JPWO2020027180A1 - Adhesive composition and adhesive tape - Google Patents

Abstract

It is an object of the present invention to provide an adhesive composition having high adhesive strength and exhibiting high adhesiveness even when the adhesive layer of the adhesive tape used is thin. The pressure-sensitive adhesive composition of a certain aspect is a pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A) having a weight average molecular weight of 700,000 or more and a synthetic hydrocarbon-based pressure-sensitive adhesive resin (B). The (meth) acrylic polymer (A) is a polymer obtained by polymerizing a monomer containing a (meth) acrylic monomer containing 60% by mass or more of n-butyl (meth) acrylate (a1), and is a (meth) acrylic polymer. The content of the synthetic hydrocarbon-based tackifier resin (B) is 40% by mass or more and 60% by mass or less with respect to the total mass of (A) and the synthetic hydrocarbon-based tackifier resin (B).

Description

The present invention relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition.

Conventionally, adhesive tapes have been widely used for fixing parts of OA equipment and electronic equipment. In recent years, OA equipment and electronic equipment have been made lighter, thinner, shorter and smaller, and the adhesive tape used for fixing these parts is also required to be thinner.

However, the adhesive strength of the adhesive tape generally decreases as the thickness of the pressure-sensitive adhesive layer decreases. Especially in the region where the thickness of the pressure-sensitive adhesive layer is 10 μm or less, the adhesive strength is remarkably reduced. Therefore, it is difficult to develop a sufficiently strong adhesive force even under thin film conditions, and development of an adhesive tape having a high adhesive force even if it is thin is strongly desired.

Patent Document 1 discloses a pressure-sensitive adhesive composition for a thin film in which 40% by mass to 60% by mass of a pressure-imparting resin is added to the pressure-sensitive adhesive, and forms a pressure-sensitive adhesive layer of 2 to 10 μm.
However, the tackifier resin used in the examples of Patent Document 1 is a rosin-based resin. Generally, rosin-based resins are yellow to orange, and the color of the sheet may be a problem. In addition, since the compatibility with the acrylic pressure-sensitive adhesive is poor, the adhesive strength cannot be significantly improved, and haze may become a problem.
Moreover, many rosin-based resins have carboxyl groups or hydroxyl groups in their structures, which may inhibit cross-linking between adhesives. Therefore, if a large amount of rosin-based resin is used, the holding force and the constant load peeling property may be deteriorated.

Patent Document 2 discloses a pressure-sensitive adhesive composition containing a (meth) acrylic polymer derived from n-butyl acrylate, a pressure-imparting resin, and a cross-linking agent, but the weight of the polymer used in the examples. Since the average molecular weight is 500,000, the adhesive strength is not high, and since the tackifier resin used is a rosin-based resin, it is presumed that the color is not preferable.

JP-A-2007-169327 Japanese Unexamined Patent Publication No. 2012-162703

In view of the above problems, it is an object of the present invention to provide a pressure-sensitive adhesive composition having high adhesive strength and exhibiting high adhesiveness even when the pressure-sensitive adhesive layer of the adhesive tape used is thin.

That is, the present invention includes the following.
[1] A pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A) having a weight average molecular weight of 700,000 or more and a synthetic hydrocarbon-based pressure-sensitive adhesive resin (B).
The (meth) acrylic polymer (A) is a polymer obtained by polymerizing a monomer containing 60% by mass or more of n-butyl (meth) acrylate (a1).
The content of the synthetic hydrocarbon-based tackifier resin (B) is 40% by mass or more and 60% by mass or less with respect to the total mass of the (meth) acrylic polymer (A) and the synthetic hydrocarbon-based tackifier resin (B). A pressure-sensitive adhesive composition.
[2] The pressure-sensitive adhesive composition according to [1], wherein the synthetic hydrocarbon-based pressure-sensitive adhesive resin (B) is a styrene-based resin.
[3] The pressure-sensitive adhesive composition according to [1] or [2], which comprises a cross-linking agent.
[4] The (meth) acrylic polymer (A) is a polymer obtained by polymerizing a monomer containing a (meth) acrylic monomer containing 80% by mass or more of n-butyl (meth) acrylate, [1] to [1] to [ 3] The pressure-sensitive adhesive composition according to any one of the above items.
[5] The item according to any one of [1] to [4], which contains 0.01 to 3.0 parts by mass of a silane coupling agent with respect to 100 parts by mass of the resin solid content of the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition according to the above.
[6] An adhesive tape comprising an adhesive layer comprising the adhesive composition according to any one of [1] to [5].
[7] The adhesive tape according to [6], wherein adhesive layers are provided on both sides of the base material.
[8] The adhesive tape according to [6] or [7], wherein the total thickness excluding the release film is 25 μm or less.
[9] The adhesive tape according to any one of [6] to [8], wherein the adhesive layer occupies 40% or more of the total thickness excluding the release film.
[10] The adhesive tape according to any one of [6] to [9], which is used for fixing members of electronic devices.

The pressure-sensitive adhesive composition of the present invention can provide a highly adhesive pressure-sensitive adhesive tape. Furthermore, even a thin adhesive tape exhibits high adhesiveness, so that it can be used for small OA equipment and electronic equipment.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the description of the embodiment of the invention.

