JP2008250335A - Adhesive type optical film for bonding glass substrate of liquid crystal panel, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive type optical film for bonding glass substrates of a liquid crystal panel, which comprises a water dispersion type bonding agent as a bonding agent layer disposed on at least a surface of the optical film, and which has high adhesive strength toward a glass plate, and a liquid crystal display device equipped with the adhesive type optical film. <P>SOLUTION: The adhesive type optical film for bonding the glass substrates of the liquid crystal panel comprises the water dispersion type bonding agent as the bonding agent layer, composed of a water dispersion obtained with emulsion polymerization of a monomer mixture with at least an alkyl (meth)acrylate as a main component and a silane-based monomer, disposed on at least a surface of the optical film, wherein 0.005-1 pts.wt. silane-based monomer is included therein with respect to 100 pts.wt. monomer mixture, and is characterized in that it has the adhesive strength, measured after bonded to the glass plate to be bonded and after seven days of storing at 70°C and 20% RH, to be 1.5 times or more of the initial value. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive optical film for attaching a liquid crystal panel to a glass substrate, which is useful for bonding the liquid crystal panel to the glass substrate. Furthermore, the present invention relates to a liquid crystal display device using the adhesive optical film. Examples of the optical film include a polarizing film, a retardation film, an optical compensation film, a brightness enhancement film, an antiglare sheet, or a film in which a plurality of these films are laminated.

  Conventional pressure-sensitive adhesive sheets are widely used for bonding and fixing to various adherends such as paper, cardboard, plastic material, wood, and metal. Among them, acrylic pressure-sensitive adhesives have been widely used in place of conventional rubber-based pressure-sensitive adhesives in terms of their excellent adhesive properties and weather resistance. For acrylic adhesives, solvent-type acrylic adhesives have mainly been used, but since these solvent-type acrylic adhesives are synthesized in organic solvents, the volatilization of the solvent during coating is environmentally There is a problem, and conversion to water-dispersed acrylic pressure-sensitive adhesive is being attempted.

  The pressure-sensitive adhesive sheet using the water-dispersed acrylic pressure-sensitive adhesive does not use a solvent, and therefore has an advantage that it is desirable for environmental hygiene and is excellent in solvent resistance. In general, this pressure-sensitive adhesive sheet is prepared by adding a cross-linking agent after the polymerization of a monomer mixture containing an acrylic monomer as a main component in order to adjust the solvent insoluble matter that affects the holding power and the like of the pressure-sensitive adhesive layer. It is manufactured by preparing a composition and applying it onto a substrate. However, with the pressure-sensitive adhesive sheet obtained in this way, it is difficult to obtain a high adhesive force to the glass plate, and satisfactory characteristics have not been obtained so far.

  In recent years, liquid crystal displays have become widespread as new display devices. In the liquid crystal display, it is indispensable to arrange polarizing elements on both sides of the glass substrate that forms the outermost surface of the liquid crystal panel because of its image forming method. Generally, a polarizing film is attached to the outermost surface of the liquid crystal panel. ing. In addition to the polarizing film, various optical elements have been used on the outermost surface of the liquid crystal panel in order to improve the display quality of the display. For example, a retardation film 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 sticking the optical film on the outermost surface of the liquid crystal panel, an adhesive is usually used. In addition, since the optical film can be instantly fixed to the outermost surface of the liquid crystal panel and has a merit that a drying process is not required to fix the optical film, the adhesive is preliminarily applied to one side of the optical film. It is provided as a layer. That is, an adhesive optical film is generally used for attaching the optical film to the outermost surface of the liquid crystal panel. As the pressure-sensitive adhesive, acrylic pressure-sensitive adhesives that are excellent in terms of adhesiveness, transparency, weather resistance and the like are frequently used.

  Further, the optical film pressure-sensitive adhesive may be required to have a property that it can be bonded (reworked). This is because when the optical film is bonded to the outermost surface of the liquid crystal panel, the bonding position is often wrong, or foreign objects are often caught in the bonding surface. In such cases, the optical film is peeled off from the uppermost surface of the liquid crystal panel. This is a characteristic required to enable pasting again. In this case, the liquid crystal panel is expensive and reused, but the relatively inexpensive optical film is discarded.

