CN103865409B - Adhesive layer and adhesive film - Google Patents

Abstract

The present invention provides an adhesive layer having a high adhesive force and high adhesion despite being a thin film having a thickness of 1 μm to 20 μm, and an adhesive film using the adhesive layer. The adhesive layer is formed by cross-linking an adhesive composition containing an acrylic polymer, wherein the (meth)acrylate monomer containing an alkyl group as a main component of the adhesive composition At least one or more of (meth)acrylate monomers with C1 to C14 atoms and at least one or more of aryl group-containing (meth)acrylate monomers, and as other copolymerizable monomers The body contains at least one or more of nitrogen-containing vinyl monomers, at least one or more of carboxyl-containing copolymerizable vinyl monomers and/or hydroxyl-containing copolymerizable vinyl monomers, and the The thickness of the adhesive layer is 1 μm to 20 μm, and the adhesive force at a thickness of 5 μm is 4.0 (N/25 mm) or more.

Description

Adhesive layer and adhesive film

technical field

The present invention relates to an adhesive layer used for interlayer lamination of optical components and an adhesive film using the adhesive layer. Although the adhesive layer is a thin film with a thickness of 1 μm to 20 μm, it has High cohesion and high adhesion.

Background technique

Various adhesive films have been proposed for bonding optical components such as polarizing plates and retardation plates to adherends such as liquid crystal cells through adhesive layers (for example, refer to Patent Documents 1 and 2).

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

Patent Document 2 describes an optical fiber that uses a (meth)acrylate having an alkyl group with 4 to 8 carbon atoms as a main component monomer, and contains a carboxyl group-containing monomer and a nitrogen-containing vinyl monomer. with adhesive composition.

In addition, 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 which has an aromatic ring and contains a thickener having a refractive index of 1.51 to 1.75.

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

Patent Document 5 describes an optical adhesive composition containing a tackifier resin having an aromatic ring and an aromatic phosphate-based plasticizer.

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

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

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

In recent years, in order to reduce the thickness of optical components, adhesive films used for interlayer lamination of optical components are required to have an adhesive layer with a thickness of 20 μm or less.

In general, the adhesive force of the adhesive layer is approximately proportional to the thickness of the adhesive layer. Therefore, when the thickness of the adhesive layer is reduced, the adhesive force decreases accordingly.

However, in recent years, adhesive films are required to have the same adhesive force as conventional adhesive films (the adhesive layer is a thick layer with a thickness of about 30 μm) even if the thickness of the adhesive layer is reduced. , and the durability after being left for a long time in a high-temperature and high-humidity environment is equal to or better than that of conventional adhesive films.

In addition, from the viewpoint of being able to reduce the thickness of the adhesive layer and form an adhesive layer that does not require an aging treatment (curing at a constant temperature), it is required to form an NCF (Non Carrier Film, non-carrier film) The embodiment has a member constitution of "release film/adhesive layer/release film" including the adhesive layer from which the base material of the adhesive film is removed.

In addition, in the conventional adhesive film, since the adhesive film is bonded to the adherend and then the aging treatment is performed, the adhesion between the adherend and the adhesive layer can be improved.

However, the adhesive film in the form of NCF has already completed the aging treatment of the adhesive layer, so the adhesion between the adherend and the adhesive layer is insufficient. For this reason, there is a problem that surface treatment such as corona treatment needs to be performed on the surface of the adherend.

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

[Prior Art Literature]

【Patent Literature】

[Patent Document 1] Japanese Patent Laid-Open No. 2012-177022

[Patent Document 2] Japanese Patent Laid-Open No. 2012-201734

[Patent Document 3] Japanese Patent Laid-Open No. 2007-084762

[Patent Document 4] Japanese Patent Laid-Open No. 2011-153169

[Patent Document 5] Japanese Patent Laid-Open No. 2012-167188

[Patent Document 6] Japanese Patent Laid-Open No. 2012-021148

[Patent Document 7] Japanese Patent Laid-Open No. 2006-293281

[Patent Document 8] Japanese Patent Laid-Open No. 2009-091522

Contents of the invention

The problem to be solved by the invention

The present invention has been accomplished in view of the above, and its object is to provide an adhesive layer having a high adhesive force and high adhesion and an adhesive layer using the adhesive although it is a film having a thickness of 1 μm to 20 μm. layer of adhesive film.

