JP2012067279A - Acrylic adhesive composition, acrylic adhesive layer and acrylic adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic adhesive tape having improved adhesiveness to an adherend with low polarity.SOLUTION: An acrylic adhesive composition is provided, containing: 100 pts.mass of an acrylic polymer (A); 1 to 70 pts.mass of a (meth)acrylic polymer (B) having a weight average molecular weight of at least 1,000 or more and less than 30,000; and 1 to 50 pts.mass of a hydrogenated tackifier resin (C). The meth(acrylic) polymer (B) is a polymer having a lower weight average molecular weight than the acrylic polymer (A) acting as an adhesive composition, and functions as a tackifier resin together with the hydrogenated tackifier resin (C).

Description

  The present invention relates to an acrylic pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive layer having the composition, and an acrylic pressure-sensitive adhesive tape.

  Conventionally, an acrylic pressure-sensitive adhesive tape having an acrylic pressure-sensitive adhesive layer has excellent adhesive properties such as adhesive strength, repulsion resistance, and retention properties (cohesive strength), and has heat resistance, light resistance, weather resistance, oil resistance, etc. Widely used because of its excellent aging resistance. In particular, acrylic pressure-sensitive adhesive tapes having such characteristics are widely used as bonding materials in various industrial fields such as home appliances, building materials, and automobile interior / exterior materials. Therefore, various adhesive materials such as metal materials such as stainless steel and aluminum, various plastic materials such as polyethylene, polypropylene, polystyrene, ABS, (meth) acrylic resin, polycarbonate resin, and glass materials are applied to the acrylic adhesive tape. It is required to adhere to the body (joining object) with high reliability.

  As a technique for improving the adhesion of an acrylic pressure-sensitive adhesive tape to an adherend, a method of adding a tackifier resin (tackifier) to the acrylic pressure-sensitive adhesive composition constituting the acrylic pressure-sensitive adhesive layer is known. Patent Documents 1 and 2 disclose an acrylic pressure-sensitive adhesive composition in which rosin or hydrogenated petroleum resin is added as a tackifier resin to an acrylic polymer.

JP-A-6-207151 Japanese National Patent Publication No. 11-504054

  Acrylic adhesive tapes are always required to have improved adhesion to adherends, especially for polyolefin resins such as polyethylene and polypropylene, which are often used in home appliances, building materials, automotive interior and exterior materials, etc. There is a strong demand for improvement in adhesion to representative low-polar adherends. On the other hand, when the above-mentioned acrylic pressure-sensitive adhesive composition to which a tackifying resin such as rosin is added does not sufficiently meet the demand for improving the adhesion of the acrylic pressure-sensitive adhesive tape to the low-polar adherend. was there.

  This invention is made | formed in view of such a subject, The objective is to provide the technique which can improve the adhesiveness of an acrylic adhesive tape.

  One embodiment of the present invention is an acrylic pressure-sensitive adhesive composition. The acrylic pressure-sensitive adhesive composition includes 100 parts by mass of an acrylic polymer (A), 1 to 70 parts by mass of a (meth) acrylic polymer (B) having a weight average molecular weight of 1000 or more and less than 30000, and a hydrogenated type And 1 to 50 parts by mass of a tackifier resin (C).

  According to the acrylic pressure-sensitive adhesive composition of this aspect, the adhesive force of the acrylic pressure-sensitive adhesive tape to the adherend including the low-polar adherend can be improved.

  In the acrylic pressure-sensitive adhesive composition of the above aspect, the glass transition temperature of the (meth) acrylic polymer (B) may be 0 ° C. or higher and 300 ° C. or lower. Further, the (meth) acrylic polymer (B) may include a (meth) acrylic monomer having an alicyclic structure in the side chain as a monomer unit. In this case, the alicyclic hydrocarbon group of the (meth) acrylic monomer having an alicyclic structure may have a bridged ring structure.

一般式（１）式中、Ｒ^３は、２価の有機基である。 Further, the hydrogenated tackifying resin (C) may be a petroleum resin or a terpene resin. Moreover, 80-200 degreeC may be sufficient as the softening point of hydrogenation type tackifying resin (C).
The acrylic polymer (A) has at least one monomer selected from the group consisting of N-vinyl cyclic amide represented by acrylic (1) described in the following general formula and a carboxyl group-containing monomer as a monomer unit. It may contain.

In the general formula (1), R ³ is a divalent organic group.

  Another embodiment of the present invention is an acrylic pressure-sensitive adhesive layer. The said acrylic adhesive layer consists of an acrylic adhesive composition of any aspect mentioned above. In the acrylic pressure-sensitive adhesive layer of this embodiment, 40 to 90% by mass of a solvent-insoluble component may be included.

  Yet another embodiment of the present invention is an acrylic pressure-sensitive adhesive tape. The said acrylic adhesive tape contains the acrylic adhesive layer of any aspect mentioned above.

  According to this invention, the adhesiveness of an acrylic adhesive tape can be improved.

  The acrylic pressure-sensitive adhesive composition according to the present embodiment includes an acrylic polymer (A) as a pressure-sensitive adhesive composition and a (meth) acrylic polymer having a weight average molecular weight of 1000 or more and less than 30000 as a tackifier resin. (B) (hereinafter referred to as (meth) acrylic polymer (B) as appropriate) and hydrogenated tackifying resin (C).

Content of each component in the acrylic adhesive composition which concerns on embodiment is as follows.
Acrylic polymer (A): 100 parts by mass (meth) acrylic polymer (B): 1 to 70 parts by mass Hydrogenated tackifying resin (C): 1 to 50 parts by mass

  Hereinafter, the acrylic polymer (A), the (meth) acrylic polymer (B), and the hydrogenated tackifier resin (C) will be described in detail.

[Acrylic polymer (A)]
The acrylic polymer (A) contains, for example, 50% by mass or more of (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms as a monomer unit. Moreover, the acrylic polymer (A) can be configured such that the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is singly or in combination of two or more. The acrylic polymer (A) can be obtained by polymerizing (for example, solution polymerization, emulsion polymerization, UV polymerization) (meth) acrylic acid alkyl ester together with a polymerization initiator.

  The proportion of the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is 50% by mass or more and 99.9% by mass or less, preferably based on the total amount of monomer components for preparing the acrylic polymer (A). Is 60 mass% or more and 98 mass% or less, More preferably, it is 70 mass% or more and 95 mass% or less.

  Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, Butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) acryl Hexyl acid, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, (meth) Decyl acrylate, Isodecyl (meth) acrylate, Unde (meth) acrylate , Dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate (Meth) acrylic acid C1-20 alkyl esters such as (meth) acrylic acid nonadecyl, (meth) acrylic acid eicosyl [preferably (meth) acrylic acid C2-14 alkyl ester, more preferably (meth) acrylic acid C2- 10 alkyl ester] and the like. In addition, (meth) acrylic acid alkyl ester means acrylic acid alkyl ester and / or methacrylic acid alkyl ester, and “(meth)...” Has the same meaning.

As (meth) acrylic acid ester other than (meth) acrylic acid alkyl ester, for example,
(Meth) acrylic acid ester having an alicyclic hydrocarbon group such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate;
(Meth) acrylic acid ester having an aromatic hydrocarbon group such as phenyl (meth) acrylate;
Examples thereof include (meth) acrylic acid esters obtained from terpene compound derivative alcohols.

  The acrylic polymer (A) may contain other monomer components that can be copolymerized with the (meth) acrylic acid alkyl ester, if necessary, for the purpose of modifying cohesion, heat resistance, crosslinkability, and the like. A copolymerizable monomer). Therefore, the acrylic polymer (A) may contain a copolymerizable monomer together with the (meth) acrylic acid alkyl ester as the main component. As the copolymerizable monomer, a monomer having a polar group can be suitably used.

