JP2012172045A - Adhesive agent composition, adhesive agent layer, and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive agent composition which hardly oozes out like paste under normal temperature and normal pressure, exhibits satisfactory initial adhesive force when dried and crosslinked, is cured easily by light irradiation or heat, and forming an adhesive agent layer having high peeling resistance; and to provide the adhesive agent layer and an adhesive sheet.SOLUTION: The adhesive agent composition contains: an acrylic polymer comprising 50-95 wt.% alkyl (meth)acrylate, 2-40 wt.% cyclic ether group-containing monomer and 3-40 wt.% non-cyclic ether group-containing (meth)acrylate as constituent components; and a cationic photopolymerization initiator or a heat-curing catalyst. The adhesive agent layer is obtained by using the adhesive agent composition. The adhesive sheet is also provided.

Description

  The present invention relates to an adhesive composition, an adhesive layer, and an adhesive sheet in which such an adhesive layer is formed on at least one side of a support.

  In recent years, as an adhesive sheet, a thermosetting type material that is cured by heat treatment has been proposed for bonding applications such as various parts. Such a thermosetting adhesive is excellent in adhesive strength and heat resistance, but is not tacky at room temperature bonding and is difficult to temporarily bond. Therefore, an adhesive sheet that exhibits moderate tackiness as a pressure-sensitive adhesive at the initial stage of adhesion to an adherend and exhibits high adhesion and high heat resistance equivalent to the adhesive after bonding is desired.

  Furthermore, structural adhesives are becoming popular for bonding to reduce the weight of automobiles, etc., but these are very high in strength, but have low viscosity before curing, and are difficult to fix temporarily by themselves. Moreover, there are few things with high transparency. From now on, it is possible to bond a transparent sensor etc. for automobiles, and it has transparency as well as structural adhesive, but it has transparency and does not peel semipermanently. It is believed that the need for adhesives with high strength will increase.

  So far, for example, a curable thermoadhesive sheet containing an acrylic polymer grafted with an epoxy group and a photoinitiator has been proposed (Patent Document 1). A sheet is desired. Some adhesives with high transparency have been proposed (Patent Document 2), but those having higher strength are desired.

JP 2010-138370 A Japanese Patent Laid-Open No. 11-61071

  The present invention is a light that has sufficient initial adhesive strength by drying and crosslinking, is easily cured by light irradiation or heat treatment, forms an adhesive layer having high shear adhesive strength, and is excellent in transparency. It aims at providing the adhesive composition which can form the adhesive sheet for curable type or thermosetting type component fixation.

  Moreover, an object of this invention is to provide the adhesive layer which has the high heat resistance formed with the said adhesive composition, and an adhesive sheet.

  As a result of intensive studies to solve the above problems, the present inventors have found the following adhesive composition and completed the present invention.

That is, the present invention relates to an acrylic polymer comprising 50 to 95% by weight of an alkyl (meth) acrylate, 2 to 40% by weight of a cyclic ether group-containing monomer, and 3 to 40% by weight of a non-cyclic ether group-containing (meth) acrylate as constituent components. And a pressure-sensitive adhesive composition comprising a photocationic polymerization initiator or a thermosetting catalyst.

In the acrylic polymer, it is preferable that the chain containing the cyclic ether group-containing monomer is graft-polymerized to the trunk polymer.

  In the acrylic polymer, the backbone polymer preferably contains the acyclic ether group-containing (meth) acrylate.

  It is preferable to contain 0.1 to 5.0 parts by weight of a cationic photopolymerization initiator or a thermosetting catalyst with respect to 100 parts by weight of the acrylic polymer.

  Further, the adhesive composition preferably contains an isocyanate-based crosslinking agent and / or a tackifier.

  It is preferable that 0.01 to 4 parts by weight of the isocyanate crosslinking agent is contained with respect to 100 parts by weight of the acrylic polymer.

It is preferable to contain 10 to 150 parts by weight of the tackifier with respect to 100 parts by weight of the acrylic polymer.

  The present invention also relates to an adhesive layer obtained from any of the above adhesive compositions.

The present invention also relates to an adhesive sheet in which the above-mentioned adhesive layer is provided on at least one side of a substrate.

  The present invention also relates to an adhesive layer obtained by subjecting the adhesive composition to light irradiation or heat treatment.

  In the adhesive layer, the gel fraction is preferably 70% or more and 98% or less.

In the adhesive layer, the storage elastic modulus is preferably 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ Pa.

  In the adhesive layer, the haze is preferably 4.0 or less.

The adhesive layer preferably has a shear adhesive strength of 350 N / 20 mm or more.

The present invention also relates to an adhesive sheet in which any one of the above adhesive layers is provided on at least one surface of a substrate.

The adhesive composition of the present invention has sufficient initial adhesive force by drying and crosslinking, is easily cured by light irradiation or heat treatment, is easily cured by light irradiation or heat treatment, and has high shear adhesion. A pressure-sensitive adhesive layer can be formed. Furthermore, the adhesive composition of the present invention is an adhesive sheet that maintains fluidity in the process of producing the graft polymer contained therein, is easy to handle, and has excellent processability, final adhesiveness, and heat resistance. Can be provided. Furthermore, by introducing an acrylic monomer having an R ₁ OR ₂ group in the structure by polymerization, it becomes possible to eliminate the turbidity of the polymer and to provide a more transparent adhesive sheet.

The adhesive composition of the present invention comprises alkyl (meth) acrylate 50 to 95% by weight, cyclic ether group-containing monomer 2 to 40% by weight, and acyclic ether group-containing (meth) acrylate 3 to 40% by weight. An acrylic polymer included as a component; and a photocationic polymerization initiator and / or a thermosetting catalyst.

First, as the monomer unit contained in the (meth) acrylic polymer, any (meth) acrylate can be used and is not particularly limited. Here, preferably, for example, an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms is contained in an amount of 50 wt% to 95 wt% of the entire (meth) acrylic polymer.

