JP2022085858A - Photocurable adhesive composition and adhesive film - Google Patents

Abstract

To provide a photocurable adhesive composition which is less corrosive to a metal member, has good adhesive properties, and hardly causes thickening and gelling due to increase in molecular weight even under a high temperature condition during coating.SOLUTION: There is provided a photocurable adhesive composition which comprises a (meth)acrylic polymer (A), a multi-functional (meth)acrylic monomer (B), and a photopolymerization initiator (C), wherein the (meth)acrylic polymer (A) is a copolymer containing a cyclized polymerizable monomer (a1) and an alkyl (meth)acrylate (a2) as essential constituent monomers, the weight ratio of the cyclized polymerizable monomer (a1) in a monomer constituting the (meth)acrylic polymer (A) is 1 to 20 wt.%, and the (meth)acrylic polymer (A) has a weight average molecular weight of 100000 to 500000, an acid value of 4 mgKOH/g or less, and a hydroxyl value of 3 mgKOH/g or less.SELECTED DRAWING: None

Description

The present invention relates to a photocurable pressure-sensitive adhesive composition and a pressure-sensitive adhesive film.

Conventionally, as an acrylic pressure-sensitive adhesive, a monomer having an alkyl (meth) acrylate such as 2-ethylhexyl acrylate as a main component and having an acid group represented by a carboxyl group such as acrylic acid as a component for imparting cohesive force. A copolymer having a relatively low glass transition point and having adhesiveness obtained by copolymerizing with (for example, see Patent Document 1) is used. However, it is generally known that acid groups easily corrode metal materials, and there is a problem in using an acrylic pressure-sensitive adhesive containing an acid group for bonding electronic components such as transparent electrode sensors such as touch panels. be.

In order to prevent corrosion of metal materials, a method of replacing an acid group in a resin with a hydroxyl group having less corrosiveness has been adopted (see, for example, Patent Document 2). However, the hydroxyl group has higher reactivity with the ester moiety of the alkyl (meth) acrylate component than the carboxyl group, and at high temperatures, thickening and gelation due to the increase in molecular weight due to cross-linking are likely to occur, and workability during coating is improved. There is a problem that gets worse. Further, since the hydroxyl group has a lower cohesive force than the carboxyl group, it is necessary to introduce a large amount of the hydroxyl group into the acrylic pressure-sensitive adhesive in order to develop the adhesive physical characteristics, which causes thickening and gelation easily.

Further, an example in which a cyclized polymerizable monomer is used as a monomer of an acrylic pressure-sensitive adhesive as a pressure-sensitive adhesive capable of achieving both adhesiveness and corrosiveness of a metal material has been reported (see, for example, Patent Document 3). ). By using the cyclization polymerizable monomer, both corrosion suppression of the metal material and adhesiveness (improvement of the cohesive force of the adhesive) are achieved. However, the pressure-sensitive adhesive requires a cross-linking reaction after coating in order to improve the holding power and the cohesive power at a high temperature, and the technique of Patent Document 3 requires a certain amount of hydroxyl group-containing monomer as a cross-linking point. The problems of thickening and gelation have not been solved yet.

Japanese Unexamined Patent Publication No. 2004-143420 Japanese Unexamined Patent Publication No. 2020-76073 Japanese Unexamined Patent Publication No. 2015-3960

The present invention provides a photocurable pressure-sensitive adhesive composition that is less corrosive to metal members, has good adhesive properties, and is less likely to cause thickening or gelation due to an increase in molecular weight even under high temperature conditions during coating. The purpose is.

The present inventors have arrived at the present invention as a result of studies for achieving the above object. That is, the present invention is a photocurable pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A), a polyfunctional (meth) acrylic monomer (B), and a photopolymerization initiator (C). The meta) acrylic polymer (A) is a copolymer containing a cyclization polymerizable monomer (a1) and an alkyl (meth) acrylate (a2) as essential constituent monomers, and is the (meth) acrylic polymer (meth) acrylic polymer (meth). The weight ratio of the cyclizable polymerizable monomer (a1) in the monomers constituting A) is 1 to 20% by weight, and the weight average molecular weight of the (meth) acrylic polymer (A) is 100,000 to 500,000. A photocurable pressure-sensitive adhesive composition in which the (meth) acrylic polymer (A) has an acid value of 4 mgKOH / g or less and a hydroxyl value of 3 mgKOH / g or less; at least one surface of the substrate. In addition, it is a pressure-sensitive adhesive film having a pressure-sensitive adhesive layer formed from the photocurable pressure-sensitive adhesive composition.

The photocurable pressure-sensitive adhesive composition of the present invention has the effects of less corrosion of metal members, good adhesive properties, high heat resistance, low melt viscosity, and excellent coatability.
The heat resistance means that the molecular weight does not easily change when the product is allowed to stand under high temperature conditions for a certain period of time.

<Photo-curing adhesive composition>
The photocurable pressure-sensitive adhesive composition of the present invention is a photo-curable pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A), a polyfunctional (meth) acrylic monomer (B), and a photopolymerization initiator (C). The (meth) acrylic polymer (A) is a copolymer containing a cyclization polymerizable monomer (a1) and an alkyl (meth) acrylate (a2) as essential constituent monomers, and is the above-mentioned (meth) acrylic polymer (A). The weight ratio of the cyclized polymerizable monomer (a1) in the monomer constituting the (meth) acrylic polymer (A) is 1 to 20% by weight, and the weight average molecular weight of the (meth) acrylic polymer (A) is Is 100,000 to 500,000, the acid value of the (meth) acrylic polymer (A) is 4 mgKOH / g or less, and the hydroxyl value is 3 mgKOH / g or less.
In the present invention, "(meth) acrylic" means "acrylic and / or methacrylic", and "(meth) acrylate" means "acrylate and / or methacrylate".

<(Meta) acrylic polymer (A)>
The (meth) acrylic polymer (A) is a copolymer containing a cyclization polymerizable monomer (a1) and an alkyl (meth) acrylate (a2) as essential constituent monomers, and is the (meth) acrylic polymer. The weight ratio of the cyclizable polymerizable monomer (a1) in the monomer constituting (A) is 1 to 20% by weight, and the weight average molecular weight of the (meth) acrylic polymer (A) is 100,000 to 50%. The acid value is 4 mgKOH / g or less, and the hydroxyl value is 3 mgKOH / g or less.

The cyclization polymerizable monomer (a1) has two or more radically polymerizable carbon-carbon double bonds in one molecule, and these double bonds form a ring structure in the molecule during radical polymerization. From the viewpoint of adhesiveness, it is preferable that the monomer forms a cyclic ether (heterocyclic ring) at the time of forming the ring structure. When the monomer forms a cyclic ether at the time of forming the ring structure, the polymer can be a polymer having an ether bond as a polar group near the main chain of the (meth) acrylic polymer (A), and has high adhesiveness. Tend to be. Such monomers include methyl α-allyloxymethyl acrylate (forming a 5-membered ring when forming a ring structure) and methyl α-allyloxyethyl acrylate (forming a 6-membered ring when forming a ring structure). Is done.
One type of cyclization polymerizable monomer (a1) may be used, or two or more types may be used in combination.
Examples of the cyclization polymerizable monomer (a1) include a monomer (a11) represented by the following general formula (1). The monomer (a11) can form a 5-membered cyclic ether when the ring structure is formed.

In formula (1), R ¹ represents an organic group having 1 to 30 carbon atoms. R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are independently hydrogen atoms or alkyl groups having 1 to 6 carbon atoms, respectively.

When R ² to R ⁶ are alkyl groups, the alkyl groups may be linear or branched. Specific examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a neopentyl group and a hexyl group.

A preferred embodiment of the monomer (a11) is a compound represented by the following general ^formula ( ² ) in which R5 and R6 are hydrogen atoms from the viewpoint of polymerizable property and adhesiveness, and a further preferred embodiment is a compound represented by the following general formula (2). This is the case of α- (allyloxymethyl) acrylate ( ^a111 ) in which all of ^R2 to R6 are hydrogen atoms.

The organic group having 1 to 30 carbon atoms of R ¹ may be linear, branched or cyclic. From the viewpoint of polymerizable property and adhesiveness, the organic group preferably has 1 to 18 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 1 to 8 carbon atoms.
Examples of the organic group include a hydrocarbon skeleton, a hydrocarbon skeleton containing an ether bond, and the like.

