.

  Further, an ethyleneimine adduct and / or a polyethyleneimine adduct of an acrylic polymer emulsion can be used. For example, as an example of a commercially available product, POLYMENT SK-1000 manufactured by Nippon Shokubai Co., Ltd. can be mentioned.

  In addition to the above, as a polymer having a primary amino group at the terminal, a carboxyl group or a hydroxyl group in the polyacrylate ester is reacted with an excess diisocyanate, and further reacted with an excess diamine to form a primary amino group at the terminal. What has been introduced. The poly (meth) acrylic acid ester having a primary amino group at the terminal can be obtained by copolymerizing the (meth) acrylic acid ester and a monomer having a primary amino group at the terminal. Examples of the monomer having a primary amino group at the terminal include aminoethyl (meth) acrylate and aminopropyl (meth) acrylate.

  Examples of the antioxidant contained in the undercoat layer include phenol-based, phosphorus-based, sulfur-based and amine-based antioxidants, and at least one selected from these is used. Among these, a phenolic antioxidant is preferable.

  Specific examples of phenolic antioxidants include 2,6-di-t-butyl-p-cresol, 2,6-di-t-butyl-4-ethylphenol, 2,6- Dicyclohexyl-4-methylphenol, 2,6-diisopropyl-4-ethylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol, 2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-4-ethyl-6-t-octylphenol, 2-isobutyl-4-ethyl- 6-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, styrenated mixed cresol, DL- -Tocopherol, stearyl β- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and the like as a bicyclic phenol compound, 2,2′-methylenebis (4-methyl-6-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), 4,4'-thiobis (3-methyl-6-t-butylphenol), 2,2'-thiobis (4-methyl-6-t) -Butylphenol), 4,4'-methylenebis (2,6-di-t-butylphenol), 2,2'-methylenebis [6- (1-methylcyclohexyl) -p-cresol], 2,2'-ethylidenebis (4,6-di-t-butylphenol), 2,2'-butylidenebis (2-t-butyl-4-methylphenol), 3,6-dioxaoctamethy Renbis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate], triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1 , 6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2′-thiodiethylenebis [3- (3,5-di-t-butyl- 4-hydroxyphenyl) propionate], etc. as 1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-tris (2 , 6-Dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 1,3,5-tris [(3,5-di-tert-butyl-4-hydroxyl Nyl) propionyloxyethyl] isocyanurate, tris (4-t-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate, 1,3,5-trimethyl-2,4,6-tris (3,5 -Di-t-butyl-4-hydroxybenzyl) benzene or the like as a tetracyclic phenol compound, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane or the like, Examples of phosphorus-containing phenol compounds include bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium and bis (3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) nickel. Can be mentioned.

  Specific examples of phosphorus antioxidants include trioctyl phosphite, trilauryl phosphite, tristridecyl phosphite, trisisodecyl phosphite, phenyl diisooctyl phosphite, phenyl diisodecyl phosphite, phenyl di (tridecyl) phos Phyto, diphenylisooctyl phosphite, diphenylisodecyl phosphite, diphenyl tridecyl phosphite, triphenyl phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, tris (Butoxyethyl) phosphite, tetratridecyl-4,4'-butylidenebis (3-methyl-6-tert-butylphenol) -diphosphite, 4,4'-isopropylidene-diphenol alkylphosphine (Wherein alkyl has about 12 to 15 carbon atoms), 4,4'-isopropylidenebis (2-t-butylphenol) .di (nonylphenyl) phosphite, tris (biphenyl) phosphite, tetra (tridecyl)- 1,1,3-tris (2-methyl-5-tert-butyl-4-hydroxyphenyl) butanediphosphite, tris (3,5-di-tert-butyl-4-hydroxyphenyl) phosphite, hydrogenation -4,4'-isopropylidenediphenol polyphosphite, bis (octylphenyl) -bis [4,4'-butylidenebis (3-methyl-6-tert-butylphenol)], 1,6-hexanediol diphosphite Hexatridecyl-1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenol) diphosphine Iit, tris [4,4'-isopropylidenebis (2-t-butylphenol)] phosphite, tris (1,3-distearoyloxyisopropyl) phosphite, 9,10-dihydro-9-phosphaphenanthrene -10-oxide, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylenediphosphonite, distearyl pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, phenyl 4,4'-isopropylidenediphenol pentaerythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methyl) Phenyl) pentaerythritol diphosphite and phenylbisph Such as Nord -A- pentaerythritol diphosphite, and the like.