  In the present specification, the term “alkyl (meth) acrylate” simply refers to a (meth) acrylate having a linear or branched alkyl group. The alkyl group has 4 or more carbon atoms, preferably 4 to 9 carbon atoms. (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

  Specific examples of the alkyl (meth) acrylate include n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, and isopentyl. (Meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl ( (Meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, isomyristyl (meth) acrylate, n-tridecyl (meth) acrylate Rate, n- tetradecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate. Especially, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. can be illustrated and these can be used individually or in combination.

  In this invention, the said alkyl (meth) acrylate is 50 weight% or more with respect to all the monomer components of a (meth) acrylic-type polymer, Preferably it is 55 weight% or more. Moreover, although all the monomers may be alkyl (meth) acrylates, they are preferably 95% by weight or less, and more preferably 90% by weight or less.

In the present invention, the acyclic ether group-containing (meth) acrylate is not particularly limited as long as it is a (meth) acrylate containing an acyclic ether group. For example, an acyclic ether group-containing alkoxyalkyl (meth) acrylate containing a linear or branched alkoxyalkyl group as a side chain alkyl group and not containing a cyclic ether group is preferably used. For example, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, ethoxypropyl (meth) acrylate, methoxybutyl (meth) acrylate, ethoxybutyl (meth) acrylate, methoxyhexyl (meth) acrylate, Ethoxyhexyl (meth) acrylate, methoxyoctyl (meth) acrylate, ethoxyoctyl (meth) acrylate, methoxydecyl (meth) acrylate, ethoxydecyl (meth) acrylate and the like can be used alone or in combination. Further, it may be an acyclic ether group-containing (meth) acrylate containing an aromatic or alicyclic group such as phenoxy (meth) acrylate, methoxyphenyl (meth) acrylate, or methoxycyclohexyl (meth) acrylate.

The acyclic ether group-containing (meth) acrylate is contained in an amount of 3 to 40% by weight, preferably 6 to 35% by weight, based on all monomer components of the (meth) acrylate polymer. By using a non-cyclic ether group-containing (meth) acrylate, compatibility with the cyclic ether group-containing monomer component can be improved, and transparency (haze) can be improved.

  In addition to this, it is preferable that the (meth) acrylic polymer of the present invention contains a hydroxyl group-containing monomer containing at least one hydroxyl group in the alkyl group. That is, this monomer is a monomer containing one or more hydroxyalkyl groups. Here, the hydroxyl group is preferably present at the terminal of the alkyl group. Carbon number of an alkyl group becomes like this. Preferably it is 2-8, More preferably, it is 2-6, More preferably, it is 2-4. By including such a hydroxyl group-containing monomer, there is a positive effect on the position at which hydrogen abstraction occurs during graft polymerization and the compatibility between the graft polymer and the homopolymer of the cyclic ether group-containing monomer generated during graft polymerization. It is considered useful for preparing a graft polymer having good heat resistance.

As such a monomer, a hydroxy (meth) acrylamide monomer having a polymerizable functional group having an unsaturated double bond of a (meth) acryloyl group and having a hydroxyl group can be used without particular limitation. For example, 2-hydroxyethyl (meth) acrylamide, 3-hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (meth) acrylamide, 6-hydroxyhexyl (meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide, 10-hydroxy Examples include hydroxyalkyl (meth) acrylamides such as decyl (meth) acrylamide.

Such a hydroxy (meth) acrylamide monomer is preferably 0.2% by weight or more, more preferably 0.5% by weight or more, preferably with respect to the total amount of monomer components forming the (meth) acrylic polymer. Is 10% by weight or less. Most preferably, it is 1 to 10% by weight.

It is also preferred that a cyclic ether group-containing monomer is copolymerized with the (meth) acrylic polymer.

Here, the cyclic ether group-containing monomer is not particularly limited, but is preferably an epoxy group-containing monomer, an oxetane group-containing monomer, or a combination of both.

Examples of the epoxy group-containing monomer include glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, or 4-hydroxybutyl acrylate glycidyl ether. These may be used alone or in combination. Can be used.

Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, 3-ethyl-3-oxetanylmethyl (meth) acrylate, and 3-butyl-3-oxetanylmethyl. (Meth) acrylate or 3-hexyl-3-oxetanylmethyl (meth) acrylate is exemplified, and these can be used alone or in combination.

The amount of the cyclic ether group-containing monomer is preferably 2% by weight or more, more preferably 3% by weight or more based on the entire (meth) acrylic polymer. Although an upper limit is not specifically limited, 40 weight% or less is preferable. When the amount of the cyclic ether group-containing monomer is 3% by weight or more, the function of the composition as a pressure-sensitive adhesive is sufficiently exhibited. On the other hand, when the amount is 40% by weight or more, tackiness is reduced and initial adhesion is difficult. There is.

  As the monomer component for forming the (meth) acrylic polymer, other copolymerization monomers may be used alone or in combination as long as the object of the present invention is not impaired. Examples of the other comonomer include an aromatic ring-containing monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having an aromatic ring. can give. Specific examples of the aromatic ring-containing monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenol ethylene oxide modified (meth) acrylate, 2-naphthoethyl (meth) acrylate, 2- (4-methoxy-1- And naphthoxy) ethyl (meth) acrylate, phenoxypropyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and polystyryl (meth) acrylate.

  In addition, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; styrene sulfonic acid and allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) Sulfonic acid group-containing monomers such as acrylamide propanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; methoxyethyl (meth) acrylate, ( It is also preferred that (meth) acrylic acid alkoxyalkyl monomers such as ethoxyethyl methacrylate;

  In addition, vinyl monomers such as vinyl acetate, vinyl propionate, styrene, α-methylstyrene, N-vinylcaprolactam; glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) Epoxy group-containing monomers such as acrylate; glycol-based acrylic ester monomers such as (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol; Acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; Bromide group-containing monomers, amino group-containing monomers, imide group-containing monomer, N- acryloyl morpholine, may be used, such as vinyl ether monomers.