As a specific example of the copolymerizable monomer,
Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid;
Hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, (meta ) Hydroxyl-containing monomers such as hydroxyalkyl (meth) acrylates such as hydroxylauryl acrylate and (4-hydroxymethylcyclohexyl) methyl methacrylate;
Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride;
Sulphonic acid groups such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid Containing monomers;
Phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate;
(Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, N, N-di N, N-dialkyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) such as (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide Acrylamide, N-butyl (meth) acrylamide, Nn-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-ethylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl ( (Meth) acrylamide, N-methoxyethyl (meta) Acrylamide, N- butoxymethyl (meth) acrylamide, N- acryloyl morpholine, etc. (N- substituted) amide monomers;
Succinimide monomers such as N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- (meth) acryloyl-8-oxyhexamethylenesuccinimide;
Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide;
Itaconimides such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide System monomers;
Vinyl esters such as vinyl acetate and vinyl propionate;
N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N- Vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-2-piperidone, N-vinyl-3-morpholinone N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, Contains nitrogen such as N-vinylisothiazole and N-vinylpyridazine Ring-based monomer;
N-vinylcarboxylic acid amides;
Lactam monomers such as N-vinylcaprolactam;
Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile;
(Meth) acrylic such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate Acid aminoalkyl monomers;
(Meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl, (meth) acrylic acid ethoxyethyl, (meth) acrylic acid propoxyethyl, (meth) acrylic acid butoxyethyl, (meth) acrylic acid ethoxypropyl ;
Styrene monomers such as styrene and α-methylstyrene;
Epoxy group-containing acrylic monomers such as (meth) glycidyl acrylate;
Glycol-based acrylic ester monomers such as (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol;
(Meth) acrylic acid tetrahydrofurfuryl, fluorine atom-containing (meth) acrylate, silicone (meth) acrylate and other heterocyclic rings, halogen atoms, silicon atoms and the like, acrylic ester monomers;
Olefin monomers such as isoprene, butadiene, isobutylene;
Vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether;
Vinyl esters such as vinyl acetate and vinyl propionate;
Aromatic vinyl compounds such as vinyltoluene and styrene;
Olefins or dienes such as ethylene, butadiene, isoprene, isobutylene;
Vinyl ethers such as vinyl alkyl ethers;
Vinyl chloride;
(Meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl;
Sulfonic acid group-containing monomers such as sodium vinyl sulfonate;
Imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide;
Isocyanate group-containing monomers such as 2-isocyanatoethyl (meth) acrylate;
Acryloylmorpholine;
Etc. These copolymerizable monomers can be used alone or in combination of two or more.

一般式（１）式中、Ｒ^３は、２価の有機基である。 Among the nitrogen-containing heterocyclic monomers described above, more preferable monomers can be summarized as N-vinyl cyclic amide represented by the following general formula (1).

In the general formula (1), R ³ is a divalent organic group.

  When the acrylic polymer (A) contains a copolymerizable monomer together with a (meth) alkyl acid alkyl ester as a main component, a carboxyl group-containing monomer can be suitably used. Among these, acrylic acid can be preferably used. The amount of the copolymerizable monomer used is not particularly limited, but is usually 0.1 to 40% by mass of the copolymerizable monomer with respect to the total amount of monomer components for preparing the acrylic polymer (A), preferably May be contained in an amount of 0.5 to 30% by mass, more preferably 1 to 20% by mass.

  By containing 0.1% by mass or more of the copolymerizable monomer, the cohesive force of the acrylic pressure-sensitive adhesive tape or sheet having the pressure-sensitive adhesive layer formed of the acrylic pressure-sensitive adhesive composition is prevented from being lowered, and a high shearing force is obtained. be able to. Moreover, by making content of a copolymerizable monomer into 40 mass% or less, it can prevent that cohesion force becomes high too much and can improve the tuck feeling in normal temperature (25 degreeC).

  Moreover, in order to adjust the cohesion force of the acrylic adhesive composition to form in an acrylic polymer (A), you may contain a polyfunctional monomer as needed.

  Examples of the polyfunctional monomer include (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, and pentaerythritol. Tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate , Trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, poly Ester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di (meth) acrylate. Among these, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. Polyfunctional (meth) acrylate can be used individually or in combination of 2 or more types.

  The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, and the like, but is 0.01 to 3.0% by mass, preferably based on the total amount of monomer components for preparing the acrylic polymer (A). It is added to 0.02 to 2.0% by mass, and more preferably 0.03 to 1.0% by mass.

  When the amount of the polyfunctional monomer used exceeds 3.0% by mass with respect to the total amount of the monomer components for preparing the acrylic polymer (A), for example, the cohesive force of the acrylic pressure-sensitive adhesive composition becomes too high. In some cases, the adhesive strength may decrease. On the other hand, when it is less than 0.01% by mass, for example, the cohesive force of the acrylic pressure-sensitive adhesive composition may be reduced.

<Polymerization initiator>
In the preparation of the acrylic polymer (A), the acrylic polymer (A) is obtained by utilizing a curing reaction by heat or ultraviolet rays using a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator). It can be formed easily. In particular, a photopolymerization initiator can be preferably used because of the advantage that the polymerization time can be shortened. A polymerization initiator can be used individually or in combination of 2 or more types.

  Examples of the thermal polymerization initiator include azo polymerization initiators (for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis ( 2-methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2 -(5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethylene) Isobutylamidine) dihydrochloride, etc.); peroxide-based polymerization initiators (for example, dibenzoyl peroxide, t-butylpermaleate, lauroyl peroxide) ); Redox polymerization initiators, and the like.

  The amount of the thermal polymerization initiator used is not particularly limited as long as it can be conventionally used as a thermal polymerization initiator.

  Although it does not restrict | limit especially as a photoinitiator, For example, a benzoin ether type photoinitiator, an acetophenone type photoinitiator, an alpha-ketol type photoinitiator, an aromatic sulfonyl chloride type photoinitiator, photoactivity Oxime photopolymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, acylphosphine oxide photopolymerization initiator An agent or the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- 1-one [trade name: Irgacure 651, manufactured by BASF Corporation], anisole methyl ether and the like can be mentioned. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone [trade name: Irgacure 184, manufactured by BASF Corp.], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- ( 2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one [trade name: Irgacure 2959, manufactured by BASF Corp.], 2-hydroxy-2-methyl-1-phenyl-propane- 1-one [trade name: Darocur 1173, manufactured by BASF Corporation], methoxyacetophenone, and the like can be given. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropane-1- ON etc. are mentioned. Examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalene sulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime.

  The benzoin photopolymerization initiator includes, for example, benzoin. Examples of the benzyl photopolymerization initiator include benzyl and the like. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like are included.

  Examples of the acylphosphine photopolymerization initiator include bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis ( 2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, bis (2,6-dimethoxybenzoyl) octylphosphine Oxide, bis (2- Toxibenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2-methoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (2-methyl Propan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropane-1- Yl) phosphine oxide, bis (2,4-dimethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide Bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis 2,6-dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2,6 -Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide Bis (2,4,6-trimethylbenzoyl) -2,5-diisopropylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2-methylphenylphosphine oxide, bis (2 4,6-trimethylbenzoyl) -4-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2, 3,5,6-tetramethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide, 2,6-dimethoxybenzoyl-2,4,6-trimethyl Benzoyl-n-butylphosphine oxide, bis (2,4,4 -Trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2,4,6-trimethylbenzoyl) phosphine oxide] Examples include decane and tri (2-methylbenzoyl) phosphine oxide.

  Although the usage-amount of a photoinitiator is not restrict | limited in particular, For example, 0.01-5 mass parts with respect to 100 mass parts of monomer components which prepare an acrylic polymer (A), Preferably 0.05-3 mass parts It is blended in an amount within the range.

  Here, when the usage-amount of a photoinitiator is less than 0.01 mass part, a polymerization reaction may become inadequate. When the usage-amount of a photoinitiator exceeds 5 mass parts, an ultraviolet-ray may not reach the inside of an adhesive layer because a photoinitiator absorbs an ultraviolet-ray. In this case, the polymerization rate is lowered, or the molecular weight of the produced polymer is reduced. And thereby, the cohesive force of the pressure-sensitive adhesive layer to be formed becomes low, and when the pressure-sensitive adhesive layer is peeled off from the film, a part of the pressure-sensitive adhesive layer may remain on the film and the film may not be reused. . In addition, a photopolymerization initiator can be used individually or in combination of 2 or more types.