The hydrocarbon skeleton includes a chain saturated hydrocarbon group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a neopentyl group, a hexyl group, an octyl group, a 2-ethylhexyl group, etc.) and an alicyclic group. Hydrocarbon groups (eg, cyclohexyl group, cyclohexylmethyl group, isobornyl group, adamantyl group, dicyclopentanyl group, dicyclopentenyl group, etc.), aromatic hydrocarbon groups (eg, phenyl group, benzyl group, naphthyl group, anthranyl) Basics, etc.). These groups may have substituents. Preferably, it is a chain saturated hydrocarbon group which may have a substituent.

Examples of the organic group consisting of a hydrocarbon skeleton containing an ether bond include the above-mentioned chain saturated hydrocarbon group (for example, methyl group, ethyl group, propyl group, butyl group, amyl group, neopentyl group, hexyl group, octyl group, 2). -Ethylhexyl group, etc.), alicyclic hydrocarbon group (eg, cyclohexyl group, cyclohexylmethyl group, isobornyl group, adamantyl group, dicyclopentanyl group, dicyclopentenyl group, etc.), aromatic hydrocarbon group (eg, phenyl). A group having an oxygen atom inserted into at least one carbon-carbon bond constituting (group, benzyl group, naphthyl group, anthranyl group, etc.) can be mentioned.

Examples of the substituent include halogen groups such as a fluoro group, a chloro group, a bromo group and an iodine group.

Examples of such an organic group include a chain saturated hydrocarbon group having an ether bond such as a methyloxyethyl group and an ethyloxyethyl group; and a chain ether bond such as a cyclohexyloxyethyl group and a dicyclopentenyloxyethyl group. Alicyclic hydrocarbon group having; aromatic aliphatic hydrocarbon group having chain ether bond such as phenoxyethyl group, phenoxyethoxyethyl group; glycidyl group, 3,4-epoxycyclohexylmethyl group, tetrahydrofuranyl group, tetrahydrofurfuryl Cyclic ether groups such as groups are preferred, but are not limited thereto.

Specifically, as the α- (allyloxymethyl) acrylate (a111),
(1) Chain-saturated hydrocarbon group-containing α- (allyloxymethyl) acrylate:
Methyl α-allyl oxymethyl acrylate, ethyl α-allyl oxymethyl acrylate, n-propyl α-allyl oxymethyl acrylate, i-propyl α-allyl oxymethyl acrylate, n-butyl α-allyl oxymethyl acrylate , Α-allyloxymethylacrylate s-butyl, α-allyloxymethylacrylate t-butyl, α-allyloxymethylacrylate n-pentyl, α-allyloxymethylacrylate s-pentyl, α-allyloxymethyl T-pentyl acrylate, neopentyl α-allyl oxymethyl acrylate, n-hexyl α-allyl oxymethyl acrylate, s-hexyl α-allyl oxymethyl acrylate, n-heptyl α-allyl oxymethyl acrylate, α- N-octyl allyloxymethylacrylate, s-octyl s-octyl oxymethylacrylate, t-octyl α-allyloxymethyl acrylate, 2-ethylhexyl α-allyl oxymethyl acrylate, nonyl α-allyl oxymethyl acrylate , Α-Allyloxymethylacrylate decyl, α-allyloxymethylacrylate undecyl, α-allyloxymethylacrylate lauryl, α-allyloxymethylacrylate tridecyl, α-allyloxymethylacrylate myristyl, α-allyloxy Pentadecyl methyl acrylate, cetyl α-allyl oxymethyl acrylate, heptadecyl α-allyl oxymethyl acrylate, stearyl α-allyl oxymethyl acrylate, nonadesyl α-allyl oxymethyl acrylate, eicosil α-allyl oxymethyl acrylate, Ceryl α-allyloxymethyl acrylate, mericyl α-allyloxymethyl acrylate, etc.;

(2) Hydroxy-substituted chain saturated hydrocarbon group-containing α- (allyloxymethyl) acrylate:
Hydroxyethyl α-allyl oxymethyl acrylate, hydroxypropyl α-allyl oxymethyl acrylate, hydroxy butyl α-allyl oxymethyl acrylate, etc.;

(3) Halogen-substituted chain saturated hydrocarbon group-containing α- (allyloxymethyl) acrylate:
Fluoroethyl α-allyloxymethylacrylic acid, difluoroethyl α-allyloxymethylacrylic acid, chloroethyl α-allyloxymethylacrylic acid, dichloroethyl α-allyloxymethylacrylic acid, bromoethyl α-allyloxymethylacrylic acid, α- Dibromoethyl allyloxymethyl acrylate, etc .;

(4) Α- (allyloxymethyl) acrylate containing an alicyclic hydrocarbon group:
Cyclopentyl α-allyloxymethylacrylic acid, cyclopentylmethyl α-allyloxymethylacrylate, cyclohexylα-allyloxymethylacrylic acid, cyclohexylmethylα-allyloxymethylacrylic acid, 4-methylcyclohexylα-allyloxymethylacrylic acid, α-allyloxymethylacrylic acid 4-t-butylcyclohexyl, α-allyloxymethylacrylic acid tricyclodecanyl, α-allyloxymethylacrylic acid isobornyl, α-allyloxymethylacrylic acid adamantyl, α-allyloxymethylacrylic acid Dicyclopentanyl acid, dicyclopentenyl α-allyloxymethylacrylate, etc.;

(5) Aromatic hydrocarbon group-containing α- (allyloxymethyl) acrylate:
phenyl α-allyl oxymethyl acrylate, methyl phenyl α-allyl oxymethyl acrylate, dimethyl phenyl α-allyl oxymethyl acrylate, trimethyl phenyl α-allyl oxymethyl acrylate, 4-t- allyl oxymethyl acrylate Butylphenyl, benzyl α-allyloxymethylacrylate, diphenylmethylα-allyloxymethylacrylate, diphenylethyl α-allyloxymethylacrylate, triphenylmethylα-allyloxymethylacrylate, α-allyloxymethylacrylate Naftyl, anthranil α-allyloxymethylacrylate, etc .;

(6) Chain-saturated hydrocarbon group-containing α- (allyloxymethyl) acrylate having a chain ether bond:
methoxyethyl α-allyloxymethylacrylic acid, methoxyethoxyethyl α-allyloxymethylacrylate, methoxyethoxyethoxyethyl α-allyloxymethylacrylic acid, 3-methoxybutyl α-allyloxymethylacrylic acid, α-allyloxymethyl Ethoxyethyl acrylate, ethoxyethoxyethyl α-allyloxymethyl acrylate, etc .;

(7) An alicyclic hydrocarbon group-containing α- (allyloxymethyl) acrylate having a chain ether bond:
Cyclopentoxyethyl α-allyloxymethylacrylate, cyclohexyloxylethyl α-allyloxymethylacrylate, cyclopentoxyethoxyethyl α-allyloxymethylacrylate, cyclohexyloxyethoxyethyl α-allyloxymethylacrylate, α- Dicyclopentenyloxyethyl allyloxymethylacrylic acid, etc .;

(8) α- (allyloxymethyl) acrylate containing an aromatic aliphatic hydrocarbon group having a chain ether bond:
Phenoxyethyl α-allyloxymethylacrylate, phenoxyethoxyethyl α-allyloxymethylacrylate, etc.;

(9) Cyclic ether group-based saturated hydrocarbon group-containing α- (allyloxymethyl) acrylate:
glycidyl α-allyloxymethylacrylic acid, β-methylglycidyl α-allyloxymethylacrylic acid, β-ethylglycidyl α-allyloxymethylacrylic acid, α-allyloxymethylacrylic acid 3,4-epoxycyclohexylmethyl, α- 2-oxetanmethyl allyloxymethylacrylic acid, 3-methyl-3-oxetanmethyl α-allyloxymethylacrylic acid, 3-ethyl-3-oxetanmethyl α-allyloxymethylacrylic acid, tetrahydrofura α-allyloxymethylacrylic acid Nyl, tetrahydrofurfuryl α-allyloxymethylacrylate, tetrahydropyranyl α-allyloxymethylacrylate, dioxazolanyl α-allyloxymethylacrylate, dioxanyl α-allyloxymethylacrylate, etc.;

Of these α- (allyloxymethyl) acrylates, methyl α-allyloxymethylacrylate and ethyl α-allyloxymethylacrylate are selected from the viewpoint of cyclization polymerizable property, tackiness and stability under high temperature conditions. It is preferable, and more preferably, α-allyloxymethyl acrylate methyl.