  The weight average molecular weight of the (meth) acrylic polymer of the present invention is preferably 600,000 or more, more preferably 700,000 to 3,000,000. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

Such a (meth) acrylic polymer can be produced by appropriately selecting a known production method such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Further, the (meth) acrylic polymer obtained may be either a random copolymer or a block copolymer.

  In solution polymerization, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific example of solution polymerization, the reaction is performed under an inert gas stream such as nitrogen, and a polymerization initiator is added, and the reaction is usually performed at about 50 to 70 ° C. under reaction conditions of about 5 to 30 hours.

  The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of a (meth) acrylic-type polymer can be controlled by the usage-amount of a polymerization initiator and a chain transfer agent, and reaction conditions, The usage-amount is suitably adjusted according to these kinds.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl-2). -Imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 2,2 '-Azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, VA-057) and other azo initiators, and persulfates such as potassium persulfate and ammonium persulfate , Di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl -Oxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3 , 3-tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) ) Peroxides such as cyclohexane, t-butyl hydroperoxide, hydrogen peroxide, peroxides and sodium bisulfite, peroxides and sodium ascorbate Redox initiators combined with Not intended to be.

  The polymerization initiator may be used alone or in combination of two or more, but the total content is 0.005 to 1 part by weight with respect to 100 parts by weight of the monomer. Is preferably about 0.02 to 0.5 parts by weight.

  In order to produce the (meth) acrylic polymer having the weight average molecular weight using, for example, 2,2′-azobisisobutyronitrile as the polymerization initiator, the amount of the polymerization initiator used is a monomer. The amount is preferably about 0.06 to 0.2 part by weight, more preferably about 0.08 to 0.175 part by weight with respect to 100 parts by weight of the total amount of the components.

  Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agent may be used alone or in combination of two or more, but the total content is 0.1 parts by weight with respect to 100 parts by weight of the total amount of monomer components. Less than or equal to

  Examples of the emulsifier used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, ammonium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy Nonionic emulsifiers such as ethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene-polyoxypropylene block polymer are listed. These emulsifiers may be used alone or in combination of two or more.

  Further, as reactive emulsifiers, as emulsifiers into which radical polymerizable functional groups such as propenyl groups and allyl ether groups are introduced, specifically, for example, Aqualon HS-10, HS-20, KH-10, BC-05 BC-10, BC-20 (all of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Soap SE10N (manufactured by ADEKA), and the like. Reactive emulsifiers are preferable because they are incorporated into the polymer chain after polymerization and thus have improved water resistance. The amount of the emulsifier used is more preferably 0.3 to 5 parts by weight and 0.5 to 1 part by weight from the viewpoint of polymerization stability and mechanical stability with respect to 100 parts by weight of the total amount of monomer components.

The glass transition temperature (Tg) of the (meth) acrylic polymer is 250K or less, preferably 240K or less. The glass transition temperature is also preferably 200K or higher. When the glass transition temperature is 250 K or less, the adhesive composition has good heat resistance and excellent internal cohesive strength. Such a (meth) acrylic polymer can be adjusted by appropriately changing the monomer component and composition ratio to be used. Such glass transition temperature is, for example, by solution polymerization, using 0.06 to 0.2 part of a polymerization initiator such as azobisisobityronitrile or benzoyl peroxide, and using a polymerization solvent such as ethyl acetate. And it is obtained by making it react at 50 to 70 degreeC under nitrogen stream for 8 to 30 hours. Here, the glass transition temperature (Tg) is calculated from the following Fox equation.
1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 +
The above-mentioned Tg1, Tg2, Tg3 and the like represent the glass transition temperatures of the individual copolymer components 1, 2, 3, etc. in absolute temperature, and W1, W2, W3 and the like represent the respective copolymer components. The weight fraction. In addition, the glass transition temperature (Tg) of the single polymer was obtained from Polymer Handbook (4th edition, John Wiley & Sons. Inc.).

Next, a solution obtained by diluting the (meth) acrylic polymer thus obtained as it is or by adding a diluent may be subjected to graft polymerization.

Although it does not specifically limit as a diluent, Ethyl acetate or toluene is illustrated.

Graft polymerization is preferably carried out by adding a cyclic ether group-containing monomer and optionally a cyclic ether group-containing monomer and other monomers to a backbone polymer obtained by copolymerizing an alkyl (meth) acrylic polymer with a non-cyclic ether group-containing monomer. Perform by reacting.

Here, the cyclic ether group-containing monomer is not particularly limited, but is preferably an epoxy group-containing monomer, an oxetane group-containing monomer, or a combination of both.

Examples of the epoxy group-containing monomer include glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, or 4-hydroxybutyl acrylate glycidyl ether. These may be used alone or in combination. Can be used.

Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, 3-ethyl-3-oxetanylmethyl (meth) acrylate, and 3-butyl-3-oxetanylmethyl. (Meth) acrylate or 3-hexyl-3-oxetanylmethyl (meth) acrylate is exemplified, and these can be used alone or in combination.

In the case of graft polymerization, the amount of the cyclic ether group-containing monomer is preferably 2 to 40% by weight, and more preferably 4 to 35% by weight. When the cyclic ether group-containing monomer is 2 parts by weight or more with respect to 100 parts by weight of the (meth) acrylic polymer in the case of graft polymerization, the functional expression as a pressure-sensitive adhesive of the composition is sufficient, while 50% by weight. If it is more than the portion, tackiness may be reduced and initial adhesion may be difficult.

  It is also possible to use other monomers that co-graft with the cyclic ether group-containing monomer during the graft polymerization. Such a monomer is not particularly limited as long as it does not contain a cyclic ether group, and examples thereof include alkyl (meth) acrylates having 1 to 9 carbon atoms. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl acrylate and the like. Moreover, alicyclic (meth) acrylates such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate can also be used. These can be used alone or in combination.

When the other monomer co-grafted at the time of grafting is used, the irradiation amount at the time of light irradiation for effecting the adhesive can be lowered. This is presumably because the mobility of the graft chain is increased, or because the compatibility between the graft chain and the by-product ungrafted chain and the backbone polymer is improved.

