JP6238608B2 - Re-peeling water-dispersed acrylic pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet and optical member - Google Patents

Description

  The present invention relates to a water-dispersed acrylic pressure-sensitive adhesive composition capable of forming a re-peelable pressure-sensitive adhesive layer. Moreover, it is related with the adhesive sheet which has an adhesive layer formed from this adhesive composition, and the optical member with which this adhesive sheet was stuck.

  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. As these surface protective films, a releasable pressure-sensitive adhesive sheet in which a removable pressure-sensitive adhesive layer is provided on the surface of a plastic film substrate is used (see Patent Documents 1 and 2).

JP 2008-69261 A JP-A-11-116927

  Such a surface protective film has a better pick-up property (for an optical member having a surface protective film affixed to the surface than an optical member) for an optical member having a highly polar surface (for example, a polarizing plate having a highly polar surface). It exhibited a property indicating the ease of taking off when the protective film was peeled off. However, there are cases where good pickup properties cannot be exhibited for an optical member having a low polarity surface (for example, a polarizing plate having a low polarity surface).

  For this reason, in addition to the adherend having a high polarity on the application surface, an adhesive sheet capable of exhibiting good pick-up properties even on an adherend having a low polarity application surface, and an adhesive layer possessed by the adhesive sheet are formed. There is a need for a pressure-sensitive adhesive composition.

  In addition, when the surface protective film is attached to an optical member, the optical member attached with the surface protective film has an unnecessary curl or unintentional curl (curling is a phenomenon in which the curl is warped. There has been a strong demand not to cause a phenomenon in which the entire surface is warped, a phenomenon in which a flat plate is generally warped, or the like. Optical members that tend to cause curling are increasingly used, and the occurrence of unnecessary or unintended curling causes defects in the process of manufacturing a product using the optical member (for example, a liquid crystal panel). It is a cause.

  Therefore, a pressure-sensitive adhesive sheet capable of adjusting the occurrence of unnecessary or unintended curling on an adherend (for example, an optical member) to which a pressure-sensitive adhesive sheet is attached, and a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet Is required.

  However, the pick-up property and the curl adjustment are in a trade-off relationship, and the present situation is that no one satisfying both characteristics has been obtained.

Accordingly, an object of the present invention is to provide a water-removable acrylic adhesive for re-peeling that can form a pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet that can exhibit good pick-up properties regardless of the polarity of the sticking surface, and can also exhibit good curl adjustability. It is to provide an agent composition.
Another object of the present invention is to provide a pressure-sensitive adhesive sheet that can exhibit good pick-up properties regardless of the polarity of the sticking surface and can exhibit good curl adjustment properties, and an optical member on which the pressure-sensitive adhesive sheet is stuck. Is to provide.

  Therefore, as a result of intensive studies by the present inventors in order to solve the above-mentioned problems, the water-dispersed acrylic pressure-sensitive adhesive composition, an acrylic emulsion polymer having a specific raw material monomer as a constituent monomer component, a water-insoluble When the composition contains a crosslinking agent, an ether group-containing polysiloxane, and an acetylenic diol compound, and the relationship between the content of the water-insoluble crosslinking agent and the content of the ether group-containing polysiloxane is a specific relationship, It was found that even if the surface is low polarity or the sticking surface is high polarity, it is possible to form a pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet that can exhibit good pick-up properties and good curl adjustability. Completed the invention.

That is, the present invention contains an acrylic emulsion polymer, a water-insoluble crosslinking agent, an acetylenic diol compound and an ether group-containing polysiloxane,
The acrylic emulsion-based polymer is composed of (meth) acrylic acid alkyl ester and carboxyl group-containing unsaturated monomer as essential raw material monomers, and the content of the (meth) acrylic acid alkyl ester is based on the total amount of raw material monomers. 70 to 99.5% by weight, and the content of the carboxyl group-containing unsaturated monomer is 0.5 to 10.0% by weight with respect to the total amount of raw material monomers,
The content of the water-insoluble crosslinking agent is X parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer, and the content of the ether group-containing polysiloxane is Y with respect to 100 parts by weight of the acrylic emulsion polymer. A water-dispersed acrylic pressure-sensitive adhesive composition for re-peeling, characterized in that it is part by weight and the value (A) obtained by the following formula (1) is 3 or more.
Value (A) = X + (Y × 3) (1)

  The acrylic emulsion polymer is preferably a polymer polymerized using a reactive emulsifier having a radical polymerizable functional group in the molecule.