  As the sulfur-based antioxidant, dialkylthiodipropionate and polyhydric alcohol esters of alkylthiopropionic acid are preferably used. The dialkylthiodipropionate used here is preferably a dialkylthiodipropionate having an alkyl group having 6 to 20 carbon atoms, and the polyhydric alcohol ester of alkylthiopropionic acid is an alkyl having 4 to 20 carbon atoms. Polyalkyl alcohol esters of alkylthiopropionic acid having a group are preferred. In this case, examples of the polyhydric alcohol constituting the polyhydric alcohol ester include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and trishydroxyethyl isocyanurate. Examples of such dialkylthiodipropionate include dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate. On the other hand, as the polyhydric alcohol ester of alkylthiopropionic acid, for example, glycerin tributylthiopropionate, glycerin trioctylthiopropionate, glycerin trilauryl thiopropionate, glycerin tristearyl thiopropionate, trimethylol ethane tributyl Thiopropionate, trimethylol ethane trioctyl thiopropionate, trimethylol ethane trilauryl thiopropionate, trimethylol ethane tristearyl thiopropionate, pentaerythritol tetrabutyl thiopropionate, pentaerythritol tetraoctyl thiopro Pionate, pentaerythritol tetralauryl thiopropionate, pentaerythritol tetrastearyl thiopropionate, etc. It can be mentioned.

  Specific examples of amine-based antioxidants include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, dimethyl succinate and 1- (2-hydroxyethyl) -4-hydroxy-2,2 , 6,6-tetramethylpiperidineethanol polycondensate, N, N ′, N ″, N ″ ″-tetrakis- (4,6-bis- (butyl- (N-methyl-2,2,6 , 6-Tetramethylpiperidin-4-yl) amino) -triazin-2-yl) -4,7-diazadecane-1,10-diamine, dibutylamine 1,3,5-triazine N, N′-bis (2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N- (2,2,6,6-tetramethyl-4-piperidyl) butylamine polycondensate, poly [ {6- (1,1,3,3-Te Lamethylbutyl) amino-1,3,5-triazine-2,4-diyl} {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene {(2,2,6,6-tetra Methyl-4-piperidyl) imino}], tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 2,2,6,6-tetra Methyl-4-piperidylbenzoate, bis- (1,2,6,6-pentamethyl-4-pepyridyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalo Nate, bis- (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 1,1 '-(1,2-ethanediyl) bis (3,3,5,5-tetramethyl Piperazinone), (Mi Xust 2,2,6,6-tetramethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, (mixed 1,2,2,6,6-pentamethyl-4-piperidyl / Tridecyl) -1,2,3,4-butanetetracarboxylate, mixed [2,2,6,6-tetramethyl-4-piperidyl / β, β, β ′, β′-tetramethyl-3, 9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl] -1,2,3,4-butanetetracarboxylate, mixed [1,2,2,6,6- Pentamethyl-4-piperidyl / β, β, β ′, β′-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] diethyl] -1,2,3 , 4-Butanetetracarboxylate N, N'-bis (3-aminopropyl) ethylenediamine-2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro- 1,3,5-triazine condensate, poly [6-N-morpholyl-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino ] Hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imide], N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine and 1 , 2-dibromoethane condensate [N- (2,2,6,6-tetramethyl-4-piperidyl) -2-methyl-2- (2,2,6,6-tetramethyl-4- And piperidyl) imino] propionamide It can be.

  The undercoat layer contains polymers and an antioxidant, and usually contains 0.01 to 1000 parts by weight of an antioxidant with respect to 100 parts by weight of the polymers. The proportion of the antioxidant used is preferably 0.1 to 500 parts by weight, more preferably 1 to 350 parts by weight, still more preferably 10 to 150 parts by weight, and still more preferably 50 to 130 parts by weight. If the proportion of the antioxidant used is less than 0.01 parts by weight, the display uniformity may not be satisfied. On the other hand, when it exceeds 1000 weight part, it is unpreferable at the point of anchoring property or an external appearance.

