JP2013253136A - Adhesive layer and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive layer exhibiting excellent adhesion to a non-polar adherend such as a polyethylene or a polypropylene, not deteriorating its characteristics even at low temperatures, and having excellent retentivity, terminal peelability and constant load peelability.SOLUTION: An adhesive layer is formed using a water-dispersed adhesive composition including: a (meth)acrylic polymer obtained by polymerizing a monomer component mainly composed of a (meth)acrylic acid alkyl ester having a 1-18C alkyl group; a latex containing a rubber component incompatible with the (meth)acrylic polymer and having a loss tangent peak temperature of -5°C or less as determined by dynamic viscoelasticity measurement with a shear strain at a frequency of 1 Hz; and a tackifier compatible with at least the rubber component. In the water-dispersed adhesive composition, a blending weight ratio of the (meth)acrylic polymer to the latex is from 95/5 to 40/60 in terms of solid content. A toluene-insoluble fraction of a phase formed of the acrylic polymer in the adhesive layer is 25-85%.

Description

  The present invention relates to an adhesive layer and an adhesive sheet having the adhesive layer.

  In recent years, from the viewpoint of environmental impact, it has been desired to reduce the use of organic solvents, and the pressure-sensitive adhesive composition that forms the pressure-sensitive adhesive layer laminated on the pressure-sensitive adhesive sheet is also a solvent type that uses an organic solvent as a solvent. Conversion from a pressure-sensitive adhesive composition to a water-dispersed pressure-sensitive adhesive composition that uses water as a dispersion medium has been attempted.

  As such an adhesive, an acrylic adhesive is widely used because of its versatility. However, acrylic pressure-sensitive adhesives generally have a problem of poor adhesion to nonpolar adherends such as polyethylene and polypropylene.

  In order to solve such a problem, an aqueous emulsion type adhesive composition for polyolefin to which a tackifying resin having a high softening point is added has been disclosed (for example, see Patent Document 1). In addition, an emulsion-type pressure-sensitive adhesive that contains an acrylic polymer and a rubber-based pressure-sensitive adhesive, and also exhibits good adhesion to a nonpolar adherend even at a low temperature by blending a rosin-based tackifier resin. It is disclosed (for example, see Patent Document 2).

Japanese Patent Publication No. 3-34786 JP 2008-163095 A

  Patent Documents 1 and 2 disclose that good adhesion can be provided to polyolefin-based adherends and the like, but this is not sufficient, and is higher than that for nonpolar adherends even at low temperatures. There is a need for an adhesive that can exhibit adhesive strength. Furthermore, there are also demands for retention when left at a constant temperature, end peelability, peelability when a constant load is applied (constant load peelability), and the like.

  Moreover, since the emulsion-type pressure-sensitive adhesive of Patent Document 2 uses a tackifier resin that is compatible only with an acrylic polymer, the elastic modulus of the rubber-based pressure-sensitive adhesive component cannot be lowered sufficiently, It is considered that a sufficient adhesive strength cannot be obtained. Moreover, when the tackifying resin is compatible with the acrylic polymer, the glass transition temperature (Tg) of the acrylic polymer is increased, and the elastic modulus of the acrylic polymer at a low temperature may be increased. This is considered to be one of the factors that a sufficient adhesive force cannot be obtained.

  The object of the present invention is excellent in adhesion to non-polar adherends such as polyethylene and polypropylene, and does not impair the characteristics even at low temperatures, and further retains when left at a certain temperature, and peels off the ends. It is to provide a pressure-sensitive adhesive layer excellent in constant load peelability and the like.

  The present inventor has intensively studied to solve the above problems. As a result, a (meth) acrylic polymer, a latex containing a rubber component that is incompatible with the (meth) acrylic polymer and has a loss tangent peak temperature of −5 ° C. or less, and at least A water-dispersed pressure-sensitive adhesive composition containing a tackifier that is compatible with the rubber component and having a blending weight ratio of the (meth) acrylic polymer and the latex of 95/5 to 40/60 in solid content. A toluene layer insoluble in the phase composed of an acrylic polymer in the pressure-sensitive adhesive layer is 25 to 85%, and a toluene insoluble content in the pressure-sensitive adhesive layer is 15 to 60 %, It has excellent adhesion to non-polar adherends, does not impair its properties even at low temperatures, and retains when left at a certain temperature, terminal peelability, constant load peelability. Etc. This has led to the completion of the present invention.

That is, the present invention provides a (meth) acrylic polymer obtained by polymerizing a monomer component mainly composed of a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group,
Latex containing a rubber component that is incompatible with the (meth) acrylic polymer and has a loss tangent peak temperature of −5 ° C. or lower, measured by dynamic viscoelasticity measurement at a shear strain of 1 Hz. When,
Containing at least a tackifier compatible with the rubber component,
The pressure-sensitive adhesive layer is formed using a water-dispersed pressure-sensitive adhesive composition in which the blending weight ratio of the (meth) acrylic polymer and the latex is 95/5 to 40/60 in terms of solid content,
It is related with the adhesive layer whose toluene insoluble content of the phase which consists of an acryl-type polymer in the said adhesive layer is 25 to 85%, and the toluene insoluble content of the said adhesive layer is 15 to 60%.

  The softening point of the tackifier is 80 to 160 ° C., and the compounding amount of the tackifier is 5 to 100 parts by weight with respect to a total of 100 parts by weight of the (meth) acrylic polymer and the rubber component. Preferably there is.

  It is preferable that the monomer component which has the said (meth) acrylic-acid alkylester as a main component contains a reactive functional group containing monomer.

  It is preferable that the reactive functional group-containing monomer is an alkoxysilyl group-containing vinyl monomer.

  It is preferable that the water-dispersed pressure-sensitive adhesive composition contains a crosslinking agent that reacts with the reactive functional group-containing monomer.

  The rubber component contained in the latex is preferably at least one selected from the group consisting of natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, and styrene butadiene rubber.

  Furthermore, this invention relates to the adhesive sheet which has the said adhesive layer.

  According to the present invention, the pressure-sensitive adhesive layer is excellent in adhesion to nonpolar adherends such as polyethylene and polypropylene, and has excellent retainability, terminal peelability, and constant load peelability without impairing properties even at low temperatures. Can be provided.

6 is a graph showing the results of confirming the compatibility between the (meth) acrylic polymer used in Example 7 and a rubber component. It is a figure which shows the TEM image of the adhesive sheet obtained in Example 7. FIG. It is sectional drawing which shows typically schematic structure of the adhesive sheet which concerns on this Embodiment.

Hereinafter, the present invention will be specifically described.
In the present specification, “A to B” indicating a range means that the range is A or more and B or less, and various physical properties mentioned in the present specification are in Examples described later unless otherwise specified. The value measured by the described method is meant. In the present specification, “(meth) acryl” in “(meth) acrylic polymer” and the like means “acryl and / or methacryl”. Furthermore, “water-dispersed” in the present specification means a form in which at least a part of the components are dispersed in water. For example, “water-dispersed pressure-sensitive adhesive composition” means a pressure-sensitive adhesive composition. It means that a part of the pressure-sensitive adhesive composition contains water and water and is partly dispersed in water. The “dispersed” means a state in which at least a part of the components are not dissolved in water, and includes a suspended state and an emulsified state.

(I) Water-dispersed pressure-sensitive adhesive composition The water-dispersed pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer of the present invention is mainly composed of (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group. The (meth) acrylic polymer obtained by polymerizing the monomer components, incompatible with the (meth) acrylic polymer, and measured by dynamic viscoelasticity measurement at a shear strain of 1 Hz. Further, it contains a latex containing a rubber component having a peak loss tangent temperature of −5 ° C. or less and a tackifier that is at least compatible with the rubber component.

  In the water-dispersed pressure-sensitive adhesive composition, since the (meth) acrylic polymer and the rubber component are incompatible, when the pressure-sensitive adhesive layer is formed, the (meth) acrylic polymer is used in the pressure-sensitive adhesive layer. It is considered that an acrylic phase mainly composed and a rubber phase mainly composed of a rubber component form a sea-island structure. As a result, it is considered that an acrylic phase and a rubber phase exist on the surface of the pressure-sensitive adhesive layer. The acrylic phase ensures adhesion to a polar adherend such as SUS, and the rubber phase is nonpolar such as polypropylene (PP). It is thought to provide adhesion to the adherend and low temperature adhesion.

  Hereinafter, each component will be described.

(I) (Meth) acrylic polymer The (meth) acrylic polymer is obtained by polymerizing a monomer component whose main component is a (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group. Can be obtained. The monomer component is not particularly limited as long as it has the (meth) acrylic acid alkyl ester as a main component. For example, if desired, a reactive functional group may be used. A contained unsaturated monomer, an unsaturated monomer copolymerizable with the (meth) acrylic acid alkyl ester or the functional group-containing unsaturated monomer, and the like may be appropriately contained. In addition, a main component is 60 weight% or more in all the monomers of a monomer component here.

As said (meth) acrylic-acid alkylester whose carbon number of an alkyl group is 1-18, the compound represented by following General formula (1) is mentioned.
(In general formula (1), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a linear or branched alkyl group having 1 to 18 carbon atoms.)

Specific examples of R ² in the general formula (1) include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, t-butyl group, pentyl group, neopentyl group, Isoamyl group, hexyl group, heptyl group, octyl group, 2-ethylhexyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, A hexadecyl group, a heptadecyl group, an octadecyl group, etc. are mentioned.