[Adhesive composition]
The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A) having a weight average molecular weight of 700,000 or more and a synthetic hydrocarbon-based pressure-sensitive adhesive resin (B). The (meth) acrylic polymer (A) is a polymer obtained by polymerizing a monomer containing 60% by mass or more of n-butyl (meth) acrylate (a1), and is a polymer obtained by polymerizing the (meth) acrylic polymer (A) and a synthetic hydrocarbon. The content of the synthetic hydrocarbon-based tackifier resin (B) is 40% by mass or more and 60% by mass or less with respect to the total mass of the system-based tackifier resin (B).
Hereinafter, the configuration will be specifically described.

<(Meta) Acrylic Polymer (A)>
The pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic polymer (A). The (meth) acrylic polymer (A) is obtained by polymerizing at least n-butyl (meth) acrylate (a1) and, if necessary, a monomer having copolymerizability with the n-butyl (meth) acrylate (a1). Here, the (meth) acrylate monomer is a monomer having a (meth) acryloyl group.
Examples of the monomer component forming the (meth) acrylic polymer (A) include the monomer (a2) described later and the monomer (a3) in addition to the n-butyl (meth) acrylate (a1).

In the present specification, "(meth) acrylic" means to include both "acrylic" and "methacrylic", and "(meth) acrylate" includes both "acrylate" and "methacrylate". "(Meta) acryloyl" means to include both "acryloyl" and "methacrylic acid".

<N-Butyl (meth) acrylate (a1)>
Among the monomer components forming the (meth) acrylic polymer (A), n-butyl (meth) acrylate (a1) is 60% by mass or more, preferably 70% by mass, from the viewpoint of heat resistance and adhesiveness of the pressure-sensitive adhesive composition. % Or more, more preferably 80% by mass or more.

<Monomer (a2)>
The monomer (a2) may be further contained as the monomer forming the (meth) acrylic polymer (A).
Examples of the monomer (a2) include alkyl (meth) acrylates other than n-butyl (meth) acrylate, alicyclic-containing (meth) acrylate, aryl (meth) acrylate, aralkyl (meth) acrylate, alkoxyalkyl (meth) acrylate, and alkoxy. Examples thereof include polyalkylene glycol mono (meth) acrylate and aryloxyalkyl (meth) acrylate.

Examples of the alkyl (meth) acrylate other than the n-butyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and isobutyl (meth) acrylate. , Tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (Meta) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate , Isostearyl (meth) acrylate can be mentioned.

Examples of the alicyclic-containing (meth) acrylate include cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and 4-tert-butylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and adamantyl (meth) acrylate. Be done.

Examples of the aryl (meth) acrylate include phenyl (meth) acrylate, and examples of the aralkyl (meth) acrylate include benzyl (meth) acrylate.

Examples of the alkoxyalkyl (meth) acrylate include methoxymethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, and 3-ethoxypropyl (meth) acrylate. Examples thereof include meta) acrylate, 4-methoxybutyl (meth) acrylate, and 4-ethoxybutyl (meth) acrylate.

Examples of the alkoxypolyalkylene glycol mono (meth) acrylate include methoxydiethylene glycol mono (meth) acrylate, methoxydipropylene glycol mono (meth) acrylate, ethoxytriethylene glycol mono (meth) acrylate, and ethoxydiethylene glycol mono (meth) acrylate. Examples thereof include methoxytriethylene glycol mono (meth) acrylate.

Examples of the aryloxyalkyl (meth) acrylate include phenoxymethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2-triloxyethyl (meth) acrylate, xsilyloxymethyl (meth) acrylate, and naphthyloxymethyl. Examples include (meth) acrylate.

The monomer (a2) may be used alone or in combination of two or more.

The total amount of the n-butyl (meth) acrylate (a1) and the monomer (a2) in the monomer component forming the (meth) acrylic polymer (A) is preferably 70% by mass or more, more preferably 80% by mass. The above is more preferably 85% by mass.

<Monomer (a3)>
The monomer forming the (meth) acrylic polymer (A) preferably contains the monomer (a3). The monomer (a3) is a crosslinkable group-containing monomer. Examples of the crosslinkable group-containing monomer include a carboxyl group-containing monomer and a hydroxyl group-containing monomer.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, β-carboxyethyl (meth) acrylate, 5-carboxypentyl (meth) acrylate, crotonic acid, maleic acid, and fumaric acid.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and 2-. Hydroxy-3-phenoxypropyl (meth) acrylates can be mentioned.

The monomer (a3) may be used alone or in combination of two or more.

Among the monomer components used to form the (meth) acrylic polymer (A), the amount of the monomer (a3) used is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, and further. It is preferably 1 to 8% by mass. In such an embodiment, an appropriate crosslinked structure can be formed by the reaction of the (meth) acrylic polymer (A) with the crosslinking agent described later.

<Other monomers (a4)>
The copolymerizable monomer may further contain other monomers (a4) other than (a1) to (a3).

Examples of the other monomer (a4) include an amino group-containing monomer, an amide group-containing monomer, a glycidyl group-containing monomer, a vinyl group-containing monomer, and a polymerizable macromonomer.

Examples of the amino group-containing monomer include dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; examples of the amide group-containing monomer include (meth) acrylamide, N-methyl (meth) acrylamide, and N. -Ethyl (meth) acrylamide can be mentioned; examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether; examples of the vinyl group-containing monomer include vinyl acetate. , Ethylene, propylene, isobutylene, vinyl chloride, styrene, α-methylstyrene, butadiene, isoprene, chloroprene and the like.

Examples of the polymerizable macromonomer include a macromonomer in which the main chain constituent monomer is methyl methacrylate (product name: 45% AA-6 (AA-6S), AA-6; manufactured by Toa Synthetic Co., Ltd.), and a main chain constituent monomer. Is a butyl acrylate macromonomer (product name: AB-6; manufactured by Toa Synthetic Co., Ltd.) A macromonomer whose main chain is a styrene / acrylonitrile copolymer (product name: AN-6S; manufactured by Toa Synthetic Co., Ltd.) Can be mentioned.