  In forming the undercoat layer, in addition to the polymer containing an amino group, a compound that reacts with the polymer containing an amino group can be mixed and crosslinked to improve the strength of the undercoat layer. Examples of the compound that reacts with the polymer containing an amino group include an epoxy compound.

  The undercoat layer is formed on the discotic liquid crystal layer of the optical film. 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. . 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. The coating amount (solid content) of the undercoat layer is preferably 0.1 to 5 cubic centimeters per square meter. Furthermore, it is preferably 0.1 to 1 cubic centimeter, more preferably 0.1 to 0.5 cubic centimeter.

The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the present invention comprises, as a base polymer, an alkyl (meth) acrylate (a1), a (meth) acrylate (a2) having an aromatic ring structure, and a component (a1) and a component (a2). An acrylic polymer containing the monomer (a3) as a monomer unit is excluded. (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

  The alkyl group of the alkyl (meth) acrylate (a1) has about 1-18 carbon atoms, preferably 1-9 carbon atoms, and the alkyl group may be linear or branched. Specific examples of the alkyl (meth) acrylate include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate. , Pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, lauryl ( And (meth) acrylate, stearyl (meth) acrylate, and the like. These can be used alone or in combination. The average carbon number of these alkyl groups is preferably 4-12.

  Examples of the aromatic ring structure of the (meth) acrylate (a2) having an aromatic ring structure include a benzene ring, a naphthalene ring, a thiophene ring, a pyridine ring, a pyrrole ring, and a furan ring. Examples of the (meth) acrylate having an aromatic ring structure include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenoxy-2-hydroxypropyl (meth) acrylate, phenol ethylene oxide modified (meth) acrylate, and 2-naphthoxyethyl. (Meth) acrylate, 2- (4-methoxy-1-naphthoxy) ethyl (meth) acrylate, phenoxypropyl (meth) acrylate, phenoxyethylene glycol (meth) acrylate, thiophenyl (meth) acrylate, pyridyl (meth) acrylate, pyrrolyl Examples include (meth) acrylate, phenyl (meth) acrylate, and polystyryl (meth) acrylate. Although this reason is not certain, it is thought that one of the reasons is that the polarizability of the aromatic ring is high. In particular, (meth) acrylates having a phenyl group such as phenoxyethyl (meth) acrylate and phenoxy-2-hydroxypropyl (meth) acrylate have a higher field rate because the benzene ring and the ether bond are connected. Therefore, it is preferable.

  The component (a3) is used for modifying the base polymer. 1 type (s) or 2 or more types can be used for the said (a3) component. Examples of the component (a3) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl. Hydroxyl group-containing monomers such as (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate; (meth) acrylic acid, carboxyethyl (meta ) Carboxyl group-containing monomers such as acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; monomers containing acid anhydride groups such as maleic anhydride and itaconic anhydride; Caprolactone adduct of phosphoric acid; sulfonic acid group-containing monomer such as allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate; 2-hydroxy And phosphoric acid group-containing monomers such as ethylacryloyl phosphate.

  Moreover, a nitrogen-containing vinyl monomer is mention | raise | lifted as said (a3) component. For example, maleimide; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methyl (meth) acrylamide, N-butyl (meth) ) (N-substituted) amide monomers such as acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate, aminopropyl (meth) Alkylaminoalkyl (meth) acrylate monomers such as acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate; methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate Alkoxyalkyl (meth) acrylate monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide Examples of monomers for modification are succinimide-based monomers.

  Further, as the component (a3), vinyl monomers such as vinyl acetate, vinyl propionate, N-vinylcarboxylic amides, styrene, α-methylstyrene, N-vinylcaprolactam; nitriles such as acrylonitrile and methacrylonitrile Monomers: Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; glycols such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate Acrylic ester monomers; (meth) acrylate monomers such as fluorine (meth) acrylate, silicone (meth) acrylate, and 2-methoxyethyl acrylate It can be used Domo.

  In the acrylic polymer, the ratio of the alkyl (meth) acrylate (a1), the (meth) acrylate (a2) having an aromatic ring structure, and the monomer (a3) is 49. alkyl (meth) acrylate (a1) as a monomer unit. 9 to 84.9% by weight, 15 to 50% by weight of (meth) acrylate (a2) having an aromatic ring structure, and 0.1 to 5% by weight of monomer (a3) are used.