  Specific examples of the (meth) acrylic acid alkyl ester represented by the general formula (1) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid. Isopropyl, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, neopentyl (meth) acrylate, (meth ) Isoamyl acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) acrylic acid Nonyl, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate Undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, Examples include (meth) acrylate octadecyl. These alkyl (meth) acrylates may be used alone or in combination of two or more.

  As for carbon number of the alkyl group in the said (meth) acrylic-acid alkylester, it is more preferable that it is 2-18, and it is further more preferable that it is 4-12.

  The blending amount of the alkyl group having 1 to 18 carbon atoms in the alkyl group described above is preferably 60 parts by weight or more with respect to 100 parts by weight of the total amount of the monomer components. It is more preferably ˜99.5 parts by weight, and even more preferably 70 to 99 parts by weight.

  Moreover, the monomer component can contain a reactive functional group-containing monomer having a reactive functional group in the molecule in addition to the above-described (meth) acrylic acid alkyl ester. By including a reactive functional group-containing monomer, a cross-linked structure can be formed, and a pressure-sensitive adhesive having excellent retention, terminal peelability, and constant load peelability can be formed, which is preferable.

  The reactive functional group means a functional group that can react with a crosslinking agent to form a covalent bond and / or a coordinate bond with the crosslinking agent. Specifically as the reactive functional group, for example, carboxyl group, hydroxyl group, epoxy group, amino group, amide group, maleimide group, itaconimide group, succinimide group, sulfonic acid group, phosphoric acid group, isocyanate group, alkoxy group, An alkoxysilyl group etc. are mentioned. Such reactive functional groups may contain only 1 type, and may contain 2 or more types. Among the reactive functional groups, a carboxyl group, a hydroxyl group, an amino group, and an epoxy group are preferable.

  Specific examples of the reactive functional group-containing monomer include unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, croton, cinnamic acid; monomethyl itaconate, monobutyl itaconate Unsaturated dicarboxylic acid monoesters such as 2-acryloyloxyethylphthalic acid; Unsaturated tricarboxylic acid monoesters such as 2-methacryloyloxyethyl trimellitic acid and 2-methacryloyloxyethyl pyromellitic acid; Carboxyethyl acrylate (β-carboxyl Ethyl acrylate, etc.), carboxyalkyl acrylates such as carboxypentyl acrylate; acrylic acid dimer (trade name “Aronix M-5600”, manufactured by Toagosei Co., Ltd.), acrylic acid trimer; itaconic anhydride, maleic anhydride, anhydrous No fumaric acid Carboxyl group-containing unsaturated monomers such as Japanese dicarboxylic acid anhydrides; hydroxyl group-containing unsaturated monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate; (meth) acrylic Epoxy group-containing unsaturated monomers such as glycidyl acid and methyl glycidyl (meth) acrylate; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and t-butyl (meth) acrylate Amino group-containing unsaturated monomers such as aminoethyl; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl ( (Meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylo Amide group-containing unsaturated monomers such as propane (meth) acrylamide; Cyano group-containing unsaturated monomers such as (meth) acrylonitrile; N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide Maleimide group-containing monomers such as N-methyl itaconimide, N-ethyl itaconimide, N-butyl itaconimide, N-octyl itaconimide, N-2-ethylhexylitaconimide, N-cyclohexyl leuconconimide, N-lauryl Itaconimide group-containing monomers such as itaconimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide, etc. The Synimide group-containing monomer: N-vinylpyrrolidone, N- (1-methylvinyl) pyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole , N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, vinyl group-containing heterocyclic compounds such as (meth) acryloylmorpholine; styrenesulfonic acid, allylsulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfone Sulfonic acid group-containing unsaturated monomers such as acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid; phosphoric acid group containing such as 2-hydroxyethyl acryloyl phosphate Unsaturated monomer; 2-methacryloyl And functional monomers such as ruoxyethyl isocyanate. These may be used alone or in combination of two or more.

  The content ratio of the reactive functional group-containing monomer in the monomer component is preferably more than 0 parts by weight and 40 parts by weight or less with respect to 100 parts by weight of the total amount of monomer components. More preferably, it is 5-30 weight part, and it is further more preferable that it is 1-20 weight part. By containing the reactive functional group-containing monomer in an amount within the above range, when a crosslinking agent having crosslinking reactivity with respect to the functional group is used, the resulting acrylic polymer and crosslinking agent are Since a crosslinked structure can be formed satisfactorily and an adhesive having excellent retainability, terminal peelability, constant load peelability and the like can be formed, it is preferable.

  Moreover, as a reactive functional group containing monomer, an alkoxy silyl group containing vinyl monomer other than the above-mentioned thing can be mentioned. Examples of the alkoxysilyl group-containing vinyl monomer include silicone (meth) acrylate monomers and silicone vinyl monomers.

  Examples of the silicone-based (meth) acrylate monomer include (meth) acryloyloxymethyl-trimethoxysilane, (meth) acryloyloxymethyl-triethoxysilane, 2- (meth) acryloyloxyethyl-trimethoxysilane, 2- ( (Meth) acryloyloxyethyl-triethoxysilane, 3- (meth) acryloyloxypropyl-trimethoxysilane, 3- (meth) acryloyloxypropyl-triethoxysilane, 3- (meth) acryloyloxypropyl-tripropoxysilane, 3 -(Meth) acryloyloxypropyl-trialkoxysilane, (meth) acryloyloxyalkyl-trialkoxysilane such as 3- (meth) acryloyloxypropyl-tributoxysilane, for example (meth) Acryloyloxymethyl-methyldimethoxysilane, (meth) acryloyloxymethyl-methyldiethoxysilane, 2- (meth) acryloyloxyethyl-methyldimethoxysilane, 2- (meth) acryloyloxyethyl-methyldiethoxysilane, 3- (Meth) acryloyloxypropyl-methyldimethoxysilane, 3- (meth) acryloyloxypropyl-methyldiethoxysilane, 3- (meth) acryloyloxypropyl-methyldipropoxysilane, 3- (meth) acryloyloxypropyl-methyldi Isopropoxysilane, 3- (meth) acryloyloxypropyl-methyldibutoxysilane, 3- (meth) acryloyloxypropyl-ethyldimethoxysilane, 3- (meth) acryloyloxypropyl-e Rudiethoxysilane, 3- (meth) acryloyloxypropyl-ethyldipropoxysilane, 3- (meth) acryloyloxypropyl-ethyldiisopropoxysilane, 3- (meth) acryloyloxypropyl-ethyldibutoxysilane, 3- ( (Meth) acryloyloxypropyl-propyldimethoxysilane, (meth) acryloyloxyalkyl-alkyldialkoxysilane such as 3- (meth) acryloyloxypropyl-propyldiethoxysilane, and (meth) acryloyloxyalkyl-dialkyl corresponding to these (Mono) alkoxysilane etc. are mentioned.

  Examples of silicone vinyl monomers include vinyltrialkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, and vinyl corresponding to these. Alkyldialkoxysilanes and vinyldialkylalkoxysilanes such as vinylmethyltrimethoxysilane, vinylmethyltriethoxysilane, β-vinylethyltrimethoxysilane, β-vinylethyltriethoxysilane, γ-vinylpropyltrimethoxysilane, γ -Vinylalkyltriethoxysilane, γ-vinylpropyltripropoxysilane, γ-vinylpropyltriisopropoxysilane, γ-vinylpropyltributoxysilane, etc. Other alkoxysilane, these correspond and (vinyl) alkyl dialkoxy silanes include (vinyl alkyl) dialkyl (mono) alkoxysilanes.

  By using an alkoxysilyl group-containing vinyl monomer, an alkoxysilyl group is introduced into the polymer chain, and a crosslinked structure can be formed by a reaction between the silyl groups. These alkoxysilyl group-containing vinyl monomers are suitably used alone or in combination.

  The mixing ratio of these alkoxysilyl group-containing vinyl monomers is preferably, for example, 0 to 40 parts by weight, and more than 0 parts by weight and 40 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic acid alkyl ester. More preferably, it is more than 0 parts by weight and more preferably 30 parts by weight or less, more preferably more than 0 parts by weight and 10 parts by weight or less, more preferably more than 0 parts by weight and not more than 5 parts by weight. It is particularly preferred.

  Examples of the unsaturated monomer copolymerizable with the (meth) acrylic acid alkyl ester or the functional group-containing unsaturated monomer include vinyl ester group-containing monomers such as vinyl acetate; styrene, vinyl toluene, and the like. Aromatic unsaturated monomers: (meth) acrylic acid alicyclic hydrocarbon monomers such as cyclopentyl di (meth) acrylate and isobornyl (meth) acrylate; methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, etc. Alkoxy group-containing unsaturated monomers; ethylene, propylene, isoprene, butadiene, isobutylene and other olefin monomers; vinyl ether and other vinyl ether monomers; vinyl chloride and other halogen atom-containing unsaturated monomers; and other, for example, (meth) acrylic acid Tetrahydrofurfuryl , Fluorine (meth) or a heterocyclic ring such as acrylates, acrylic ester monomers containing a halogen atom.

  The monomer component may further contain a polyfunctional monomer. Examples of the multifunctional monomer include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and tetraethylene glycol di (meth) acrylate. (Mono or poly) ethylene glycol di (meth) acrylate such as; (mono or poly) alkylene glycol di (meth) acrylate such as (mono or poly) propylene glycol di (meth) acrylate such as propylene glycol di (meth) acrylate ; Neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, tetramethylol methanetri (meth) acrylate, pentaerythritol di (meth) acrylate (Meth) acrylic acid ester of polyhydric alcohols such as rate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate; divinylbenzene and the like. Moreover, epoxy acrylate, polyester acrylate, urethane acrylate, etc. are mentioned as a polyfunctional monomer.

