JP6317938B2 - Adhesive sheet - Google Patents

Description

  The present invention relates to an adhesive sheet.

  The pressure-sensitive adhesive sheet is widely used in industry as a simple and reliable means for fixing various members. An adhesive sheet is produced using the adhesive which shows viscoelasticity at normal temperature, and various members are fixed by crimping | bonding the adhesive surface to a to-be-adhered body. In recent years, pressure-sensitive adhesive sheets that are excellent in flexibility and weather resistance and have strong adhesive strength have been developed, and such pressure-sensitive adhesive sheets are used for fixing home appliances, interior / exterior parts of automobiles, and building materials. As such an adhesive sheet, for example, those described in the following documents are known.

Special table 2012-519750 gazette

  As the uses of the pressure-sensitive adhesive sheet are diversified, a pressure-sensitive adhesive sheet capable of exhibiting high adhesive force on a wide range of adherends is required. For example, pressure-sensitive adhesive sheets that exhibit high adhesive strength are demanded not only for highly polar adherends such as metals but also for low-polar adherends such as resins. However, the actual situation is that such an adhesive sheet has not yet been provided.

  An object of the present invention is to solve the conventional problems and to solve the following objects. That is, an object of this invention is to provide the adhesive sheet which has high adhesive force with respect to the various to-be-adhered bodies from which polarity differs.

  As a result of intensive studies to achieve the above object, the present inventor, as a result, contains an acrylic polymer (a) as a base polymer and constitutes an adhesive surface (A) and the adhesive layer (A). And a structural unit derived from any one or more acidic group-containing monomers selected from the group consisting of a hydroxyl group-containing monomer and a carboxyl group-containing monomer. And a structural unit derived from at least one basic group-containing monomer selected from the group consisting of a heterocyclic ring-containing vinyl monomer and an amide group-containing monomer, and the thickness of the viscoelastic layer (B) is The pressure-sensitive adhesive sheet having a thickness of 200 μm or more was found to have a high adhesive force on a wide range of adherends having different polarities, and the present invention was completed.

  In the pressure-sensitive adhesive sheet, the acrylic polymer (a) contains 50% by mass or more of a structural unit derived from a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms. But you can.

  In the pressure-sensitive adhesive sheet, the acrylic polymer (a) preferably contains 2% by mass or more of a structural unit derived from a hydroxyl group-containing monomer and 10% by mass or more of a structural unit derived from a heterocyclic ring-containing vinyl monomer. .

  In the pressure-sensitive adhesive sheet, the acrylic polymer (a) may include a structural unit derived from a polyfunctional monomer having two or more polymerizable functional groups.

  In the pressure-sensitive adhesive sheet, the acrylic polymer (a) may include 0.1% by mass or more of a structural unit derived from a carboxyl group-containing monomer.

  In the pressure-sensitive adhesive sheet, the viscoelastic layer (B) may include hollow particles.

  In the pressure-sensitive adhesive sheet, the viscoelastic body layer (B) may include bubbles.

  In the pressure-sensitive adhesive sheet, the viscoelastic body layer (B) may include an acrylic polymer (b) as a base polymer.

  In the pressure-sensitive adhesive sheet, the acrylic polymer (b) contains 50% by mass or more of a structural unit derived from a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms. And 5 mass% or more of the structural unit derived from a carboxyl group-containing monomer may be included.

  The pressure-sensitive adhesive sheet may include the pressure-sensitive adhesive layer (A) on both the front and back surfaces of the viscoelastic layer (B).

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive sheet which has high adhesive force can be provided with respect to the wide to-be-adhered body from which polarity differs.

1 is a schematic cross-sectional view of an adhesive sheet according to an embodiment.

  The pressure-sensitive adhesive sheet according to this embodiment comprises a pressure-sensitive adhesive layer (A) that constitutes a pressure-sensitive adhesive surface and a viscoelastic body layer (B) that supports the pressure-sensitive adhesive layer (A).

  In general, the term “adhesive sheet” may be referred to by a name different from “adhesive tape”, “adhesive film”, and the like, but in this specification, the expression is unified as “adhesive sheet”. Moreover, in this specification, the surface which touches a to-be-adhered body in an adhesive sheet is called "adhesion surface."

[Adhesive layer (A)]
The pressure-sensitive adhesive layer (A) is designed so as to be able to form a pressure-sensitive adhesive surface that exhibits high adhesive strength to adherends of various polarities, from adherends with high polarity to adherends with low polarity. It is an adhesive layer.

  In the present specification, the “adherent having a high polarity” or the “adherent having a low polarity” specifically refers to an “adherent having a high surface energy” or “an adherend having a low surface energy”. means. The surface energy of each adherend is a value inherent to the composition and chemical composition of the material, and is an important physical property value that affects the “wetability” of the adherend. ing. In general, it is known that those having a large surface energy value (large polarity) have good adhesion, and those having a small value (small polarity) have poor adhesion.

  The surface energy can be obtained by measuring a contact angle of a droplet on each adherend surface. As a surface energy of a typical material, for example, the following values can be used as a guide.

Stainless steel (SUS): 700 to 1100 × 10 ⁻³ N / m, polycarbonate (PC): 42 × 10 ⁻³ N / m, acrylonitrile butadiene styrene (ABS): 42 × 10 ⁻³ N / m, polystyrene (PSt ): 36 × 10 ⁻³ N / m.

In the present specification, an adherend made of a material such as SUS having a surface energy of 200 × 10 ⁻³ N / m or more is referred to as “adhesive with high polarity”, and the surface energy is 100 × 10 ⁻³ N / m. An adherend made of materials such as PC, ABS, and PSt that are less than or equal to m is handled as an “adhesive with low polarity”.

  Specifically, the pressure-sensitive adhesive layer (A) is based on an acrylic polymer (a), and the acrylic polymer (a) is selected from the group consisting of a hydroxyl group-containing monomer and a carboxyl group-containing monomer. Derived from any one or more basic group-containing monomers selected from the group consisting of structural units derived from any one or more acidic group-containing monomers, and heterocyclic-containing vinyl monomers and amide group-containing monomers. Containing structural units.

  The content (% by mass) of the acrylic polymer (a) in the pressure-sensitive adhesive layer (A) (100% by mass) is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 75% by mass or more. . The upper limit of the content (mass%) is not particularly limited, but is preferably 99.9% by mass or less, more preferably 99.8% by mass or less, and still more preferably 99.5% by mass or less.

(Acrylic polymer (a))
The acrylic polymer (a) (100% by mass) is a structural unit derived from any one or more acidic group-containing monomers selected from the group consisting of a hydroxyl group-containing monomer and a carboxyl group-containing monomer, and a heterocyclic ring-containing vinyl system And a structural unit derived from any one or more basic group-containing monomers selected from the group consisting of monomers and amide group-containing monomers.

(Acid group-containing monomer)
As the acidic group-containing monomer, one or more kinds selected from the group consisting of a hydroxyl group-containing monomer and a carboxyl group-containing monomer as described below can be used. The following can be used individually by 1 type or in combination of 2 or more types. As the acidic group-containing monomer, a hydroxyl group-containing monomer is preferably included, and it is more preferable to use one or more selected monomers for the hydroxyl group-containing monomer and the carboxyl group-containing monomer.

  The structural unit derived from the acidic group-containing monomer is preferably contained in an amount of 2% by mass or more, more preferably 4% by mass or more, relative to the acrylic polymer (a) (100% by mass). . Moreover, the structural unit derived from the acidic group-containing monomer is preferably contained in an amount of 15% by mass or less, more preferably 10% by mass or less, relative to the acrylic polymer (a) (100% by mass).

(Hydroxyl group-containing monomer)
The structural unit derived from the hydroxyl group-containing monomer may be contained in an amount of preferably 3% by mass or more with respect to the acrylic polymer (a) (100% by mass). Moreover, the structural unit derived from the hydroxyl group-containing monomer is preferably contained in an amount of 5% by mass or less, more preferably 4% by mass or less, with respect to the acrylic polymer (a) (100% by mass).

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and vinyl alcohol. And allyl alcohol. These may be used alone or in combination of two or more. Among these, 2-hydroxyethyl acrylate (HEA) is preferable.

  In this specification, “(meth) acryl” represents “acryl” and / or “methacryl” (any one or both of “acryl” and “methacryl”).

(Carboxyl group-containing monomer)
The structural unit derived from the carboxyl group-containing monomer is preferably contained in an amount of 0.1 mass or more, more preferably 0.5 mass% or more (for example, 1 mass) with respect to the acrylic polymer (a) (100 mass%). % Or more) may be included. Further, the structural unit derived from the carboxyl group-containing monomer is preferably contained in an amount of 10% by mass or less, more preferably 9% by mass or less, and still more preferably, based on the acrylic polymer (a) (100% by mass). 8 mass% or less may be contained.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and acid anhydrides thereof (for example, acid anhydrides such as maleic anhydride and itaconic anhydride). Containing monomer) and the like. These may be used alone or in combination of two or more. Among these, acrylic acid (AA) is preferable.

  When the acidic group-containing monomer is used in combination with one or more selected from a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a hydroxyl group-containing monomer, the structural unit derived from each monomer is an acrylic polymer (a) ( 100% by mass) is preferably contained in an amount of 0.5% by mass, more preferably 1% by mass or more. For example, when 2-hydroxyethyl acrylate and acrylic acid are used in combination, it is preferable that both of them are 1% by mass or more. More preferably, for example, 2-hydroxyethyl acrylate and acrylic acid can be 3 mass% or more and 1 mass% or more, respectively.

(Basic group-containing monomer)
As a basic group containing monomer, 1 or more types can be selected from the group which consists of a heterocyclic containing monomer and an amide group containing monomer as follows. The basic group-containing monomer preferably includes a heterocyclic ring-containing monomer.

  The structural unit derived from the basic group-containing monomer is preferably contained in an amount of 10% by mass or more, more preferably 15% by mass or more, relative to the acrylic polymer (a) (100% by mass). preferable. The structural unit derived from the basic group-containing monomer is preferably contained in an amount of 40% by mass or less, more preferably 30% by mass or less, based on the acrylic polymer (a) (100% by mass). .

(Heterocycle-containing vinyl monomer)
The structural unit derived from the heterocyclic ring-containing vinyl monomer is preferably contained in an amount of 12% by mass or more, more preferably 15% by mass or more, based on the acrylic polymer (a) (100% by mass). The structural unit derived from the heterocyclic ring-containing vinyl monomer is preferably contained in an amount of 30% by mass or less, more preferably 25% by mass or less, and more preferably 25% by mass or less, based on the acrylic polymer (a) (100% by mass). Preferably, it may be contained in an amount of 20% by mass or less.

  Examples of the heterocyclic ring-containing vinyl monomer include N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, and N-vinylimidazole. These may be used alone or in combination of two or more. Among these, N-vinyl-2-pyrrolidone (NVP) is preferable.

(Amide group-containing monomer)
The structural unit derived from the amide group-containing monomer is preferably contained in an amount of 0.1% by mass or more, more preferably 0.5% by mass or more, relative to the acrylic polymer (a) (100% by mass). Good. The structural unit derived from the amide group-containing vinyl monomer is preferably contained in an amount of 30% by mass or less, more preferably 25% by mass or less, and more preferably 25% by mass or less, based on the acrylic polymer (a) (100% by mass). Preferably, it may be contained in an amount of 20% by mass or less.

  Examples of the amide group-containing monomer include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide. N-hydroxyethyl (meth) acrylamide and the like. These may be used alone or in combination of two or more.

  In addition, it is preferable that acrylic polymer (a) contains 2 mass% or more of structural units derived from a hydroxyl group-containing monomer, and contains 10 mass% or more of structural units derived from a heterocyclic ring-containing vinyl monomer. . If the pressure-sensitive adhesive layer (A) includes the acrylic polymer (a) having such a configuration, it is possible to obtain a pressure-sensitive adhesive surface exhibiting high adhesive strength on a wide range of adherends having different polarities. It becomes easy.

((Meth) acrylic acid alkyl ester)
The acrylic polymer (a) may be referred to as a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms (simply referred to as “(meth) acrylic acid alkyl ester”). 50% by mass or more is preferable.

  The structural unit derived from the (meth) acrylic acid alkyl ester is more preferably contained in an amount of 60% by mass or more, more preferably 70% by mass or more, relative to the acrylic polymer (a) (100% by mass). Good. Moreover, the structural unit derived from the (meth) acrylic acid alkyl ester is preferably contained in an amount of 85% by mass or less, more preferably 80% by mass or less, with respect to the acrylic polymer (a) (100% by mass). Also good.

  Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, ( Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, (meth) acrylic acid Heptyl, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic Isodecyl acid, undecyl (meth) acrylate, dodecyl (meth) acrylate (Meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, (meth) acrylic acid pentadecyl, (meth) acrylic acid hexadecyl, (meth) acrylic acid heptadecyl, (meth) acrylic acid octadecyl, (meth) acrylic acid nonadecyl, ( Examples include (meth) eicosyl acrylate. These may be used alone or in combination of two or more.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms, and an alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms. Esters are more preferable, and n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), and the like are still more preferable.

(Multifunctional monomer)
The acrylic polymer (a) may include a structural unit derived from a polyfunctional monomer having two or more polymerizable functional groups containing an unsaturated double bond (sometimes referred to as a polyfunctional monomer). When the structural unit derived from a polyfunctional monomer is contained in the acrylic polymer (a), the acrylic polymer (a) contains a crosslinked acrylic polymer, and the pressure-sensitive adhesive layer (A ) Is improved in cohesiveness and adhesive strength.

  The structural unit derived from the polyfunctional monomer is preferably contained in an amount of 0.01% by mass or more, more preferably 0.02% by mass or more, and still more preferably 0% with respect to the acrylic polymer (100% by mass). .05 mass% or more may be contained. Moreover, the structural unit derived from the polyfunctional monomer is preferably contained in an amount of 0.5% by mass or less, more preferably 0.3% by mass or less, with respect to the acrylic polymer (100% by mass). .

  Examples of the multifunctional monomer include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, and neopentyl glycol. Di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl (Meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate and the like. These may be used alone or in combination of two or more. The polyfunctional monomer is preferably a polyfunctional (meth) acrylate such as 1,6-hexanediol diacrylate (HDDA).

(Other monomers)
The acrylic polymer (a) may contain a monomer other than the above-described monomer as a structural unit as long as the object of the present invention is not impaired. Examples of such monomers include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, Amide group-containing monomers such as N-hydroxyethyl (meth) acrylamide; Amino group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; Epoxy group-containing monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; 2-hydroxyethylacrylo Phosphoric acid group-containing monomers such as sulfate; Imido group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide; Isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate; Vinyl esters such as vinyl acetate and vinyl propionate; Styrene, Aromatic vinyl compounds such as vinyl toluene; olefins or dienes such as ethylene, butadiene, isoprene and isobutylene; vinyl ethers such as vinyl alkyl ether; vinyl chloride and the like. These may be used alone or in combination of two or more.

(Polymerization method of acrylic polymer (a))
The acrylic polymer (a) can be prepared by using a known or conventional polymerization method. Examples of the polymerization method include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a photopolymerization method. Among these, when preparing the acrylic polymer (a), it is preferable to use a curing reaction by heat or active energy rays (for example, ultraviolet rays) using a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator. In particular, it is preferable to use a curing reaction using a photopolymerization initiator because it has advantages such as shortening the polymerization time. These polymerization methods can be used singly or in appropriate combination of two or more.

  In the polymerization of the acrylic polymer (a), a known or conventional polymerization initiator can be used depending on the polymerization method, the polymerization mode, and the like. Moreover, you may mix | blend the other component included in an adhesive layer (A) with a polymerization initiator at the time of preparation of an acrylic polymer (a). In addition, you may use polymerization initiators, such as a thermal-polymerization initiator and a photoinitiator, which are utilized for preparation of an acrylic polymer (a) individually or in combination of 2 or more types.

  Examples of the thermal polymerization initiator include 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'-dimethyleneisobutylamidine) dihydrochloride, 2, , 2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate and other azo polymerization initiators; Peroxide polymerization initiators such as benzoyl peroxide, t-butyl permaleate, lauroyl peroxide; for example, persulfates such as potassium persulfate and ammonium persulfate; for example, benzoyl peroxide, t-butyl hydroperoxide Peroxide initiators such as hydrogen peroxide; for example, substituted ethane initiators such as phenyl-substituted ethane; for example, combinations of persulfate and sodium bisulfite, combinations of peroxide and sodium ascorbate, etc. And redox polymerization initiators. 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. The thermal polymerization can be preferably performed at a temperature of, for example, about 20 to 100 ° C. (typically 40 to 80 ° C.).

  Examples of the photopolymerization initiator include benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, and photoactive oxime photopolymerization initiator. Initiators, benzoin photopolymerization initiators, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanthone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, and the like It is done.

  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 [ BASF, trade name: Irgacure 651], anisole methyl ether, and the like. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone [manufactured by BASF, trade name: Irgacure 184], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one [manufactured by BASF, trade name: Irgacure 2959], 2-hydroxy-2-methyl-1-phenyl-propane Examples include -1-one [manufactured by BASF, trade name: Darocur 1173], methoxyacetophenone, and the like. 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 photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl. 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.

  Examples of the acylphosphine oxide 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-methoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2-methoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methyl Propan-1-yl) phosphine oxide, bis (2,4-dimethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxy Phenyl) phosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine Sid, 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-dimethoxybenzoyl Benzyloctylphosphine 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-trimethyl Benzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide, 2,6-dimethoxyoxybenzoyl-2 , 4,6-Trimethylbenzoyl-n-butylbutyl Fin oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2, 4,6-trimethylbenzoyl) phosphine oxide] decane, tri (2-methylbenzoyl) phosphine oxide and the like.

  The initiator used for the polymerization of the acrylic polymer (a) is not particularly limited, but it is preferable to use a photopolymerization initiator from the advantage that the polymerization time can be shortened. For example, the acrylic polymer (a) can be generated by irradiating the monomer composition containing the photopolymerization initiator with active energy rays (for example, ultraviolet rays) to polymerize the monomer.

  The amount (lower limit) of the photopolymerization initiator is not particularly limited as long as the acrylic polymer (a) can be formed by a photopolymerization reaction. For example, it is used to form the acrylic polymer (a). The amount is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and still more preferably 0.05 parts by mass or more with respect to 100 parts by mass of all the monomer components. Moreover, it is preferable that the usage-amount (upper limit) of a photoinitiator is similarly 5 mass parts or less, More preferably, it is 3 mass parts or less, More preferably, it is 2 mass parts or less. If it is the said range, a polymerization reaction can fully be performed and the fall of the molecular weight of the polymer to produce | generate can be suppressed. As a result, the cohesive force of the pressure-sensitive adhesive layer (A) to be formed is ensured.

  In activating the photopolymerization initiator, it is important to irradiate the monomer composition containing the photopolymerization initiator with active energy rays. Examples of such active energy rays include ionizing radiation such as α rays, β rays, γ rays, neutron rays, electron rays, and ultraviolet rays, and ultraviolet rays are particularly preferable. The irradiation energy, irradiation time, irradiation method, and the like of the active energy ray are not particularly limited as long as the photopolymerization initiator can be activated to cause the monomer component to react.

(Other ingredients)
The pressure-sensitive adhesive layer (A) may contain a filler as a component other than the acrylic polymer (a). The filler may be appropriately blended in the pressure-sensitive adhesive layer (A) as necessary in order to improve various performances such as reinforcement, workability, handleability, and adhesion.

  The filler is not particularly limited. For example, metals such as copper, nickel, aluminum, chromium, iron, and stainless steel; metal oxides such as alumina and zirconia; carbides such as silicon carbide, boron carbide, and nitrogen carbide Nitrides such as aluminum nitride, silicon nitride, boron nitride; inorganic materials such as calcium carbide, calcium carbonate, aluminum hydroxide, glass, silica; polystyrene, acrylic resin (eg, polymethyl methacrylate), phenol resin, benzoguanamine resin, urea Examples thereof include polymers such as resins, silicone resins, nylon, polyester, polyurethane, polyethylene, polypropylene, polyamide, polyimide, silicone, and vinylidene chloride. Alternatively, natural raw material particles such as volcanic shirasu and sand may be used. These may be used alone or in combination of two or more.

  The outer shape and shape of the filler are not particularly limited. The outer shape of the filler may be, for example, a spherical shape, a flake shape, or an indefinite shape. The structure of the filler can be, for example, a dense structure, a porous structure, a hollow structure, or the like. As the filler, it is preferable to use hollow particles.

  Examples of the hollow particles include inorganic hollow particles and organic hollow particles. Specific examples of the inorganic hollow particles include glass hollow balloons such as hollow glass balloons, metal compound hollow balloons such as hollow alumina balloons, and porcelain hollow balloons such as hollow ceramic balloons. Specific examples of organic hollow particles include resin hollow balloons such as hollow acrylic balloons and hollow vinylidene chloride balloons. The hollow particles may be used alone or in combination of two or more.

  Among the hollow particles, inorganic hollow particles are preferable, and hollow glass balloons are particularly preferable from the viewpoints of polymerization efficiency by active energy rays (particularly, ultraviolet rays) and weight. If a hollow glass balloon is used as the hollow particles, the adhesive performance of the pressure-sensitive adhesive layer can be improved without impairing other properties such as shearing force and holding force. Examples of commercially available hollow glass balloons include, for example, trade names “Glass Micro Balloon”, “Fuji Balloon H-40”, “Fuji Balloon H-35” manufactured by Fuji Silysia Chemical Ltd., and trade names manufactured by Tokai Kogyo Co., Ltd. “Cell Star Z-20”, “Cell Star Z-27”, “Cell Star CZ-31T”, “Cell Star Z-36”, “Cell Star Z-39”, “Cell Star Z-39”, “Cell Star T-36”, “ Cell Star PZ-6000 ”, trade name“ Syracx Fine Balloon ”manufactured by Fine Balloon, trade names“ Q-CEL ™ 5020 ”,“ Q-CEL ™ 7014 ”manufactured by Potters Ballottini, Product names “Sphericel ™ 110P8”, “Sphericel ™ 25P45”, “Sphericel ( Trademark) 34P30 "," Sphericel (TM) 60P18 ", trade names" Super Balloon BA-15 "and" Super Balloon 732C "manufactured by Showa Chemical Industry Co., Ltd. can be used. The surface of the hollow particles may be subjected to various surface treatments (for example, low surface tension treatment with a silicone compound or a fluorine compound).

The average particle diameter (lower limit) of the filler is not particularly limited, but is preferably 0.1 μm. The average particle diameter (upper limit) is preferably 500 μm or less, more preferably 200 μm or less, and still more preferably 80 μm or less. The specific gravity (true density) (lower limit) of the filler is not particularly limited, but is preferably 0.1 g / cm ³ or more, and more preferably 0.15 g / cm ³ . The specific gravity (upper limit) is preferably 5.0 g / cm ³ or less, more preferably 3.0 g / cm ³ . If the specific gravity of the filler (especially hollow particles) is in such a range, it is incorporated into the composition for forming the pressure-sensitive adhesive layer (A) (hereinafter referred to as “pressure-sensitive adhesive layer-forming composition”). It is preferable that lifting during the process is suppressed and the composition is easily dispersed uniformly in the pressure-sensitive adhesive layer forming composition.

  Moreover, the usage-amount (upper limit value) of the hollow particle mix | blended in an adhesive layer (A) is suitably 20 mass% or less of the whole adhesive layer (A), for example, and is 10 mass% or less. It is preferable that Moreover, the same usage-amount (lower limit) can be 1 mass% or more, for example.

  The pressure-sensitive adhesive layer (A) may contain a colorant (pigment, dye, etc.) as long as the object of the present invention is not impaired. The colorant can be blended into the pressure-sensitive adhesive layer (A) as necessary in order to impart optical properties (for example, light-shielding properties) and design properties.

  The colorant is not particularly limited. For example, when the pressure-sensitive adhesive layer (A) is formed by curing the pressure-sensitive adhesive layer-forming composition by a photopolymerization method, in order to color the pressure-sensitive adhesive layer (A). A pigment (colored pigment) that does not exclude photopolymerization can be used as a colorant. In the case where light-shielding property is imparted to the pressure-sensitive adhesive layer (A), carbon black (for example, acetylene black, ketjen black, furnace black, channel black, thermal black) that is a black pigment can be used.

  The use amount (upper limit) of the colorant is, for example, suitably 10% by mass or less of the entire pressure-sensitive adhesive layer (A) in consideration of the degree of coloration, photopolymerization reactivity, etc., and 5% by mass. The following is preferable. Moreover, the same usage-amount (lower limit) can be 0.1 mass% or more, for example.

  In addition, the pressure-sensitive adhesive layer (A) is a thermally expandable microsphere, a tackifier, a crosslinking agent (for example, an epoxy-based crosslinking agent, an isocyanate-based crosslinking agent, a silicone-based crosslinking agent, an oxazoline) unless the purpose of the present invention is impaired. Crosslinking agent, aziridine crosslinking agent, silane crosslinking agent, alkyl etherified melamine crosslinking agent, metal chelate crosslinking agent), crosslinking accelerator, silane coupling agent, anti-aging agent, pigment, dye, UV absorber, Antioxidants, chain transfer agents, plasticizers, softeners, antistatic agents, solvents, polymers, adhesives (eg rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamides) System adhesives, urethane adhesives, fluorine adhesives, epoxy adhesives) and the like. These may be used alone or in combination of two or more.

