JP2020100806A - Adhesive composition, and adhesive including the same, adhesive sheet, and laminate - Google Patents

Abstract

To provide an adhesive composition that forms an adhesive that has excellent tackiness and holding power before curing and has excellent shear strength after curing.SOLUTION: An adhesive composition contains an acrylic resin (A), an epoxy compound (B) and a crosslinker (C) of the acrylic resin (A) (excluding the epoxy compound (B)), and the acrylic resin (A) has a glass transition temperature of 20°C or higher, and the epoxy compound (B) has a 25°C viscosity of 3000 mPa s or less.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an adhesive/adhesive composition, and more particularly to an adhesive/adhesive composition that has tackiness under normal conditions and is cured by heating and firmly adhered after being adhered to an adherend. The present invention also relates to a tacky adhesive obtained by cross-linking the above tacky adhesive composition, which has a high level of tackiness and holding power, and has excellent shear strength after curing. Further, the present invention provides an adhesive/adhesive sheet having an adhesive/adhesive layer made of the adhesive/adhesive, or an adhesive/adhesive layer made of the adhesive/adhesive and another member, which are laminated together. The present invention relates to a laminate having excellent holding strength and shear strength for mating surfaces.

Conventionally, liquid adhesives using epoxy compounds have been used for bonding metals and plastics.
Further, as a tacky adhesive having both properties of a pressure-sensitive adhesive and an adhesive, which has adhesiveness (tack) under normal conditions and is hardened by heating after being adhered to an adherend to firmly adhere, A thermosetting pressure-sensitive adhesive composition using an acrylic resin, an epoxy resin, and an epoxy curing agent has also been proposed (see, for example, Patent Document 1).
On the other hand, a tacky adhesive using a solid epoxy resin and an acrylic resin having a relatively low glass transition temperature (Tg) has also been proposed (see, for example, Patent Document 2).

JP, 2016-20502, A International publication WO2013/157567

However, although the adhesive/bonding agent disclosed in Patent Document 1 is excellent in shear strength after curing, the adhesive/bonding agent before curing is inferior in holding power.
Further, the adhesive/bonding agent disclosed in Patent Document 2 does not consider the holding force before curing and the shear strength after curing at all, and does not satisfy both performances.

Under the circumstances, the present invention provides a tacky adhesive composition that forms a tacky adhesive that is excellent in tack and holding power before curing and is also excellent in shear strength after curing. The purpose is.

However, as a result of intensive studies conducted by the present inventors in view of such circumstances, an acrylic resin, an epoxy compound, and a pressure-sensitive adhesive composition containing a cross-linking agent of an acrylic resin have a high glass transition temperature Adhesives that form adhesives with excellent tack and holding power before curing, and also with excellent shear strength after curing by using epoxy resin with low viscosity The present invention was completed by finding out that an agent composition was obtained.

That is, the present invention provides a pressure-sensitive adhesive containing an acrylic resin (A), an epoxy compound (B) and a cross-linking agent (C) for the acrylic resin (A) (excluding the epoxy compound (B)). The adhesive composition, wherein the acrylic resin (A) has a glass transition temperature of 20° C. or higher, and the epoxy compound (B) has a viscosity at 25° C. of 3000 mPa·s or less. The thing is the first gist.

Moreover, this invention makes the adhesive composition which the said adhesive composition which is said 1st summary crosslinks be 2nd summary.

Furthermore, the present invention provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive, which is the second aspect of the invention, as a third aspect, and also from the pressure-sensitive adhesive which is the second aspect. A fourth aspect is a laminated body in which the adhesive/adhesive layer and the other member are laminated.

In the present invention, “curing” means curing of an epoxy compound by heating, and “crosslinking” means crosslinking by a reaction between an acrylic resin and a crosslinking agent.

The present invention is a pressure-sensitive adhesive containing an acrylic resin (A), an epoxy compound (B) and a cross-linking agent (C) for the acrylic resin (A) (excluding the epoxy compound (B)). In the composition, the acrylic resin (A) has a glass transition temperature of 20° C. or higher, and the epoxy compound (B) has a viscosity at 25° C. of 3000 mPa·s or lower. Therefore, the adhesive/adhesive obtained using this adhesive/adhesive composition has an excellent effect that it has excellent tack and holding power in the state before curing and exhibits high shear strength in the state after curing. doing. Therefore, the adhesive composition of the present invention is used for various applications such as building materials, vehicle parts, electronic parts, semiconductor manufacturing processes, member sealing, aviation parts, and sports goods. It can be preferably used for adhesive applications.

The present invention will be described in detail below.
In the present invention, the “monomer having an acryloyl group” means a monomer having a group represented by the general formula “CH ₂ ═CH—C(═O)—” and “(meth)acrylic” means acryl. Alternatively, methacryl means “(meth)acryloyl” means acryloyl or methacryloyl, and “(meth)acrylate” means acrylate or methacrylate.
Further, the “acrylic resin” is a resin obtained by polymerizing a polymerization component containing at least one kind of (meth)acrylate monomer.

In the present invention, the “glass transition temperature” is a value measured by using a differential scanning calorimeter (DSC Q2000, manufactured by TA Instruments). The measurement temperature range is −85° C. to 200° C., and the temperature rising rate is 5° C./minute.