  The blending ratio of the copolymerizable unsaturated monomer and the polyfunctional monomer is not particularly limited. For example, 10 parts by weight with respect to 100 parts by weight of the total amount of the monomer components. The amount is preferably 5 or less and more preferably 5 parts by weight or less.

  The (meth) acrylic polymer according to the present invention is obtained by polymerizing the above-described monomer component by a polymerization method such as emulsion polymerization.

  In emulsion polymerization, for example, a polymerization initiator, an emulsifier, and, if necessary, a chain transfer agent and the like are appropriately mixed and polymerized together with the above-described monomer components. More specifically, for example, known emulsion polymerization methods such as a batch charging method (batch polymerization method), a monomer dropping method, a monomer emulsion dropping method, and the like can be employed. In the monomer dropping method, continuous dropping or divided dropping is appropriately selected. Although reaction conditions etc. are selected suitably, superposition | polymerization temperature is 20-100 degreeC, for example.

  The polymerization initiator is not particularly limited, and a polymerization initiator usually used for emulsion polymerization is used. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2, 2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate, 2,2′-azobis (N, N Azo initiators such as' -dimethyleneisobutylamidine), 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, for example, persulfate such as potassium persulfate and ammonium persulfate Salt initiators, for example, peroxide initiators such as benzoyl peroxide, t-butyl hydroperoxide, hydrogen peroxide, for example, substituted ethane initiators such as phenyl substituted ethane, Eg to a carbonyl-based initiators such as aromatic carbonyl compounds, for example, a combination of a persulfate and sodium hydrogen sulfite, redox initiators such as a combination of a peroxide and sodium ascorbate and the like.

  These polymerization initiators are suitably used alone or in combination. The blending ratio of the polymerization initiator is appropriately selected, but is preferably 0.005 to 1 part by weight, for example, based on 100 parts by weight of the total amount of the monomer components, and 0.01 to 0 More preferably, it is 8 parts by weight.

  The emulsifier is not particularly limited, and an emulsifier usually used for emulsion polymerization is used. For example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene Anionic emulsifiers such as sodium alkylsulfosuccinate; nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene polyoxypropylene block polymer, and the like. In addition, radically polymerizable (reactive) emulsifiers (for example, HS-10 (No. 1), in which radically polymerizable functional groups (reactive groups) such as propenyl groups and allyl ether groups are introduced into these anionic and nonionic emulsifiers. Ichikogaku Pharmaceutical Co., Ltd.)) may be used.

  These emulsifiers are used alone or in combination as appropriate. Moreover, the blending ratio of the emulsifier is preferably 0.2 to 10 parts by weight, and more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the total amount of the monomer components. .

  The chain transfer agent adjusts the molecular weight of the polymer as necessary, and a chain transfer agent usually used for emulsion polymerization is used. Examples thereof include mercaptans such as 1-dodecanethiol, t-dodecanethiol, mercaptoacetic acid, 2-mercaptoethanol, 2-ethylhexyl thioglycolate, and 2,3-dimethylcapto-1-propanol. These chain transfer agents are appropriately used alone or in combination. Moreover, the mixture ratio of a chain transfer agent is 0.001-0.5 weight part with respect to 100 weight part of total amounts of a monomer component, for example.

  For the purpose of improving the stability of the (meth) acrylic polymer, the pH may be adjusted to, for example, pH 7 to 9, preferably pH 7 to 8, for example, with ammonia water.

(Ii) Latex water-dispersed pressure-sensitive adhesive composition containing a rubber component is incompatible with the (meth) acrylic polymer, and measured by dynamic viscoelasticity measurement at a shear strain of 1 Hz. A latex containing a rubber component having a peak loss tangent temperature of −5 ° C. or lower (hereinafter sometimes referred to as “rubber-based latex”) is included, and the rubber component is applied to a nonpolar adherend. Excellent adhesion, low elastic modulus at low temperatures, and excellent wettability to adherends in low temperature environments.

  In addition, a dynamic viscoelasticity measurement can be performed by the method similar to "(8) Dynamic viscoelasticity measurement of an adhesive sheet" of the Example mentioned later in the shear strain of frequency 1Hz.

  The peak temperature of the loss tangent of the rubber component is −5 ° C. or lower, preferably −10 ° C. or lower, and more preferably −15 ° C. or lower. If the peak tangent temperature of the loss tangent of the rubber component is higher than this range, the elastic modulus at a low temperature increases, and the adhesive force tends to decrease. In other words, by setting the peak temperature of the loss tangent of the rubber component within the above range, the elastic modulus at low temperature can be lowered and the adhesive strength at low temperature can be improved. The lower limit of the loss tangent peak temperature of the rubber component is not particularly limited, but can be, for example, -130 ° C or higher, preferably -120 ° C or higher, more preferably -110 ° C or higher.

  Examples of the rubber latex include natural rubber latex and synthetic rubber latex. The natural rubber latex may be a modified natural rubber obtained by grafting (meth) acrylic acid alkyl ester or the like to natural rubber.

  Synthetic rubber latex is an aqueous dispersion of synthetic polymer. The types of synthetic polymers are polyisoprene, styrene-butadiene copolymer (SBR), styrene-butadiene-vinylpyridine polymer, and polybutadiene. Examples thereof include a polymer, a methyl methacrylate-butadiene copolymer, an acrylonitrile-butadiene polymer (NBR), and polychloroprene (CR).

  It should be noted that those skilled in the art can adjust the composition ratio (copolymerization ratio) of the rubber component based on the description of the present specification including specific examples to be described later and the common technical knowledge such as the sp value. Understand how to obtain a latex containing a rubber component that is incompatible with the (meth) acrylic polymer and the peak temperature of loss tangent is in the above-mentioned range by adjusting obtain.

  A commercially available rubber latex can be used. For example, as polyisoprene latex, manufactured by Sumitomo Seika Co., Ltd. (Sepolex IR-100K), as styrene-butadiene latex, manufactured by Nippon Zeon Co., Ltd. (Nipol series), manufactured by JSR Corporation, Asahi Kasei Latex. DIC Co., Ltd. (Luck Star Series), Japan A & L Co., Ltd. (Nal Star Series), and the like. Examples of styrene-butadiene-vinyl pyridine latex include ZEON CORPORATION. ) (Nipol series), Nippon A & L Co. (Pilatex series), etc., and polybutadiene latex includes Nihon Zeon (Nipol series), MMA Examples of polybutadiene latex include those manufactured by Nippon A & L Co., Ltd. (Nalsta Series), etc., and acrylonitrile-butane. Examples of the enlatex include Nippon Zeon Co., Ltd. (Nipol Series), Japan A & L Co., Ltd. (Siatex Series), DIC Corporation (Lux Star Series), and the like. Chloroprene Examples of latex include Showa Denko Co., Ltd. (Show Pren Series), Tosoh Co., Ltd. (Sky Pren Series), and the like.

  These rubber latexes may be any rubber latex as long as the rubber component is incompatible with the (meth) acrylic polymer.

  In the pressure-sensitive adhesive layer formed from the water-dispersed pressure-sensitive adhesive composition, the (meth) acrylic polymer exists in an incompatible state with the rubber component. The compatible state of the (meth) acrylic polymer component and the rubber component is the peak derived from the (meth) acrylic polymer component in the loss modulus curve and loss tangent curve obtained by dynamic viscoelasticity measurement. It can be confirmed by a peak derived from the rubber component. Specifically, for example, as shown in FIG. 1, in a loss elastic modulus (G ″) curve or loss tangent (tan δ) curve obtained by dynamic viscoelasticity measurement, a (meth) acrylic polymer component In the case of showing two peaks, the peak derived from the rubber component and the peak derived from the rubber component, this indicates that the (meth) acrylic polymer component and the rubber component are in an incompatible state.

  In the state where the rubber component of the rubber-based latex and the (meth) acrylic polymer are incompatible, the acrylic phase mainly composed of the (meth) acrylic polymer in the pressure-sensitive adhesive after drying. And a rubber phase mainly composed of a rubber component forms a sea-island structure. For example, as shown in FIG. 2, such a structure can visually confirm a section of the pressure-sensitive adhesive after drying using a transmission electron microscope (TEM).

  Therefore, in the loss modulus curve and loss tangent curve obtained by dynamic viscoelasticity measurement, if the peak derived from the (meth) acrylic polymer component and the peak derived from the rubber component overlap, the transmission type The compatibility is judged by determining whether or not a sea-island structure is formed by an electron microscope (TEM). In this case, in the present invention, as long as the sea-island structure is formed, even if there is a compatible region, it is determined that it is incompatible.

  The blending weight ratio of such (meth) acrylic polymer and rubber latex ((meth) acrylic polymer / rubber latex) is 95/5 to 40/60 in terms of solid content, and 90/10. ~ 50/50 is preferred. If the rubber component is less than the above-mentioned range, the adhesion to the nonpolar adherend and the adhesion at low temperature tend to be reduced. Moreover, when there are few acrylic polymer components than the above-mentioned range, there exists a tendency for sufficient adhesive force with respect to polar adherends, such as SUS, not to be acquired.

(Iii) Tackifier The water-dispersed pressure-sensitive adhesive composition contains at least a tackifier that is compatible with the rubber component. “At least” means that it is essential to be compatible with the rubber component, but it may or may not be compatible with the acrylic polymer.