About the said rework property, the adhesive force with respect to the glass substrate of the outermost surface of a liquid crystal panel needs to be lower. However, as liquid crystal displays become widespread in various fields such as measuring instruments, electronic watches and televisions, and in-vehicle devices, the adhesion between optical films and liquid crystal panels increases as the opportunity for use under harsh conditions increases. It is required that the adhesion through the agent layer has an adhesive strength that can sufficiently withstand use in a hot and humid atmosphere. Therefore, the adhesive strength is low enough to allow rework at the beginning of pasting, and after that, even in a hot and humid atmosphere, it adheres firmly so that it does not float or peel off at the interface between the pressure-sensitive adhesive layer and the liquid crystal cell. An adhesive is desired.
Japanese Unexamined Patent Publication No. 07-26229 JP 2001-55550 A

  Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive optical film for adhering to a glass substrate of a liquid crystal panel in which a pressure-sensitive adhesive layer made of an acrylic water-dispersed pressure-sensitive adhesive is laminated, and the adhesive strength increases with time. It aims at providing the liquid crystal display device by which the said adhesive type optical film is arrange | positioned through the adhesive layer on the glass substrate surface of a liquid crystal panel.

  As a result of intensive investigations to achieve the above-mentioned object, the present inventors have copolymerized a silane monomer and an aqueous system in a monomer mixture mainly composed of an aqueous (meth) acrylic acid alkyl ester. The water-dispersed pressure-sensitive adhesive containing the water dispersion obtained in this way has acquired the knowledge that the adhesive strength increases with the passage of time and a strong bonding force is expressed, and the present invention has been completed.

  That is, the present invention uses, as an adhesive layer, an aqueous dispersion type adhesive comprising an aqueous dispersion obtained by emulsion polymerization of a monomer mixture containing at least a (meth) acrylic acid alkyl ester as a main component and a silane monomer. A pressure-sensitive adhesive optical film for attaching a glass substrate of a liquid crystal panel provided on at least one surface on an optical film, comprising 0.005 to 1 part by weight of a silane monomer with respect to 100 parts by weight of the monomer mixture, Adhesive type for adhering to a glass substrate of a liquid crystal panel, wherein the adhesive strength after storage at 70 ° C., 20% RH and 7 days is 1.5 times or more of the initial value after adhering to a glass plate adherend The present invention relates to an optical film (claim 1).

  The present invention also relates to a liquid crystal display device (Claim 2) in which the adhesive optical film is disposed on a glass substrate surface of a liquid crystal panel via an adhesive layer.

  According to the present invention, water containing an aqueous dispersion obtained by adding a silane monomer to a monomer mixture mainly composed of an aqueous dispersion type (meth) acrylic acid alkyl ester and copolymerizing in an aqueous system. By using a pressure-sensitive adhesive film as a pressure-sensitive adhesive layer on a liquid crystal panel provided on an optical film, the adhesive strength of the liquid crystal panel attached to the glass substrate is increased over time, and the adhesive strength increases with time. An adhesive optical film for attaching a glass substrate to a liquid crystal panel can be provided. Furthermore, it is possible to provide a pressure-sensitive adhesive optical film and a liquid crystal display device excellent in heat resistance and moisture resistance that do not float or peel off at the interface between the pressure-sensitive adhesive layer and the liquid crystal cell even in a high-temperature and high-humidity atmosphere. .

  The present invention uses an aqueous dispersion type adhesive comprising an aqueous dispersion obtained by emulsion polymerization of a monomer mixture containing at least a (meth) acrylic acid alkyl ester as a main component and a silane monomer as an adhesive layer. It is an adhesive optical film for attaching a glass substrate of a liquid crystal panel provided on at least one side of the film.

The (meth) acrylic acid alkyl ester used as the main constituent monomer in the present invention is represented by the general formula (1).
CH ₂ = C (R ¹ ) COOR ² (1)
(Wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 2 to 14 carbon atoms).

Examples of R ² include ethyl, propyl, isopropyl, butyl, isobutyl, isoamyl, hexyl, heptyl, 2-ethylhexyl, isooctyl, isononyl, and isodecyl. Among these, R ² is preferably an alkyl group having 2 to 10 carbon atoms such as a butyl group or a 2-ethylhexyl group. The said (meth) acrylic-acid alkylester can be used individually or in mixture of 2 or more types. For example, butyl acrylate alone or a combination of butyl acrylate and 2-ethylhexyl acrylate can be used as the alkyl acrylate ester. In this case, the ratio of 2-ethylhexyl acrylate to butyl acrylate is about the former / the latter = 0/100 to 55/45 (for example, 5/95 to 60/40).