The pressure-sensitive adhesive composition of the present invention contains an acrylic resin (A), an epoxy compound (B), and a crosslinking agent (C) for the acrylic resin (A). Hereinafter, the above (A), (B), and (C) will be described in order.

<Acrylic resin (A)>
The acrylic resin (A) has a glass transition temperature of 20° C. or higher. As such an acrylic resin (A), an acrylic resin obtained by polymerizing a polymerization component containing a (meth)acrylic monomer as a main component and, if necessary, other various polymerizable monomers. Are listed.
In addition, "to be a main component" means that the content of the polymerization component is usually 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more.

Examples of the (meth)acrylic monomer include (meth)acrylic acid or a derivative thereof, and (meth)acrylamide or a derivative thereof.

Examples of the (meth)acrylic acid derivative include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, and 2-methyl-2-nitropropyl (meth). Acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3- Pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl Examples thereof include alkyl esters of (meth)acrylic acid such as 2-propylpentyl (meth)acrylate and n-octadecyl (meth)acrylate.

Other examples of the (meth)acrylic acid derivative include cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate. A biphenyloxy structure-containing (meth)acrylate such as biphenyloxyethyl (meth)acrylate; 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornen-2-yl-methyl (meth) Acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, Such as polycyclic (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, methoxydiethylene glycol ( Containing alkoxy group or phenoxy group such as (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, ethylcarbitol (meth)acrylate, phenoxyethyl (meth)acrylate, alkylphenoxy polyethylene glycol (meth)acrylate (Meth)acrylate; and the like.

Furthermore, examples of the derivative of (meth)acrylic acid include a functional group-containing monomer, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2 -Hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth) ) Hydroxyalkyl (meth)acrylates such as acrylates, hydroxyl groups containing [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanedimethanol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate ( (Meth)acrylate; epoxy group-containing (meth)acrylate such as glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether; 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2- Trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, 3-chloro-2-hydroxypropyl A halogen-containing (meth)acrylate such as (meth)acrylate; an alkylaminoalkyl(meth)acrylate such as dimethylaminoethyl(meth)acrylate; 3-oxetanylmethyl(meth)acrylate, 3-methyl-oxetanylmethyl(meth)acrylate, Examples include oxetane group-containing (meth)acrylates such as 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyl-oxetanylmethyl (meth)acrylate.

Examples of the (meth)acrylamide derivative include N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-alkyl group-containing (meth)acrylamide derivatives such as N-butyl (meth)acrylamide and N-hexyl (meth)acrylamide; N-methylol (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, N-methylol-N -N-hydroxyalkyl group-containing (meth)acrylamide derivatives such as propane (meth)acrylamide; N-aminoalkyl group-containing (meth)acrylamide derivatives such as aminomethyl (meth)acrylamide and aminoethyl (meth)acrylamide; N-methoxy N-alkoxy group-containing (meth)acrylamide derivatives such as methyl (meth)acrylamide and N-ethoxymethyl (meth)acrylamide; N-mercaptoalkyl group-containing (meta) such as mercaptomethyl (meth)acrylamide and mercaptoethyl (meth)acrylamide ) Acrylamide derivatives; heterocyclic ring-containing (meth)acrylamide derivatives such as N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine; and the like.

These (meth)acrylic monomers may be used alone or in combination of two or more. Of these, alkyl esters of (meth)acrylic acid are preferably used, and those having an alkyl group having 1 to 20 carbon atoms are particularly preferable. Further, those having 1 to 12 carbon atoms in the alkyl group are more preferable, those having 1 to 8 are particularly preferable, and those having 1 to 4 are most preferable. This is because a compound having a smaller carbon number tends to have better compatibility with the epoxy compound (B) described later.

Further, among these (meth)acrylic monomers, it is preferable that the monomer having an acryloyl group is contained in an amount of 25% by weight or more, and more preferably 35% by weight or more, based on the total amount of the polymerization components of the acrylic resin (A). Is. By increasing the content ratio of the monomer having an acryloyl group, the transferability after the formation of the tacky adhesive layer becomes excellent and the handleability becomes good without impairing the adhesive property before curing.

As the monomer having an acryloyl group, a monomer containing an acryloyl group such as acrylic acid or a derivative thereof, acrylamide or a derivative thereof is selected from the above-mentioned various (meth)acrylic monomers and used. You can

When an acrylic acid derivative is used as the acryloyl group-containing monomer, for example, the glass transition temperature is high, the shear strength after curing tends to be high, and it is easy to increase the molecular weight of the acrylic resin (A). A monomer having a glass transition temperature of 0° C. or higher when formed into a polymer is preferable, and it is preferable that methyl acrylate is contained from the viewpoint of polymerizability.

When the glass transition temperature is high, the shear strength after curing tends to be high, and the reactivity with the crosslinking agent (C) described below is taken into consideration, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, etc. , Hydroxyalkyl acrylate and the like, which contain a hydroxyl group, are preferred. It is also preferable to use acrylic acid for the same reason as that containing the above hydroxyl group.

When an acrylamide derivative is used as the monomer having an acryloyl group, it contains a dialkyl acrylamide or N-acryloylmorpholine in that it has a high glass transition temperature and excellent compatibility with the epoxy compound (B). Is preferred.

