JP5354691B2 - Adhesive layer - Google Patents

Description

  The present invention relates to an adhesive optical film in which an adhesive layer for adhering an optical film to a glass substrate of a liquid crystal panel is laminated on one surface of the optical film. 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.

  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 such that a drying process is not required to fix the optical film, the adhesive is preliminarily attached to one side of the optical film. It is provided as. That is, an adhesive optical film is generally used for attaching the optical film to the outermost surface of the liquid crystal panel.

  The adhesive optical film is bonded to the outermost surface of the liquid crystal panel. At that time, if the bonding position is wrong or a foreign object bites into the bonding surface, the optical film is peeled off from the outermost surface of the liquid crystal panel and reused. However, when the optical film is peeled off, if the peeling is heavy, the liquid crystal panel may be damaged such as a cell gap, or an adhesive residue may be left on the liquid crystal panel surface. Moreover, the adhesiveness of the adhesive layer of the adhesive optical film bonded to a liquid crystal panel usually increases with time. In addition, panel manufacturers have a condition in which temperature is applied in each process, and a liquid crystal panel on which an optical film is bonded is not necessarily placed at a constant temperature. Therefore, the adhesive optical film can be easily peeled off and pasted (reworked) again after passing through each process and after a long time after being bonded to the liquid crystal panel. Is required.

  On the other hand, the pressure-sensitive adhesive optical film bonded to the outermost surface of the liquid crystal panel needs to be durable so as not to be foamed or peeled even in use under heating and humidification conditions. As described above, the pressure-sensitive adhesive optical film is required to satisfy the contradictory properties of durability and performance (reworkability) such as easy peeling.

  Conventionally, as a means for improving the reworkability of the pressure-sensitive adhesive optical film, there is a method of reducing the adhesion area of the pressure-sensitive adhesive layer. As a means for that, there is a method of reducing the adhesion area in such a manner that the adhesive layer is formed by alternately coating the adhesive layer and the non-adhesive layer in a streaked pattern. When the adhesion area is reduced in this way, the rework is good. However, a decrease in the adhesion area of the pressure-sensitive adhesive layer works in a disadvantageous direction with respect to durability related to foaming and peeling during heating and humidification. Therefore, if reworkability is improved by the above method, peeling occurs during heating and humidification. This foaming or peeling is considered to occur because the optical film is deformed by expansion or contraction when heated or humidified, and stress generated by the deformation acts on the interface between the adhesive and the liquid crystal cell.

  An object of the present invention is to provide a pressure-sensitive adhesive layer formed on an optical film, which is excellent in both reworkability and durability.

  The present inventors have intensively studied to solve the above-mentioned problems. As a result, they have found that the above object can be achieved by the following adhesive layer, and have completed the present invention.

  That is, the present invention is an adhesive layer formed on one surface of an optical film, wherein the adhesive layer is formed of acrylic polymer and fine particles as a main component of the resin layer, and the particle size of the fine particles is 1 to 10 μm (excluding the case of 1 μm) and 1 to 50 parts by weight of fine particles with respect to 100 parts by weight of the acrylic polymer, and the haze value of the adhesive layer is 10% It is related with the adhesion layer characterized by the following.

  The pressure-sensitive adhesive layer of the present invention is formed of a resin layer mainly composed of an acrylic polymer and fine particles. The fine particles are dispersed in the resin layer, and both the durability and the reworkability are achieved by the fine particles. That is, since the fine particles are non-tacky, the fine particles existing on the surface of the pressure-sensitive adhesive layer reduce the adhesion of the portion, and the adhesion area between the pressure-sensitive adhesive layer and the glass substrate of the liquid crystal panel is reduced, and the reworkability is improved. It is thought. When the adhesion area is reduced by dispersing the fine particles in the adhesive layer, the stress generated by deformation such as expansion and contraction of the optical film during heating and humidification is dispersed at the interface between the fine particles and the adhesive layer. Since the stress at the liquid crystal cell interface is reduced, the durability is also satisfied.

  In the pressure-sensitive adhesive optical film of the present invention, it is preferable that the pressure-sensitive adhesive layer has an adhesive force to glass of 10 N / 25 mm or less. The reworkability is good when the adhesive layer has an adhesive strength to glass of 10 N / 25 mm or less, and the required performance can be satisfied in terms of durability. The adhesion strength of the adhesive layer to glass is more preferably 5 N / 25 mm or less from the viewpoint of reworkability. On the other hand, from the viewpoint of durability, it is preferably 1 N / 25 mm or more.