Such other monomers are also preferably selected from the same monomers as the main chain (trunk), that is, the components of the (meth) acrylic polymer.

When the amount of the monomer other than the cyclic ether group-containing monomer is blended, the weight ratio of the cyclic ether group-containing monomer to the cyclic ether group-containing monomer: other monomer, preferably 90:10 to 10:90. More preferably, it is 80:20 to 20:80. If the content of other monomers is small, the effect of reducing the light irradiation amount for curing may not be sufficient, and if it is large, the peeling resistance after light irradiation may increase.

Graft polymerization conditions are not particularly limited, and can be carried out by methods known to those skilled in the art. In the polymerization, it is preferable to use a peroxide as a polymerization initiator.

The amount of such a polymerization initiator is 0.02 to 5 parts by weight with respect to 100 parts by weight of the meth) acrylic polymer. When the amount of this polymerization initiator is small, it takes too much time for the graft polymerization reaction, and when it is large, many homopolymers of cyclic ether group-containing monomers are formed, which is not preferable.

For example, if the graft polymerization is solution polymerization, a cyclic ether group-containing monomer and a viscosity-adjustable solvent are added to the acrylic copolymer solution, followed by nitrogen substitution, and then a peroxide system such as dibenzoyl peroxide. Although it can carry out by adding 0.02-5 weight part of polymerization initiators, and heating at 50 to 80 degreeC for 4 to 15 hours, it is not limited to this.

The state of the obtained graft polymer (molecular weight, branch polymer branch size, etc.) can be appropriately selected depending on the reaction conditions.

  High transparency can be obtained by setting the blending ratio of the acyclic ether group-containing monomer and the cyclic ether group-containing monomer to about the same amount, but 1: 0.5 to 4.0, preferably 1: 0.6 to 3.0, more preferably 1: 0.7 to 2.0.

  The adhesive composition of the present invention contains the polymer or graft polymer thus obtained and a photocationic polymerization initiator or a thermosetting catalyst.

  As the photocationic polymerization initiator, any photocationic polymerization initiator known to those skilled in the art can be preferably used. More specifically, at least one selected from the group consisting of arylsulfonium hexafluorophosphate salts, triarylsulfonium salts, sulfonium hexafluorophosphate salts, and bis (alkylphenyl) iodonium hexafluorophosphates. Can be used.

  Such a cationic photopolymerization initiator may be used alone or in combination of two or more, but the total content is 100 weight of the (meth) acrylic polymer. 0.1 to 5 parts by weight, and preferably 0.3 to 3 parts by weight with respect to parts.

More specifically, as the thermosetting catalyst, at least one selected from the group consisting of imidazole compounds, acid anhydrides, phenol resins, Lewis acid complexes, amino resins, polyamines, and melamine resins can be used. . Among these, an imidazole compound is particularly preferable, and the imidazole compound is not limited, but 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4- Methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2- Undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazoli Such Mutorimeriteito are exemplified. These compounds are selected in consideration of the curing start temperature and compatibility with the adhesive.

  Among these, an imidazole compound is preferably used because it can be added in a small amount. Examples of the imidazole compound include 2-methylimidazole, 2heptadecylimidazole, 1,2dimethylimidazole, 2phenylimidazole, 2phenyl4methylimidazole, and 1benzyl 2methylimidazole.

  For example, when the adhesive polymer is a water-dispersed emulsion, 1,2-dimethylimidazole is selected, and 1-cyanoethyl is selected for the purpose of preserving storage or for thermosetting at a relatively high temperature. If 2-undecylimidazole is selected and the purpose is to cure at relatively low temperatures, 2-phenylimidazole can be selected.

Such a cyclic ether group thermosetting catalyst may be used alone or as a mixture of two or more, but the total content is 100 parts by weight of the graft polymer. And 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight.

  A cross-linking agent is added to the adhesive composition of the present invention as necessary. Although it does not specifically limit as a crosslinking agent, Isocyanate which is a compound which has two or more isocyanate groups (including the isocyanate reproduction | regeneration functional group which protected the isocyanate group temporarily by the blocking agent or quantification etc.) in 1 molecule. A system crosslinking agent is illustrated.

  Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

  More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, 2,4-tolylene diisocyanate, Aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, polymethylene polyphenyl isocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.), tri Methylolpropane / hexamethylene diisocyanate trimer adduct (product name: Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), hexamethylene diiso Isocyanurate of anate (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.), polyether polyisocyanate, polyester polyisocyanate, and adducts of these with various polyols, isocyanurate bond, burette bond And polyisocyanates polyfunctionalized with allophanate bonds. Of these, it is preferable to use an aliphatic isocyanate because of its high reaction rate.

The isocyanate-based crosslinking agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. On the other hand, it is preferable to contain 0.01 to 4 parts by weight of the isocyanate compound crosslinking agent, more preferably 0.02 to 2 parts by weight, and 0.05 to 1.5 parts by weight. More preferably. It can be appropriately contained in consideration of cohesive force and prevention of peeling in a durability test.

  Moreover, you may use together an organic type crosslinking agent and a polyfunctional metal chelate as a crosslinking agent. Examples of the organic crosslinking agent include epoxy crosslinking agents (referring to compounds having two or more epoxy groups in one molecule). Examples of the epoxy-based crosslinking agent include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, terephthalic acid diglycidyl ester acrylate, spiroglycol diglycidyl ether, and the like. These may be used alone or in combination of two or more.

  A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to 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. 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.

  In the present invention, it is also possible to add an oxazoline-based crosslinking agent or peroxide as a crosslinking agent.

  As the oxazoline-based crosslinking agent, those having an oxazoline group in the molecule can be used without particular limitation. The oxazoline group may be any of a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group. As the oxazoline-based cross-linking agent, a polymer obtained by copolymerizing an unsaturated monomer with an addition-polymerizable oxazoline is preferable, and a compound using 2-isopropenyl-2-oxazoline as the addition-polymerizable oxazoline is particularly preferable. As an example, trade name “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd. can be cited.