The α- (allyloxymethyl) acrylate (a111) can be produced, for example, by the method disclosed in International Publication No. 2010/114077.
For example, as a method for producing α- (allyloxymethyl) acrylate, a method of carrying out the following reaction steps (i) to (iii) is preferably mentioned. Further, it is preferable to use an amine-based catalyst in all of these reaction steps. That is, it is also one of the preferred embodiments of the present invention that these reaction steps include a step of reacting in the presence of an amine-based catalyst.
(I) A step of reacting an acrylic acid ester with paraformaldehyde to obtain α- (hydroxymethyl) acrylate.
(Ii) A step of obtaining 2,2'-[oxybis (methylene)] bis acrylate from α- (hydroxymethyl) acrylate.
(Iii) A step of reacting 2,2'-[oxybis (methylene)] bis acrylate with allyl alcohol to produce α- (allyl oxymethyl) acrylate and α- (hydroxymethyl) acrylate.
Further, a method of producing from a lower ester of α-allyloxymethylacrylic acid such as methyl α-allyloxymethylacrylate or ethyl α-allyloxymethylacrylate by using a transesterification reaction is also preferable.

Examples of the alkyl (meth) acrylate (a2) include an alkyl (meth) acrylate having an alkyl group having 1 to 12 carbon atoms from the viewpoint of adhesiveness.
In (a2), one kind may be used, or two or more kinds may be used in combination.

The alkyl group includes a linear group or a branched group, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group and a t-butyl group. , N-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-ethylpropyl group, 1,1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group , N-hexyl group, 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group, n-heptyl group, 1-methylhexyl group, n-octyl group, isooctyl group, 2 -Ethylhexyl group, n-nonyl group, isononyl group, n-decyl group, isodecyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group and the like can be mentioned.

Specifically, as (a2), methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and 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, decyl (meth) acrylate , Undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate and the like.
As the alkyl (meth) acrylate (a2), n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate are preferable, and more preferably n-butyl acrylate and 2-ethylhexyl, from the viewpoint of adhesiveness. It is an acrylate.

In the present invention, the (meth) acrylic polymer (A) may be a copolymer containing a cyclization polymerizable monomer (a1) and an alkyl (meth) acrylate (a2) as essential constituent monomers, and may be polar. Monomer having a group (carboxyl group, hydroxyl group, amino group and amide group) {For example, a monomer having a hydroxyl group (a3), a monomer having a carboxyl group (a4) and a monomer having a nitrogen atom (for example) It may contain a5) etc.}, another monomer (a6) having no polar group, etc. as a constituent monomer.
One type may be used for each of (a3) to (a6), or two or more types may be used in combination.

Examples of the monomer (a3) having a hydroxyl group include hydroxyalkyl (meth) acrylates having a hydroxyalkyl group having 2 to 8 carbon atoms {for example, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth). Acrylate, 2-hydroxybutyl (meth) acrylate, etc.}, (meth) acrylic acid monoesteride of polyalkylene (alkylene group having 2 to 8 carbon atoms) glycol {for example, polyethylene glycol mono (meth) acrylate, etc.} and the like. Be done.

Examples of the monomer (a4) having a carboxyl group include (meth) acrylic acid, 2-carboxyethyl (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, citraconic acid, and mesaconic acid. Examples thereof include carboxylic acids having an unsaturated bond.

Examples of the monomer (a5) having a nitrogen atom include (meth) acrylamide and N-alkyl (meth) acrylamide {including those having an alkyl group having 1 to 6 carbon atoms, for example, N-methylacrylamide and the like}. N, N-dialkyl (meth) acrylamide {Alkyl groups each contain 1 to 6 carbon atoms independently, for example, N, N-dimethylacrylamide, N-ethyl-N-methyl- (meth) acrylamide, etc. };;
Primary amino group-containing monomer {alkenylamine with 3 to 6 carbon atoms [(meth) allylamine, crotylamine, etc.], aminoalkyl (2 to 6 carbon atoms) (meth) acrylate [aminoethyl (meth) acrylate, etc.]} ;
Secondary amino group-containing monomer {monoalkylaminoalkyl (meth) acrylate [those having an aminoalkyl group (2 to 6 carbon atoms) in which one alkyl group having 1 to 6 carbon atoms is bonded to a nitrogen atom; for example, N. -T-butylaminoethyl (meth) acrylate and N-methylaminoethyl (meth) acrylate, etc.], dialkenylamine with 6 to 12 carbon atoms [di (meth) allylamine, etc.]};
Tertiary amino group-containing monomer {dialkylaminoalkyl (meth) acrylate [those having an aminoalkyl group (2 to 6 carbon atoms) in which two alkyl groups having 1 to 6 carbon atoms are bonded to a nitrogen atom; for example, N, N-dimethylaminoethyl (meth) acrylate and N, N-diethylaminoethyl (meth) acrylate, etc.], alicyclic (meth) acrylate having a nitrogen atom [morpholinoethyl (meth) acrylate, etc.], aromatic monomer [N- (N', N'-diphenylaminoethyl) (meth) acrylamide, N, N-dimethylaminostyrene, 4-vinylpyridine, 2-vinylpyridine, N-vinylpyrrole, N-vinylpyrrolidone and N-vinyl Thiopyrolidone, etc.]}, and these hydrochlorides, sulfates, phosphates, lower alkyl (1 to 8 carbon atoms) monocarboxylic acid (acetic acid, propionic acid, etc.) salts and the like can be mentioned.

The other monomer (a6) is, for example, a monomer based on a polyolefin having a (meth) acryloyl group {polyolefin (hydrogen polymer), and specifically, an alken having 2 to 10 carbon atoms [for example, Ethylene, propylene, normal butene, isobutene, etc.] and alkaziene having 2 to 10 carbon atoms [for example, butadiene, isoprene, etc.] Esterization reaction and amide of a hydroxyl group-containing (co) polymer having a hydroxyl group introduced at one end or an amino group-containing (co) polymer having an amino group introduced at one end of a hydrocarbon polymer and (meth) acrylic acid. Chemical reaction, or ester exchange reaction with methyl (meth) acrylate, (co) polymer with a carboxyl group or acid anhydride group introduced at one end of the hydrocarbon polymer, and (meth) acrylic acid having a hydroxyl group. , A monomer obtained by an addition reaction between a (co) polymer having an epoxy group introduced at one end of a hydrocarbon polymer and (meth) acrylic acid, and the number average molecular weight is preferably 1000 to 15000}. , Monoesteride of alicyclic alcohol having 3 to 20 carbon atoms and (meth) acrylic acid {glycidyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, Bornil (meth) ) Acrylic and isobornyl (meth) acrylate}, tetrahydrofurfuryl (meth) acrylate and the like.

In the present invention, the weight ratio of the cyclizable polymerizable monomer (a1) in the monomer constituting the (meth) acrylic polymer (A) is 1 to 20% by weight from the viewpoint of adhesiveness and coatability. Yes, preferably 5-10% by weight. If it is less than 1% by weight, the adhesiveness tends to be inferior, and if it exceeds 20% by weight, the coatability tends to be inferior.
The weight ratio of the alkyl (meth) acrylate (a2) in the monomer constituting the (meth) acrylic polymer (A) is preferably 80 to 99% by weight, more preferably from the viewpoint of adhesiveness and coatability. Is 80 to 98% by weight, particularly preferably 90 to 95% by weight, and most preferably 90 to 94% by weight.

The weight ratio of the monomer (a3) in the monomer constituting the (meth) acrylic polymer (A) is preferably 0.5% by weight or less from the viewpoint of suppressing thickening under high temperature conditions, and further. It is preferably 0.1% by weight or less.
The weight ratio of the monomer (a4) in the monomer constituting the (meth) acrylic polymer (A) is 0.5% by weight or less from the viewpoint of corrosiveness and suppression of thickening under high temperature conditions. It is preferable, more preferably 0.1% by weight or less.
The weight ratio of the monomer (a5) in the monomer constituting the (meth) acrylic polymer (A) is 0.5% by weight from the viewpoint of making it difficult to color the (meth) acrylic polymer (A). The following is preferable, and more preferably 0.1% by weight or less.
From the viewpoint of adhesiveness, the weight ratio of the monomer (a6) in the monomer constituting the (meth) acrylic polymer (A) is preferably 30% by weight or less, more preferably 20% by weight or less. ..
The weight ratio {(a1) / (a2)} of the cyclized polymerizable monomer (a1) and the alkyl (meth) acrylate (a2) in the monomer constituting the (meth) acrylic polymer (A) is adhesive. From the viewpoint of property and coatability, 0.01 to 0.3 is preferable, and 0.05 to 0.2 is more preferable.