Furthermore, among the above-mentioned acryloyl group-containing monomers, it is preferable to use a large amount of an acryloyl group-containing monomer having a glass transition temperature of 0° C. or higher when formed into a homopolymer so that the resulting acrylic resin (A) maintains a high glass transition temperature. It is possible and suitable.

In the present invention, as the polymerizable monomer (hereinafter referred to as “other polymerizable monomer”) other than the (meth)acrylic monomer that can be used for the acrylic resin (A), for example, crotonic acid, maleic acid, Unsaturated carboxylic acids such as maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamido-N-glycolic acid, cinnamic acid; vinyl acetate, vinyl propionate, vinyl stearate, vinyl benzoate, etc. Acid vinyl ester monomer; Aromatic ring-containing monomer such as styrene and α-methylstyrene; Acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, alkyl vinyl ether, vinyl toluene, vinyl pyridine, vinyl pyrrolidone, itaconic acid dialkyl ester, fumar Examples thereof include acid dialkyl ester, allyl alcohol, acrylic chloride, methyl vinyl ketone, allyl trimethyl ammonium chloride, and dimethyl allyl vinyl ketone. These may be used alone or in combination of two or more.

The acrylic resin (A) used in the present invention preferably contains a functional group-containing monomer, and the functional group-containing monomer is at least one kind selected from a hydroxyl group-containing monomer and a carboxy group-containing monomer. It is preferable to include a monomer. Among them, a functional group-containing monomer having a (meth)acryloyl group is preferable, and a functional group-containing monomer having an acryloyl group is more preferable. Among these, 2-hydroxyethyl acrylate and acrylic acid are particularly preferable.

And, the content of the functional group-containing monomer is preferably 0.1 to 30% by weight, more preferably 1 to 25% by weight, based on the entire polymerization components in the acrylic resin (A). Particularly preferably, it is 3 to 20% by weight. When the amount of the functional group-containing monomer is too small, the cohesive force when forming the adhesive layer tends to decrease, and the tack and the holding force tend to decrease. On the other hand, if the amount is too large, the storage stability of the adhesive layer tends to decrease, and the pot life tends to become short.

The acrylic resin (A) used in the present invention is obtained by appropriately selecting and polymerizing the above-mentioned monomer so that the glass transition temperature is 20° C. or higher.

As the method for polymerizing the acrylic resin (A), conventionally known methods such as solution radical polymerization, suspension polymerization, bulk polymerization, emulsion polymerization and the like can be used. For example, there is a method of mixing or dropping a properly selected polymerization component and a polymerization initiator in an organic solvent, and performing polymerization under predetermined polymerization conditions. Among them, solution radical polymerization and bulk polymerization are preferable and stable. Solution radical polymerization is particularly preferable in that an acrylic resin can be obtained.

Examples of the organic solvent used in the above polymerization reaction include aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, esters such as ethyl acetate and butyl acetate, n-propyl alcohol, isopropyl alcohol. And the like, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. These organic solvents can be used alone or in combination of two or more kinds.

Among these organic solvents, esters such as ethyl acetate and butyl acetate are used in view of easiness of polymerization reaction, chain transfer effect, easiness of drying at the time of coating the adhesive composition, and safety. , Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone are preferable, and ethyl acetate is particularly preferable.

Examples of the polymerization initiator used for such solution radical polymerization include 2,2′-azobisisobutyronitrile and 2,2′-azobis-2-methylbutyronitrile which are ordinary radical polymerization initiators. , 4,4′-azobis(4-cyanovaleric acid), 2,2′-azobis(methylpropionic acid), and other azo initiators, benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, cumene Examples thereof include organic peroxides such as hydroperoxide, which can be appropriately selected and used according to the monomer to be used. These polymerization initiators can be used alone or in combination of two or more.

In this way, the acrylic resin (A) used in the present invention is obtained.

The weight average molecular weight (Mw) of the acrylic resin (A) is preferably 200,000 or more, particularly preferably 200,000 to 1,500,000, further preferably 250,000 to 1,000,000, and particularly preferably 300,000 to 800,000. When the weight average molecular weight is too small, the toughness and cohesive force of the obtained pressure-sensitive adhesive layer tend to decrease, and the tack, holding force and shear strength after curing tend to decrease. Further, if the weight average molecular weight is too large, the viscosity tends to be too high, resulting in increased scaling during polymerization, reduced compatibility with the epoxy compound (B), and reduced handleability. ..

The degree of dispersion [weight average molecular weight (Mw)/number average molecular weight (Mn)] of the acrylic resin (A) is preferably 15 or less, particularly preferably 10 or less, and further preferably 5.5 or less. is there. If the dispersity is too high, the cohesive force tends to decrease. The lower limit of the degree of dispersion is usually 1.

The weight average molecular weight of the acrylic resin (A) is a weight average molecular weight in terms of standard polystyrene molecular weight, and is a high performance liquid chromatograph (manufactured by Japan Waters, "Waters 2695 (main body)" and "Waters 2414 (detector)". )), column: Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , theoretical plate number: 10000 plates/piece, packing material: styrene-divinylbenzene copolymer) , Filler particle diameter: 10 μm) are connected in series and used, and the number average molecular weight can also be measured by the same method. The dispersity can be obtained from the measured values of the weight average molecular weight and the number average molecular weight.