The peroxide can be used as appropriate as long as it generates radical active species by heating and proceeds with crosslinking of the base polymer of the adhesive composition, but in consideration of workability and stability, It is preferable to use a peroxide having a one-minute half-life temperature of 80 ° C. to 160 ° C., and more preferable to use a peroxide having a 90 ° C. to 140 ° C.

  Examples of peroxides that can be used include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.), di (4-t-butylcyclohexyl) peroxydicarbonate (1 Minute half-life temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103 0.5 ° C), t-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C), t-butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C), dilauroyl peroxide ( 1 minute half-life temperature: 116.4 ° C.), di-n-octanoyl peroxide (1 minute half-life temperature: 117.4 ° C.), 1,1,3,3-tetramethylbutyl Oxy-2-ethylhexanoate (1 minute half-life temperature: 124.3 ° C), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C), dibenzoyl peroxide (half-minute for 1 minute) Period temperature: 130.0 ° C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.). Especially, since the crosslinking reaction efficiency is excellent, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116. 4 ° C), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C) and the like are preferably used.

  The peroxide half-life is an index representing the decomposition rate of the peroxide, and means the time until the remaining amount of peroxide is reduced to half. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in the manufacturer catalog, for example, “Organic peroxide catalog 9th edition by Nippon Oil & Fats Co., Ltd.” (May 2003) ".

  The peroxide may be used alone or as a mixture of two or more, but the total content is based on 100 parts by weight of the (meth) acrylic polymer. The peroxide is 0.01 to 2 parts by weight, preferably 0.04 to 1.5 parts by weight, and more preferably 0.05 to 1 part by weight. In order to adjust processability, reworkability, cross-linking stability, peelability, and the like, it is appropriately selected within this range.

  In addition, as a measuring method of the peroxide decomposition amount which remained after the reaction process, it can measure by HPLC (high performance liquid chromatography), for example.

More specifically, for example, after about 0.2 g of the adhesive composition after reaction treatment is taken out, immersed in 10 ml of ethyl acetate, and extracted by shaking at 25 ° C. and 120 rpm for 3 hours with a shaker. Let stand at room temperature for 3 days. Next, 10 ml of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μl of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into the HPLC for analysis. The amount of peroxide can be set.

  Although the adhesive layer is formed by the crosslinking agent, in the formation of the adhesive layer, the addition amount of the entire crosslinking agent is adjusted, and the influence of the crosslinking treatment temperature and the crosslinking treatment time is sufficiently considered. There is a need.

  The adhesive composition of the present invention may further contain an epoxy resin or an oxetane resin in order to further improve the adhesive strength and heat resistance.

Examples of the epoxy resin include bisphenol A type, bisphenol F type, bisphenol S type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol AF type, biphenyl type, naphthalene type, fluorene type, phenol novolac type, cresol novolac type. Examples thereof include bifunctional epoxy resins such as trishydroxyphenylmethane type and tetraphenylolethane type and polyfunctional epoxy resins, and glycidylamine types such as hydantoin type and trisglycidyl isocyanurate type. These epoxy resins can be used alone or in combination of two or more.

  These epoxy resins are not limited, but commercially available epoxy resins can be used. Examples of such commercially available epoxy resins include, but are not limited to, for example, bisphenol type epoxy resins such as Japan Epoxy Resin Co., Ltd. jER828, jER806, etc .; alicyclic epoxy resins such as Japan Epoxy Resin Co., Ltd. YX8000, YX8034, etc. ADEKA Co., Ltd. EP4000, EP4005, etc .; polyglycidyl ethers of polyalcohols include known epoxy resins such as Nagase ChemteX Corporation Denacol EX-313, EX-512, EX-614B, EX-810, etc. .

Examples of the oxetane resin include xylylene oxetane such as 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, 3-ethyl-3-{[3-ethyloxetane-3-yl] methoxy. } Methyl} oxetane, 3-ethylhexyloxetane, 3-ethyl-3-hydroxyoxetane, 3-ethyl-3-hydroxymethyloxetane, and other known oxetane resins can be used. These oxetane resins can be used singly or in combination of two or more.

The oxetane resin is not limited, but a commercially available resin can be used. Examples of such commercially available oxetane resins include Aron Oxetane OXT-121, OXT221, OXT101, and OXT212 manufactured by Toa Gosei Co., Ltd., but are not limited thereto.

Such an epoxy resin and an oxetane resin can be used in the adhesive composition of the present invention by either one or a combination of both.

In the present invention, when the epoxy resin and / or oxetane resin is contained with respect to 100 parts by weight of the graft polymer, the total amount thereof is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, preferably Is 100 parts by weight or less, more preferably 70 parts by weight or less. When the total amount is 5 parts by weight or more, a remarkable effect is recognized in improving the adhesive strength and heat resistance. When the total amount exceeds 100 parts by weight, it may not be sufficiently cured.

In the present invention, when an epoxy resin is added to a graft polymer obtained by grafting a cyclic ether group-containing monomer to an acrylic polymer, a composition capable of producing a good adhesive layer in which no glue sticking out occurs before curing. Can be prepared. This is presumably because the grafted cyclic ether group is compatible with the low molecular weight epoxy resin to form a strong adhesive layer structure.

  In addition, a tackifier can be blended in the adhesive composition of the present invention. The tackifier may be used in a total of 10 to 100 parts by weight, preferably 20 to 80 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer.

  Examples of the tackifier include terpene resins from Yasuhara Chemical Co., Ltd. It is considered that by dissolving such a resin in ethyl acetate and blending it in an adhesive, the adhesion at the interface is improved and the adhesive force is improved.

The adhesive composition of the present invention may contain other known additives, such as powders such as colorants and pigments, dyes, surfactants, plasticizers, and tackifiers. , Surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc. Depending on the intended use, it can be added as appropriate. Moreover, you may employ | adopt the redox system which added a reducing agent within the controllable range.