In the present invention, the (meth) acrylic polymer (A) is a known polymerization initiator (azo) by using a known polymerization method (lump polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc.) for the monomer component. Use an azo-based polymerization initiator such as bisisobutyronitrile or azobisisovaleronitrile; a peroxide-based polymerization initiator such as benzoyl peroxide, dit-butyl peroxide, or lauryl peroxide). Can be done.
Of the above polymerization methods, a method of solution polymerization in the presence of a solvent (S) (for example, ethyl acetate) is preferable.

In the present invention, the weight average molecular weight of the (meth) acrylic polymer (A) by gel permeation chromatography (GPC) is 100,000 to 500,000, preferably 200,000 to 400,000.
When the weight average molecular weight is 100,000 or more, the adhesiveness tends to be good, and when the weight average molecular weight is 500,000 or less, the coatability tends to be good.

The measurement conditions of gel permeation chromatography (GPC) of the (meth) acrylic polymer (A) in the present invention are as follows.
Equipment: "HLC-8120GPC" [manufactured by Tosoh Corporation]
Column: "Guardcolumn HXL-H" (1),
"TSKgel GMHXL" (2 bottles) [both manufactured by Tosoh Corporation]
Sample solution: 0.25 wt% tetrahydrofuran solution Injection amount: 100 μl
Flow rate: 1 ml / min Measurement temperature: 40 ° C
Detector: Refractive index detector Reference material: Standard polystyrene

In the present invention, the acid value of the (meth) acrylic polymer (A) is 4 mgKOH / g or less, preferably 0.8 mgKOH / g or less, and more preferably 0 mgKOH / g.
When the acid value exceeds 4 mgKOH / g, the corrosiveness tends to be high, the thickening tends to proceed under high temperature conditions, and the coatability tends to be poor.
The acid value can be measured according to JIS K0070.

In the present invention, the hydroxyl value of the (meth) acrylic polymer (A) is 3 mgKOH / g or less, preferably 0.6 mgKOH / g or less, and more preferably 0 mgKOH / g.
When the hydroxyl value exceeds 3 mgKOH / g, thickening tends to proceed under high temperature conditions, and the coatability tends to be poor.
The hydroxyl value can be measured according to JIS K0070.

In the present invention, the solubility parameter (SP value) of the (meth) acrylic polymer (A) is preferably 9.2 to 9.9 (cal / cm ³ ) ^1/2 from the viewpoint of adhesiveness, and more preferably. Is 9.5 to 9.8 (cal / cm ³ ) ^1/2 .
The SP value is an abbreviation for solubility parameter and is a measure of solubility. The SP value is a value indicating that the larger the value is, the higher the polarity is, and conversely, the smaller the value is, the lower the polarity is. It is a value at 25 ° C. calculated by the above method.
The SP value of the polymer (A) is determined by calculating the average value based on the solid content weight ratio in the monomer constituting the polymer (A) using the SP value of each monomer. Can be done. For the cyclizable polymerizable monomer (a1), the SP value is calculated based on the structure after cyclization.
The SP value of the polymer (A) can be adjusted depending on the type and amount of the monomer used. Specifically, it can be reduced by using a large number of alkyl groups having a long carbon number, and can be increased by using a large number of alkyl groups having a short carbon number or a large proportion of polar groups or the like. ..

<Polyfunctional (meth) acrylic monomer (B)>
The polyfunctional (meth) acrylic monomer (B) in the present invention has two or more (meth) acryloyl groups in the molecule, and preferably has 2 to 6 (meth) acryloyl groups from the viewpoint of adhesiveness. Those having 3 to 4 (meth) acryloyl groups are more preferable.
In (B), one type may be used, or two or more types may be used in combination.

The polyfunctional (meth) acrylic monomer (B) includes a bifunctional (meth) acrylic monomer (B1), a trifunctional (meth) acrylic monomer (B2), a tetrafunctional (meth) acrylic monomer (B3), and a pentafunctional or higher functional (B3). Meta) Acrylic monomer (B4) and the like can be mentioned.

The bifunctional (meth) acrylic monomer (B1) has a structure in which 1 mol of a compound having two or more hydroxyl groups having 2 to 20 carbon atoms and 2 mol of (meth) acrylic acid are esterified;
A compound having an esterification structure of 1 mol of an alkylene oxide addition and 2 mol of (meth) acrylic acid to a compound having two or more hydroxyl groups having 2 to 20 carbon atoms; and two or more carbon atoms having 2 to 20 carbon atoms. Examples thereof include those having a structure in which 1 mol of a lactone addition to a compound having a hydroxyl group and 2 mol of (meth) acrylic acid are esterified.

Examples of the compound having two or more hydroxyl groups having 2 to 20 carbon atoms include a chain aliphatic alcohol having 2 to 20 carbon atoms, an alicyclic alcohol having 3 to 20 carbon atoms, and an aromatic compound having 6 to 15 carbon atoms. Examples thereof include a sex hydroxylated compound.
Examples of the chain aliphatic alcohol having 2 to 20 carbon atoms include chain aliphatic dihydric alcohols having 2 to 20 carbon atoms [ethylene glycol, 1,2- or 1,3-propylene glycol, 1,2-butanediol, and the like. 1,4-Butanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, dodecanediol, tetradecanediol, neopentyl glycol and 2,2-diethyl-1,3-propanediol Etc.], chain aliphatic trihydric alcohols having 3 to 20 carbon atoms [glycerin, trimethylolethane and trimethylolpropane, etc.]; and chain aliphatic 4 to 8 valent alcohols having 5 to 20 carbon atoms [pentaerythritol, ditri]. Methylolpropane, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol, etc.] and the like.
Examples of the alicyclic alcohol having 3 to 20 carbon atoms include dihydric alcohols [1,3-cyclopentanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-cycloheptanediol, 2, 2-Bis (4-hydroxycyclohexyl) propane and the like], trihydric alcohols [1,3,5-cyclohexanetriol and the like] and the like can be mentioned.
Examples of the aromatic hydroxyl group-containing compound having 6 to 15 carbon atoms include pyrogallol, catechol, resorcinol, hydroquinone, dihydroxynaphthalene, bisphenol A, bisphenol F, bisphenol S, and 1,3,5-triazine-2,4,6-. Triol and the like can be mentioned.

Examples of the alkylene oxide include alkylene oxides having 2 to 4 carbon atoms, and specific examples thereof include ethylene oxide (hereinafter, “ethylene oxide” may be abbreviated as EO), 1,2-. Or 1,3-propylene oxide (hereinafter, "1,2-propylene oxide" may be abbreviated as PO) and 1,2-, 1,3-, 1,4- or 2,3-butylene oxide, etc. Can be mentioned.
As the alkylene oxide, EO and PO are preferable, and PO is more preferable, from the viewpoint of adhesiveness.
The number of moles of alkylene oxide added per molecule is preferably 1 to 40 mol.

Examples of the lactone include lactones having 2 to 12 carbon atoms, and specific examples thereof include acetolactone, propiolactone, butyrolactone, valerolactone, caprolactone and laurolactone.
The number of moles of lactone added per molecule is preferably 1 to 15 mol.

Specific examples of the bifunctional (meth) acrylic monomer (B1) include 1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, and neopentyl glycol di (meth) acrylate. 2,4-dimethyl-1,5-pentanediol di (meth) acrylate, butylethylpropanediol di (meth) acrylate, di (meth) acrylate of alkylene oxide adduct having 2 to 4 carbon atoms of cyclohexanemethanol, polypropylene glycol Di (meth) acrylate, polyethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, 2-ethyl-2-butyl-butanediol di (meth) acrylate, addition of alkylene oxide having 2 to 4 carbon atoms of bisphenol A. Di (meth) acrylate of bisphenol F, di (meth) acrylate of alkylene oxide adduct having 2 to 4 carbon atoms, 1,4-butanediol di (meth) acrylate, 2-ethyl-2-butyl-propanediol Examples thereof include di (meth) acrylate and 1,9-nonanediol di (meth) acrylate.

As the trifunctional (meth) acrylic monomer (B2),
Among the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of the compound having 3 or more hydroxyl groups and 3 mol of (meth) acrylic acid;
Of the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of an alkylene oxide addition and 3 mol of (meth) acrylic acid to the compound having three or more hydroxyl groups; and the carbon. Among the compounds having two or more hydroxyl groups of the number 2 to 20, an esterified product of 1 mol of a lactone adduct to a compound having 3 or more hydroxyl groups and 3 mol of (meth) acrylic acid can be mentioned.
The preferred number of moles of the alkylene oxide and the alkylene oxide and the number of moles of the lactone and the lactone are the same as in (B1) above.