The proportion of the (meth) acrylic acid alkyl ester [for example, the above (meth) acrylic acid C _2-14 alkyl ester] in the monomer mixture mainly composed of (meth) acrylic acid alkyl ester is generally 80% by weight. It is more than (for example, about 80 to 99.8% by weight), preferably 85% by weight or more (for example, about 85 to 99.5% by weight), and more preferably 90% by weight or more (for example, about 90 to 99% by weight).

  The monomer mixture usually contains a functional group-containing monomer (thermally crosslinkable functional group-containing monomer) in order to introduce a crosslinking point for thermal crosslinking. By using the functional group-containing monomer as a comonomer component, adhesion to an adherend is also improved.

  Examples of the functional group-containing monomer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, and maleic anhydride, or acid anhydrides thereof; (meth) acrylic acid 2 Hydroxyl group-containing monomers such as hydroxyethyl, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol ( Amide group-containing monomers such as (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide; dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, etc. Amino group-containing monomers; glycidyl such as glycidyl (meth) acrylate Containing monomers; (meth) acrylonitrile, N- (meth) acryloyl morpholine, N- vinyl-2-pyrrolidone. Among these, carboxyl group-containing monomers such as acrylic acid or acid anhydrides thereof are preferable. One or more of the above functional group-containing monomers can be used.

  The usage-amount of the said functional group containing monomer is 0.5-12 weight part with respect to 100 weight part of said (meth) acrylic-acid alkylesters, Preferably it is about 1-8 weight part.

  In addition, the monomer mixture may contain other copolymerizable monomers as necessary in order to enhance characteristics such as cohesive force. Examples of such copolymerizable monomers include methyl (meth) acrylate: vinyl esters such as vinyl acetate; aromatic vinyl compounds such as styrene and vinyl toluene; cyclopentyl di (meth) acrylate, isobornyl (meta ) (Meth) acrylic esters of cyclic alcohols such as acrylate; neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, And (meth) acrylic acid esters of polyhydric alcohols such as tetramethylol methane tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate. These copolymerizable monomers can also be used alone or in combination of two or more.

  In the present invention, the silane monomer copolymerized with the (meth) acrylic acid alkyl ester is not particularly limited as long as it is a polymerizable compound having a silicon atom. A silane compound having a (meth) acryloyl group such as a (meth) acryloyloxyalkylsilane derivative is preferable in terms of excellent polymerizability. Examples of the silane monomer include 3-methacryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltriethoxysilane, and 3-methacryloyloxy. Examples include propylmethyldimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-acryloyloxypropylmethyldiethoxysilane. These silane monomers can be used alone or in combination of two or more.

  In addition to the above, as copolymerizable silane monomers, for example, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltri Methoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane and the like can also be used. .

  The amount of the silane monomer can be appropriately selected according to the type and use of the (meth) acrylic acid alkyl ester, but the copolymerization amount of the silane monomer is mainly the (meth) acrylic acid alkyl ester. For 100 parts by weight of the monomer mixture (excluding silane monomers) as the component, the adhesive strength may be reduced to the extent that it cannot be adhered if it exceeds 1 part by weight. Cohesive force tends to decrease due to insufficient polymer strength. Therefore, in the present invention, the amount of the silane monomer relative to 100 parts by weight of the monomer mixture (excluding the silane monomer) is 0.005 to 1 part by weight, preferably 0.01 to 0. 0.5 parts by weight, and more preferably in the range of 0.03 to 0.1 parts by weight.

  In this invention, a crosslinking agent can be used according to the use of an adhesive. As the crosslinking agent, a commonly used crosslinking agent can be used, and examples thereof include an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent. The cross-linking agent may be either oil-soluble or water-soluble.

  The water-dispersed pressure-sensitive adhesive composition of the present invention is obtained, for example, by subjecting a monomer mixture containing the (meth) acrylic acid alkyl ester as a main component and a silane monomer to conventional emulsion polymerization, ) It can be prepared by obtaining an aqueous dispersion of an acrylic acid ester copolymer and adding the cross-linking agent as necessary.

  As the polymerization method, general batch polymerization, continuous dropping polymerization, divided dropping polymerization, or the like can be employed, and the polymerization temperature is, for example, about 20 to 100 ° C.