  The pressure-sensitive adhesive layer (A) preferably has a structure that does not substantially contain bubbles. In the present specification, “substantially does not contain bubbles” means that the bubbles are not actively formed in the pressure-sensitive adhesive layer (A) except when inevitably mixed. The bubble content in the pressure-sensitive adhesive layer (A) is ideally zero. The bubble content in the actual pressure-sensitive adhesive layer (A) is preferably 3% by volume or less, more preferably 1% by volume, based on the total volume (100% by volume) of the pressure-sensitive adhesive layer (A). It is as follows.

(Method for forming pressure-sensitive adhesive layer (A))
The pressure-sensitive adhesive layer (A) used in the pressure-sensitive adhesive sheet of the present embodiment is formed using, for example, a pressure-sensitive adhesive layer forming composition. The composition for forming an adhesive layer is not particularly limited as long as it can form the above-described adhesive layer (A) of the present invention, and can be appropriately selected depending on the purpose. As the pressure-sensitive adhesive layer forming composition, from the viewpoint of workability and the like, a monomer composition composed of each monomer component used for forming the acrylic polymer (a) and the monomer component are polymerized. It is preferable to use a curable adhesive layer forming composition containing a mixture of a polymerization initiator and other components added as necessary. In particular, the pressure-sensitive adhesive layer forming composition is preferably a photocurable pressure-sensitive adhesive layer forming composition using a photopolymerization initiator as the polymerization initiator. The curable pressure-sensitive adhesive layer forming composition is a so-called solventless pressure-sensitive adhesive layer forming composition, and is prepared by mixing the polymerization initiator and the like with the monomer composition. .

  In addition, the said monomer composition consists of a mixture of monomer components, such as a (meth) acrylic-acid alkylester, a hydroxyl-containing monomer, a heterocyclic ring-containing vinyl monomer, for example. Although the said monomer composition changes with the kind of monomer component, a composition ratio, etc., normally it has comprised the liquid state. Therefore, in order to increase the viscosity of the monomer composition and improve workability (handleability), etc., the monomer component contained in the monomer composition is partially polymerized in advance. A polymer may be formed. Thereby, typically, a syrup-like syrup-like (viscous liquid) composition in which a polymer formed from a part of monomer components and unreacted monomers are mixed can be obtained (hereinafter referred to as such). The partially polymerized product may be referred to as “syrup composition” or simply “syrup”. The curable composition for forming a pressure-sensitive adhesive layer is prepared by adding the other components to the syrup composition as necessary. The unreacted monomer component contained in the syrup composition is appropriately polymerized when the curable pressure-sensitive adhesive layer forming composition is cured.

  For forming the syrup composition, a known or conventional polymerization method can be used. For example, the monomer components in the monomer composition may be appropriately polymerized using various polymerization initiators (for example, photopolymerization initiators) exemplified in the item of the acrylic polymer (a). In addition, the polymerization rate of the partial polymer in the syrup composition is adjusted to, for example, 5 to 15% by mass, preferably 7 to 10% by mass. As for the polymerization rate of the partial polymer, for example, the correlation between the viscosity of the syrup composition and the polymerization rate of the partial polymer is grasped in advance, and the viscosity of the syrup composition is determined based on the correlation. It can adjust suitably by adjusting. The partial polymer is finally contained in the pressure-sensitive adhesive layer (A) as a part of the acrylic polymer (a).

  When a polyfunctional monomer is used as the monomer component used to form the acrylic polymer (a), the polyfunctional monomer is blended in the monomer composition before the partial polymer is formed. Alternatively, it may be blended into the syrup-like composition after the partial polymer is formed. However, from the viewpoint of forming the cross-linked acrylic polymer (a) and reliably increasing the cohesiveness of the pressure-sensitive adhesive layer (A), the polyfunctional monomer is the above-mentioned after the partial polymer is formed. It is preferable to mix | blend with a syrup-like composition.

  The curable pressure-sensitive adhesive layer-forming composition is applied in a layered manner on a suitable support such as a release liner or a substrate described later after preparation. Thereafter, a curing step is performed on the layered pressure-sensitive adhesive layer forming composition. Moreover, a drying process is given before and after a hardening process as needed. When the composition for forming an adhesive layer contains a thermal polymerization initiator as a polymerization initiator, the composition for forming an adhesive layer is cured by starting a polymerization reaction by heating. On the other hand, when the pressure-sensitive adhesive layer forming composition contains a photopolymerization initiator as a polymerization initiator, the pressure-sensitive adhesive layer forming composition undergoes a polymerization reaction by irradiation with active energy rays such as ultraviolet rays. It is initiated and cured (photocured). The active energy ray may be irradiated from one side of the layered pressure-sensitive adhesive layer-forming composition or from both sides. Thus, when the said adhesive layer formation composition is hardened | cured, the adhesive layer sheet provided with the adhesive layer (A) which can be utilized for the adhesive sheet of this embodiment is obtained.

  It should be noted that a known or conventional oxygen blocking method (for example, a layered pressure-sensitive adhesive layer-forming composition (adhesive) is used so that the polymerization reaction is not inhibited by oxygen in the air when curing with active energy rays (photocuring). An appropriate support such as a release liner or a base material may be bonded onto the agent layer (A)), or a photocuring reaction may be performed in a nitrogen atmosphere).

  For the application (coating) of the pressure-sensitive adhesive layer forming composition, a known or conventional coating method can be used, and a general coater (for example, a gravure roll coater, a reverse roll coater, a kiss roll). A coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, direct coater, etc.).

  The pressure-sensitive adhesive layer (A) is a composition for forming a pressure-sensitive adhesive layer other than the above-described composition for forming a pressure-sensitive adhesive layer (for example, solvent-type pressure-sensitive adhesive layer formation), unless the object of the present invention is impaired. For example, an emulsion-type pressure-sensitive adhesive layer-forming composition).

(Thickness of adhesive layer (A))
In general, the thickness (upper limit) of the pressure-sensitive adhesive layer (A) in the pressure-sensitive adhesive sheet of the present embodiment is preferably 300 μm or less. Since the pressure-sensitive adhesive sheet of the present invention includes the viscoelastic body layer (B), even if the pressure-sensitive adhesive layer (A) has a thickness of 300 μm or less, it effectively absorbs unevenness and steps on the adherend surface. It is possible to adhere well to the adherend surface, and high peel strength can be realized. From this viewpoint, the thickness of the pressure-sensitive adhesive layer (A) is preferably 300 μm or less, more preferably 250 μm or less, and still more preferably 220 μm or less. Moreover, the thickness (lower limit) of the pressure-sensitive adhesive layer (A) is not particularly limited, and can be, for example, 1 μm or more. From the viewpoint of peel strength and the like, the thickness of the pressure-sensitive adhesive layer (A) is suitably 10 μm or more. In the present invention, the thickness of the pressure-sensitive adhesive layer (A) can be 50 μm or more, and may be 90 μm or more (for example, more than 100 μm).

[Viscoelastic layer (B)]
The viscoelastic body layer (B) has a thickness of 200 μm or more and is a layer designed to support the pressure-sensitive adhesive layer (A) from the back surface of the pressure-sensitive adhesive surface. The viscoelastic layer (B) may be an adhesive layer or a non-adhesive layer. Although it does not specifically limit, In the adhesive sheet of this embodiment, it is preferable that a viscoelastic body layer (B) is an adhesive layer.

  Here, the “adhesive layer” is a SUS304 stainless steel plate as an adherend in accordance with JIS Z0237 (2004), and a 2 kg roller is reciprocated once in a measurement environment at 23 ° C. to be bonded to the adherend. It means a layer having a peel strength of 0.1 N / 20 mm or more when peeled in the 180 ° direction under the condition of a tensile speed of 300 mm / min 30 minutes later. On the other hand, the “non-adhesive layer” refers to a layer not corresponding to the adhesive layer, and typically refers to a layer having a peel strength of less than 0.1 N / 20 mm. The layer that does not stick to the stainless steel plate when the 2 kg roller is reciprocated once in a measurement environment of 23 ° C. and pressed against the SUS304 stainless steel plate is a non-adhesive layer here. This is a typical example included in the concept.

The viscoelastic body layer (B) is not particularly limited as long as it exhibits the properties of a viscoelastic body in a temperature range near room temperature. Here, the “viscoelastic body” means a material having both properties of viscosity and elasticity, that is, a material having a property that satisfies the phase of the complex elastic modulus exceeding 0 and less than π / 2 (typically 25 ° C. The material having the above-mentioned properties. From the viewpoint of flexibility and the like, a material having a property satisfying the complex tensile modulus E ^* (1 Hz) <10 ⁷ dyne / cm ² (typically a material having the above property at 25 ° C.) is preferable.

  The viscoelastic body layer (B) is an acrylic viscoelastic body, rubber viscoelastic body, silicone viscoelastic body, polyester viscoelastic body, urethane viscoelastic body, polyether viscoelastic body, polyamide viscoelastic body. The layer comprised including 1 type (s) or 2 or more types selected from various viscoelastic bodies, such as a body and a fluorine-type viscoelastic body, may be sufficient. Here, the acrylic viscoelastic body refers to a viscoelastic body having an acrylic polymer as a base polymer. This also applies to rubber-based and other viscoelastic bodies.

  The viscoelastic layer (B) preferably has high shear strength, and hollow particles and other fillers can be added as necessary. The viscoelastic body layer (B) is preferably an acrylic viscoelastic body containing an acrylic polymer (b) as a base polymer. Hereinafter, the acrylic polymer (b) constituting the viscoelastic body layer (B) and other components will be described.

(Acrylic polymer (b))
The content (% by mass) of the acrylic polymer (b) in the viscoelastic layer (B) (100% by mass) is preferably 50% by mass or more, more preferably 60% by mass or more, and further more preferably 70% by mass or more. preferable. The upper limit of the content (% by mass) is not particularly limited, but is preferably 98% by mass or less, and more preferably 90% by mass or less. When the content (mass%) is within such a range, it is easy to adjust the balance between flexibility and cohesion in the viscoelastic layer (B).

((Meth) acrylic acid alkyl ester)
As an acrylic polymer (b), what contains the structural unit derived from the (meth) acrylic-acid alkylester which has a C1-C20 linear or branched alkyl group, for example is preferable.

  As a (meth) acrylic-acid alkylester, the thing similar to the (meth) acrylic-acid alkylester utilized for formation of an adhesive layer (A) can be used, for example. Also in the acrylic polymer (b), the (meth) acrylic acid alkyl ester may be used alone or in combination of two or more.

  The (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 14 carbon atoms from the viewpoint of storage elastic modulus of the pressure-sensitive adhesive, and n- Butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA) are more preferable.

  The proportion (lower limit) of the structural unit derived from the (meth) acrylic acid alkyl ester contained in the acrylic polymer (b) is not particularly limited, but is preferably 60% by mass or more, More preferably, it is 70 mass% or more, More preferably, it is 80 mass% or more. The ratio (upper limit) is preferably 98% by mass or less, more preferably 95% by mass or less, from the viewpoint of the cohesiveness of the viscoelastic body layer (B).

(Carboxyl group-containing monomer)
The acrylic polymer (b) preferably contains a structural unit derived from a carboxyl group-containing monomer. As a carboxyl group-containing monomer, the thing similar to the carboxyl group-containing monomer utilized for formation of an adhesive layer (A) can be used, for example. Also in the acrylic polymer (b), the carboxyl group-containing monomers may be used alone or in combination of two or more. In addition, as a carboxyl group-containing monomer, acrylic acid (AA) is preferable.

  The proportion (lower limit) of the mass of the structural unit derived from the carboxyl group-containing monomer contained in the acrylic polymer (b) is preferably 5% by mass or more, more preferably 7% by mass or more, and still more preferably. Is 10% by mass or more. Moreover, it is preferable that it is 40 mass% or less, and, as for the same ratio (upper limit), it is more preferable that it is 30 mass% or less.

(Multifunctional monomer)
The acrylic polymer (b) may contain a polyfunctional monomer. As a polyfunctional monomer, the thing similar to the polyfunctional monomer utilized for formation of an adhesive layer (A) can be used, for example. Also in the acrylic polymer (b), the polyfunctional monomer may be used alone or in combination of two or more.

  The polyfunctional monomer is preferably a polyfunctional (meth) acrylate such as 1,6-hexanediol diacrylate (HDDA) or dipentaerythritol hexaacrylate (DPHA) from the viewpoint of reactivity or the like.