  In the pressure-sensitive adhesive optical film, the pressure-sensitive adhesive layer preferably contains 1 to 50 parts by weight of fine particles with respect to 100 parts by weight of an acrylic polymer that is a main component of the resin layer.

  The content of the fine particles is not particularly limited, but is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the acrylic polymer. When the content of the fine particles is reduced, the degree of decrease in the adhesion area is reduced. Therefore, the content of the fine particles is preferably 5 parts by weight or more, more preferably 10 parts by weight or more for improving reworkability. On the other hand, when the content of the fine particles increases, the adhesion area decreases remarkably. Therefore, in order to satisfy the durability, the content of the fine particles is preferably 40 parts by weight or less, and more preferably 30 parts by weight or less. The content of the fine particles is preferably 5 to 40 parts by weight, and more preferably 10 to 30 parts by weight.

  In the pressure-sensitive adhesive optical film, the haze value of the pressure-sensitive adhesive layer is preferably 10% or less.

  Since the pressure-sensitive adhesive optical film of the present invention is attached to a glass substrate of a liquid crystal panel, the pressure-sensitive adhesive layer is preferably transparent, and the haze value of the pressure-sensitive adhesive layer is 10% or less, and further 5% or less. Is preferred.

  Furthermore, the present invention relates to a liquid crystal display device using the adhesive optical film. The pressure-sensitive adhesive optical film of the present invention is used by being bonded to a glass substrate on the outermost surface of a liquid crystal panel.

  In addition, as a technique for incorporating fine particles into the adhesive layer related to the optical film, JP-A-11-30714, JP-A-11-80688, JP-A-11-223712, and the like are disclosed. However, the pressure-sensitive adhesive layers described in these publications are all pressure-sensitive adhesive layers for bonding optical films to each other or their protective films, and are not pressure-sensitive adhesive layers for bonding to a glass substrate of a liquid crystal panel. The adhesive layer described in these publications contains particles having a refractive index different from that of the adhesive layer, and is intended to impart diffusibility to the adhesive layer. The adhesive layer has durability and reworkability. It is not intended to be compatible, nor is transparency required for the adhesive layer.

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

  In the pressure-sensitive adhesive layer of the pressure-sensitive adhesive optical film of the present invention, a resin layer is formed from a pressure-sensitive adhesive mainly composed of an acrylic polymer. The acrylic polymer is obtained by polymerization using an alkyl (meth) acrylate as a main monomer, or by copolymerizing another copolymerizable monomer. Further, the acrylic polymer may be a polymer obtained by further modifying a functional group introduced from a copolymerization monomer. (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

  The average carbon number of the alkyl group of the alkyl (meth) acrylate constituting the main skeleton of the acrylic polymer is about 1 to 12, and specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (Meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like can be exemplified, and these can be used alone or in combination.

  Examples of the copolymerization monomer include monomers having carboxyl groups such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid, and hydroxyl groups such as 2-hydroxyethyl (meth) acrylate and N-methylol (meth) acrylamide. Monomers, monomers having a functional group such as a monomer containing an epoxy group such as glycidyl (meth) acrylate, vinyl acetate, styrene and the like can be mentioned. Among these copolymer monomers, it is preferable to use a monomer containing a functional group capable of reacting with a crosslinking agent, particularly a monomer having a carboxyl group.

  The ratio of the copolymerization monomer unit (a) in the acrylic polymer is not particularly limited as long as the acrylic polymer has a tackiness that satisfies reworkability and durability. The average molecular weight of the acrylic polymer is not particularly limited, but the weight average molecular weight is preferably about 300,000 to 2.5 million.

  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 compounds can be used, and the reaction temperature is usually about 50 to 85 ° C. and the reaction time is about 1 to 8 hours. Among the above production methods, the solution polymerization method is preferable, and a polar solvent such as ethyl acetate or toluene is generally used as the solvent for the acrylic polymer. The solution concentration is usually about 20 to 80% by weight.

  In addition to containing the acrylic polymer as a base polymer, the pressure-sensitive adhesive can contain a crosslinking agent. Examples of the crosslinking agent include organic crosslinking agents and polyfunctional metal chelates capable of crosslinking with functional groups such as carboxyl groups and hydroxyl groups introduced into the acrylic polymer.