  Examples of the polymerization initiator used for the polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (2-amidino). Propane) dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), etc. Azo initiators; persulfates such as potassium persulfate and ammonium persulfate; peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; substituted ethane initiators such as phenyl substituted ethane Agent; aromatic carbonyl compound; combination of persulfate and sodium bisulfite, peroxide and sodium ascorbate And redox initiators such as combinations with but are exemplified, but the invention is not limited thereto. The amount of the polymerization initiator used is, for example, about 0.005 to 1 part by weight with respect to 100 parts by weight of the total amount of monomers.

  Moreover, you may use a chain transfer agent for superposition | polymerization. Examples of chain transfer agents include conventional chain transfer agents such as mercaptans such as dodecanethiol. The amount of chain transfer agent used is, for example, about 0.001 to 0.5 parts by weight with respect to 100 parts by weight of the total amount of monomers.

  In addition, as an emulsifier, anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate; polyoxy Nonionic emulsifiers such as ethylene alkyl ether and polyoxyethylene alkyl phenyl ether can be used. These emulsifiers may be used independently and may use 2 or more types together. The amount of the emulsifier used is, for example, about 0.2 to 10 parts by weight, preferably about 0.5 to 5 parts by weight with respect to 100 parts by weight of the total amount of monomers.

  In addition to the above method, the water-dispersed pressure-sensitive adhesive composition is obtained by obtaining the (meth) acrylic acid ester copolymer by a method other than emulsion polymerization, and then adding the cross-linking agent as necessary. It may be prepared by dispersing in water.

  A tackifier component can also be mixed in the water-dispersed pressure-sensitive adhesive composition of the present invention. Examples of tackifying components that can be mixed include rosin resins, terpene resins, aliphatic petroleum resins, aromatic petroleum resins, copolymer petroleum resins, alicyclic petroleum resins, xylene resins and elastomers. it can.

  For water-dispersed PSA compositions, other bases (such as ammonia water) and acids for adjusting pH, acids, and additives usually used for PSA, such as surfactants and anti-aging Agents, fillers, pigments, colorants and the like may be added.

  The pressure-sensitive adhesive optical film for attaching a glass substrate of the liquid crystal panel of the present invention is a pressure-sensitive adhesive optical film provided on at least one surface of the optical film with the water-dispersed pressure-sensitive adhesive composition as a pressure-sensitive adhesive layer. As the substrate, for example, a polypropylene film, an ethylene-propylene copolymer film, a polyester film, a plastic film such as polyvinyl chloride, paper such as kraft paper, metal foil, or the like can be used. The plastic film may be an unstretched film or a stretched (uniaxially stretched or biaxially stretched) film. Further, the surface of the base material to which the pressure-sensitive adhesive is applied may be subjected to a surface treatment such as a commonly used primer or a corona discharge method. Although the thickness of a base material can be suitably selected according to the objective, generally it is about 10-500 micrometers. Moreover, the shape can be processed and used for arbitrary shapes, such as a tape form, a sheet form, and a film form.

  The water-dispersed pressure-sensitive adhesive composition can be applied using a conventional coater such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater and the like. The water-dispersed pressure-sensitive adhesive composition is applied such that the thickness of the pressure-sensitive adhesive layer after drying is, for example, about 10 to 100 μm.

  The adhesive optical film for attaching the glass substrate of the liquid crystal panel of the present invention has an adhesive strength to the glass plate adherend after adhering to the glass plate adherend, 70 ° C., 20% RH, adhesion after storage for 7 days. The force is 1.5 times or more of the initial value, preferably 1.7 times or more (usually 10 times or less). Here, the initial value of the adhesive strength refers to an adhesive strength measured after being attached to a glass plate adherend and left at 23 ° C. for 30 minutes.

  By setting the adhesive strength over time to 1.5 times or more of the initial value, preferably 1.7 times or more (usually 10 times or less), it is possible to bond more firmly over time, and a high temperature and humidity atmosphere Even when used underneath, the adhesive strength is increased, so that no floating or peeling occurs.

  In the pressure-sensitive adhesive optical film for attaching a glass substrate of the liquid crystal panel of the present invention, when used for an application requiring particularly high adhesive strength, the initial adhesive strength to a glass plate adherend is 15 N / 20 mm or more, preferably It is desirable to set it to 17N / 20mm or more (usually 30N / 20mm or less). If the initial adhesion to the glass plate adherend is 15 N / 20 mm or more and the adhesive strength over time is 1.3 times or more than the initial value, sufficient adhesion to the glass plate adherend from the beginning In addition, it can be more firmly bonded over time.

