TW201606015A - Adhesive composition and adhensive film - Google Patents

Abstract

The present invention provides an adhesive composition capable of forming an adhesive layer having excellent reworkability and high adherence performance irrespective of being a thin film, and an adhesive film using the same. More specifically, the present invention relates to an adhesive composition containing: 100 parts by weight in total of (1) meth(acrylate) monomers including at least one selected from the group of monomers consisting of alkyl (meth)acrylate monomers having a C1 to C14 alkyl group and (meth)acrylate monomers having an aromatic group; 0.1 to 3.5 parts by weight with respect to (1) of (2) a hydroxyl group-containing copolymerizable monomer; an acrylic-based polymer, which is a copolymer having an acid value of 0.1 or less and a weight-average molecular weight of 1,000,000 or more; and 0.01 to 0.8 parts by weight with respect to (1) of (3) an isocyanate compound as a crosslinking agent, wherein the adhesive composition includes at least 30 parts by weight or more of butyl acrylate among (1) and does not contain a carboxyl group-containing copolymerizable vinyl monomer.

Description

Adhesive composition and adhesive film

The present invention relates to an adhesive composition and an adhesive film for bonding optical members such as a polarizing plate.

In order to bond an optical member such as a polarizing plate or a retardation film to an adherend such as a liquid crystal cell by an adhesive layer, various adhesive films have been proposed (for example, refer to Patent Documents 1 and 2).

Patent Document 1 describes an optical adhesive composition containing a butyl acrylate or the like as a main component and containing an acrylamide compound or the like.

Patent Document 2 describes an optical adhesive having a (meth) acrylate having an alkyl group having 4 to 8 carbon atoms as a main component monomer and having a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer. combination.

Further, in order to increase the refractive index of the adhesive layer, various adhesive films have been proposed through repeated studies (for example, refer to Patent Documents 3 to 8).

Patent Document 3 describes an optical adhesive composition having an aromatic ring and containing a tackifier having a refractive index of 1.51 to 1.75.

Patent Document 4 describes an adhesive sheet comprising an adhesive composition containing a copolymerizable polymer which is a copolymerizable polymer of an aromatic ring-containing acrylic modified monomer.

Patent Document 5 describes an optical adhesive composition comprising an aromatic ring-containing tackifying resin and an aromatic phosphate plasticizer.

Patent Document 6 describes an adhesive formed by curing an adhesive composition comprising: an acrylic resin; and an aromatic compound containing one ethylenically unsaturated group.

Patent Document 7 describes an optical member in which a retardation film and a birefringent plate are fixed to each other by an acrylic adhesive containing an aromatic monomer.

Patent Document 8 describes an adhesive composition containing a polyurethane resin obtained by reacting an aromatic diisocyanate with an aromatic polyester diol.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2012-177022

Patent Document 2: JP-A-2012-201734

Patent Document 3: Japanese Laid-Open Patent Publication No. 2007-084762

Patent Document 4: Japanese Laid-Open Patent Publication No. 2011-153169

Patent Document 5: Japanese Laid-Open Patent Publication No. 2012-167188

Patent Document 6: Japanese Laid-Open Patent Publication No. 2012-021148

Patent Document 7: Japanese Laid-Open Patent Publication No. 2006-293281

Patent Document 8: JP-A-2009-091522

In recent years, in order to achieve thinning of optical components, as The adhesive film to which the interlayer of the optical member is bonded is required to be a thin adhesive film of the adhesive layer.

Generally, the adhesive force of the adhesive layer is approximately proportional to the thickness of the adhesive layer. Therefore, if the thickness of the adhesive layer is made thinner, the adhesive force is lowered.

However, in recent years, it is required that the adhesive film has the same performance as that of the conventional adhesive film (the adhesive layer is a thick layer having a thickness of about 30 μm ) even if the thickness of the adhesive layer is made thin, and The durability after long-term placement in a high-temperature and high-humidity environment also has the same performance as that of the conventional adhesive film.

In addition, from the viewpoint of being able to reduce the thickness of the pressure-sensitive adhesive layer and forming an adhesive layer that does not require aging treatment (curing at a constant temperature), it is required to form a NCF (Non Carrier Film). It is composed only of an adhesive layer from which the adhesive film substrate has been removed, and has a member of a "release film (release film) / adhesive layer / release film".

Further, in the conventional adhesive film, since the adhesive film is bonded to the adherend, the aging treatment is performed, so that the adhesion between the adherend and the adhesive layer can be improved.