  The content of the water-insoluble crosslinking agent is preferably 2.15 to 3.0 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer.

  The content of the ether group-containing polysiloxane is preferably 0.16 to 0.50 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer.

  Furthermore, this invention provides the adhesive sheet characterized by having the adhesive layer formed from the said water-dispersible acrylic adhesive composition for re-peeling.

  Furthermore, this invention provides the optical member characterized by the above-mentioned adhesive sheet being affixed.

According to the water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling of the present invention, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet can exhibit good pick-up properties regardless of the polarity of the application surface, and can exhibit good curl adjustability. Can be formed.
In addition, since the pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer formed from the above-described re-peeling water-dispersed acrylic pressure-sensitive adhesive composition, it can exhibit good pick-up properties regardless of the polarity of the application surface, and is good The curl can be adjusted.

[Re-peeling water-dispersed acrylic pressure-sensitive adhesive composition]
The water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling of the present invention contains at least an acrylic emulsion polymer, a water-insoluble crosslinking agent, an acetylenic diol compound, and an ether group-containing polysiloxane. In the present specification, the water-dispersed acrylic pressure-sensitive adhesive composition for re-peeling of the present invention may be simply referred to as “the acrylic pressure-sensitive adhesive composition of the present invention”.

  The acrylic pressure-sensitive adhesive composition of the present invention is a “water-dispersed” pressure-sensitive adhesive composition. The “water dispersion type” means that it can be dispersed in an aqueous medium. That is, the acrylic pressure-sensitive adhesive composition of the present invention is a pressure-sensitive 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 acrylic pressure-sensitive adhesive composition of the present invention may be a dispersion using the above aqueous medium.

  The acrylic pressure-sensitive adhesive composition of the present invention is a composition that forms a pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention has removability, and when it is peeled off after being attached to an adherend, the pressure-sensitive adhesive sheet or the adherend is destroyed. Without being generated, the pressure-sensitive adhesive can be peeled off without leaving it on the adherend surface. In the present specification, “adhesive tape or sheet (pressure-sensitive adhesive tape or sheet)” is simply referred to as “adhesive tape (pressure-sensitive adhesive tape)” or “adhesive sheet (pressure-sensitive adhesive sheet)”. There is a case.

(Acrylic emulsion polymer)
The acrylic pressure-sensitive adhesive composition of the present invention contains at least an acrylic emulsion polymer. The said acrylic emulsion type polymer can be used individually or in combination of 2 or more types. In the present specification, “(meth) acryl” means “acryl and / or methacryl”.

  The content of the acrylic emulsion polymer in the acrylic pressure-sensitive adhesive composition of the present invention is not particularly limited, but the total solid content of the acrylic pressure-sensitive adhesive composition of the present invention (total weight of solid content, 100% by weight). On the other hand, it is preferably 80% by weight or more, more preferably 85% by weight or more.

  The acrylic emulsion polymer is a polymer formed using (meth) acrylic acid alkyl ester and a carboxyl group-containing unsaturated monomer as essential raw material monomers. In other words, the acrylic emulsion polymer contains at least a (meth) acrylic acid alkyl ester and a carboxyl group-containing unsaturated monomer as the constituent monomer components.

  In the acrylic emulsion polymer, the content of the (meth) acrylic acid alkyl ester is 70 to 99.5% by weight based on the total amount of the raw material monomers, and the content of the carboxyl group-containing unsaturated monomer. Is 0.5 to 10.0% by weight based on the total amount of raw material monomers. In other words, in the acrylic emulsion polymer, the content of the (meth) acrylic acid alkyl ester is 70 to 99.99 with respect to the total amount of monomer components (100% by weight) constituting the acrylic emulsion polymer. 5% by weight, and the content of the carboxyl group-containing unsaturated monomer is 0.5 to 10.0% with respect to the total amount of monomer components (total weight, 100% by weight) constituting the acrylic emulsion polymer. %.