The glass transition temperature (Tg) of the acrylic resin (A) needs to be 20° C. or higher. The temperature is preferably 25 to 200°C, particularly preferably 30 to 180°C. If the glass transition temperature is too low, the shear strength after curing will decrease. If it is too high, the tack before curing tends to be low.

The acrylic resin (A) has a refractive index of usually 1.440 to 1.600. It is preferable that such a refractive index has a small difference in refractive index from the members to be laminated, because the optical loss at the member interface is small.

The above-mentioned refractive index is a value obtained by measuring the thin film acrylic resin (A) using a refractive index measuring device (“Abbe refractometer 1T” manufactured by Atago Co., Ltd.) at NaD line at 23°C.

<Epoxy compound (B)>
Examples of the epoxy compound (B) used in the present invention include aliphatic epoxy compounds, aromatic epoxy compounds, alicyclic epoxy compounds, and the like. The epoxy compound (B) may be a monofunctional epoxy compound having one epoxy group or a polyfunctional epoxy compound having two or more epoxy groups in its structure. These compounds may be used alone or in combination of two or more kinds.

Examples of the aliphatic epoxy compounds include monofunctional aliphatic epoxy compounds such as alkyl glycidyl ether, alkoxy glycidyl ether, and allyl glycidyl ether; neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and ethylene. Bifunctional aliphatic epoxy compounds such as glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether; glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, isocyanuric acid triglycidyl and its derivatives , Pentaerythritol triglycidyl ether and other trifunctional aliphatic epoxy compounds; pentaerythritol tetraglycidyl ether, diglycerol tetraglycidyl ether, ditrimethylolpropane tetraglycidyl ether and other tetrafunctional aliphatic epoxy compounds; polyglycerol pentaglycidyl ether, 5-functional aliphatic epoxy compounds such as pentaerythritol pentaglycidyl ether and dipentaerythritol pentaglycidyl ether; 6-functional aliphatic epoxy compounds such as sorbitol hexaglycidyl ether and dipentaerythritol hexaglycidyl ether; trimethylolpropane poly Other polyfunctional aliphatic epoxy compounds such as glycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like can be mentioned.

Examples of the aromatic epoxy compounds include monofunctional aromatic epoxy compounds such as phenol glycidyl ether and EO (ethylene oxide) modified phenol glycidyl ether; diglycidyl terephthalate, diglycidyl-o-phthalate, diglycidyl resorcinol ether. , Bifunctional aromatic epoxy compounds such as bisphenol A type diglycidyl compound, bisphenol F type diglycidyl compound, biphenyl type diglycidyl compound; other polyfunctional aromatic epoxy compounds such as phenol novolac type epoxy compound and cresol novolac type epoxy compound A compound etc. are mentioned.

Examples of the alicyclic epoxy compounds include bifunctional alicyclic epoxy compounds such as hydrogenated products of bisphenol A type diglycidyl compounds, hydrogenated products of bisphenol F type diglycidyl compounds, and hydrogenated products of biphenyl type diglycidyl compounds. Etc.

Among the above epoxy compounds (B), epoxy compounds having at least three epoxy groups are preferable because the shear strength after curing tends to increase. In addition, aliphatic epoxy compounds are preferable from the viewpoint of excellent tack. Particularly, trimethylpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, and diglycerol polyglycidyl ether are preferable.

The viscosity of the epoxy compound (B) at 25° C. needs to be 3000 mPa·s or less. It is preferably 2000 mPa·s or less, more preferably 1500 mPa·s or less, and particularly preferably 1000 mPa·s or less. The lower limit of the viscosity is usually 5 mPa·s, preferably 10 mPa·s. If the viscosity is too high, the tackiness of the tacky adhesive layer will decrease. If the viscosity is too low, the cohesive force of the adhesive layer tends to decrease. When two or more kinds of epoxy compounds (B) are used, the viscosity when the epoxy compounds (B) to be used are uniformly mixed should be within the above range.
The pressure-sensitive adhesive composition of the present invention contains the epoxy compound (B) having the above-mentioned viscosity, that is, the liquid epoxy compound (B) at 25° C. It has an excellent balance of adhesive strength, holding power and tack.

The viscosity of the epoxy compound (B) is a value measured using a B-type viscometer according to JIS K7233.

Moreover, 100-2000 are preferable, as for the weight average molecular weight of the said epoxy-type compound (B) (By the above-mentioned measuring method, the same below), 200-1800 are more preferable, and 250-1500 are especially preferable. If the molecular weight is too low, volatilization at high temperature or white smoke tends to occur, and if it is too high, the compatibility with the acrylic resin (A) tends to decrease.

Further, the content of the epoxy compound (B) is preferably 25 to 300 parts by weight, more preferably 30 to 250 parts by weight, based on 100 parts by weight of the acrylic resin (A). It is particularly preferably 40 to 200 parts by weight, and further preferably 50 to 150 parts by weight. If the content of the epoxy compound (B) with respect to the acrylic resin (A) is too low, the tackiness of the tacky adhesive decreases and the handling property decreases, or the adhesiveness when the members are attached and cured. If the amount is too large, the holding power of the pressure-sensitive adhesive tends to decrease.

<Crosslinking agent (C) for acrylic resin (A)>
Examples of the cross-linking agent (C) (hereinafter simply referred to as “cross-linking agent (C)”) used as a cross-linking agent for the acrylic resin (A) include, for example, isocyanate cross-linking agents, aziridine cross-linking agents, and melamine cross-linking agents. , Aldehyde-based crosslinking agents, and metal chelate-based crosslinking agents. The compounds used as the epoxy compound (B) are excluded.