Specific examples of the trifunctional (meth) acrylic monomer (B2) include trimethylol ethanetri (meth) acrylate, trimethylol propanetri (meth) acrylate, and alkylene oxide adduct having 2 to 4 carbon atoms of trimethylol propane. Tri (meth) acrylate, glycerin tri (meth) acrylate, tri (meth) acrylate of alkylene oxide adduct with 2 to 4 carbon atoms of glycerin, pentaerythritol tri (meth) acrylate, alkylene with 2 to 4 carbon atoms of pentaerythritol. Tri (meth) acrylate of oxide adduct, dipentaerythritol tri (meth) acrylate, tri (meth) acrylate of alkylene oxide adduct having 2 to 4 carbon atoms of dipentaerythritol, sorbitol tri (meth) acrylate , Tri (meth) acrylate of an alkylene oxide adduct having 2 to 4 carbon atoms of sorbitol and the like.

As the above-mentioned tetrafunctional or higher (meth) acrylic monomer (B3),
Among the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of the compound having 4 or more hydroxyl groups and 4 mol or more of (meth) acrylic acid;
Among the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of an alkylene oxide addition and 4 mol or more of (meth) acrylic acid to the compound having 4 or more hydroxyl groups; Among the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of a lactone adduct to a compound having 4 or more hydroxyl groups and 4 mol or more of (meth) acrylic acid can be mentioned.
The preferred number of moles of the alkylene oxide and the alkylene oxide and the number of moles of the lactone and the lactone are the same as in (B1) above.

Specific examples of the tetrafunctional (meth) acrylic monomer (B3) include pentaerythritol tetra (meth) acrylate, tetra (meth) acrylate of an alkylene oxide adduct having 2 to 4 carbon atoms of pentaerythritol, and sorbitol tetra (meth). Tetra (meth) acrylate of alkylene oxide adduct having 2 to 4 carbon atoms of acrylate and sorbitol, tetra (meth) acrylate of alkylene oxide adduct of ditrimethylol propanetetra (meth) acrylate and ditrimethylol propane having 2 to 4 carbon atoms. , Dipentaerythritol tetra (meth) acrylate, tetra (meth) acrylate of an alkylene oxide adduct having 2 to 4 carbon atoms of dipentaerythritol and the like.

As the above-mentioned 5-functional or higher (meth) acrylic monomer (B4),
Among the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of the compound having 5 or more hydroxyl groups and 5 mol or more of (meth) acrylic acid;
Of the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of an alkylene oxide addition and 5 mol or more of (meth) acrylic acid to the compound having 5 or more hydroxyl groups; and the above. Among the compounds having two or more hydroxyl groups having 2 to 20 carbon atoms, an esterified product of 1 mol of a lactone adduct to a compound having 5 or more hydroxyl groups and 5 mol or more of (meth) acrylic acid can be mentioned.
The preferred number of moles of the alkylene oxide and the alkylene oxide and the number of moles of the lactone and the lactone are the same as in (B1) above.

Specific examples of the pentafunctional or higher (meth) acrylic monomer (B4) include sorbitol penta (meth) acrylate, penta (meth) acrylate of an alkylene oxide adduct having 2 to 4 carbon atoms of sorbitol, and dipentaerythritol penta (meth). ) Penta (meth) acrylate of acrylate, alkylene oxide adduct having 2 to 4 carbon atoms of dipentaerythritol, hexa (meth) acrylate of alkylene oxide adduct of dipentaerythritol hexa (meth) acrylate, hexa (meth) acrylate of alkylene oxide adduct of dipentaerythritol having 2 to 4 carbon atoms. Examples thereof include meth) acrylate, sorbitol hexa (meth) acrylate, hexa (meth) acrylate of an alkylene oxide adduct having 2 to 4 carbon atoms of sorbitol, and caprolactone-modified dipentaerythritol hexa (meth) acrylate.

The polyfunctional (meth) acrylic monomer (B) is a bird of an alkylene oxide adduct having 2 to 4 carbon atoms of a compound having 3 or more hydroxyl groups having 2 to 20 carbon atoms from the viewpoint of adhesiveness and workability. Tetra, penta or hexa (meth) acrylates are preferred, and more preferably tri or tetra (meth) acrylates of alkylene oxide adducts having 2 to 4 carbon atoms of compounds having 3 or more hydroxyl groups having 2 to 20 carbon atoms. Next, more preferably, the tri (meth) acrylate of the alkylene oxide adduct having 2 to 4 carbon atoms of trimethylolpropane, the tri (meth) acrylate of the alkylene oxide adduct of the alkylene oxide adduct having 2 to 4 carbon atoms of pentaerythritol, and pentaerythritol. It is a tetra (meth) acrylate of an alkylene oxide adduct having 2 to 4 carbon atoms, and particularly preferably a tri (meth) acrylate of an alkylene oxide adduct having 2 to 4 carbon atoms of trimethylolpropane.

The chemical formula amount or number average molecular weight of the polyfunctional (meth) acrylic monomer (B) is preferably 250 to 600, more preferably 350 to 550, from the viewpoint of adhesiveness.

The measurement conditions for gel permeation chromatography (GPC) of the polyfunctional (meth) acrylic monomer (B) in the present invention are as follows.
Equipment: "Waters Alliance 2695" [manufactured by Waters]
Column: "Guardcolum Super HL" (1 bottle) and "TSKgel SuperH2000, TSKgel SuperH3000, TSKgel SuperH4000 (all manufactured by Tosoh Corporation) 1 bottle each" sample solution: 0.25 wt% tetrahydrofuran solution Solution injection volume: 10 μl
Flow rate: 0.6 ml / min Measurement temperature: 40 ° C
Detector: Refractive index detector Reference material: Standard polyethylene glycol

The molecular weight (chemical formula amount or number average molecular weight / number of (meth) acryloyl groups) per (meth) acryloyl group of the polyfunctional (meth) acrylic monomer (B) is preferably 100 to 300 from the viewpoint of adhesiveness. , More preferably 120-200.

<Photopolymerization initiator (C)>
The photopolymerization initiator initiates the polymerization of the polyfunctional (meth) acrylic monomer (B) by irradiation with active energy rays. Here, the "active energy ray" means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include ultraviolet rays, electron beams, visible rays, X-rays, and ion beams. Among them, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable, from the viewpoint of versatility.

The photopolymerization initiator (C) is not particularly limited, and is, for example, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl-phenylketone, 2-hydroxy-2-methyl-1-henylpropanol, 1-[. 4- (2-Hydroxyethoxyl) -phenyl] -2-hydroxy-methylpropanol, 2-hydroxy-1- (4- (4- (2-hydroxy-2-methylpropionyl) benzyl) phenyl) -2-methyl Acetphenone-based photopolymerization initiators such as -1-propanone, acylphosphine oxide-based photopolymerization such as 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and 2,4,6-trimethylbenzoyl) phenylphosphine oxide. Examples thereof include an initiator, a hydrogen abstraction type photopolymerization initiator such as methyl benzoylrate and 4-methylbenzophenone, and an oil-soluble polymerization initiator such as an oxime ester-based photopolymerization initiator and a cationic photopolymerization initiator.
The photopolymerization initiator (C) is preferably a hydrogen abstraction type photopolymerization initiator from the viewpoint of adhesiveness. The hydrogen abstraction type photopolymerization initiator can initiate a cross-linking reaction by generating radicals by abstracting hydrogen from another molecule such as the polymer (A).

Commercially available products of such a hydrogen abstraction type photopolymerization initiator include Omnirad MBF (former Irgacure MBF) (methyl benzoyl formate, IGM Resins B.V. photoinitiator), SB-PI 701 (4,4'-bis). (Diethylamino) benzophenone, Sanyo Trading Co., Ltd. photoinitiator), SB-PI 710 (benzophenone, Sanyo Trading Co., Ltd. photoinitiator), SB-PI 712 (4-methylbenzophenone, Sanyo Trading Co., Ltd. photoinitiator) ) Etc. can be mentioned.