The method used to solve the problem

In order to solve the above-mentioned problems, the present invention adopts the following as a technical idea: In an adhesive layer obtained by crosslinking an adhesive composition including an acrylic polymer, an alkyl group having C1 to C14 carbon atoms (a base) at least one of the alkyl acrylate monomers as the main component monomer, and at least one of the nitrogen-containing vinyl monomers that can be copolymerized as other copolymerizable monomers, through copolymerization and crosslinking Forms an adhesive layer with tough cohesion and high adhesion.

Furthermore, in order to solve the above-mentioned problems, the present invention provides an adhesive layer obtained by crosslinking an adhesive composition including an acrylic polymer, wherein the adhesive composition is a main component of ( The meth)acrylate monomer contains at least one of the alkyl (meth)acrylate monomers with alkyl carbon atoms of C1-C14 and at least one of the (meth)acrylate monomers containing aryl groups One or more, and at least one or more of nitrogen-containing vinyl monomers, carboxyl-containing copolymerizable vinyl monomers and/or hydroxyl-containing copolymerizable vinyl monomers as other copolymerizable monomers In addition, the adhesive layer has a thickness of 1 μm to 20 μm, and an adhesive force of 4.0 (N/25 mm) or more when the thickness is 5 μm.

In addition, it is preferred that the binder composition comprises:

Relative to 70-95 parts by weight of (A) at least one of (meth)acrylic acid alkyl ester monomers containing 70-95 parts by weight of (A) alkyl carbon atoms having C1-C14 and 5-30 parts by weight of (B) aromatic 100 parts by weight of at least one (meth)acrylate monomer as the main component of (meth)acrylate monomers containing 5 to 50 parts by weight of (C) nitrogen-containing vinyl monomer The weight average molecular weight of at least one or more of the (D) carboxyl group-containing copolymerizable vinyl monomers and/or hydroxyl group-containing copolymerizable vinyl monomers of 0.1 to 5 parts by weight is 20 10,000 to 2 million copolymers; and

0.01-5 parts by weight of (E) crosslinking agent.

In addition, in the adhesive composition, the content of one or more carboxyl group-containing copolymerizable vinyl monomers is preferably contained with respect to 100 parts by weight of the (meth)acrylate monomer as the main component. 2.0 parts by weight or less and/or the content of one or more types of hydroxyl group-containing copolymerizable vinyl monomers is 5.0 parts by weight or less.

In addition, the refractive index of the adhesive layer is preferably 1.47 to 1.50.

Moreover, this invention provides the adhesive film which has the structure of a release film/adhesive layer/release film in which the said adhesive layer was formed on one surface of a release film.

Moreover, this invention provides the adhesive film which laminated|stacked the said adhesive layer on one surface of a base material.

Moreover, this invention provides the film for polarizing plate peripheral parts using the said adhesive film.

Moreover, this invention provides the film for touch panels which used the said adhesive film.

Moreover, this invention provides the film for electronic papers which used the said adhesive film.

Moreover, this invention provides the film for organic EL (Electro-Luminescence) using the said adhesive film.

Moreover, this invention provides the optical film with an adhesive layer which laminated|stacked the said adhesive layer on at least one surface of an optical film.

Invention effect

According to the present invention, the requirements in the prior art can be met and the problems in the prior art can be overcome, and a kind of adhesive layer with high cohesive force and high adhesion can be provided although it is a thin film with a thickness of 1 μm to 20 μm, and it can be used The adhesive film of the adhesive layer.

detailed description

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

The adhesive layer of the present invention is formed by cross-linking an adhesive composition including an acrylic polymer, wherein the (meth)acrylate monomer containing an alkyl carbon as a main component of the adhesive composition At least one or more of (meth)acrylate monomers with C1 to C14 atoms and at least one or more of aryl group-containing (meth)acrylate monomers, and as other copolymerizable monomers The body contains at least one or more of nitrogen-containing vinyl monomers, at least one or more of carboxyl-containing copolymerizable vinyl monomers and/or hydroxyl-containing copolymerizable vinyl monomers, and the The thickness of the adhesive layer is 1 μm to 20 μm, and the adhesive force at a thickness of 5 μm is 4.0 (N/25 mm) or more.