  In order to adjust the cohesion force, it is also possible to use a crosslinking agent in addition to the above-mentioned polyfunctional monomer. As the crosslinking agent, a commonly used crosslinking agent can be used. For example, epoxy crosslinking agent, isocyanate crosslinking agent, silicone crosslinking agent, oxazoline crosslinking agent, aziridine crosslinking agent, silane crosslinking agent, alkyl etherification A melamine type crosslinking agent, a metal chelate type crosslinking agent, etc. can be mentioned. In particular, an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent can be preferably used.

  Specifically, examples of isocyanate-based crosslinking agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene. Examples include diisocyanate, triphenylmethane triisocyanate, polymethylene polyphenyl isocyanate, and adducts of these with polyols such as trimethylolpropane. Alternatively, a compound having at least one isocyanate group and one or more unsaturated bonds in one molecule, specifically, 2-isocyanatoethyl (meth) acrylate or the like may be used as an isocyanate-based crosslinking agent. Can do.

  Epoxy crosslinking agents include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane tri Examples include glycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N′-diamine glycidylaminomethyl) cyclohexane. be able to.

  In this embodiment, the acrylic polymer (A) is a partial polymer (acrylic polymer syrup) obtained by irradiating a mixture of the monomer component and the polymerization initiator with ultraviolet rays (UV) to partially polymerize the monomer component. ) Can also be prepared. Acrylic polymer syrup is blended with the (meth) acrylic polymer (B) to be described later to prepare an acrylic pressure-sensitive adhesive composition. This pressure-sensitive adhesive composition is applied to a predetermined coated body and irradiated with ultraviolet rays. To complete the polymerization. The weight average molecular weight (Mw) of the acrylic polymer (A) is, for example, 30000 to 5000000.

  In addition, the glass transition temperature (Tg) of acrylic polymer (A) is less than 0 degreeC, Preferably, it is less than -10 degreeC, and is -80 degreeC or more normally.

[(Meth) acrylic polymer (B)]
The (meth) acrylic polymer (B) is a polymer having a weight average molecular weight smaller than that of the acrylic polymer (A), functions as a tackifier resin, and hardly causes polymerization inhibition during UV polymerization. Have The (meth) acrylic polymer (B) contains, for example, (meth) acrylic acid ester as a monomer unit.

Examples of such (meth) acrylic acid esters include:
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate , T-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, (meth ) Octyl acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, (meth) (Meth) acrylic acid alkyl esters such as dodecyl acrylate;
Esters of (meth) acrylic acid with alicyclic alcohols such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate;
(Meth) acrylic acid aryl esters such as phenyl (meth) acrylate and benzyl (meth) acrylate;
(Meth) acrylic acid ester obtained from terpene compound derivative alcohol;
Etc. Such (meth) acrylic acid esters can be used alone or in combination of two or more.

  The (meth) acrylic polymer (B) contains, in addition to the (meth) acrylic acid ester component unit, other monomer components (copolymerizable monomers) copolymerizable with the (meth) acrylic acid ester. It can also be obtained by polymerization.

As other monomer copolymerizable with (meth) acrylic acid ester,
Alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate monomer;
(Meth) acrylic acid alkali metal salts and the like;
Di (meth) acrylic acid ester of ethylene glycol, di (meth) acrylic acid ester of diethylene glycol, di (meth) acrylic acid ester of triethylene glycol, di (meth) acrylic acid ester of polyethylene glycol, di (meta) of propylene glycol ) Di (meth) acrylate monomers of (poly) alkylene glycols such as acrylate esters, di (meth) acrylate esters of dipropylene glycol, di (meth) acrylate esters of tripropylene glycol;
Polyvalent (meth) acrylate monomers such as trimethylolpropane tri (meth) acrylate;
Vinyl esters such as vinyl acetate and vinyl propionate;
Vinyl halide compounds such as vinylidene chloride and 2-chloroethyl (meth) acrylate;
An oxazoline group-containing polymerizable compound such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline;
Aziridine group-containing polymerizable compounds such as (meth) acryloylaziridine, (meth) acrylic acid-2-aziridinylethyl;
Epoxy group-containing vinyl monomers such as allyl glycidyl ether, (meth) acrylic acid glycidyl ether, (meth) acrylic acid-2-ethylglycidyl ether;
(Meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, monoester of (meth) acrylic acid and polypropylene glycol or polyethylene glycol, lactones and (meth) acrylic acid-2-hydroxy Hydroxyl group-containing vinyl monomers such as adducts with ethyl;
Fluorine-containing vinyl monomers such as fluorine-substituted (meth) acrylic acid alkyl esters;
Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride;
Aromatic vinyl compound monomers such as styrene, α-methylstyrene, vinyltoluene;
Reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and monochloro vinyl acetate;
(Meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N An amide group-containing vinyl monomer such as ethylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-acryloylmorpholine;
Succinimide monomers such as N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- (meth) acryloyl-8-oxyhexamethylenesuccinimide;
Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide;
Itaconimides such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide System monomers;
N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N- Vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N-vinylmorpholine, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole Nitrogen-containing heterocyclic monomers such as N-vinylisothiazole and N-vinylpyridazine;
N-vinylcarboxylic acid amides;
Lactam monomers such as N-vinylcaprolactam;
Cyanoacrylate monomers such as (meth) acrylonitrile;
(Meth) acrylic such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate Acid aminoalkyl monomers;
Imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide;
Isocyanate group-containing monomers such as 2-isocyanatoethyl (meth) acrylate;
Organosilicon-containing vinyl monomers such as vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, 2-methoxyethoxytrimethoxysilane;
Hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, (meta ) Hydroxyl-containing monomers such as hydroxyalkyl (meth) acrylates such as hydroxylauryl acrylate and (4-hydroxymethylcyclohexyl) methyl methacrylate;
(Meth) acrylic acid tetrahydrofurfuryl, fluorine atom-containing (meth) acrylate, silicone (meth) acrylate and other heterocyclic rings, halogen atoms, silicon atoms and the like, acrylic ester monomers;
Olefin monomers such as isoprene, butadiene, isobutylene;
Vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether;
Olefins or dienes such as ethylene, butadiene, isoprene, isobutylene;
Vinyl ethers such as vinyl alkyl ethers;
Vinyl chloride;
Other examples include macromonomers having a radical polymerizable vinyl group at the terminal of a monomer obtained by polymerizing a vinyl group. These monomers can be copolymerized with the (meth) acrylic acid ester alone or in combination.

  In the acrylic pressure-sensitive adhesive composition of the present embodiment, examples of the (meth) acrylic polymer (B) include a copolymer of cyclohexyl methacrylate (CHMA) and isobutyl methacrylate (IBMA), cyclohexyl methacrylate (CHMA) and isoform. A copolymer of bornyl methacrylate (IBXMA), a copolymer of cyclohexyl methacrylate (CHMA) and acryloylmorpholine (ACMO), a copolymer of cyclohexyl methacrylate (CHMA) and diethyl acrylamide (DEAA), 1-adamantyl acrylate (ADA) And methyl methacrylate (MMA) copolymer, dicyclopentanyl methacrylate (DCPMA) and isobornyl methacrylate (IBXMA) copolymer, dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA), 1-adamantyl acrylate (ADA) Examples of each homopolymer may be mentioned.

  The (meth) acrylic polymer (B) includes (meth) acrylate, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate in which an alkyl group such as t-butyl (meth) acrylate has a branched structure. Such as (meth) acrylic acid ester with alicyclic alcohol, (meth) acrylic acid aryl ester such as phenyl (meth) acrylate and benzyl (meth) acrylate (meth) It is preferable that an acrylic monomer having a relatively bulky structure typified by acrylate is included as a monomer unit. By giving such a bulky structure to the (meth) acrylic polymer (B), the adhesiveness of the acrylic pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive tape) can be further improved. In particular, those having a ring structure in terms of bulkiness are highly effective, and those having a plurality of rings are more effective. In addition, when UV polymerization is employed in the synthesis of the (meth) acrylic polymer (B) or the preparation of the pressure-sensitive adhesive composition, those having a saturated bond are less likely to cause polymerization inhibition. Preferably, (meth) acrylate having an alkyl group having a branched structure or an ester with an alicyclic alcohol can be suitably used as a monomer constituting the (meth) acrylic polymer (B).