  When using a polyfunctional monomer, it is preferable that the ratio (lower limit) of the structural unit derived from a polyfunctional monomer contained in an acrylic polymer (b) is 0.01 mass% or more. Moreover, it is preferable that it is 2 mass% or less from the viewpoint of the softness | flexibility of a viscoelastic body layer (B), More preferably, the ratio (upper limit) is 1 mass% or less.

(Other monomer components)
The acrylic polymer (b) may contain a structural unit derived from a monomer other than the above-mentioned monomers for the purpose of adjusting the glass transition temperature (Tg) and improving the cohesive force.

  Examples of such monomers include hydroxyl group-containing monomers, amide group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, aziridine group-containing monomers, amino group-containing monomers, keto group-containing monomers, isocyanate group-containing monomers, Alkoxy group-containing monomers, alkoxysilyl group-containing monomers, functional group-containing monomers such as macromonomers having a radical polymerizable vinyl group at the terminal of a monomer obtained by polymerizing vinyl groups, carboxylic acid vinyl esters, aromatic vinyl compounds, aromatic rings Examples include (meth) acrylates, monomers having a nitrogen atom-containing ring, olefinic monomers, chlorine-containing monomers, and vinyl ether monomers. These may be used alone or in combination of two or more.

  The proportion of the structural units derived from these monomers contained in the acrylic polymer (b) may be appropriately selected depending on the purpose and application, and is not particularly limited, but is 10% by mass or less. It is preferable.

(Monomer composition of acrylic polymer (b))
The monomer composition of the acrylic polymer (b) is preferably adjusted so that the Tg of the acrylic polymer (b) is, for example, −70 ° C. or higher and −10 ° C. or lower. The Tg of the acrylic polymer (b) is suitably −20 ° C. or lower, preferably −30 ° C. or lower, more preferably −40 ° C. or lower, and further preferably −50 ° C. or lower from the viewpoint of flexibility. Moreover, from the viewpoint of cohesiveness, it is usually preferable that the Tg is −65 ° C. or higher.

  In the present specification, the Tg of the acrylic polymer (b) refers to the Tg of the homopolymer (homopolymer) of each monomer constituting the acrylic polymer (b) and the mass fraction of the monomer (coefficient based on mass). The value obtained from the Fox equation based on the polymerization ratio. Therefore, the Tg of the acrylic polymer (b) can be adjusted by appropriately changing the monomer composition (that is, the type and amount ratio of the monomer used in the synthesis of the acrylic polymer (b)). As the Tg of the homopolymer, a value described in known materials can be adopted.

(Polymerization method of acrylic polymer (b))
The acrylic polymer (b) can be prepared by a known or commonly used polymerization method, similarly to the acrylic polymer (a). For example, a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a photopolymerization method and the like can be used alone or in combination of two or more, but an active energy ray using a photopolymerization initiator (for example, ultraviolet rays) It is particularly preferred to use the curing reaction by In the polymerization of the acrylic polymer (b), the same initiators as those that can be used for the polymerization of the acrylic polymer (a) can be used.

(Other ingredients)
The viscoelastic layer (B) preferably contains a filler. By including a filler in the viscoelastic layer (B), the shear strength of the viscoelastic layer (B) can be increased. Thereby, the resistance (peeling strength) with respect to peeling an adhesive sheet from a to-be-adhered body can improve. Moreover, by using a filler, the excessive deformation | transformation of a viscoelastic body layer (B) can be suppressed, and the balance with the softness | flexibility and cohesion property as the whole adhesive sheet can be adjusted suitably.

  The filler that can be added to the viscoelastic layer (B) is not particularly limited. For example, the same fillers as those exemplified as the filler that can be added to the pressure-sensitive adhesive layer (A) can be used. Among these, it is preferable to use hollow particles. From the viewpoint of photocurability (polymerization reactivity) of the pressure-sensitive adhesive layer forming composition, hollow particles made of an inorganic material can be preferably used. Among such hollow particles, glass balloons such as hollow glass balloons are particularly preferable. For example, trade names “Glass Micro Balloon”, “Fuji Balloon H-40”, “Fuji Balloon H-” manufactured by Fuji Silysia Chemical Ltd. 35 ”, trade names“ Q-CEL ™ 5020 ”,“ Q-CEL ™ 7014 ”, trade names“ Sphericel ™ 110P8 ”,“ Sphericel ™ 25P45 ”manufactured by Potters Barottini, Commercially available products similar to those exemplified as fillers that can be added to the pressure-sensitive adhesive layer (A), such as “Sphericel ™ 34P30” and “Sphericel ™ 60P18” can be used.

  The average particle diameter of the hollow particles used for the pressure-sensitive adhesive layer (B) is not particularly limited. For example, it can be selected from the range of 1 μm to 500 μm, preferably 5 μm to 400 μm, more preferably 10 μm to 300 μm, and still more preferably 10 μm to 200 μm (for example, 10 to 150 μm). The average particle diameter of the hollow particles is usually suitably 50% or less of the thickness of the viscoelastic layer (B), preferably 30% or less (for example, 10% or less).

The specific gravity of the hollow particles is not particularly limited, but for example, 0.1 to 1.8 g / cm ³ , preferably 0.1 to 1.5 g / cm ³ , more preferably in consideration of uniform dispersibility and mechanical strength. Can be selected from a range of 0.1 to 0.5 g / cm ³ (for example, 0.2 to 0.5 g / cm ³ ).

  The usage-amount of the hollow particle used for a viscoelastic body layer (B) is not specifically limited, For example, the whole viscoelastic body layer (B) can be about 1-70 mass%, Usually, 5-50 mass% It is appropriate that the amount is approximately 10 to 40% by mass.

  The viscoelastic body layer (B) may have bubbles. By including bubbles in the viscoelastic body layer (B), the cushioning property of the pressure-sensitive adhesive sheet can be improved and the flexibility can be increased. When the flexibility of the pressure-sensitive adhesive sheet increases, the pressure-sensitive adhesive sheet can easily absorb irregularities and steps on the surface of the adherend, so that the pressure-sensitive adhesive surface can be better adhered to the surface of the adherend. Good adhesion of the pressure-sensitive adhesive surface to the adherend surface can advantageously contribute to an improvement in peel strength for low-polar surfaces and other various surfaces. Moreover, the improvement of the softness | flexibility of an adhesive sheet can also contribute to reduction of the repulsive force of an adhesive sheet. As a result, when the adhesive sheet is attached along the surface of the adherend having a curved surface or a step, or when the adherend to which the adhesive sheet is attached is deformed, the adhesive sheet is caused by its own repulsive force. The phenomenon of peeling (raising) from the surface of the adherend can be effectively suppressed.

  The viscoelastic layer (B) may include both the filler (for example, hollow particles) and bubbles as described above. The pressure-sensitive adhesive sheet containing such a viscoelastic layer (B) is preferable because it tends to have an excellent balance between flexibility and cohesive force.

  The bubbles contained in the viscoelastic layer (B) may be closed cells, open cells, or a mixture of these. From the viewpoint of cushioning properties, the viscoelastic body layer (B) having a structure containing a lot of closed cells is more preferable. In the case of closed cells, gas components contained in the bubbles (gas components that form bubbles, which may be referred to as “bubble-forming gas” hereinafter) are not particularly limited, and are inert gases such as nitrogen, carbon dioxide, and argon. In addition, various gas components such as air may be used. As the bubble forming gas, when a polymerization reaction or the like is performed in a state where the bubble forming gas is included, it is preferable to use a gas that does not inhibit the reaction. From such viewpoints and cost viewpoints, nitrogen can be suitably employed as the bubble forming gas.

  The shape of the bubble is typically approximately spherical, but is not limited thereto. The average diameter of the bubbles (average bubble diameter) is not particularly limited, and can be selected from the range of, for example, 1 μm to 1000 μm, preferably 10 μm to 500 μm, and more preferably 30 μm to 300 μm. The average bubble diameter is usually suitably 50% or less of the thickness of the viscoelastic layer (B), preferably 30% or less (for example, 10% or less).

  When the viscoelastic layer (B) has bubbles, the volume ratio (bubble content rate) of the bubbles in the viscoelastic layer (B) is not particularly limited, and the intended cushioning and flexibility are realized. Can be set as appropriate. For example, it can be about 3 to 70% by volume with respect to the volume of the viscoelastic layer (B) (refers to the apparent volume and can be calculated from the thickness and area of the viscoelastic layer (B)). Usually, about 5 to 50% by volume is appropriate, and about 8 to 40% by volume is preferable.

  In this embodiment, the method for forming the viscoelastic body layer (B) having bubbles (bubble-containing viscoelastic body layer) is not particularly limited, and a known method can be appropriately employed. For example, when preparing a composition for forming the viscoelastic body layer (B) (hereinafter referred to as “composition for forming a viscoelastic body layer”) to form the viscoelastic body layer (B), (1) Viscoelastic body layer-forming composition (preferably a composition of a type that forms a viscoelastic body by curing with an active energy ray such as ultraviolet rays) in which a bubble-forming gas is mixed in advance is contained in bubbles. A method of forming a viscoelastic body layer, (2) a method of forming a bubble-containing viscoelastic body layer by forming bubbles from the foaming agent using a viscoelastic body layer forming composition containing a foaming agent, and the like. It can be adopted as appropriate. The foaming agent to be used is not particularly limited, and can be appropriately selected from known foaming agents. For example, a foaming agent such as a thermally expandable microsphere can be preferably used.

  In the formation of the bubble-containing viscoelastic material layer by the method (1), the method for preparing the viscoelastic material layer forming composition mixed with the bubble forming gas is not particularly limited, and a known bubble mixing method is used. be able to. For example, as an example of a bubble mixing device, a stator having a large number of fine teeth on a disk having a through hole in the center, and a rotor facing the stator and having fine teeth similar to the stator on the disk And the like. Between the teeth on the stator and the teeth on the rotor in such a bubble mixing device, a composition for forming a viscoelastic body layer before mixing bubbles (hereinafter referred to as “a composition precursor for forming a viscoelastic body layer”). ) And a gas component for forming bubbles (bubble forming gas) is introduced into the composition precursor for forming a viscoelastic layer through the through holes while rotating the rotor at a high speed. Thereby, a composition for forming a viscoelastic body layer in which bubbles are finely dispersed and mixed is obtained.

  By applying the composition in which the bubble-forming gas is mixed in this manner onto a predetermined surface and curing the composition, the bubble-containing viscoelastic layer can be formed. As the curing method, a heating method, a method of irradiating active energy rays (for example, ultraviolet rays), or the like can be preferably employed. Viscoelastic material layer forming composition mixed with bubble forming gas is heated and irradiated with actinic energy rays, etc., and cured in a state where bubbles are stably held, thereby suitably forming bubble-containing viscoelastic material layer can do.

  A surfactant may be added to the composition for forming a viscoelastic body layer from the viewpoint of mixing of the bubble forming gas and stability of the bubbles. Examples of such surfactants include ionic surfactants, hydrocarbon surfactants, silicone surfactants, and fluorine surfactants. Of these, fluorine surfactants are preferable, and fluorine surfactants having an oxyalkylene group (typically an oxyalkylene group having 2 to 3 carbon atoms) and a fluorinated hydrocarbon group in the molecule are particularly preferable. A fluorine-type surfactant can be used individually by 1 type or in combination of 2 or more types. As a commercially available fluorosurfactant that can be preferably used, trade name “Surflon S-393” manufactured by AGC Seimi Chemical Co., Ltd. is exemplified.

  The usage-amount of surfactant is not specifically limited, For example, it is set as about 0.01-3 mass parts on a solid content basis with respect to 100 mass parts of acrylic polymers contained in a viscoelastic body layer (B). it can.

  Further, the viscoelastic layer (B) may contain a colorant (pigment, dye, etc.) as long as the object of the present invention is not impaired. The colorant can be blended in the viscoelastic layer (B) as necessary in order to impart optical properties (for example, light-shielding properties) and design properties.

  The colorant is not particularly limited. For example, when the viscoelastic body layer (B) is provided with a light-shielding property, carbon black (for example, acetylene black, ketjen black, furnace black, channel black, thermal black) Black) is preferably used. The amount of carbon black used (upper limit) is suitably, for example, 10% by mass or less, and preferably 5% by mass or less, based on the whole viscoelastic layer (B).

  For example, when the viscoelastic material layer forming composition is cured by a photopolymerization method to form the viscoelastic material layer (B), the photopolymerization is not alienated to color the viscoelastic material layer (B). These pigments (color pigments) can be used as a colorant. When black is desired as the coloring of the viscoelastic layer (B), for example, carbon black can be preferably used as the colorant. The amount of carbon black used (upper limit) is, for example, suitably 10% by mass or less of the entire viscoelastic layer (B) in consideration of the degree of coloring, photopolymerization reactivity, and the like. % Or less is preferable.