Examples of alkyl (meth)acrylate monomers having alkyl carbon atoms of C1 to C14 include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, Isopropyl methacrylate, Butyl (meth)acrylate, Isobutyl (meth)acrylate, Pentyl (meth)acrylate, Hexyl (meth)acrylate, Heptyl (meth)acrylate, ( Octyl (meth)acrylate, Isooctyl (meth)acrylate, 2-Ethylhexyl (meth)acrylate, Nonyl (meth)acrylate, Isononyl (meth)acrylate, Acrylic acid (meth) Decyl ester, Undecyl (meth)acrylate, Lauryl (meth)acrylate, Tridecyl (meth)acrylate, Myristyl (meth)acrylate, (Meth) ) at least one of cyclopentyl acrylate, cyclohexyl (meth)acrylate, and the like. The alkyl group in the alkyl (meth)acrylate monomer may be any of linear, branched and cyclic. The ratio of the (meth)acrylate monomer having C1 to C14 alkyl carbon atoms is preferably 50 to 95 parts by weight relative to 100 parts by weight of the acrylic polymer (copolymer) of the pressure-sensitive adhesive composition.

Examples of aryl group-containing (meth)acrylate monomers include benzyl (meth)acrylate, naphthyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxy (meth)acrylate Butyl ester, 2-(1-naphthyloxy)ethyl (meth)acrylate, 2-(2-naphthyloxy)ethyl (meth)acrylate, 6-(1-naphthyloxy)(meth)acrylate ) hexyl ester, (meth)acrylate 6-(2-naphthyloxy)hexyl ester, (meth)acrylate 8-(1-naphthyloxy)octyl ester, (meth)acrylate 8-(2-naphthyloxy) base) octyl ester, etc. In order to obtain an adhesive layer with a high refractive index, it is preferable to mix at least one or more aromatic group-containing (meth)acrylate monomers.

By mixing these aryl group-containing (meth)acrylate monomers with the main component monomers, that is, alkyl (meth)acrylate monomers with alkyl carbon atoms of C1 to C14, the obtained The refractive index of the adhesive layer is adjusted to increase, the refractive index difference between the optical components is reduced, and the total reflection is reduced, thereby improving the total light transmittance. In the adhesive layer of the present invention, when the adhesive composition contains an aryl group-containing (meth)acrylate monomer, its content is 100% relative to the (meth)acrylate monomer as the main component. The weight part is preferably 5 to 30 weight parts.

Examples of nitrogen-containing vinyl monomers include cyclic nitrogen vinyl compounds such as N-vinylpyrrolidone, N-vinylcaprolactam, and (meth)acryloylmorpholine; N-ethyl-N-methyl (Meth)acrylamide, N-methyl-N-propyl (meth)acrylamide, N-methyl-N-isopropyl (meth)acrylamide, N,N-dimethyl (methyl) ) acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N -Dialkyl-substituted (meth)acrylamides such as dibutyl (meth)acrylamide; N-ethyl-N-methylaminoethyl (meth)acrylate, N-methyl-(meth)acrylate N-propylaminoethyl ester, N-methyl-N-isopropylaminoethyl (meth)acrylate, N,N-dimethylaminomethyl (meth)acrylate, N, (meth)acrylate N-dimethylaminoethyl ester, (meth)acrylate N,N-dimethylaminopropyl ester, (meth)acrylate N,N-dimethylaminobutyl ester, (meth)acrylate N,N- Dipropylaminoethyl (meth)acrylate, N,N-dibutylaminoethyl (meth)acrylate and other dialkylaminoethyl (meth)acrylates; N-ethyl-N-methylaminopropyl (methyl) Acrylamide, N-methyl-N-propylaminopropyl (meth)acrylamide, N-methyl-N-isopropylaminopropyl (meth)acrylamide, N,N-dimethylammonia Propyl (meth)acrylamide, N,N-diethylaminopropyl (meth)acrylamide, N,N-dipropylaminopropyl (meth)acrylamide, N,N-dimethyl At least one of dialkyl-substituted aminoalkyl (meth)acrylamides such as aminoethyl(meth)acrylamide, N,N-diethylaminoethyl(meth)acrylamide, and the like.

The nitrogen-containing vinyl monomer preferably does not contain a hydroxyl group, and more preferably does not contain a hydroxyl group or a carboxyl group, so that it can be distinguished from the compound of (D) described later. As such monomers, the monomers exemplified above are preferred, for example, acrylic monomers containing N,N-dialkyl-substituted amino groups or N,N-dialkyl-substituted amide groups; N-vinylpyrrolidone, N- N-vinyl substituted lactams such as vinyl caprolactam; N-(meth)acryloyl substituted cyclic amines such as N-(meth)acryloyl morpholine.