  By including the tackifier, it is considered that the elastic modulus of the rubber phase is lowered in a wide temperature range including a low temperature, the wettability to the adherend is improved, and a better adhesive force can be obtained.

  Examples of such tackifiers include tackifier resins such as rosin resins such as rosin ester, hydrogenated rosin ester, disproportionated rosin ester, and polymerized rosin ester; coumarone indene resin and hydrogenated coumarone. Coumarone indene resins such as indene resin, phenol modified coumarone indene resin, epoxy modified coumarone indene resin; α-pinene resin, β-pinene resin; polyterpene resin, hydrogenated terpene resin, aromatic modified terpene resin, terpene phenol Examples thereof include terpene resins such as resins; petroleum resins such as aliphatic petroleum resins, aromatic petroleum resins, and aromatic modified aliphatic petroleum resins. These can be used alone or in combination of two or more, and rosin resins, terpene resins and coumarone indene resins are particularly preferable.

  It is considered that when the tackifier is compatible with the rubber component, the elastic modulus of the rubber phase is lowered, and as a result, the wettability to the adherend is improved and the adhesion is improved.

  The compatibility of the tackifier can be determined by the haze of the pressure-sensitive adhesive sheet after drying. Specifically, “(2) Confirmation of compatibility between rubber component and tackifier” and “(3) Confirmation of compatibility between (meth) acrylic polymer and tackifier” in Examples described later. It is judged based on the method.

  The compounding amount of the tackifier is preferably 5 to 100 parts by weight, for example, and 10 to 90 parts by weight with respect to a total of 100 parts by weight of the (meth) acrylic polymer and the rubber component. Is more preferable. Below the above-mentioned range, the elastic modulus of the rubber phase is not sufficiently lowered, and the wettability to the adherend tends to be insufficient. If the above range is exceeded, the glass transition temperature of the rubber phase rises and the elastic modulus at low temperatures rises, so that sufficient wettability to the adherend cannot be obtained at low temperatures and the adhesive strength tends to decrease. There is.

  The tackifier that is compatible with the rubber component preferably has a softening point of 80 to 160 ° C, and more preferably 90 to 150 ° C. If it is below the above range, the cohesive force of the pressure-sensitive adhesive tends to decrease, and if it exceeds the above range, the low-temperature adhesive force tends to decrease. In addition, the softening point of tackifying resin can be measured based on the ring and ball method (JIS K-5902), for example.

  Although the addition form of tackifying resin is not specifically limited, Usually, it is suitable to add in the form of the aqueous dispersion in which tackifying resin was previously disperse | distributed to water. As such an aqueous dispersion of tackifier resin, a commercially available one may be used, or a solution obtained by forcibly dispersing a desired tackifier resin in water using a disperser may be used.

  In the water-dispersed pressure-sensitive adhesive composition, a tackifier that is compatible only with the (meth) acrylic polymer may be used in combination with a tackifier that is compatible with at least the rubber-based component. By using such a pressure-sensitive adhesive in combination, there is an effect of further improving the adhesive strength at room temperature.

  Examples of tackifying resins that are compatible only with such (meth) acrylic polymers include rosin resins such as rosin esters, hydrogenated rosin esters, disproportionated rosin esters, and polymerized rosin esters; coumarone indene resins , Hydrogenated coumarone indene resin, phenol modified coumarone indene resin, coumarone indene resin such as epoxy modified coumarone indene resin; α-pinene resin, β-pinene resin; polyterpene resin, hydrogenated terpene resin, aromatic modified Examples include terpene resins such as terpene resins and terpene phenol resins; petroleum resins such as aliphatic petroleum resins, aromatic petroleum resins, and aromatic modified aliphatic petroleum resins, and rosin ester resins are particularly preferable. These may be used alone or in combination of two or more.

  In addition, as tackifier resins such as terpene and rosin, various tackifier resins having a wide sp value are available (see, for example, “Adhesion Handbook (Third Edition)” (published by Japan Adhesive Tape Industry Association)). Those skilled in the art will be able to provide a tackifying resin or (meth) acrylic polymer that is compatible with the rubber component based on the description in the present specification including specific examples described later, and technical common knowledge such as sp value. It is possible to understand how to obtain a tackifier resin that is compatible only with the above.

  The blending amount of the tackifying resin that is compatible only with the (meth) acrylic polymer is, for example, 0 to 20 parts by weight with respect to a total of 100 parts by weight of the (meth) acrylic polymer and the rubber component. The amount is preferably more than 0 parts by weight and more preferably 20 parts by weight or less, and still more preferably 1 to 10 parts by weight. If the above range is exceeded, the glass transition temperature of the acrylic phase mainly composed of (meth) acrylic polymers will rise, and the elastic modulus at low temperatures will rise. May not be sufficiently obtained and adhesive strength may be reduced.

  In addition, the water-dispersed pressure-sensitive adhesive composition may be used in combination with the above-described tackifier and use a liquid tackifier resin at room temperature.

  The addition form of the tackifying resin that is liquid at room temperature is not particularly limited, but it is preferable that the tackifying resin that is liquid at room temperature is added in a dispersion in which water is dispersed in advance. As such an aqueous dispersion of a tackifying resin that is liquid at room temperature, a commercially available one may be used, or a solution obtained by forcibly dispersing a desired tackifying resin in water using a disperser. May be. The tackifying resin that is liquid at room temperature refers to a resin having a softening point of 25 ° C. or lower before being dispersed as an emulsion. In the present invention, among these resins, a low molecular weight polymer of rosin ester and / or terpene is particularly preferable.

  The tackifier resin that is liquid at room temperature is preferably compatible with the rubber component. When the liquid tackifying resin is compatible with the rubber component at room temperature, the elastic modulus of the rubber phase is lowered, and the wettability to the adherend is improved, thereby improving the adhesive force.

  The blending amount of the tackifying resin that is liquid at room temperature is preferably, for example, 0 to 50 parts by weight with respect to 100 parts by weight in total of the (meth) acrylic polymer and the rubber component, and from 0 parts by weight. It is more preferably 50 parts by weight or less, and further preferably 1 to 40 parts by weight. When the above range is exceeded, the cohesive strength of the pressure-sensitive adhesive tends to decrease.

(Iv) Crosslinking agent The water-dispersed pressure-sensitive adhesive composition preferably contains a crosslinking agent that reacts with the reactive functional group. The crosslinking agent is not particularly limited as long as it is a compound containing two or more functional groups that react with the reactive functional group. For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent. Agents, metal chelate crosslinking agents, carbodiimide crosslinking agents, and the like. These crosslinking agents are not particularly limited, and oil-soluble or water-soluble crosslinking agents are used.

  When using an epoxy-based crosslinking agent, for example, a crosslinked structure is formed by incorporating a hydroxyl group such as a carboxyl group or a phenolic hydroxyl group, an amino group, an acid anhydride group, or the like as a reactive functional group in an acrylic polymer. be able to.

  The epoxy-based crosslinking agent is not particularly limited. For example, bisphenol A epichlorohydrin type epoxy resin, ethylene diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol Diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N′-diamine) Examples thereof include compounds having two or more epoxy groups in a molecule such as glycidylaminomethyl) cyclohexane.

  Among these, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine and 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane have good reactivity and well-balanced crosslinking. Since a structure can be formed, it is preferably used.

  In the case of using an isocyanate-based crosslinking agent, for example, a crosslinked structure can be formed by incorporating a hydroxyl group, an amino group, a carboxyl group or the like as a reactive functional group in an acrylic polymer.

  The isocyanate group-containing compound is not particularly limited, and examples thereof include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), and trimethylhexamethylene diisocyanate (TMDI). Xylene diisocyanate (XDI), naphthalene diisocyanate (NDI), trimethylolpropane (TMP) adduct TDI, TMP adduct IPDI, and the like.

  When using the said isocyanate type crosslinking agent, in order to promote a crosslinking reaction, you may use a catalyst. As such a catalyst, an amine catalyst or an organometallic catalyst is generally used. For example, N, N-dimethylcyclohexylamine, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, N′-tetra Amine catalysts such as methylethylenediamine, bis-2-dimethylaminoether, triethylenediamine, triethanolamine, stannous octoate, stannous oleate, dibutyltin diacetate, dibutyltin dilaurate, dimethyltin mercaptide, dimethyltin Examples thereof include organometallic catalysts such as dimaleate and lead octoate.

  The said catalyst may be used individually by 1 type, may be used in combination of 2 or more type, and is normally used by 0.001-5.0 weight part with respect to 100 weight part of crosslinking agents.

  When using an oxazoline-based crosslinking agent, for example, a carboxyl group, a hydroxyl group, an aromatic mercapto group, an acid anhydride, or the like as a reactive functional group can be included in the acrylic polymer to form a crosslinked structure.

  Although it does not specifically limit as an oxazoline type crosslinking agent, For example, the crosslinking agent illustrated by Unexamined-Japanese-Patent No. 2009-001673 is mentioned, Specifically, the main chain which consists of an acrylic skeleton or a styrene skeleton is included, The main Examples include compounds having an oxazoline group in the side chain of the chain, preferably an oxazoline group-containing acrylic polymer containing a main chain composed of an acrylic skeleton and having an oxazoline group in the side chain of the main chain Is mentioned.

  In the case of using an aziridine-based crosslinking agent, for example, a crosslinked structure can be formed by including, as a reactive functional group, a carboxyl group, a glycidyl group, an isocyanate group, or the like in an acrylic polymer.