  On the other hand, when it is used for an application where reworkability is required, an initial adhesive strength as weak as temporary fixing is required. For this reason, it is desirable that the initial adhesive force to the glass plate adherend is about 4 N / 20 mm to 10 N / 20 mm, preferably about 5 N / 20 mm to 9 N / 20 mm. By setting in this way, the adhesive strength is low enough to allow rework at the beginning of pasting, and then the adhesive strength rises, and even in a hot and humid atmosphere, it floats and peels at the interface between the pressure-sensitive adhesive layer and the liquid crystal cell. It can be firmly bonded so that it does not occur.

  In the present invention, an optical film is used as a support for the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive optical film for adhering a glass substrate of a liquid crystal panel, and the pressure-sensitive adhesive optical film on the glass substrate surface of the liquid crystal panel A liquid crystal display device is provided.

  As shown in FIG. 1, the pressure-sensitive adhesive optical film of the present invention is provided with a pressure-sensitive adhesive layer 2 made of the water-dispersed pressure-sensitive adhesive for glass plates. A release sheet 3 can be provided on the pressure-sensitive adhesive layer 2.

  As the optical film 1, one used for forming a liquid crystal display device or the like is used, and the type thereof is not particularly limited. For example, examples of the optical film include a polarizing film, a retardation film, an optical compensation film, a brightness enhancement film, and an antiglare sheet.

  It does not restrict | limit especially as a polarizer which comprises a polarizing film, Various things can be used. Examples of the polarizer include dichroic substances such as 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 a polyene-based oriented film such as a stretched product obtained by adsorbing a substance, a dehydrated polyvinyl alcohol product or a dehydrochlorinated polyvinyl chloride product. The thickness of the polarizer is not particularly limited, but is generally about 5 to 80 μm.

  On one or both sides of the polarizer, a transparent protective layer can be provided as a coating layer made of a polymer or a laminate layer of a film for the purpose of water resistance. As the transparent polymer or film material for forming the transparent protective layer, an appropriate transparent material can be used, but a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property and the like is preferably used. Although the thickness in particular of a transparent protective layer is not restrict | limited, About 10-300 micrometers is common.

  Examples of the material for forming the transparent protective layer include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as cellulose diacetate and cellulose triacetate, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile, Examples thereof include styrene polymers such as styrene copolymers (AS resins), polycarbonate polymers, 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 the polymer that forms the transparent protective layer.

  Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer film, and the like. The thickness of the retardation film is not particularly limited, but is generally about 20 to 150 μm. The retardation plate can also be formed as a superposed body of stretched films of two or more layers and controlled optical characteristics such as retardation, and the liquid crystal cell is used for the purpose of preventing coloring and expanding the viewing angle range. It can also be used as an elliptically polarizing film formed by laminating with a polarizing film in order to compensate for the phase difference.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose polymer, or binary, ternary copolymers, graft copolymers, blends Things are given. These polymer materials become oriented products (stretched films) by stretching or the like.

  Examples of the liquid crystalline polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of the main chain type liquid crystalline polymer include, for example, a nematic-oriented polyester-based liquid crystalline polymer having a structure in which a mesogenic group is bonded at a spacer portion imparting flexibility. Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystalline polymers are prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment surface such as those obtained by rubbing the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or by obliquely depositing silicon oxide. This is done by developing and heat treatment.

  The polarizing film and the retardation film can be laminated and used, for example, a reflective polarizing film, a semi-transmissive layer polarizing film, and a polarized light separating polarizing film. Moreover, the optical film of the said illustration can also be used as an optical compensation film and other various viewing angle expansion films, Furthermore, a brightness improvement film etc. are mention | raise | lifted as an optical film. Moreover, a polarizing film can also provide an anti-glare sheet | seat by providing the reflection layer of a fine uneven structure on the surface.

  The pressure-sensitive adhesive layer 2 is formed on one side of the optical film 1 to be attached to the glass substrate of the liquid crystal panel. The forming method is not particularly limited, and the above-described method can be used. By the method of applying a pressure-sensitive adhesive composition (aqueous dispersion) to the optical film 1 and drying, the release sheet 3 provided with the pressure-sensitive adhesive layer 2 is used. For example, a transfer method. The pressure-sensitive adhesive layer 2 (dry film thickness) is not particularly limited in thickness, but is preferably about 10 to 40 μm.