However, in the case of the adhesive film using the NCF form, since the aging treatment of the adhesive layer has been completed, the adhesion between the adherend and the adhesive layer is insufficient. Based on this, there is a problem that it is necessary to perform surface treatment such as corona treatment on the surface of the adherend.

There is therefore a need for an adhesive film that meets these requirements and overcomes these problems.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a film which has excellent reworkability and high quality. An adhesive composition of an adhesive adhesive layer, and an adhesive film using the adhesive composition.

In order to solve the above problems, the pressure-sensitive adhesive composition of the present invention is characterized in that a hydroxyl group-containing copolymer is used as a monomer having a functional group as a functional monomer and a hydroxyl group-containing copolymer is not used. As the copolymer of a copolymerizable vinyl monomer having a weight average molecular weight of 1,000,000 or more, an isocyanate compound as a crosslinking agent is used, and a decane coupling agent is more preferably used in combination.

Further, in order to solve the above problems, the present invention provides an adhesive composition comprising: an acrylic polymer as a copolymer having an acid value of 0.1 or less and a weight average molecular weight of 1,000,000 or more; and (3) Isocyanate compound as a crosslinking agent, The acrylic polymer contains (1) as a (meth) acrylate monomer, an alkyl (meth) acrylate monomer having a C1 to C14 carbon number from an alkyl group, and an aryl group-containing monomer. At least one or more of the monomer groups composed of the (meth) acrylate monomer, and containing at least 30 parts by weight or more of butyl acrylate in a total of 100 parts by weight of the (meth) acrylate monomer, Further, the acrylic polymer does not contain a carboxyl group-containing copolymerizable vinyl monomer, but contains (2) a hydroxyl group-containing copolymer with respect to a total of 100 parts by weight of the (meth) acrylate monomer. 0.1 to 3.5 parts by weight of the vinyl monomer, The content of the (3) isocyanate compound as a crosslinking agent is 0.01 to 0.8 parts by weight based on 100 parts by weight of the total (meth) acrylate monomer.

100 parts by weight of the aforementioned (meth) acrylate single The body preferably further contains 0.01 to 0.5 part by weight of a (4) decane coupling agent.

Further, it is preferred that the isocyanate compound is a trimethylolpropane adduct of toluene diisocyanate.

Further, it is preferred that the (2) hydroxyl group-containing copolymerizable vinyl monomer is selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and (meth)acrylic acid 4. At least one or more of the compound group consisting of -hydroxybutyl ester and 2-hydroxyethyl (meth)acrylate.

Further, the present invention provides an adhesive layer which is an adhesive layer obtained by crosslinking the above-mentioned adhesive composition, and has a gel fraction of 40 to 75% after cross-linking and an adhesive layer having a thickness of 25 μm . The adhesion is 1.5~6.0N/25mm.

Further, it is preferable that the adhesive layer after bonding the adhesive layer to the adherend is at a temperature of from 1.5 to 10 N/25 mm at 70 ° C for 10 days.

Further, the present invention provides an adhesive film in which the above-mentioned adhesive layer is laminated on one surface of a substrate.

Further, the present invention provides an adhesive film for bonding a polarizing plate and a display panel, which uses the above-mentioned adhesive film.

Further, the present invention provides an adhesive layer which is used as an adhesive layer of a polarizing plate with an adhesive layer.

Further, the present invention provides an adhesive layer which is used as an adhesive layer of a polarizing plate with an adhesive layer, and a phase having a phase difference of λ /4 or λ /2 is used as a constituent material of the polarizing plate. Poor film.

Further, the present invention provides an optical film with an adhesive layer in which the aforementioned adhesive layer is laminated on at least one surface of the optical film.

According to the present invention, an adhesive layer having both flexibility, rigidity, durability, and reworkability, and an adhesive film using the adhesive layer can be obtained, and the adhesive layer is characterized by a conventional adhesive. When the amount of the crosslinking agent and the amount of the functional group are reduced, the layer can be an adhesive layer having a high gel fraction after crosslinking.

Although the adhesive film of the present invention is a film, it has excellent reworkability and high adhesiveness.

[Implementation of the Invention]

Hereinafter, the present invention will be described based on preferred embodiments.