  Furthermore, the (meth) acrylic polymer (B) may contain, for example, a (meth) acrylic monomer having a tricyclic or higher alicyclic structure as a monomer unit. Adhesion of acrylic pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive tape) is further improved by giving (meth) acrylic polymer (B) a more bulky structure such as a tricyclic or higher alicyclic structure. Can be made. In particular, the adhesive force with respect to a low polarity adherend such as polypropylene can be more remarkably improved. The (meth) acrylic polymer (B) may be a homopolymer of a (meth) acrylic monomer having this tricyclic or higher alicyclic structure, or has a tricyclic or higher alicyclic structure. It may be a copolymer of a (meth) acrylic monomer and the (meth) acrylic acid ester monomer or a copolymerizable monomer.

The (meth) acrylic monomer is, for example, a (meth) acrylic acid ester represented by the following general formula (2).
CH ₂ = C (R ¹ ) COOR ² (2)
[In Formula (2), R ¹ is a hydrogen atom or a methyl group, and R ² is an alicyclic hydrocarbon group having a tricyclic or higher alicyclic structure]

また、このような橋かけ環構造を有する三環以上の脂環式構造を持つ（メタ）アクリル系モノマーの例としては、ジシクロペンタニルメタクリレート、ジシクロペンタニルアクリレート、ジシクロペンタニルオキシエチルメタクリレート、ジシクロペンタニルオキシエチルアクリレート、トリシクロペンタニルメタクリレート、トリシクロペンタニルアクリレート、１−アダマンチルメタクリレート、１−アダマンチルアクリレート、２−メチル−２−アダマンチルメタクリレート、２−メチル−２−アダマンチルアクリレート、２−エチル−２−アダマンチルメタクリレート、２−エチル−２−アダマンチルアクリレート等の（メタ）アクリル酸エステルを挙げることができる。この（メタ）アクリル系モノマーは、単独であるいは２種以上を組み合わせて使用することができる。 The alicyclic hydrocarbon group preferably has a three-dimensional structure such as a bridged ring structure. Thus, the adhesiveness of the acrylic pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive tape) is obtained by giving the (meth) acrylic polymer (B) a tricyclic or higher alicyclic structure having a bridged ring structure. Can be further improved. In particular, the adhesive force with respect to low polar adherends, such as polyethylene and a polypropylene, can be improved more notably. Examples of the alicyclic hydrocarbon group having a bridged ring structure include a dicyclopentanyl group represented by the following formula (3a), a dicyclopentenyl group represented by the following formula (3b), and the following formula (3c). ), A tricyclopentanyl group represented by the following formula (3d), a tricyclopentenyl group represented by the following formula (3e), and the like. In addition, when UV polymerization is employed in the synthesis of the (meth) acrylic polymer (B) or in the preparation of the pressure-sensitive adhesive composition, it is difficult to cause polymerization inhibition. Among (meth) acrylic monomers having a ring or higher alicyclic structure, in particular, a dicyclopentanyl group represented by the following formula (3a), an adamantyl group represented by the following formula (3c), and the following formula A (meth) acrylic monomer having a saturated structure such as a tricyclopentanyl group represented by (3d) can be suitably used as a monomer constituting the (meth) acrylic polymer (B).

Examples of (meth) acrylic monomers having a tricyclic or higher alicyclic structure having such a bridged ring structure include dicyclopentanyl methacrylate, dicyclopentanyl acrylate, and dicyclopentanyloxyethyl. Methacrylate, dicyclopentanyloxyethyl acrylate, tricyclopentanyl methacrylate, tricyclopentanyl acrylate, 1-adamantyl methacrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, 2-methyl-2-adamantyl acrylate, (Meth) acrylic acid esters such as 2-ethyl-2-adamantyl methacrylate and 2-ethyl-2-adamantyl acrylate can be mentioned. These (meth) acrylic monomers can be used alone or in combination of two or more.

  Furthermore, in the (meth) acrylic polymer (B), a functional group having reactivity with an epoxy group or an isocyanate group may be introduced. Examples of such a functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and a mercapto group, and a monomer having such a functional group when the (meth) acrylic polymer (B) is produced. Is preferably used (copolymerized).

  The weight average molecular weight of the (meth) acrylic polymer (B) is 1000 or more and less than 30000, preferably 1500 or more and less than 20000, and more preferably 2000 or more and less than 10,000. When the molecular weight is 30000 or more, the effect of improving the adhesive strength of the adhesive tape may not be sufficiently obtained. Moreover, since it becomes low molecular weight as it is less than 1000, the adhesive force of an adhesive tape and the fall of a retention characteristic may be caused.

  The measurement of the weight average molecular weight of the acrylic polymer (A) or the (meth) acrylic polymer (B) can be obtained by polystyrene conversion by the GPC method. Specifically, TSKgelGMH-H (20) × 2 columns are used in HPLC 8020 manufactured by Tosoh Corporation, and the measurement is performed with a tetrahydrofuran solvent at a flow rate of about 0.5 ml / min.

  As described above, the content of the (meth) acrylic polymer (B) is 1 to 70 parts by mass, preferably 2 to 50 parts by mass with respect to 100 parts by mass of the acrylic polymer (A). More preferably, it is 3 to 40 parts by mass. If the (meth) acrylic polymer (B) is added in excess of 70 parts by mass, the elastic modulus of the pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition according to this embodiment is increased, and the adhesiveness at low temperatures is poor. Or may not develop adhesive force even at room temperature. Moreover, when the addition amount of (meth) acrylic-type polymer (B) is less than 1 part, the effect may not be acquired.

  The (meth) acrylic polymer (B) has a glass transition temperature (Tg) of 0 ° C. or higher and 300 ° C. or lower, preferably 20 ° C. or higher and 300 ° C. or lower, more preferably 40 ° C. or higher and 300 ° C. or lower. When the glass transition temperature (Tg) is less than 20 ° C., the cohesive force at room temperature or higher of the pressure-sensitive adhesive layer is lowered, and the holding characteristics and the adhesiveness at high temperature may be lowered. Table 1 shows glass transition temperatures of typical materials that can be used as the (meth) acrylic polymer (B) in the present embodiment. The glass transition temperature shown in Table 1 is a nominal value described in literatures, catalogs, or the like, or a value calculated based on the following formula (4) (Fox formula).

_{1 / Tg = W 1 / Tg} 1 + W 2 / Tg 2 + ··· + Wn / Tg n (4)
[In the formula (4), Tg is the glass transition temperature (unit: K) of the (meth) acrylic polymer (B), and Tg _i (i = 1, 2,... N) is the monomer i is a homopolymer. When formed, the glass transition temperature (unit: K), W _i (i = 1, 2,... N) represents the mass fraction of all monomer components of monomer i. ]
The above formula (4) is a calculation formula when the (meth) acrylic polymer (B) is composed of n types of monomer components of monomer 1, monomer 2,..., Monomer n.

  Abbreviations in Table 1 indicate the following compounds.

DCPMA: dicyclopentanyl methacrylate DCPA: dicyclopentanyl acrylate IBXMA: isobornyl methacrylate IBXA: isobornyl acrylate CHMA: cyclohexyl methacrylate CHA: cyclohexyl acrylate IBMA: isobutyl methacrylate MMA: methyl methacrylate ADMA: 1-adamantyl methacrylate ADA: 1-adamantyl acrylate The preferred embodiments of the (meth) acrylic polymer (B) described above are summarized as follows.

[1] The glass transition temperature of the (meth) acrylic polymer (B) is from 0 ° C. to 300 ° C. [2] The (meth) acrylic polymer (B) is cyclohexyl (meth) acrylate, ( A (meth) acrylic monomer having an alicyclic structure in the side chain such as isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylate is included as a monomer unit.

[3] The alicyclic hydrocarbon group of the (meth) acrylic monomer having an alicyclic structure has a bridged ring structure.

<Method for producing (meth) acrylic polymer (B)>
The (meth) acrylic polymer (B) is obtained by, for example, polymerizing a (meth) acrylic monomer having the above-described structure by a solution polymerization method, a bulk polymerization method, an emulsion polymerization method, a suspension polymerization, a bulk polymerization, or the like. Can be produced.