  The (meth) acrylate (a2) having an aromatic ring structure is preferably 20 to 40% by weight, and more preferably 25 to 35% by weight. The proportion of the component (a2) is preferably 15% by weight or more from the viewpoint of display uniformity, and by being 50% by weight or less, display uniformity and durability can be improved.

  The proportion of the component (a3) is preferably 0.5 to 4.5% by weight, and more preferably 1 to 4% by weight. When the proportion of the component (a3) exceeds 5% by weight, it is not preferable in that the flexibility as an adhesive may be impaired. On the other hand, when the proportion of the component (a3) is less than 0.1% by weight, the polarity of the base polymer is lowered, and the durability is lowered.

  As the component (a3), a hydroxyl group-containing monomer is preferably used because it can be a crosslinking point, particularly a crosslinking point with an isocyanate crosslinking agent. When the hydroxyl group-containing monomer is used, the proportion is about 0.1 to 5% by weight, preferably 0.5 to 4% by weight, and more preferably 1 to 3.5% by weight. Further, from the viewpoint of good adhesiveness, a monomer containing a carboxyl group, particularly acrylic acid, is preferably used. When using the monomer containing a carboxyl group, the ratio is about 0.1 to 5 weight%, Preferably it is 0.2 to 3 weight%, More preferably, it is 0.3 to 2 weight%. In addition, the alkyl (meth) acrylate (a1) becomes the remainder of the component (a2) and the component (a3).

  The acrylic polymer can be produced by various known methods. For example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method, or a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known azo and peroxide initiators can be used. The reaction temperature is usually about 50 to 80 ° C., and the reaction time is 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and ethyl acetate, toluene and the like are generally used as the solvent for the acrylic polymer. The solution concentration is usually about 20 to 80% by weight. The acrylic polymer can be obtained as an aqueous emulsion.

  The weight average molecular weight (Mw) of the acrylic polymer is from 1.4 million to 2.5 million, preferably from 1.5 million to 2.4 million, and more preferably from 1.6 million to 2.3 million. When the weight average molecular weight is less than 1.4 million, display uniformity, durability, and handling properties cannot be satisfied. On the other hand, when the weight average molecular weight exceeds 2.5 million, it is not preferable in that the adhesiveness is lowered. The acrylic polymer has a value (Mw / Mn) obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn), that is, the dispersity is 3 to 10. The degree of dispersion is preferably 3.5 to 8, and more preferably 4 to 7. Controlling the degree of dispersion within the above range is preferable for satisfying display uniformity. The degree of dispersion can be controlled within the above range by controlling the concentration at the time of polymerizing the acrylic polymer, the disclosed agent type, the amount thereof, and the polymerization temperature. The monomer concentration should be high and the polymerization temperature should be low. Specifically, when azobisisobutyronitrile or benzoyl peroxide is used as a disclosure agent, this can be achieved by reacting at a polymerization temperature of about 50 to 60 ° C. for about 8 hours. When the polymerization temperature is too low, the polymerization reaction does not start. When the polymerization temperature is too high, the degree of dispersion increases and the display uniformity deteriorates. Further, even if the initiator is re-introduced during the polymerization, the degree of dispersion increases and the display uniformity deteriorates.

The weight average molecular weight (Mw) and dispersity (Mw / Mn) of the acrylic polymer were measured under the following conditions of the GPC (gel permeation chromatography) method.
Analyzer: HLC-8120GPC manufactured by Tosoh Corporation.
Column: manufactured by Tosoh Corporation, G7000HXL + GMHXL + GMHXL.
Column size: 7.8 mmφ × 30 cm each 90 cm in total.
Column temperature: 40 ° C.
Flow rate: 0.8 ml / min.
Injection volume: 100 μl.
Eluent: tetrahydrofuran.
Detector: Suggested refractometer.
Standard sample: polystyrene.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the present invention contains a crosslinking agent in addition to the acrylic polymer as the base polymer. The cross-linking agent can improve the adhesion and durability with the optical film, and can maintain the reliability at high temperature and the shape of the pressure-sensitive adhesive itself. As the cross-linking agent, isocyanate, epoxy, peroxide, metal chelate, oxazoline, and the like can be used as appropriate. These crosslinking agents can be used alone or in combination of two or more. As the cross-linking agent, a cross-linking agent containing a functional group reactive with a hydroxyl group is preferable, and an isocyanate-based cross-linking agent is particularly preferable.