In addition, the monomer (a4) may be used alone or in combination of two or more.

Of the 100% by mass of the monomer component used to form the (meth) acrylic polymer (A), the amount of the other monomer (a4) used is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably. It is 10% by mass or less.

The weight average molecular weight (Mw) of the (meth) acrylic polymer (A) measured by the gel permeation chromatography (GPC) method is 700,000 or more, preferably 800,000 or more, and more, from the viewpoint of adhesiveness. It is preferably 900,000 or more.

The molecular weight distribution (Mw / Mn) of the (meth) acrylic polymer (A) is preferably 20 or less, more preferably 1.5 to 18, and even more preferably 1.8 to 15.

The glass transition temperature (Tg) of the (meth) acrylic polymer (A) is preferably less than 0 ° C., more preferably −80 to −10 ° C., still more preferably −70 to −20 ° C. The Tg of the (meth) acrylic polymer (A) can be determined by the Fox formula, and the Tg of the homopolymer formed from each monomer in the Fox formula is described in Polymer Handbook Fourth Edition (Wiley-Interscience 2003). The value can be adopted.

<Manufacturing of (meth) acrylic polymer (A)>
The (meth) acrylic polymer (A) can be produced by polymerizing or copolymerizing the above-mentioned monomer components. The copolymer may be any of a random copolymer, a block copolymer and a graft copolymer, but a random copolymer is preferable. The (meth) acrylic polymer (A) can be produced by, for example, a conventionally known polymerization method such as a solution polymerization method, a massive polymerization method, an emulsion polymerization method, or a suspension polymerization method, and among these, the solution polymerization method is preferable. ..

Specifically, in the solution polymerization method, a monomer component, a polymerization initiator and other components such as a chain transfer agent and a polymerization solvent are charged in the reaction vessel, and the reaction start temperature is set to 40 to 100 ° C. The reaction system is maintained at a temperature of 50 to 90 ° C. and reacted for 2 to 20 hours. The reaction is carried out in an atmosphere of an inert gas such as nitrogen gas. Further, at least one selected from a monomer component, a polymerization initiator, a chain transfer agent and a polymerization solvent may be additionally added during the polymerization reaction.

Examples of the polymerization initiator include thermal polymerization initiators such as azo-based initiators and peroxide-based polymerization initiators.
Examples of the azo-based initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobis (2-). Cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbo) Nitrile), 2- (carbamoylazo) isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'- Azobis (N, N'-dimethyleneisobutyramidine), 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2'-azobis (isobutylamide) dihydrate, 4 , 4'-azobis (4-cyanopentanoic acid), 2,2'-azobis (2-cyanopropanol), dimethyl-2,2'-azobis (2-methylpropionate) and the like.

Examples of the peroxide-based polymerization initiator include t-butyl hydroperoxide, cumene hydrooxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, and di-i-propylperoxydicarbonate. , Di-2-ethylhexyl peroxydicarbonate, t-butylperoxypivalate, 2,2-bis (4,5-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,5-bis) Di-t-amylperoxycyclohexyl) propane, 2,2-bis (4,5-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,5-di-α-cumylperoxycyclohexyl) ) Propane, 2,2-bis (4,5-di-t-butylperoxycyclohexyl) butane, 2,2-bis (4,5-di-t-octylperoxycyclohexyl) butane.

The polymerization initiator may be used alone or in combination of two or more.

In the production of the (meth) acrylic polymer (A), the amount of the polymerization initiator used is usually 0.001 to 5 parts by mass, preferably 0.005 to 3 parts by mass with respect to 100 parts by mass of the total monomer components. Is.

Examples of the polymerization solvent include aromatic hydrocarbons such as benzene, toluene and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane and n-octane; cyclopentane, cyclohexane, cycloheptane and cyclo. Alicyclic hydrocarbons such as octane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, diphenyl ether; chloroform, carbon tetrachloride, 1,2- Halogenated hydrocarbons such as dichloroethane and chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate and methyl propionate; ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone and cyclohexanone; N, N-dimethylformamide, N , N-dimethylacetamide, amides such as N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile; sulfoxides such as dimethylsulfoxide and sulfolanes.
The polymerization solvent may be used alone or in combination of two or more.

<Synthetic hydrocarbon adhesive resin (B)>
The pressure-sensitive adhesive composition of the present invention contains a synthetic hydrocarbon-based pressure-sensitive adhesive resin (B). The synthetic hydrocarbon-based tackifier resin (B) is not particularly limited as long as it is a petroleum-based resin and can impart tackiness to the pressure-sensitive adhesive composition.

From the viewpoint of heat resistance, the molecular weight of the synthetic hydrocarbon-based tackifier resin (B) is preferably 800 or more, more preferably 1000 or more, and further preferably 1100 or more. When the petroleum-based adhesive resin is a polymer, it represents the weight average molecular weight (Mw).

The softening point of the synthetic hydrocarbon-based tackifier resin (B) is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, and further preferably 90 ° C. or higher from the viewpoint of heat resistance.

Examples of the synthetic hydrocarbon-based tackifier resin (B) include petroleum resin, styrene-based resin, and kumaron-inden resin. Above all, a styrene resin is preferable from the viewpoint of compatibility (appearance) with an acrylic polymer containing n-butyl (meth) acrylate as a main component.