<Method for adjusting molecular weight of (meth) acrylic polymer (B)>
In order to adjust the molecular weight of the (meth) acrylic polymer (B), a chain transfer agent can be used during the polymerization. Examples of the chain transfer agent used include compounds having a mercapto group such as octyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, mercaptoethanol; thioglycolic acid, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, T-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, thioglycolate of ethylene glycol, thioglycolate of neopentyl glycol, thioglycolate of pentaerythritol A glycolic acid ester is mentioned.

  Although it does not restrict | limit especially as the usage-amount of a chain transfer agent, Usually, 0.1-20 mass parts of chain transfer agents with respect to 100 mass parts of (meth) acrylic-type monomers, Preferably, 0.2-15 masses Part, more preferably 0.3 to 10 parts by mass. Thus, the (meth) acrylic-type polymer (B) of a suitable molecular weight can be obtained by adjusting the addition amount of a chain transfer agent. In addition, a chain transfer agent can be used individually or in combination of 2 or more types.

[Hydrogenated type tackifying resin (C)]
Specifically, the hydrogenation type tackifying resin (C) is made by adding hydrogen to a tackifying resin such as petroleum resin, terpene resin, coumarone / indene resin, styrene resin, rosin resin, alkylphenol resin, xylene resin. It can be selected from added derivatives. For example, the hydrogenated petroleum resin can be selected from aromatic, dicyclopentadiene, aliphatic, and aromatic-dicyclopentadiene copolymer. Further, the hydrogenated terpene resin can be selected from terpene phenol resin, aromatic terpene resin, and the like. Among these, it is particularly preferable to use petroleum resins or terpene resins.

  The softening point of the hydrogenated tackifying resin (C) is preferably from 80 to 200 ° C, more preferably from 100 to 200 ° C. When the softening point of the hydrogenated tackifying resin (C) is within this range, a high cohesive force can be obtained.

  As described above, the content of the hydrogenated tackifying resin (C) is 1 to 50 parts by mass with respect to 100 parts by mass of the acrylic polymer (A), preferably 2 to 40 parts by mass, More preferably, it is 3-30 mass parts. When the addition amount of the hydrogenated tackifying resin (C) is more than 50 parts by mass, the cohesive force may be reduced. Moreover, when the addition amount of hydrogenation-type tackifying resin (C) is less than 1 part, the adhesive force improvement effect may not be acquired.

  The blending amount of the (meth) acrylic polymer (B) (oligomer) and the hydrogenated tackifying resin (C) is (meth) acrylic polymer (B) / hydrogenated tackifying resin (C) = 1. /0.12 to 1.7, preferably 1 / 0.15 to 1.6, and more preferably 1 / 0.2 to 1.55 (both mass ratios). It is preferable that the blending amount of both is within the range because the adhesion reliability is improved. This is presumably because the (meth) acrylic polymer (B) acts as a compatibilizing agent for the hydrogenated tackifying resin, and both are uniformly dispersed to improve adhesion reliability.

  The acrylic pressure-sensitive adhesive composition according to this embodiment contains the above-mentioned acrylic polymer (A), (meth) acrylic polymer (B), and hydrogenated tackifying resin (C) as essential components, Various additives common in the field of pressure-sensitive adhesive compositions can be contained as optional components. Examples of such optional components include plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), antioxidants, leveling agents, stabilizers, preservatives, and the like. Conventionally known additives can be used as such additives.

  Acrylic polymer (A) as an adhesive composition, (meth) acrylic polymer (B) having a weight average molecular weight of 1000 or more and less than 30000 as a tackifying resin, and hydrogenated tackifying resin (C) As for the acrylic adhesive layer containing these, the solvent insoluble component rate is 40-90 mass%, Preferably it is desirable that it is 45-85 mass%. When the solvent-insoluble component ratio is less than 40% by mass, the cohesive force may be insufficient and the retention characteristics may not be satisfied. When the solvent-insoluble component rate exceeds 90% by mass, the cohesive force becomes too high, May be inferior to repulsion resistance test. In addition, the evaluation method of a solvent insoluble component rate is mentioned later.

  Then, the structure of the acrylic adhesive tape (or acrylic adhesive sheet) which has an adhesive layer containing the acrylic adhesive composition which has the above-mentioned composition is demonstrated.

  The acrylic pressure-sensitive adhesive tape according to this embodiment includes a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive composition. The acrylic pressure-sensitive adhesive tape is a so-called pressure-sensitive adhesive with a base material provided with the pressure-sensitive adhesive layer fixed on one or both sides of the sheet-like base material (support), that is, without intending to separate the pressure-sensitive adhesive layer from the base material. The pressure-sensitive adhesive layer may be a tape, or the pressure-sensitive adhesive layer is provided on a substrate having releasability such as a release liner (release paper, a resin sheet subjected to a release treatment on the surface), and a pressure-sensitive adhesive layer at the time of application. It may be a so-called substrate-less pressure-sensitive adhesive tape in which the substrate that supports the substrate is removed. The concept of the pressure-sensitive adhesive tape here may include what are called pressure-sensitive adhesive sheets, pressure-sensitive adhesive labels, pressure-sensitive adhesive films, and the like. The pressure-sensitive adhesive layer is not limited to those formed continuously, and may be a pressure-sensitive adhesive layer formed in a regular or random pattern such as a dot shape or a stripe shape.

As the base material, for example,
Plastic films such as polypropylene film, ethylene-propylene copolymer film, polyester film, polyvinyl chloride film;
Foam substrates such as polyurethane foam and polyethylene foam;
Kraft paper, crepe paper, Japanese paper, etc .;
Cotton, soft cloth, etc .;
Nonwoven fabrics such as polyester nonwoven fabrics and vinylon nonwoven fabrics;
Metal foil such as aluminum foil and copper foil;
Can be appropriately selected and used depending on the application of the adhesive tape. As the plastic film, any of an unstretched film and a stretched (uniaxially stretched or biaxially stretched) film can be used. Further, the surface of the substrate on which the pressure-sensitive adhesive layer is provided may be subjected to surface treatment such as application of a primer and corona discharge treatment. The thickness of the substrate can be appropriately selected according to the purpose, but is generally about 10 μm to 500 μm (typically 10 μm to 200 μm).

  The pressure-sensitive adhesive layer can be a cured layer of an acrylic pressure-sensitive adhesive composition. That is, the pressure-sensitive adhesive layer can be formed by applying (for example, applying) an acrylic pressure-sensitive adhesive composition to a suitable base material and then appropriately performing a curing treatment. When performing 2 or more types of hardening processes (drying, bridge | crosslinking, superposition | polymerization, etc.), these can be performed simultaneously or in multiple steps. In a pressure-sensitive adhesive composition using a partial polymer (acrylic polymer syrup), typically, as the curing treatment, a final copolymerization reaction is performed (the partial polymer is subjected to a further copolymerization reaction). A complete polymer is formed). For example, if it is a photocurable adhesive composition, light irradiation is implemented. If necessary, curing treatment such as cross-linking and drying may be performed. For example, when it is necessary to dry with a photocurable adhesive composition, it is good to perform photocuring after drying. In the pressure-sensitive adhesive composition using a completely polymerized product, typically, as the curing treatment, treatments such as drying (heat drying) and crosslinking are performed as necessary.

  The acrylic pressure-sensitive adhesive composition can be applied, for example, using a conventional coater such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater or the like. . In the case of a pressure-sensitive adhesive tape with a base material, the pressure-sensitive adhesive composition may be directly applied to the base material to form a pressure-sensitive adhesive layer, or the pressure-sensitive adhesive layer formed on the release liner may be transferred to the base material. .

  The thickness of the pressure-sensitive adhesive layer is not particularly limited, but usually good adhesiveness can be realized by setting the thickness to, for example, 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more. For example, it is appropriate to set the thickness of the pressure-sensitive adhesive layer to about 10 to 250 μm.

  The acrylic adhesive tape according to the present embodiment includes, for example, PE (polyethylene), PP (polypropylene), ABS (acrylonitrile-butadiene-styrene copolymer), SBS (styrene-butadiene-styrene block copolymer), PC ( Polycarbonate), PVC (vinyl chloride), PMMA (polymethyl methacrylate resin) and other resins including acrylic resins, and members made of metals such as SUS and aluminum It can be suitably used for applications where it is bonded (fixed) to the surface of building materials, home appliances and the like.