  In addition to the acrylic polymer (b), the viscoelastic layer forming composition for forming the viscoelastic layer (B) is an acrylic polymer (for example, the monomer component described above) as a completely polymerized monomer component. An acrylic polymer having a polymerization conversion rate of 95% by mass or more may be included. For example, it may be in the form of a solvent-type composition containing such an acrylic polymer in an organic solvent, a water-dispersed composition in which the acrylic polymer is dispersed in an aqueous solvent, and the like.

  The composition for forming a viscoelastic body layer (B) for forming the viscoelastic body layer (B) contains a crosslinking agent in order to adjust the cohesive force of the viscoelastic body layer (B) according to the use of the pressure-sensitive adhesive sheet. You may go out. For example, use an epoxy crosslinking agent, an isocyanate crosslinking agent, a silicone crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a silane crosslinking agent, an alkyl etherified melamine crosslinking agent, a metal chelate crosslinking agent, etc. Can do.

  In addition, the composition for forming the viscoelastic layer (B) is a known addition of a plasticizer, a softener, an antioxidant, a leveling agent, a stabilizer, a preservative, etc., unless the object of the present invention is impaired. An agent may be included as necessary.

(Formation method of viscoelastic body layer (B))
The viscoelastic body layer (B) can be formed by the same method as the pressure-sensitive adhesive layer (A) described above. For example, when using the composition for forming a viscoelastic body layer, a monomer composition composed of each monomer component used for forming the acrylic polymer (b), and a polymerization initiator for polymerizing the monomer component; It is preferable to use a curable viscoelastic material layer-forming composition containing a mixture with other components added as necessary. In particular, the composition for forming a viscoelastic body layer is preferably a photocurable viscoelastic body layer forming composition using a photopolymerization initiator as the polymerization initiator.

  Since the monomer composition containing (meth) acrylic acid alkyl ester or the like is usually in a liquid state, the monomer component contained in the monomer composition in advance is the same as in forming the pressure-sensitive adhesive layer (A). A partially polymerized syrup-like composition is preferred. Other components for forming the above-described viscoelastic body layer (B) are added to the syrup-like composition as necessary to prepare a curable viscoelastic body layer forming composition.

  When preparing a bubble-containing viscoelastic body layer, as described above, (1) a method of curing a viscoelastic body layer forming composition in which a bubble-forming gas is mixed in advance, and (2) a foaming agent The viscoelastic body layer (B) can be formed by appropriately selecting a method of forming bubbles from the foaming agent using the viscoelastic body layer forming composition.

  The polymerization method for obtaining the syrup composition is not particularly limited, and various polymerization methods as described above can be appropriately selected and used. From the viewpoints of efficiency and simplicity, a photopolymerization method can be preferably employed. The prepared curable viscoelastic body layer forming composition is applied in a layer form on a suitable support such as a substrate or a release liner, as in the case of forming the pressure-sensitive adhesive layer (A). In accordance with the drying step, the resin is cured. When the composition for forming a viscoelastic body layer contains a thermal polymerization initiator as a polymerization initiator, it is heated, and when it contains a photopolymerization initiator, it is irradiated with active energy rays such as ultraviolet rays. The polymerization reaction is started and curing is performed. The active energy ray may be irradiated from one side of the layered viscoelastic material layer forming composition or from both sides. Thus, the viscoelastic body layer sheet | seat provided with the viscoelastic body layer (B) which can be utilized for the adhesive sheet of this invention can be obtained.

(Thickness of viscoelastic layer (B))
The thickness (lower limit) of the viscoelastic layer (B) is typically 200 μm or more. Since the viscoelastic body layer (B) is a viscoelastic body, it is excellent in flexibility. Therefore, by supporting the pressure-sensitive adhesive layer (A) with the viscoelastic body layer (B), the surface (pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer (A) can be suitably adhered to the adherend. As thickness of a viscoelastic body layer (B), 200 micrometers or more are preferable and 300 micrometers or more (for example, 400 micrometers or more) are more preferable. The thickness of the viscoelastic layer (B) can be 500 μm or more, and may be 700 μm or more. The technique disclosed here can also be preferably implemented in an embodiment in which the thickness of the viscoelastic layer (B) is 1 mm or more. The upper limit of the thickness of the viscoelastic layer (B) is not particularly limited, and can be, for example, about 10 mm or less. From the viewpoint of easy formation of the viscoelastic layer (B), cohesiveness, and the like, the thickness of the viscoelastic layer (B) is usually suitably 5 mm or less, and preferably 3 mm or less (for example, 2 mm or less).

[Adhesive sheet]
(Release liner)
The surface (adhesive surface) of the adhesive layer (A) in the adhesive sheet may be protected by a release liner until use. In the case of a double-sided pressure-sensitive adhesive sheet, each pressure-sensitive adhesive surface may be protected by a separate release liner, or each pressure-sensitive adhesive surface may be protected by a single release liner in a form wound in a roll shape. . The release liner is used as a protective material for the adhesive surface, and is peeled off when it is attached to an adherend. The release liner is not necessarily provided on the double-sided pressure-sensitive adhesive sheet.

  A conventional release paper or the like can be used as the release liner, and is not particularly limited. As the release liner, for example, a substrate having a release treatment layer, a low adhesive substrate made of a fluoropolymer, a low adhesive substrate made of a nonpolar polymer, or the like can be used. As a base material which has the said peeling process layer, the base material surface-treated by peeling processing agents, such as a silicone type, a long-chain alkyl type, a fluorine type, molybdenum sulfide, is mentioned, for example. Examples of the fluorine-based polymer in the low-adhesive substrate made of the fluoropolymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chloro Examples include fluoroethylene-vinylidene fluoride copolymer. Examples of the nonpolar polymer include olefinic resins (for example, polyethylene and polypropylene).

  Examples of the substrate to be surface-treated with the release treatment agent include polyester films such as polyethylene terephthalate; olefin resin films such as polyethylene films and polypropylene films; polyvinyl chloride films; polyimide films; polyamide films such as nylon films; Plastic films such as rayon films, foam sheets made of foams such as polyurethane foam, woven and non-woven fabrics made of various fibrous materials alone or blended, metal foil such as aluminum foil and copper foil, fine paper, Japanese paper Papers such as kraft paper, glassine paper, synthetic paper, and top coat paper. Among these, from the viewpoint of processability, a polyester film or paper is preferable, and polyethylene terephthalate is more preferable.

  The release liner can be formed by a known or common method. Further, the thickness of the release liner is not particularly limited.

  Further, the pressure-sensitive adhesive sheet may be in a form provided with a support base material or the like. Examples of the support substrate include plastic films such as polypropylene film, ethylene-propylene copolymer film, polyester film, and polyvinyl chloride film; foam sheet made of foam such as polyurethane foam, polyethylene foam, and polychloroprene foam; Woven and non-woven fabrics (Japanese paper, fine paper) of various fibrous materials (natural fibers such as hemp and cotton, synthetic fibers such as polyester and vinylon, semi-synthetic fibers such as acetate, etc.) alone or blended Etc.); metal foils such as aluminum foil and copper foil; etc. can be appropriately selected and used depending on the application of the pressure-sensitive adhesive sheet. As the plastic film (typically a non-porous plastic film, which is a concept distinguished from a woven fabric or a non-woven fabric), any of an unstretched film and a stretched (uniaxially stretched or biaxially stretched) film is used. Can also be used.

  The thickness of the supporting substrate can be appropriately selected according to the purpose, but is generally about 2 μm to 500 μm, and generally about 10 μm to 200 μm can be preferably used. In addition, when a support base material is a foam sheet, the upper limit of the thickness of this support base material can be about 10 cm, for example, and it is suitable that it is usually about 5 cm (for example, about 2 cm).

(Configuration example of adhesive sheet)
Here, the typical structural example of an adhesive sheet is typically shown in FIG. The pressure-sensitive adhesive sheet 300 shown in FIG. 1 is a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive surfaces on both sides, and one pressure-sensitive adhesive layer (A) 10 constituting the first pressure-sensitive adhesive surface is formed on the surface of the viscoelastic body layer (B). The pressure-sensitive adhesive layer (A) 10 that is supported and constitutes the second pressure-sensitive adhesive surface is supported on the back surface of the viscoelastic layer (B). The first adhesive surface and the second adhesive surface are protected by release liners 120 and 120, respectively.

  In the pressure-sensitive adhesive sheet 300 having such a configuration, both the front and back pressure-sensitive adhesive surfaces that appear when the release liners 120 and 120 are peeled are higher than adherends having various polarities (high polarity and low polarity). Can exhibit adhesive strength. Moreover, since the adhesive sheet 300 includes a thick viscoelastic body layer (B) (typically having a thickness of more than 200 μm), it can be excellent in flexibility. Taking advantage of such features, the pressure-sensitive adhesive sheet 300 can be applied to a wide range of adherends, for example, both of the front and back sides, and is highly versatile for firmly joining various adherends to each other. It can be used as an adhesive sheet.

  The pressure-sensitive adhesive sheet may be implemented as a double-sided pressure-sensitive adhesive sheet having a structure in which only the pressure-sensitive adhesive layer (A) is provided on either the front or back surface of the viscoelastic body layer (B) that is a pressure-sensitive adhesive layer. it can. In such a double-sided pressure-sensitive adhesive sheet, the pressure-sensitive adhesive surface formed by the pressure-sensitive adhesive layer (A) can exhibit a high adhesive force on a wide range of adherends. Moreover, since a thick viscoelastic body layer (B) is included, it can become the thing excellent in the softness | flexibility. Taking advantage of such features, the pressure-sensitive adhesive sheet is composed of the pressure-sensitive adhesive layer (A) after the pressure-sensitive adhesive surface constituted by the viscoelastic body layer (B) is attached to an adherend that matches the characteristics. The adhesive surface can be preferably used in a mode where it is affixed to various adherends as desired.

  Moreover, as described above, the viscoelastic body layer (B) provided in the pressure-sensitive adhesive sheet may contain hollow particles, may contain bubbles, or may contain both bubbles and hollow particles. Preferred examples from the viewpoint of weight reduction of the pressure-sensitive adhesive sheet include a structure in which the viscoelastic body layer (B) includes at least one of bubbles and hollow particles, a structure in which the viscoelastic body layer (B) includes at least hollow particles, and a viscoelastic body. The aspect etc. in which a layer (B) contains both a bubble and a hollow particle are mentioned.

  The hollow particles and bubbles contained in the viscoelastic layer (B) may reduce the surface smoothness of the viscoelastic layer (B) depending on the size and content. When the smoothness of the surface of the viscoelastic body layer (B) is lowered, for example, when the viscoelastic body layer (B) is an adhesive layer and the surface is directly attached to the adherend, the adhesion to the adherend is reduced. It may become deficient and the peel strength may tend to decrease. In the pressure-sensitive adhesive sheet according to this embodiment, the pressure-sensitive adhesive layer (A) constituting the pressure-sensitive adhesive surface is disposed on both surfaces of the viscoelastic body layer (B). Therefore, the adhesion between the adherend and the adhesive surface is not easily affected by the surface smoothness of the viscoelastic layer (B). For this reason, it is easy to adjust the content ratio of the hollow particles and bubbles in the viscoelastic body layer (B), and an adhesive sheet having a better performance balance can be suitably realized.

  In the pressure-sensitive adhesive sheet, each of the pressure-sensitive adhesive layer (A) and the viscoelastic layer (B) may have a single-layer structure or a multilayer structure of two or more layers (that is, a structure including a plurality of layers). May be. Moreover, unless the objective of this invention is impaired, the adhesive layer (A) which is not exposed to the surface of an adhesive sheet (namely, does not comprise an adhesive surface) other than the adhesive layer (A) which comprises an adhesive surface is included. You may go out. In addition, the pressure-sensitive adhesive sheet may include other layers such as an intermediate layer and an undercoat layer as long as the object of the present invention is not impaired.

(Relationship between the thickness of the pressure-sensitive adhesive layer (A) and the thickness of the viscoelastic layer (B))
The relationship between the thickness of the pressure-sensitive adhesive layer (A) and the thickness of the viscoelastic body layer (B) is not particularly limited, but in the pressure-sensitive adhesive sheet, the thickness (lower limit) of the viscoelastic body layer (B) is It is preferable that the thickness is larger than the thickness of the pressure-sensitive adhesive layer (A). Usually, it is appropriate to make it 1.5 times or more, preferably 2 times or more, more preferably 3 times or more (for example, 5 times or more).