  Although it does not specifically limit as an aziridine type crosslinking agent, For example, a trimethylol propane tris [3- (1-aziridinyl) propionate], a trimethylol propane tris [3- (1- (2-methyl) aziridinyl propionate)] ].

  In the case of using a metal chelate crosslinking agent, for example, a crosslinked structure can be formed by including, as a reactive functional group, a carboxyl group, a hydroxyl group, a glycidyl group, an isocyanate group, or the like in an acrylic polymer.

  Although it does not specifically limit as a metal chelate type crosslinking agent, For example, the crosslinking agent illustrated by Unexamined-Japanese-Patent No. 2007-063536 is mentioned, Specifically, for example, an aluminum chelate type compound, a titanium chelate type compound, zinc Examples include chelate compounds, zirconium chelate compounds, iron chelate compounds, cobalt chelate compounds, nickel chelate compounds, tin chelate compounds, manganese chelate compounds, and chromium chelate compounds.

  In the case of using a carbodiimide-based crosslinking agent, for example, a carboxyl group, an amino group, a hydroxyl group or the like as a reactive functional group can be included in the acrylic polymer to form a crosslinked structure.

Any carbodiimide-based crosslinking agent may be used as long as it contains at least two carbodiimide groups in the molecule. In addition, a carbodiimide group shows the group (-N = C = NH, -N = C = N-) by which one or two hydrogen atoms were extracted from carbodiimide (HN = C = NH). For ^{example, R 3 -N = C = N} -R 4 -N = C = N-R 5 (R 3, R 4, R 5 denotes a both hydrocarbon group.) Represented by the compound, and the like .

Moreover, as a carbodiimide type crosslinking agent, the polymer (polycarbodiimide) etc. which have a carbodiimide group can be used conveniently. In addition to the carbodiimide group, a polymer having a portion excellent in affinity with water, such as an ethylene oxide (—CH ₂ —CH ₂ —O—) portion, can be used particularly preferably. Examples of commercially available polymers having a carbodiimide group (polycarbodiimide) that can be used as a carbodiimide-based crosslinking agent include, for example, Nisshinbo Co., Ltd., trade names “Carbodilite V-02”, “Carbodilite V-02-L2”, “Carbodilite V-04”, “Carbodilite E-01”, “Carbodilite E-02” and the like.

  In the water-dispersed pressure-sensitive adhesive composition, the amount of the crosslinking agent used may be appropriately changed depending on the type of the crosslinking agent used, but is usually 0.0007 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer. Preferably, 0.001 to 5 parts by weight is more preferable. By using the cross-linking agent within the above range, a pressure-sensitive adhesive layer excellent in retention, terminal peelability, and constant load peelability can be formed.

(V) Other components In the water-dispersed pressure-sensitive adhesive composition, a viscosity modifier, a release modifier, a plasticizer, a softener, a filler, a colorant (pigment, dye, etc.), an anti-aging agent, Additives that are usually added to pressure-sensitive adhesives such as surfactants, leveling agents and antifoaming agents may be further added. The blending ratio of these additives is not particularly limited and can be appropriately selected. For example, it is preferable to contain 5 parts by weight or less with respect to 100 parts by weight of the solid content of the water-dispersed pressure-sensitive adhesive composition. .

  Examples of the viscosity modifier include acrylic alkali thickening type, urethane type association type, clay type, cellulose type, and polyamide type. For example, it may be blended at 1% by weight or less in the water-dispersed pressure-sensitive adhesive composition. Can be blended at 0.01 to 1% by weight. By using a viscosity modifier in such a range, it can be adjusted to the viscosity which can apply a water-dispersed adhesive composition, and an adhesive sheet without a repellency and a stripe can be obtained.

  The water-dispersed pressure-sensitive adhesive composition has a storage elastic modulus at -15 ° C. to 25 ° C. of 1 MPa or less measured by dynamic viscoelasticity measurement at a shear strain of 1 Hz when the pressure-sensitive adhesive is formed. Preferably, it is 0.9 MPa or less. If it is higher than the above range, the wettability to the adherend is not sufficient, and thus the adhesiveness tends to decrease. Moreover, although it does not specifically limit about a minimum, For example, it can be 0.01 Mpa or more.

(II) Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer of the present invention is formed using the water-dispersed pressure-sensitive adhesive composition. The forming method is not particularly limited, and a known method can be adopted, but it can be performed according to the following method for producing a pressure-sensitive adhesive sheet.

  Moreover, the toluene insoluble part (gel fraction) of the adhesive layer of this invention is 15 to 60%, and it is preferable that it is 20 to 55%. The gel fraction of the pressure-sensitive adhesive is measured by the method described in Examples described later.

  The toluene insoluble content (gel fraction) of the rubber latex forming the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 95% or less, more preferably 90% or less. The gel fraction of rubber latex is measured by the method described in the examples described later.

When the crosslinking agent forms a crosslinked structure with the (meth) acrylic polymer having a reactive functional group in the water-dispersed pressure-sensitive adhesive composition of the present invention, but does not crosslink with the rubber component, the pressure-sensitive adhesive gel From the fraction and the gel fraction of the rubber latex, the gel fraction of the acrylic phase composed of the (meth) acrylic polymer in the pressure-sensitive adhesive layer can be determined as follows.

  Thus, the gel fraction of the acrylic phase which consists of an acryl-type polymer obtained is 25-85%, and it is preferable that it is 30-80%. When the gel fraction of the acrylic phase is lower than the above range, sufficient cohesive force cannot be obtained, and when it is higher than the above range, the elastic modulus of the acrylic component becomes too high and the wettability to the adherend is lowered, and sufficient Adhesive strength cannot be obtained, and terminal peelability and constant load peelability also deteriorate.

(III) Adhesive sheet The adhesive sheet which concerns on this invention has the said adhesive layer.

  The pressure-sensitive adhesive sheet according to the present invention may be a pressure-sensitive adhesive sheet with a substrate having such a pressure-sensitive adhesive layer on one side or both sides of a sheet-like base material (support), and the pressure-sensitive adhesive layer is a release sheet (release surface). It may be a sheet-like base material provided with a base material-less pressure-sensitive adhesive sheet such as a form held on the base material. The concept of the pressure-sensitive adhesive sheet herein may include what are called pressure-sensitive adhesive tapes, pressure-sensitive adhesive labels, pressure-sensitive adhesive films and the like.

  The pressure-sensitive adhesive layer is typically formed continuously, but is not limited to such a form. For example, the pressure-sensitive adhesive layer is formed in a regular or random pattern such as a spot or stripe. It may be a layer. The pressure-sensitive adhesive sheet provided by the present invention may be in the form of a roll or a single sheet. Or the adhesive sheet of the form processed into various shapes may be sufficient.

  The pressure-sensitive adhesive sheet according to the present invention can have, for example, a cross-sectional structure schematically shown in FIGS.

  FIG. 3A is a configuration example of a single-sided pressure-sensitive adhesive sheet with a base material, and a pressure-sensitive adhesive layer 2 is provided on one side of the base material 1. Such a pressure-sensitive adhesive sheet has, for example, a pressure-sensitive adhesive layer 2 as shown in FIG. It can form in a roll shape by winding so that the peeling surface of the base material 1 currently laminated | stacked may contact the adhesive layer 2 laminated | stacked on the base material 1. FIG.

  In the pressure-sensitive adhesive sheet shown in FIG. 3B, the pressure-sensitive adhesive layer 2 has a configuration protected by a release sheet 3 having at least the pressure-sensitive adhesive layer side as a release surface, and rolls when wound. It can also be formed.

  In the pressure-sensitive adhesive sheet shown in FIG. 3 (c), the pressure-sensitive adhesive layer 2 is provided on both surfaces of the substrate 1, and both of the pressure-sensitive adhesive layers 2 are release sheets 3 in which at least the pressure-sensitive adhesive layer side is a release surface. Each has a protected structure. The pressure-sensitive adhesive sheet shown in FIG. 3C is, for example, formed in a roll shape by previously forming the pressure-sensitive adhesive layer 2 on the release sheet 3, pasting it on the front and back surfaces of the substrate 1, and winding it. Can be formed.

  In the pressure-sensitive adhesive sheet shown in FIG. 3C, the pressure-sensitive adhesive layer 2 is provided on both surfaces of the substrate 1, but these pressure-sensitive adhesive layers 2 may be formed of pressure-sensitive adhesives having the same composition or different. You may form with the adhesive of the composition which was different, respectively.

  Examples of the material for forming the base material include polyolefin films such as polyethylene, polypropylene, and ethylene / propylene copolymers; polyester films such as polyethylene terephthalate; plastic films such as polyvinyl chloride; paper such as kraft paper and Japanese paper Kinds: Cloths such as cotton cloth and soft cloth; woven cloths such as polyester non-woven cloth and vinylon cloth woven cloth; metal foil.

  The plastic films may be non-stretched films or stretched (uniaxially stretched or biaxially stretched) films. The surface of the substrate on which the pressure-sensitive adhesive layer is provided may be subjected to a surface treatment such as application of a primer and corona discharge treatment.

  The pressure-sensitive adhesive layer is obtained by applying the above-mentioned water-dispersed pressure-sensitive adhesive composition to a substrate using a known coating method and drying it. The method for applying the water-dispersed pressure-sensitive adhesive composition to the substrate is not particularly limited. For example, a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, fountain die coater. Or a closed edge die coater.

  The pressure-sensitive adhesive layer may be formed by applying a water-dispersed pressure-sensitive adhesive composition to a release sheet to form a pressure-sensitive adhesive layer, and then transferring it to a substrate.