In addition, in the adhesive layer of the present invention, the nitrogen-containing vinyl monomer contained in the adhesive composition can impart necessary adhesive force and durability to the adhesive layer. In the adhesive layer of the present invention, the content of the nitrogen-containing vinyl monomer contained in the adhesive composition is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the (meth)acrylate monomer as the main component.

In addition, in the adhesive layer of the present invention, it is particularly preferable to use N-vinylpyrrolidone, N,N-dimethyl (meth)acrylamide as the nitrogen-containing vinyl monomer contained in the adhesive composition. , N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-dibutyl N,N-dimethylaminopropyl (meth)acrylamide, N,N-diethylaminopropyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide Ethyl(meth)acrylamide, N-vinylcaprolactam, etc.

Examples of carboxyl group-containing copolymerizable vinyl monomers (carboxyl group-containing monomers) include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-( Meth)acryloyloxyethylhexahydrophthalate, 2-(meth)acryloyloxypropylhexahydrophthalate, 2-(meth)acryloyloxyethylhexahydrophthalate Formic acid, 2-(meth)acryloyloxyethylsuccinic acid, 2-(meth)acryloyloxyethylmaleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-( At least one or more of meth)acryloyloxyethyl tetrahydrophthalic acid and the like.

In addition, in the adhesive layer of the present invention, the carboxyl group-containing monomer contained in the adhesive composition can impart necessary cohesion to the adhesive layer. In the adhesive layer of the present invention, the content of the carboxyl group-containing monomer contained in the adhesive composition is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the (meth)acrylate monomer as the main component.

Examples of hydroxyl-containing copolymerizable vinyl monomers (hydroxyl-containing monomers) include 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, (meth)acrylic acid 4-hydroxybutyl ester, hydroxyethyl (meth)acrylate and other hydroxyalkyl (meth)acrylates, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N- At least one or more of hydroxyl group-containing (meth)acrylamides such as hydroxyethyl (meth)acrylamide.

In addition, in the adhesive layer of the present invention, the hydroxyl group-containing monomer contained in the adhesive composition is used as a copolymerizable monomer for reducing the content of the carboxyl group-containing monomer. The monomer affects the corrosiveness of the obtained adhesive layer to the adherend which is easily corroded, such as the ITO surface of the transparent conductive film. Therefore, the hydroxyl group-containing monomer can help to improve the cohesion of the adhesive layer and help to reduce corrosion. In the adhesive layer of this invention, it is preferable that content of the hydroxyl group containing monomer contained in an adhesive composition is 0.1-5 weight part with respect to 100 weight part of (meth)acrylate monomers of a main component.

The copolymer of the adhesive composition used for the adhesive layer of the present invention preferably contains 5 to 50 parts by weight of (C) based on 100 parts by weight of the (meth)acrylate monomer as the main component One or more nitrogen-containing vinyl monomers and 0.1 to 5 parts by weight of (D) at least one carboxyl-containing copolymerizable vinyl monomer and/or hydroxyl-containing copolymerizable vinyl monomer Above, the (meth)acrylate monomer as the main component contains 70 to 95 parts by weight of (A) at least one of (meth)acrylate alkyl monomers with alkyl carbon atoms of C1 to C14 5-30 parts by weight of (B) at least 1 or more types of aryl group-containing (meth)acrylate monomers.

In addition, it is preferable to contain not more than 2.0 parts by weight of one or more carboxyl group-containing copolymerizable vinyl monomers and/or one or more kinds of hydroxyl group-containing copolymerizable vinyl monomers based on 100 parts by weight of (meth)acrylate monomers as main components The copolymerizable vinyl monomer is 5.0 parts by weight or less.

The polymerization method of the copolymer is not particularly limited, and an appropriate known polymerization method such as a solution polymerization method or an emulsion polymerization method can be used. The weight average molecular weight of the copolymer is preferably 200,000 to 2 million.

The above-mentioned copolymer is preferably an acrylic polymer, and preferably contains 50 to 100% by weight of an acrylic monomer such as a (meth)acrylate monomer or (meth)acrylic acid or (meth)acrylamide.

In the above-mentioned adhesive composition, characteristics such as desired physical properties can be adjusted by blending a crosslinking agent and appropriate optional additives into the above-mentioned copolymer.