  Thus, by making a viscoelastic body layer (B) comparatively thick, the effect that an adhesive sheet contains a viscoelastic body layer (B) can be exhibited better. In addition, the thickness (upper limit) of the viscoelastic layer (B) can be, for example, 50 times or less the thickness of the pressure-sensitive adhesive layer (A), from the viewpoint of the balance between peel strength and cohesiveness. Usually, it is appropriate to make it 20 times or less, and preferably 10 times or less.

  The total thickness (lower limit) of the adhesive sheet, excluding the release liner and the supporting substrate, which is used by adhering to the adherend (layer including the adhesive layer (A) and the viscoelastic layer (B)) The value) is typically more than 200 μm, more preferably 300 μm or more, further preferably 400 μm or more, and particularly preferably 500 μm or more (for example, 700 μm or more). The pressure-sensitive adhesive sheet can also be preferably implemented in an embodiment in which the total thickness of the parts used by being attached to the adherend exceeds 1 mm. The upper limit of the total thickness of the same portion is not particularly limited, and can be, for example, about 15 mm or less, usually about 10 mm or less, preferably 7 mm or less, more preferably 5 mm or less (for example, 3 mm or less).

(Adherent)
The pressure-sensitive adhesive sheet can be preferably used in a mode in which the pressure-sensitive adhesive surface comprising the pressure-sensitive adhesive layer (A) is attached to various adherends. The pressure-sensitive adhesive sheet is, for example, a polyolefin resin such as polyethylene (PE) resin or polypropylene (PP) resin, acrylonitrile butadiene styrene copolymer (ABS) resin, high impact polystyrene (HIPS) resin, polycarbonate (PC) resin, PC Wide range of adherends from low-polarity adherends made of resin, such as polymer blend (PC / ABS) resin with ABS, to high-polarity adherends made of metal, such as stainless steel Can exhibit high adhesive strength.

  Moreover, since the pressure-sensitive adhesive sheet has a thickness exceeding 200 μm by including the viscoelastic body layer (B) and has high flexibility (easy to be deformed), unevenness that may be present on the surface in joining various members, Curved surfaces or manufacturing errors of members can be absorbed by deformation of the adhesive, and the members can be joined with high reliability.

  Furthermore, the pressure-sensitive adhesive sheet can express a high adhesive force with respect to a wide range of adherends ranging from adherends with high polarity to adherends with low polarity. Therefore, in joining various members, desired members can be joined regardless of the polarities of the materials constituting the members.

  As mentioned above, the adhesive sheet of this embodiment can be used for various uses, such as joining between members in various OA equipment, household appliances, automobiles, etc. (for example, fixing use of various parts in such products). Moreover, since an adhesive sheet can express favorable adhesive force with respect to a wide range of adherends, it is not restricted by the material of the target member. Therefore, it is not necessary to use the pressure sensitive adhesive sheet properly, and it can be used very conveniently.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited at all by these Examples.

[Example 1]
(Preparation of syrup I)
As a monomer component, a liquid monomer mixture comprising 78 parts by mass of 2-ethylhexyl acrylate (2EHA), 18 parts by mass of N-vinyl-2-pyrrolidone (NVP) and 4 parts by mass of 2-hydroxyethyl acrylate (HEA) ( Monomer composition) as a photopolymerization initiator, trade name “Irgacure 651 (2,2-dimethoxy-1,2-diphenylethane-1-one)” (manufactured by BASF Japan Ltd.) 0.05 parts by mass and product After blending 0.05 part by mass of the name “Irgacure 184 (1-hydroxycyclohexyl phenyl ketone)” (manufactured by BASF Japan Ltd.), the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature: 30 ° C.) is about A part of the monomer component is polymerized by irradiating with ultraviolet rays until it reaches 15 Pa · s. Minute polymer (polymerization ratio: 10 wt%) was prepared syrup I containing (2EHA / NVP / HEA = 78/18/4).

(Preparation of pressure-sensitive adhesive layer forming composition 101)
To 100 parts by mass of syrup I, 4 parts by mass of acrylic acid (AA) and 0.120 parts by mass of 1,6-hexanediol diacrylate (HDDA) were added to obtain a mixture of the syrup. Furthermore, as a photopolymerization initiator for an additional amount, a trade name “Irgacure 651 (2,2-dimethoxy-1,2-diphenylethane-1-one)” (manufactured by BASF Japan Ltd.) 0.5 mass Parts were added. In addition, as an additional component, 1 part by mass of trade name “AT DN101 Black” (manufactured by Dainichi Seika Kogyo Co., Ltd.), which is a black pigment, was added to the mixture. And the composition 101 for adhesive layer formation was obtained by fully mixing these.

(Preparation of adhesive layer sheet 111)
As a release liner, two sheets of a polyethylene terephthalate base material (trade name “MRF”, manufactured by Mitsubishi Polyester Film Co., Ltd., or product name “MRN”, manufactured by Mitsubishi Polyester Film Co., Ltd.), one side of which was subjected to a release treatment, were prepared. . The said adhesive layer forming composition 101 was apply | coated to the peeling process surface of the 1st release liner, and the coating layer was obtained. On this coating layer, the 2nd release liner was bonded together in the form which the peeling process surface of a coating layer and a release liner touched.

Next, the coating layer was irradiated with ultraviolet rays having an illuminance of 5 mW / cm ² from both sides for 3 minutes to cure the coating layer to obtain a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) having a thickness of 200 μm. In addition, “Black Light” manufactured by Toshiba Corporation was used as a source of ultraviolet rays. Further, the illuminance of ultraviolet rays was adjusted using an industrial UV checker having a peak sensitivity wavelength of about 350 nm (trade name “UVR-T1”, manufactured by Topcon Co., Ltd., light receiving unit type UD-T36, maximum sensitivity: 350 nm). As described above, the pressure-sensitive adhesive layer sheet 111 (release liner / pressure-sensitive adhesive layer A1 / release liner) in which the pressure-sensitive adhesive layer A1 having a thickness of 200 μm was supported between the two release liners was produced.

[Measurement of solvent insoluble fraction]
It was 68 mass% when the solvent insoluble content rate (mass%) of obtained adhesive layer A1 was calculated | required with the following method.

A predetermined amount of the pressure-sensitive adhesive layer (initial mass W1) was immersed in an ethyl acetate solution and allowed to stand at room temperature for 1 week. Then, the insoluble matter was taken out and dried, and the mass (W2) was measured. Asking.
Solvent insoluble fraction (% by mass) = (W2 / W1) × 100

(Preparation of syrup II)
As a monomer component, a monomer mixture consisting of 85 parts by mass of 2-ethylhexyl acrylate (2EHA) and 15 parts by mass of acrylic acid (AA) was added as a photopolymerization initiator, under the trade name “Irgacure 651” (2,2-dimethoxy-1, 2-diphenylethane-1-one) ”(manufactured by BASF) and 0.05 part by mass of the trade name“ Irgacure 184 (1-hydroxycyclohexyl phenyl ketone) ”(manufactured by BASF) Irradiate ultraviolet rays (UV) until the viscosity (BH viscometer No. 5 rotor, 10 rpm, measurement temperature: 30 ° C.) reaches about 15 Pa · s, and a partial aggregate obtained by polymerizing a part of the monomer components is obtained. Containing syrup II (2EHA / AA = 85/15) was prepared.

(Preparation of viscoelastic body layer forming composition 201)
100 parts by mass of syrup II, 0.15 parts by mass of dipentaerythritol hexaacrylate (DPHA) and a hollow glass balloon (average particle size 40 μm, trade name “Fuji Balloon H-40”, manufactured by Fuji Silysia Chemical Ltd.) 15 parts by mass was added to obtain a composition 201 for forming a viscoelastic body layer.

(Preparation of viscoelastic layer sheet 211)
Two release liners similar to those used for the production of the pressure-sensitive adhesive layer sheet 111 were prepared. 0.03 parts by mass of “Irgacure 651” is added to 100 parts by mass of the composition 201 for forming a viscoelastic body layer, and this is applied to the release treatment surface of the first release liner. Obtained. On this coating layer, the 2nd release liner was bonded together in the form which the peeling process surface of a coating layer and a release liner touched.

Next, the coating layer was irradiated with ultraviolet rays having an illuminance of 5 mW / cm ² from both sides for 3 minutes to cure the coating layer to obtain a viscoelastic layer. In addition, for the irradiation and measurement of ultraviolet rays, the same as that used in the production of the pressure-sensitive adhesive layer sheet 111, Toshiba Corporation, trade name “Black Light” and Topcon Corporation, trade name “UVR-T1” were used. .

  As described above, the viscoelastic body layer sheet 211 in which the viscoelastic body layer B1 having a thickness of 800 μm was supported between the two release liners was produced. This viscoelastic layer B1 is a viscoelastic layer that contains hollow particles but does not contain bubbles, and has adhesiveness.

(Preparation of laminated double-sided PSA sheet 301)
The release liner on one side of the viscoelastic layer sheet 211 was peeled off, and the adhesive layer A1 from which the release liner on one side of the adhesive layer sheet 111 was peeled was bonded using a laminator (200 mm / min, 0.2 MPa). . Further, the release liner on the other side of the viscoelastic layer sheet 211 was peeled off, and the adhesive layer A1 from which the release liner on one side of another pressure-sensitive adhesive layer sheet 111 was peeled was bonded in the same manner.

  Thus, a laminated double-sided pressure-sensitive adhesive sheet 301 (release liner / adhesive) provided with an adhesive layer A1 having a thickness of 200 μm on both sides of a viscoelastic layer B1 having a thickness of 800 μm and the outermost layers on both the front and back surfaces thereof protected by the release liner. A laminated double-sided PSA sheet having a laminated structure of agent layer A1 / viscoelastic layer B1 / adhesive layer A1 / release liner) was obtained. This laminated double-sided PSA sheet has a schematic cross section as shown in FIG.

[Example 2]
In preparing the composition for forming the pressure-sensitive adhesive layer, 0.030 part by mass of HDDA was used instead of 0.120 part by mass of HDDA, and an additional part was substituted for 0.5 part by mass of the photopolymerization initiator (Irgacure 651). A composition 102 for forming an adhesive layer was prepared using syrup I in the same manner as the composition 101 for forming an adhesive layer of Example 1 except that 0.3 parts by mass of a photopolymerization initiator (Irgacure 651) was used. Prepared.

  Next, the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive layer A2 is the same as the pressure-sensitive adhesive layer sheet 111 of Example 1 except that the pressure-sensitive adhesive layer forming composition 102 is used instead of the pressure-sensitive adhesive layer forming composition 101. A sheet 112 was produced. The thickness of the pressure-sensitive adhesive layer A2 was 207 μm. Moreover, when the solvent-insoluble fraction (mass%) of adhesive layer A2 was calculated | required like Example 1, it was 14 mass%.

  Furthermore, a thickness of 800 μm is obtained in the same manner as in Example 1 except that the adhesive layer sheet 112 is used instead of the adhesive layer sheet 111 by using the viscoelastic body layer sheet 211 including the viscoelastic body layer B1. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 2) in which a pressure-sensitive adhesive layer A2 having a thickness of 207 μm was held on both surfaces of the viscoelastic body layer B1 was obtained.

Example 3
In preparing the composition for forming the pressure-sensitive adhesive layer, 0.056 parts by mass of HDDA was used instead of 0.120 parts by mass of HDDA, and 0.5 parts by mass of an additional photopolymerization initiator (Irgacure 651) was added. That 0.7 parts by weight of the photopolymerization initiator (Irgacure 651) was used, 0.8 parts by weight of black pigment (AT DN101 black) was used instead of 1 part by weight of black pigment (AT DN101 black), and Other than adding 4 parts by mass of hollow glass balloon (average particle size 45 μm, specific gravity 0.25 g / cm ³ , trade name “Sphericel (registered trademark) 25P45 (silicate glass)” (manufactured by Potters Barotini Co., Ltd.) In the same manner as the pressure-sensitive adhesive layer forming composition 101 of Example 1, a pressure-sensitive adhesive layer forming composition 103 was prepared using syrup I.

  Next, the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive layer A3 is the same as the pressure-sensitive adhesive layer sheet 111 of Example 1 except that the pressure-sensitive adhesive layer forming composition 103 is used instead of the pressure-sensitive adhesive layer forming composition 101. A sheet 113 was produced. The thickness of the pressure-sensitive adhesive layer A3 was 212 μm. Moreover, the solvent insoluble fraction (mass%) of adhesive layer A3 was 56 mass%.

  Furthermore, a thickness of 800 μm is obtained in the same manner as in Example 1 except that the adhesive layer sheet 113 is used instead of the adhesive layer sheet 111 by using the viscoelastic body layer sheet 211 including the viscoelastic body layer B1. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 3) in which a 212 μm-thick pressure-sensitive adhesive layer A3 was held on both surfaces of the viscoelastic layer B1 was obtained.