  The thickness in particular of the adhesive layer after drying is not restrict | limited, For example, it is preferable that it is 500 micrometers or less, and it is more preferable that it is 5-200 micrometers. Although drying temperature is based also on the kind of base material, it can be 40-120 degreeC, for example.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.

[Synthesis Example 1: Synthesis of water-dispersed (meth) acrylic polymer (A)]
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 96 parts of butyl acrylate (BA), 4 parts of acrylic acid (AA), 0.08 part of t-dodecanethiol (chain transfer agent), polyoxy An emulsion obtained by emulsifying 2 parts of sodium lauryl sulfate (emulsifier) and 153 parts of ion-exchanged water (that is, an emulsion of a monomer raw material) was charged and stirred for 1 hour while introducing nitrogen gas.

  Thereafter, the temperature was raised to 60 ° C. and 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (polymerization initiator) prepared in a 10% aqueous solution (trade name: VA). -057, manufactured by Wako Pure Chemical Industries, Ltd.) was added in an amount of 0.1 part as a solid content and polymerized for 3 hours. 10% ammonium water was added thereto to adjust the liquidity to pH 7.5 to obtain a water-dispersed (meth) acrylic polymer (A).

[Synthesis Example 2: Synthesis of water-dispersed (meth) acrylic polymer (B)]
2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (polymerization initiator) (commercial initiator) in a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer Name: VA-057, manufactured by Wako Pure Chemical Industries, Ltd. (0.1 part) and ion-exchanged water (40 parts) were added and stirred for 1 hour while introducing nitrogen gas. This was kept at 60 ° C., and 70 parts of butyl acrylate, 30 parts of 2-ethylhexyl acrylate, 3 parts of acrylic acid, 3-methacryloyloxypropyltrimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) Emulsified by adding 0.03 part, 0.05 part of t-dodecanethiol (chain transfer agent) and 2 parts of polyoxyethylene lauryl sodium sulfate (emulsifier) to 30 parts of ion-exchanged water (that is, an emulsion of a monomer raw material) ) Was added dropwise over 3 hours, and after completion of the dropwise addition, the mixture was further polymerized at the same temperature for 3 hours. 10% ammonium water was added thereto to adjust the liquidity to pH 7.5, and a water-dispersed (meth) acrylic polymer (B) was obtained.

[Synthesis Example 3: Synthesis of water-dispersed (meth) acrylic polymer (C)]
2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (polymerization initiator) (commercial initiator) in a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer Name: VA-057, manufactured by Wako Pure Chemical Industries, Ltd. (0.1 part) and ion-exchanged water (40 parts) were added and stirred for 1 hour while introducing nitrogen gas. This was kept at 60 ° C., and 85 parts of 2-ethylhexyl acrylate, 13 parts of methyl acrylate, 1.25 parts of acrylic acid, 1.25 parts of methacrylic acid (MAA), 3-methacryloyloxypropyltrimethoxysilane (trade name: KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.02 part, t-dodecanethiol (chain transfer agent) 0.048 part and sodium polyoxyethylene lauryl sulfate (emulsifier) 2 parts are added to 30 parts of ion-exchanged water. Then, the emulsified product (that is, the monomer raw material emulsion) was added dropwise over 3 hours, and after completion of the addition, the mixture was further polymerized at the same temperature for 3 hours. 10% ammonium water was added thereto to adjust the liquidity to pH 7.5, and a water-dispersed (meth) acrylic polymer (C) was obtained.

[Example 1]
70 parts by weight of the water-dispersed (meth) acrylic polymer (A) obtained in Synthesis Example 1 and a synthetic polyisoprene latex (trade name “Sepolex IR-100K”, manufactured by Sumitomo Seika Co., Ltd.) 30 parts in a solid content. Next, 18 parts of an aromatic modified terpene resin emulsion (trade name “Nanolet R-1050”, manufactured by Yasuhara Chemical Co., Ltd., softening point 100 ° C.) as a tackifier is blended in solid content, and an epoxy-based crosslinking agent (trade name) 0.04 part of “TETRAD-C” (Mitsubishi Gas Chemical Co., Ltd.) was blended to prepare a water-dispersed pressure-sensitive adhesive composition.

  Subsequently, the prepared water-dispersed pressure-sensitive adhesive composition was mixed with 0.5 part of an acrylic alkali thickening type thickener (trade name “Aron B-500”, manufactured by Toa Gosei Co., Ltd.) to increase the viscosity. The thickened water-dispersed pressure-sensitive adhesive composition is coated on a polyethylene terephthalate substrate (trade name “Lumirror S-10”, manufactured by Toray Industries, Inc.) having a thickness of 25 μm so that the thickness after drying becomes 60 μm. And this was dried at 100 degreeC for 3 minute (s), and the adhesive sheet was produced.

[Examples 2 to 9]
Except having set it as the composition shown in Table 1, operation similar to Example 1 was performed and the adhesive sheet was produced.

Example 10
The water-dispersed (meth) acrylic polymer (A) obtained in Synthesis Example 1 is changed to the water-dispersed (meth) acrylic polymer (B) obtained in Synthetic Example 2, and an epoxy crosslinking agent is used. Except not having performed, operation similar to Example 1 was performed and the adhesive sheet was produced.

Example 11
The water-dispersed (meth) acrylic polymer (A) obtained in Synthesis Example 1 is changed to the water-dispersed (meth) acrylic polymer (C) obtained in Synthetic Example 3, and an epoxy crosslinking agent is used. Except not having performed, operation similar to Example 1 was performed and the adhesive sheet was produced.

Example 12
Synthetic polyisoprene latex is made into synthetic polybutadiene latex (trade name “Nipol LX-111K”, manufactured by Nippon Zeon Co., Ltd.), and aromatic modified terpene resin emulsion (trade name “Nanolet R-1050”, Yashara Chemical Co., Ltd.) as a tackifier. Manufactured, softening point 100 ° C.) is added to 18 parts by solid content, and rosin-based tackifier (trade name “Tamanol E-200NT”, Arakawa Chemical Industries, softening point 145 ° C.) is added 12 parts by solid content. Except for further blending, the same operation as in Example 11 was performed to prepare an adhesive sheet.

[Comparative Example 1]
100 parts of the water-dispersed (meth) acrylic polymer (A) obtained in Synthesis Example 1 was added to an acrylic alkaline thickening agent (trade name “Aron B-500”, manufactured by Toa Gosei Co., Ltd.) 0 The mixture was thickened by mixing with 5 parts, and the thickened water-dispersed pressure-sensitive adhesive composition was added to a 25 μm polyethylene terephthalate substrate (trade name “Lumirror S-10”, Toray Industries, Inc.) so that the thickness after drying was 60 μm. Coated) and dried at 100 ° C. for 3 minutes to prepare an adhesive sheet.

[Comparative Example 2]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Comparative Example 1 except that 0.035 parts of an epoxy-based crosslinking agent was added.

[Comparative Example 3]
Synthetic polyisoprene latex (trade name “Sepolex IR-100K”, manufactured by Sumitomo Seika Co., Ltd.) 100 parts in solid content, aromatic modified terpene resin emulsion (trade name “Nanolet R-1050” as a tackifier, A water-dispersed pressure-sensitive adhesive composition was prepared by blending 60 parts of Yasuhara Chemical Co., Ltd. (softening point: 100 ° C.) with a solid content.

  Subsequently, the prepared water-dispersed pressure-sensitive adhesive composition was mixed with 0.5 part of an acrylic alkali thickening type thickener (trade name “Aron B-500”, manufactured by Toa Gosei Co., Ltd.) to increase the viscosity. The thickened water-dispersed pressure-sensitive adhesive composition is coated on a polyethylene terephthalate substrate (trade name “Lumirror S-10”, manufactured by Toray Industries, Inc.) having a thickness of 25 μm so that the thickness after drying becomes 60 μm. And this was dried at 100 degreeC for 3 minute (s), and the adhesive sheet was produced.

[Comparative Example 4]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that no epoxy-based crosslinking agent was added.

[Comparative Example 5]
An adhesive sheet was prepared in the same manner as in Example 8 except that no epoxy-based crosslinking agent was added.

[Comparative Example 6]
An adhesive sheet was prepared in the same manner as in Example 1 except that 18 parts of the tackifier was 6 parts and 0.04 part of the epoxy crosslinking agent was 0.01 parts.

[Comparative Example 7]
The same operation as in Example 1 was performed except that 30 parts of the synthetic polyisoprene latex was 50 parts, 18 parts of the tackifier was 10 parts, and 0.04 part of the epoxy crosslinking agent was 0.01 part, An adhesive sheet was prepared.

[Comparative Example 8]
The same operation as in Example 1 was carried out except that 30 parts of the synthetic polyisoprene latex was 50 parts, 18 parts of the tackifier was 30 parts, and 0.04 part of the epoxy crosslinking agent was 0.15 part, An adhesive sheet was prepared.

<Evaluation>
(1) Confirmation of compatibility between (meth) acrylic polymer and rubber component 70 parts by weight of water-dispersed (meth) acrylic polymer and 30 parts by weight of rubber latex are blended, A water-dispersed pressure-sensitive adhesive composition was prepared.