Examples of the crosslinking agent include biuret-modified products of diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, toluene diisocyanate, and xylylene diisocyanate. or isocyanurate modified products; polyisocyanate compounds such as adducts with trimethylolpropane or glycerin and other polyhydric alcohols with a valence of more than three; metal chelate compounds; epoxy compounds, etc. above. In addition, the binder may be crosslinked by photocrosslinking such as ultraviolet rays.

In the case of using a cross-linking agent to cross-link the copolymer, it is preferable that the copolymer has a functional group capable of cross-linking reaction with the cross-linking agent (according to the type of cross-linking agent, a hydroxyl group or a carboxyl group, etc. can be selected), and it is preferable to contain chain monomers with these functional groups. Moreover, it is preferable that the adhesive composition contains 0.01-5 weight part of (E) crosslinking agents. In addition, the basis of parts by weight is the same as that of (A) to (D) in the above-mentioned copolymer.

As other arbitrary components, silane coupling agents, antioxidants, surfactants, curing accelerators, plasticizers, fillers, crosslinking catalysts, crosslinking inhibitors, curing inhibitors, processing aids, Known additives such as aging agents. These additives may be used alone or in combination of two or more.

The adhesive layer of the present invention can be obtained by crosslinking the adhesive composition after coating the above-mentioned adhesive composition on a substrate or a release film.

It is desirable that the adhesive layer used for interlayer bonding of optical components is a thin adhesive layer, and the thickness of the adhesive layer is preferably 1 μm to 20 μm. In addition, the adhesive force of the adhesive layer is generally proportional to the thickness of the adhesive layer, but the adhesive force at a thickness of 5 μm is preferably 4.0 (N/25 mm) or more. In addition, when the thickness of the adhesive layer is not 5 μm, the "adhesive force at a thickness of 5 μm" (N/25mm) is expressed as T (μm) for the thickness of the adhesive layer and T (μm) for the adhesive layer The cohesive force is recorded as F (N/25mm), and it is calculated by the formula "(cohesive force at a thickness of 5 μm) = 5F/T".

When the adhesive layer of the present invention is used for interlayer bonding of optical components, etc., it is desirable that the difference in refractive index be as small as possible in order to reduce reflection of light at the interface between the adhesive layer and the optical component. Therefore, it is preferable that the refractive index of the said adhesive layer is 1.47-1.50.

The adhesive film of this invention can be manufactured by forming the adhesive layer of this invention on one surface of a base material or a release film.

A resin film such as a polyester film or the like can be used as a base film for forming an adhesive layer or a release film (separator) for protecting an adhesive surface.

As for the base film, on the surface of the resin film opposite to the side where the adhesive layer is formed, a silicone-based, fluorine-based mold release agent or coating agent, silica particles, etc. can be applied. For the antifouling treatment, antistatic treatment by coating or mixing an antistatic agent can be performed.

The release film is subjected to a mold release treatment with a silicone-based or fluorine-based mold release agent or the like on the side of the adhesive layer that is bonded to the adhesive layer.

A configuration of "release film/adhesive layer/release film" can be formed by bonding the release-treated surfaces of the release film to both surfaces of one adhesive layer. In this case, by peeling off the release film of both sides sequentially or simultaneously, and exposing an adhesive surface, it can bond with optical members, such as an optical film. Examples of the optical film include polarizing films, retardation films, antireflection films, antiglare (anti-glare) films, ultraviolet absorbing films, infrared absorbing films, optical compensation films, brightness enhancement films, and the like.

The adhesive film of the present invention can be used for various optical films for peripheral parts of liquid crystal displays, various optical films for touch panels, various optical films for electronic paper, various optical films for organic EL, etc., including polarizing plates. Fitting.

Moreover, the said adhesive layer can be laminated|stacked on at least one surface of these optical films, and the optical film with an adhesive layer can be produced. 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 Adhesive layer/release film" and so on.

For example, such as "optical film/adhesive layer/release film", in the case of having an adhesive layer protected by a release film, by peeling off the release film to expose the image "optical film/adhesive layer" "Adhesive layer like that, and lamination with other optical films, can obtain the composition such as "optical film/adhesive layer/optical film" that uses adhesive layer for interlayer lamination.

Example

Hereinafter, the present invention will be specifically described by way of examples.

