JP2017155243A - Adhesive composition and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water dispersion type acrylic adhesive composition capable of forming an adhesive layer excellent in antistatic property, re-detachability (light detachability), and appearance.SOLUTION: The water dispersion type acrylic adhesive composition for re-detachment contains an acryl emulsion polymer constituted by (meth)acrylic acid alkyl ester of 70 to 99.5 wt.% and a carboxyl group-containing unsaturated monomer of 0.5 to 10 wt.% as monomer components, a crosslinking agent, an ionic compound, and a nonionic surfactant having HLB value of 6 or more.SELECTED DRAWING: None

Description

  The present invention relates to a water-dispersed acrylic pressure-sensitive adhesive composition capable of forming a re-peelable pressure-sensitive adhesive layer. Specifically, the present invention relates to a water-dispersed acrylic pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in antistatic properties, removability (light releasability), and appearance characteristics. Moreover, it is related with the adhesive sheet which provided the adhesive layer which consists of the said adhesive composition.

  In the manufacturing and processing processes of optical members (optical materials) including optical films such as polarizing plates, retardation plates, and antireflection plates, for the purpose of surface scratches, dirt prevention, cutting workability improvement, crack suppression, etc. A surface protective film is used by being attached to the surface of an optical member (see Patent Documents 1 and 2). As these surface protective films, a removable pressure-sensitive adhesive sheet in which a removable pressure-sensitive adhesive layer is provided on the surface of a plastic film substrate is generally used.

  Conventionally, solvent-type acrylic pressure-sensitive adhesives have been used as pressure-sensitive adhesives for these surface protective film applications (see Patent Documents 1 and 2), but these solvent-type acrylic pressure-sensitive adhesives contain organic solvents. Therefore, from the viewpoint of work environment at the time of coating, conversion to a water-dispersed acrylic pressure-sensitive adhesive has been attempted (see Patent Documents 3 to 5).

  These surface protective films are required to exhibit sufficient adhesiveness while being attached to the optical member. Furthermore, since it peels after using in the manufacturing process of an optical member, etc., the outstanding peelability (removability) is calculated | required. In order to have excellent removability, it is necessary that the peel force is small (light peeling).

  In general, since the surface protective film and the optical member are made of a plastic material, the surface protection film and the optical member have high electrical insulation, and generate static electricity during friction and peeling. Therefore, static electricity is generated when the surface protective film is peeled off from the optical member such as a polarizing plate. When voltage is applied to the liquid crystal while the static electricity generated at this time remains, the orientation of the liquid crystal molecules is changed. There is a problem that the panel is lost and the panel is lost.

  Furthermore, the presence of static electricity may cause problems such as sucking dust and debris and problems of lowering workability. Therefore, various antistatic treatments are applied to the surface protective film in order to solve the above problems.

  As an attempt to suppress electrostatic charging, there is a method in which a low molecular surfactant is added to an adhesive, and the surfactant is transferred from the adhesive to an object to be protected to prevent charging (for example, see Patent Document 6). It is disclosed. However, in such a method, the added low-molecular-weight surfactant easily bleeds on the surface of the pressure-sensitive adhesive, and when applied to a surface protective film, there is a concern about contamination of the adherend (protected body).

  Moreover, the adhesive composition containing an ionic liquid is disclosed with the polymer which uses a reactive surfactant as a monomer component (patent document 7). The pressure-sensitive adhesive layer obtained here has an ether group and an ester group contained in the reactive surfactant coordinated with the ionic liquid, thereby suppressing the bleed out of the ionic liquid, providing antistatic properties and low contamination. Realized. However, the pressure-sensitive adhesive layer here may cause problems in appearance due to the formation of dents or gels on the surface, which is inferior in workability in the process of visual inspection of optical members.

Japanese Patent Laid-Open No. 11-961 JP 2001-64607 A JP 2001-131512 A JP 2003-27026 A Japanese Patent No. 3810490 JP-A-9-165460 JP 2007-217441 A

  As described above, none of these can solve the above problems in a well-balanced manner, and surface protection that has antistatic properties and the like in the technical field related to electronic equipment in which charging and contamination are particularly serious problems. It is difficult to meet the demand for further improvements to the film, and water-dispersed acrylic adhesives with excellent antistatic properties, removability (light releasability), and appearance characteristics have not been obtained. It is.

  Accordingly, an object of the present invention is to provide a water-dispersed acrylic pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having excellent antistatic properties, removability (light releasability), and appearance characteristics. It is in. Moreover, it is providing the adhesive sheet which has an adhesive layer by the said adhesive composition.

  As a result of intensive studies to achieve the above object, the present inventors have determined that a specific acrylic emulsion polymer obtained from a raw material monomer having a specific composition, a crosslinking agent, an ionic compound, and a nonionic property having a specific HLB value. It was found that a water-dispersed acrylic pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having a surfactant as a constituent component and excellent in antistatic properties, removability (light releasability), and appearance characteristics can be obtained. The present invention has been completed.

  That is, the water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling of the present invention (sometimes simply referred to as “pressure-sensitive adhesive composition”) comprises (meth) acrylic acid alkyl ester 70 to 99.5% by weight, and Acrylic emulsion-based polymer composed of 0.5 to 10% by weight of a carboxyl group-containing unsaturated monomer as a monomer component, a crosslinking agent, an ionic compound, and a nonionic surfactant having an HLB value of 6 or more. It is characterized by that.

  In the pressure-sensitive adhesive composition of the present invention, the nonionic surfactant preferably contains an acetylene structure.

  In the pressure-sensitive adhesive composition of the present invention, the nonionic surfactant preferably includes an acetylene diol structure.

  In the pressure-sensitive adhesive composition of the present invention, the ionic compound preferably contains an anion containing a fluorine atom.

  In the pressure-sensitive adhesive composition of the present invention, the ionic compound preferably contains an anion containing a nitrogen atom.

  In the pressure-sensitive adhesive composition of the present invention, the ionic compound preferably contains an anion having a sulfonyl group.

In the pressure-sensitive adhesive composition of the present invention, the ionic compound is an ionic liquid, and the ionic liquid is at least one cation selected from the group consisting of cations represented by the following formulas (A) to (E): It is preferable to contain.

[R _a in Formula (A) represents a hydrocarbon group having 4 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, and R _b and R _c May be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. However, when the nitrogen atom contains a double bond, there is no R _c . ]
[R _d in Formula (B) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, and R _e , R _f And R _g may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. ]
[R _h in Formula (C) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a heteroatom, R _i , R _j , And R _k may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. ]
[Z in Formula (D) represents a nitrogen, sulfur, or phosphorus atom, and R ₁ , R _m , R _n , and R _o are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms. In addition, a functional group in which a part of the hydrocarbon group is substituted with a hetero atom may be used. However, when Z is a sulfur atom, there is no _Ro . ]
[R _P in the formula (E) represents a hydrocarbon group having 1 to 18 carbon atoms, a part of the hydrocarbon group may be substituted by a functional group with a heteroatom. ]

  In the pressure-sensitive adhesive composition of the present invention, the ionic liquid comprises an imidazolium-containing salt type, a pyridinium salt-containing type, a morpholinium salt-containing type, a pyrrolidinium salt-containing type, a piperidinium salt-containing type, an ammonium-containing salt type, or a phosphonium-containing salt. It is preferably at least one selected from the group consisting of a mold and a sulfonium-containing salt mold.

In the pressure-sensitive adhesive composition of the present invention, the ionic liquid preferably contains one or more cations represented by the following general formulas (a) to (d).

[R ₁ in Formula (a) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₂ represents hydrogen or a hydrocarbon group having 1 to 5 carbon atoms. ]
[R ₃ in Formula (b) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₄ represents hydrogen or a hydrocarbon group having 1 to 5 carbon atoms. ]
[R ₅ in Formula (c) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₆ represents hydrogen or a hydrocarbon group having 1 to 5 carbon atoms. ]
[R ₇ in Formula (d) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₈ represents hydrogen or a hydrocarbon group having 1 to 5 carbon atoms. ]

  In the pressure-sensitive adhesive composition of the present invention, the ionic compound is preferably an alkali metal salt.

  In the pressure-sensitive adhesive composition of the present invention, the alkali metal salt is preferably a lithium salt.

  The pressure-sensitive adhesive composition of the present invention preferably contains 0.5 to 3 parts by weight of the ionic compound with respect to 100 parts by weight of the solid content of the acrylic emulsion polymer.

  The pressure-sensitive adhesive composition of the present invention preferably contains 0.01 to 10 parts by weight of the nonionic surfactant with respect to 100 parts by weight of the solid content of the acrylic emulsion polymer.

  The pressure-sensitive adhesive composition of the present invention preferably contains 0.2 to 1 part by weight of the ether group-containing polysiloxane with respect to 100 parts by weight of the solid content of the acrylic emulsion polymer.

  The pressure-sensitive adhesive composition of the present invention is preferably a polymer obtained by polymerizing the acrylic emulsion polymer using a reactive emulsifier containing a radical polymerizable functional group in the molecule.

  In the pressure-sensitive adhesive composition of the present invention, the acrylic emulsion polymer preferably has an average particle diameter of 130 nm to 1000 nm.

  The pressure-sensitive adhesive sheet of the present invention preferably has a pressure-sensitive adhesive layer formed from the re-peeling water-dispersed acrylic pressure-sensitive adhesive composition on at least one side of the substrate.

  The pressure-sensitive adhesive sheet of the present invention is preferably a surface protective film for optical members.

  The pressure-sensitive adhesive composition of the present invention contains a specific acrylic emulsion polymer obtained from a raw material monomer having a specific composition, a crosslinking agent, an ionic compound, and a nonionic surfactant having a specific HLB value as constituent components. Therefore, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is excellent in excellent adhesiveness (adhesiveness), antistatic property, removability (lightly releasable), and appearance characteristics. For this reason, the pressure-sensitive adhesive composition of the present invention is particularly useful as a surface protection application for optical films and the like.

Schematic diagram of potential measurement unit

  Hereinafter, embodiments of the present invention will be described in detail.

  The water-dispersible acrylic pressure-sensitive adhesive composition (pressure-sensitive adhesive composition) for re-peeling according to the present invention comprises (meth) acrylic acid alkyl ester 70 to 99.5% by weight and carboxyl group-containing unsaturated monomer 0.5 to 10 It is characterized by containing an acrylic emulsion polymer constituted as a monomer component, a crosslinking agent, an ionic compound, and a nonionic surfactant having an HLB value of 6 or more. The “water-dispersed type” means that it can be dispersed in an aqueous medium, that is, an adhesive composition that can be dispersed in an aqueous medium. The aqueous medium is a medium (dispersion medium) containing water as an essential component, and may be a mixture of water and a water-soluble organic solvent in addition to water alone. The pressure-sensitive adhesive composition of the present invention may be a dispersion using the aqueous medium or the like.

[Acrylic emulsion polymer]
The acrylic emulsion polymer is a polymer composed of 70 to 99.5 wt% of (meth) acrylic acid alkyl ester and 0.5 to 10 wt% of carboxyl group-containing unsaturated monomer as raw material monomers. is there. The acrylic emulsion polymer can be used alone or in combination of two or more. In the present invention, “(meth) acryl” means “acryl” and / or “methacryl”.

  The (meth) acrylic acid alkyl ester is used as a main monomer component, and mainly plays a role of expressing basic characteristics as a pressure-sensitive adhesive (or pressure-sensitive adhesive layer) such as pressure-sensitive adhesiveness (adhesiveness) and peelability. Among them, acrylic acid alkyl esters tend to give flexibility to the polymer forming the pressure-sensitive adhesive layer, and exhibit the effect of developing adhesiveness and adhesiveness to the pressure-sensitive adhesive layer. There exists a tendency which gives the polymer to form hardness and exhibits the effect which adjusts the removability of an adhesive layer. Although it does not specifically limit as said (meth) acrylic-acid alkylester, A C1-C16 (more preferably 2-10, more preferably 4-8) linear, branched or cyclic alkyl group is preferable. (Meth) acrylic acid alkyl ester having

  Among them, as the alkyl acrylate ester, for example, an alkyl acrylate ester having an alkyl group having 2 to 14 carbon atoms (more preferably 4 to 8) is preferable, such as n-butyl acrylate, isobutyl acrylate, acrylic acid s. -It has a linear or branched alkyl group such as butyl, isoamyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, or isononyl acrylate. Examples include acrylic acid alkyl esters. Of these, 2-ethylhexyl acrylate is preferable.

  Further, as the alkyl methacrylate, for example, alkyl methacrylate having an alkyl group having 2 to 16 carbon atoms (more preferably 2 to 8) is preferable, such as ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, methacrylic acid. Methacrylic acid alkyl ester having a linear or branched alkyl group such as n-butyl acid, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, bornyl methacrylate, isobornyl methacrylate And an alicyclic methacrylic acid alkyl ester.

  The said (meth) acrylic-acid alkylester can be suitably selected according to the target adhesiveness etc., and can be used individually or in combination of 2 or more types.

  Content of the said (meth) acrylic-acid alkylester is 70-99.5 weight% in the total amount (total raw material monomer) (100 weight%) of the raw material monomer which comprises the acrylic emulsion type polymer of this invention, Preferably it is 85-98 weight%, More preferably, it is 87-96 weight%. It is preferable that the content is 70% by weight or more because the adhesiveness and removability of the adhesive layer are improved. On the other hand, when the content exceeds 99.5% by weight, the appearance of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition may deteriorate due to a decrease in the content of the carboxyl group-containing unsaturated monomer. In addition, when 2 or more types of (meth) acrylic-acid alkylesters are used, the total amount (total amount) of all the (meth) acrylic-acid alkylesters should just satisfy the said range.