  As the isocyanate-based crosslinking agent, an isocyanate compound is used. Isocyanate compounds include isocyanate monomers such as tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, and these isocyanates. Adduct isocyanate compounds in which monomers are added with trimethylolpropane, etc .; isocyanurates, burette type compounds, and urethane prepolymers obtained by addition reaction of known polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc. Examples thereof include polymer type isocyanate.

  Examples of the epoxy-based crosslinking agent include bisphenol A epichlorohydrin type epoxy resins. Examples of the epoxy crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, Diglycidylaniline, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′— Examples include tetraglycidylaminophenyl methane, triglycidyl isocyanurate, m-N, N-diglycidylaminophenyl glycidyl ether, N, N-diglycidyl toluidine, and N, N-diglycidyl aniline.

  Various peroxides are used as the peroxide-based crosslinking agent. Peroxides include di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate , T-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxyisobutyrate, 1,3,3-tetramethylbutylperoxy 2-ethylhexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, and the like. Of these, di (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, and dibenzoyl peroxide, which are particularly excellent in crosslinking reaction efficiency, are preferably used.

  The amount of the crosslinking agent used is 10 parts by weight or less, preferably 0.01 to 5 parts by weight, and more preferably 0.02 to 3 parts by weight with respect to 100 parts by weight of the acrylic polymer. When the proportion of the crosslinking agent used exceeds 10 parts by weight, it is not preferable in that crosslinking may proceed excessively and adhesiveness may be lowered.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the present invention contains a silane coupling agent. Silane coupling agents having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, etc. 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 agent such as pyrtriethoxysilane; 3-chloropropyltrimethoxysilane; acetoacetyl group-containing trimethoxysilane; p-styryltrimethoxysilane, p-styryltriethoxysilane, N-phenyl-γ- Silane coupling having an aromatic ring such as aminopropyltrimethoxysilane, N-phenyl-γ-aminoethyltrimethoxysilane, N-phenyl-γ-aminopropyltriethoxysilane, N-phenyl-γ-aminoethyltrimethoxysilane Agents and the like. A silane coupling agent may be used individually by 1 type, and may mix and use 2 or more types. A silane coupling agent is preferable for improving durability.

  Among the silane coupling agents, those having an alkoxysilyl group and an aromatic ring structure in the molecule are suitable. Examples of the aromatic ring structure include the same benzene ring, naphthalene ring, thiophene ring, pyridine ring, pyrrole ring, furan ring and the like. The acrylic polymer contains (meth) acrylate (a2) having an aromatic ring structure as a monomer unit, but the acrylic polymer having an aromatic ring structure tends to be easily peeled off in a humidification test. Since the acrylic polymer having an aromatic ring structure and the silane coupling agent having an aromatic ring structure are highly compatible, the silane coupling agent having an aromatic ring structure can be selected and used as a silane coupling agent. Can be further improved. In particular, among silane coupling agents having an aromatic ring structure, N-phenyl-γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminoethyltrimethoxysilane, N-phenyl-γ-aminopropyltriethoxysilane An amino group-containing silane coupling agent having an aromatic ring structure such as N-phenyl-γ-aminoethyltrimethoxysilane is preferred, and a silane coupling agent having a phenylamino group is particularly preferred.

  The compounding amount of the silane coupling agent is about 0.01 to 5 parts by weight, preferably 0.02 to 3 parts by weight, and more preferably 0.1 to 1 part by weight with respect to 100 parts by weight of the acrylic polymer. . By using the silane coupling agent in the above range, it can be more reliably improved cohesive strength and durability, but if less than 0.01 parts by weight, the durability may be inferior, On the other hand, if it exceeds 5 parts by weight, the adhesive force to an optical member such as a liquid crystal cell may increase excessively.

  Furthermore, the pressure-sensitive adhesive of the present invention includes a tackifier, a plasticizer, a glass fiber, a glass bead, a metal powder, a filler composed of other inorganic powders, a pigment, a colorant, a filler, if necessary. Antioxidants, ultraviolet absorbers, and the like, and various additives can be appropriately used without departing from the object of the present invention. Moreover, it is good also as an adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility.