<Preparation of Acrylic Copolymer>

[Example 1]

Nitrogen was introduced into a reaction apparatus equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen introduction pipe to replace the air in the reactor with nitrogen. After that, add 90 parts by weight of butyl acrylate, 10 parts by weight of phenoxyethyl acrylate, 10 parts by weight of diethylacrylamide, 1.0 parts by weight of acrylic acid, 1.0 parts by weight of 4-hydroxybutyl acrylate and solvent (acetic acid ethyl ester) 60 parts by weight. Thereafter, 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator was dropped over 2 hours, and reacted at 65° C. for 6 hours to obtain acrylic acid used in Example 1 with a weight average molecular weight of 500,000. Copolymer Solution 1. A part of the acrylic copolymer was used as a sample for acid value measurement described later.

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

In addition to adjusting the composition of each monomer as described in (A), (B), (C), (D-1) (D-2) of Table 1, the acrylic acid used in Example 1 above Copolymer solution 1 was operated similarly, and the acrylic acid copolymer solution used for Examples 2-5 and Comparative Examples 1-3 was obtained. Here, although the measurement result is not shown in particular, the weight average molecular weight of the copolymer contained in the acrylic copolymer solution of Examples 2-5 and Comparative Examples 1-3 exists in the range of 200,000 to 2,000,000.

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

[Example 1]

Add 0.1 parts by weight of Coronate L-45 (addition product of toluene diisocyanate (TDI) compound) and 0.1 parts by weight of aluminum chelate (aluminum triacetylacetonate) to the acrylic copolymer solution 1 of Example 1 prepared as above And stirring and mixing, the binder composition of Example 1 was obtained. This adhesive composition was coated on a release film made of a silicone resin-coated polyethylene terephthalate (PET) film, and then dried at 90° C. to remove the solvent. Thereafter, by performing an aging treatment for 7 days under an environment of 23° C. and 50% RH, the adhesive film of Example 1 having an adhesive layer made of The binder composition is crosslinked.

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

The adhesive films of Examples 2-5 and Comparative Examples 1-3 were obtained in the same manner as the adhesive film of Example 1 above, except that the composition of the additives was adjusted as described in (E) of Table 1. .

【Table 1】

In Table 1, the numerical value in parentheses represents the numerical value of the weight part of (C) group - (E) group calculated|required by making the total weight of (A) group and (B) group into 100 weight part.

In addition, the compound names corresponding to the abbreviations of the components used in Table 1 are shown in Table 2. Here, Coronate (コロネート, registered trademark) L-45 is a product name of Nippon Polyurethane Industry Co., Ltd., and D-11ON is a product name of Mitsui Chemicals Corporation. TDI toluene diisocyanate, XDI refers to xylylene diisocyanate.

【Table 2】

<Test method and evaluation>

Peel off the release film (PET film coated with silicone resin) from the adhesive films of Examples 1 to 5 and Comparative Examples 1 to 3 to expose the adhesive layer, and transfer the adhesive layer to a polarizing plate (film) on one side.

<Measurement method of adhesive force>

The adhesive layer 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.

This adhesive film was bonded to the non-tin surface of soda lime glass cleaned with acetone using a pinch roller. Thereafter, after autoclaving at 50° C. and 0.5 MPa for 20 minutes, the pressure was returned to an environment of 23° C.×50% RH, and the peel strength of the adhesive film after 1 hour was measured by a tensile tester. Measured according to JIS Z0237 "Adhesive Tape and Adhesive Sheet Test Method", the peel strength when peeled in a direction of 180° at a speed of 300 mm/min is regarded as the adhesive force of the adhesive layer of the adhesive film.

<Adhesion Test Method>

The adhesive layer of the adhesive film of the sample after measuring the adhesive force was visually confirmed, and the adhesiveness was judged in a state of detaching from the polarizing plate (film) of the base material layer.

○... The adhesive layer did not come off from the base material layer at all.

Δ··A part of the adhesive layer is separated from the base material layer and falls off.

×··The adhesive layer peeled off from the base material layer and adhered to the glass of the to-be-adhered body.

<Durability test method>

A 10 cm square adhesive film prepared by the same method as the measurement of the adhesive force was attached to the non-tin surface of the soda lime glass by the same method to obtain a sample. The sample was left in an environment of 60° C.×90% RH for 250 hours, then taken out to an environment of 23° C.×50% RH, and the state of the adhesive film after 1 hour was visually observed to judge durability.

○·· No peeling or foaming occurred in the adhesive film.

Δ··Peeling and foaming occurred in a part of the adhesive film.

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

<Measuring method of refractive index>

The refractive index of the adhesive layer at 23° C. was measured with an Abbe refractometer (manufacturer: ERMA, model: ER-2S).