The adhesive composition of the present invention comprises: an acrylic polymer as a copolymer having an acid value of 0.1 or less and a weight average molecular weight of 1,000,000 or more; and (3) an isocyanate compound as a crosslinking agent, The acrylic polymer contains (1) as a (meth) acrylate monomer, an alkyl (meth) acrylate monomer having a C1 to C14 carbon number from an alkyl group, and an aryl group-containing monomer. At least one or more of the monomer groups composed of the (meth) acrylate monomer, and containing at least 30 parts by weight or more of butyl acrylate in a total of 100 parts by weight of the (meth) acrylate monomer, Further, the acrylic polymer does not contain a carboxyl group-containing copolymerizable vinyl monomer, but contains (2) a hydroxyl group-containing copolymer with respect to a total of 100 parts by weight of the (meth) acrylate monomer. 0.1 to 3.5 parts by weight of the vinyl monomer, With respect to a total of 100 parts by weight of the (meth) acrylate monomer, The content of the isocyanate compound as the crosslinking agent in (3) is 0.01 to 0.8 parts by weight.

In the adhesive composition of the present invention, as the alkyl (meth) acrylate monomer having an alkyl group having C1 to C14, methyl (meth) acrylate or (meth) acrylate may be mentioned. Ethyl ester, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, amyl (meth) acrylate, (meth) acrylate Hexyl ester, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, (A) Isodecyl acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, (A) At least one of tetradecyl acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, and the like. The alkyl group in the alkyl (meth) acrylate monomer may be any of a linear chain, a branched chain, and a cyclic group.

In a total of 100 parts by weight of the (meth) acrylate monomer, the total content of the alkyl (meth) acrylate monomer having a C1 to C14 alkyl group is preferably 70 parts by weight or more, and may be 100 parts by weight. The proportion of the alkyl (meth) acrylate monomer having an alkyl group having a C1 to C14 alkyl group is preferably 50 to 99.9 parts by weight based on 100 parts by weight of the acrylic polymer (copolymer) of the adhesive composition. In the present invention, butyl acrylate is used as an essential monomer. In a total of 100 parts by weight of the (meth) acrylate monomer, the content of butyl acrylate is preferably at least 30 parts by weight.

Further, in the present invention, the adhesive composition is passed through a total of 100 parts by weight of an alkyl (meth) acrylate having an alkyl group having a C1 to C14 carbon number. The content of the methyl acrylate monomer in the (meth) acrylate monomer having one or more kinds of the ester monomers is 20 parts by weight or more, and the refractive index of the pressure-sensitive adhesive layer can be increased to 1.47 or more.

In the adhesive composition of the present invention, one or more of the aryl group-containing (meth) acrylate monomers may be contained as the (meth) acrylate monomer. Examples of the aryl group-containing (meth) acrylate monomer include benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxy (meth) acrylate. Butyl ester, 2-(1-naphthalenyloxy)ethyl (meth)acrylate, 2-(2-naphthalenyloxy)ethyl (meth)acrylate, 6-(1-naphthyloxy)(meth)acrylate Hexyl ester, 6-(2-naphthyloxy)hexyl (meth)acrylate, 8-(1-naphthalenyloxy)octyl (meth)acrylate, 8-(2-naphthyloxy)(meth)acrylate Base) octyl ester and the like. In order to obtain an adhesive layer having a high refractive index, it is preferred to mix at least one or more aryl group-containing (meth) acrylate monomers.

By mixing these aryl group-containing (meth) acrylate monomers with alkyl (meth) acrylate monomers having an alkyl group having C1 to C14, the resulting adhesive layer can be refracted. The rate is increased and adjusted, the refractive index difference between the optical members is reduced, and total reflection is reduced, whereby the total light transmittance can be improved. In the adhesive layer of the present invention, when the adhesive composition comprises an aryl group-containing (meth) acrylate monomer, it is preferably aryl group-containing in a total of 100 parts by weight of the (meth) acrylate monomer ( The content of the methyl acrylate monomer is 5 to 30 parts by weight.

In addition, by copolymerizing an aryl group-containing (meth) acrylate monomer, the adhesive is added in an amount of 20 parts by weight or more of the methyl acrylate monomer in a total of 100 parts by weight of the (meth) acrylate monomer. Effect of the refractive index of the layer In comparison, the refractive index of the adhesive layer can be further increased.

In addition, as described above, the method of increasing the refractive index of the adhesive layer includes the following two methods: a method of containing 20 parts by weight or more of a methyl acrylate monomer in a total of 100 parts by weight of the (meth) acrylate monomer. And a method of copolymerizing an aryl group-containing (meth) acrylate monomer. Each method may be employed singly, but it is more preferred to use the above two methods in combination.

In the adhesive composition of the present invention, the acrylic polymer as a functional group-containing monomer does not include a carboxyl group-containing copolymerizable vinyl monomer, but includes a hydroxyl group-containing copolymerizable vinyl monomer. As the functional group-containing monomer, only a hydroxyl group-containing copolymerizable vinyl monomer may be used.