  The pressure-sensitive adhesive layer is formed by laminating on the undercoat layer. The forming method is not particularly limited, and the adhesive solution is applied onto the undercoat layer by an appropriate development method such as a casting method or a coating method, and is transferred by a release sheet provided with the adhesive layer. And the like. 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. After applying the pressure-sensitive adhesive solution, a solvent or water is volatilized in a drying step to obtain a pressure-sensitive adhesive layer having a predetermined thickness.

  The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive strength, and is generally 1 to 500 μm, preferably 1 to 50 μm. Furthermore, 1-40 micrometers is preferable, Furthermore, 5-30 micrometers is preferable, and 10-25 micrometers is especially preferable. When the thickness is less than 1 μm, the durability is deteriorated, and when the thickness is increased, floating or peeling due to foaming or the like is likely to occur, resulting in poor appearance.

  In addition, the pressure-sensitive adhesive layer can be formed by applying a UV-curable pressure-sensitive adhesive syrup on a release sheet and irradiating with radiation such as an electron beam or UV to form the pressure-sensitive adhesive layer containing the acrylic polymer. . At this time, since the pressure-sensitive adhesive contains a cross-linking agent, the reliability at high temperature and the shape of the pressure-sensitive adhesive itself can be maintained.

  The pressure-sensitive adhesive layer can be cross-linked by the drying step or the UV irradiation step, and a cross-linking form in which cross-linking is accelerated by aging by heating or standing at room temperature after drying can be selected.

  As a constituent material of the release sheet, paper, polyethylene, polypropylene, polyethylene terephthalate and other synthetic resin films, rubber sheets, paper, cloth, non-woven fabric, nets, foam sheets and metal foils, and appropriate thin leaf bodies such as laminates thereof Etc. In order to improve the peelability from the pressure-sensitive adhesive layer, the surface of the release sheet may be subjected to a low-adhesive release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment as necessary.

  In addition, in each layer such as an optical film and an adhesive layer of the adhesive optical film of the present invention, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, a nickel complex compound, etc. What gave the ultraviolet absorptivity by systems, such as a system processed with a ultraviolet absorber, etc. may be used.

  An antistatic agent can also be used in the adhesive 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 of the antistatic effect when heated and humidified, 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.

  As shown in FIG. 2, the optical film of the present invention has a polarizer 6 and then a transparent protective film 7 laminated on one side of the transparent substrate film 1 on the side where the discotic liquid crystal layer 3 is not formed. Can be used.

  The polarizer 6 is bonded to the transparent substrate film 1 using an adhesive. In FIG. 2, the transparent base film 1 also serves as a transparent protective film for the polarizer 6, but the transparent base film 1 has a polarizing plate having a transparent protective film on one or both sides of the polarizer. It can also be laminated.

  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 5 to 80 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 in which the polarizing plate is laminated, as an optical film used for the pressure-sensitive adhesive optical film of the present invention, an optical layer used for forming an image display device such as a liquid crystal display device may be laminated. it can. 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 give. 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.

  The pressure-sensitive adhesive optical film of the present invention can be preferably used for forming various image display devices such as liquid crystal display devices. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally 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. There is no particular limitation except that an adhesive optical film is used. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an adhesive optical film is disposed 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.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
<Preparation of adhesive>
In a four-flask equipped with a condenser, stirring blade and thermometer, 69 parts by weight of butyl acrylate, 30 parts by weight of phenoxyethyl acrylate, 1 part by weight of 4-hydroxybutyl acrylate and 2,2′-azobisisobutyronitrile After adding 0.1 part by weight with 140 parts by weight of ethyl acetate and sufficiently purging with nitrogen, the mixture was reacted at 55 ° C. for 8 hours with stirring under a nitrogen stream, and the weight average molecular weight was 1.7 million (Mw / Mn = 6.2) ) Of the acrylic polymer. A polyisocyanate-based cross-linking agent (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) made of a tolylene diisocyanate adduct of trimethylolpropane is 0.3 parts by weight based on 100 parts by weight of the solid content of the acrylic polymer solution. As a silane coupling agent, 0.2 part by weight of N-phenyl-γ-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., KBM573) was added to prepare an adhesive solution.