<Petroleum resin>
Petroleum resins include aliphatic (C5 series) petroleum resins, aromatic (C9 series) petroleum resins, aliphatic / aromatic copolymerized (C5 / C9 series) petroleum resins, and hydrogenated additives thereof (for example, aromatics). An alicyclic petroleum resin obtained by adding hydrogen to a group petroleum resin) and the like. Specific examples of petroleum resins include Quinton A, B, R, CX series (all manufactured by Nippon Zeon Corporation), Alcon P-90, Alcon P-100, Alcon P-115, Alcon P-125, and Alcon. P-135, Alcon M-90, Alcon M-100, Alcon M-115 (all manufactured by Arakawa Chemical Industry Co., Ltd.), Nisseki Neopolymer L-90, 120, 130, 140, 150, 170S, S, T -REZ HA085, HA103, HA105, HA125 (all manufactured by JXTG Energy Co., Ltd.) can be mentioned.

<Styrene resin>
Examples of the styrene-based tackifier resin include styrene-based polymers, α-methylstyrene-based polymers, styrene- (α-methylstyrene) -based copolymers, styrene-aliphatic hydrocarbon-based copolymers, and styrene- (α). -Methylstyrene) -aliphatic hydrocarbon-based copolymer, styrene-aromatic hydrocarbon-based copolymer and the like can be mentioned. More specifically, for example, FMR-0150, FTR-0100, FTR-2120, FTR-2140, FTR-6100, FTR-6110, FTR-6125, FTR-7100, FTR-8100, FTR-8120 (or more, (Mitsui Chemicals, Inc.). Further, YS resin SX-100 (manufactured by Yasuhara Chemical Co., Ltd.) can also be mentioned.

<Kumaron-Inden resin>
Specific examples of the Kumaron-inden resin include Kumaron G-90, V-120, and L-5 (all manufactured by Nikko Kagaku Co., Ltd.).

The synthetic hydrocarbon-based tackifier resin (B) may be used alone or in combination of two or more, but preferably contains at least one styrene-based resin.

A tackifier resin other than the synthetic hydrocarbon-based tackifier resin (B) can be used as long as the characteristics are not impaired. Examples of the tackifier resin other than the synthetic hydrocarbon-based tackifier resin include a rosin-based tackifier resin, a terpene-based tackifier resin, and a terpene phenol-based tackifier resin.

In the pressure-sensitive adhesive composition of the present invention, the lower limit of the content of the synthetic hydrocarbon-based pressure-sensitive adhesive resin (B) is relative to the total amount of the (meth) acrylic polymer (A) and the synthetic hydrocarbon-based pressure-sensitive adhesive resin (B). It is 40% by mass or more. The upper limit of the content of the synthetic hydrocarbon-based tackifier resin (B) is 60% by mass or less with respect to the total amount of the (meth) acrylic polymer (A) and the synthetic hydrocarbon-based tackifier resin (B). Yes, preferably 55% by mass or less. If it is 40% by mass or more, the physical properties of a predetermined adhesive force can be exhibited, and if it is 60% by mass or less, the uniformity of the pressure-sensitive adhesive component is maintained. When a plurality of synthetic hydrocarbon-based tackifier resins (B) are used, the composition of the pressure-sensitive adhesive composition may be adjusted so that the total of the tackifier resins falls within the above range.

<Crosslinking agent>
The cross-linking agent contained in the pressure-sensitive adhesive composition is one having reactivity with the cross-linking group of the (meth) acrylic polymer (A).

Examples of the cross-linking agent include isocyanate compounds, epoxy compounds, and metal chelate compounds.

As the isocyanate compound, as the isocyanate compound, an isocyanate compound having 2 or more isocyanate groups in one molecule is usually used, preferably 2 to 8, and more preferably 3 to 6. When the number of isocyanate groups is within the above range, it is preferable in terms of the cross-linking reaction efficiency between the (meth) acrylic polymer (A) and the isocyanate compound, and in terms of maintaining the flexibility of the pressure-sensitive adhesive layer.

Examples of the diisocyanate compound having 2 isocyanate groups in one molecule include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. Examples of the aliphatic diisocyanate include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and 2,2,4-trimethyl. Examples thereof include aliphatic diisocyanates having 4 to 30 carbon atoms such as -1,6-hexamethylene diisocyanate. Examples of the alicyclic diisocyanate include isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate. Diisocyanate can be mentioned. Examples of the aromatic diisocyanate include aromatic diisocyanates having 8 to 30 carbon atoms such as phenylenediocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate.

Examples of the isocyanate compound having 3 or more isocyanate groups in one molecule include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates. Specific examples thereof include 2,4,6-triisocyanate toluene, 1,3,5-triisocyanatebenzene, and 4,4', 4 "-triphenylmethane triisocyanate.

Examples of the isocyanate compound include multimers (for example, dimer or trimer, biuret, isocyanurate) and derivatives (for example, polyhydric alcohol) of the above isocyanate compound having 2 or 3 or more isocyanate groups. Addition reaction products with two or more molecules of diisocyanate compounds) and polymers. Examples of the polyhydric alcohol in the derivative include trihydric or higher alcohols such as trimethylolpropane, glycerin, and pentaerythritol as low molecular weight polyhydric alcohols; and examples of high molecular weight polyhydric alcohols include polyether polyols. Examples thereof include polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprene polyols.