  The (meth) acrylic acid alkyl ester is a main monomer component constituting an acrylic emulsion polymer, and mainly plays a role of developing basic characteristics as a pressure-sensitive adhesive (or pressure-sensitive adhesive layer) such as adhesiveness and peelability. Bear. Among them, alkyl acrylate ester tends to give flexibility to the acrylic emulsion polymer used as the base polymer, and to exert the effect of exhibiting adhesiveness and adhesiveness in the pressure-sensitive adhesive layer. There exists a tendency which gives hardness to the acrylic emulsion-type polymer used as this, and exhibits the effect of adjusting the removability of an adhesive layer.

  Although it does not specifically limit as said (meth) acrylic-acid alkylester, The (meth) acrylic-acid alkylester which has a C1-C20 linear, branched or cyclic alkyl group is mentioned preferably. In addition, the said (meth) acrylic-acid alkylester can be used individually or in combination of 2 or more types.

  Especially, as said (meth) acrylic-acid alkylester, the acrylic acid alkylester which has a C1-C16 linear or branched alkyl group is mentioned preferably. In the acrylic acid alkyl ester, the upper limit of the carbon number of the alkyl group is more preferably 12 or less, and still more preferably 10 or less. On the other hand, the lower limit of the carbon number of the alkyl group is more preferably 2 or more, and further preferably 4 or more.

  Examples of the alkyl acrylate ester having a linear or branched alkyl group include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, 1-methylethyl acrylate, n-butyl acrylate, and isobutyl acrylate. S-butyl acrylate, pentyl acrylate, isoamyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, isononyl acrylate, decyl acrylate, acrylic Examples include acid undecyl, dodecyl acrylate, tridecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, and the like. Of these, 2-ethylhexyl acrylate and n-butyl acrylate are preferable. The acrylic acid alkyl ester having a linear or branched alkyl group can be used alone or in combination of two or more.

  Furthermore, as said (meth) acrylic-acid alkylester, the methacrylic acid alkylester which has a C1-C16 alkyl group is mentioned preferably. In the methacrylic acid alkyl ester, the upper limit of the carbon number of the alkyl group is more preferably 12 or less, and further preferably 10 or less.

  Examples of the alkyl methacrylate include, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, 1-methylethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, and t-butyl methacrylate. , Pentyl methacrylate, isoamyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate Methacrylic acid alkyl ester having a linear or branched alkyl group such as tridecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, etc. It is below. Furthermore, alicyclic methacrylic acid alkyl esters such as cyclohexyl methacrylate, bornyl methacrylate, and isobornyl methacrylate are exemplified. Of these, methyl methacrylate, ethyl methacrylate, and butyl methacrylate are preferable. In addition, the said methacrylic acid alkylester can be used individually or in combination of 2 or more types.

The above-mentioned acrylic emulsion polymer has good adhesion to an adherend (particularly uneven surface) by reducing the repelling of the water-insoluble crosslinking agent in the pressure-sensitive adhesive layer formed by the acrylic pressure-sensitive adhesive composition of the present invention. from the point of obtaining the adhesion and followability) for, as a (meth) acrylic acid alkyl ester as a raw material monomer preferably contains an alkyl acrylate and methacrylic San'a Ruki glycol ester. In particular, the raw material monomer preferably contains an acrylic acid alkyl ester having a linear or branched alkyl group and a methacrylic acid alkyl ester having a linear or branched alkyl group, and acrylic acid 2 A group consisting of an alkyl acrylate ester having at least one linear or branched alkyl group selected from the group consisting of ethylhexyl and n-butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate It is more preferable to include at least one alkyl methacrylate having at least one linear or branched alkyl group.

When used acrylic acid alkyl ester and a methacrylic San'a Ruki glycol ester as raw material monomers for the acrylic emulsion polymer, the ratio (by weight) is not particularly limited, (acrylic acid alkyl ester) / (methacrylic San'a in Ruki glycol ester), preferably 99 / 1-70 / 30, more preferably 99 / 1-80 / 20.