  The carboxyl group-containing unsaturated monomer can exhibit a function of forming a protective layer on the surface of the emulsion particles made of the acrylic emulsion polymer of the present invention and preventing shearing of the particles. This effect is further improved by neutralizing the carboxyl group with a base. The stability of the particles against shear fracture is more generally referred to as mechanical stability. In addition, by combining one or two or more crosslinking agents that react with carboxyl groups (in the present invention, water-insoluble crosslinking agents are preferred), it also acts as a crosslinking point in the pressure-sensitive adhesive layer forming stage by water removal. You can also Furthermore, the adhesiveness (anchoring property) with a base material can also be improved through a crosslinking agent (water-insoluble crosslinking agent). Examples of such carboxyl group-containing unsaturated monomers include (meth) acrylic acid (acrylic acid, methacrylic acid), itaconic acid, maleic acid, fumaric acid, crotonic acid, carboxyethyl acrylate, carboxypentyl acrylate, and the like. . The carboxyl group-containing unsaturated monomer includes acid anhydride group-containing unsaturated monomers such as maleic anhydride and itaconic anhydride. Among these, acrylic acid is preferable because the relative concentration on the particle surface is high and it is easy to form a denser protective layer.

  The content of the carboxyl group-containing unsaturated monomer is preferably 0.5 to 10% by weight in the total amount of raw material monomers (total raw material monomers) (100% by weight) constituting the acrylic emulsion polymer of the present invention, preferably Is 1 to 5% by weight, more preferably 2 to 4% by weight. By controlling the content to 10% by weight or less, an increase in interaction with a functional group present on the surface of a polarizing plate or the like as an adherend (protected body) after the pressure-sensitive adhesive layer is formed is suppressed. Therefore, it is preferable because an increase in peel force (adhesive strength) over time can be suppressed and peelability (removability) is improved. In addition, when the content exceeds 10% by weight, the carboxyl group-containing unsaturated monomer (for example, acrylic acid) is generally water-soluble, and thus polymerizes in water to cause thickening (increased viscosity). There is. In addition, when a large number of carboxyl groups are present in the skeleton of the acrylic emulsion polymer, it interacts with a water-insoluble (hydrophobic) ionic liquid blended as an antistatic agent, impeding ionic conduction, and adherend It is presumed that antistatic performance on the surface cannot be obtained, which is not preferable. On the other hand, the content of 0.5% by weight or more is preferable because the mechanical stability of the emulsion particles is improved. Moreover, since the adhesiveness (throwing property) of an adhesive layer and a base material improves and adhesive residue can be suppressed, it is preferable.

  As the monomer component (raw material monomer) constituting the acrylic emulsion polymer, for the purpose of imparting a specific function, other monomer components other than the essential component (meth) acrylic acid alkyl ester and carboxyl group-containing unsaturated monomer May be used in combination. Examples of such a monomer component include amide group-containing monomers such as (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, and N, N- for the purpose of improving cohesion. Amino group-containing monomers such as dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate may be added (used) in an amount of about 0.1 to 15% by weight. In addition, for purposes such as refractive index adjustment and reworkability, (meth) acrylic acid aryl esters such as phenyl (meth) acrylate; vinyl esters such as vinyl acetate and vinyl propionate; styrene monomers such as styrene, You may add (use) in the ratio of 15 weight% or less. Furthermore, for the purpose of improving emulsion particle cross-linking and cohesive strength, epoxy group-containing monomers such as glycidyl (meth) acrylate and allyl glycidyl ether, and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate and divinylbenzene, You may add (use) in the ratio of less than weight%. Furthermore, in order to form hydrazide bridge | crosslinking in combination with a hydrazide type | system | group crosslinking agent and to improve especially low pollution property, diacetone acrylamide (DAAM), allyl acetoacetate, 2- (acetoacetoxy) ethyl (meth) acrylate, etc. A keto group-containing unsaturated monomer may be added (used) in a proportion of less than 10% by weight (preferably 0.5 to 5% by weight).

  Moreover, as said other monomer component, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl Hydroxyl group-containing unsaturated monomers such as vinyl ether, 4-hydroxybutyl vinyl ether and diethylene glycol monovinyl ether may be used. The hydroxyl group-containing unsaturated monomer preferably has a smaller blending amount (use amount) from the viewpoint of further reducing whitening contamination. Specifically, the amount of the hydroxyl group-containing unsaturated monomer is preferably less than 1% by weight, more preferably less than 0.1% by weight, and still more preferably substantially free (for example, less than 0.05% by weight). Is preferred. However, when the purpose is to introduce cross-linking points such as cross-linking of hydroxyl groups and isocyanate groups or cross-linking of metal cross-links, about 0.01 to 10% by weight may be added (used).

  In addition, the compounding quantity (usage amount) of said other monomer component is content in the total amount (total raw material monomer) (100 weight%) of the raw material monomer which comprises an acrylic emulsion type polymer.

  In particular, from the viewpoint of improving the appearance of the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) obtained from the pressure-sensitive adhesive composition of the present invention, as a monomer component (raw material monomer) constituting an acrylic emulsion polymer, methyl methacrylate, isovol It is preferable to use at least one monomer selected from the group consisting of nyl acrylate, N, N-diethylacrylamide and vinyl acetate (hereinafter sometimes referred to as “methyl methacrylate”), particularly preferably methacrylic. Methyl acid. When these monomers are used, the stability of the emulsion particles is increased, the gel (aggregate) can be reduced, and when a water-insoluble crosslinking agent is used as a crosslinking agent, This increases the affinity with the water-insoluble crosslinking agent, improves the dispersibility of the emulsion particles, and reduces the depression of the pressure-sensitive adhesive layer due to poor dispersion. The content of the monomer (such as methyl methacrylate) in the total amount of raw material monomers (total raw material monomer) (100% by weight) constituting the acrylic emulsion polymer is preferably 0.5 to 15% by weight, more preferably. Is 1 to 10% by weight, more preferably 2 to 5% by weight. If the content is less than 0.5% by weight, the effect of improving the appearance may not be obtained. If the content exceeds 15% by weight, the polymer forming the pressure-sensitive adhesive layer becomes hard and may cause a decrease in adhesion. When the raw material monomer constituting the acrylic emulsion polymer contains two or more monomers selected from the group consisting of methyl methacrylate, isobornyl acrylate, N, N-diethylacrylamide and vinyl acetate, The total amount (total content) of the contents of methyl acid, isobornyl acrylate, N, N-diethylacrylamide and vinyl acetate should satisfy the above range.

  The acrylic emulsion polymer in the present invention is obtained by emulsion polymerization of the above raw material monomer (monomer mixture) with an emulsifier and a polymerization initiator. Furthermore, a chain transfer agent may be used to adjust the molecular weight of the acrylic emulsion polymer.

  The acrylic emulsion polymer of the present invention can be obtained by emulsion polymerization of the raw material monomer (monomer mixture) with an emulsifier and a polymerization initiator.

[Reactive emulsifier]
As an emulsifier used for emulsion polymerization of the acrylic emulsion polymer of the present invention, it is preferable to use a reactive emulsifier having a radical polymerizable functional group introduced into the molecule (a reactive emulsifier containing a radical polymerizable functional group). These emulsifiers are used alone or in combination of two or more.

  The reactive emulsifier containing a radical polymerizable functional group (hereinafter referred to as “reactive emulsifier”) is an emulsifier containing at least one radical polymerizable functional group in a molecule (in one molecule). The reactive emulsifier is not particularly limited, and various reactive emulsifiers having a radical polymerizable functional group such as vinyl group, propenyl group, isopropenyl group, vinyl ether group (vinyloxy group), and allyl ether group (allyloxy group). 1 type or 2 or more types can be selected and used. Use of the reactive emulsifier is preferable because the emulsifier is incorporated into the polymer and contamination from the emulsifier is reduced.

  Examples of the reactive emulsifier include nonionic anionic emulsifiers such as sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium polyoxyethylene alkyl sulfosuccinate (nonionic). A reactive emulsifier having a form in which a radical polymerizable functional group (radical reactive group) such as propenyl group or allyl ether group is introduced into an anionic emulsifier having a hydrophilic hydrophilic group) (or corresponding to the above form) Can be mentioned. Hereinafter, a reactive emulsifier having a form in which a radical polymerizable functional group is introduced into an anionic emulsifier is referred to as an “anionic reactive emulsifier”. A reactive emulsifier having a form in which a radical polymerizable functional group is introduced into a nonionic anionic emulsifier is referred to as a “nonionic anionic reactive emulsifier”.

  In particular, when an anionic reactive emulsifier (particularly, a nonionic anionic reactive emulsifier) is used, the emulsifier is incorporated into the polymer, so that the low contamination property can be improved. Furthermore, particularly when the water-insoluble crosslinking agent of the present invention is a polyfunctional epoxy-based crosslinking agent having an epoxy group, the reactivity of the crosslinking agent can be improved by its catalytic action. When an anionic reactive emulsifier is not used, the crosslinking reaction is not completed by aging, and there may be a problem that the peeling force (adhesive strength) of the pressure-sensitive adhesive layer changes with time. Further, since the anionic reactive emulsifier is incorporated in the polymer, it is generally used as a catalyst for an epoxy-based crosslinking agent, such as a quaternary ammonium compound (for example, see JP-A-2007-31585). Since it does not precipitate on the surface of the adherend and cannot cause whitening contamination, it is preferable.

  Examples of such reactive emulsifiers include trade name “Adekaria Soap SE-10N” (manufactured by ADEKA Corporation), trade name “Aqualon HS-10” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and trade name “Aqualon HS” Commercial products such as “-05” (Daiichi Kogyo Seiyaku Co., Ltd.) and trade name “AQUALON HS-1025” (Daiichi Kogyo Seiyaku Co., Ltd.) can also be used.

In particular, since impurity ions may become a problem, it is desirable to remove the impurity ions and use an emulsifier having an SO ₄ ^2- ion concentration of 100 μg / g or less. In the case of an anionic emulsifier, it is desirable to use an ammonium salt emulsifier. As a method for removing impurities from the emulsifier, an appropriate method such as an ion exchange resin method, a membrane separation method, or a precipitation filtration method for impurities using alcohol can be used.

  The compounding amount (usage amount) of the reactive emulsifier is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of raw material monomers (total raw material monomers) constituting the acrylic emulsion polymer of the present invention, More preferably, it is 0.5-6 weight part, More preferably, it is 1-4.5 weight part. A blending amount of 0.1 part by weight or more is preferable because stable emulsification can be maintained. On the other hand, when the blending amount is 10 parts by weight or less, the cohesive force of the pressure-sensitive adhesive (pressure-sensitive adhesive layer) is improved, contamination to the adherend can be suppressed, and contamination by the emulsifier can be suppressed, which is preferable.

  The polymerization initiator used for emulsion polymerization of the acrylic emulsion polymer is not particularly limited. For example, 2,2′-azobisisobutyronitrile, 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'- Azo polymerization initiators such as azobis (N, N'-dimethyleneisobutylamidine); persulfates such as potassium persulfate and ammonium persulfate; peroxidations such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide Physical polymerization initiators; redox initiators in combination with peroxides and reducing agents, for example peroxides and Ascos Combinations with binoic acid (such as a combination of hydrogen peroxide and ascorbic acid), combinations of peroxide and iron (II) salt (such as a combination of hydrogen peroxide and iron (II) salt), persulfate A redox polymerization initiator based on a combination of a salt and sodium hydrogen sulfite can be used.

  The blending amount (use amount) of the polymerization initiator can be appropriately determined according to the type of the initiator and the raw material monomer, and is not particularly limited. However, the amount of the raw material monomer constituting the acrylic emulsion polymer of the present invention is not particularly limited. The amount is preferably 0.01 to 1 part by weight, more preferably 0.02 to 0.5 part by weight, based on 100 parts by weight of the total amount (total raw material monomers). In addition, regarding the blending (dropping) of the polymerization initiator, there are a method of total amount dropping polymerization that drops all at once and a two-stage polymerization that drops in two portions, but the former has a smaller particle size of the emulsion. Since it is easy to control and works advantageously in antistatic properties, it is a preferred embodiment.

  Emulsion polymerization of the acrylic emulsion-based polymer of the present invention can be performed by emulsifying the monomer component in water and then emulsion polymerization according to a conventional method. Thereby, the aqueous dispersion (polymer emulsion) which contains the said acrylic emulsion type polymer as a base polymer can be prepared. The emulsion polymerization method is not particularly limited, and for example, a known emulsion polymerization method such as a batch charging method (batch polymerization method), a monomer dropping method, or a monomer emulsion dropping method can be employed. In addition, in the monomer dropping method and the monomer emulsion dropping method, continuous dropping (total amount dropping) or divided dropping (including two-stage dropping. In addition, dividing dropping is a dropping speed such as a slow primary dropping and a fast secondary dropping. Or a method of dividing the polymerization process by changing the amount of dripping.) Is appropriately selected, and continuous dripping (total amount dripping) is particularly preferable. By employing continuous dripping (total dripping), the average particle diameter of the acrylic emulsion polymer used in the present invention can be adjusted to a desired range, which is a preferred embodiment. The polymerization by two-stage dropping may be referred to as two-stage (dropping) polymerization.