Examples of the above-mentioned isocyanate cross-linking agent include tolylene diisocyanate compounds such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate; 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetra Xylylene diisocyanate compounds such as methyl xylylene diisocyanate; aromatic isocyanate compounds such as 1,5-naphthalene diisocyanate and triphenylmethane triisocyanate; hexamethylene diisocyanate, isophorone diisocyanate, and these isocyanate compounds and trimethylolpropane Examples thereof include adducts with the polyol compound, burettes and isocyanurates of these polyisocyanate compounds.

Examples of the aziridine-based crosslinking agent include tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-β-aziridinylpropionate, and N,N′-diphenylmethane-4. , 4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide) and the like.

Furthermore, examples of the melamine-based cross-linking agent include hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentyloxymethylmelamine, hexahexyloxymethylmelamine, and melamine resin. To be

Examples of the aldehyde cross-linking agent include glyoxal, malondialdehyde, succindialdehyde, maleindialdehyde, glutardialdehyde, formaldehyde, acetaldehyde and benzaldehyde.

And as the metal chelate-based cross-linking agent, for example, acetylacetone or acetoacetyl ester coordination compound of polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium. Etc.

The cross-linking agent (C) may be used alone or in combination of two or more kinds. Among the above-mentioned cross-linking agents (C), the isocyanate-based cross-linking agents are preferably used, in particular, from the viewpoint of improving the adhesiveness to the base material and the reactivity with the acrylic resin (A), among them. The tolylene diisocyanate-based compound and the hexamethylene diisocyanate-based cross-linking agent are preferable because they have excellent holding power and adhesive properties when used as a tacky adhesive.

The content of the crosslinking agent (C) is preferably 0.1 to 30 parts by weight, more preferably 1 to 25 parts by weight, and particularly preferably 2. to 100 parts by weight of the acrylic resin (A). 5 to 20 parts by weight. When the content ratio of the cross-linking agent (C) to the acrylic resin (A) is within the above range, the cohesive adhesive tends to have particularly excellent holding power and tack.

The acrylic pressure-sensitive adhesive composition of the present invention contains the above-mentioned essential components acrylic resin (A), epoxy compound (B) and cross-linking agent (C). It is preferable to contain a curing agent (D) that reacts with the epoxy compound (B) (hereinafter, simply referred to as "curing agent (D)") because it can be efficiently cured when used as an adhesive.

<Curing agent (D)>
Examples of the curing agent (D) include amines, polyamides, imidazoles, polymercaptan curing agents, and acid anhydrides. These may be used alone or in combination of two or more. Among the above curing agents (D), dicyandiamide, which is an amine compound, and organic acid hydrazide are preferable, in particular, in terms of excellent storage stability when used as an adhesive and shear strength during curing, and organic acid hydrazide is preferable. Among these, adipic acid hydrazide is particularly preferable because it is excellent in curing speed and shear strength after curing.

The curing agent (D) may be liquid or solid, but is solid in terms of storage stability when used as a tacky adhesive and pot life of the tacky adhesive composition. Further, it is preferable that the coating film is dispersed and contained in a powder state in that the coating film becomes smooth and the adhesive area with the member increases when curing and the shear strength after curing increases. preferable. When a powder is used as the curing agent (D), the particle size of the powder should be set to be 1.2 times or less the film thickness when the adhesive layer is formed. Is preferable, and it is more preferable that the amount is 1 time or less.

When the curing agent (D) is used, its content is preferably 10 to 100 parts by weight, and particularly 15 to 80 parts by weight, relative to 100 parts by weight of the epoxy compound (B). More preferably, it is 25 to 50 parts by weight, and most preferably. If the content ratio of the curing agent (D) to the epoxy compound (B) is less than the above range, the curing rate tends to be slow or the curing temperature tends to be high. There is a tendency that streaks are generated during the work and the pot life of the adhesive composition is shortened.

The adhesive composition of the present invention may contain various optional components other than the above curing agent (D) as long as the effects of the present invention are not impaired. Hereinafter, those optional components will be described.

<Other optional ingredients>
Other optional components include, for example, conductive agents such as carbon and metal; inorganic fillers such as metal particles and glass particles; urethane resin, rosin, rosin ester, hydrogenated rosin ester, phenol resin, aliphatic petroleum resin, and oil. Tackifiers such as aromatic petroleum resins and styrene resins; fillers; antioxidants; UV absorbers; silane coupling agents; crosslinking accelerators such as ionic compounds, peroxides, urethanization catalysts; acetylacetone, etc. And various additives such as a crosslinking retarder. These may be used alone or in combination of two or more.

In addition to the above-mentioned additives, a small amount of impurities contained in the raw materials for manufacturing the constituents of the acrylic pressure-sensitive adhesive composition may be contained.

The pressure-sensitive adhesive composition of the present invention comprises the acrylic resin (A), the epoxy compound (B) and the crosslinking agent (C), preferably a curing agent (D), and optionally other optional components. It can be obtained by mixing.

The method of mixing these components is not particularly limited, and various methods such as a method of mixing the respective components at once or a method of mixing the optional components and then the remaining components at once or sequentially are mixed. Can be adopted.