Examples of the hydroxyl group-containing copolymerizable vinyl monomer include 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. a hydroxyl group-containing (meth)acrylic acid alkyl ester such as 2-hydroxyethyl (meth)acrylate; N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, At least one or more of hydroxyl group-containing (meth) acrylamides such as N-hydroxyethyl (meth) acrylamide.

Among them, the hydroxyl group-containing copolymerizable vinyl monomer is preferably selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. At least one or more of the compound groups consisting of 2-hydroxyethyl (meth)acrylate.

Further, in the adhesive layer of the present invention, the hydroxyl group-containing copolymerizable vinyl monomer contained in the adhesive composition can be used as a copolymerizable ethylene for reducing the content of a carboxyl group-containing copolymerizable vinyl monomer. The base monomer is used, and the carboxyl group-containing copolymerizable vinyl monomer makes the obtained adhesive layer transparent to conductivity Corrosive influences on corrosive adherends such as the ITO surface of the film. Therefore, the hydroxyl group-containing copolymerizable vinyl monomer can contribute to the improvement of the adhesion of the adhesive layer and the reduction of corrosion. In the adhesive layer of the present invention, the content of the hydroxyl group-containing copolymerizable vinyl monomer in the adhesive composition is preferably 0.1 to 3.5 parts by weight based on 100 parts by weight of the total (meth) acrylate monomer.

The acrylic polymer of the adhesive composition used in the adhesive layer of the present invention is a copolymer having an acid value of 0.1 or less and a weight average molecular weight of 1,000,000 or more, which comprises (1) as a (meth) acrylate single. At least one selected from the group consisting of a (meth)acrylic acid alkyl ester monomer having an alkyl group having from C1 to C14 and an aryl group-containing (meth) acrylate monomer In the above, in a total of 100 parts by weight of the (meth) acrylate monomer, the content of butyl acrylate is at least 30 parts by weight or more. Further, the acrylic polymer does not contain a carboxyl group-containing copolymerizable vinyl monomer, but contains (2) a hydroxyl group-containing copolymer with respect to a total of 100 parts by weight of the (meth) acrylate monomer. The vinyl monomer is 0.1 to 3.5 parts by weight.

The polymerization method of the copolymer is not particularly limited, and a suitable known polymerization method such as a solution polymerization method or an emulsion polymerization method can be used. The acrylic polymer preferably contains 50 to 100% by weight of an acrylic monomer such as a (meth) acrylate monomer or a (meth) acrylamide.

In the above-mentioned adhesive composition, characteristics such as a desired physical property value can be adjusted by blending a crosslinking agent and an appropriate optional additive with the above acrylic polymer.

The (3) crosslinking agent may, for example, be hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate or toluene diisocyanate. a biuret modified or isocyanurate modified product of a diisocyanate such as benzodimethyl diisocyanate, or an adduct of a trivalent or higher polyhydric alcohol such as trimethylolpropane or glycerin At least one or more of the polyisocyanate compounds. The acrylic polymer preferably contains a hydroxyl group as a functional group capable of undergoing a crosslinking reaction with an isocyanate compound of a crosslinking agent, and preferably contains a monomer having such a functional group in a side chain. Further, the adhesive composition preferably contains 0.01 to 0.8 part by weight of an isocyanate compound based on 100 parts by weight of the total (meth) acrylate monomer. As the (3) crosslinking agent, only an isocyanate compound may be used. The isocyanate compound is preferably an adduct of toluene diisocyanate, and particularly preferably a trimethylolpropane adduct of toluene diisocyanate.

Preferably, the above adhesive composition further contains (4) a decane coupling agent. The (4) decane coupling agent may, for example, be a compound having at least one organic functional group and at least one hydrolyzable group in one molecule, and the hydrolyzable group is an alkoxy group bonded to a ruthenium atom. Preferably, the decane coupling agent has at least one organic functional group selected from the group consisting of an epoxy group, a (meth) propylene methoxy group, a fluorenyl group, and an amino group. Here, the (meth) propylene decyloxy group means a propylene fluorenyloxy group (CH ₂ =CHCOO-) or a methacryl oximeoxy group (CH ₂ =C(CH ₃ )COO-).