  Subsequently, the prepared water-dispersed pressure-sensitive adhesive composition was mixed with 0.5 part of an acrylic alkali thickening type thickener (trade name “Aron B-500”, manufactured by Toa Gosei Co., Ltd.) to increase the viscosity. The thickened water-dispersed pressure-sensitive adhesive composition was coated on a release sheet (trade name “Diafoil MRF-38”, manufactured by Mitsubishi Plastics Co., Ltd.) so that the thickness after drying was 60 μm. A pressure-sensitive adhesive sheet was prepared by drying at 3 ° C. for 3 minutes.

The pressure-sensitive adhesive sheet was peeled off from the release sheet, and only the pressure-sensitive adhesive layer was laminated to produce a laminate having a thickness of about 2 mm, and a sample punched out to φ7.9 mm was used as a measurement sample. The measurement sample was sandwiched between parallel disks (φ7.9 mm), and using a dynamic viscoelasticity measuring device (“Advanced Rheometric Expansion System” manufactured by Rheometric Scientific), applying a shear strain of a frequency of 1 Hz, the rate of temperature rise Storage elastic modulus (G ′) and loss elastic modulus (G ″) were measured in the range of −70 ° C. to 100 ° C. at 5 ° C./min. Also, storage elastic modulus (G ′) and loss elastic modulus (G ″) were measured. Thus, the loss tangent tan δ was calculated by the following calculation formula.
Loss tangent tan δ = G ″ / G ′

  A loss tangent curve was created by plotting the calculated loss tangent (tan δ) against temperature, and it was confirmed whether a peak derived from the (meth) acrylic polymer component and a peak derived from the rubber component existed. The case where both peaks did not exist was judged as compatible (◯), and the case where both peaks existed was judged as incompatible (x). Table 2 shows the evaluation results of the compatibility of the (meth) acrylic polymer and the rubber component used in the above-described Examples and Comparative Examples.

  As an example, FIG. 1 shows a graph showing the results of confirming the compatibility between the (meth) acrylic polymer used in Example 7 and the rubber component, and FIG. 2 shows a TEM image.

(2) Confirmation of compatibility between rubber component and tackifier A water-dispersed pressure-sensitive adhesive composition was prepared by blending 20 parts of a tackifier with a solid content with respect to 100 parts of a latex solid content. Subsequently, the prepared water-dispersed pressure-sensitive adhesive composition was mixed with 0.5 part of an acrylic alkali thickening type thickener (trade name “Aron B-500”, manufactured by Toa Gosei Co., Ltd.) to increase the viscosity. The thickened water-dispersed pressure-sensitive adhesive composition was coated on a release sheet (trade name “Diafoil MRF-38”, manufactured by Mitsubishi Plastics Co., Ltd.) so that the thickness after drying was 60 μm. A pressure-sensitive adhesive sheet was prepared by drying at 3 ° C. for 3 minutes.

  A slide glass ("Slide glass white edge polish" manufactured by Matsunami Glass Industry Co., Ltd .; thickness 1.3 mm) was bonded to one side of the prepared adhesive sheet, and the peeled sheet was peeled off as an evaluation sample. . The haze of this sample was measured using a haze meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.), and in accordance with JISK7136, haze (%) = Td / Tt × 100 (Td: diffuse transmittance) , Tt: total light transmittance). A case where the calculated haze was 50% or less (0 to 50%) was determined to be compatible, and a case where the calculated haze was higher than 50% was determined to be incompatible.

  The determination of compatibility is preferably determined when the haze of the produced pressure-sensitive adhesive sheet is 45% or less, and when it is higher than 45%, it is determined as incompatible, and when it is 40% or less, the compatibility is determined. It is more preferable to determine that the content is higher than 40% as incompatible.

  Table 3 shows the evaluation results of the haze value in the combination of the rubber component and the tackifier used in the above-described Examples and Comparative Examples.

(3) Confirmation of compatibility between (meth) acrylic polymer and tackifier To 20 parts of solid content of water-dispersed (meth) acrylic polymer, 20 parts of tackifier is blended. A water-dispersed pressure-sensitive adhesive composition was prepared. Subsequently, the prepared water-dispersed pressure-sensitive adhesive composition was mixed with 0.5 part of an acrylic alkali thickening type thickener (trade name “Aron B-500”, manufactured by Toa Gosei Co., Ltd.) to increase the viscosity. The thickened water-dispersed pressure-sensitive adhesive composition was coated on a release sheet (trade name “Diafoil MRF-38”, manufactured by Mitsubishi Plastics Co., Ltd.) so that the thickness after drying was 60 μm. A pressure-sensitive adhesive sheet was prepared by drying at 3 ° C. for 3 minutes.

  A slide glass ("Slide glass white edge polish" manufactured by Matsunami Glass Industry Co., Ltd .; thickness 1.3 mm) was bonded to one side of the prepared adhesive sheet, and the peeled sheet was peeled off as an evaluation sample. . The haze of this sample was measured using a haze meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.), and in accordance with JISK7136, haze (%) = Td / Tt × 100 (Td: diffuse transmittance) , Tt: total light transmittance). A case where the calculated haze was 50% or less (0 to 50%) was determined to be compatible, and a case where the calculated haze was higher than 50% was determined to be incompatible.

  The determination of compatibility is preferably determined when the haze of the produced pressure-sensitive adhesive sheet is 45% or less, and when it is higher than 45%, it is determined as incompatible, and when it is 40% or less, the compatibility is determined. It is more preferable to determine that the content is higher than 40% as incompatible.

  Table 4 shows the evaluation results of the haze value in the combination of the (meth) acrylic polymer and the tackifier used in the above-described Examples and Comparative Examples.

(4) Solvent insoluble content (gel fraction) of rubber latex
A water-dispersed pressure-sensitive adhesive composition in which rubber latex is mixed with 0.5 part of an acrylic alkali thickening type thickener (trade name “Aron B-500”, manufactured by Toa Gosei Co., Ltd.) to thicken and thicken. The product was coated on a release sheet (trade name “Diafoil MRF-38”, manufactured by Mitsubishi Plastics Co., Ltd.) so that the thickness after drying was 60 μm, and this was dried for 3 minutes at 100 ° C. A sheet was produced.

  The pressure-sensitive adhesive sheet was peeled off from the release sheet, and about 100 mg of the pressure-sensitive adhesive layer alone was added to a porous membrane made of tetrafluoroethylene resin having a pore diameter of 0.2 μm (trade name; NITOFLON NTF1122, manufactured by Nitto Denko Corporation) (Wa (mg )), Wrapped in a purse-like shape, tied the mouth with a kite string, and then measured the weight of the packet (Wb (mg)). The porous membrane and the kite string were weighed in advance (Wa (mg)).

This packet was placed in a 50-mL screw bottle, and the screw bottle was filled with toluene. After leaving this at room temperature for 7 days, the packet was taken out and dried at 130 ° C. for 2 hours, the weight of the packet was measured (Wc (mg)), and the gel fraction was determined by the following formula. The results are shown in Table 5.
Gel fraction (%) = (Wc−Wa) / (Wb−Wa) × 100

(5) Solvent insoluble content (gel fraction) of the adhesive layer
The water-dispersed pressure-sensitive adhesive compositions obtained in the examples and comparative examples were applied to a release sheet (trade name “Diafoil MRF-38”, manufactured by Mitsubishi Plastics Co., Ltd.) so that the thickness after drying was 60 μm. The coated sheet was dried at 100 ° C. for 3 minutes to prepare an adhesive sheet.

  The pressure-sensitive adhesive sheet was peeled off from the release sheet, and about 100 mg of the pressure-sensitive adhesive layer alone was placed on a porous membrane made of tetrafluoroethylene resin having a pore diameter of 0.2 μm (trade name; Nittolon NTF1122, manufactured by Nitto Denko Corporation), After wrapping in a drawstring shape and binding the mouth with a string, the weight of the wrap was measured (Wb (mg)). The porous membrane and the kite string were weighed in advance (Wa (mg)).

This packet was placed in a 50-mL screw bottle, and the screw bottle was filled with toluene. After leaving this at room temperature for 7 days, the packet was taken out and dried at 130 ° C. for 2 hours, the weight of the packet was measured (Wc (mg)), and the gel fraction was determined by the following formula. The results are shown in Table 6.
Gel fraction (%) = (Wc−Wa) / (Wb−Wa) × 100

(6) Solvent insoluble matter (gel fraction) of phase (acrylic phase) consisting of (meth) acrylic polymer
Based on the following formula, the solvent-insoluble content (gel fraction) of the acrylic phase was calculated.

(7) Adhesive strength The adhesive sheets obtained in each Example and each Comparative Example were cut into a size of 20 × 100 mm, and the adherend was subjected to measurement temperature atmosphere (25 ° C., −5 ° C., −15 ° C.). SUS304 stainless steel plate and polypropylene (PP) plate (trade name “PP-N-AN” manufactured by Shin-Kobe Electric Machinery Co., Ltd.) were attached to each other and pressure-bonded by reciprocating a 2 Kg roller. Thereafter, the sample is left at a measurement temperature atmosphere (25 ° C., −5 ° C., −15 ° C.) for 30 minutes, and in a 25 ° C., −5 ° C. and −15 ° C. atmosphere, at a peeling angle of 180 ° and a peeling speed of 300 mm / min. A peel test was conducted and the adhesive strength was measured. The results are shown in Table 6.

(8) Dynamic viscoelasticity of pressure-sensitive adhesive sheet The water-dispersed pressure-sensitive adhesive composition obtained in each example and each comparative example was separated from the release sheet (trade name “Diafoil MRF-” so that the thickness after drying was 60 μm. 38 ", manufactured by Mitsubishi Resin Co., Ltd.) and dried at 100 ° C for 3 minutes to prepare an adhesive sheet.