The pressure-sensitive adhesive composition of the present invention can be made into a pressure-sensitive adhesive by the acrylic resin (A) and the cross-linking agent (C) reacting and cross-linking. A pressure-sensitive adhesive sheet can be obtained by laminating and forming an adhesive layer on a substrate such as a plastic film.

In addition, the adhesive/adhesive sheet is preferably a substrateless double-sided sheet in which separators (release sheets) are laminated on both sides of the adhesive/adhesive layer, in terms of easy handling.

As the method for producing the pressure-sensitive adhesive sheet, for example, after the pressure-sensitive adhesive composition is applied to a separator or a base material and dried, a separator (if applied to the separator, a separator having a different peeling force) is attached. In this case, a method of performing treatment by at least one of room temperature (non-heated state) and aging in the heated state can be mentioned.

The above-mentioned aging treatment is carried out in order to balance the sticky physical properties of the pressure-sensitive adhesive as the reaction time of the chemical crosslinking of the acrylic resin (A) and the cross-linking agent (C). Is usually room temperature (20±10° C.) to 40° C., and the time is usually 1 to 30 days. Specifically, for example, 23° C. for 1 to 20 days, 40° C. for 1 to 7 days, etc. Good.

At the time of coating the above-mentioned pressure-sensitive adhesive composition, it is preferable to dilute the pressure-sensitive adhesive composition with a solvent before coating, and the solid content concentration is preferably 5 to 65% by weight, particularly preferably 20. Is 55% by weight. The solvent is not particularly limited as long as it can dissolve the adhesive composition. For example, ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate and ethyl acetoacetate, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, aromatic solvents such as toluene and xylene, methanol, ethanol and propyl alcohol. Alcohol solvents such as Among these, ethyl acetate is preferably used in terms of solubility, drying property, price and the like.

The viscosity of the diluted adhesive composition is preferably 500 to 15000 mPa·s/25°C, more preferably 1000 to 10000 mPa·s/25°C. If the viscosity is too low, when a component having a high specific gravity is used, the component tends to settle.

Examples of the method for applying the adhesive composition include roll coating, die coating, gravure coating, comma coating, and screen printing.

And the thickness of the adhesive layer in the obtained adhesive sheet is preferably 5 to 250 μm, particularly preferably 25 to 200 μm, and further preferably 50 to 175 μm. If the pressure-sensitive adhesive layer is too thin, the thickness accuracy tends to be low or the pressure-sensitive adhesive force tends to be low, and if it is too thick, the pressure-sensitive adhesive layer protrudes from the end when the pressure-sensitive adhesive sheet is rolled. There is a tendency to

The gel fraction of the adhesive layer produced by the above method is preferably 10 to 90% by weight, particularly preferably 15 to 70% by weight, from the viewpoint of adhesion with a member, reworkability, and holding power. %, and more preferably 20 to 60% by weight. If the gel fraction of the tacky-adhesive layer is too low, the cohesive force will be low, and the members will tend to shift when the tacky-adhesive is cured. Sufficient adhesion between the adhesive layer and the member interface cannot be obtained, and the shear strength after curing tends to decrease.

The gel fraction is a measure of the degree of crosslinking (degree of curing) and is calculated, for example, by the following method. That is, the adhesive/adhesive is collected from an adhesive/adhesive sheet having an adhesive/adhesive layer formed on the surface of a base material, etc. by picking, and the adhesive/adhesive is wrapped in a 200-mesh SUS wire mesh and kept at 23°C. By immersing in the adjusted ethyl acetate for 24 hours, the weight percentage of the insoluble adhesive component remaining in the wire net to the weight of the adhesive layer before immersion in ethyl acetate is taken as the gel fraction.

In the present invention, the adhesive layer is cured by heating and the adhesive strength is increased. As the heating conditions, the heating temperature is preferably 100 to 250°C, more preferably 120 to 200°C, and particularly preferably 130 to 185°C. If the temperature is too low, the curing time becomes long and the workability tends to decrease, and if it is too high, the epoxy compound tends to volatilize or ignite. The heating time is preferably 5 to 180 minutes, more preferably 30 to 120 minutes, and particularly preferably 45 to 90 minutes. If this time is too short, the shear strength tends to decrease, and if it is too long, the workability tends to decrease.

And, the ratio of the shear strength after curing (MPa) to the shear strength before curing (MPa) is preferably 10 or more in order to balance the adhesive property before curing with the shear strength and durability after curing. It is preferably 20 or more, particularly preferably 100 or more. The upper limit of the ratio of the shear strength after curing to the shear strength before curing is usually 100,000.

The pressure-sensitive adhesive layer of the present invention has excellent characteristics that it has excellent transferability and holding power before being cured and that it exhibits high shear strength after being cured. Therefore, it can be suitably used for various applications such as building materials, in-vehicle parts, electronic parts, semiconductor manufacturing processes, member encapsulation, aviation parts, sporting goods, and other adhesive bonding applications.

The adhesive/adhesive sheet having this adhesive/adhesive layer can be simply peeled off by separating the separator covering the surface of the adhesive/adhesive layer and adhering the adhesive/adhesive layer surface to the target member surface. Since the adhesive layer can be transferred to, it is very convenient to work.