  Examples of the organic crosslinking agent include those having two or more functional groups that react with carboxyl groups, hydroxyl groups, and the like, such as epoxy crosslinking agents, isocyanate crosslinking agents, and imine crosslinking agents. As the organic crosslinking agent, an isocyanate crosslinking agent is preferable.

  As the polyfunctional metal chelate, a polyvalent metal is a covalent bond or coordinate bond with an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. can give. Among these, Al, Zr, and Ti are preferable. Examples of the atom in the organic compound that is covalently or coordinately bonded include an oxygen atom, and the organic compound includes an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, a ketone compound, and the like.

  The blending ratio of the acrylic polymer and the cross-linking agent is not particularly limited. However, when the cross-linking agent is blended, the polyfunctional compound (solid content) is usually 0. The amount is about 01 to 6 parts by weight, preferably about 0.1 to 3 parts by weight.

  Furthermore, the pressure-sensitive adhesive includes various tackifiers, plasticizers, fillers, antioxidants, ultraviolet absorbers, silane coupling agents, etc., as necessary, without departing from the object of the present invention. These additives can also be used as appropriate.

  As the fine particles dispersed in the resin layer forming the adhesive layer, either an organic material or an inorganic material can be used, and those having excellent dispersibility in an acrylic polymer are particularly preferable.

  Examples of the organic fine particles include cross-linked or non-cross-linked products made of various polymers such as polymethyl methacrylate, polyurethane, polystyrene, melamine resin, and silicone, and inorganic fine particles include silica, alumina, calcium oxide, titania, Examples include zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide. The particle size of the fine particles is smaller than the thickness of the pressure-sensitive adhesive layer, and is usually preferably about 1 to 10 μm and preferably has a uniform particle size distribution. The shape of the fine particles is not particularly limited, but a true spherical shape is particularly preferable because it provides a stable adhesive layer surface.

  The amount of fine particles used is preferably as described above. In general, the haze value increases as the content of fine particles increases, but the increase in the haze value can be suppressed by combining the refractive index of the acrylic polymer and the fine particles. Therefore, as the acrylic polymer and fine particles used in the present invention, a combination having a small difference in refractive index is preferable. Further, when porous fine particles are used as the fine particles, it can be expected that the refractive index difference is eliminated because the acrylic polymer is impregnated in the fine particles.

  As shown in FIG. 1, the pressure-sensitive adhesive optical film of the present invention is provided with a pressure-sensitive adhesive layer 2 on an optical film 1. A release sheet 3 can be provided on the adhesive layer 2. The adhesive layer 2 is formed of a resin layer 2a and fine particles 2b.

  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. Examples of the optical film include a polarizing film, an elliptically polarizing film, a polarizing film having an optical compensation function, a polarizing film having a viewing angle expansion function, and a polarizing film having a brightness enhancement function. In these films, a retardation film, an optical compensation film, a brightness enhancement film, an antiglare sheet or the like is laminated on a polarizing film.

  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 side or both sides of the polarizer, a transparent protective layer can be provided as a coating layer 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 alignment polyester liquid crystalline polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded to a spacer portion that imparts 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 examples thereof include a method of applying a pressure-sensitive adhesive composition (solution) containing fine particles to the optical film 1 and drying, a method of transferring with a release sheet 3 provided with the pressure-sensitive adhesive layer 2, and the like. . Although the thickness of the adhesion layer 2 (dry film thickness) is not specifically limited, It is preferable to set it as about 10-40 micrometers.

  In addition, although FIG. 1 illustrates a case where one adhesive layer is provided, a plurality of adhesive layers may be laminated. In that case, the pressure-sensitive adhesive layer 2 containing fine particles is provided in the pressure-sensitive adhesive layer (outermost layer) to be bonded to the liquid crystal cell. The other adhesive layer (intermediate layer) may contain fine particles. Although the thickness of an adhesion layer (intermediate layer) is not specifically limited, It is preferable to set it as about 5-25 micrometers.

  In the case where a plurality of adhesive layers are used, in consideration of the adhesion between the optical film 1 and the adhesive layer 2, it is more preferable that the adhesive layer (intermediate layer) in close contact with the optical film 1 does not contain fine particles. By improving the adhesion between the optical film 1 and the pressure-sensitive adhesive layer 2, it is possible to prevent problems caused by the pressure-sensitive adhesive layer 2 being dropped or protruding.