  The adhesive layer of the present invention is preferably formed on at least one side of the support.

The adhesive layer can be formed by applying to the adhesive composition on one side or both sides of the support substrate and drying it, but is not limited thereto. Moreover, an adhesive layer and an adhesive sheet can be formed also by the system etc. which transfer the adhesive layer formed on the separator (release film) to the single side | surface or both surfaces of a support base material. Furthermore, it can also be used as a double-sided pressure-sensitive adhesive sheet or the like without using a separator as a support base material in practical use. The adhesive sheets are used in the form of a sheet or tape.

Examples of the supporting substrate in the adhesive sheet include a porous substrate made of paper, cloth, nonwoven fabric, etc., a plastic film or sheet such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film, a net, a foam, a metal foil, and Appropriate thin leaves such as these laminates can be mentioned. These support base materials are appropriately selected according to the use for which the adhesive sheet is used. The thickness of the supporting substrate is not particularly limited, and is appropriately determined depending on the application.

  More specifically, for example, the adhesive layer is formed by applying the adhesive composition to a release-treated separator or the like, drying and removing the polymerization solvent, etc., and then crosslinking the adhesive composition. A method of transferring a layer to a support such as an optical member after forming the layer, or applying the adhesive composition to the optical member, drying and removing the polymerization solvent, etc., and photocrosslinking the optical adhesive layer It is produced by a method of forming on a member. In applying the adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

A silicone release liner is preferably used as the release-treated separator. In the step of applying the adhesive composition of the present invention on such a liner and drying to form the adhesive layer, as a method of drying the adhesive, according to the purpose, Appropriate methods can be employed. Preferably, a method of heating and drying the coating film is used. The heat drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  Moreover, an adhesive layer can be formed after forming an anchor layer on the surface of a support body or performing various easy-adhesion treatments such as corona treatment and plasma treatment. Moreover, you may perform an easily bonding process on the surface of an adhesive agent layer.

  Various methods are used as a method for forming the adhesive layer. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  The thickness of the adhesive layer is not particularly limited and is, for example, about 1 to 400 μm. Preferably, it is 2-200 micrometers, More preferably, it is 2-150 micrometers.

  When the adhesive layer is exposed, the adhesive layer may be protected with a sheet (separator) that has been subjected to a release treatment until practical use.

  As a constituent material of such a protective separator, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, polyester film, porous materials such as paper, cloth, nonwoven fabric, nets, foamed sheets, metal foils, and these Although an appropriate thin leaf body such as a laminate can be mentioned, a plastic film is preferably used from the viewpoint of excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the adhesive layer, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, chloride film. Examples thereof include a vinyl copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, when the surface of the separator is appropriately subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment, the peelability from the adhesive layer can be further enhanced.

  In addition, the said sheet | seat which carried out the peeling process can be used as a separator of an adhesive-type sheet | seat as it is, and can simplify in the surface of a process.

  The adhesive composition, the adhesive layer, and the adhesive sheet of the present invention are cured by irradiating with specific light, heat treatment, or both treatments. Happens. Therefore, the pressure-sensitive adhesive sheet of the present invention can be easily cured by irradiating light immediately before or after bonding to the adherend. In addition, for example, an adhesive sheet that is interposed between an adherend and a member is preferably used in a form such as a double-sided adhesive tape, and can be cured by irradiation with light at any time after bonding. By such a curing reaction, adhesion to the adherend or adhesion between the adherend and the member is ensured.

Although the light for irradiation is not specifically limited, Preferably, it is active energy rays, such as an ultraviolet-ray, visible light, and an electron beam. The crosslinking treatment by ultraviolet irradiation can be performed using an appropriate ultraviolet source such as a high-pressure mercury lamp, a low-pressure mercury lamp, an excimer laser, or a metal halide lamp. In this case, the irradiation amount of the ultraviolet ray can be appropriately selected according to the required degree of crosslinking, but it is usually preferable to select the ultraviolet ray within the range of 0.2 to 10 J / cm ^2. . Although the temperature at the time of irradiation is not specifically limited, Considering the heat resistance of a support body, about 140 degreeC is preferable.

  When the adhesive composition that constitutes the optical laminated sheet of the present invention contains a thermosetting catalyst, curing occurs by heating. Therefore, the adhesive sheet of the present invention comprises the adherend and the adherend. It can be easily cured by heating before bonding.

  In the case of using a cyclic ether group thermosetting catalyst having a low curing start temperature, the cyclic ether group curing reaction is carried out together with the drying of the solvent and the reaction of the main chain polymer of the adhesive composition in the heat drying step. Occur. Therefore, the pressure-sensitive adhesive sheet of the present invention can be prepared without further heat treatment.

In the case of using a cyclic ether group thermosetting catalyst having a high curing start temperature, only the drying of the solvent and the reaction of the main chain polymer of the adhesive composition proceed in this drying step. Remains. Accordingly, the adhesive sheet of the present invention can be obtained by further heat treatment or as it is.

Conditions such as the temperature of thermosetting are not particularly limited, but are preferably up to about 170 ° C. in consideration of the heat resistance of the support.

  The gel fraction after the curing reaction of the cyclic ether group is 70 to 98%, preferably 80 to 98%, and is an adhesive layer having a very high cohesive force, and its storage elasticity at 23 ° C. The rate is 100,000 to 10,000,000 Pa. On the other hand, if the pressure-sensitive adhesive sheet in which the cyclic ether group remains is heated after adhesion to the adherend, and the curing reaction of the remaining cyclic ether group proceeds, it is called temporary adhesion to the non-adherent and strong adhesion by heating. Both functions can be expressed.

  The following can be adopted as a method for bonding components using the adhesive sheet of the present invention. That is, first, the photocurable or thermosetting adhesive sheet of the present invention formed on a PET separator is attached to an adherend such as glass or metal at room temperature.