Then, a laminate obtained by laminating other members via the adhesive/adhesive layer has a high holding force before the adhesive/adhesive layer is cured, and exhibits high shear strength after curing. It is of excellent quality without being easily displaced or peeled off.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples, “part” and “%” mean weight basis.
The following ingredients were prepared prior to the examples.

<Acrylic resin (A)>
[Preparation of acrylic resin (A-1)]
A 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer was charged with 72 parts of ethyl acetate, 24 parts of methyl ethyl ketone, and 0 of azobisisobutyronitrile (AIBN) as a polymerization initiator. After charging 0.036 parts and heating to reach the boiling point of the internal temperature, 74.5 parts of methyl acrylate, 20 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl acrylate, 0.5 part of acrylic acid, 4 parts of ethyl acetate, polymerization A mixed solution of 0.036 parts of the initiator was added dropwise over 2 hours while maintaining the boiling state. While continuing the reaction thereafter, a polymerization initiator (AIBN) was added twice, and the mixture was reacted for 7 hours and then diluted to obtain an acrylic resin (A-1) solution (solid content 38.0%, viscosity 13500 mPa·s). /25°C, acrylic resin (A-1): weight average molecular weight (Mw) 402,000, dispersity (Mw/Mn) 3.3, glass transition temperature (Tg) 21.5°C) were obtained.

[Preparation of acrylic resin (A-2)]
In the preparation of the acrylic resin (A-1), acrylic was used except that the polymerizable monomer composition was 49.5 parts of methyl acrylate, 45 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl acrylate, and 0.5 parts of acrylic acid. Acrylic resin (A-2) solution (solid content 36.0%, viscosity 6040 mPa·s/25° C., acrylic resin (A-2): weight average) The molecular weight (Mw) was 25,000, the dispersity (Mw/Mn) was 2.1, and the glass transition temperature (Tg) was 39.8°C.

<Epoxy compound (B)>
The following were prepared as an epoxy compound (B).
Epoxy compound (B-1) [Denacol EX-321 (trimethylolpropane polyglycidyl ether), viscosity 130 mPa·s/25° C., epoxy equivalent 140 g/mol, number of epoxy groups 2-3, Nagase Chemtex Co.]
Epoxy compound (B-2) [Denacol EX-411 (pentaerythritol polyglycidyl ether), viscosity 800 mPa·s/25° C., epoxy equivalent 229 g/mol, number of epoxy groups 3-4, manufactured by Nagase Chemtex Co.]
Epoxy compound (B-3) [Denacol EX-421 (diglycerol polyglycidyl ether), viscosity 650 mPa·s/25° C., epoxy equivalent 159 g/mol, 3 epoxy groups, manufactured by Nagase Chemtex Co.]
Epoxy compound (B′-1) [Denacol EX-521 (polyglycerol polyglycidyl ether), viscosity 4400 mPa·s/25° C., epoxy equivalent 183 g/mol, 4 or more epoxy groups, manufactured by Nagase Chemtex Co.]
-Epoxy compound (B'-2) [Denacol EX-612 (sorbitol polyglycidyl ether), viscosity 11900 mPas/25°C, epoxy equivalent 166 g/mol, number of epoxy groups 4 or more, Nagase Chemtex Co., Ltd.]
-Epoxy compound (B'-3) [Denacol EX-614B (sorbitol polyglycidyl ether), viscosity 5000 mPas/25°C, epoxy equivalent 173 g/mol, number of epoxy groups 4 or more, Nagase Chemtex Co., Ltd.]
Epoxy compound (B'-4) [Adekaresin EP-4000, viscosity 4500 mPa.s/25[deg.] C., epoxy equivalent 320 g/mol, two epoxy groups, manufactured by ADEKA]
Epoxy compound (B'-5) [Adekaresin EP-4300E (bisphenol A type epoxy resin), viscosity 8000 mPas/25°C, epoxy equivalent 185 g/mol, two epoxy groups, manufactured by ADEKA]
-Epoxy compound (B'-6) [Adekaresin EP-4901 (bisphenol F type epoxy resin), viscosity 3500 mPa-s/25°C, epoxy equivalent 170 g/mol, epoxy group number 2, ADEKA company]

<Crosslinking agent (C)>
The following were used as the crosslinking agent (C).
(C-1): Adduct of tolylene diisocyanate and trimethylol propane (Tosoh Corp., Coronate L55E)

<Curing agent (D)>
The following were used as the curing agent (D).
(D-1): adipic acid dihydrazide (manufactured by Mitsubishi Chemical Corporation, ADH)

<Examples 1 to 4, Comparative Examples 1 to 6>
The above components were blended according to Table 1 below, and the solid content concentration was adjusted to a range of 30 to 60% using ethyl acetate to obtain an adhesive composition.

Using the obtained pressure-sensitive adhesive composition, a sample pressure-sensitive adhesive sheet was prepared according to the procedure described below, and its ball tack, holding power, and shear strength after curing were evaluated. The evaluation method and evaluation criteria for each item are as described below.
The results are also shown in Table 1 below.

<Sample: Preparation of tacky adhesive sheet>
The adhesive composition was applied to a heavy release silicone separator having a thickness of 38 μm (SPPET03 38BU manufactured by Mitsui East Cello Co., Ltd.) using a comma coater so that the thickness after drying was 50 μm, and dried at 100° C. for 3 minutes. .. Then, a 38 μm thick light-release silicone separator (SPPET01 38BU manufactured by Mitsui East Cello Co., Ltd.) was attached to the surface of the dried pressure-sensitive adhesive layer to produce a pressure-sensitive adhesive sheet (light-release silicone separator/adhesive adhesive). Layer/heavy release silicone separator).