Examples of such isocyanate compounds include trimer of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, hexamethylene diisocyanate or biuret or isocyanurate of tolylene diisocyanate, trimethyl propane and tolylene diisocyanate or xylylene diisocyanate. Reaction products with (for example, three-molecule adduct of tolylene diisocyanate or xylylene diisocyanate), reaction products of trimethylolpropane and hexamethylene diisocyanate (for example, three-molecule adduct of hexamethylene diisocyanate), polyether polyisocyanate, Examples include polyester polyisocyanate.

Among the isocyanate compounds, xylylene diisocyanate-based and hexamethylene diisocyanate-based cross-linking agents are preferable from the viewpoint of refractory yellowing, and tolylene diisocyanate-based cross-linking agents are preferable from the viewpoint of stress relaxation. Examples of the xylylene diisocyanate-based cross-linking agent include xylylene diisocyanate and its multimers, derivatives and polymers; examples of the hexamethylene diisocyanate-based cross-linking agent include hexamethylene diisocyanate and its multimers, derivatives and polymers. Examples of the tolylene diisocyanate-based cross-linking agent include tolylene diisocyanate and its multimers, derivatives, and polymers.

Examples of the epoxy compound include compounds having two or more epoxy groups in the molecule, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexane. Didiol diglycidyl ether, trimethylolpropan triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N', N'-tetraglycidyl-m-xylylene diamine, 1,3-bis (N, N'- Diamine glycidyl aminomethyl).

As the metal chelate compound, for example, alkoxide, acetylacetone, ethyl acetoacetate and the like are coordinated with polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium and zirconium. Examples include compounds. Specific examples thereof include aluminum isopropylate, aluminum secondary butyrate, aluminum ethyl acetoacetate / diisopropirate, aluminum tris ethyl acetoacetate, and aluminum tris acetyl acetonate.

The cross-linking agent may be used alone or in combination of two or more.

In the pressure-sensitive adhesive composition of the present invention, the cross-linking agent is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass in total of the (meth) acrylic polymer (A) and the synthetic hydrocarbon-based pressure-sensitive adhesive resin (B). More preferably 0.05 to 3 parts by mass, still more preferably 0.1 to 2.5 parts by mass. In such an embodiment, excellent adhesive properties can be realized.

<Additives>
The pressure-sensitive adhesive composition of the present invention may contain various additives such as a silane coupling agent, an organopolysiloxane compound, a pigment, a flame retardant, a plasticizer, an antioxidant, a lubricant, and a filler. The content of the additive is not particularly limited, but the content should be within a range that does not impair the characteristics of the double-sided pressure-sensitive adhesive sheet and the pressure-sensitive adhesive composition used for the double-sided pressure-sensitive adhesive sheet of the present invention.
Above all, by appropriately containing a silane coupling agent in the pressure-sensitive adhesive composition of the present invention, it is possible to impart adhesion to a polar adherend (glass, SUS, etc.), thereby improving curved surface adhesiveness and the like. be able to. When a silane coupling agent is added, it can be contained in an amount of more than 0% by mass and 3% by mass or less, preferably 2% by mass or less, and more preferably 0.01 to 1% by mass, based on the entire pressure-sensitive adhesive composition. % Or less can be contained. Although a flame retardant may be contained, less than 24 parts by mass is preferable with respect to 100 parts by mass in total of the (meth) acrylic polymer (A) and the synthetic hydrocarbon-based tackifier resin (B).

<Organic solvent>
The pressure-sensitive adhesive composition of the present invention may contain an organic solvent in order to adjust the coatability. Examples of the organic solvent include the polymerization solvent described in the column of production conditions for the (meth) acrylic polymer (A). The content of the organic solvent in the pressure-sensitive adhesive composition is usually 30 to 90% by mass, preferably 40 to 90% by mass.

[Adhesive tape]
The pressure-sensitive adhesive tape of the present invention is composed of a base material and a pressure-sensitive adhesive layer formed on at least one of both sides of the base material. Therefore, the adhesive tape of the present invention has a structure of at least two layers of a base material and an adhesive layer, and when the pressure-sensitive adhesive layers are formed on both sides of the base material, it has a structure of at least three layers. There is. A release film may be attached to the surface of the pressure-sensitive adhesive layer that is not in contact with the base material.

<Base material>
The adhesive tape of the present invention contains a base material. The thickness of the base material used for the adhesive tape of the present invention is not particularly limited, but when the adhesive tape is thinned, a thickness of 1 to 12 μm is preferable. If it is 1 μm or more, an appropriate sheet strength can be obtained, and if it is 12 μm or less, adhesion progress can be suppressed.
Further, in applications where it is preferable that the total thickness of the adhesive tape is thin, it is preferable that the base material is thin. In that case, the thickness of the base material is preferably 10 μm or less, and particularly preferably 6 μm or less.

Examples of the base material and the release film include polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP), and the like. Examples thereof include plastic films such as ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), polyamide (nylon), polyimide and polyvinyl chloride (PVC). Further, examples of the base material include glass, paper, non-woven fabric and the like. When the adhesive tape is thinned, the base material is preferably a plastic film because it is smooth, and the base material is more preferably PET from the viewpoint of strength and ease of handling.
When the adhesive tape of the present invention is used as a light-shielding tape, a base material containing a black color material such as a black pigment or a white color material such as a white pigment dispersedly contained may be used.