  Moreover, the acrylic adhesive tape which concerns on this embodiment is used suitably for the use which bonds various optical members, for example to a liquid crystal cell, an optical polyester film, a touch panel member, etc. Therefore, the technique shown here includes a laminate in which an adhesive layer containing an acrylic adhesive composition is provided on an optical member. This laminate typically has a form in which the pressure-sensitive adhesive layer on the optical member is protected by a release liner. The optical member provided with such an adhesive layer can be easily attached to, for example, the surface of a plastic cover lens panel, glass, liquid crystal cell, or the like. The optical member is not particularly limited, and may be a polarizing film, a retardation film, a transparent conductive film (ITO film), or the like. Such an optical member may have a single layer structure made of the same material or a multilayer structure made of a plurality of materials. As a method of forming the pressure-sensitive adhesive layer on the optical member, a method of directly applying or a method of transferring can be appropriately employed as in the case of forming the pressure-sensitive adhesive layer on the substrate. Typically, the pressure-sensitive adhesive layer formed on the release liner is transferred to the base surface of the optical member.

  As described above, the acrylic pressure-sensitive adhesive composition according to the present embodiment includes the acrylic polymer (A) as the pressure-sensitive adhesive composition, and only the hydrogenated tackifying resin (C) as the tackifying resin. In addition, when the pressure-sensitive adhesive layer is formed using the acrylic pressure-sensitive adhesive composition by including the (meth) acrylic polymer (B), the adhesion of the acrylic pressure-sensitive adhesive tape to the low-polarity adherend Can be improved. As a result, the adhesion reliability of acrylic adhesive tapes to various adherends with different surface polarities, including low-polar adherends, can be improved, and acrylic adhesive tapes can be used in the fields of automobiles, household appliances, etc. It can be used for various joining applications.

  The reason why the adhesiveness of the acrylic pressure-sensitive adhesive tape to the low-polar adherend is improved is that the (meth) acrylic polymer (B) is compatible with the hydrogenated tackifying resin (C) and the acrylic polymer ( This is presumed to be compatible with A). That is, it is presumed that the (meth) acrylic polymer (B) acts as a compatibilizing agent for the hydrogenated tackifying resin (C), and as a result of the uniform dispersion of both, the adhesion reliability is improved.

  In particular, when the (meth) acrylic polymer (B) has an alicyclic structure, the alicyclic structure increases compatibility with the hydrogenated tackifier resin (C), while (meth) acrylic. It is presumed that the main chain of the polymer (B) is compatible with the acrylic polymer.

  Moreover, the acrylic pressure-sensitive adhesive composition according to this embodiment can be designed so as not to contain an acidic group in the monomer constituting the acrylic polymer (A). In this case, it is possible to obtain an acrylic pressure-sensitive adhesive tape that is less affected by metal corrosion caused by acidic groups. In addition, even if it is a case where the monomer which comprises an acrylic polymer (A) contains an acidic group, the change in the adhesive characteristic of an acrylic adhesive tape can be aimed at.

  EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

  Table 2 shows components of the acrylic pressure-sensitive adhesive compositions according to Examples 1 to 11 and Comparative Examples 1 to 8.

Abbreviations in Table 2 indicate the following compounds.
2EHA: 2-ethylhexyl acrylate NVP: N-vinyl-2-pyrrolidone HEAA: N-hydroxyethyl acrylamide AA: acrylic acid DCPMA: dicyclopentanyl methacrylate DCPMA (low): lower polymerization degree than DCPMA (Example 8) Dicyclopentanyl methacrylate CHMA: Cyclohexyl methacrylate IBMA: Isobutyl methacrylate TMPTA: Trimethylolpropane triacrylate HDDA: 1,6-hexanediol diacrylate

(Measurement of solvent insoluble component ratio)
The solvent-insoluble component ratio is obtained by sampling 0.1 g of the pressure-sensitive adhesive composition and precisely weighing (mass before immersion), and immersing it in 50 ml of ethyl acetate at room temperature (20 to 25 ° C.) for 1 week. The solvent (ethyl acetate) insoluble matter was taken out, and the solvent insoluble matter was dried at 130 ° C. for 2 hours and then weighed (mass after soaking and drying) to calculate the solvent insoluble component rate calculation formula “solvent insoluble component rate (mass%). ) = [(Mass after soaking / drying) / (mass before soaking)] × 100 ”.

(Preparation of acrylic polymer syrup 1 (2EHA / NVP = 86/14) as component (A))
86 parts by mass of 2-ethylhexyl acrylate (2EHA), 14 parts by mass of N-vinyl-2-pyrrolidone (NVP), 0.05 parts by mass of a photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF), and photopolymerization start 0.05 parts by mass of an agent (trade name: Irgacure 651, manufactured by BASF) was charged into a four-necked flask. The mixture was exposed to ultraviolet light under a nitrogen atmosphere and partially photopolymerized to obtain a partially polymerized product (acrylic polymer syrup 1) having a polymerization rate of about 11% by mass.

(Preparation of acrylic polymer syrup 2 (2EHA / AA = 94/6) as component (A))
94 parts by mass of 2-ethylhexyl acrylate (2EHA), 6 parts by mass of acrylic acid (AA), 0.05 parts by mass of a photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF), and a photopolymerization initiator (trade name: 0.05 part by mass (Irgacure 651, manufactured by BASF) was charged into a four-necked flask. The mixture was exposed to ultraviolet light under a nitrogen atmosphere and partially photopolymerized to obtain a partially polymerized product (acrylic polymer syrup 2) having a polymerization rate of about 8% by mass.

(Preparation of acrylic polymer syrup 3 (2EHA / NVP / HEAA = 86/13/1) as component (A))
86 parts by mass of 2-ethylhexyl acrylate (2EHA), 13 parts by mass of N-vinyl-2-pyrrolidone (NVP), 1 part by mass of N-hydroxyethylacrylamide (HEAA), photopolymerization initiator (trade name: Irgacure 184, BASF Corporation) 0.05 parts by mass) and 0.05 part by mass of a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) were charged into a four-necked flask. The mixture was exposed to ultraviolet light under a nitrogen atmosphere and partially photopolymerized to obtain a partially polymerized product (acrylic polymer syrup 3) having a polymerization rate of about 10% by mass.

(Preparation of (meth) acrylic polymer 1 (CHMA / IBMA = 60/40) as component (B))
After compounding cyclohexyl methacrylate (CHMA, 60 parts by mass), isobutyl methacrylate (IBMA, 40 parts by mass) and thioglycolic acid (4.0 parts by mass), nitrogen gas was blown to remove dissolved oxygen. Next, when the temperature was raised to 90 ° C., perhexyl O (manufactured by NOF Corporation, 0.005 parts by mass) and perhexyl D (manufactured by NOF Corporation, 0.01 parts by mass) were mixed. Furthermore, after stirring at 90 ° C. for 1 hour, the temperature was raised to 150 ° C. over 1 hour and stirred at 150 ° C. for 1 hour. Subsequently, it heated up to 170 degreeC over 1 hour, and stirred for 60 minutes at 170 degreeC.

  Next, the pressure was reduced at 170 ° C., and the mixture was stirred for 1 hour to remove residual monomers, whereby (meth) acrylic polymer 1 was obtained. The obtained (meth) acrylic polymer 1 had a glass transition temperature (calculated from the Fox equation) of 59 ° C. and a weight average molecular weight of 4000.

(Preparation of (meth) acrylic polymer 2 (DCPMA) as component (B))
100 parts by mass of toluene, 100 parts by mass of dicyclopentanyl methacrylate (DCPMA) (trade name: FA-513M, manufactured by Hitachi Chemical Co., Ltd.), and 4 parts by mass of thioglycolic acid (GSH acid) as a chain transfer agent Charged to a neck flask. Then, after stirring at 70 ° C. for 1 hour in a nitrogen atmosphere, 0.2 part by mass of azobisisobutyronitrile as a thermal polymerization initiator is added and reacted for 2 hours at 70 ° C., followed by 2 at 80 ° C. Reacted for hours. Thereafter, the reaction solution was put in a temperature atmosphere of 130 ° C., and toluene, the chain transfer agent, and the unreacted monomer were removed by drying to obtain a solid (meth) acrylic polymer 2. The obtained (meth) acrylic polymer 2 had a glass transition temperature of 175 ° C. and a weight average molecular weight of 4,600.