<Ball tack>
After peeling off the light release silicone separator of the pressure-sensitive adhesive sheet and transferring it to a PET film, the heavy release silicone separator is peeled off, in accordance with JIS Z 0237, 23° C. at a tilt plate angle of 30°, and relative humidity of 50%. The ball tack test of the adhesive layer in the atmosphere was performed. The evaluation criteria are as follows.
◎・・・ball number over 5 ○・・・ball number 3 or more and 5 or less ×・・・ball number under 3

<Holding power>
After peeling the light release silicone separator of the adhesive sheet and transferring to a PET film, the heavy release silicone separator is removed, and the adhesive layer side is polished so that the attachment area is 25 mm x 25 mm. After sticking to a plate and leaving it at 23°C x 50% RH for 30 minutes, a load of 1 kg was applied under the condition of 40°C, and it was displaced according to the measuring method of the holding force of JIS Z 0237. Was evaluated. The evaluation criteria are as follows.
○・・・No deviation in 24 hours △・・・Displacement in 24 hours ×・・・Drop in 24 hours

<Shear strength after curing>
The adhesive sheet was cut into a size of 25 mm×12.5 mm and transferred to a SUS plate. An SUS plate of the same size is attached to the opposite side of the transferred SUS plate, the attached portion is fixed with a clip, and cured at 140°C for 1 hour, and then under the condition of 23°C x 50% RH, AUTO Graph AG-X Plus. (Shimadzu) was used to measure the shear strength (MPa) at a speed of 5 mm/min. The evaluation criteria are as follows.
◯: 10 MPa or more △: 5 MPa or more and less than 10 MPa ×... less than 5 MPa

Further, the adhesive strength of the adhesive sheet prepared using the adhesive composition of Example 1 above was measured according to the following evaluation method, and the shear strength ratio before and after curing was determined.

<Shear strength ratio before and after curing>
The adhesive/adhesive sheet produced using the adhesive/adhesive composition of Example 1 was cut into a size of 25 mm×12.5 mm and transferred to a SUS plate. A SUS plate of the same size was attached to the opposite side of the transferred SUS plate, and the attached portion was fixed with a clip and left standing for 1 hour under the condition of 23°C x 50% RH. Then, the shear strength (MPa) before curing was measured at a speed of 5 mm/min using an AUTO Graph AG-X Plus (manufactured by Shimadzu) under the condition of 23°C x 50% RH.
Next, the shear strength ratio before and after curing was calculated by the following formula using the shear strength before curing and the shear strength after curing obtained by the above measurement, and it was 176.
Shear strength ratio before and after curing = Shear strength after curing (MPa)/Shear strength before curing (MPa)

From the above results, the pressure-sensitive adhesives using the pressure-sensitive adhesive compositions of Examples 1 to 4 were excellent in tack and holding power before curing, and further had high shear strength after curing.
On the other hand, the tacky-adhesives using the tacky-adhesive compositions of Comparative Examples 1 to 6, which do not contain the epoxy compound (B) having a specific viscosity, are inferior in tack before curing, and are It was inferior to that of No. 4 in physical property balance.

The pressure-sensitive adhesive composition of the present invention has excellent tack and holding power in the state before curing, and exhibits high shear strength in the state after curing, therefore, various applications, for example, for building materials, automotive parts, It is suitable for adhesive and adhesive applications for electronic parts, semiconductor manufacturing processes, member encapsulation, aviation parts, and sports equipment.

Claims (11)

A pressure-sensitive adhesive composition containing an acrylic resin (A), an epoxy compound (B), and a cross-linking agent (C) of the acrylic resin (A) (excluding the epoxy compound (B)). And the glass transition temperature of the acrylic resin (A) is 20° C. or higher, and the viscosity of the epoxy compound (B) at 25° C. is 3000 mPa·s or less. .. The pressure-sensitive adhesive composition according to claim 1, wherein the acrylic resin (A) has a weight average molecular weight of 200,000 or more. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the epoxy compound (B) contains an epoxy compound having at least three epoxy groups. The adhesive composition according to any one of claims 1 to 3, wherein the epoxy compound (B) is an aliphatic epoxy compound. Content of the said epoxy compound (B) is 25-300 weight part with respect to 100 weight part of acrylic resin (A), The viscosity as described in any one of Claims 1-4. Adhesive composition. The adhesive composition according to any one of claims 1 to 5, further comprising a curing agent (D) that reacts with the epoxy compound (B). A pressure-sensitive adhesive, comprising the pressure-sensitive adhesive composition according to any one of claims 1 to 6 crosslinked. The adhesive according to claim 7, which is cured by heating at 100 to 250°C. The ratio of the shear strength (MPa) after curing with respect to the shear strength (MPa) before curing is 10 or more, The adhesive agent of Claim 8 characterized by the above-mentioned. An adhesive/adhesive sheet comprising an adhesive/adhesive layer made of the adhesive/adhesive according to any one of claims 8 to 9. A layered product, in which a tacky-adhesive layer made of the tacky-adhesive according to any one of claims 8 to 9 and another member are stacked.