  The total amount dropping polymerization will be specifically described. When the total amount dropping polymerization is adopted, since there is no sufficient emulsifier capable of forming micelles in the reaction system (an aqueous solution to which a polymerization initiator is added) at the beginning of the dropping, the reaction Does not occur (since emulsion dripping polymerization occurs inside the emulsifier micelle), when a certain amount of monomer emulsion is dripped and reaches the concentration that forms micelles (critical micelle concentration), there are many monomers in the system Therefore, the particle size becomes large when reacted. Therefore, it is possible to adjust the average particle diameter to a desired range by controlling the amount of emulsifier initially charged in consideration of the critical micelle concentration of the emulsifier. These methods can be appropriately combined. Although reaction conditions etc. are selected suitably, it is preferable that polymerization temperature is about 40-95 degreeC, for example, and it is preferable that polymerization time is about 30 minutes-about 24 hours. The average particle size of the acrylic emulsion polymer can also be adjusted by increasing the dropping rate of the monomer emulsion or increasing the polymerization temperature.

  The average particle size of the emulsion particles can be controlled by the type and concentration of the emulsifier added during polymerization, the concentration of the polymerization initiator, and the like. Here, the average particle diameter of the emulsion particles is based on a volume-based median diameter value obtained by measurement with a laser diffraction / scattering particle size distribution measuring apparatus.

  The average particle size of the acrylic emulsion polymer of the present invention is preferably 130 to 1000 nm, more preferably 150 to 500 nm, and still more preferably 200 to 450 nm. When the average particle diameter of the acrylic emulsion polymer is within the above range, the antistatic property can be improved, which is useful.

  The solvent-insoluble content of the acrylic emulsion polymer (ratio of solvent-insoluble component, sometimes referred to as “gel fraction”) is preferably 70% by weight (%) or more, more preferably 75% by weight or more, and still more preferably. 80% by weight or more. If the solvent-insoluble content is less than 70% by weight, the acrylic emulsion polymer contains a large amount of low molecular weight, and therefore the low molecular weight component in the pressure-sensitive adhesive layer cannot be sufficiently reduced only by the effect of crosslinking. In some cases, adherend contamination derived from the above occurs, or the adhesive strength becomes too high. The solvent-insoluble content can be controlled by the polymerization initiator, reaction temperature, type of emulsifier and raw material monomer, and the like. Although the upper limit of the said solvent insoluble content is not specifically limited, For example, it is 99 weight%.

  In the present invention, the solvent-insoluble content of the acrylic emulsion polymer is a value calculated by the following “method for measuring the solvent-insoluble content”.

(Measurement method of solvent insoluble matter)
About 0.1 g of an acrylic emulsion polymer was collected, wrapped in a porous tetrafluoroethylene sheet (trade name “NTF1122”, manufactured by Nitto Denko Corporation) with an average pore diameter of 0.2 μm, and then tied with a kite string. The weight is measured, and this weight is defined as the weight before immersion. The weight before immersion is the total weight of the acrylic emulsion polymer (collected above), the tetrafluoroethylene sheet, and the kite string. Further, the total weight of the tetrafluoroethylene sheet and the kite string is also measured, and this weight is defined as the wrapping weight.

Next, the above acrylic emulsion polymer wrapped with a tetrafluoroethylene sheet and tied with a kite string (referred to as “sample”) is placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23 ° C. for 7 days. Put. Then, the sample (after ethyl acetate treatment) is taken out from the container, transferred to an aluminum cup, dried in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, the weight is measured, and the weight is immersed. After weight. And a solvent insoluble content is computed from a following formula.
Solvent insoluble content (% by weight) = (ab) / (c−b) × 100
(In the above formula, a is the weight after immersion, b is the weight of the wrapping bag, and c is the weight before immersion.)

  The weight average molecular weight (Mw) of the solvent-soluble component (sometimes referred to as “sol component”) of the acrylic emulsion polymer of the present invention is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, More preferably, it is 60,000 to 100,000. When the weight average molecular weight of the solvent-soluble component of the acrylic emulsion polymer is 40,000 or more, the wettability of the pressure-sensitive adhesive composition to the adherend is improved, and the adhesion to the adherend is improved. In addition, since the weight average molecular weight of the solvent-soluble component of the acrylic emulsion polymer is 200,000 or less, the residual amount of the pressure-sensitive adhesive composition on the adherend is reduced, and the low contamination property to the adherend is improved. To do.

  The weight average molecular weight of the solvent-soluble component of the acrylic emulsion polymer is determined by air-drying the treated solution (ethyl acetate solution) after the ethyl acetate treatment obtained in the measurement of the solvent-insoluble component of the acrylic emulsion polymer at room temperature. The sample (solvent-soluble content of the acrylic emulsion polymer) obtained by the measurement can be obtained by measurement by GPC (gel permeation chromatography). Specific methods for measuring include the following methods.

  Specific methods for measuring the weight average molecular weight by GPC (gel permeation chromatography) include the following methods.

[Measuring method]
The GPC measurement is performed using a GPC apparatus “HLC-8220GPC” manufactured by Tosoh Corporation, and the molecular weight is determined by a polystyrene conversion value. The measurement conditions are as follows.
Sample concentration: 0.2% by weight (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column: 1 TSKguardcolumn SuperHZ-H + 2 TSKgel SuperHZM-H Reference column; 1 TSKgel SuperH-RC Detector: Differential refractometer

[Nonionic surfactant]
The pressure-sensitive adhesive composition of the present invention contains a nonionic surfactant having an HLB (Hydrophile-Lipophile-Blance) value of 6 or more as an essential component. In addition, HLB value is Hydrophile-Lipophile Balance by Griffin, and is a value representing the degree of affinity of surfactants to water and oil. For the definition of the HLB value, see W.H. C. Griffin: J. Soc. Cosmetic Chemists, 1, 311 (1949), Koshimin Takahashi, Yoshiro Namba, Motoko Koike, Masao Kobayashi, “Surfactant Handbook”, 3rd edition, Kogakushoshosha Publishing Co., Ltd., November 25, 1972 , P179 to 182 and the like, and the ratio between hydrophilicity and lipophilicity is represented by a numerical value between 0 and 20.

  The HLB value of the nonionic surfactant is 6 or more, preferably 7 or more, more preferably 8 or more, and particularly preferably 13 or more. In general, the HLB value is preferably 18 or less, and more preferably 17 or less. The nonionic surfactant having an HLB value of 6 or more means high hydrophilicity, that is, high polarity, and thus interacts with an ionic compound that is an essential component of the pressure-sensitive adhesive composition of the present invention. Thus, the effect of unevenly distributing the ionic compound on the surface of the pressure-sensitive adhesive layer is exhibited, and the antistatic effect can be improved, which is useful. Furthermore, since the said nonionic surfactant has a leveling effect, it can also contribute to the improvement of the external appearance of the adhesive layer surface.

  The nonionic surfactant preferably contains an acetylene structure, and more preferably contains an acetylene diol structure. By having an acetylene diol structure among acetylene structures, a pressure-sensitive adhesive layer or a pressure-sensitive adhesive sheet having excellent leveling properties and good appearance can be obtained, which is useful. Examples of the nonionic surfactant having an acetylenic diol structure include acetylenic diol compounds and / or derivatives thereof (hereinafter sometimes referred to as “acetylene diol compounds and the like”).

  The ionic compound, which is an essential component in the pressure-sensitive adhesive composition of the present invention, may be difficult to uniformly mix and disperse when dispersed in water, resulting in a state where the ionic compound is scattered non-uniformly. Although contamination to the body is likely to occur, the occurrence of these problems can be prevented by containing the acetylenic diol compound or the like. Further, when a hydrophobic water-insoluble crosslinking agent is used, the affinity with the water-insoluble crosslinking agent is increased, the dispersibility of the water-insoluble crosslinking agent is improved, and dents due to poor dispersion can be reduced. . These acetylenic diol compounds can be used alone or in combination of two or more.

  The acetylenic diol compound or the like is preferably a compound having an HLB value of 6 or more represented by the following formula (I) or (II), more preferably 7 or more, still more preferably 8 or more, Most preferably, it is 13 or more. When the HLB value is within the above range, the adherence to the adherend becomes good, which is a preferred embodiment.

R ¹ , R ² , R ³ and R ⁴ in the above formula (I) represent a hydrocarbon group having 1 to 20 carbon atoms and may be a functional group containing a hetero atom. R ¹ , R ² , R ³ and R ⁴ may be the same as or different from each other.

R ¹ , R ² , R ³ and R ⁴ in the above formula (I) may have a linear or branched structure. Among them, R ¹ and R ⁴ are preferably an alkyl group having 2 to 10 carbon atoms, and more preferably an n-butyl group, a sec-butyl group, a tert-butyl group, and an isobutyl group having 4 carbon atoms. R ² and R ³ are preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group or ethyl group having 1 or 2 carbon atoms.

  Specific examples of the compound represented by the above formula (I) include, for example, 7,10-dimethyl-8-hexadecin-7,10-diol, 4,7-dimethyl-5-decyne-4,7-diol, 4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and the like.

  Moreover, when the compound represented by the above formula (I) was blended during the production of the pressure-sensitive adhesive composition of the present invention, the above compound was dispersed or dissolved in various solvents for the purpose of improving blending workability. A thing may be used. Examples of the solvent include 2-ethylhexanol, butyl cellosolve, dipropylene glycol, ethylene glycol, propylene glycol, normal propyl alcohol, and isopropanol. Among these solvents, ethylene glycol and propylene glycol are preferably used from the viewpoint of dispersibility in the emulsion system. Moreover, the solvent content with respect to what disperse | distributed or melt | dissolved the acetylene diol type compound etc. in the solvent at the time of a mixing | blending (100 weight%), when using ethylene glycol as a solvent, is less than 40 weight% (for example, 15-35). % By weight), and when propylene glycol is used as a solvent, it is preferably less than 70% by weight (for example, 20 to 60% by weight).

R ⁵ , R ⁶ , R ⁷ and R ⁸ in the above formula (II) represent a hydrocarbon group having 1 to 20 carbon atoms and may be a functional group containing a hetero atom. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be the same as or different from each other. Moreover, p and q in the said Formula (II) are integers greater than or equal to 0, The sum [p + q] of p and q is 1 or more, 1-20 are preferable, More preferably, it is 1-9. Note that p and q may be the same as or different from each other. p and q are numbers adjusted so that the HLB value is less than 13. When p is 0, [—O— (CH ₂ CH ₂ O) _p H] is a hydroxyl group [—OH], and the same applies to q.

R ⁵ , R ⁶ , R ⁷ and R ⁸ in the above formula (II) may be either linear or branched structures. Among them, R ⁵ and R ⁸ are preferably an alkyl group having 2 to 10 carbon atoms, and particularly an n-butyl group, a sec-butyl group, a tert-butyl group, and an isobutyl group having 4 carbon atoms. R ⁶ and R ⁷ are preferably an alkyl group having 1 to 4 carbon atoms, and particularly preferably a methyl group or ethyl group having 1 or 2 carbon atoms.

  Specific examples of the compound represented by the above formula (II) include, for example, an ethylene oxide adduct of 7,10-dimethyl-8-hexadecin-7,10-diol, 4,7-dimethyl-5-decyne-4, 7-diol ethylene oxide adduct, 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethylene oxide adduct, 3,6-dimethyl-4-octyne-3,6-diol ethylene oxide Examples include adducts. In addition, the average addition mole number of ethylene oxide of ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol is preferably 9 or less.

  When the compound represented by the above formula (II) (such as an ethylene oxide-added acetylenic diol compound) is blended at the time of preparing the pressure-sensitive adhesive composition of the present invention, it is preferable to blend only the above compound without using a solvent. However, for the purpose of improving the blending workability, those obtained by dispersing or dissolving the above compounds in various solvents may be used. Examples of the solvent include 2-ethylhexanol, butyl cellosolve, dipropylene glycol, ethylene glycol, propylene glycol, normal propyl alcohol, and isopropanol. Among these solvents, propylene glycol is preferably used from the viewpoint of dispersibility in the emulsion system. Moreover, the solvent content with respect to what disperse | distributed or melt | dissolved the acetylene diol type compound etc. in the solvent (100 weight%) at the time of a mixing | blending is less than 30 weight% (for example, 1-20, when using ethylene glycol as a solvent). % By weight), and when propylene glycol is used as a solvent, it is preferably less than 70% by weight (for example, 20 to 60% by weight).

  Commercially available products may be used as the compound represented by the above formula (II), and examples thereof include Surfinol 400 series manufactured by Air Products. More specifically, trade names “Surfinol 440” (HLB value: 8), “Surfinol 465” (HLB value: 13), “Surfinol 485” (HLB value: 17) and the like can be mentioned. In addition, trade names “acetylenol E60” (HLB value: 11 to 12), “acetylenol E81” (HLB value: 12.2), “acetylenol E100” (HLB value: 13 to 14), etc., manufactured by Kawaken Fine Chemical Co., Ltd. Can be mentioned. In addition, it is possible to select from the product name “Emulgen” series manufactured by Kao Corporation, the product name “New Coal” series manufactured by Nippon Emulsifier Co., Ltd., and the product name “Neugen” series manufactured by Daiichi Kogyo Seiyaku Co., Ltd. is there. In addition, said acetylene diol type compound etc. can be used individually or in mixture of 2 or more types.