(Preparation of (meth) acrylic polymer 3 (DCPMA (low)) as component (B))
100 parts by mass of toluene, 100 parts by mass of dicyclopentanyl methacrylate (DCPMA) (trade name: FA-513M, manufactured by Hitachi Chemical Co., Ltd.), and 4 parts by mass of thioglycolic acid (GSH acid) as a chain transfer agent Charged to a neck flask. Then, after stirring for 1 hour at 75 ° C. in a nitrogen atmosphere, 0.2 part by mass of azobisisobutyronitrile as a thermal polymerization initiator was added and reacted for 2 hours at 75 ° C., followed by 2 at 80 ° C. Reacted for hours. Thereafter, the reaction solution was added to a temperature atmosphere of 130 ° C., and toluene, the chain transfer agent, and the unreacted monomer were removed by drying to obtain a solid (meth) acrylic polymer 3. The obtained (meth) acrylic polymer 3 had a glass transition temperature of 175 ° C. and a weight average molecular weight of 3000.

Example 1
(Preparation of acrylic pressure-sensitive adhesive composition)
100 parts by mass of the acrylic polymer syrup 1 described above, 8 parts by mass of the (meth) acrylic polymer 1 described above, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) After adding 12 parts by mass and 0.12 parts by mass of trimethylolpropane triacrylate, they were uniformly mixed to prepare an acrylic pressure-sensitive adhesive composition.
(Preparation of adhesive layer sheet)
The acrylic pressure-sensitive adhesive composition described above was applied to the release-treated surface of a 38 μm thick polyester film (trade name: MRF, manufactured by Mitsubishi Plastics Co., Ltd.) whose one surface was peeled with silicone so that the final thickness was 50 μm. Thus, a coating layer was formed. Next, on the surface of the applied acrylic pressure-sensitive adhesive composition, a 38 μm thick polyester film (trade name: MRN, manufactured by Mitsubishi Resin Co., Ltd.), one side of which was peeled with silicone, was applied to the peeled surface of the film. Covered side by side. Thereby, the application layer (adhesive layer) of the acrylic adhesive composition was shielded from oxygen. The pressure-sensitive adhesive layer sheet thus obtained was irradiated with ultraviolet rays having an illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a maximum sensitivity of about 350 nm) using a black light lamp (manufactured by Toshiba Corporation) for 360 seconds. Irradiated. The solvent-insoluble component ratio of the pressure-sensitive adhesive layer made of the acrylic pressure-sensitive adhesive composition thus obtained was 69.8% by mass. The polyester film coated on both sides of the pressure-sensitive adhesive layer functions as a release liner.

(Example 2)
In 100 parts by mass of the acrylic polymer syrup 1 described above, 15 parts by mass of the above-mentioned (meth) acrylic polymer 1 and Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 15 parts by weight and 0.18 parts by weight of trimethylolpropane triacrylate were added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 67.7% by mass.

(Example 3)
20 parts by mass of the above-mentioned (meth) acrylic polymer 1 and 100% by mass of the acrylic polymer syrup 1 described above, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 5 parts by weight and 0.2 parts by weight of trimethylolpropane triacrylate were added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 71.3% by mass.

Example 4
12 parts by mass of the above-mentioned (meth) acrylic polymer 1 and 100% by mass of the acrylic polymer syrup 1 described above, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1, except that 8 parts by weight and 0.15 parts by weight of trimethylolpropane triacrylate were added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 71.9% by mass.

(Example 5)
12 parts by mass of the above-mentioned (meth) acrylic polymer 1 and 100% by mass of the acrylic polymer syrup 1 described above, Alcon P100 (hydrogenated petroleum resin, softening point 100 ° C., manufactured by Arakawa Chemical Industries, Ltd.) An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1, except that 8 parts by weight and 0.15 parts by weight of trimethylolpropane triacrylate were added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 71.1% by mass.

(Example 6)
12 parts by mass of the above-described (meth) acrylic polymer 1 and 100 parts by mass of the acrylic polymer syrup 3 described above, Clearon P135 (hydrogenated terpene resin, softening point 135 ° C., manufactured by Yasuhara Chemical Co., Ltd.) 8 masses An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 0.15 parts by weight of trimethylolpropane triacrylate was added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 61.1% by mass.

(Example 7)
To 100 parts by mass of the above-mentioned acrylic polymer syrup 3, 12 parts by mass of the (meth) acrylic polymer 1 described above, Imabe P125 (hydrogenated petroleum resin (dicyclopentadiene / aromatic copolymer)), softening Acrylic pressure-sensitive adhesive composition and pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 8 parts by mass of point 125 ° C, manufactured by Idemitsu Kosan Co., Ltd. and 0.12 parts by mass of trimethylolpropane triacrylate were added. Obtained. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 75.0% by mass.

(Example 8)
To 100 parts by mass of the acrylic polymer syrup 1 described above, 12 parts by mass of the (meth) acrylic polymer 2 described above, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C.,
Arakawa Chemical Industries, Ltd.) An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 8 parts by weight and 0.1 part by weight of trimethylolpropane triacrylate were added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 63.4% by mass.

Example 9
100 parts by mass of the acrylic polymer syrup 2 described above, 12 parts by mass of the (meth) acrylic polymer 1 described above, Imabe P125 (hydrogenated petroleum resin (dicyclopentadiene / aromatic copolymer)), softening Acrylic pressure-sensitive adhesive composition and pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 8 parts by mass of point 125 ° C, manufactured by Idemitsu Kosan Co., Ltd. and 0.11 parts by mass of trimethylolpropane triacrylate were added. Obtained. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 62.5% by mass.

(Example 10)
100 parts by mass of the acrylic polymer syrup 2 described above, 12 parts by mass of the (meth) acrylic polymer 3 described above, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 8 parts by mass and 0.14 parts by mass of trimethylolpropane triacrylate were added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 65.7% by mass.

(Example 11)
12 parts by mass of the above-mentioned (meth) acrylic polymer 1 and 100% by mass of the above-mentioned acrylic polymer syrup 2, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 8 parts by mass and 0.12 parts by mass of trimethylolpropane triacrylate were added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 61.3% by mass.

(Comparative Example 1)
Acrylic pressure-sensitive adhesive composition and pressure-sensitive adhesive layer in the same manner as in Example 1 except that 0.045 parts by mass of 1,6-hexanediol diacrylate was added to 100 parts by mass of the acrylic polymer syrup 1 described above. A sheet was obtained. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 77.4% by mass.

(Comparative Example 2)
Acrylic pressure-sensitive adhesive composition and pressure-sensitive adhesive layer in the same manner as in Example 1 except that 0.07 part by mass of 1,6-hexanediol diacrylate was added to 100 parts by mass of the acrylic polymer syrup 2 described above. A sheet was obtained. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 75.2% by mass.

(Comparative Example 3)
The same as Example 1 except that 20 parts by mass of the above-mentioned (meth) acrylic polymer 1 and 0.12 parts by mass of trimethylolpropane triacrylate were added to 100 parts by mass of the above-mentioned acrylic polymer syrup 1. Thus, an acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 73.4% by mass.

(Comparative Example 4)
The same procedure as in Example 1 was conducted except that 20 parts by mass of the above-mentioned (meth) acrylic polymer 1 and 0.14 parts by mass of trimethylolpropane triacrylate were added to 100 parts by mass of the above-mentioned acrylic polymer syrup 2. Thus, an acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 67.3% by mass.

(Comparative Example 5)
To 100 parts by mass of the acrylic polymer syrup 1 described above, 8 parts by mass of Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., Arakawa Chemical Industries, Ltd.) and 0.08 parts by mass of trimethylolpropane triacrylate Except having added, it carried out similarly to Example 1, and obtained the acrylic adhesive composition and the adhesive layer sheet. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 75.0% by mass.