  Content of the said (meth) acrylic-acid alkylester is 70-99.5 weight% with respect to the total amount (total amount) (total raw material monomer) (100 weight%) of the raw material monomer which comprises an acrylic emulsion type polymer. . The upper limit of the content of the (meth) acrylic acid alkyl ester is more preferably 99% by weight or less, and still more preferably 98% by weight or less. The lower limit is more preferably 80% by weight or more, and still more preferably 85% by weight or more. When the content is less than 70% by weight, the adhesiveness and removability of the pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition may be lowered. On the other hand, when the content exceeds 99.5% by weight, the content of the carboxyl group-containing unsaturated monomer is lowered, and thus the anchoring property and low contamination of the pressure-sensitive adhesive layer formed by the acrylic pressure-sensitive adhesive composition are reduced. Properties and emulsion stability may be reduced.

  The acrylic emulsion polymer contains a carboxyl group-containing unsaturated monomer as a raw material monomer together with the (meth) acrylic acid alkyl ester. The said carboxyl group-containing unsaturated monomer forms the protective layer on the emulsion particle surface which consists of an acryl emulsion type polymer, and can exhibit the function which prevents the shear destruction of particle | grains. This 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. Further, by combining one or more polyfunctional compounds (for example, polyfunctional epoxy compounds) that react with a carboxyl group, it can also act as a crosslinking point in the pressure-sensitive adhesive layer forming stage by water removal. Furthermore, adhesion (throwing property) can also be improved through a polyfunctional compound.

  Examples of the carboxyl group-containing unsaturated monomer 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. In addition, the said carboxyl group-containing unsaturated monomer can be used individually or in combination of 2 or more types.

Content of the said carboxyl group-containing unsaturated monomer is 0.5-10.0 weight% with respect to the whole quantity (total raw material monomer) (100 weight%) of the raw material monomer which comprises the said acrylic emulsion type polymer. is there.
The upper limit of the content of the carboxyl group-containing unsaturated monomer is preferably 5.0% by weight or less, and more preferably 4.0% by weight or less. Moreover, the lower limit is preferably 1.0% by weight or more, and more preferably 2.0% by weight or more. 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 a case. Furthermore, after forming the adhesive layer from the adhesive composition, the interaction with the functional group on the surface of the adherend increases, the adhesive force increases over time, the peeling becomes difficult, and the pick-up property decreases. There is. On the other hand, if the content is less than 0.5% by weight, the mechanical stability of the emulsion particles may be lowered. In addition, the adhesion (throwing property) may be reduced, which may cause adhesive residue.

  For the purpose of imparting a specific function as a constituent monomer component (raw material monomer), the acrylic emulsion-based polymer, together with the (meth) acrylic acid alkyl ester and the carboxyl group-containing unsaturated monomer, “other monomers” "(Other monomer components other than the (meth) acrylic acid alkyl ester and the carboxyl group-containing unsaturated monomer) may be included. In addition, the said other monomer can be used individually or in combination of 2 or more types.

For example, for the purpose of improving the cohesive force, the acrylic emulsion-based polymer may contain amide group-containing monomers such as (meth) acrylamide, N, N-diethyl (meth) acrylamide, and N-isopropyl (meth) acrylamide as raw material monomers. At least one other monomer selected from the group consisting of amino group-containing monomers such as N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate is used as the acrylic emulsion polymer. May be contained in an amount of 0.1 to 15% by weight based on the total amount of raw material monomers (total raw material monomer) (100% by weight).
The acrylic emulsion polymer is used as a raw material monomer for the purpose of adjusting the refractive index, reworkability, and the like, and (meth) acrylic acid aryl esters such as phenyl (meth) acrylate; vinyl such as vinyl acetate and vinyl propionate. Esters; at least one other monomer selected from the group consisting of styrene monomers such as styrene, with respect to the total amount of raw material monomers (total raw material monomers) (100% by weight) constituting the acrylic emulsion polymer , 15% by weight or less may be contained.
Furthermore, the above-mentioned acrylic emulsion-based polymer is used as a raw material monomer for the purpose of cross-linking emulsion particles and improving cohesion, and epoxy group-containing monomers such as glycidyl (meth) acrylate and allyl glycidyl ether, and trimethylolpropane tri (meth) acrylate. And containing at least one polyfunctional monomer selected from the group consisting of divinylbenzene in an amount of less than 5% by weight based on the total amount of raw material monomers (total raw material monomer) (100% by weight) constituting the acrylic emulsion polymer. You may do it.
Furthermore, the acrylic emulsion-based polymer forms hydrazide crosslinking by using a hydrazide-based crosslinking agent in combination, and as a raw material monomer, particularly diacetone acrylamide (DAAM), allyl acetoacetate, The keto group-containing unsaturated monomer such as 2- (acetoacetoxy) ethyl (meth) acrylate is based on the total amount of raw material monomers constituting the acrylic emulsion polymer (total raw material monomer) (100% by weight). You may contain less than 10 weight% (preferably 0.5-5 weight%).