As the decane coupling agent having an epoxy group, 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldiethoxydecane, and 3-epoxy can be exemplified. Propoxypropylmethyldimethoxydecane, 3-glycidoxypropyltriethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 2-( 3,4-epoxycyclohexyl)ethylmethyldimethoxydecane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxydecane, 2-(3,4-epoxy Cyclohexyl)ethyltriethoxydecane, 5,6-epoxyhexyltrimethoxydecane, 5,6-epoxyhexylmethyldimethoxyindole Alkane, 5,6-epoxyhexylmethyldiethoxydecane, 5,6-epoxyhexyltriethoxydecane, and the like.

As the decane coupling agent having a (meth) propylene fluorenyloxy group, 3-(meth)acryloxypropyltrimethoxydecane, 3-(meth)acryloxypropylpropyl group can be exemplified. Dimethoxy decane, 3-(methyl) propylene methoxy propyl triethoxy decane, 3-(methyl) propylene methoxy propyl methyl diethoxy decane, 3- (methyl And propylene methoxy propyl dimethyl ethoxy decane, 3-(methyl) propylene methoxy propyl dimethyl methoxy decane, and the like.

The decane coupling agent having a mercapto group may, for example, be 3-mercaptopropylmethyldimethoxydecane, 3-mercaptopropyltrimethoxydecane, 3-mercaptopropylmethyldiethoxydecane, or - Mercaptopropyltriethoxydecane, and the like.

The decane coupling agent having an amino group may, for example, be 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, N-phenyl-3-aminopropyltrimethoxydecane, or N. -2-(aminoethyl)-3-aminopropylmethyldimethoxydecane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxydecane, N-2-( Aminoethyl)-3-aminopropyltrimethoxydecane, N-2-(aminoethyl)-3-aminopropyltriethoxydecane, 3-(methylamino)propyltrimethoxynonane, 3-(methylamino)propyltriethoxydecane, and the like.

Further, an alkoxy oligomer (decaneoxy oligomer) containing the above-described organic functional group and having been oligomerized may be used as the decane coupling agent.

The content of the (4) decane coupling agent is preferably 0.01 to 0.5 parts by weight based on 100 parts by weight of the total (meth) acrylate monomer.

As other optional components, an antioxidant, A known additive such as a surfactant, a curing accelerator, a plasticizer, a filler, a crosslinking catalyst, a crosslinking inhibitor, a curing inhibitor, a processing aid, and an anti-aging agent. These may be used alone or in combination of two or more.

The pressure-sensitive adhesive layer of the present invention can be obtained by applying the above-mentioned pressure-sensitive adhesive composition to a substrate or a release film, and then crosslinking the pressure-sensitive adhesive composition. Preferably, the adhesive layer after crosslinking has a gel fraction of 40 to 75%.

In the case of bonding between layers for optical members, etc., a thin adhesive layer is desirable, and it is preferable that the thickness of the above-mentioned adhesive layer is 1 μm to 25 μm , and more preferably 5 μm to 25 μm . Further, in general, the adhesive force of the adhesive layer is approximately proportional to the thickness of the adhesive layer, but it is preferable that the adhesive layer having a thickness of 25 μm has an adhesive force of 1.5 to 6.0 N/25 mm. Further, it is preferable that the adhesive force after bonding the adhesive layer to the adherend at 70 ° C × 10 days is 1.5 to 10 N / 25 mm. As a to-be-adhered body, a glass plate, a resin film, etc., such as a bismuth-free glass, etc. are mentioned.

When the adhesive layer of the present invention is used for interlayer bonding of optical members or the like, in order to reduce light reflection on the interface between the adhesive layer and the optical member, it is desirable that the refractive index difference be as small as possible. Therefore, the refractive index of the above adhesive layer is preferably 1.47 to 1.50.

The adhesive film of the present invention can be produced by forming the adhesive layer of the present invention on one side of a substrate or a release film.

A resin film such as a polyester film or the like can be used as the release film (separator) for forming the base film of the pressure-sensitive adhesive layer or the protective adhesive surface.

In the base film, the surface of the resin film opposite to the side on which the adhesive layer is formed can be prevented by a release agent, a coating agent, cerium oxide particles or the like of an anthrone or a fluorine-based release agent. Stain treatment, can be applied by antistatic agent coating or mixing, etc. Antistatic treatment carried out.

In the release film, a release treatment by an anthrone or a fluorine-based release agent is performed on the surface on the side where the adhesive surface of the adhesive layer is bonded.