<Adhesive layer>
The pressure-sensitive adhesive layer provided on at least one surface of the base material can be formed from the pressure-sensitive adhesive composition of the present invention. When the pressure-sensitive adhesive layers on both sides of the base material are provided, they may be the same or different from each other.
The thickness of the pressure-sensitive adhesive layer is not particularly limited, but when the pressure-sensitive adhesive tape is thinned, a thickness of 1 to 12 μm is preferable. If it is 1 μm or more, an adhesive tape having an appropriate adhesive strength can be obtained, and if it is 12 μm or less, the adhesive progress can be suppressed.
When a thin-film adhesive tape is required as the tape for fixing the electric member, the total thickness of the adhesive tape excluding the release film is preferably 25 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less. be.
Further, it is preferable that the pressure-sensitive adhesive layer occupies 40% or more of the total thickness of the pressure-sensitive adhesive tape excluding the release film. By doing so, it is possible to secure sufficient adhesive strength of the adhesive tape.

The gel fraction of the pressure-sensitive adhesive layer is preferably 10 to 98% by mass, more preferably 20 to 90% by mass, and further preferably 30 to 85% by mass from the viewpoints of cohesive force, adhesive force described later, and suitability for reattachment. %.

[Use]
As described above, the adhesive tape of the present invention is thin and has strong adhesive strength, so that it can be used for various purposes. For example, the heat-dissipating sheet or the light-shielding tape can be attached to the target article by using the adhesive tape of the present invention. Hereinafter, the heat radiating sheet and the light-shielding tape will be described.

-Heat dissipation sheet By installing the heat dissipation sheet in a local high temperature area, heat can be dissipated to the entire surface of OA equipment and electronic equipment. Examples of the graphite sheet used for the heat radiating sheet include a natural graphite sheet obtained by forming a natural graphite powder into a sheet, an artificial graphite sheet obtained by heat-treating a polymer film, and the like.
Examples of the polymer film include polyimide, polyamide, polyoxadiazole, polybenzothiazole, polybenzobisthiazole, polybenzoxazole, polybenzobisoxazole, polyparaphenylene vinylene, polybenzimidazole, polybenzobisimidazole, and poly. Examples thereof include a film made of thiazole or the like.
The thickness of the graphite sheet is preferably 10 to 100 μm, more preferably 15 to 50 μm. By setting the thickness of the graphite sheet within the above range, it is suitably used for fixing parts of OA equipment and electronic equipment.

-Light-shielding tape The light-shielding tape can prevent problems caused by leaked light by being used, for example, for attaching a non-self-luminous display unit such as a liquid crystal display module unit to a backlight unit.

<Manufacturing method of adhesive tape>
The adhesive tape of the present invention can be manufactured as follows. The case where the adhesive layer is provided on both sides will be described as an example.
The pressure-sensitive adhesive composition of the present invention is applied to one side of the release film so that the thickness after drying becomes a predetermined thickness, and the film is usually dried at 60 to 100 ° C. for 1 to 10 minutes to remove the solvent. Then, the obtained pressure-sensitive adhesive layer is bonded to one side of the base material (referred to as the first side of the base material).

Next, the pressure-sensitive adhesive composition is applied to one side of another release film so that the thickness after drying becomes a predetermined thickness. Then, the pressure-sensitive adhesive layer obtained by drying at 60 to 100 ° C. for 1 to 10 minutes to remove the solvent is the side on which the pressure-sensitive adhesive layer of the base material is not bonded (referred to as the second surface of the base material). A double-sided adhesive tape is manufactured by sticking to.
The coating method is not particularly limited, and a conventionally known method can be used. Examples of the method of applying the pressure-sensitive adhesive composition include a method using a roll coater, a fountain coater, a lip coater, a knife coater, a die coater, a gravure coater, a reverse coater, a lip coater, a curtain coater, a slit die coater and the like. ..
The pressure-sensitive adhesive layer formed on the first surface and the pressure-sensitive adhesive layer formed on the second surface may be the same or different.

Examples will be described below, but the present invention is not limited to the examples.

(Production Example 1: Production of (meth) acrylic polymer (A-1))
80 parts by mass of n-butyl acrylate (n-BA), 17.9 parts by mass of 2-ethylhexyl acrylate (2EHA), 2-hydroxyethyl acrylate in a reactor equipped with a stirrer, reflux condenser, thermometer and nitrogen introduction tube. 0.1 part by mass of (2-HEA), 2 parts by mass of acrylic acid (AA), and 150 parts by mass of ethyl acetate were charged, and the temperature was raised to 70 ° C. while introducing nitrogen gas. Next, 0.03 part by mass of 2,2'-azobis (methyl isobutyrate) was added, and the reaction was carried out for 6 hours while repeating heating and cooling so that the temperature of the contents in the flask could be maintained at 70 to 71 ° C. rice field. After completion of the reaction, 20 parts by mass of ethyl acetate was further added to obtain a (meth) acrylic polymer (A-1) having a weight average molecular weight (Mw) of 1 million.

(Production Example 2: Production of (meth) acrylic polymer (A-2))
The same procedure as in Production Example 1 was carried out except that 2,2'-azobis (methyl isobutyrate) was changed to 0.06 part, and a (meth) acrylic polymer (A-2) having a weight average molecular weight (Mw) of 700,000 was added. Obtained.

(Production Example 3: Production of (meth) acrylic polymer (A-3))
The same procedure as in Production Example 1 was carried out except that n-BA was changed to 70 parts by mass and 2EHA was changed to 27.9 parts by mass to obtain a (meth) acrylic polymer (A-3) having a weight average molecular weight (Mw) of 1 million. ..

(Production Example 4: Production of (meth) acrylic polymer (A-4))
The same procedure as in Production Example 1 was carried out except that n-BA was changed to 90 parts by mass and 2EHA was changed to 7.9 parts by mass to obtain a (meth) acrylic polymer (A-4) having a weight average molecular weight (Mw) of 1 million. ..