The content of the (meth) acrylic polymer (A) in the photocurable pressure-sensitive adhesive composition is 84.0 or more based on the weight of the photo-curable pressure-sensitive adhesive composition from the viewpoint of tackiness and coatability. It is preferably 99.9% by weight, more preferably 89.0 to 99.8% by weight.
The content of the polyfunctional (meth) acrylic monomer (B) in the photocurable pressure-sensitive adhesive composition is 0.05 to 15.0 based on the weight of the photo-curable pressure-sensitive adhesive composition from the viewpoint of adhesiveness. The weight is preferably%, more preferably 0.1 to 10.0% by weight.
The content of the photopolymerization initiator (C) in the photocurable pressure-sensitive adhesive composition is 0.05 to 1.5% by weight based on the weight of the photo-curable pressure-sensitive adhesive composition from the viewpoint of adhesiveness. It is preferable, more preferably 0.1 to 1.0% by weight.
The weight ratio {(A) / (B)} of the (meth) acrylic polymer (A) and the polyfunctional (meth) acrylic monomer (B) in the photocurable adhesive composition is from the viewpoint of adhesiveness. It is preferably 5 to 2000, more preferably 8.5 to 1000, and particularly preferably 100 to 300.

The photocurable pressure-sensitive adhesive composition of the present invention may contain a known cross-linking agent such as an isocyanate compound, an epoxy compound, an oxazoline compound, an aziridine compound, a metal chelate compound, and a butylated melamine compound.
Examples of the isocyanate compound include aromatic polyisocyanates (for example, tolylene diisocyanate, xylylene diisocyanate, etc.), aliphatic polyisocyanates (hexamethylene diisocyanate, isophorone diisocyanate, etc.) and the like. Examples of commercially available products include tolylene diisocyanate compounds (manufactured by Tosoh Corporation, Coronate L), xylylene diisocyanate compounds (manufactured by Mitsui Chemicals, Inc., Takenate D-110N) and the like. Examples of the epoxy compound include TETRAD-C (manufactured by Mitsubishi Gas Chemical Company, Inc.), TETRAD-X manufactured by Mitsubishi Gas Chemical Company, Inc.) and the like. Examples of the metal chelate compound include aluminum chelate A (manufactured by Kawaken Fine Chemicals Co., Ltd.).
The content of the cross-linking agent in the photocurable pressure-sensitive adhesive composition is preferably 0.05 to 5.0% by weight, more preferably 0.1 to 1.0% by weight, from the viewpoint of tackiness.

The photocurable pressure-sensitive adhesive composition may contain a solvent. In this case, the solvent is used to improve the coatability of the photocurable pressure-sensitive adhesive composition. Examples of the solvent include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene and dichloropropane; methanol, ethanol, Alcohols such as propanol, isopropyl alcohol, butanol, isobutyl alcohol and diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane and tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone and cyclohexanone; methyl acetate , Ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate and other esters; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene. Examples thereof include polyols such as glycol monomethyl ether acetate and derivatives thereof.

<Other ingredients>
The photocurable pressure-sensitive adhesive composition may contain components other than the above as long as the effects of the present invention are not impaired. Examples of other components include components known as additives for adhesives. For example, a plasticizer, an antioxidant, a metal corrosion inhibitor, a silane coupling agent, an ultraviolet absorber, a light stabilizer such as a hindered amine compound, and the like can be selected as needed. Further, dyes and pigments may be added for the purpose of coloring.

As the plasticizer, for example, a non-functional group acrylic polymer may be used. The non-functional group acrylic polymer does not have a polymer consisting of only an acrylic monomer unit having no functional group other than an acrylate group, or an acrylic monomer unit having no functional group other than an acrylate group and no functional group. A polymer composed of a non-acrylic monomer unit can be mentioned. Since the non-functional group acrylic polymer does not crosslink, it is possible to improve the step followability when the non-functional group acrylic polymer is attached to the adherend without affecting the adhesiveness.
Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, lactone-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and the like. One type of these antioxidants may be used alone, or two or more types may be used in combination.
As the metal corrosion inhibitor, a benzotriazole-based resin can be mentioned as a preferable example because of the compatibility and high effect of the pressure-sensitive adhesive.
Examples of the silane coupling agent include a mercaptoalkoxysilane compound (for example, a mercapto group-substituted alkoxy oligomer), (meth) acryloxypropylmethoxysilane, and the like.
Examples of the ultraviolet absorber include benzotriazole-based compounds, benzophenone-based compounds, and triazine-based compounds.

The photocurable pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic polymer (A), a polyfunctional (meth) acrylic monomer (B), a photopolymerization initiator (C), and various additives as necessary. It can be manufactured by uniformly mixing in a mixing tank equipped with a stirrer, a static mixer, etc.).

The photocurable pressure-sensitive adhesive composition of the present invention is directly applied to at least a part of at least one side of a base material using various coating devices and cured by active energy rays (UV, electron beam, etc.). Can be used. The photocurable pressure-sensitive adhesive composition of the present invention can be formed into a desired shape by melting by heating, and is rapidly cured by irradiating a high-energy ray such as ultraviolet rays while maintaining the shape. There is a feature.
A preferred form of use is a form in which the photocurable pressure-sensitive adhesive composition is heated to 130 to 180 ° C., applied, and cured with active energy rays. That is, the photocurable pressure-sensitive adhesive composition of the present invention can be said to be an active energy ray-curable hot-melt pressure-sensitive adhesive composition.

Since the photocurable pressure-sensitive adhesive composition of the present invention has good adhesive properties and coatability, it is used for packaging (packaging of frozen foods, binding of vegetables, etc.) and marking (automobile moldings, emblems, etc.). It can be suitably used for various purposes such as (mark, etc.), masking (glass sealing, architectural curing, etc.), surface protection (painted surface protection, etc.), medical use (adhesive plaster, etc.) and office use. It is particularly useful as an adhesive for displays and / or optical members because it has less corrosion, good adhesive properties, and high stability under high temperature conditions.
Examples of the optical member include each constituent member in an optical product such as a touch panel and a display. As the constituent members of the touch panel, for example, an ITO film having an ITO (indium tin oxide) film provided on a transparent resin film, ITO glass having an ITO film provided on the surface of a glass plate, and a transparent resin film coated with a conductive polymer. Examples thereof include a transparent conductive film, a hard coat film, and a fingerprint resistant film. Examples of the constituent members of the display include an antireflection film, an alignment film, a polarizing film, a retardation film, and a luminance improving film used in a liquid crystal display device.

<Adhesive film>
The pressure-sensitive adhesive film of the present invention has a pressure-sensitive adhesive layer formed from the photocurable pressure-sensitive adhesive composition of the present invention on at least one surface of a base material.

The base material includes films, sheets, foams and flat yarns of various plastics [polyethylene (polyethylene and polypropylene, etc.), polyurethane, polyethylene terephthalate, polyvinyl chloride, rayon, polyamide, etc.], paper (Japanese paper, crepe paper, etc.), and metals. Examples include boards, metal foils, woven fabrics, non-woven fabrics and wood.

The thickness of the pressure-sensitive adhesive layer is preferably 10 to 200 μm, more preferably 30 to 100 μm, from the viewpoint of adhesiveness and coatability.

The pressure-sensitive adhesive layer is a photo-curable pressure-sensitive adhesive composition, for example, a coating device (blade coater, air knife coater, roll coater, bar coater, gravure coater, micro gravure coater, rod blade coater, lip coater, die coater, curtain. It can be formed by applying using a coater or the like).

Since the pressure-sensitive adhesive composition of the present invention is difficult to thicken or gel even under high temperature conditions and has high stability, when forming the pressure-sensitive adhesive layer, for example, the temperature of the pressure-sensitive adhesive composition is preferably 130 to 180 ° C. May be applied.

The photocurable pressure-sensitive adhesive composition of the present invention is photocured by irradiating it with active energy rays.
The active energy ray may be selected according to the type of the photopolymerization initiator (C).
The light source is not particularly limited as long as the photopolymerization initiator (C) contained in the photocurable pressure-sensitive adhesive composition can irradiate light in a sensitive wavelength range, and is an LED light source, a high-pressure mercury lamp, and an ultrahigh pressure. Mercury lamps, metal halide lamps, xenon lamps and the like are preferably used.
The integrated light amount of the irradiation light is preferably 100 to 10000 mJ / cm ² , more preferably 500 to 5000 mJ / cm ² .
In the step of irradiating the coating film with the active energy ray, the active energy ray may be irradiated in two steps. For example, the irradiation intensity of the second stage can be increased as compared with the first stage. By performing such two-step irradiation, it becomes easy to adjust the molecular weight of the obtained photocurable pressure-sensitive adhesive composition due to the curing reaction, and it is possible to suppress heat shrinkage and the like.

The adhesive film of the present invention is particularly useful as an adhesive film for displays and / or optical members because it causes less corrosion of metal members and has good adhesive properties and coatability.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following, the part represents the weight part.