  The compounding amount (use amount) of the nonionic surfactant is 0.01 to 10 parts by weight with respect to 100 parts by weight of the total amount of raw material monomers (total raw material monomers) constituting the acrylic emulsion polymer of the present invention. More preferably, it is 0.1-8 weight part, More preferably, it is 0.5-5 weight part. It is preferable that the amount of the nonionic surfactant is 0.01 parts by weight or more because the ionic liquid can be dispersed uniformly and contamination on the adherend can be reduced. On the other hand, when the blending amount is 10 parts by weight or less, it is preferable because bleeding of the nonionic surfactant to the pressure-sensitive adhesive layer surface is suppressed and contamination of the adherend can be prevented.

[Crosslinking agent]
The pressure-sensitive adhesive composition of the present invention contains a crosslinking agent as an essential component. A pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) with better heat resistance can be obtained by appropriately cross-linking the acrylic emulsion polymer with the cross-linking agent. As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound, and the like are used. Among these, an isocyanate compound and an epoxy compound are particularly preferably used mainly from the viewpoint of obtaining an appropriate cohesive force. These compounds may be used alone or in combination of two or more.

  In particular, in the present invention, it is preferable to use a water-insoluble crosslinking agent as the crosslinking agent. The water-insoluble cross-linking agent is a water-insoluble compound having 2 or more (for example, 2 to 6) functional groups capable of reacting with a carboxyl group in a molecule (in one molecule). is there. The number of functional groups capable of reacting with a carboxyl group in one molecule is preferably 3-5. As the number of functional groups capable of reacting with a carboxyl group in one molecule increases, the pressure-sensitive adhesive composition crosslinks densely (that is, the cross-linked structure of the polymer forming the pressure-sensitive adhesive layer becomes dense). For this reason, it becomes possible to prevent the wetting and spreading of the pressure-sensitive adhesive layer after forming the pressure-sensitive adhesive layer. In addition, since the polymer forming the pressure-sensitive adhesive layer is constrained, the functional group (carboxyl group) in the pressure-sensitive adhesive layer segregates on the surface of the adherend, and the peeling force (adhesive strength) between the pressure-sensitive adhesive layer and the adherend. Can be prevented from rising over time. On the other hand, when the number of functional groups capable of reacting with a carboxyl group in one molecule exceeds 6 and is too large, a gelled product may be formed.

  Although it does not specifically limit as a functional group which can react with the carboxyl group in the water-insoluble crosslinking agent of this invention, For example, an epoxy group, an isocyanate group, a carbodiimide group etc. are mentioned. Among these, an epoxy group is preferable from the viewpoint of reactivity. Furthermore, since the reactivity is high, unreacted substances in the crosslinking reaction hardly remain, which is advantageous for low contamination. Unreacted carboxyl groups in the pressure-sensitive adhesive layer have a peeling force (adhesive strength) with the adherend over time. From the viewpoint that it can be prevented from rising, a glycidylamino group is preferred. That is, as the water-insoluble crosslinking agent of the present invention, an epoxy-based crosslinking agent having an epoxy group is preferable, and among them, a crosslinking agent having a glycidylamino group (glycidylamino-based crosslinking agent) is preferable. When the water-insoluble crosslinking agent of the present invention is an epoxy crosslinking agent (particularly a glycidylamino crosslinking agent), the number of epoxy groups (particularly glycidylamino group) in one molecule is 2 or more (for example, 2 to 6), and 3 to 5 is preferable.

  The water-insoluble crosslinking agent of the present invention is a water-insoluble compound. “Water-insoluble” means that the solubility in 100 parts by weight of water at 25 ° C. (the weight of the compound (crosslinker) soluble in 100 parts by weight of water) is 5 parts by weight or less, preferably 3 It is 2 parts by weight or less, more preferably 2 parts by weight or less. By using a water-insoluble cross-linking agent, the cross-linking agent remaining without cross-linking is unlikely to cause whitening contamination generated on the adherend in a high-humidity environment, and the low-contamination property is improved. In the case of a water-soluble cross-linking agent, in a high humidity environment, the remaining cross-linking agent dissolves in water and is easily transferred to an adherend, and thus easily causes whitening contamination. In addition, the water-insoluble cross-linking agent has a higher contribution to the cross-linking reaction (reaction with a carboxyl group) than the water-soluble cross-linking agent, and has a high effect of preventing the peeling force (adhesive force) from increasing with time. Furthermore, since the water-insoluble cross-linking agent has high reactivity of the cross-linking reaction, the cross-linking reaction proceeds promptly by aging, and the peeling force (adhesive strength) from the adherend is increased by the unreacted carboxyl group in the pressure-sensitive adhesive layer. It is possible to prevent an increase over time.

  In addition, the solubility with respect to the water of the said crosslinking agent can be measured as follows, for example.

[Method of measuring solubility in water]
The same weight of water (25 ° C.) and the crosslinking agent are mixed using a stirrer at a rotation speed of 300 rpm for 10 minutes, and separated into an aqueous phase and an oil phase by centrifugation. Next, the aqueous phase is collected and dried at 120 ° C. for 1 hour, and the nonvolatile content in the aqueous phase (parts by weight of nonvolatile components relative to 100 parts by weight of water) is determined from the loss on drying.

  Specifically, as the water-insoluble crosslinking agent of the present invention, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (for example, trade name “TETRAD-C” manufactured by Mitsubishi Gas Chemical Co., Ltd.) Etc.] [Solubility of 2 parts by weight or less with respect to 100 parts by weight of water at 25 ° C.] 1,3-bis (N, N-diglycidylaminomethyl) benzene (for example, trade name “TETRAD-” manufactured by Mitsubishi Gas Chemical Co., Ltd.) X ”etc.) [glycidylamino-based cross-linking agent such as solubility in 100 parts by weight of water at 25 ° C. of 2 parts by weight or less]; Tris (2,3-epoxypropyl) isocyclicate (for example, product name“ Nissan Chemical Co., Ltd., trade name “ Other epoxy-based cross-linking agents such as “TEPIC-G” and the like] [solubility of 2 parts by weight or less with respect to 100 parts by weight of water at 25 ° C.] are exemplified.

  The blending amount of the crosslinking agent (water-insoluble crosslinking agent) of the present invention (content in the pressure-sensitive adhesive composition of the present invention) is a carboxyl group-containing unsaturated monomer used as a raw material monomer for the acrylic emulsion polymer of the present invention. It is preferable that the amount of the functional group capable of reacting with the carboxyl group of the water-insoluble crosslinking agent of the present invention is 0.2 to 1.3 mol per mol of the carboxyl group. That is, with respect to “the total number of carboxyl groups of all carboxyl group-containing unsaturated monomers used as a raw material monomer of the acrylic emulsion polymer of the present invention”, “the carboxyl groups of all the water-insoluble crosslinking agents of the present invention and It is preferable that the ratio [functional group / carboxyl group capable of reacting with carboxyl group] (molar ratio) of “the total number of moles of functional groups capable of reacting” is 0.2 to 1.3, more preferably 0.3 to 1.1, more preferably 0.5 to 1.0. By setting [functional group / carboxyl group capable of reacting with carboxyl group] to 0.2 or more, unreacted carboxyl group in the pressure-sensitive adhesive layer is reduced, resulting from the interaction between the carboxyl group and the adherend. It is preferable because an increase in peel strength (adhesive strength) over time can be effectively prevented. Moreover, by setting it as 1.3 or less, the unreacted water-insoluble cross-linking agent in the pressure-sensitive adhesive layer can be reduced, appearance defects due to the water-insoluble cross-linking agent can be suppressed, and the appearance characteristics can be improved. preferable.

  In particular, when the water-insoluble crosslinking agent of the present invention is an epoxy crosslinking agent, the [epoxy group / carboxyl group] (molar ratio) is preferably 0.2 to 1.3, and more preferably It is 0.3-1.1, More preferably, it is 0.5-1.0. Furthermore, when the water-insoluble crosslinking agent of the present invention is a glycidylamino crosslinking agent, it is preferable that [glycidylamino group / carboxyl group] (molar ratio) satisfy the above range.

For example, 4 g of a water-insoluble crosslinking agent having a functional group equivalent to a carboxyl group of 110 (g / eq) is added to the water-dispersed acrylic pressure-sensitive adhesive composition (pressure-sensitive adhesive composition). In the case of (mixing), the number of moles of the functional group that can react with the carboxyl group of the water-insoluble crosslinking agent can be calculated as follows, for example.
Number of moles of functional group capable of reacting with carboxyl group of water-insoluble crosslinking agent = [blending amount of water-insoluble crosslinking agent (blending amount)] / [functional group equivalent] = 4/110
For example, when 4 g of an epoxy-based crosslinking agent having an epoxy equivalent of 110 (g / eq) is added (mixed) as a water-insoluble crosslinking agent, the number of moles of epoxy groups possessed by the epoxy-based crosslinking agent is, for example, as follows: Can be calculated.
Number of moles of epoxy group possessed by epoxy crosslinking agent = [blending amount of epoxy crosslinking agent (blending amount)] / [epoxy equivalent] = 4/110

[Ionic compounds]
The pressure-sensitive adhesive composition of the present invention contains an ionic compound as an essential component. The ionic compound is not particularly limited. For example, the ionic compound preferably contains an anion containing a fluorine atom, an anion containing a nitrogen atom, or an anion having a sulfonyl group, and more preferably an ion. Liquid and / or alkali metal salts. By containing these ionic compounds, excellent antistatic properties can be imparted.

  By using the ionic liquid as an antistatic agent as the ionic compound, an adhesive layer having a high antistatic effect can be obtained without impairing adhesive properties. Although details of the reason why excellent antistatic properties can be obtained by using an ionic liquid are not clear, it is considered that the ionic liquid is in a liquid state, so that molecular movement is easy and excellent antistatic ability can be obtained. . In particular, when antistatic is applied to the adherend, it is considered that the ionic liquid is transferred onto the adherend in a very small amount, thereby achieving excellent antistatic peeling on the adherend.

  In addition, since the ionic liquid is liquid at room temperature (25 ° C.), it can be easily added and dispersed or dissolved in the pressure-sensitive adhesive as compared with a solid salt. Further, since the ionic liquid has no vapor pressure (nonvolatile), it has a characteristic that the antistatic property is continuously obtained without disappearing with time. The ionic liquid refers to a molten salt (ionic compound) that is liquid at room temperature (25 ° C.).

  As said ionic liquid, what consists of an organic cation component represented by the following general formula (A)-(E) and an anion component is used preferably. An ionic liquid having these cations provides a further excellent antistatic ability.

R _a in the formula (A) represents a hydrocarbon group having 4 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, and R _b and R _c May be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. However, when the nitrogen atom contains a double bond, there is no R _c .

R _d in the formula (B) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, R _e , R _f And R _g may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom.

R _h in the formula (C) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, R _i , R _j , And R _k may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom.

Z in the formula (D) represents a nitrogen, sulfur, or phosphorus atom, and R ₁ , R _m , R _n , and R _o are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms. In addition, a functional group in which a part of the hydrocarbon group is substituted with a hetero atom may be used. However, when Z is a sulfur atom, there is no _Ro .

R _P in the formula (E) represents a hydrocarbon group having 1 to 18 carbon atoms, a part of the hydrocarbon group may be substituted by a functional group with a heteroatom.

  Examples of the cation represented by the formula (A) include a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a cation having a pyrroline skeleton, a cation having a pyrrole skeleton, and a morpholinium cation.

  Specific examples include, for example, 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl. -3-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidi Cation, 1-methyl-1-butylpyrrolidinium cation, 1-methyl-1-pentylpyrrolidinium cation, 1-methyl-1-hexylpyrrolidinium cation, 1-methyl-1-heptylpyrrolidinium Cation, 1-ethyl-1-propylpyrrolidini Cation, 1-ethyl-1-butylpyrrolidinium cation, 1-ethyl-1-pentylpyrrolidinium cation, 1-ethyl-1-hexylpyrrolidinium cation, 1-ethyl-1-heptylpyrrolidinium Cation, 1,1-dipropylpyrrolidinium cation, 1-propyl-1-butylpyrrolidinium cation, 1,1-dibutylpyrrolidinium cation, pyrrolidinium-2-one cation, 1-propylpiperidinium cation, 1-pentylpiperidinium cation, 1,1-dimethylpiperidinium cation, 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-propylpiperidinium cation, 1-methyl-1-butylpi Peridinium cation, 1-methyl-1-pentylpiperidinium cation 1-methyl-1-hexylpiperidinium cation, 1-methyl-1-heptylpiperidinium cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1 -Ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation, 1-ethyl-1-heptylpiperidinium cation, 1,1-dipropylpiperidinium cation, 1-propyl -1-butylpiperidinium cation, 1,1-dibutylpiperidinium cation, 2-methyl-1-pyrroline cation, 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole Cations, N-ethyl-N-methylmorpholinium cations, etc. It is done.

  Examples of the cation represented by the formula (B) include an imidazolium cation, a tetrahydropyrimidinium cation, and a dihydropyrimidinium cation.