(Production Example 5: Production of (meth) acrylic polymer (A-5))
The same procedure as in Production Example 1 was carried out except that 2,2'-azobis (methyl isobutyrate) was changed to 0.08 part, and a (meth) acrylic polymer (A-5) having a weight average molecular weight (Mw) of 500,000 was added. Obtained.

(Production Example 6: Production of (meth) acrylic polymer (A-6))
The same procedure as in Production Example 1 was carried out except that n-BA was changed to 50 parts by mass and 2EHA was changed to 47.9 parts by mass to obtain a (meth) acrylic polymer (A-6) having a weight average molecular weight (Mw) of 1 million. ..

(Example 1)
80 parts by mass ((A)) of the synthetic hydrocarbon-based tackifier resin (B) (FTR-6100: manufactured by Mitsui Chemicals, Inc.) with respect to 100 parts by mass of the solid content of the (meth) acrylic polymer (A-1). Ratio of (B) to the total of B): 44% by mass), isocyanate cross-linking agent (L-45: manufactured by Soken Kagaku Co., Ltd.), (meth) acrylic polymer (A-1) and synthetic hydrocarbon-based tackifier resin ( 1.5 parts by mass (solid content) was mixed with respect to the total with B) to obtain a pressure-sensitive adhesive composition 1.

The pressure-sensitive adhesive composition 1 was coated on a polyethylene terephthalate (PET) release film that had been peeled off so as to have a thickness of 2 μm after drying. The coated sheet is dried at 80 ° C. for 3 minutes, transferred to both sides of a 2 μm-thick PET film substrate, and aged for 7 days in an environment of room temperature of 23 ° C. and humidity of 50% to obtain a double-sided tape. rice field.
Various characteristics of the obtained adhesive tape were measured and shown in Table 1.

(Examples 2 to 4, Examples 6 to 8 and Comparative Examples 1 to 5)
The same procedure as in Example 1 was carried out except that the type of the (meth) acrylic polymer (A), the type of the synthetic hydrocarbon-based tackifier resin (B), and the amount used were changed as shown in Table 1, and the pressure-sensitive adhesive composition was changed. Objects 2 to 4, 6 to 13 were obtained.
Various characteristics of the obtained adhesive tape were measured and shown in Table 1.

(Example 5)
The same procedure as in Example 1 was carried out except that 0.2 parts by mass of a silane coupling agent (KBM-403: manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 parts of the resin solid content to obtain the pressure-sensitive adhesive composition 5. rice field.
Various characteristics of the obtained adhesive tape were measured and shown in Table 1.

(Example 9)
The pressure-sensitive adhesive composition 1 was applied onto a peel-treated PET peeling film so as to have a thickness of 25 μm after drying. The coated sheet was dried at 80 ° C. for 3 minutes, transferred to a PET film substrate having a thickness of 25 μm, and aged for 7 days in an environment of room temperature of 23 ° C. and humidity of 50% to obtain a single-sided tape.
Various characteristics of the obtained adhesive tape were measured and shown in Table 2.

(Comparative Example 6)
A single-sided tape was obtained in the same manner as in Example 9 except that the pressure-sensitive adhesive composition was changed to 13.
Various characteristics of the obtained adhesive tape were measured and shown in Table 2.

<Measurement / evaluation>
The measurement method is described below.
(Weight average molecular weight (Mw))
For the (meth) acrylic polymer (A), the weight average molecular weight (Mw) in terms of standard polystyrene was determined by the gel permeation chromatography (GPC) method under the following conditions.
-Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)
-GPC column configuration: The following 5-column column (all manufactured by Tosoh Corporation)
(1) TSK-GELHXL-H (guard column)
(2) TSK-GELG7000HXL
(3) TSK-GELGMHXL
(4) TSK-GELGMHXL
(5) TSK-GELG2500HXL
・ Sample concentration: ^{Dilute with tetrahydrofuran so as to be 1.0 mg / cm 3}・ Mobile phase solvent: Tetrahydrofuran ・ Flow rate: 1.0 cm ³ / min
-Column temperature: 40 ° C

(Adhesive force)
In the case of the double-sided adhesive tape, after peeling off one PET release film, a PET film having a thickness of 6 μm was lined on the exposed one adhesive layer surface and cut into 25 mm × 70 mm to obtain a test piece. In the case of single-sided tape, it was made into a test piece only by cutting it into 25 mm × 70 mm. The remaining PET release film was peeled off from this test piece under the conditions of 23 ° C. and 50% RH, and stainless steel (SUS) was bonded to the exposed adhesive layer surface using a 2 kg roller (bonded area 25 mm × 70 mm). ..
Twenty minutes after the bonding, the test piece was peeled from the SUS plate in the 180 ° direction at a speed of 300 mm / min, and the adhesive strength of the pressure-sensitive adhesive layer was measured.

(Holding power)
In the case of the double-sided adhesive tape, the PET release film on one surface was peeled off, the exposed adhesive layer surface was lined with a PET film having a thickness of 100 μm, and the test piece was cut into a width of 20 mm. In the case of single-sided tape, it was made into a test piece only by cutting it to 20 mm. Then, the PET release film on the other surface was peeled off, the exposed other pressure-sensitive adhesive layer surface was attached to a SUS plate, and pressure-bonded using a 2 kg roller. The sticking area was 20 mm × 20 mm. Twenty minutes after application, a load of 1 kg was applied in a direction parallel to the pressure-sensitive adhesive layer surface at 80 ° C. and dry conditions, and the distance (mm) of deviation from the original position after 1 hour was measured. In the table, "nc" means that the amount of deviation is equal to or less than the lower limit of measurement.