Table 3 shows the evaluation results.

【table 3】

In the adhesive films of Examples 1 to 5, the adhesive force of the adhesive layer with a thickness of 5 μm is 4.0 N/25 mm or more, the refractive index of the adhesive layer is in the range of 1.47 to 1.50, and the adhesiveness and durability are excellent. Sex is also excellent. That is, the adhesive films of Examples 1 to 5 were able to meet the desired requirements and overcome the problems.

Use the adhesive composition of embodiment 1, and prepare the adhesive film that adhesive layer thickness is 3 μ m, 5 μ m, 10 μ m, 15 μ m, 20 μ m with the same method, and have measured the cohesive force of adhesive layer, will The results are shown in Table 4. It can be seen that the adhesive force of the adhesive layer using the adhesive composition of Example 1 is approximately proportional to the thickness of the adhesive layer as well known.

【Table 4】

The adhesive film of Comparative Example 1 may be because the adhesive composition does not contain a nitrogen-containing monomer, and the adhesive force of the adhesive layer with a thickness of 5 μm is weak. In addition, since it does not contain an aryl group-containing (meth)acrylate monomer, the adhesive layer has a low refractive index. Furthermore, adhesion and durability are also inferior.

In the adhesive film of Comparative Example 2, the adhesive force of the adhesive layer having a thickness of 5 μm was weak because the compounding amount of the carboxyl group-containing copolymerizable vinyl monomer in the adhesive composition was too large. In addition, since it does not contain an aryl group-containing (meth)acrylate monomer, the adhesive layer has a low refractive index. Furthermore, adhesive force and durability are also inferior.

The adhesive film of Comparative Example 3 may be because neither the carboxyl-containing copolymerizable vinyl monomer nor the hydroxyl-containing copolymerizable vinyl monomer is contained in the adhesive composition, and the adhesive film with a thickness of 5 μm The cohesive force of the layer is weak, and the adhesion and durability are also poor.

As such, the adhesive films of Comparative Examples 1-3 cannot meet the required requirements and overcome the problems of the past.

Claims (9)

1. An adhesive layer formed by crosslinking an adhesive composition comprising an acrylic polymer and a crosslinking agent, wherein, The binder composition includes: The aforementioned acrylic polymer, the acrylic polymer is at least one or more of (A) alkyl (meth)acrylate monomers containing 70 to 95 parts by weight of alkyl carbon atoms having C1 to C14 and 5 to 30 parts by weight of (B) at least one (meth)acrylate monomer as a main component of (B) aryl-group-containing (meth)acrylate monomers (A) and (B) A total of 100 parts by weight, 5 to 50 parts by weight of (C) one or more nitrogen-containing vinyl monomers and 0.1 to 5 parts by weight of (D) carboxyl group-containing copolymerizable vinyl monomers and/or A copolymer having a weight average molecular weight of 200,000 to 2 million obtained from at least one of hydroxyl group-containing copolymerizable vinyl monomers; and, 0.01 to 5 parts by weight of the (E) crosslinking agent relative to the total of 100 parts by weight of the (meth)acrylate monomers (A) and (B) as the main components, Moreover, the thickness of the adhesive layer is 1 μm to 20 μm, and the adhesive force when the thickness is 5 μm is 4.0 N/25 mm or more, Moreover, the refractive index of the said adhesive layer is 1.47-1.50. 2. The adhesive layer according to claim 1, wherein, In the acrylic polymer, the carboxyl group-containing copolymerizable vinyl monomer is The content of one or more kinds of monomers is 2.0 parts by weight or less and/or the content of one or more kinds of hydroxyl group-containing copolymerizable vinyl monomers is 5.0 parts by weight or less. 3. An adhesive film formed by forming the adhesive layer according to claim 1 or 2 on one side of a release film, and having a configuration of release film/adhesive layer/release film. 4. An adhesive film obtained by laminating the adhesive layer according to claim 1 or 2 on one surface of a substrate. The film for peripheral parts of a polarizing plate using the adhesive film of Claim 3 or 4. The film for touch panels using the adhesive film of Claim 3 or 4. A film for electronic paper using the adhesive film according to claim 3 or 4. A film for organic EL using the adhesive film according to claim 3 or 4. 9. An optical film with an adhesive layer, which is formed by laminating the adhesive layer according to claim 1 or 2 on at least one surface of the optical film.