Synthesis Example 1 [Synthesis of α-allyloxymethylacrylate ethyl]
In a 5L four-necked flask equipped with a stirrer, a cooling tube, a thermometer, a gas blowing tube, and a decompression device, 2199.4 parts of ethyl α- (hydroxymethyl) acrylate, and 1,4-diazabicyclo as a catalyst [2. 2,2] Octane 98.9 parts, p-methoxyphenol (MEHQ) 1.02 parts as a polymerization inhibitor, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4H-TEMPO) I prepared 1.02 copies. Then, while blowing an oxygen / nitrogen mixed gas (oxygen concentration 8%), the temperature of the reaction solution was raised to 100 ° C. under a reduced pressure of 10 kPa, and the reaction was carried out for 2 hours while distilling off the generated water. After depressurizing, a solution prepared by dissolving 98.0 parts of 1,4-diazabicyclo [2,2,2] octane in 1523.0 parts of allyl alcohol at 100 ° C. under normal pressure was added dropwise over 2 hours, and further 12 hours. It was reacted. After the reaction, the yield of ethyl α-allyloxymethyl acrylate was 59 mol% with respect to α- (hydroxymethyl) ethyl, and the conversion rate of α- (hydroxy) ethyl acrylate was measured by gas chromatography. It was 89 mol%. Next, the remaining allyl alcohol was distilled off under reduced pressure (operating pressure: 7 kPa) by simple distillation to obtain 2778.1 parts of the reaction solution. 919.5 parts of 8 mass% sodium hydroxide solution was added to this reaction solution, and the mixture was stirred at room temperature for 30 minutes and then allowed to stand for 30 minutes, and separated into oil and water to obtain 2101.3 parts of an organic phase. Further, 231.3 parts of an 8 mass% sodium hydroxide solution was added to this organic phase, and the mixture was stirred at room temperature for 30 minutes and then allowed to stand for 30 minutes, and then separated by oil and water to obtain 177.7 parts of an organic phase. Subsequently, the obtained organic phase was washed with a 5% by mass aqueous solution of Glauber's salt to separate oil and water. After repeating this operation, 1900.7 parts of an organic phase was obtained. To this organic phase, 0.95 parts of MEHQ, 0.95 parts of 2-t-butylhydroquinone (TBH), and 0.95 parts of triphenyl phosphite were added as polymerization inhibitors, and an oxygen / nitrogen mixed gas (oxygen concentration 8%) was added. Distilled using a packing column filled with Dixon packing under a reduced pressure of 2 kPa to obtain 1337.3 parts of ethyl α-allyloxymethylacrylate having a purity of 99.5% by mass.

Production Example 1 [Production of (meth) acrylic polymer (A-1)]
84 parts of ethyl acetate as a solvent was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen gas introduction tube, and the temperature was raised. Under reflux with a solvent, 10 parts of methyl α-allyloxymethyl acrylate and 90 parts of n-butyl acrylate are mixed with a monomer compounding solution, and 2,2'-azobis (2,4-dimethylvaleronitrile) 0.18 part is acetic acid. Radical polymerization was carried out by continuously dropping the <initiator solution 1> dissolved in 16 parts of ethyl over 6 hours using a dropping funnel while blowing nitrogen into the reaction vessel.
After completion of the dropping, the initiator solution 2 in which 0.24 parts of 2,2'-azobis (2,4-dimethylvaleronitrile) was dissolved in 16 parts of ethyl acetate was added dropwise to the funnel under stirring at the same temperature. It was added continuously over 1 hour using. Then, the mixture was heated to 130 ° C. under reduced pressure to distill off ethyl acetate. Then, the mixture was filtered through an industrial woven wire mesh (JIS G3556) having an opening of 0.196 mm at 130 ° C. and a back pressure of 0.5 MPa to obtain a (meth) acrylic polymer (A-1). Table 1 shows the results of Mw, hydroxyl value, acid value, heat resistance test, coloring test and melt viscosity of (A-1).

<Production Examples 2 to 22 and Comparative Production Examples 1 to 5>
In Production Example 1, a (meth) acrylic polymer (A) and a comparative (meth) acrylic polymer (A') were obtained in the same manner as in Production Example 1 except that the raw materials shown in Table 1 were used. The results of the Mw, hydroxyl value, acid value, heat resistance test and coloring test of the obtained (meth) acrylic polymer (A) or (A') are shown in Table 1 or 2.

<Heat resistance test>
The (meth) acrylic polymer (A) or (A') was allowed to stand at 150 ° C. under reduced pressure conditions (gauge pressure -100 kPa) for 7 hours, and then the weight average molecular weight was measured by gel permeation chromatography. The rate of change from the molecular weight before placement was calculated by the following formula and evaluated according to the following criteria.

Rate of change (%) = Mw (after heat resistance test) / Mw (before heat resistance test) x 100

<Evaluation criteria>
⊚: Change rate is 100% or more and less than 105% ○: Change rate is 105% or more and less than 110% Δ: Change rate is 110% or more and less than 120% ×: Change rate is 120% or more

<Coloring test>
By sandwiching 1.5 g of the (meth) acrylic polymer (A) or (A') between two 50 μm polyester films [“Lumilar” type T manufactured by Toray Industries, Inc.] and heating and pressing at 100 ° C. The thickness of the (meth) acrylic polymer (A) or (A') was adjusted to 100 μm. The color difference (b *) of the obtained test piece was measured and evaluated according to the following criteria. The color difference was measured using a color difference meter (“NDH-300A” manufactured by Nippon Denshoku Kogyo Co., Ltd.).
○: Less than 0.7 ×: 0.7 or more

<Evaluation method of melt viscosity>
The melt viscosity at 130 ° C. was measured according to JIS K7117-1: 1999 (RB viscosity type viscometer, RB6 spindle rotation speed 2 rpm condition).

In addition, in Tables 1 and 2, the following was used for each component.
α-allyloxymethyl Methyl acrylate: manufactured by Nippon Shokubai Co., Ltd., trade name "AOMA"
α-Allyloxymethylacrylate Ethyl acrylate: Obtained in Synthesis Example 1 Hydrogenated polybutadiene methacrylate: Methacrylic-modified polybutadiene (“L1253” (Mn = 7000) manufactured by Kuraray Co., Ltd.)

<Examples 1 to 26 and Comparative Examples 1 to 5>
The (meth) acrylic polymer (A) or (A'), the polyfunctional (meth) acrylic monomer (B), and the photopolymerization initiator (C) are blended with a Henshell mixer for 3 minutes according to Tables 3 to 4. , Each photocurable pressure-sensitive adhesive composition (Q) or (Q') was obtained by melt-kneading in a twin-screw extruder with a vent under the conditions of 150 ° C., 100 rpm and a residence time of 3 minutes.

Tables 3 to 4 show the evaluation results of the coatability, adhesiveness, and corrosiveness of the photocurable pressure-sensitive adhesive composition (Q) or (Q').

The photocurable pressure-sensitive adhesive composition (Q) or (Q') was evaluated by the following method.

<Evaluation method of coatability>
The photocurable pressure-sensitive adhesive composition (Q) or (Q') is melted at 150 ° C., and at an environmental temperature of 23 ° C., a polyester decorative sheet base material [“Lumilar” type T manufactured by Toray Industries, Inc.: Length. 10 cm, width 2.5 cm, thickness 200 μm] Apply on the surface with a coating amount of 60 g / m ² using a slot coater, and after 1 minute, polyester decorative sheet base material [Toray Industries, Inc.] "Lumirror" type T: length 10 cm, width 2.5 cm, thickness 200 μm] is combined, and a rubber roller with a load of 2 kg is used to reciprocate once at a speed of 300 mm / min to bond the test pieces. Made. The appearance of the obtained test piece was visually observed and evaluated according to the following criteria.
<Evaluation criteria>
⊚: No defects such as interference fringes and pinholes on the appearance.
◯: Although there are some interference fringes on the appearance, there are no defects such as pinholes.
X: There is a defect such as a pinhole in the appearance.