  In addition, the above-mentioned other monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxy Octyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2- Examples include hydroxyl group-containing unsaturated monomers such as hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. In addition, the said hydroxyl group containing unsaturated monomer is used individually or in combination of 2 or more types.

  The content of the hydroxyl group-containing unsaturated monomer is preferably smaller from the viewpoint of further reducing whitening contamination. Specifically, the content of the hydroxyl group-containing unsaturated monomer is less than 1% by weight with respect to the total amount of raw material monomers (total raw material monomer) (100% by weight) constituting the acrylic emulsion polymer. Is preferable, more preferably less than 0.1% by weight, still more preferably substantially free (for example, less than 0.05% by weight). However, when the purpose is to introduce a crosslinking point such as crosslinking of a hydroxyl group and an isocyanate group or crosslinking of a metal bridge, it may be 0.01 to 10% by weight.

  In particular, the above-mentioned acrylic emulsion-based polymer, from the point of improving the appearance of the pressure-sensitive adhesive sheet obtained from the acrylic pressure-sensitive adhesive composition of the present invention and the pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention, As the constituent monomer component (raw material monomer), it is preferable to contain at least one monomer selected from the group consisting of methyl methacrylate, isobornyl acrylate, N, N-diethylacrylamide and vinyl acetate, and particularly methyl methacrylate. It is preferable to contain. From the group consisting of the above monomers (methyl methacrylate, isobornyl acrylate, N, N-diethylacrylamide and vinyl acetate) in the total amount of raw material monomers (total raw material monomers) (100% by weight) constituting the acrylic emulsion polymer. The content of the selected monomer) is preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, and still more preferably 2 to 5% by weight. When the content is less than 0.5% by weight, the effect of improving the appearance may not be obtained, and when the content exceeds 15% by weight, a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition is formed. , It may cause a decrease in adhesion. In the case where 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 , Methyl methacrylate, isobornyl acrylate, N, N-diethylacrylamide and vinyl acetate may be contained in a total amount (total content) within the above range.

  The acrylic emulsion polymer is obtained by polymerizing the raw material monomers. Specifically, the acrylic emulsion polymer is preferably obtained by polymerizing a mixture (monomer mixture) containing at least the raw material monomer. The polymerization method is not particularly limited, but emulsion polymerization is preferred. For example, the acrylic emulsion polymer is preferably obtained by emulsion polymerization of a mixture containing the raw material monomer and an emulsifier (surfactant). The said mixture may contain the polymerization initiator as needed, and the chain transfer agent may be contained from the point which adjusts the molecular weight of the said acrylic emulsion type polymer.

  Although the said emulsifier is not specifically limited, A reactive emulsifier (reactive surfactant) is preferable from the point which reduces the contamination derived from an emulsifier. The reactive emulsifier refers to an emulsifier having reactivity and reacting with a raw material monomer to be taken into a polymer (in the polymer). In addition, the said emulsifier can be used individually or in combination of 2 or more types.

  Although it does not specifically limit as said reactive emulsifier, The reactive emulsifier which has a radically polymerizable functional group in a molecule | numerator is preferable. That is, the acrylic emulsion polymer is preferably a polymer polymerized using a reactive emulsifier having a radical polymerizable functional group in the molecule. In the present specification, the “reactive emulsifier having a radical polymerizable functional group in the molecule” may be simply referred to as “reactive emulsifier”.