  In addition, as a constituent material of the release sheet 3, synthetic resin films, such as paper, polyethylene, a polypropylene, a polyethylene terephthalate, etc. are mention | raise | lifted. The surface of the release sheet 3 may be subjected to a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment, if necessary, in order to enhance the peelability from the pressure-sensitive adhesive layer 2.

  A liquid crystal display device can be manufactured by disposing the optical film thus obtained on the glass substrate surface of the liquid crystal panel via an adhesive layer. Under the present circumstances, you may laminate | stack two or more types of optical films which have an adhesive layer. The liquid crystal display device may be formed by a method in which a pressure-sensitive adhesive is directly applied between the optical film and the liquid crystal cell, and a pressure-sensitive adhesive layer having a single layer or a laminated structure is provided.

  The following examples further illustrate the present invention in detail but are not to be construed to limit the scope thereof. “Parts” and “%” are based on weight unless otherwise specified.

Example 1
Using a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 90 parts of butyl acrylate, 10 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid, 3-methacryloyloxypropyltriethoxysilane (Shin-Etsu Silicone Co., Ltd.) "KBE-503" manufactured by company) 0.06 part, 0.05 part of dodecanethiol (chain transfer agent), 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane]] After 0.1 parts of dihydrochloride (initiator) is added to 100 parts of water to which 1.5 parts of sodium polyoxyethylene lauryl sulfate (emulsifier) is added, emulsion polymerization is performed, and then 10% by weight ammonium water is added to adjust the pH to 8. It was adjusted. 30 parts of rosin resin ("Superester E-100" manufactured by Arakawa Chemical Co., Ltd.) as a tackifier was added to 100 parts of the solid part of the aqueous dispersion as a solid content to obtain a water-dispersed adhesive. . This was applied to a PET (polyethylene terephthalate) film having a thickness of 40 μm, dried at 120 ° C. for 3 minutes, and a pressure-sensitive adhesive layer having a thickness of 50 μm was provided to prepare a pressure-sensitive adhesive sheet. The solvent insoluble content at this time was 42%.

Example 2
10 wt% ammonium water was prepared by emulsion polymerization with the same formulation as in Example 1 except that the amount of 3-methacryloyloxypropyltriethoxysilane (“KBE-503” manufactured by Shin-Etsu Silicone Co., Ltd.) was 0.04 part. Was added to adjust the pH to 8. To this, 0.07 part of tris (epoxypropyl) isocyanurate as a cross-linking agent and rosin resin (“Superester E-100” manufactured by Arakawa Chemical Co., Ltd.) as a tackifier with respect to 100 parts of the solid part of the aqueous dispersion. 30 parts of solid content was added to obtain a water-dispersed pressure-sensitive adhesive. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. The solvent insoluble content at this time was 45%.

Example 3
10 wt% ammonium water was prepared by emulsion polymerization with the same composition as in Example 1 except that the amount of 3-methacryloyloxypropyltriethoxysilane ("KBE-503" manufactured by Shin-Etsu Silicone Co., Ltd.) was 0.02 part. Was added to adjust the pH to 8. To this, 100 parts of the solid part of the aqueous dispersion was mixed with 0.13 part of tris (epoxypropyl) isocyanurate as a crosslinking agent and rosin resin (“Superester E-100” manufactured by Arakawa Chemical Industries, Ltd.) as a tackifier. 30 parts of solid content was added to obtain a water-dispersed pressure-sensitive adhesive. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. The solvent insoluble content at this time was 42%.

Comparative Example 1
Without adding 3-methacryloyloxypropyltriethoxysilane, the other components were emulsion-polymerized in the same manner as in Example 1, and adjusted to pH 8 by adding 10 wt% ammonium water. To this, 100 parts of the solid part of the aqueous dispersion was mixed with 0.14 part of tris (epoxypropyl) isocyanurate as a crosslinking agent and rosin resin (“Superester E-100” manufactured by Arakawa Chemical Industries, Ltd.) as a tackifier. 30 parts of solid content was added to obtain a water-dispersed pressure-sensitive adhesive. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. The solvent insoluble content at this time was 42%.