Example 4
In preparing the composition for forming the pressure-sensitive adhesive layer, 0.030 part by mass of HDDA was used instead of 0.120 part by mass of HDDA, and an additional part was substituted for 0.5 part by mass of an additional photopolymerization initiator (Irgacure 651). Except that 0.3 parts by weight of the photopolymerization initiator (Irgacure 651) was used, and 0.8 parts by weight of black pigment (AT DN101 black) was used instead of 1 part by weight of black pigment (AT DN101 black) Prepared a pressure-sensitive adhesive layer forming composition 104 using syrup I in the same manner as the pressure-sensitive adhesive layer forming composition 101 of Example 1.

  Next, the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive layer A4 is the same as the pressure-sensitive adhesive layer sheet 111 of Example 1 except that the pressure-sensitive adhesive layer forming composition 104 is used instead of the pressure-sensitive adhesive layer forming composition 101. A sheet 114 was produced. The thickness of the pressure-sensitive adhesive layer A4 was 207 μm. Moreover, the solvent insoluble fraction (mass%) of adhesive layer A4 was 41 mass%.

  Furthermore, a thickness of 800 μm is obtained in the same manner as in Example 1 except that the adhesive layer sheet 114 is used instead of the adhesive layer sheet 111 using the viscoelastic body layer sheet 211 including the viscoelastic body layer B1. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 4) in which a pressure-sensitive adhesive layer A4 having a thickness of 207 μm was held on both surfaces of the viscoelastic layer B1 was obtained.

Example 5
In preparing the pressure-sensitive adhesive layer-forming composition, 0.025 parts by mass of HDDA was used instead of 0.120 parts by mass of HDDA, and black pigment (AT DN101 black) was changed to 1 part by mass of black pigment (AT DN101 black). Except having used 3 mass parts, it carried out similarly to the composition 101 for adhesive layer formation of Example 1, and prepared the composition 105 for adhesive layer formation using the syrup I.

  Next, the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive layer A5 is the same as the pressure-sensitive adhesive layer sheet 111 of Example 1 except that the pressure-sensitive adhesive layer forming composition 105 is used instead of the pressure-sensitive adhesive layer forming composition 101. A sheet 115 was produced. The thickness of the pressure-sensitive adhesive layer A5 was 200 μm. Moreover, when the solvent-insoluble fraction (mass%) of adhesive layer A5 was calculated | required like Example 1, it was 35 mass%.

  Furthermore, a thickness of 800 μm is obtained in the same manner as in Example 1 except that the adhesive layer sheet 115 is used instead of the adhesive layer sheet 111 using the viscoelastic body layer sheet 211 including the viscoelastic body layer B1. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 5) in which the pressure-sensitive adhesive layer A5 having a thickness of 200 μm was held on both surfaces of the viscoelastic body layer B1 was obtained.

Example 6
Except that 0.025 parts by mass of HDDA was used instead of 0.120 parts by mass of HDDA in the preparation of the pressure-sensitive adhesive layer forming composition, and that no additional photopolymerization initiator (Irgacure 651) and black pigment were added. In the same manner as the pressure-sensitive adhesive layer forming composition 101 of Example 1, a pressure-sensitive adhesive layer forming composition 106 was prepared using syrup I.

  Next, the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive layer A6 in the same manner as the pressure-sensitive adhesive layer sheet 111 of Example 1 except that the pressure-sensitive adhesive layer forming composition 106 was used instead of the pressure-sensitive adhesive layer forming composition 101. A sheet 116 was produced. The thickness of the pressure-sensitive adhesive layer A6 was 145 μm. Moreover, the solvent insoluble fraction (mass%) of adhesive layer A6 was 82 mass%.

  Furthermore, a thickness of 800 μm is obtained in the same manner as in Example 1 except that the viscoelastic body layer sheet 211 including the viscoelastic body layer B1 is used and the adhesive layer sheet 116 is used instead of the adhesive layer sheet 111. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 6) in which a pressure-sensitive adhesive layer A6 having a thickness of 145 μm was held on both surfaces of the viscoelastic body layer B1 was obtained.

[ Reference Example 7 ]
In preparing the pressure-sensitive adhesive layer forming composition, AA 1 part by mass was used instead of AA 4 parts by mass, HDDA 0.025 parts by mass was used instead of HDDA 0.120 parts by mass, and an additional photopolymerization initiator ( A pressure-sensitive adhesive layer forming composition 107 was prepared using syrup I in the same manner as the pressure-sensitive adhesive layer forming composition 101 of Example 1 except that Irgacure 651) and the black pigment were not added.

  Next, in place of the pressure-sensitive adhesive layer forming composition 101, the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive layer A7 was used in the same manner as the pressure-sensitive adhesive layer sheet 111 of Example 1 except that the pressure-sensitive adhesive layer forming composition 107 was used. An agent layer sheet 117 was produced. The thickness of the pressure-sensitive adhesive layer A7 was 149 μm. Moreover, the solvent insoluble content rate (mass%) of adhesive layer A7 was 80 mass%.

Furthermore, a thickness of 800 μm is obtained in the same manner as in Example 1 except that the viscoelastic body layer sheet 211 including the viscoelastic body layer B1 is used and the adhesive layer sheet 117 is used instead of the adhesive layer sheet 111. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Reference Example 7 ) in which a pressure-sensitive adhesive layer A7 having a thickness of 149 μm was held on both surfaces of the viscoelastic layer B1 was obtained.

[ Reference Example 8 ]
In preparing the pressure-sensitive adhesive layer forming composition, AA, an additional photopolymerization initiator (Irgacure 651), and the black pigment were not added, and the same as the pressure-sensitive adhesive layer forming composition 101 of Example 1. Thus, a pressure-sensitive adhesive layer forming composition 108 was prepared using syrup I.

  Next, the pressure-sensitive adhesive layer containing the pressure-sensitive adhesive layer A8 is the same as the pressure-sensitive adhesive layer sheet 111 of Example 1, except that the pressure-sensitive adhesive layer forming composition 108 is used instead of the pressure-sensitive adhesive layer forming composition 101. A sheet 118 was produced. The thickness of the pressure-sensitive adhesive layer A8 was 144 μm. Moreover, when the solvent-insoluble fraction (mass%) of adhesive layer A8 was calculated | required like Example 1, it was 82 mass%.

Furthermore, a thickness of 800 μm was obtained in the same manner as in Example 1 except that the adhesive layer sheet 118 was used instead of the adhesive layer sheet 111 using the viscoelastic body layer sheet 211 including the viscoelastic body layer B1. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Reference Example 8 ) in which a pressure-sensitive adhesive layer A8 having a thickness of 144 μm was held on both surfaces of the viscoelastic body layer B1 was obtained.

Example 9
In the same manner as in Example 1, a pressure-sensitive adhesive layer sheet 111 including the pressure-sensitive adhesive layer A1 was produced using the pressure-sensitive adhesive layer forming composition 101.

(Preparation of syrup III)
Syrup III in which a part of the monomer mixture was polymerized (2EHA / AA = 90/10) was prepared in the same manner as Syrup II, except that a monomer mixture consisting of 90 parts by mass of 2EHA and 10 parts by mass of AA was used.

(Preparation of viscoelastic body layer forming composition 202)
To 100 parts by mass of syrup III, 0.08 parts by mass of 1,6-hexanediol diacrylate (HDDA) and 12.5 parts by mass of hollow glass balloon “Fuji Balloon H-40” were added to defoam. Processed. After defoaming treatment, a fluorosurfactant (trade name “Surflon S-393”, manufactured by AGC Seimi Chemical Co., Ltd .; acrylic copolymer having polyoxyethylene group and fluorinated hydrocarbon group in the side chain; Mw8300) 0.7 parts by mass was added to obtain a composition precursor for forming a viscoelastic layer.

  The composition precursor for forming the viscoelastic body layer is divided into a stator having a large number of fine teeth on a disk having a through hole in the center, and fine teeth similar to the stator on the disk facing the stator. The composition for forming a viscoelastic material layer 202 in which bubbles are dispersed and mixed is obtained by stirring together with nitrogen gas introduced from the through-hole of the device using a bubble mixing device equipped with a rotor. In addition, it mixed so that a bubble might be about 20 volume% with respect to the whole volume of this composition 202 for bubble-containing viscoelastic body layer formation.

(Preparation of viscoelastic layer sheet 212)
Two release liners similar to those used for the production of the pressure-sensitive adhesive layer sheet 111 were prepared. 0.04 parts by mass of “Irgacure 651” is added to 100 parts by mass of the composition 202 for forming a viscoelastic body layer containing the bubbles, and an antioxidant (trade name “Irganox 1010, manufactured by BASF AG”) is further added. “) 0.5 part by mass and pigment (manufactured by Dainichi Seika Co., Ltd., trade name“ AT DN101 Black ”) 0.02 part by mass were added and mixed. This was cured by ultraviolet irradiation in the same manner as the viscoelastic material layer sheet 211 to form a viscoelastic material layer sheet 212 in which a viscoelastic material layer B2 having a thickness of 800 μm was supported between two release liners. This viscoelastic body layer B2 is a viscoelastic body layer containing hollow particles and bubbles, and is an adhesive layer having adhesiveness.

(Preparation of laminated double-sided PSA sheet 309)
The release liner on one side of the viscoelastic layer sheet 212 was peeled off, and the adhesive layer A1 from which the release sheet on one side of the adhesive layer sheet 111 was peeled was bonded using a laminator (200 mm / min, 0.2 MPa). . Further, the release liner on the other side of the viscoelastic layer sheet 212 was peeled off, and the adhesive layer A1 from which the release sheet on one side of another pressure-sensitive adhesive layer sheet 111 was peeled was bonded in the same manner. Thus, a laminated double-sided pressure-sensitive adhesive sheet 309 having a pressure-sensitive adhesive layer A1 having a thickness of 200 μm on both sides of a viscoelastic layer B2 having a thickness of 800 μm and a release liner on both front and back surfaces (release liner / pressure-sensitive adhesive layer A1 / A laminated double-sided PSA sheet having a laminated structure of viscoelastic layer B2 / adhesive layer A1 / release liner) was obtained. This laminated double-sided pressure-sensitive adhesive sheet 309 is referred to as a sheet of Example 9.

Example 10
Similarly to Example 2, a pressure-sensitive adhesive layer sheet 112 including the pressure-sensitive adhesive layer A2 was produced using the pressure-sensitive adhesive layer forming composition 102. Further, the viscoelastic body layer sheet 212 including the viscoelastic body layer B2 is used in the same manner as in Example 9 except that the adhesive layer sheet 112 is used instead of the adhesive layer sheet 111, and the thickness is 800 μm. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 10) in which a pressure-sensitive adhesive layer A2 having a thickness of 207 μm was held on both surfaces of the viscoelastic body layer B2 was obtained.

Example 11
Similarly to Example 3, a pressure-sensitive adhesive layer sheet 113 including a pressure-sensitive adhesive layer A3 was produced using the pressure-sensitive adhesive layer forming composition 103. Further, the viscoelastic body layer sheet 212 including the viscoelastic body layer B2 is used in the same manner as in Example 9 except that the adhesive layer sheet 113 is used instead of the adhesive layer sheet 111, and the thickness is 800 μm. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 11) in which a 212 μm-thick pressure-sensitive adhesive layer A3 was held on both surfaces of the viscoelastic layer B2 was obtained.

Example 12
Similarly to Example 4, a pressure-sensitive adhesive layer sheet 114 including a pressure-sensitive adhesive layer A4 was produced using the pressure-sensitive adhesive layer forming composition 104. Furthermore, except that the adhesive layer sheet 114 was used instead of the adhesive layer sheet 111, the viscoelastic body layer sheet 212 including the viscoelastic body layer B2 was used in the same manner as in Example 9, and the thickness was 800 μm. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 12) in which a pressure-sensitive adhesive layer A4 having a thickness of 207 μm was held on both surfaces of the viscoelastic layer B2 was obtained.

Example 13
In the same manner as in Example 5, a pressure-sensitive adhesive layer sheet 115 including a pressure-sensitive adhesive layer A5 was produced using the pressure-sensitive adhesive layer forming composition 105. Further, the viscoelastic body layer sheet 212 including the viscoelastic body layer B2 is used in the same manner as in Example 9 except that the adhesive layer sheet 115 is used instead of the adhesive layer sheet 111, and the thickness is 800 μm. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 13) in which a pressure-sensitive adhesive layer A5 having a thickness of 200 μm was held on both surfaces of the viscoelastic body layer B2 was obtained.