  Specific examples include, for example, 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, and 1-helium. Xyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazole Cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3 -Dimethylimidazolium cation, 1- (2-metho (Ciethyl) -3-methylimidazolium cation, 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium Cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium Cation, 1,3-dimethyl-1,4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium Cation, 1,2,3-trimethyl-1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium kathi Emissions, such as 1,2,3,4-tetramethyl-1,6-dihydropyrimidinium cation.

  Examples of the cation represented by the formula (C) include a pyrazolium cation and a pyrazolinium cation.

  Specific examples include, for example, 1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation, 1-ethyl-2,3,5-trimethylpyrazolium cation. 1-propyl-2,3,5-trimethylpyrazolium cation, 1-butyl-2,3,5-trimethylpyrazolium cation, 1-ethyl-2,3,5-trimethylpyrazolinium cation, 1 -Propyl-2,3,5-trimethylpyrazolinium cation, 1-butyl-2,3,5-trimethylpyrazolinium cation and the like.

  Examples of the cation represented by the formula (D) include a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraalkylphosphonium cation, and a part of the alkyl group is an alkenyl group, an alkoxyl group, a hydroxyl group, a cyano group, Examples include those substituted with an epoxy group.

  Specific examples include, for example, tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptylammonium cation, triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, glycidyltrimethylammonium cation, trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutyl Ethylsulfonium Kachi , Dimethyldecylsulfonium cation, tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium cation, tetrahexylphosphonium cation, tetraoctylphosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, diallyldimethylammonium cation And tributyl- (2-methoxyethyl) phosphonium cation. Among them, asymmetric such as triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, etc. Tetraalkylammonium cation, trialkylsulfonium cation, tetraalkylphosphonium cation, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N, N -Dimethyl-N-ethyl-N-propyla Monium cation, N, N-dimethyl-N-ethyl-N-butylammonium cation, N, N-dimethyl-N-ethyl-N-pentylammonium cation, N, N-dimethyl-N-ethyl-N-hexylammonium cation N, N-dimethyl-N-ethyl-N-heptylammonium cation, N, N-dimethyl-N-ethyl-N-nonylammonium cation, N, N-dimethyl-N, N-dipropylammonium cation, N, N-diethyl-N-propyl-N-butylammonium cation, N, N-dimethyl-N-propyl-N-pentylammonium cation, N, N-dimethyl-N-propyl-N-hexylammonium cation, N, N- Dimethyl-N-propyl-N-heptylammonium cation, N, N-di Tyl-N-butyl-N-hexylammonium cation, N, N-diethyl-N-butyl-N-heptylammonium cation, N, N-dimethyl-N-pentyl-N-hexylammonium cation, N, N-dimethyl- N, N-dihexylammonium cation, trimethylheptylammonium cation, N, N-diethyl-N-methyl-N-propylammonium cation, N, N-diethyl-N-methyl-N-pentylammonium cation, N, N-diethyl -N-methyl-N-heptylammonium cation, N, N-diethyl-N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, N, N- Dipropyl-N-methyl-N-ethylammonium cation, N, N-dipropyl-N-methyl-N-pentylammonium cation, N, N-dipropyl-N-butyl-N-hexylammonium cation, N, N-dipropyl- N, N-dihexylammonium cation, N, N-dibutyl-N-methyl-N-pentylammonium cation, N, N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation, N-methyl- N-ethyl-N-propyl-N-pentylammonium cation is preferably used.

Examples of the cation represented by the formula (E) include a sulfonium cation. Further, the formula Specific examples of R _P in (E) is a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, An octadecyl group etc. are mentioned.

The ionic liquid preferably contains at least one cation selected from the group consisting of cations represented by the following formulas (a) to (d). These cations are included in the formulas (A) and (B).

[R ₁ in Formula (a) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₂ represents hydrogen or a hydrocarbon group having 1 to 7 carbon atoms. ]
[R ₃ in Formula (b) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₄ represents hydrogen or a hydrocarbon group having 1 to 7 carbon atoms. ]
[R ₅ in Formula (c) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₆ represents hydrogen or a hydrocarbon group having 1 to 7 carbon atoms. ]
[R ₇ in Formula (d) represents hydrogen or a hydrocarbon group having 1 to 3 carbon atoms, and R ₈ represents hydrogen or a hydrocarbon group having 1 to 7 carbon atoms. ]

On the other hand, the anion component is not particularly limited as long as it satisfies that it becomes an ionic liquid. For example, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF _{6 are used.} ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , Li (C ₃ F ₇ SO ₂ ) ₂ N, Li ( C ₄ F ₉ SO ₂ ) ₂ N, (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) _n ⁻ , (CN) ₂ N ⁻ , ^{_{C 4 F 9 SO 3 -,}} (C 2 F 5 SO 2) 2 N -, C 3 F 7 COO -, (CF 3 SO 2) (CF 3 CO) N -, C 9 H 19 COO -, (CH _{^{3) 2 PO 4 -, (}} C 2 H 5) 2 _{^{O 4 -, C 2 H 5}} OSO 3 -, C 6 H 13 OSO 3 -, C 8 H 17 OSO 3 -, CH 3 (OC 2 H 4) 2 OSO 3 -, C 6 H 4 (CH 3) SO _{^{3 -, (C 2 F 5}} ) 3 PF 3 -, CH 3 CH (OH) COO -, _{and, (FSO 2) 2} N ^- and the like are used. Among these, an anionic component containing a fluorine atom is preferably used because an ionic compound having a low melting point is obtained. In addition, anionic components having a nitrogen atom are preferably used because they impart hydrophobicity and do not dissociate even when added to a water-dispersed pressure-sensitive adhesive, and the generation of aggregates is small. Furthermore, an anionic component having a sulfonyl group is preferably used from the viewpoint of excellent stability in water, electrical conductivity, or thermal stability.

Moreover, as the anion component, an anion represented by the following formula (F) can also be used.

Specific examples of the ionic liquid used in the present invention are appropriately selected from a combination of the cation component and the anion component. For example, 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium hexafluorophosphate, 1-butyl -3-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide, 1-butyl-3-methylpyridinium bis (pentafluoroethane Sulfonyl) imide, 1-hexylpyridinium tetrafluoroborate, 1,1-dimethylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-ethylpyrrolidinium bis ( Trifluoromethanesulfonyl) imide, 1-methyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-pentyl Pyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-hexylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-heptylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1 -Ethyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-pentylpyrrolidinium bis (trifluorome Sulfonyl) imide, 1-ethyl-1-hexylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-heptylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1,1-dipropylpyrrole Dinium bis (triple olomethanesulfonyl) imide, 1-propyl-1-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1,1-dibutylpyrrolidinium bis (triple methanesulfonyl) imide, 1-propylpi Peridinium bis (trifluoromethanesulfonyl) imide, 1-pentylbiberidinium bis (trifluoromethanesulfonyl) imide, 1,1-dimethylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-ethylpiperidi Niu Mubis (trifluoromethanesulfonyl) imide, 1-methyl-1-propylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-butylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1- Pentylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-hexylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-heptylpiperidinium bis (trifluoromethanesulfonyl) imide, 1 -Ethyl-1-propylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-butylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-pentylpiperidinium bis (trif Olomethanesulfonyl) imide, 1-ethyl-1-hexylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-heptylpiperidinium bis (trifluoromethanesulfonyl) imide, 1,1-dipropyl Piperidinium bis (trifluoromethanesulfonyl) imide, 1-propyl-1-butylpiperidiniumpis (trifluoromethanesulfonyl) imide, 1,1-dibutylpiperidinium bis (trifluoromethanesulfonyl) imide, 1,1-dimethyl Pyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-ethylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-propylpyrrolidinium bis (pentafluoroethanesulfonyl) imi 1-methyl-1-butylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-pentylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-hexylpyrrolidinium Bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-heptylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-propylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1- Ethyl-1-butylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-pentylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-hexylpyrrolidinium bis (penta Fluoroethanesulfonyl) imi 1-ethyl-1-heptylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1,1-dipropylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-propyl-1-butylpyrrolidinium Bis (pentafluoroethanesulfonyl) imide, 1,1-dibutylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-propylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-pentylpiperidinium bis (venta) Fluoroethanesulfonyl) imide, 1,1-dimethylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-ethylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-propylpi Peridinium (Pentafluoroethanesulfonyl) imide, 1-methyl-1-butylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-pentylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl -1-hexylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-heptylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-propylpiperidinium bis (penta Fluoroethanesulfonyl) imide, 1-ethyl-1-butylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-pentylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1- Hexyl piperidinium Bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-heptylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1,1-dipropylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-propyl -1-butylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1,1-dibutylpiperidinium bis (pentafluoroethanesulfonyl) imide, 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2- Phenylindole tetrafluoroborate, 1,2-dimethylindole tetrafluoroborate, 1-ethylcarbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium Tate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium heptafluorobutyrate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazole 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium bis (pentafluoroethanesulfonyl) 1-ethyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide Imido, 1-ethyl-3-methylimidazolium tris (trifluoromethanesulfonyl) methide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-3-methylimidazolium heptafluorobutyrate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazole 1-hexyl-3-methylimidazolium chloride, 1-hexyl 3-perfluorobutanesulfonate, 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-hexyl-3-methylimidazolium bromide 3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium Lafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-dimethyl-3-propylimidazolium bis (trifluoromethanesulfonyl) Imido, 1-methylpyrazolium tetrafluoroborate, 2-methylpyrazolium tetrafluoroporate, 1-ethyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide, 1-propyl-2, 3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide, 1-butyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-2,3,5-trimethylpyra Zorium bis (Pentaful Loethanesulfonyl) imide, 1-propyl-2,3,5-trimethylpyrazolium bis (pentafluoroethanesulfonyl) imide, 1-butyl-2,3,5-trimethylpyrazolium bis (pentafluoroethanesulfonyl) Imido, 1-ethyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) trifluoroacetamide, 1-propyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) trifluoroacetamide, 1-butyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) trifluoroacetamide, 1-ethyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) imide, 1-propyl- 2,3,5-trimethyl Rupyrazolinium bis (trifluoromethanesulfonyl) imide, 1-butyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-2,3,5-trimethylpyrazolinium bis ( Pentafluoroethanesulfonyl) imide, 1-propyl-2,3,5-trimethylpyrazolinium bis (pentafluoroethanesulfonyl) imide, 1-butyl-2,3,5-trimethylpyrazolinium bis (pentafluoroethanesulfonyl) ) Imido, 1-ethyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) trifluoroacetamide, 1-propyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) trifluoroacetamide 1-Buchi -2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) trifluoroacetamide, tetrapentylammonium trifluoromethanesulfonate, tetrapentylammonium bis (trifluoromethanesulfonyl) imide, tetrahexylammonium trifluoromethanesulfonate, tetrahexylammonium bis (Trifluoromethanesulfonyl) imide, tetrahebutylammonium trifluoromethanesulfonate, tetraheptylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis (trifluoromethanesulfonyl) imi , Diallyldimethylammonium bis (pentafluoroethanesulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-N-methyl-N- (2 -Methoxyethyl) ammo

Nium trifluoromethanesulfonate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-Nmethyl-N- (2-methoxyethyl) ammonium Bis (pentafluoroethanesulfonyl) imide, glycidyltrimethylammonium trifluoromethanesulfonate, glycidyltrimethylammonium bis (trifluoromethanesulfonyl) imide, glycidyltrimethylammonium bis (pentafluoroethanesulfonyl) imide, tetraoctylphosphonium trifluoromethanesulfonate, tetraoctylphosphonium bis (Trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-propylammonium bis ( Trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-butylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl -N-ethyl-N-nonylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N-dipropylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N- Butylammonium Mubis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-hexylammonium bis (trifluoromethanesulfonyl) Imido, N, N-dimethyl-N-propyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N- Dimethyl-N-butyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-pentyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N Dihexylammonium bis (trifluoromethanesulfonyl) imide, trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N -Methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-propyl-N-pentyl Ammonium bis (trifluoromethanesulfonyl) imide, triethylpropylammonium bis (trifluoromethanesulfonyl) imide, triethylpentylammonium bis (trifluoromethanes) Phonyl) imide, triethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl-N-ethylammonium bis (trifluoromedansulfonyl) imide, N, N-dipropyl-N-methyl-N- Pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) ) Imide, N, N-dibutyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl-N-hexylammonium bis (trifluoromethanesulfonate) ) Imide, trioctylmethylammonium bis (trifluoromethanesulfonyl) imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, 1-butylpyridinium (trifluoromethanesulfonyl) tri Fluoroacetamide, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-ethyl-3-methylimidazolium (trifluoromethanesulfonyl) trifluoroacetamide, N-ethyl-N-methylmorpholinium thiocyanate, 4-ethyl-4-methylmorpholinium methyl carbonate, 1-ethyl-3-methylimidazolium thiocyanate, 1-butyl-3-methylimidazolium thiocyanate 1-ethyl-3-methylimidazolium tetracyanoborate, 1-ethyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate, 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) ) Imide, triethylsulfonium bis (trifluoromethylsulfonyl) imide and the like.

  A commercially available ionic liquid as described above may be used, but it can also be synthesized as follows. The method of synthesizing the ionic liquid is not particularly limited as long as the target ionic liquid can be obtained. In general, however, it is described in the document “Ionic liquids—the forefront and future of development” [CMC Publishing Co., Ltd.]. As described, a halide method, a hydroxide method, an acid ester method, a complex formation method, a neutralization method, and the like are used.