(Constant load peelability)
In the case of the double-sided adhesive tape, after peeling off one PET release film, a PET film having a thickness of 6 μm was lined on the exposed one adhesive layer surface, and the test piece was cut into a size of 20 mm × 50 mm to prepare a test piece. In the case of a single-sided tape, a test piece was prepared only by cutting into a size of 20 mm × 50 mm. The PET release film remaining on this test piece was peeled off, attached to a SUS plate whose surface was polished and cleaned with a solvent, a load of 200 g was applied in the direction of 90 ° at a temperature of 80 ° C., and the peeling distance when left for 60 minutes. The time to (mm) or drop was measured. In addition, "X'↓" in the table means that it fell within 60 minutes, and it means that it fell within "X" minutes.

(exterior)
In the case of the double-sided adhesive tape, after peeling off one PET release film, a PET film having a thickness of 6 μm was lined on the exposed one adhesive layer surface, and the test piece was cut into a size of 20 mm × 50 mm to prepare a test piece. In the case of a single-sided tape, a test piece was prepared only by cutting into a size of 20 mm × 50 mm. The PET release film of the test piece was peeled off and bonded to glass to prepare a test piece. After the test piece was autoclaved (50 ° C., 5 atm, 20 minutes), the appearance of the test piece was visually evaluated. Colorless and transparent are marked with ◯, yellow and transparent with some turbidity are marked with Δ, and those with clear color are marked with x.

(Curved surface adhesiveness)
After peeling off one PET release film on the double-sided adhesive tape, a PET film having a thickness of 100 μm was lined on the exposed one adhesive layer surface, and the test piece was cut into a size of 20 mm × 60 mm to prepare a test piece. The PET release film remaining on the test piece was peeled off, and the surface was polished and attached to a SUS rod having a diameter of 24 mm and cleaned with a solvent so that the long side of the test piece was in the circumferential direction. I kept the time. After 24 hours, the average distance of peeling lengths from both ends was measured. Those with no peeling were marked with ◯, those with peeling of 5 mm or less were marked with Δ, and those with peeling greater than 5 mm were marked with x.

In Comparative Examples 1 and 2, a rosin-based tackifier resin was used, and the adhesive strength, the holding power, and the constant load peelability were lower than those of Examples 1, 6, 7, and 8. Further, in Comparative Example 2, since the amount of the tackifier resin added was the same as in Examples 1, 6, 7, and 8, the compatibility was worse, the sheet appearance was poor, and the curved surface adhesiveness was also lowered.
In Comparative Example 3, the same synthetic hydrocarbon-based tackifier resin as in Example 1 is used, but the content of the synthetic hydrocarbon-based tackifier resin is (meth) acrylic polymer (A) and the synthetic hydrocarbon-based tackifier resin. Since it was less than 40% by mass with respect to the total amount of (B), the constant load peelability was excellent as compared with Example 1, but the adhesive strength and the curved surface adhesiveness were lowered.
In Comparative Example 4, the adhesive strength and the constant load peelability were lowered, and the curved surface adhesiveness was also lowered as compared with Examples 1 and 2 in which the molecular weight of the (meth) acrylic polymer (A) was less than 700,000.
In Comparative Example 5, the n-butyl acrylate content was less than 70% by mass, and the adhesive strength, holding power, and constant load peelability were lower than those of Examples 1, 3 and 9.
In Example 9 and Comparative Example 6, the pressure-sensitive adhesive composition used in Example 1 and Comparative Example 5 was applied to a single-sided tape. Adhesive strength, holding power, and constant load peelability were reduced as compared with Example 9.

Claims (10)

A pressure-sensitive adhesive composition containing a (meth) acrylic polymer (A) having a weight average molecular weight of 700,000 or more and a synthetic hydrocarbon-based pressure-sensitive adhesive resin (B).
The (meth) acrylic polymer (A) is a polymer obtained by polymerizing a monomer containing 60% by mass or more of n-butyl (meth) acrylate (a1).
The content of the synthetic hydrocarbon-based tackifier resin (B) is 40% by mass or more and 60% by mass or less with respect to the total mass of the (meth) acrylic polymer (A) and the synthetic hydrocarbon-based tackifier resin (B). A pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition according to claim 1, wherein the synthetic hydrocarbon-based pressure-sensitive adhesive resin (B) is a styrene-based resin. The pressure-sensitive adhesive composition according to claim 1 or 2, which comprises a cross-linking agent. Any of claims 1 to 3, wherein the (meth) acrylic polymer (A) is a polymer obtained by polymerizing a monomer containing a (meth) acrylic monomer containing 80% by mass or more of n-butyl (meth) acrylate. The pressure-sensitive adhesive composition according to item 1. The pressure-sensitive adhesive composition according to any one of claims 1 to 4, which contains 0.01 to 3.0 parts by mass of a silane coupling agent with respect to 100 parts by mass of the resin solid content of the pressure-sensitive adhesive composition. thing. An adhesive tape comprising an adhesive layer comprising the adhesive composition according to any one of claims 1 to 5. The adhesive tape according to claim 6, wherein adhesive layers are provided on both sides of the base material. The adhesive tape according to claim 6 or 7, wherein the total thickness excluding the release film is 25 μm or less. The adhesive tape according to any one of claims 6 to 8, wherein the adhesive layer occupies 40% or more of the total thickness excluding the release film. The adhesive tape according to any one of claims 6 to 9, which is used for fixing a member of an electronic device.