The "release film/adhesive layer/release film" can be formed by bonding the surface of the release film to the mold release film on both surfaces of one of the pressure-sensitive adhesive layers. In this case, the release film on both sides can be peeled off sequentially or simultaneously to expose the adhesive surface, and can be bonded to an optical member such as an optical film. Examples of the optical film include a polarizing film, a retardation film, an antireflection film, an anti-glare film, an ultraviolet absorbing film, an infrared absorbing film, an optical compensation film, and a brightness enhancement film.

The adhesive film of the present invention can be used for bonding various optical films, various optical films for touch panels, various optical films for electronic paper, various optical films for organic EL, and the like to peripheral members of a liquid crystal display mainly composed of a polarizing plate.

Further, the above-mentioned adhesive layer may be laminated on at least one surface of these optical films to produce an optical film with an adhesive layer. Specifically, “optical film/adhesive layer/optical film”, “optical film/adhesive layer/release film”, “optical film/adhesive layer”, “optical film/adhesive layer/optical film” /Adhesive layer / optical film", "optical film / adhesive layer / optical film / adhesive layer / release film", "release film / adhesive layer / optical film / adhesive layer / release film", etc. Composition.

For example, in the case of an "optical film/adhesive layer/release film", in the case of having an adhesive layer protected by a release film, the release film is peeled off to expose an "optical film/adhesive layer". The adhesive layer is bonded to other optical films to obtain a structure in which an adhesive layer is used for interlayer bonding such as "optical film/adhesive layer/optical film".

The adhesive film of the present invention can be preferably used in the bonding of a polarizing plate and a display panel. For example, it is used as an adhesive layer of a polarizing plate with an adhesive layer. As a constituent material of the polarizing plate, a retardation film having a phase difference of λ /4 or λ /2 can be used.

[Examples]

Hereinafter, the present invention will be specifically described based on examples.

<Manufacture of acrylic polymer>

[Example 1]

Nitrogen gas was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction tube, thereby replacing the air in the reaction apparatus with nitrogen. Then, 100 parts by weight of butyl acrylate, 0.2 parts by weight of 8-hydroxyoctyl acrylate were added to the reaction apparatus, and 60 parts by weight of a solvent (ethyl acetate) was simultaneously added. Then, 0.1 part by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise thereto over 2 hours, and the mixture was reacted at 65 ° C for 6 hours to obtain a weight average molecular weight of 1,000,000 or more, which was used in Example 1. Acrylic polymer solution 1. A part of the acrylic polymer was used as an acid value measurement sample to be described later.

[Examples 2 to 5 and Comparative Examples 1 to 3]

Except that the composition of each monomer was adjusted as described in the group (1) and the group (2) in Table 1, the operation was carried out in the same manner as in the above-described acrylic polymer solution 1 used in Example 1, and it was obtained. The acrylic polymer solutions in Examples 2 to 5 and Comparative Examples 1 to 3. In addition, the measurement results were not particularly shown, but the acrylic polymer contained in the acrylic polymer solutions of Examples 2 to 5 and Comparative Examples 1 to 3 had a weight average molecular weight of 1,000,000 or more.

<Manufacture of Adhesive Composition, Adhesive Layer and Adhesive Film>

[Example 1]

In the acrylic polymer solution 1 of Example 1 produced as described above, 0.2 part by weight of Coronate L was added ( L) (trimethylolpropane (TMP) adduct of toluene diisocyanate (TDI) compound), 0.05 part by weight of KBM-403 (3-glycidoxypropyltrimethoxydecane) and stirred and mixed The adhesive composition of Example 1 was obtained. The adhesive composition is applied onto a release film composed of a polyethylene terephthalate (PET) film coated with an fluorenone resin, and then dried at a temperature of 90 ° C to remove the solvent, and then After aging for 7 days in an environment of 23 ° C and 50% RH, Example 1 of the adhesive layer having a thickness of 25 μm obtained by crosslinking the adhesive composition on one side of the release film was obtained. Adhesive film.

[Examples 2 to 5 and Comparative Examples 1 to 3]

Except that the composition of the additive was adjusted as described in the groups (3) and (4) of Table 1, the operation was carried out in the same manner as in the above-described adhesive film of Example 1, and Examples 2 to 5 and Comparative Example 1 were obtained. 3 adhesive film.

In Table 1, the numerical value in parentheses indicates the value of the weight of the group (2) to (4) obtained by setting the total weight of the group (1) to 100 parts by weight, as the group (2) to (4). ) The addition ratio of the group.