<Formation of adhesive layer>
The obtained pressure-sensitive adhesive solution was subjected to a reverse roll coating method so that the thickness of the pressure-sensitive adhesive layer after drying was 20 μm on a release sheet made of a polyester film (thickness: 38 μm) subjected to release treatment. It was applied and heat-treated at 130 ° C. for 3 minutes to volatilize the solvent and obtain an adhesive layer.

<Optical film>
A wide view (WV) film manufactured by Fuji Photo Film Co., Ltd. was used. The WV film had a discotic liquid crystal layer in which discotic liquid crystal molecules were tilted and aligned on a cellulose polymer film that was a transparent substrate film.

  The WV film was separated into an inclined alignment layer of discotic liquid crystal molecules, and the characteristics at λ = 590 nm were measured with KOBRA-21ADH manufactured by Oji Scientific Instruments. The in-plane maximum refractive index was nx, the refractive index in the direction perpendicular to the direction having the in-plane maximum refractive index was ny, and the refractive index in the thickness direction was nz. The thickness was d. The transparent support had Δnd = (nx−ny) × d = 12 nm and Rth = (nx−nz) × d = 100 nm. On the other hand, the tilted alignment layer measured the phase difference by changing the incident angle from −50 ° to 50 ° in the direction in which the optical axis is tilted. As a result, Δnd = 30 nm, Rth = 150 nm, average tilt angle θ = 17 °. Met.

  After the saponification treatment of the transparent substrate film side of the WV film, the saponification treatment surface and a polyvinyl alcohol polarizer (manufactured by Nitto Denko Corporation, SEG-5424WL) are pasted with a polyvinyl alcohol adhesive. Combined. On the other hand, a transparent protective film (triacetyl cellulose film, thickness 80 μm) is bonded to the other surface of the polarizer with the same polyvinyl alcohol-based adhesive as described above, and an optical film having a polarizing plate (with a viewing angle expansion film) Polarizing plate) was prepared.

<Preparation of primer>
A phenolic antioxidant (manufactured by Ciba Specialty Chemicals Co., Ltd.) was added to a solution obtained by diluting an acrylic acid ester having a primary amino group at the end (manufactured by Nippon Shokubai Co., Ltd., Poliment NK380) in toluene to a solid content of 2% by weight. , Irganox 1010) was added to 100 parts by weight of the solid content of the solution to prepare a primer.

<Preparation of adhesive optical film>
Apply the above primer to the surface of the discotic liquid crystal layer of the polarizing plate with the viewing angle widening film using a bar coater, and dry it to apply an undercoat layer (thickness of 80 nm) of 0.2 cubic centimeters. Formed. Subsequently, the release sheet in which the said adhesive layer was formed was bonded to the undercoat layer, and the adhesive optical film was produced.

Examples 2-8, Comparative Examples 1-10
In Example 1, the type or blending amount of the monomer component used for preparing the pressure-sensitive adhesive was changed as shown in Table 1, and the weight average molecular weight (Mw) and dispersity (Mw / Mn) of the resulting acrylic polymer. A pressure-sensitive adhesive solution was prepared in the same manner as in Example 1 except that the reaction conditions were controlled so as to be in Table 1. Except for Comparative Example 3, the degree of dispersion of the acrylic polymer was controlled so that the degree of dispersion was as shown in Table 1 by polymerization at a polymerization temperature of 50 to 60 ° C. for 8 hours. In Comparative Example 3, polymerization was performed at 60 ° C. for 4 hours, and then polymerization was performed at 80 ° C. for 2 hours, thereby controlling the dispersity to be as shown in Table 1. Moreover, the adhesive type optical film was produced like Example 1 except having used the said adhesive solution. However, in Comparative Examples 1, 2, 9, and 10, no undercoat layer was formed.

  The following evaluation was performed about the adhesive optical film obtained above. The results are shown in Table 1.