In the case of photocuring, light irradiation is subsequently performed before or after the PET separator is peeled off. The normal light irradiation amount is defined within a range of 200 to 2000 mJ / cm ² . Next, the separator is peeled off, and the other adherend is bonded. Heating at 50 to 150 ° C. is performed as necessary after the pressure bonding. In addition, when at least one of the non-adherents is transparent and transmits UV, it can be irradiated after being bonded to both surfaces of the adherend. In that case, it is more strongly bonded.

  In the case of thermosetting, the heat drying temperature is preferably 40 ° C. to 200 ° C., more preferably 50 ° C. to 180 ° C., and particularly preferably 70 ° C. to 170 ° C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

As the drying time, an appropriate time can be appropriately adopted. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  The use of the adhesive composition, the adhesive layer, and the adhesive sheet of the present invention is not particularly limited. For example, the adhesive application for an optical member, and bonding a semiconductor element to an organic substrate or a lead frame Applications, automotive parts adhesion applications, architectural applications, etc., and can be used widely. Hereinafter, in the examples, the evaluation of adhesiveness was performed by evaluating the shear adhesive strength between SUS-BA plates in a model manner.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight. The room temperature standing conditions not specifically defined below are all 23 ° C. and 65% RH (1 hour or 1 week).

<Measurement of weight average molecular weight>
The weight average molecular weight of the obtained (meth) acrylic polymer was measured by GPC (gel permeation chromatography). The sample was prepared by dissolving the sample in dimethylformamide to give a 0.1% by weight solution, which was allowed to stand overnight and then filtered through a 0.45 μm membrane filter.
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
Column: manufactured by Tosoh Corporation, G7000H _XL + GMH _XL + GMH _XL
・ Column size: 7.8mmφ × 30cm each 90cm in total
・ Eluent: Tetrahydrofuran (concentration 0.1% by weight)
・ Flow rate: 0.8ml / min
・ Detector: Differential refractometer (RI)
-Column temperature: 40 ° C
・ Injection volume: 100 μl
・ Standard sample: Polystyrene

<Measurement of gel fraction>
The dried and crosslinked adhesive (initial weight W1) was immersed in an ethyl acetate solution and allowed to stand at room temperature for 1 week, then the insoluble matter was taken out and the dried weight (W2) was measured. I asked for it.
Gel fraction = (W2 / W1) × 100

<Haze>
Using an adhesive sheet sample with a width of 30 mm obtained in Examples and Comparative Examples, using an M-Kurakami Color Research Laboratory Reflection / Transmittance Meter HR-100 type at 25 ° C., using D-65 light It measured (%) according to JISK-7136.

<Measuring method of dynamic viscoelasticity>
The dynamic viscoelasticity of the adhesive which was heat-treated at 150 ° C. for 1 hour was measured.
Device: ARES manufactured by TA Instruments
Deformation mode: Torsion measurement frequency: Constant frequency 1 Hz
Temperature increase rate: 5 ° C / min Measurement temperature: From the glass transition temperature of the adhesive to 160 ° C Measurement shape: Parallel plate 8.0mmφ
Sample thickness: 0.5-2mm (initial stage)
The storage elastic modulus (G ′) at 23 ° C. was read.

Example 1
(Preparation of acrylic polymer)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 85 parts by weight of n-butyl acrylate (BA), 15 parts by weight of methoxyethyl acrylate (MEA), 4-hydroxybutyl acrylate (HBA) ) 3 parts by weight, 0.12 part by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was added together with 200 parts by weight of ethyl acetate, and nitrogen gas was introduced while gently stirring to replace the nitrogen for 1 hour. Thereafter, a polymerization reaction was carried out for 10 hours while maintaining the liquid temperature in the flask at around 55 ° C. to prepare an acrylic polymer solution having a weight average molecular weight of 900,000. The glass transition temperature of the obtained acrylic polymer was 233K.

(Preparation of graft polymer)
The obtained acrylic polymer solution was diluted with ethyl acetate so that the solid content was 25% to prepare a diluted solution (I). In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 20 parts by weight of 4-hydroxybutyl acrylate glycidyl ether (4HBAGE) and 2- After adding 20 parts by weight of ethylexyl acrylate (2EHA) and 0.2 part of benzoyl peroxide, introducing nitrogen gas with gentle stirring and replacing with nitrogen for 1 hour, the liquid temperature in the flask was kept at around 65 ° C. For 4 hours and then at 70 ° C. for 4 hours to obtain a graft polymer solution.

(Formation of adhesive layer)
Subsequently, 0.1 parts by weight of trimethylolpropane adduct of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) (NCO), 100 parts by weight of the solid content of the graft polymer solution thus obtained, 0.1 parts by weight of arylsulfonium hexafluorophosphate (manufactured by LAMBERTI, ESACURE 1064) as an initiator, and 20 parts by weight of phenol-modified terpene resin (Yasuhara Chemical, YS-Polystar T-145, softening point 145 ° C.) as a tackifier The adhesive solution was prepared by blending.

The above adhesive solution is applied to one side of a 38 μm polyethylene terephthalate (PET) film (Mitsubishi Resin “MRF-38”) subjected to silicone treatment, and the thickness of the adhesive layer after drying is 100 μm. This was applied and dried at 120 ° C. for 3 minutes to prepare a test sample.

(Light irradiation)
Next, a 10 mm × 10 mm sample piece was cut out from the test sample, attached to a 0.4 mm thick BA plate (SUS403 steel plate surface finish BA steel plate), the PET film was peeled off, and 2 kg of the same BA2 plate was also applied to the opposite side. A roll was pasted once (BA plate / sample / BA plate). The shearing adhesive force (peeling speed 10 mm / min) at this time is measured and set as the adhesive force when no light is irradiated. After affixing to one side of the BA plate, the sample surface was irradiated with 1 J / cm ² light with a meta-harass UV lamp, and then the opposite side of the BA plate was affixed and dark reaction treatment (60 ° C., 48 hours) was performed. Do. The shear adhesive strength is measured with this sample, and is defined as the adhesive strength during light irradiation.