  In order to improve the adhesion between the adhesive layer 2 (or an intermediate layer when there are multiple adhesive layers) and the optical film 1, the optical film 1 is subjected to corona treatment, UV irradiation, low-pressure UV treatment, plasma irradiation, EB Irradiation and saponification can be performed. Further, a thermosetting or ultraviolet curable resin layer is formed between the adhesive layer 2 and the optical film 1 layer, or an undercoat layer is provided with an isocyanate compound, polyethyleneimine, epoxy compound, silane coupling agent, or the like. You can also.

  Examples of the constituent material of the release sheet 3 include paper, synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate. 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 adhesive layer 2.

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

Example 1
(Preparation of adhesive composition)
In a four-necked flask equipped with a stirring blade, cooling tube, nitrogen inlet tube and thermometer, 94.5 parts of butyl acrylate, 5 parts of acrylic acid, and 0.5 part of 2-hydroxyethyl acrylate are diluted with an ethyl acetate solution. A 50% monomer concentration solution was prepared, and benzoyl peroxide was added to this solution in an amount of 0. After adding 3 parts, nitrogen substitution was performed. Then, reaction was performed at 60 degreeC for 7 hours, stirring, and the acrylic polymer (A) solution was obtained. Trimethylolpropane tolylene diisocyanate was added to 100 parts (solid content) of the acrylic polymer (A) solution by 0. 8 parts γ-glycidylpropane trimethoxysilane 0. An adhesive composition (solution) was prepared by adding 1 part and 10 parts of silica fine particles (Sunsphere H31: average particle size 3 μm, manufactured by Asahi Glass Co., Ltd.).

(Preparation of adhesive optical film)
The pressure-sensitive adhesive composition (solution) produced as described above was applied onto a polyethylene terephthalate separator so that the thickness after drying was 25 μm, and dried to form a fine particle-containing pressure-sensitive adhesive layer. This fine particle-containing pressure-sensitive adhesive layer is transferred to a 180 μm-thick polarizing film (polyvinyl alcohol film impregnated with iodine and stretched, and then a triacetyl cellulose film bonded to both sides via an adhesive) to transfer the pressure-sensitive adhesive film Was made.

Example 2
In Example 1 (Preparation of pressure-sensitive adhesive composition), a pressure-sensitive adhesive composition (solution) was prepared in the same manner as in Example 1 except that the amount of silica fine particles used was 30 parts. In Example 1 (production of an adhesive optical film), the polarizing film was an elliptically polarizing plate (prepared by attaching a polycarbonate retardation film to the polarizing film via an acrylic adhesive layer). A pressure-sensitive adhesive elliptically polarizing film was prepared in the same manner as in Example 1 except that a fine particle-containing pressure-sensitive adhesive layer was formed on the retardation film.

  Example 3 To 100 parts of an acrylic polymer (A) solution (solid content), trimethylolpropane tolylene diisocyanate was added in an amount of 0. 8 parts and γ-glycidylpropane trimethoxysilane 0. One part was added to prepare an adhesive composition (solution). The obtained pressure-sensitive adhesive composition (solution) was applied onto a polyethylene terephthalate separator so that the thickness after drying was 10 μm, and dried to form a pressure-sensitive adhesive layer (for an intermediate layer).

  After this pressure-sensitive adhesive layer (for the intermediate layer) is bonded to a polarizing film having a thickness of 180 μm (polyvinyl alcohol film impregnated with iodine and stretched, and then a triacetyl cellulose film bonded to both sides via an adhesive) Through this pressure-sensitive adhesive layer (for intermediate layer), the fine particle-containing pressure-sensitive adhesive layer prepared in Example 1 was bonded and transferred to produce a pressure-sensitive adhesive polarizing film.

Reference Example 1 A pressure-sensitive adhesive composition (solution) in the same manner as in Example 1 except that silicone fine particles (average particle size 3 μm) were used in Example 1 (preparation of pressure-sensitive adhesive composition) instead of silica fine particles. Was prepared. In Example 1 (production of an adhesive optical film), the polarizing film was an elliptically polarizing plate (prepared by attaching a polycarbonate retardation film to the polarizing film via an acrylic adhesive layer). A pressure-sensitive adhesive elliptically polarizing film was prepared in the same manner as in Example 1 except that a fine particle-containing pressure-sensitive adhesive layer was formed on the retardation film.

Comparative Example 1
A pressure-sensitive adhesive composition (solution) was prepared in the same manner as in Example 1 except that silica fine particles were not used in Example 1 (Preparation of pressure-sensitive adhesive composition). In addition, an adhesive polarizing film was prepared in the same manner as in Example 1 (Preparation of adhesive optical film).