Further, the compound names corresponding to the abbreviations of the respective components used in Table 1 are shown in Table 2. In addition, Coronate ( L is a trade name of Nippon Polyurethane Industry Co., Ltd., D-110N is a trade name of Mitsui Chemicals Co., Ltd., and KBM-403 and KBM-803 are Shin-Etsu Chemical Co., Ltd. Product name. TDI refers to toluene diisocyanate, TMP refers to trimethylolpropane, and XDI refers to benzenedimethyl diisocyanate. In Tables 1 and 2, the carboxyl group-containing copolymerizable vinyl monomer was recorded in the group (2) together with the hydroxyl group-containing copolymerizable vinyl monomer.

<Test method and evaluation>

The release film (PET film coated with an oxime resin) was peeled off from the adhesive films of Examples 1 to 5 and Comparative Examples 1 to 3 to expose the adhesive layer, and the adhesive layer was transferred to a single sheet of a polarizing plate (film). On the surface.

<Method for measuring adhesion>

The adhesive layer having a thickness of 25 μm was transferred to one side of a polarizing plate (film) having a thickness of 180 μm to obtain an adhesive film (an optical film with an adhesive layer) as a sample.

The obtained adhesive film was bonded to a non-tin surface of an antimony glass washed with acetone by a pressure roller, and subjected to autoclave treatment at 50 ° C, 0.5 MPa × 20 minutes, and then returned to 23 ° C × 50 In the environment of %RH, it took 1 hour. The peeling strength of the adhesive film after this was measured by the tensile tester in accordance with JIS Z0237 "Adhesive tape and adhesive sheet test method", and the peeling strength at the time of peeling at 180 mm/min in the 180° direction was used as the adhesive film. Adhesion of the adhesive layer (N/25mm).

<Method for measuring acid value>

The acid value of the acrylic polymer was determined as follows: The sample was dissolved in a solvent (a solvent in which diethyl ether and ethanol were mixed at a volume ratio of 2:1), and an electric potential difference automatic titrator (AT-610, Kyoto) was used. The company made a potentiometric titration with a potassium hydroxide ethanol solution having a concentration of about 0.1 mol/L, and measured the amount of the potassium hydroxide ethanol solution required for neutralizing the sample. Then, the acid value was determined according to the following formula.

Acid value = (B × f × 5.611) / S

B = amount of 0.1 mol/L potassium hydroxide ethanol solution used in the titration (mL)

f=0.1mol/L coefficient of potassium hydroxide ethanol solution (factor)

S = quality of the solid component of the sample (g)

<Method for measuring gel fraction>

The quality of the measurement sample after the aging was completed and before the polarizing plate was attached was accurately measured, and after immersing in toluene for 24 hours, it was filtered through a 200 mesh wire mesh. Then, after drying the filtrate at 100 ° C for 1 hour, the quality of the residue was accurately measured, and the gel fraction of the adhesive layer (adhesive after crosslinking) was calculated according to the following formula.

Gel fraction (%) = insoluble portion quality (g) / adhesive quality (g) × 100

<Test method for durability>

A 10 cm square adhesive film prepared in the same manner as in the measurement of the adhesive force was applied to the non-tin surface of the flawless glass in the same manner to prepare a sample, and the sample was placed in a predetermined environment (80 ° C). After 250 hours in a dry environment or an environment of 60 ° C × 90% RH, the mixture was taken out to an environment of 23 ° C × 50% RH, and the state of the adhesive film after 1 hour was visually observed to determine the durability.

○: The adhesive film did not cause peeling and foaming at all.

△: Part of the adhesive film was peeled off and foamed.

×: Peeling and foaming occurred in the entire adhesive film.

<Test method for reworkability>

A 10 cm square adhesive film prepared in the same manner as in the measurement of the adhesive force was applied to the non-tin surface of the flawless glass in the same manner to prepare a sample, and the sample was placed in an environment of 70 ° C. After the day, the pressure was measured in an environment of 23 ° C, and the adhesion of the adhesive film after standing for 1 hour was measured to determine the reworkability.

○: The adhesion after 70 ° C × 10 days was 1.5 to 10 N / 25 mm.

△: The adhesion after 70 ° C × 10 days is greater than 10 N / 25 mm but below 20 N / 25 mm.

×: The adhesion after 70 ° C × 10 days is greater than 20 N / 25 mm (can not be peeled off).

The evaluation results are shown in Table 3. With respect to the acid value, it was confirmed that the acrylic polymers of Examples 1 to 5 and Comparative Examples 2 and 3 which do not have a carboxyl group-containing copolymerizable vinyl monomer have an acid value of 0.1 or less and have a carboxyl group-containing copolymerization property. The acrylic polymer of Comparative Example 1 of the vinyl monomer had an acid value of more than 0.1.