(Formation of adhesive layer) Sample for gel fraction measurement: 1B
The above adhesive solution was applied to one side of a 38 μm PET film (MRF-38, manufactured by Mitsubishi Plastics) with silicone treatment so that the thickness of the adhesive layer after drying was 20 μm. And it was made to dry at 120 degreeC for 3 minute (s), the test sample 1B was produced, and MRF-38 was bonded together also to the adhesive layer surface. The gel fraction is measured without irradiating light, and this is defined as the gel fraction when no light is irradiated.

The test sample 1B is irradiated with 1 J / cm ² light with the composition of a meta-harara UV lamp and then subjected to a dark reaction treatment (60 ° C. × 48 hours). The gel fraction is measured with this sample to obtain the gel fraction at the time of light irradiation.

Examples 2-11, Comparative Examples 1-2
In the same procedure as in Example 1, an adhesive layer was formed according to the formulation shown in the table. In Examples 5 and 6, a triarylsulfonium salt (manufactured by San Apro, CPI-200K) was used as a photoinitiator.

Table 1 shows the evaluation results of the adhesive strength performed on the samples obtained in the above Examples and Comparative Examples.

That is, the present invention includes 50 to 95% by weight of an alkyl (meth) acrylate, 2 to 40% by weight of a cyclic ether group-containing monomer, and 3 to 40% by weight of a noncyclic ether group-containing (meth) acrylate (meth). The present invention relates to an adhesive composition comprising an acrylic polymer; and a photocationic polymerization initiator or a thermosetting catalyst.

In the (meth) acrylic polymer, the chain containing the cyclic ether group-containing monomer is preferably graft-polymerized to the trunk polymer.

In the (meth) acrylic polymer, the trunk polymer preferably contains the acyclic ether group-containing (meth) acrylate.

It is preferable to contain 0.1 to 5.0 parts by weight of a photocationic polymerization initiator or a thermosetting catalyst with respect to 100 parts by weight of the (meth) acrylic polymer.

It is preferable that 0.01 to 4 parts by weight of the isocyanate crosslinking agent is contained with respect to 100 parts by weight of the (meth) acrylic polymer.

It is preferable to contain 10 to 150 parts by weight of the tackifier with respect to 100 parts by weight of the (meth) acrylic polymer.

The adhesive layer preferably has a shear adhesive strength of 350 N / cm ² or more.

The adhesive composition of the present invention comprises alkyl (meth) acrylate 50 to 95% by weight, cyclic ether group-containing monomer 2 to 40% by weight, and acyclic ether group-containing (meth) acrylate 3 to 40% by weight. A (meth) acrylic polymer contained as a component; and a photocationic polymerization initiator and / or a thermosetting catalyst.

The gel fraction after the curing reaction of the cyclic ether group is 70 to 98%, preferably 80 to 98%, and is an adhesive layer having a very high cohesive force, and its storage elasticity at 23 ° C. The rate is between 100,000 and 10000000 Pa. On the other hand, if the pressure-sensitive adhesive sheet in which the cyclic ether group remains is heated after adhesion to the adherend, and the curing reaction of the remaining cyclic ether group proceeds, it is called temporary adhesion to the non-adherent and strong adhesion by heating. Both functions can be expressed.

In the case of photocuring, light irradiation is subsequently performed before or after the PET separator is peeled off. Usually, the amount of light irradiation is defined within the range of 200 to 2000 mJ / cm ² . Next, the separator is peeled off, and the other adherend is bonded. Heating at 50 to 150 ° C. is performed as necessary after the pressure bonding. In addition, when at least one of the non-adherents is transparent and transmits UV, it can be irradiated after being bonded to both surfaces of the adherend. In that case, it is more strongly bonded.

In the case of thermosetting, the heat drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

As the drying time, an appropriate time can be appropriately adopted. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

Claims (15)

An acrylic polymer containing 50 to 95% by weight of an alkyl (meth) acrylate, 2 to 40% by weight of a cyclic ether group-containing monomer, and 3 to 40% by weight of an acyclic ether group-containing (meth) acrylate as constituents; and a photocationic system An adhesive composition comprising a polymerization initiator or a thermosetting catalyst. The adhesive composition according to claim 1, wherein in the acrylic polymer, a chain containing the cyclic ether group-containing monomer is graft-polymerized to a trunk polymer.   The adhesive composition according to claim 2, wherein in the acrylic polymer, the backbone polymer includes the acyclic ether group-containing (meth) acrylate.   Adhesion according to any one of claims 1 to 3, comprising 0.1 to 5.0 parts by weight of a photocationic polymerization initiator or a thermosetting catalyst with respect to 100 parts by weight of the acrylic polymer. Adhesive composition.   Furthermore, the adhesive composition of any one of Claims 1-4 formed by containing an isocyanate type crosslinking agent and / or a tackifier.   The pressure-sensitive adhesive composition according to claim 5, comprising 0.01 to 4 parts by weight of the isocyanate crosslinking agent with respect to 100 parts by weight of the acrylic polymer. The pressure-sensitive adhesive composition according to claim 5, comprising 10 to 150 parts by weight of the tackifier with respect to 100 parts by weight of the acrylic polymer.   The adhesive layer obtained from the adhesive composition in any one of Claims 1-7. An adhesive sheet, wherein the adhesive layer according to claim 8 is provided on at least one side of a substrate.   A pressure-sensitive adhesive layer obtained by subjecting the pressure-sensitive adhesive composition according to claim 1 to light irradiation or heat treatment.   The adhesive layer according to claim 10, wherein the gel fraction is 70% or more and 98% or less. The adhesive layer of Claim 10 or 11 whose storage elastic modulus is 1.0 * 10 < ⁵ > -1.0 * 10 < ⁷ > Pa.   The adhesive layer according to any one of claims 10 to 12, wherein the haze is 4.0 or less. The adhesive layer according to any one of claims 10 to 13, wherein the shear adhesive strength is 350 N / 20 mm or more. The adhesive sheet which provided the adhesive layer of any one of Claims 10-14 on the at least single side | surface of the base material.