Example 14
In the same manner as in Example 6, the pressure-sensitive adhesive layer sheet 116 including the pressure-sensitive adhesive layer A6 was produced using the pressure-sensitive adhesive layer forming composition 106. Furthermore, except that the adhesive layer sheet 111 was used instead of the adhesive layer sheet 111, the viscoelastic body layer sheet 212 including the viscoelastic body layer B2 was used in the same manner as in Example 9, and the thickness was 800 μm. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Example 14) in which a 145 μm-thick pressure-sensitive adhesive layer A6 was held on both surfaces of the viscoelastic body layer B2 was obtained.

[ Reference Example 15 ]
In the same manner as in Reference Example 7 , a pressure-sensitive adhesive layer sheet 117 including the pressure-sensitive adhesive layer A7 was produced using the pressure-sensitive adhesive layer forming composition 107. Furthermore, except that the adhesive layer sheet 117 was used instead of the adhesive layer sheet 111, the viscoelastic body layer sheet 212 including the viscoelastic body layer B2 was used in the same manner as in Example 9, and the thickness was 800 μm. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Reference Example 15 ) in which a pressure-sensitive adhesive layer A7 having a thickness of 149 μm was held on both surfaces of the viscoelastic body layer B2 was obtained.

[ Reference Example 16 ]
In the same manner as in Reference Example 8 , a pressure-sensitive adhesive layer sheet 118 including a pressure-sensitive adhesive layer A8 was produced using the pressure-sensitive adhesive layer forming composition 108. Furthermore, except that the adhesive layer sheet 118 was used instead of the adhesive layer sheet 111, the viscoelastic body layer sheet 212 including the viscoelastic body layer B2 was used in the same manner as in Example 9, and the thickness was 800 μm. A laminated double-sided pressure-sensitive adhesive sheet (sheet of Reference Example 16 ) in which a pressure-sensitive adhesive layer A8 having a thickness of 144 μm was held on both surfaces of the viscoelastic body layer B2 was obtained.

[Comparative Example 1]
According to the description in Example 1, a pressure-sensitive adhesive layer sheet 111 including a pressure-sensitive adhesive layer A1 having a thickness of 200 μm was prepared using the pressure-sensitive adhesive layer forming composition 101. This pressure-sensitive adhesive layer sheet 111 (double-sided pressure-sensitive adhesive sheet having the structure of release liner / pressure-sensitive adhesive layer A1 / release liner) was used as the sheet of Comparative Example 1 as it was.

[Comparative Example 2]
In accordance with the description in Example 1, a viscoelastic body layer sheet 211 including a viscoelastic body layer B1 having a thickness of 800 μm was prepared using the composition 201 for forming a viscoelastic body layer. This viscoelastic layer sheet 211 (double-sided pressure-sensitive adhesive sheet having the structure of release liner / viscoelastic layer B1 / release liner) was used as the sheet of Comparative Example 2 as it was.

[Comparative Example 3]
In accordance with the description in Example 9, a viscoelastic body layer sheet 212 including a viscoelastic body layer B2 having a thickness of 800 μm was produced using the viscoelastic body layer forming composition 202. This viscoelastic layer sheet 212 (release liner / viscoelastic layer B2 / double-sided pressure-sensitive adhesive sheet having a release liner structure) was used as the sheet of Comparative Example 3 as it was.

[90 degree peel strength measurement]
The release liner was peeled off from one side of the sheets according to Examples 1 to 16 and Comparative Examples 1 to 3, and then affixed to an aluminum foil having a thickness of 130 μm that had been alumite-treated. A test piece was prepared by cutting the backed adhesive sheet into a width of 25 mm and a length of 70 mm.

  As the adherend, the surfaces of polystyrene (PSt), polycarbonate (PC), acrylonitrile butadiene styrene (ABS) resin plate, and stainless steel (SUS) plate were washed with isopropyl alcohol (IPA). The release liner was peeled from each test piece, the pressure-sensitive adhesive surface was brought into contact with the adherend plate, and the 5-kg roller was reciprocated twice for pressure bonding. After the pressure bonding, it was aged for 20 minutes in an atmosphere of 23 ° C. and 50% RH. After aging, using a tensile tester (manufactured by Shimadzu Corporation, apparatus name “Tensilon”), an adherend (at 23 ° C., 50% RH, tensile speed 300 mm / min, peel angle 90 °) The test piece was peeled from the PP plate and the peel strength (N / 25 mm) at that time was measured.

  The measurement results of the 90 degree peel strength are shown in Table 1. The table also shows the composition of the main components of the pressure-sensitive adhesive layer forming composition used for the production of the sheets of Examples and Comparative Examples. “-” In each table means that the corresponding component is not included (zero), or that the 90-degree peel strength test has not been performed. Moreover, it shows below about the abbreviation described in the table | surface.

2EHA: 2-ethylhexyl acrylate NVP: N-vinyl-2-pyrrolidone HEA: 2-hydroxyethyl acrylate AA: acrylic acid HDDA: 1,6-hexanediol diacrylate PSt: polystyrene SUS: stainless steel PC: polycarbonate ABS: acrylonitrile butadiene Styrene Black pigment: Trade name “AT DN101 Black”

  As shown in Table 1, the peel strength of the pressure-sensitive adhesive sheet (Comparative Example 1) having only the pressure-sensitive adhesive layer A1 is 37.1 N / 25 mm to 45.5 N / 25 mm, and the peel strength for any adherend is 40 N / It was around 25 mm. In addition, the adhesive sheet (Comparative Examples 2 and 3) having only the viscoelastic layer B1 or B2 showed a high peel strength of 60 N / 25 mm or more for SUS, but the peel strength for ABS and PSt was 40 N / 25 mm. Was less than.

  On the other hand, the peel strength of the laminated double-sided pressure-sensitive adhesive sheet of the present invention (Examples 1 and 9) provided with the pressure-sensitive adhesive layer A1 on both sides of the viscoelastic body layer B1 or B2 is almost equal to any adherend. It was 60 N / 25 mm or more, and showed high peel strength. From this, it was confirmed that the laminated double-sided pressure-sensitive adhesive sheet of each Example was able to exhibit high adhesive force on a wide range of adherends including those with low polarity, regardless of the polarity of the adherend. did it.

  The reason why the overall peel strength is improved as compared with the pressure-sensitive adhesive layer (A) only is that it is pressure-bonded to the adherend together with the viscoelastic layer (B) having a certain thickness and flexibility. By adhering the soft pressure-sensitive adhesive layer (A) appropriately into the fine irregularities on the adherend surface, the pressure-sensitive adhesive layer (A) is supported by the viscoelastic body layer (B) from the back side. The adhesive layer (A) is kept in close contact with the adherend surface, and the laminated double-sided PSA sheet has a viscoelastic body layer (B) having a certain thickness and flexibility. It can be considered that resistance can be achieved not by lines but by surfaces.

  The reason why the peel strength for an adherend having a low polarity is improved as compared with the pressure-sensitive adhesive sheet having only the viscoelastic layer (B) is derived from both at least a hydroxyl group-containing monomer and a heterocyclic ring-containing vinyl monomer. As a result of appropriately adjusting the polarity on the contact surface between the pressure-sensitive adhesive sheet and the adherend by providing the surface layer of the laminated double-sided pressure-sensitive adhesive sheet with the pressure-sensitive adhesive layer (A) having the acrylic polymer (a) containing the structural unit It is conceivable that the compatibility (wettability) with respect to a wide range of adherends has improved. That is, by having a polar group, while maintaining good wettability to a highly polar adherend, both the acidic group and the basic group are combined, and the polarity in the pressure-sensitive adhesive layer (A) As a result of the balance, it can be inferred that the wettability to the low-polarity adherend has been improved.

  Next, the result of a 90-degree peel test when a PSt plate having a relatively low polarity is used as an adherend will be described. The peel strength with respect to PSt of the pressure-sensitive adhesive sheets of Comparative Examples 1 to 3 consisting of only one of the pressure-sensitive adhesive layer (A) and the viscoelastic material layer (B) was less than 40 N / 25 mm. On the other hand, the laminated double-sided PSA sheet (PSA sheet of Examples 1 to 16) having B1 or B2 as the viscoelastic body layer (B) and having either of the PSA layers A1 to A18 on both sides thereof, All showed a peel strength of 40 N / 25 mm or more. The peel strength with respect to PSt of the laminated double-sided PSA sheets of Examples 1 to 16 was improved by about 1.1 to 1.7 times compared to the PSA sheet having only the PSA layer A1 (Comparative Example 1). Moreover, compared with the adhesive sheet (comparative example 2 or 3) only of viscoelastic body layer B1 or B2, it improved significantly 1.8 to 3.1 times.

  In the laminated double-sided PSA sheet of the present invention, the pressure-sensitive adhesive sheet using B2 as a viscoelastic body layer was generally higher than the PSA sheet using the viscoelastic body layer B1. The viscoelastic layer B2 contains 20% by volume of bubbles in addition to the hollow particles, and is more flexible than the viscoelastic layer B1. For this reason, as a result of supporting the pressure-sensitive adhesive layer (A) while flexibly deforming so that the pressure-sensitive adhesive layer (A) can be adhered along fine irregularities on the surface of the adherend, it is possible to express high adhesive force. Inferred.

  Moreover, among the laminated double-sided pressure-sensitive adhesive sheets, the pressure-sensitive adhesive sheet prepared by additionally adding a carboxyl group-containing monomer (acrylic acid) to the pressure-sensitive adhesive layer forming composition showed a high peel strength of 45 N / 25 mm or more.

  In particular, the pressure-sensitive adhesive sheet prepared so that the structural unit derived from the carboxyl group-containing monomer in the acrylic polymer (a) was 3.8% by mass or more exhibited a higher peel strength of 47 N / 25 mm.

  Each of the pressure-sensitive adhesive sheets of Examples 1 to 16 was prepared by adding a polyfunctional monomer to the composition for forming a pressure-sensitive adhesive layer. The higher the amount of the polyfunctional monomer added, the higher the peel strength. There was a tendency to show.

  Furthermore, the pressure-sensitive adhesive sheet to which the black pigment was added to the pressure-sensitive adhesive layer and the initiator (Irg651) was additionally added generally showed higher adhesive strength than the pressure-sensitive adhesive sheet prepared without adding them. In a double-sided pressure-sensitive adhesive sheet used industrially, it is preferable to add a colorant or the like in order to impart light-shielding properties and design properties. Therefore, such knowledge can be said to be very useful.

  300 ... laminated double-sided pressure-sensitive adhesive sheet (pressure-sensitive adhesive sheet), 10 ... pressure-sensitive adhesive layer A, 20 ... viscoelastic layer B, 120 ... release liner

Claims (9)

An adhesive layer (A) comprising an acrylic polymer (a) as a base polymer and constituting an adhesive surface;
The viscoelastic layer supporting the adhesive layer (A) and (B), a PSA sheet comprising a
The acrylic polymer (a)
A structural unit derived from one or more acidic group-containing monomers selected from the group consisting of a hydroxyl group-containing monomer and a carboxyl group-containing monomer;
A structural unit derived from any one or more basic group-containing monomers selected from the group consisting of nitrogen-containing heterocyclic ring-containing vinyl monomers and amide group-containing monomers (excluding hydroxyl group-containing monomers and carboxyl group-containing monomers) ; Including
The thickness of the viscoelastic layer (B) is, I der least 200 [mu] m,
The acrylic polymer (a)
4% by mass or more and 15% by mass or less of the structural unit derived from the acidic group-containing monomer, and 3.8% by mass or more of the structural unit derived from the carboxyl group-containing monomer,
A pressure-sensitive adhesive sheet comprising 15% by mass or more and 40% by mass or less of a structural unit derived from the basic group-containing monomer .   The said acryl-type polymer (a) contains 50 mass% or more of structural units derived from the (meth) acrylic-acid alkylester which has a C1-C20 linear or branched alkyl group. Adhesive sheet.   The said acrylic polymer (a) contains 2 mass% or more of structural units derived from a hydroxyl group-containing monomer, and contains 10 mass% or more of structural units derived from a heterocyclic ring-containing vinyl monomer. Adhesive sheet.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the acrylic polymer (a) includes a structural unit derived from a polyfunctional monomer having two or more polymerizable functional groups. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein the viscoelastic body layer (B) contains hollow particles. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5 , wherein the viscoelastic body layer (B) contains bubbles. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6 , wherein the viscoelastic body layer (B) contains an acrylic polymer (b) as a base polymer. The acrylic polymer (b) contains 50% by mass or more of a structural unit derived from a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms, and contains a carboxyl group The pressure-sensitive adhesive sheet according to claim 7 , comprising 5% by mass or more of a structural unit derived from a monomer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8 , wherein the pressure-sensitive adhesive layer (A) is provided on both front and back surfaces of the viscoelastic body layer (B).

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