  The synthesis method of the halide method, hydroxide method, acid ester method, complex formation method, and neutralization method will be described below using a nitrogen-containing onium salt as an example. Other sulfur-containing onium salts, phosphorus-containing onium salts, etc. This ionic liquid can also be obtained by the same method.

The halide method is a method carried out by reactions as shown in the following formulas (1) to (3). First, a tertiary amine and an alkyl halide are reacted to obtain a halide. (Reaction formula (1), chlorine, bromine and iodine are used as the halogen) Acid (HA) or salt (MA, M having the anionic structure (A ⁻ ) of the ionic liquid intended for the obtained halide A target ionic liquid (R ₄ NA) is obtained by reacting with a target anion such as ammonium, lithium, sodium, potassium and the like to form a salt.

The hydroxide method is a method performed by reactions as shown in (4) to (8). First, halide (R ₄ NX) is subjected to ion exchange membrane electrolysis (reaction formula (4)), OH type ion exchange resin method (reaction formula (5)) or reaction with silver oxide (Ag ₂ O) (reaction formula ( 6)) to obtain the hydroxide (R ₄ NOH). (Chlorine, bromine and iodine are used as the halogen) The obtained hydroxide is converted into the target ionic liquid (R ₄ NA) using the reactions of the reaction formulas (7) to (8) in the same manner as the halogenation method. ) Is obtained.

The acid ester method is a method performed by reactions as shown in (9) to (11). First, a tertiary amine (R ₃ N) is reacted with an acid ester to obtain an acid ester product. (Reaction formula (9), as the acid ester, an ester of an inorganic acid such as sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid or carbonic acid, or an organic acid such as methanesulfonic acid, methylphosphonic acid or formic acid) The target acid liquid (R ₄ NA) is obtained from the obtained acid ester product using the reactions of the reaction formulas (10) to (11) in the same manner as in the halogenation method. Further, by using methyl trifluoromethanesulfonate, methyl trifluoroacetate or the like as the acid ester, an ionic liquid can be obtained directly.

The complex formation method is a method performed by reactions as shown in (12) to (15). First, a quaternary ammonium halide (R ₄ NX), a quaternary ammonium hydroxide (R ₄ NOH), a quaternary ammonium carbonate ester (R ₄ NOCO ₂ CH ₃ ) or the like is added to hydrogen fluoride (HF) or Reaction with ammonium fluoride (NH ₄ F) gives a quaternary ammonium fluoride salt. (Reaction formulas (12) to (14)) The obtained quaternary ammonium fluoride salt is subjected to a complex formation reaction with fluorides such as BF ₃ , AlF ₃ , PF ₅ , ASF ₅ , SbF ₅ , NbF ₅ , and TaF _5. An ionic liquid can be obtained. (Reaction Formula (15))

The neutralization method is a method performed by a reaction as shown in (16). Tertiary amine and HBF ₄ , HPF ₆ , CH ₃ COOH, CF ₃ COOH, CF ₃ SO ₃ H, (CF ₃ SO ₂ ) ₂ NH, (CF ₃ SO ₂ ) ₃ CH, (C ₂ F ₅ SO ₂ ) ₂ It can be obtained by reacting with an organic acid such as NH.

  R in the above formulas (1) to (16) represents hydrogen or a hydrocarbon group having 1 to 20 carbon atoms, and a part of the hydrocarbon group may be substituted with a hetero atom or a functional group. good.

Since the alkali metal salt has high ion dissociation properties, it is preferable in that it exhibits excellent antistatic ability even with a small amount of addition. Examples of the alkali metal salt include a cation composed of Li ⁺ , Na ⁺ , K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN. _{^{-, ClO 4 -, NO 3}} -, CH 3 COO -, C 9 H 19 COO -, CF 3 COO -, C 3 F 7 COO -, CH 3 SO 3 -, CF 3 SO 3 -, C 4 F 9 SO ₃ ⁻ , C ₂ H ₅ OSO ₃ ⁻ , C ₆ H ₁₃ OSO ₃ ⁻ , C ₈ H ₁₇ OSO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , ^{_{F (HF) n -, (}} CN) _{^{N -, (CF 3 SO 2}} ) (CF 3 CO) N -, (CH 3) 2 PO 4 -, (C 2 H 5) 2 PO 4 -, CH 3 (OC 2 H 4) 2 OSO 3 -, An alkali metal composed of an anion consisting of C ₆ H ₄ (CH ₃ ) SO ₃ ⁻ , (C ₂ F ₅ ) ₃ PF ₃ ⁻ , CH ₃ CH (OH) COO ⁻ , and (FSO ₂ ) ₂ N ^−. A salt is preferably used. Among these, an anionic component containing a fluorine atom is preferably used because an ionic compound having a low melting point is obtained. In addition, anionic components having a nitrogen atom are preferably used because they impart hydrophobicity and do not dissociate even when added to a water-dispersed pressure-sensitive adhesive, and the generation of aggregates is small. Furthermore, an anionic component having a sulfonyl group is preferably used from the viewpoint of excellent stability in water, electrical conductivity, or thermal stability. More _{preferably, LiBr, LiI, LiBF 4,} LiPF 6, LiSCN, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, Li (C 2 F 5 SO 2) 2 N, Li (FSO 2 ) ₂ N, lithium salts such as Li (CF ₃ SO ₂ ) ₃ C, more preferably LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li ( C ₃ F ₇ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO ₂ ) ₂ N, Li (FSO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C are used. These alkali metal salts may be used alone or in combination of two or more.

  The content of the ionic compound (ionic liquid, alkali metal salt, etc.) is preferably 0.5 to 3 parts by weight, more preferably 0 with respect to 100 parts by weight (solid content) of the acrylic emulsion polymer. .6 to 2 parts by weight, most preferably 0.7 to 1.5 parts by weight. It is preferable for it to be in the above-mentioned range since it is easy to achieve both antistatic properties and low contamination.

[Ether group-containing polysiloxane]
The water-dispersed acrylic pressure-sensitive adhesive composition may further contain an ether group-containing polysiloxane (alkylene oxide-containing polysiloxane). By containing the ether group-containing polysiloxane (alkylene oxide-containing polysiloxane), more excellent antistatic properties can be exhibited. The details of the mechanism by which antistatic properties are manifested are not clear, but the ether group has a high affinity for moisture in the air, so the charge transfer to the air is easy to occur. Therefore, it is presumed that excellent antistatic properties are exhibited because the electric charge generated at the time of peeling is easily transferred to the air efficiently. In addition, since the silicone (polysiloxane) skeleton has a high surface adsorptivity even with a small amount due to its low surface tension, a small amount can be uniformly transferred to the adherend surface when the adhesive sheet is peeled off from the adherend (protected body). In addition, the movement of charges generated on the surface of the adherend can be efficiently caused, and excellent antistatic properties are exhibited.

  The ether group-containing polysiloxane (alkylene oxide-containing polysiloxane) is preferably constituted (contained) from an ethylene oxide (EO) group. Further, a propylene oxide (PO) group may be included as an alkylene oxide group other than the EO group. In this case, the molar content of the PO is 100% of the total molar content of the EO and PO. On the other hand, it is preferably 50% or less. When the polysiloxane is composed of the EO group (including as a constituent component), it is possible to impart more excellent peeling antistatic properties, which is a preferred embodiment.

  The ether group-containing polysiloxane (sometimes simply referred to as polysiloxane) preferably has an HLB (Hydrophile-Lipophile-Blance) value of 4 to 12, more preferably 5 to 11, Especially preferably, it is 6-10. When the HLB value is within the above range, not only can the antistatic property be imparted, but also the contamination property to the adherend becomes good, which is a preferred embodiment.

  Specific examples of the polysiloxane include trade names of KF-352A, KF-353, KF-615, KF-6012, KF-351A, KF-353, KF-945, KF-6011, KF- 889, KF-6004 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), FZ-2122, FZ-2164, FZ-7001, SH8400, SH8700, SF8410, SF8422 (above, manufactured by Toray Dow Corning), TSF-4440, TSF -4445, TSF-4252, TSF-4460 (made by Momentive Performance Materials), BYK-333, BYK-377, BYK-UV3500, BYK-UV3570 (made by Big Chemie Japan), etc. are mentioned. These compounds may be used alone or in combination of two or more.

Among the polysiloxanes, those represented by the following formulas are preferable because the antistatic property is more easily expressed in that the ionic compound can be bound to the side chain and adsorbed to the interface.

(Wherein R ₁ is a monovalent organic group, R ₂ , R ₃ and R ₄ are alkylene groups, or R ₅ is a hydroxyl group or an organic group, m and n are integers from 0 to 1000, provided that m, n Are not 0 at the same time, and a and b are integers of 0 to 100, provided that a and b are not 0 at the same time.)

  More preferably, the polysiloxane has a hydroxyl group at the end of the side chain of the polyoxyalkylene (polyether). Use of the polysiloxane is effective because it can exhibit antistatic properties to an adherend (protected body).

As the polysiloxane, specifically, R _{1 in} the formula is an alkyl group such as a methyl group, an ethyl group or a propyl group, an aryl group such as a phenyl group or a tolyl group, or an alkyl group such as a benzyl group or a phenethyl group. And a monovalent organic group exemplified by a group, each of which may have a substituent such as a hydroxyl group. R ₂ , R ₃ and R ₄ may be an alkylene group having 1 to 8 carbon atoms such as a methylene group, an ethylene group or a propylene group. Here, R ₃ and R ₄ are different alkylene groups, and R ₂ may be the same as or different from R ₃ or R ₄ . One of R ₃ and R ₄ is an ethylene group or a propylene group in order to increase the concentration of an antistatic agent (such as an ionic compound) that can be dissolved in the polyoxyalkylene (polyether) side chain. It is preferable. R ₅ may be an alkyl group such as a methyl group, an ethyl group or a propyl group, or a monovalent organic group exemplified by an acyl group such as an acetyl group or a propionyl group, each having a substituent such as a hydroxyl group. It may be. These compounds may be used alone or in combination of two or more. Moreover, you may have reactive substituents, such as a (meth) acryloyl group, an allyl group, and a hydroxyl group, in a molecule | numerator. Among the polysiloxanes having a polyoxyalkylene (polyether) side chain, the polysiloxane having a hydroxyl group-terminated polyoxyalkylene (polyether) side chain is presumed to have a good balance of compatibility. Therefore, it is preferable.

  Moreover, as a compounding quantity of the said polysiloxane, it is preferable to contain 0.2-1 weight part with respect to 100 weight part of the said acrylic emulsion type polymer (solid content), 0.25-0.8 weight part Is more preferable, and 0.3 to 0.6 parts by weight is still more preferable. When the amount is less than 0.2 parts by weight, it is difficult to obtain antistatic properties, and when the amount exceeds 1 part by weight, contamination of the adherend may increase.

[Re-peeling water-dispersed acrylic pressure-sensitive adhesive composition]
As described above, the pressure-sensitive adhesive composition of the present invention contains the acrylic emulsion polymer of the present invention, a crosslinking agent, an ionic compound, and a nonionic surfactant having a specific HLB value as essential components. Furthermore, you may contain other various additives as needed. For example, as long as it does not affect the contamination property, various additives such as pigments, fillers, leveling agents, dispersants, plasticizers, stabilizers, antioxidants, UV absorbers, UV stabilizers, anti-aging agents Agents, preservatives, antifoaming agents and the like.

  The pressure-sensitive adhesive composition of the present invention includes a so-called non-reactive component other than a reactive (polymerizable) component that is incorporated into a polymer that forms a pressure-sensitive adhesive layer by reacting (polymerizing) with a raw material monomer of an acrylic emulsion polymer. It is preferable that a reactive (non-polymerizable) component (however, excluding components such as water that volatilizes by drying and does not remain in the pressure-sensitive adhesive layer) is not substantially contained. If non-reactive components remain in the pressure-sensitive adhesive layer, these components may be transferred to the adherend and cause whitening contamination. “Substantially free” means that it is not actively added unless it is inevitably mixed. Specifically, the pressure-sensitive adhesive composition (nonvolatile content) of these non-reactive components is used. ) Is preferably less than 1% by weight, more preferably less than 0.1% by weight, still more preferably less than 0.005% by weight.

  Examples of the non-reactive component include a component that bleeds to the surface of the pressure-sensitive adhesive layer such as a phosphate ester compound used in JP-A-2006-45412 to impart releasability. Non-reactive emulsifiers such as sodium lauryl sulfate and ammonium lauryl sulfate are also included.

  As a method for mixing the pressure-sensitive adhesive composition of the present invention, a known and usual method for mixing emulsions can be used, and is not particularly limited. For example, stirring using a stirrer is preferable. Although stirring conditions are not specifically limited, For example, as for temperature, 10-50 degreeC is preferable, More preferably, it is 20-35 degreeC. The stirring time is preferably 5 to 30 minutes, more preferably 10 to 20 minutes. The stirring rotation speed is preferably 10 to 3000 rpm, more preferably 30 to 1000 rpm.

[Adhesive layer, adhesive sheet]
The pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) of the present invention is formed from the pressure-sensitive adhesive composition. The formation method of an adhesive layer is not specifically limited, The formation method of a well-known and usual adhesive layer can be used. The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition on a substrate or a release film (release liner, separator) and then drying. In the case where the pressure-sensitive adhesive layer is formed on a release (release) film, the pressure-sensitive adhesive layer is bonded to a substrate and transferred.