Comparative Example 2
In Example 1 (Preparation of pressure-sensitive adhesive composition), the pressure-sensitive adhesive composition was the same as Example 1 except that silica fine particles were not used and the amount of trimethylolpropane tolylene diisocyanate was 3 parts. A product (solution) was prepared. In addition, an adhesive polarizing film was prepared in the same manner as in Example 1 (Preparation of adhesive optical film).

  The following evaluation was performed about the adhesive polarizing film and adhesive elliptical polarizing film (sample) obtained by the said Example and the comparative example. The evaluation results are shown in Table 1.

(Heating durability)
The sample was cut into a 12-inch size, attached to a glass plate, and autoclaved (50 ° C. × 0.5 MPa × 15 minutes). Then, it was put in an atmosphere of 90 ° C. (dry) for 500 hours, and the occurrence of defects was confirmed according to the following criteria.

○: No failure occurred.
X: Problems such as foaming and peeling are observed.

(Humidification durability)
The sample was cut into a 12-inch size, attached to a glass plate, and autoclaved (50 ° C. × 0.5 MPa × 15 minutes). Then, it was put in an atmosphere of 60 ° C. and 90% RH for 500 hours, and the occurrence of defects was confirmed according to the following criteria.
○: No failure occurred.
X: Problems such as foaming and peeling are observed.

(Adhesion to glass)
The sample was cut to a width of 25 mm, attached to a non-alkali glass plate (manufactured by Corning: Corning 1737), and autoclaved (50 ° C. × 0.5 MPa × 15 minutes). Thereafter, using a tensile tester, the peel response force was measured at a peel rate of 300 m / min at a peel angle of 90 ° and a room temperature atmosphere (25 ° C.) to obtain an adhesive force (N / 25 mm). Reworkability is good when the adhesion to glass is 10 N / 25 mm or less.

(Haze value)
The haze value of the adhesive layer of the sample was measured with a haze meter manufactured by Suga Test Instruments Co., Ltd. according to JIS-K7105. The transparency is good when the haze value is 10% or less. The haze value of the pressure-sensitive adhesive layer is a value obtained by sandwiching the pressure-sensitive adhesive layer with a separator made of polyethylene terephthalate, measuring the haze value of each separator with the pressure-sensitive adhesive layer interposed therebetween, and then removing the haze value of the separator.

表１に示す通り、本発明（実施例）は、耐久性がよく、また対ガラス接着力が１０Ｎ／２５ｍｍ以下でリワーク性もよい。また、透明性も良好である。

As shown in Table 1, the present invention (Examples) has good durability and good reworkability with an adhesion to glass of 10 N / 25 mm or less. Moreover, transparency is also favorable.

DESCRIPTION OF SYMBOLS 1 Optical film 2a Resin layer 2b Fine particle 3 Release sheet

Claims (6)

An adhesive layer for adhering the optical film to the glass substrate of the liquid crystal panel on one surface of the optical film , wherein the adhesive layer is formed of acrylic polymer and fine particles as a main component of the resin layer, The particle diameter of the fine particles is 1 to 10 μm (except for the case of 1 μm), the resin layer is formed of an adhesive containing an acrylic polymer and a silane coupling agent, and the acrylic polymer 100 1 to 50 parts by weight of the fine particles with respect to parts by weight (however, the fine particles exclude 50 parts by weight with respect to 100 parts by weight of the acrylic polymer) ,
The pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer has an adhesion to glass of 10 N / 25 mm or less, and a haze value of the pressure-sensitive adhesive layer is 10% or less.   The acrylic polymer is an acrylic polymer obtained by copolymerizing an alkyl (meth) acrylate and a copolymerization monomer containing a carboxyl group-containing monomer and a hydroxyl group-containing monomer. Adhesive layer.   The pressure-sensitive adhesive layer according to claim 1, wherein the pressure-sensitive adhesive further contains a crosslinking agent. The pressure-sensitive adhesive layer according to any one of claims 1 to 3, wherein the alkyl group of the alkyl (meth) acrylate constituting the main skeleton of the acrylic polymer has an average carbon number of 1 to 12. The fine particles, the adhesive layer according to any one of claims 1-4, characterized in that the fine particles of organic or inorganic material. Adhesive layer according to any one of claims 1 to 5, wherein the optical film is a polarizing film.

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