<Measurement of adhesiveness>
(1) Preparation of Adhesive Film A photocurable adhesive composition (Q) or (Q') is melted at 150 ° C., and a 25 μm polyester film [“Lumilar” manufactured by Toray Industries, Inc. Type T, PET] The surface is coated with a coating amount of 30 g / m ² using a slot coater, and a UV irradiation device [Ushio Denki Co., Ltd., "UVC-02516S1AA01"] is used as a light source: metal halide lamp, A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer having a thickness of 30 μm was prepared by irradiating with 1000 mJ / cm ² at 2.
(2) Measurement of Adhesiveness Using the adhesive film test piece [vertical 100 mm x horizontal 25 mm] cut out from the adhesive film obtained in (1) above, JIS-Z-0237; 2009 "Adhesive Tape, Adhesive Sheet Test Method" Based on this, the adhesive film and the SUS304 / BA plate [width 100 mm, length 150 mm, thickness 0.6] were bonded together in an atmosphere of 25 ° C. with one reciprocation of a 2 kg roller. After the bonding, the mixture was further left at 23 ° C. for 1 day, and the 180 ° peel strength at 23 ° C. was measured (25 mm width, tensile speed 300 mm / min). When it is 10 N / 25 mm or more, it means that the adhesiveness is particularly good and the adhesive film is hard to be peeled off from the base material. In the case of cohesive failure, when the adhesive is peeled off from the base material such as a protective film and used, or when electronic devices using the adhesive film are discarded or reused, the adhesive destroyed on the base material remains and is washed. Not preferable because it is necessary.

<Corrosion test>
Using the adhesive film test piece [vertical 100 mm x horizontal 25 mm] cut out from the adhesive film obtained in (1) above, the adhesive film and ITO layer are based on JIS-Z-0237; 2009 "Adhesive Tape, Adhesive Sheet Test Method". A PET film having the above [thickness 0.18 mm, the same applies hereinafter] was bonded to each other in an atmosphere of 25 ° C. with one reciprocation of a 2 kg roller to obtain a laminated film. Then, after leaving it for 14 days under the condition of 25 ° C. × 90% relative humidity RH, the resistance value (R ₁ ) of the PET film having the ITO layer peeled off at 180 ° was measured, and the resistance change rate was calculated by the following formula. (%) Was calculated. Note that R ₀ indicates the resistance value (Ω) before bonding. The smaller the rate of change in resistance value, the smaller the corrosiveness and the better, and if it is 4% or less, it can be said that there is no problem in practical use.
Resistance value change rate (%) = (R ₁ -R ₀ ) / R ₀ × 100

In addition, in Tables 3 and 4, the following was used for each component.
Neomer TA-505: Triacrylate, Mn = 460, PO adduct of trimethylolpropane, manufactured by Sanyo Chemical Industries, Ltd.
Neomer TA-401: Triacrylate, Mn = 405, EO adduct of trimethylolpropane, manufactured by Sanyo Chemical Industries, Ltd.
Neomer DA-600: manufactured by Sanyo Chemical Industries, Ltd., dipentaerythritol pentaacrylate, Mn = 540
4-Methylbenzophenone: manufactured by Sanyo Trading Co., Ltd., trade name "SB-PI 712"

From the results in Tables 1 and 2, the (meth) acrylic polymer (A) contained in the photocurable pressure-sensitive adhesive composition of the present invention does not easily change in molecular weight when left to stand for a certain period of time under high temperature conditions, and has heat resistance. It turns out to be expensive. Further, since the melt viscosity is low, the coating property is excellent, the coating temperature can be reduced, and thickening and suppression of gelation can be expected. Further, from the results of Tables 3 to 4, it can be seen that the photocurable pressure-sensitive adhesive composition of the present invention is less corrosive to the metal member, has excellent adhesive properties, and is excellent in coatability.
On the other hand, in Example 7, a (meth) acrylic polymer (A) in which a part of the cyclization polymerizable monomer (a1) was changed to a monomer having a carboxyl group or a hydroxyl group and the acid value or the hydroxyl value was out of the numerical range. It can be seen that in'-1) to (A'-3), the rate of change in molecular weight is large when the mixture is allowed to stand under high temperature conditions for a certain period of time, and the heat resistance is poor. Further, the photocurable pressure-sensitive adhesive compositions of Comparative Examples 1 to 3 containing the (meth) acrylic polymers (A'-1) to (A'-3) have extremely high coatability as compared with Example 7. It turns out that it is bad and the adhesiveness is also inferior. Further, it can be seen that the metal members of the photocurable pressure-sensitive adhesive compositions of Comparative Examples 1 and 3 having an acid value outside the upper limit range are easily corroded. Further, the photocurable pressure-sensitive adhesive composition of Comparative Example 4 containing the (meth) acrylic polymer (A'-4) having a weight average molecular weight outside the upper limit range is the same except for the weight average molecular weight. It can be seen that the coatability is extremely inferior to that of the photocurable pressure-sensitive adhesive compositions of Examples 1 and 4 to 6 containing the coalescence (A). Further, the photocurable pressure-sensitive adhesive composition of Comparative Example 5 containing the (meth) acrylic polymer (A'-5) having a weight average molecular weight outside the lower limit range is the same except for the weight average molecular weight (meth) acrylic weight. It can be seen that the adhesiveness is extremely inferior to that of the photocurable pressure-sensitive adhesive compositions of Examples 1 and 4 to 6 containing the coalescence (A). Further, the photocurable pressure-sensitive adhesive composition of Comparative Example 6 containing the (meth) acrylic polymer (A'-6) in which the weight ratio of the cyclization polymerizable monomer (a1) is outside the lower limit range is extremely adhesive. It turns out to be inferior. Further, the photocurable pressure-sensitive adhesive composition of Comparative Example 7 containing the (meth) acrylic polymer (A'-7) in which the weight ratio of the cyclization polymerizable monomer (a1) is out of the upper limit range is tackled. Although it is equivalent to Example 2, it can be seen that the coatability is extremely inferior.

The photocurable pressure-sensitive adhesive composition of the present invention is less corrosive to metal members, has good adhesive properties, and is less likely to cause thickening or gelation due to an increase in molecular weight even under high temperature conditions during coating. Films used for [plate plate protective film, retardation film, light diffusion film, viewing angle enlargement film, reflective film, antireflection film, antiglare film, brightness improving film, etc.] and display substrates (liquid crystal display, organic EL display, etc.) , A substrate for flat panel displays such as plasma displays, field emission displays and electronic papers, and substrates for backlights such as liquid crystal displays, signals and neon signs) are particularly useful as raw materials for adhesives. Further, the photocurable pressure-sensitive adhesive composition of the present invention includes a pressure-sensitive adhesive for various optical disk (VD, CD, DVD, MD, LD, etc.) substrate protective films, and optical lenses such as optical pickup lenses, camera lenses, and lenticular lenses. It can also be used as a raw material for an adhesive for adhering an optically molded product such as a substrate for a touch panel and an optical substrate such as a light guide plate.

Claims (7)

A photocurable pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A), a polyfunctional (meth) acrylic monomer (B), and a photopolymerization initiator (C), wherein the (meth) acrylic polymer (meth) acrylic polymer (meth) A) is a copolymer containing a cyclization polymerizable monomer (a1) and an alkyl (meth) acrylate (a2) as essential constituent monomers, and is a simple polymer constituting the (meth) acrylic polymer (A). The weight ratio of the cyclized polymerizable monomer (a1) in the weight is 1 to 20% by weight, and the weight average molecular weight of the (meth) acrylic polymer (A) is 100,000 to 500,000. A photocurable pressure-sensitive adhesive composition in which the acid value of the acrylic polymer (A) is 4 mgKOH / g or less, and the hydroxyl value of the (meth) acrylic polymer (A) is 3 mgKOH / g or less. The photocurable pressure-sensitive adhesive composition according to claim 1, wherein the cyclizable polymerizable monomer (a1) is a monomer represented by the following general formula (1).

[In the formula (1), R ¹ represents an organic group having 1 to 30 carbon atoms. R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are independently hydrogen atoms or alkyl groups having 1 to 6 carbon atoms, respectively. ] Weight ratio of the cyclized polymerizable monomer (a1) to the alkyl (meth) acrylate (a2) in the monomer constituting the (meth) acrylic polymer (A) {(a1) / (a2)} The photocurable pressure-sensitive adhesive composition according to claim 1 or 2, wherein the amount is 0.01 to 0.3. The invention according to any one of claims 1 to 3, wherein the solubility parameter (SP value) of the (meth) acrylic polymer (A) is 9.2 to 9.9 (cal / cm ³ ) ^1/2 . Photocurable pressure-sensitive adhesive composition. The weight ratio {(A) / (B)} of the (meth) acrylic polymer (A) and the polyfunctional (meth) acrylic monomer (B) in the photocurable pressure-sensitive adhesive composition is 5 to 2000. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 4. The photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 5, which is for a display and / or for an optical member. A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer formed from the photocurable pressure-sensitive adhesive composition according to any one of claims 1 to 6 on at least one surface of a base material.