(Comparative Example 6)
To 100 parts by mass of the acrylic polymer syrup 1 described above, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) 20 parts by mass, 0.12 parts by mass of trimethylolpropane triacrylate Except having added, it carried out similarly to Example 1, and obtained the acrylic adhesive composition and the adhesive layer sheet. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 71.7% by mass.

(Comparative Example 7)
To 100 parts by mass of the acrylic polymer syrup 2 described above, Alcon P125 (hydrogenated petroleum resin, softening point 125 ° C., manufactured by Arakawa Chemical Industries, Ltd.) 20 parts by mass, trimethylolpropane triacrylate 0.15 parts by mass Except having added, it carried out similarly to Example 1, and obtained the acrylic adhesive composition and the adhesive layer sheet. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 67.3% by mass.

(Comparative Example 8)
To 100 parts by mass of the acrylic polymer syrup 1 described above, 12 parts by mass of the (meth) acrylic polymer 1 described above, Mighty Ace K-125 (terpene phenol resin, softening point 125 ° C., manufactured by Yasuhara Chemical Co., Ltd.) 8 An acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive layer sheet were obtained in the same manner as in Example 1 except that 0.25 part by weight of trimethylolpropane triacrylate was added. The solvent-insoluble component ratio of the obtained pressure-sensitive adhesive layer was 74.7% by mass.

(Test method)
[180 ° peel adhesion test]
One release liner (polyester film) of the pressure-sensitive adhesive layer sheet according to each example and each comparative example was peeled off, a polyethylene terephthalate film having a thickness of 50 μm was bonded, and the test piece was cut to a width of 25 mm. . In addition, a 2 mm thick polypropylene plate (Part No. 1600, manufactured by Takiron Co., Ltd.) and an acrylic plate (Acrylite, manufactured by Mitsubishi Rayon Co., Ltd.) cleaned with isopropyl alcohol were prepared. Then, the other release liner (polyester film) of the pressure-sensitive adhesive layer sheet was peeled off, and a 2 kg roller was reciprocated to attach the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer sheet to the polypropylene plate and the acrylic plate.
After sticking the pressure-sensitive adhesive layer sheet to the polypropylene plate and the acrylic plate, it was left for 30 minutes in an environment of 23 ° C. (initial stage). Moreover, after sticking an adhesive layer sheet | seat on a polypropylene board and an acrylic board, after making it pass for 48 hours in a 40 degreeC environment, it was left to stand in a 23 degreeC environment for 30 minutes (normal state). And about each adhesive layer sheet of an initial condition and a normal condition, the other end of an adhesive layer sheet is peeled in the peeling direction of 180 degree | times at the speed | rate of 300 mm / min, and the adhesive force (resistance force) at that time ) (Unit: N / 25 mm). In each of the polypropylene plate and the acrylic plate, in both the initial condition and the normal condition, the case where the adhesive strength was 16 N / 25 mm or more was judged as good (◯), and the case where it was less than 16 N / 25 mm was judged as bad (x). Table 3 shows the measurement results.

[Repulsion resistance test]
The pressure-sensitive adhesive layer sheets according to each Example and each Comparative Example were cut to a width of 10 mm and a length of 90 mm, and bonded to a clean aluminum plate having a thickness of 0.5 mm, a width of 10 mm, and a length of 90 mm. A test piece was obtained. Next, the test piece was curved so that the curvature would be R50 mm by placing the aluminum plate side of the test piece along the cylinder. Then, the other release liner (polyester film) of the pressure-sensitive adhesive layer sheet was peeled off and laminated to the above-described polypropylene plate and acrylic plate. With the test piece laminated to the polypropylene plate and the acrylic plate, the adhesive layer sheet floated after passing for 1 hour at room temperature (25 ° C.), that is, from the surface of the polypropylene plate and the acrylic plate to the pressure-sensitive adhesive layer. The distance (average of heights at both ends) (unit: mm) was measured. The case where the floated distance was 10 mm or less was judged as good (◯), and the case where the floated distance exceeded 10 mm was judged as defective (x). Table 3 shows the measurement results. In addition, the numerical value shown in Table 3 is an average value about arbitrary plural points.

[Retention characteristics test]
One release liner (polyester film) of the pressure-sensitive adhesive layer sheet according to each example and each comparative example was peeled off, a polyethylene terephthalate film having a thickness of 50 μm was bonded, and the test piece was cut into a width of 10 mm. . The adhesive surface of the test piece was bonded to a bakelite plate cleaned with toluene in an area of 10 mm in width and 20 mm in length, and left in an environment at 60 ° C. for 30 minutes. Thereafter, a weight was hung at one end of the test piece so that a load of 500 g was applied in the shear direction, and the weight was left suspended in an environment of 60 ° C. for 1 hour to evaluate the holding characteristics. The case where the test piece did not fall was evaluated as good (◯), and the case where it dropped was regarded as defective (x). Table 3 shows the measurement results.

  As shown in Table 3, Comparative Examples 1 to 4 and 7 had poor adhesion to the polypropylene plate in both the initial condition and the normal condition. Moreover, although the adhesive force with respect to the polypropylene plates of Comparative Examples 5, 6, and 8 was good under normal conditions, it was poor under initial conditions. Further, in Comparative Examples 1 and 7, the adhesive strength to the acrylic plate was poor in both the initial condition and the normal condition. Moreover, although the adhesive force with respect to the acrylic board of Comparative Examples 6 and 8 was favorable under normal conditions, it was poor under initial conditions. On the other hand, Examples 1 to 11 had good adhesive strength in both the initial condition and the normal condition in both the polypropylene plate and the acrylic plate. That is, it was confirmed that the adhesiveness to the low-polar adherend was improved in all Examples as compared with Comparative Examples 1-8.

  In Comparative Example 6, the repulsion resistance was poor in both the polypropylene plate and the acrylic plate. Further, Comparative Examples 1, 2, 5, and 7 were poor in repulsion resistance in the polypropylene plate. On the other hand, in all the examples, the repulsion resistance was good in both the polypropylene plate and the acrylic plate.

  Moreover, in all Examples and Comparative Examples, good holding characteristics (cohesive force) were observed. Therefore, it was confirmed that Examples 1-11 had the outstanding adhesive force, the outstanding repulsion resistance, and the outstanding retention characteristic.

  Summarizing the above results, both (meth) acrylic polymer (B) and hydrogenated tackifying resin (C) are used as the tackifying resin to be added to the acrylic polymer (A) as the adhesive composition. It has been confirmed that by including the above, it is possible to obtain an unprecedented effect that the adhesive force, the repulsion resistance, and the holding characteristics with respect to the adherend including the low polar adherend can be improved.

Claims (10)

100 parts by mass of an acrylic polymer (A),
1 to 70 parts by weight of a (meth) acrylic polymer (B) having a weight average molecular weight of 1000 or more and less than 30000,
1 to 50 parts by mass of hydrogenated tackifying resin (C);
An acrylic pressure-sensitive adhesive composition comprising:   The acrylic pressure-sensitive adhesive composition according to claim 1, wherein the glass transition temperature of the (meth) acrylic polymer (B) is 0 ° C or higher and 300 ° C or lower.   The acrylic pressure-sensitive adhesive composition according to claim 1 or 2, wherein the (meth) acrylic polymer (B) contains a (meth) acrylic monomer having an alicyclic structure in the side chain as a monomer unit.   The acrylic pressure-sensitive adhesive composition according to claim 3, wherein the alicyclic hydrocarbon group of the (meth) acrylic monomer having an alicyclic structure has a bridged ring structure.   The acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the hydrogenated tackifying resin (C) is a petroleum-based resin or a terpene-based resin.   The acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein a softening point of the hydrogenated tackifying resin (C) is 80 to 200 ° C. The acrylic polymer (A) has at least one monomer selected from the group consisting of N-vinyl cyclic amide represented by acrylic (1) described in the following general formula and a carboxyl group-containing monomer as a monomer unit. The acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 6, which is contained.

In the general formula (1), R ³ is a divalent organic group.   The acrylic adhesive layer which consists of an acrylic adhesive composition of any one of Claims 1 thru | or 7.   The acrylic pressure-sensitive adhesive layer according to claim 8, comprising 40 to 90% by mass of a solvent-insoluble component.   The acrylic adhesive tape containing the acrylic adhesive layer of Claim 8 or 9.