(Display uniformity)
The adhesive optical film was cut into a size of 580 mm long × 320 mm wide and prepared as a sample excluding the release sheet. This sample was bonded to a glass substrate for testing (a non-alkali glass plate having a thickness of 0.7 mm, manufactured by Corning, length 600 mm × width 350 mm) with a roller. After bonding, the sample was put into an autoclave (50 ° C., 5 atm × 15 minutes). Thereafter, the backlight was turned on in an atmosphere of 80 ° C., the sample was placed thereon, the sample was taken out after 500 hours, and the display uniformity of the sample was visually evaluated according to the following criteria.
A: No unevenness.
○: There is a slight unevenness, but there is no practical problem.
(Triangle | delta): The level which has a nonuniformity and a problem practically.
X: Unevenness can be clearly confirmed, and there is a problem in practical use.
XX: Unevenness is remarkable, and there is a large problem in practical use.

(durability)
An adhesive optical film (15-inch size) was attached to non-alkali glass (Corning 1737, thickness 0.7 mm) and treated in an autoclave at 50 ° C. and 0.5 MPa for 15 minutes. The sample was then subjected to 90 ° C. (heating) and 60 ° C., 95% R.D. H. Each is treated for 500 hours under the condition of (humidification). Visual evaluation was made according to the following criteria.
A: There is no peeling, floating, or foaming between the adhesive optical film and the alkali-free glass.
X: There exists peeling, floating, and foaming between the adhesive optical film and the alkali-free glass.

(Handling properties)
The obtained adhesive optical film was punched using a press. At that time, the state of the cutting blade was visually evaluated according to the following criteria.
○: When the adhesive is not removed by the cutting blade.
X: When the adhesive is removed or adhered by the cutting blade.

  In Table 1, BA: n-butyl acrylate, PEA: phenoxyethyl acrylate, HBA: 4-hydroxybutyl acrylate, BzA: benzyl acrylate, AA: acrylic acid are shown. Further, KBM573: N-phenyl-γ-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Silicone, KBM573), KBM403: 3-gridoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicone, KBM403), KBM803: 3-mercapto 1 shows propyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., KBM403).

It is sectional drawing of an example of the adhesive optical film of this invention. It is sectional drawing of an example of the adhesive optical film of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent base film 2 Alignment film 3 Discotic liquid crystal layer 4 Undercoat layer 5 Adhesive layer 6 Polarizer 7 Transparent protective film

Claims (9)

In the pressure-sensitive adhesive optical film in which the pressure-sensitive adhesive layer is provided on the discotic liquid crystal layer of the optical film having the discotic liquid crystal layer on one side of the transparent substrate film via the undercoat layer,
The undercoat layer contains polymers and an antioxidant,
The pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive containing an acrylic polymer, a crosslinking agent and a silane coupling agent,
Acrylic polymers are used as monomer units.
49.9 to 84.9% by weight of alkyl (meth) acrylate (a1),
15 to 50% by weight of (meth) acrylate (a2) having an aromatic ring structure, and 0.1 to 5% by weight of monomer (a3) excluding component (a1) and component (a2) ,And,
The acrylic polymer has a weight average molecular weight (Mw) of 1.4 to 2.5 million and a dispersity (Mw / Mn) of 3 to 10 which is a value obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn). A pressure-sensitive adhesive optical film.   The pressure-sensitive adhesive optical film according to claim 1, wherein the polymer of the undercoat layer is a polymer having a primary amino group.   The pressure-sensitive adhesive optical film according to claim 1 or 2, wherein the antioxidant is at least one selected from phenol-based, phosphorus-based, sulfur-based and amine-based antioxidants.   The pressure-sensitive adhesive optical film according to claim 1, wherein the undercoat layer contains 0.01 to 1000 parts by weight of an antioxidant with respect to 100 parts by weight of the polymers.   The pressure-sensitive adhesive optical film according to any one of claims 1 to 4, wherein the silane coupling agent has an alkoxysilyl group and an aromatic ring structure in the molecule.   The pressure-sensitive adhesive optical film according to claim 5, wherein the silane coupling agent is an amino group-containing silane coupling agent having an aromatic ring structure.   The pressure-sensitive adhesive optical film according to claim 1, wherein the amount of the silane coupling agent is 0.01 to 5 parts by weight with respect to 100 parts by weight of the acrylic polymer.   The pressure-sensitive adhesive optical film according to claim 1, wherein a polarizer is laminated on one side of the transparent base film on the side where the discotic liquid crystal layer is not formed. An image display device using the adhesive optical film according to claim 1.