  In forming the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet), the drying temperature is usually about 80 to 170 ° C., preferably 80 to 160 ° C., and a drying time of about 0.5 to 30 minutes, preferably 1 to 10 minutes. Further, the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) is prepared by curing (aging) at room temperature to about 50 ° C. for 1 day to 1 week.

  Various methods are used for the application | coating process of the said adhesive composition. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  Moreover, in the said application | coating process, the application quantity is controlled so that the adhesive layer formed may become predetermined | prescribed thickness (thickness after drying). The thickness of the pressure-sensitive adhesive layer (thickness after drying) is usually about 1 to 100 μm, preferably 5 to 50 μm, more preferably 10 to 40 μm.

  The solvent-insoluble content (gel fraction) of the pressure-sensitive adhesive layer is preferably 90% (% by weight) or more, more preferably 95% by weight or more. Within the above range, good removability is obtained, which is a preferred embodiment.

  In addition, as a measuring method of the solvent insoluble part (gel fraction) of the said adhesive layer, it can measure with the following method, for example.

About 0.1 g of the crosslinked acrylic pressure-sensitive adhesive film was collected, wrapped in a porous tetrafluoroethylene sheet (trade name “NTF1122”, manufactured by Nitto Denko Corporation) with an average pore size of 0.2 μm, and then tied with a string. The weight at that time was measured, and the weight was defined as the weight before immersion. The weight before immersion is the total weight of the crosslinked film (collected above), the tetrafluoroethylene sheet, and the kite string. Further, the total weight of the tetrafluoroethylene sheet and the kite string was also measured, and this weight was used as the wrapping weight.
Next, the crosslinked film wrapped with a tetrafluoroethylene sheet and tied with a kite string (referred to as “sample”) was placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23 ° C. for 7 days. Then, the sample (after ethyl acetate treatment) is taken out from the container, transferred to an aluminum cup, dried in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, the weight is measured, and the weight is immersed. It was set as the rear weight. And the solvent insoluble content was computed from the following formula.
Solvent insoluble content (% by weight) = (d−e) / (f−e) × 100
(In the above formula, d is the weight after immersion, e is the weight of the bag, and f is the weight before immersion.)

  Further, the glass transition temperature (Tg) of the acrylic emulsion polymer (after crosslinking) forming the pressure-sensitive adhesive layer is preferably −70 to −10 ° C., more preferably −70 to −20 ° C., and further preferably − It is 70--40 degreeC, Most preferably, it is -70--50 degreeC. When the glass transition temperature exceeds −10 ° C., the adhesive strength is insufficient, and floating or peeling may occur during processing. Moreover, if it is less than -70 degreeC, there exists a possibility that it may peel heavily in a higher peeling speed (tensile speed) area | region, and work efficiency may fall. The glass transition temperature of the polymer forming the adhesive layer (after crosslinking) can also be adjusted, for example, by the monomer composition when preparing the acrylic emulsion polymer of the present invention.

  Examples of the constituent material of the release film include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. However, a plastic film is preferably used from the viewpoint of excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the release film is usually about 5 to 200 μm, preferably about 5 to 100 μm.

  For the release film, if necessary, mold release and antifouling treatment with silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder, etc., coating type, kneading type, vapor deposition An antistatic treatment such as a mold can also be performed. In particular, when the surface of the release film is appropriately subjected to release (release) treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment, the releasability from the pressure-sensitive adhesive layer can be further enhanced.

  When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a release film until practical use. In addition, the said peeling film can be used as a separator of an adhesive optical film as it is, and can simplify in a process surface.

  In the present invention, the above-mentioned pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention) is provided on at least one side of a base material (also referred to as “support” or “support base material”). Thus, a pressure-sensitive adhesive sheet (pressure-sensitive adhesive sheet with a base material; a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer on at least one side of the base material) can be obtained. The pressure-sensitive adhesive layer itself can be used as a substrate-less pressure-sensitive adhesive sheet. Hereinafter, the pressure-sensitive adhesive sheet with the substrate may be referred to as “the pressure-sensitive adhesive sheet of the present invention”.

  The pressure-sensitive adhesive sheet of the present invention (the pressure-sensitive adhesive sheet with the base material) is prepared by, for example, applying the pressure-sensitive adhesive composition of the present invention to the surface on at least one side of the base material and drying it as necessary. It is obtained by forming an adhesive layer on at least one side (direct copying method). Crosslinking is performed by dehydrating in the drying step, heating the pressure-sensitive adhesive sheet after drying, or the like. Moreover, after providing an adhesive layer once on a peeling film, an adhesive sheet can also be obtained by transferring an adhesive layer on a base material (transfer method). Although not particularly limited, the pressure-sensitive adhesive layer is preferably provided by a so-called direct copying method in which the pressure-sensitive adhesive composition is directly applied to the substrate surface.

  As a base material of the pressure-sensitive adhesive sheet of the present invention, a plastic base material (for example, a plastic film or a plastic sheet) is preferable from the viewpoint of obtaining a pressure-sensitive adhesive sheet having high transparency. Although it does not specifically limit as a raw material of a plastic base material, For example, Polyolefin (polyolefin resin), such as a polypropylene and polyethylene, Polyester (polyester resin), such as a polyethylene terephthalate (PET), A polycarbonate, polyamide, a polyimide, an acryl, a polystyrene Transparent resins such as acetate, polyethersulfone, and triacetyl cellulose are used. These resins may be used alone or in combination of two or more. Among the base materials, although not particularly limited, polyester resins and polyolefin resins are preferable, and PET, polypropylene, and polyethylene are preferably used in terms of productivity and moldability. That is, the base material is preferably a polyester film or a polyolefin film, and more preferably a PET film, a polypropylene film or a polyethylene film. Although it does not specifically limit as said polypropylene, The homotype which is a homopolymer, the random type which is an alpha-olefin random copolymer, and the block type which is an alpha-olefin block copolymer are mentioned. Examples of polyethylene include low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (L-LDPE). These may be used singly or in combination of two or more.

  Although the thickness of the said base material is not specifically limited, 10-150 micrometers is preferable, More preferably, it is 30-100 micrometers.

  The surface of the substrate on the side where the pressure-sensitive adhesive layer is provided may be subjected to acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, ultraviolet treatment, etc. for the purpose of improving the adhesion with the pressure-sensitive adhesive layer. It is preferable that an easy adhesion treatment is performed. Moreover, you may provide an intermediate | middle layer between a base material and an adhesive layer. The thickness of the intermediate layer is preferably, for example, 0.05-1 μm, more preferably 0.1-1 μm.

  The pressure-sensitive adhesive sheet of the present invention can be a wound body, and can be wound up in a roll shape with the pressure-sensitive adhesive layer protected by a release film (separator). In addition, the back side of the adhesive sheet (the side opposite to the side where the adhesive layer is provided) is released from silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder, etc. Treatment and / or antifouling treatment may be performed, and a back treatment layer (such as a release treatment layer or an antifouling treatment layer) may be provided. As the pressure-sensitive adhesive sheet of the present invention, the form of pressure-sensitive adhesive layer / base material / back treatment layer is particularly preferable.

  Furthermore, the pressure-sensitive adhesive sheet of the present invention is more preferably subjected to antistatic treatment. As the antistatic treatment, a general antistatic treatment method can be used and is not particularly limited. For example, a method of providing an antistatic layer on the back surface of the substrate (the surface opposite to the adhesive layer). Alternatively, a method of kneading a kneading type antistatic agent into the substrate can be used.

  As a method of providing an antistatic layer, an antistatic agent or an antistatic resin containing an antistatic agent and a resin component, a method of applying a conductive resin composition or a conductive polymer containing a conductive substance and a resin component And a method of depositing or plating a conductive substance.

  Examples of the antistatic agent include cationic antistatic agents having a cationic functional group such as a quaternary ammonium salt and a pyridinium salt (for example, a primary amino group, a secondary amino group, and a tertiary amino group); Anionic antistatic agents with anionic functional groups such as salts, sulfates, phosphonates, phosphates; amphoteric ionic antistatics such as alkylbetaines and their derivatives, imidazolines and their derivatives, alanine and their derivatives Agents; nonionic antistatic agents such as amino alcohol and derivatives thereof, glycerin and derivatives thereof, polyethylene glycol and derivatives thereof; and further, the cationic antistatic agent, anionic antistatic agent, and zwitterionic antistatic agent Obtained by polymerizing or copolymerizing a monomer having an ion conductive group Ion conductive polymer has can be mentioned.

  Specifically, the cationic antistatic agent includes a quaternary ammonium group such as alkyltrimethylammonium salt, acyloylamidopropyltrimethylammonium methosulfate, alkylbenzylmethylammonium salt, acylcholine chloride, and polydimethylaminoethyl methacrylate. Examples thereof include (meth) acrylate copolymers having, styrene copolymers having quaternary ammonium groups such as polyvinylbenzyltrimethylammonium chloride, and diallylamine copolymers having quaternary ammonium groups such as polydiallyldimethylammonium chloride. Examples of the anionic antistatic agent include alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate ester salt, alkyl ethoxy sulfate ester salt, alkyl phosphate ester salt, and sulfonic acid group-containing styrene copolymer. Examples of the zwitterionic antistatic agent include alkyl betaines, alkyl imidazolium betaines, carbobetaine graft copolymers, and the like. Examples of the nonionic antistatic agent include fatty acid alkylolamide, di- (2-hydroxyethyl) alkylamine, polyoxyethylene alkylamine, fatty acid glycerin ester, polyoxyethylene glycol fatty acid ester, sorbitan fatty acid ester, and polyoxysorbitan fatty acid. Examples thereof include esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl ethers, polyethylene glycols, polyoxyethylene diamines, copolymers composed of polyethers, polyesters and polyamides, and methoxypolyethylene glycol (meth) acrylates.

  Examples of the conductive polymer include polyaniline, polypyrrole, and polythiophene.

  Examples of the conductive material include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, iodine. Examples thereof include copper chloride and alloys or mixtures thereof.

  As the resin component, general-purpose resins such as polyester, acrylic, polyvinyl, urethane, melamine, and epoxy are used. When the antistatic agent is a polymer antistatic agent, the antistatic resin may not contain the resin component. In addition, the antistatic resin may contain a methylolated or alkylolized melamine-based, urea-based, glyoxal-based, acrylamide-based compound, epoxy-based compound, or isocyanate-based compound as a crosslinking agent.

  As a forming method by applying the antistatic layer, the antistatic resin, conductive polymer, and conductive resin composition are diluted with a solvent or dispersion medium such as an organic solvent or water, and this coating liquid is used as a base material. The method of apply | coating and drying is mentioned. Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, and isopropanol. These can be used alone or in combination. As the coating method, known coating methods are used, and specific examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, impregnation and curtain coating methods.

  The thickness of the antistatic layer (antistatic resin layer, conductive polymer layer, conductive resin composition layer) formed by the application is preferably 0.001 to 5 μm, more preferably 0.005 to 1 μm. is there.

  Examples of the method for depositing or plating the conductive material include vacuum deposition, sputtering, ion plating, chemical vapor deposition, spray pyrolysis, chemical plating, and electroplating.

  The thickness of the antistatic layer (conductive material layer) formed by vapor deposition or plating is preferably 20 to 10000 mm (0.002 to 1 μm), more preferably 50 to 5000 mm (0.005 to 0.5 μm). is there.

  As the kneading type antistatic agent, the antistatic agent is appropriately used. The blending amount of the kneading-type antistatic agent is preferably 20% by weight or less, more preferably 0.05 to 10% by weight, based on the total weight (100% by weight) of the substrate. The kneading method is not particularly limited as long as the kneading-type antistatic agent is a method that can be uniformly mixed with, for example, a resin used for a plastic substrate. Generally, a heating roll, a Banbury mixer, a pressure kneader is used. And a method using a twin-screw kneader.

[Usage]
The pressure-sensitive adhesive composition of the present invention forms a pressure-sensitive adhesive layer that has excellent antistatic properties, adhesiveness (adhesiveness), removability (light releasability, easy releasability), and appearance characteristics, and can be re-removable. The pressure-sensitive adhesive composition can be used to form a pressure-sensitive adhesive layer used for re-peeling. That is, the adhesive sheet having the adhesive layer is re-peeled [for example, masking tape for building curing, masking tape for automobile coating, masking tape for electronic parts (lead frame, printed circuit board, etc.), masking tape for sandblast, etc. Masking tape, surface protection film for aluminum sash, surface protection film for optical plastic, surface protection film for optical glass, surface protection film for automobile protection, surface protection film for metal plate, back grind tape, Pelicle fixing tape, dicing tape, lead frame fixing tape, cleaning tape, dust removal tape, carrier tape, cover tape, and other semiconductor / electronic component manufacturing process adhesive tape, electronic equipment and electronic component packaging tape In transit Sealing tapes, bundling tapes, preferably used in the label such], and the like.