In the adhesive films of Examples 1 to 5, the adhesive force of the adhesive layer having a thickness of 25 μm was in the range of 1.5 to 6.0 N/25 mm, and the gel fraction of the adhesive layer after crosslinking was 40 to 75%. It is also excellent in adhesion and durability. In addition, since the adhesive force after 70 ° C × 10 days after bonding to the adherend is in the range of 1.5 to 10 N / 25 mm, the reworkability is also excellent. That is, the adhesive films of Examples 1 to 5 can satisfy the required requirements and can overcome the problems existing in the prior art.

The adhesive film of Comparative Example 1 may be because the (meth) acrylate monomer does not contain butyl acrylate, and has a carboxyl group-containing copolymerizable vinyl monomer as a functional group-containing monomer, and has a high gel fraction. For this reason, the adhesive layer having a thickness of 25 μm has a strong adhesive force and is inferior in durability and reworkability in an environment of 60 ° C × 90% RH.

The adhesive film of Comparative Example 2 may have poor gelation ratio due to excessive amount of a hydroxyl group-containing copolymerizable vinyl monomer in the adhesive composition, and poor durability in a 60 ° C × 90% RH environment. The durability and reworkability in a dry environment at 80 ° C are also slightly inferior.

In the adhesive film of Comparative Example 3, since the adhesive composition has neither a carboxyl group-containing copolymerizable vinyl monomer nor a hydroxyl group-containing copolymerizable vinyl monomer, the acrylic polymer does not crosslink. The adhesion of the adhesive layer with a gel fraction of 0 and a thickness of 25 μm is very strong. As a result, durability and reworkability are inferior.

As described above, the adhesive films of Comparative Examples 1 to 3 could not satisfy the conventionally proposed requirements and overcome the problems existing in the past.

Claims (11)

An adhesive composition comprising: an acrylic polymer having a copolymer having an acid value of 0.1 or less and a weight average molecular weight of 1,000,000 or more; and (3) an isocyanate compound as a crosslinking agent, wherein the acrylic polymer contains (1) A (meth) acrylate monomer which is selected from a C1 to C14 carbon atom of an alkyl group and an aryl group-containing (meth) acrylate monomer as a (meth) acrylate monomer At least one or more of the monomer groups composed of the body, and containing at least 30 parts by weight or more of butyl acrylate in a total of 100 parts by weight of the (meth) acrylate monomer, and further, the acrylic polymer It does not contain a carboxyl group-containing copolymerizable vinyl monomer, but contains (2) a hydroxyl group-containing copolymerizable vinyl monomer 0.1 to 3.5 with respect to a total of 100 parts by weight of the (meth) acrylate monomer. The content of the (3) isocyanate compound as a crosslinking agent is 0.01 to 0.8 parts by weight based on 100 parts by weight of the total (meth) acrylate monomer. The adhesive composition according to claim 1, wherein the (4) decane coupling agent is further contained in an amount of 0.01 to 0.5 part by weight based on 100 parts by weight of the total (meth) acrylate monomer. . The adhesive composition according to claim 1 or 2, wherein the isocyanate compound is a trimethylolpropane adduct of toluene diisocyanate. The adhesive composition according to any one of claims 1 to 3, wherein the (2) hydroxyl group-containing copolymerizable vinyl monomer is selected from the group consisting of At least one of a group consisting of 8-hydroxyoctyl acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate the above. An adhesive layer which is obtained by crosslinking the adhesive composition according to any one of claims 1 to 4, and has a gel fraction of 40 to 75% after crosslinking. The adhesive layer having a thickness of 25 μm has an adhesive force of 1.5 to 6.0 N/25 mm. The adhesive layer according to claim 5, wherein the adhesive force after the adhesive layer is attached to the adherend at 70 ° C for 10 days is 1.5 to 10 N / 25 mm. An adhesive film in which an adhesive layer according to claim 5 or 6 is laminated on one surface of a substrate. An adhesive film for bonding a polarizing plate and a display panel, which uses the adhesive film described in claim 7 of the patent application. The adhesive layer according to claim 5 or 6, which is used as an adhesive layer of a polarizing plate with an adhesive layer. An adhesive layer as described in claim 5 or 6, which is used as an adhesive layer of a polarizing plate with an adhesive layer, and which has a λ/4 or λ/ as a constituent material of the polarizing plate. A retardation film of phase difference of 2. An optical film with an adhesive layer laminated on at least one side of the optical film with the adhesive layer of claim 5 or 6.