  The pressure-sensitive adhesive sheet was peeled off from the release sheet, and only the pressure-sensitive adhesive layer was laminated to produce a laminate having a thickness of about 2 mm, and a sample punched out to φ7.9 mm was used as a measurement sample.

  The measurement sample is sandwiched between parallel disks (φ7.9 mm), and using a “Advanced Rheometric Expansion System” manufactured by Rheometric Scientific, applying a shear strain of a frequency of 1 Hz at a rate of temperature rise of 5 ° C./min. The storage elastic modulus (G ′) was measured in the range of 70 ° C. to 100 ° C. The results are shown in FIG.

(9) Holding power The pressure-sensitive adhesive sheets obtained in each Example and each Comparative Example were attached to a phenol resin plate with a contact area of 10 mm × 20 mm, left at room temperature (25 ° C.) overnight, and then 40 ° C. After leaving for 30 minutes, the phenol resin plate was suspended, a uniform load of 500 g was applied to the free end of the adhesive tape, and the deviation distance (unit: mm) after leaving at 40 ° C. for 2 hours was measured. The results are shown in Table 6.

(10) End peelability (vs. acrylic board)
Release sheet (trade name “Diafoil MRF-38”, manufactured by Mitsubishi Plastics Co., Ltd.) so that the water-dispersed pressure-sensitive adhesive composition obtained in each Example and each Comparative Example had a thickness after drying of 60 μm. And a release sheet was further bonded onto the coating film. This was dried at 100 ° C. for 3 minutes to prepare an adhesive sheet.

  The pressure-sensitive adhesive sheet was peeled from the release sheet, adhered to an aluminum plate having a thickness of 0.4 mm (area 10 mm × 90 mm), and curved in an arc shape having a diameter of 50 mm.

  Next, the release sheet is peeled off, and then the pressure-sensitive adhesive sheet on which the aluminum plate is laminated is bonded to an acrylic plate using a laminator, and this is left at 23 ° C. for 24 hours, and the height at which the end of the aluminum plate is peeled off ( Unit: mm) was measured. The results are shown in Table 6.

(11) Terminal peelability (vs. PP board)
Release sheet (trade name “Diafoil MRF-38”, manufactured by Mitsubishi Plastics Co., Ltd.) so that the water-dispersed pressure-sensitive adhesive composition obtained in each Example and each Comparative Example had a thickness after drying of 60 μm. And a release sheet was further bonded onto the coating film. This was dried at 100 ° C. for 3 minutes to prepare an adhesive sheet.

  The pressure-sensitive adhesive sheet was peeled from the release sheet, adhered to an aluminum plate having a thickness of 0.3 mm (area 10 mm × 90 mm), and curved in an arc shape having a diameter of 50 mm.

  Next, the release sheet is peeled off, and then the pressure-sensitive adhesive sheet on which the aluminum plate is laminated is bonded to the PP plate using a laminator, and this is left at 23 ° C. for 1 hour.

(12) Constant load peelability The pressure-sensitive adhesive sheet obtained in each example and each comparative example is reciprocated once by a rubber roller weighing 2 kg with a contact area of 10 mm × 60 mm with respect to each of an acrylic plate and a PP plate. It stuck by the method and was left to stand at room temperature (25 degreeC) overnight. Thereafter, a uniform load of 50 g and 8 g was applied to the terminals, respectively, and the separation distance of each pressure-sensitive adhesive sheet from each adherend after being left for 5 hours and 3 hours was measured. The results are shown in Table 6.

  In Tables 1 to 3 and 5, “IR-100K” means synthetic polyisoprene latex (trade name “Sepolex IR-100K”, manufactured by Sumitomo Seika Co., Ltd.), and the loss tangent of the rubber component. The peak temperature is −53 ° C., “LX-111K” means polybutadiene latex (trade name “Nipol LX-111K”, manufactured by Nippon Zeon Co., Ltd.), and the loss tangent peak temperature is −75 ° C. is there.

  In Tables 1, 3, and 4, “R-1050”, “E-200NT”, and “T / C” are aromatic modified terpene resin emulsions (trade names “Nanolet R-1050”, Yasuhara Chemical Co., Ltd.) ), Softening point 100 ° C.), rosin-based tackifier (trade name “Tamanol E-200NT”, Arakawa Chemical Industries, softening point 145 ° C.), in Table 1, “T / C” is epoxy System cross-linking agent (trade name “TETRAD-C”, manufactured by Mitsubishi Gas Chemical Co., Ltd.).

  As shown in Table 6, the pressure-sensitive adhesive sheet according to the present invention has an adhesive strength to a PP plate at 25 ° C. of 5.0 N / 20 mm or more, and an adhesive strength to a PP plate at −5 ° C. of 5.0 N / 20 mm or more. It is confirmed that the pressure-sensitive adhesive sheet has an adhesive strength to a PP plate at −15 ° C. of 5.0 N / 20 mm or more, has excellent adhesion to a nonpolar adherend, and does not impair the characteristics even at low temperatures. It was done.

  At the same time, the pressure-sensitive adhesive sheet according to the present invention has an adhesive strength to the SUS plate at 25 ° C. of 4.0 N / 20 mm or more and an adhesive strength to the SUS plate at −5 ° C. of 5.0 N / 20 mm or more. In addition, it was confirmed that the pressure-sensitive adhesive sheet had an adhesive strength to the SUS plate at −15 ° C. of 6.0 N / 20 mm or more, had excellent adhesion to the polar adherend, and did not impair the characteristics even at low temperatures.

  Further, the pressure-sensitive adhesive sheet according to the present invention is excellent in holding properties without falling after 2 hours in a holding power test at 40 ° C.

  Furthermore, the pressure-sensitive adhesive sheet according to the present invention has a floating height of 5 mm or less after 24 hours in a terminal peelability test for an acrylic plate, and a lift height after 1 hour in a terminal peelability test for a PP plate is 5 mm. The terminal peeling property is excellent for both polar and nonpolar adherends.

  Furthermore, the pressure-sensitive adhesive sheet according to the present invention does not fall after 5 hours in the constant load peelability test for the acrylic plate, and does not fall after 3 hours in the constant load peelability test for the PP plate, It is excellent in constant load peelability for both polar and non-polar adherends.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The pressure-sensitive adhesive layer of the present invention is excellent in adhesion to nonpolar adherends such as polyethylene and polypropylene, and does not impair the characteristics even at low temperatures, and therefore can be suitably used for various pressure-sensitive adhesive sheets.

(7) Adhesive strength The adhesive sheets obtained in each Example and each Comparative Example were cut into a size of 20 × 100 mm, and the adherend was subjected to measurement temperature atmosphere (25 ° C., −5 ° C., −15 ° C.). SUS304 stainless steel plate is, and polypropylene (PP) plate (Shin-Kobe Electric Machinery Co., Ltd., trade name "PP-N-aN") bonded to the 2 k g roller and pressed by one reciprocation. Thereafter, the sample is left at a measurement temperature atmosphere (25 ° C., −5 ° C., −15 ° C.) for 30 minutes, and in a 25 ° C., −5 ° C. and −15 ° C. atmosphere, at a peeling angle of 180 ° and a peeling speed of 300 mm / min. A peel test was conducted and the adhesive strength was measured. The results are shown in Table 6.

Next, the release sheet is peeled off, and then the pressure-sensitive adhesive sheet on which the aluminum plate is laminated is bonded to the PP plate using a laminator, and this is left at 23 ° C. for 1 hour, and the height at which the end of the aluminum plate is peeled off ( Unit: mm) was measured. The results are shown in Table 6.

Claims (7)

A (meth) acrylic polymer obtained by polymerizing a monomer component mainly composed of (meth) acrylic acid alkyl ester having 1 to 18 carbon atoms in the alkyl group;
Latex containing a rubber component that is incompatible with the (meth) acrylic polymer and has a loss tangent peak temperature of −5 ° C. or lower, measured by dynamic viscoelasticity measurement at a shear strain of 1 Hz. When,
Containing at least a tackifier compatible with the rubber component,
The pressure-sensitive adhesive layer is formed using a water-dispersed pressure-sensitive adhesive composition in which the blending weight ratio of the (meth) acrylic polymer and the latex is 95/5 to 40/60 in terms of solid content,
The pressure-sensitive adhesive layer, wherein the toluene-insoluble content of the phase composed of the acrylic polymer in the pressure-sensitive adhesive layer is 25 to 85%, and the toluene-insoluble content of the pressure-sensitive adhesive layer is 15 to 60%. The softening point of the tackifier is 80 to 160 ° C., and the compounding amount of the tackifier is 5 to 100 parts by weight with respect to a total of 100 parts by weight of the (meth) acrylic polymer and the rubber component. The pressure-sensitive adhesive layer according to claim 1. The pressure-sensitive adhesive layer according to claim 1 or 2, wherein the monomer component containing the (meth) acrylic acid alkyl ester as a main component contains a reactive functional group-containing monomer. The pressure-sensitive adhesive layer according to claim 3, wherein the reactive functional group-containing monomer is an alkoxysilyl group-containing vinyl monomer. The pressure-sensitive adhesive layer according to claim 3, wherein the water-dispersed pressure-sensitive adhesive composition contains a crosslinking agent that reacts with the reactive functional group-containing monomer. The pressure-sensitive adhesive according to any one of claims 1 to 5, wherein the rubber component contained in the latex is at least one selected from the group consisting of natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, and styrene butadiene rubber. layer. The adhesive sheet which has an adhesive layer in any one of Claims 1-6.