Comparative Example 2
The emulsion polymerization was carried out in the same manner as in Example 1 except that the amount of 3-methacryloyloxypropyltriethoxysilane (“KBE-503” manufactured by Shin-Etsu Silicone Co., Ltd.) was 1.2 parts, and 10% by weight ammonium water Was added to adjust the pH to 8. 30 parts of rosin resin ("Superester E-100" manufactured by Arakawa Chemical Co., Ltd.) as a tackifier was added to 100 parts of the solid part of the aqueous dispersion as a solid content to obtain a water-dispersed adhesive. . A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. The solvent-insoluble content at this time was 90%.

  The following characteristics of the pressure-sensitive adhesives and pressure-sensitive adhesive sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were examined. The results are shown in Table 1.

(Solvent insoluble matter)
The water-dispersed pressure-sensitive adhesives of Examples and Comparative Examples were coated on a release liner and dried under the same drying conditions as in Examples to obtain pressure-sensitive adhesives. A predetermined amount (about 0.1 g) of a sample is precisely weighed from this pressure-sensitive adhesive (of which the non-volatile content is W ₁ mg) and immersed in about 40 g of ethyl acetate at room temperature for 1 week, then insoluble. The product was taken out, this insoluble matter was dried at 100 ° C. for 2 hours, the weight (W ₂ mg) was measured, and the insoluble matter (wt%) = (W ₂ / W ₁ ) × 100 was calculated according to the following formula.

(Adhesive strength)
After the pressure-sensitive adhesive sheet coated on the PET film is cut into a size of 20 mm × 100 mm, it is bonded to a glass plate by reciprocating a 2 kg-weight rubber roller once and left at 23 ° C. for 30 minutes. The adhesive strength was measured in an atmosphere of 65 ° C. and 65% RH, and this was taken as the initial value. After bonding, the film was allowed to stand at 70 ° C. and 20% RH for 7 days, and then the adhesive strength was measured in an atmosphere of 23 ° C. and 65% RH. The measurement was performed on the sample with a tensile tester at a peeling angle of 180 ° and a peeling speed of 300 mm / min.

(Humidification test)
After the adhesive polarizing film was cut into a size of 200 mm × 150 mm, the release paper was peeled off, and then bonded onto a glass plate and left in an atmosphere of 50 ° C. × 0.5 Mpa for 15 minutes. This sample was subjected to 60 ° C./90% R.D. H. It was visually confirmed whether or not defects such as floating and peeling occurred when left in the atmosphere for 500 hours. The case where a defect occurred was marked as ◯, and the case where a defect did not occur was marked as x.

As is clear from the examples, the adhesive optical film for adhering the glass substrate of the liquid crystal panel of the present invention has an adhesive strength after storage at 70 ° C., 20% RH for 7 days after being adhered to the glass plate adherend. The initial value is 1.5 times or more, and the initial value of the adhesive strength is 15 N / 20 mm or more, and even in a high temperature and high humidity atmosphere, floating or peeling may occur at the interface between the pressure-sensitive adhesive layer and the glass substrate. It can be seen that excellent heat resistance and moisture resistance are exhibited. On the other hand, Comparative Example 1 which does not contain any silane monomer in the pressure-sensitive adhesive layer is insufficient in the increase in adhesive strength over time, and is a comparison in which a silane monomer is contained in a specific value or more. In Example 2, since the degree of crosslinking was high, the increase in adhesive strength over time was insufficient, and floating and peeling occurred at the interface between the pressure-sensitive adhesive layer and the glass substrate in a hot and humid atmosphere.

It is sectional drawing of the adhesion type optical film of this invention.

Explanation of symbols

1 Optical film 2 Adhesive layer 3 Release sheet

Claims (2)

At least on the optical film, a water-dispersed adhesive comprising an aqueous dispersion obtained by emulsion polymerization of a monomer mixture containing at least a (meth) acrylic acid alkyl ester as a main component and a silane monomer is used as an adhesive layer. It is an adhesive optical film for attaching a glass substrate of a liquid crystal panel provided on one side,
It contains 0.005 to 1 part by weight of a silane monomer with respect to 100 parts by weight of the monomer mixture, and after adhering to a glass plate adherend, the adhesive strength after storage at 70 ° C., 20% RH for 7 days A pressure-sensitive adhesive optical film for attaching a glass substrate of a liquid crystal panel, which is 1.5 times or more of an initial value. A liquid crystal display device comprising the pressure-sensitive adhesive optical film according to claim 1 disposed on a glass substrate surface of a liquid crystal panel via a pressure-sensitive adhesive layer.