  The pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) formed from the pressure-sensitive adhesive composition of the present invention does not cause contamination such as whitening contamination on the adherend and is excellent in low contamination when used on an adherend. For this reason, the pressure-sensitive adhesive sheet of the present invention requires polarizing plates, retardation plates, antireflection plates, wavelengths constituting panels of liquid crystal displays, organic electroluminescence (organic EL), field emission displays, etc., which require low contamination. It is preferably used as a surface protection application (a surface protection film for an optical member, etc.) of an optical member (optical plastic, optical glass, optical film, etc.) such as a plate, an optical compensation film, and a brightness enhancement film. However, the application is not limited to this. Surface protection and damage prevention in the manufacture of microfabricated parts such as semiconductors, circuits, various printed boards, various masks, and lead frames, or removal of foreign substances, masking, etc. Can also be used.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following description, “parts” and “%” are based on weight unless otherwise specified.

<Example 1>
(Preparation of acrylic emulsion polymer)
In the container, 90 parts by weight of water and, as shown in Table 1, 92 parts by weight of 2-ethylhexyl acrylate (2EHA), 4 parts by weight of acrylic acid (AA), 4 parts by weight of methyl methacrylate (MMA), reactivity After blending 2 parts by weight of a nonionic anionic emulsifier [Daiichi Kogyo Seiyaku Co., Ltd., trade name “AQUALON HS-1025”], the mixture was stirred and mixed with a homomixer to prepare a monomer emulsion.

  Subsequently, 50 parts by weight of water and 0.07 part by weight of a polymerization initiator (ammonium persulfate) were added to a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, heated to 75 ° C., and then in a nitrogen atmosphere. The monomer emulsion was added over 3 hours with stirring, and emulsion polymerization was further performed at 75 ° C. for 3 hours. Next, this was cooled to 30 ° C. and adjusted to pH 8 by adding ammonia water having a concentration of 10% by weight, and an aqueous dispersion of acrylic emulsion polymer (concentration of acrylic emulsion polymer: 42% by weight) was obtained. Prepared.

(Preparation of water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling)
In the aqueous dispersion of the acrylic emulsion polymer, an epoxy crosslinking agent [Mitsubishi Gas Chemical Co., Ltd., trade name, which is a water-insoluble crosslinking agent, per 100 parts by weight of the acrylic emulsion polymer (solid content) “TETRAD-C”, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, number of functional groups: 4] 1.8 parts by weight, 1-ethyl-3-methylimidazolium bisfluoro 1 part by weight of sulfonylimide [Daiichi Kogyo Seiyaku Co., Ltd., trade name “Elexcel AS-110”, active ingredient 100% by weight], ether group-containing polysiloxane [Shin-Etsu Silicone Co., Ltd., trade name “KF-353” ”, 100% by weight of active ingredient] 0.32 parts by weight, acetylenic diol compound (composition) having an HLB value of 8 [trade name“ Sir Inoru 440 ", the active ingredient 100% by weight] 1 part by weight, using a stirrer, 23 ° C., 2000 rpm, and stirred and mixed at 10-minute stirring at the removable water-dispersible acrylic pressure-sensitive adhesive composition was prepared.

(Formation of adhesive layer, production of adhesive sheet)
Further, the water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling is applied to a corona-treated surface of a PET film (Mitsubishi Resin Co., Ltd., trade name “T100M38”, thickness: 38 μm). Using an applicator, it is applied (coated) so that the thickness after drying is 20 μm, then dried in a hot air circulating oven at 120 ° C. for 2 minutes, and then cured at 50 ° C. for 1 day (aging) Thus, an adhesive sheet was obtained.

<Examples 2-8, Comparative Examples 1-3>
As shown in Table 1, the types and blending amounts of raw material monomers and nonionic surfactants (acetylenic diol compounds) and the like were changed, and the pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1. . In addition, about the additive which is not described in a table | surface, it prepared with the compounding quantity similar to Example 1. FIG.

[Evaluation]
The water-dispersed acrylic pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet obtained in the examples and comparative examples were evaluated by the following measurement method or evaluation method. The evaluation results are shown in Table 2.

<Measurement of average particle diameter of acrylic emulsion polymer>
For the measurement of the average particle size of the emulsion, a LS1332 laser scattering diffraction particle size distribution measuring device manufactured by BECKMANCOULTER was used. The pump speed was 30% and the measurement time was 90 seconds. An emulsion adhesive diluted 10 times was set and measured.

  Since the emulsion particles formed from the acrylic emulsion-based polymer are charged, the ionic liquid is constrained, so that the emulsion particles generally work against the antistatic effect. Therefore, by increasing the average particle size of the emulsion, the antistatic property can be improved, because the total surface area is larger than when the average particle size is small, so that the amount of ionic liquid restrained is large. Since the amount of the ionic liquid is reduced and the ionic liquid is easily bleed out on the surface of the adherend, the antistatic property can be improved.

  In general, since emulsion particles are charged on the particle surface, ionic compounds are liable to be restrained on the surface. As a result, it is presumed that the ionic compound transferred to the adherend is reduced when the pressure-sensitive adhesive is peeled from the adherend, and the antistatic property at the time of peeling is hardly exhibited. Here, when the average particle diameter of the emulsion is increased, the surface area of each particle increases, but the number of particles contained in the same solid content concentration and volume decreases, and the total surface area of the particles decreases. As a result, it is presumed that the ionic compound restrained on the particle surface can be reduced and the antistatic property can be improved. The average particle diameter is preferably 130 to 1000 nm, more preferably 150 to 500 nm, and still more preferably 200 to 450 nm.

[Peeling voltage]
The prepared pressure-sensitive adhesive sheet was cut to a size of 70 mm in width and 120 mm in length, the separator was peeled off, and then the acrylic plate (Mitsubishi Rayon Co., Ltd., acrylite, thickness: 1 mm, width: 70 mm, length, which had been removed in advance) : 100 mm) was bonded to the surface of a polarizing plate (manufactured by Nitto Denko Corporation, trade names “SEG1425DU”, “AGS1”, and “ARC150T” with a hand roller so that one end protruded 20 mm. Next, after being left in an environment of 20 ° C. × 25 ± 2% RH for one day, the sample is set at a predetermined position as shown in FIG. 1. One end protruding 20 mm is placed on an automatic winder. The sample was peeled off at a peeling angle of 150 ° and a peeling speed of 30 m / min, and the potential of the polarizing plate surface generated at this time was fixed at a predetermined position. (KSD-0103, manufactured by Kasuga Denki Co., Ltd.) The distance between the sample and the potential measuring device was 100 mm when measuring the acrylic plate surface, and the measurement was 20 ° C. × 25 ± 2% RH and 23 ° C. × The product names “SEG1425DU”, “AGS1”, and “ARC150T” have the properties of SEG1425DU not treated, AGS1 treated anti-glare, and ARC150T, respectively. Is an anti-reflection treatment.

  The peel voltage (absolute value) of the pressure-sensitive adhesive sheet of the present invention is preferably 1.0 kV or less, more preferably 0.8 kV or less, still more preferably 0.5 kV or less, particularly preferably. Is 0 kV. When the stripping voltage exceeds 1.0 kV, the polarizer arrangement in the polarizing plate is disturbed, and dust is easily adsorbed when the adhesive sheet is stripped, which is not preferable.

[For DU initial peeling force]
The prepared pressure-sensitive adhesive sheet is cut into a size of 25 mm in width and 100 mm in length, the separator is peeled off, and then a polarizing plate (manufactured by Nitto Denko Co., Ltd.) using a bonding machine (manufactured by Tester Sangyo Co., Ltd., a small bonding machine). , SEG1425DU, width: 70 mm, length: 100 mm) was laminated under the conditions of 0.25 MPa and 0.3 m / min to prepare an evaluation sample. After lamination, after leaving for 30 minutes in an environment of 23 ° C. × 50% RH, peeling force (adhesive strength) when peeled at a peeling speed of 0.3 m / min and a peeling angle of 180 ° with a universal tensile tester (N / 25 mm) was measured and was defined as “the initial peel force against DU”. The measurement was performed in an environment of 23 ° C. × 50% RH.

  In addition, as an initial peeling force of the adhesive sheet of this invention, it is preferable that it is 0.1-1.0N / 25mm, More preferably, it is 0.3-0.8N / 25mm. It is preferable to set the peeling force to 1.0 N / 25 mm or less because the adhesive sheet can be easily peeled in the manufacturing process of the polarizing plate and the liquid crystal display device, and productivity and handleability are improved. Moreover, it is preferable by setting it as 0.1 N / 25mm or more because the float and peeling of an adhesive sheet are suppressed at a manufacturing process, and the protective function as an adhesive sheet for surface protection can fully be exhibited.

[Appearance (existence of dents / gels)]
The state of the pressure-sensitive adhesive layer surface of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples was visually observed. The number of defects (dents and gels) within the observation range of 10 cm long × 10 cm wide was measured and evaluated according to the following criteria.
Number of defects: 0 to 100: Good appearance (◯).
The number of defects is 101 or more: the appearance is bad (x).

  In addition, about the mixing | blending content in Table 1, the weight of solid content was shown. The abbreviations used in Table 1 are as follows.

(Monomer component)
2EHA: 2-ethylhexyl acrylate AA: Acrylic acid MMA: Methyl methacrylate

(emulsifier)
HS-1025: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “AQUALON HS-1025” (reactive nonionic anionic emulsifier)

(Crosslinking agent)
T / C: manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name “TETRAD-C” (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, functional group number: 4) (insoluble) Crosslinker)

(Ionic compounds)
AS-110: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “ELEXEL AS-110” (1-ethyl-3-methylimidazolium bisfluorosulfonylimide, active ingredient 100% by weight) (ionic liquid)

(Ether group-containing polysiloxane)
KF-353: Shin-Etsu Silicone Co., Ltd., trade name “KF-353”

(Nonionic surfactant)
Surfynol 420: Product name “Surfinol 420” (HLB value: 4, active ingredient 100 wt%, acetylenic diol compound), manufactured by Air Products
Surfynol 440: Product name “Surfinol 440” (HLB value: 8, active ingredient 100 wt%, acetylenic diol compound) manufactured by Air Products
Surfynol 465: Product name “Surfinol 465” manufactured by Air Products (HLB value: 13, active ingredient 100% by weight, acetylenic diol compound)
Surfynol 485: Product name “Surfinol 485” (HLB value: 17, active ingredient 100% by weight, acetylenic diol compound), manufactured by Air Products
Acetylenol E60: Kawaken Fine Chemicals, trade name “acetylenol E60” (HLB value: 11 to 12, active ingredient 98% by weight or more, acetylene glycol compound)
Acetyleneol E81: manufactured by Kawaken Fine Chemical Co., Ltd., trade name “acetylene E81” (HLB value: 12.2, active ingredient 98% by weight or more, acetylene glycol compound)
Acetylenol E100: manufactured by Kawaken Fine Chemical Co., Ltd., trade name “acetylenol E100” (HLB value: 13 to 14, active ingredient 98% by weight or more, acetylene glycol compound)

  From the evaluation results of Table 2 above, it was confirmed that an adhesive layer (adhesive sheet) excellent in antistatic properties, removability and appearance characteristics was obtained in all Examples.

  On the other hand, from the evaluation results in Table 2 above, in Comparative Example 1, since a nonionic surfactant having a specific HLB value was not used, the antistatic property and appearance characteristics were inferior. In Comparative Examples 2 and 3, Although an acetylenic diol compound, which is a nonionic surfactant having a specific HLB value, was blended, a nonionic surfactant having a specific HLB value was not used, resulting in poor antistatic properties. In particular, the non-polar surfactant having a specific HLB value was not used as the reason why the peeling voltage on the surface of the ARC150T having a low polarity was inferior to that of the examples. ) Is difficult to transcribe.

1 Potential measuring device 2 Adhesive sheet 3 Polarizing plate 4 Acrylic plate 5 Sample fixing base

Claims (4)

(Meth) acrylic acid alkyl ester 70 to 99.5% by weight and carboxyl group-containing unsaturated monomer 0.5 to 10% by weight as monomer components acrylic emulsion polymer, crosslinking agent, ionic compound And containing a nonionic surfactant having an HLB value of 6 or more,
The ionic compound contains at least one of an anion containing a fluorine atom, an anion containing a nitrogen atom, and an anion having a sulfonyl group, and a water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling. (Meth) acrylic acid alkyl ester 70 to 99.5% by weight and carboxyl group-containing unsaturated monomer 0.5 to 10% by weight as monomer components acrylic emulsion polymer, crosslinking agent, ionic compound And containing a nonionic surfactant having an HLB value of 6 or more,
The ionic compound is an ionic liquid;
The ionic liquid contains at least one cation selected from the group consisting of cations represented by the following formulas (A) to (E), and is a water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling.

[R _a in Formula (A) represents a hydrocarbon group having 4 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, and R _b and R _c May be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. However, when the nitrogen atom contains a double bond, there is no R _c . ]
[R _d in Formula (B) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, and R _e , R _f And R _g may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. ]
[R _h in Formula (C) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a heteroatom, R _i , R _j , And R _k may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. ]
[Z in Formula (D) represents a nitrogen, sulfur, or phosphorus atom, and R ₁ , R _m , R _n , and R _o are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms. In addition, a functional group in which a part of the hydrocarbon group is substituted with a hetero atom may be used. However, when Z is a sulfur atom, there is no _Ro . ]
[R _P in the formula (E) represents a hydrocarbon group having 1 to 18 carbon atoms, a part of the hydrocarbon group may be substituted by a functional group with a heteroatom. ]   The water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling according to claim 1 or 2, wherein the nonionic surfactant contains an acetylene structure. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling according to claim 1 on at least one side of a substrate.