  Examples of the radical polymerizable functional group in the reactive emulsifier having a radical polymerizable functional group in the molecule include, for example, vinyl group, propenyl group, isopropenyl group, vinyl ether group (vinyloxy group), allyl ether group (allyloxy group). Etc.

  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 a propenyl group or an allyl ether group is introduced into an anionic emulsifier having a hydrophilic hydrophilic group) (or corresponding to the form) Can be mentioned. In the present specification, a reactive emulsifier having a form in which a radically polymerizable functional group is introduced into an anionic emulsifier may be referred to as an “anionic reactive emulsifier”, and the nonionic anionic emulsifier may be radically polymerizable. A reactive emulsifier having a form into which a functional group has been introduced may be referred to as a “nonionic anionic reactive emulsifier”.

  In particular, the reactive emulsifier is preferably an anionic reactive emulsifier, more preferably a nonionic anionic reactive emulsifier, from the viewpoint that the low contamination property can be improved.

  The anionic reactive emulsifier (particularly nonionic anionic reactive emulsifier) is crosslinked by its catalytic action when the water-insoluble crosslinking agent described later is a polyfunctional epoxy crosslinking agent having an epoxy group. The reactivity of the agent can be improved. In the case where the anionic reactive emulsifier is not used, in the pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition, the aging does not complete the crosslinking reaction, and there may be a problem that the adhesive force changes with time. is there. Furthermore, there may be a problem that the adhesive force with the adherend increases with time due to unreacted carboxyl groups. Further, since the anionic reactive emulsifier is incorporated in the polymer, it is generally used as a catalyst for an epoxy crosslinking agent, such as a quaternary ammonium compound (for example, see JP-A-2007-31585). In addition, since it does not precipitate on the surface of the adherend, it cannot cause whitening contamination, which is preferable.

  As such reactive emulsifiers, trade names “Adekalia Soap SE-10N”, “Adekalia Soap SE-20N”, “Adekalia Soap SR-10”, “Adekalia Soap SR-20” (manufactured by ADEKA Corporation), Commercially available products such as “AQUALON HS-05”, “AQUALON HS-10”, “AQUALON HS-1025” (Daiichi Kogyo Seiyaku Co., Ltd.), and “Latemul PD-104” (manufactured by Kao Corporation) are used. It is also possible.

  When obtaining the acrylic emulsion polymer, the amount of the emulsifier blended (used) in the mixture containing the raw material monomer is not particularly limited, but the total amount of raw material monomer constituting the acrylic emulsion polymer ( 0.1 to 10 parts by weight is preferable with respect to 100 parts by weight of all raw material monomers). For example, when the emulsifier is the reactive emulsifier, the blending amount (usage amount) is 0.1 with respect to 100 parts by weight of the total amount of raw material monomers (total raw material monomers) constituting the acrylic emulsion polymer. Is preferably 10 to 10 parts by weight, more preferably 0.5 to 6 parts by weight, and still more preferably 1.0 to 4.5 parts by weight. If the amount is too small, stable emulsification may not be maintained. Moreover, when there are too many said compounding quantities, the cohesive force of the adhesive (adhesive layer) formed with the acrylic adhesive composition will fall, the amount of contamination to a to-be-adhered body will increase, or the contamination by an emulsifier will be carried out. May happen.

  As described above, a polymerization initiator may be included in the mixture containing the raw material monomers for obtaining the acrylic emulsion polymer, if necessary. The polymerization initiator 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′-azobis (N, N′-dimethyleneisobutyl) Azo polymerization initiators such as amidine); persulfates such as potassium persulfate and ammonium persulfate; peroxide polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide and hydrogen peroxide; Examples include redox initiators in combination with a reducing agent. Examples of the redox initiator include a combination of peroxide and ascorbic acid (a combination of hydrogen peroxide and ascorbic acid), a combination of peroxide and iron (II) salt (hydrogen peroxide). And a combination of iron (II) salt and the like, and a redox polymerization initiator by a combination of persulfate and sodium bisulfite. In addition, the said polymerization initiator can be used individually or in combination of 2 or more types.

  The amount of the polymerization initiator blended (used) in the mixture containing the raw material monomer when obtaining the acrylic emulsion polymer is not particularly limited, but the raw material monomer constituting the acrylic emulsion polymer 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).

  As described above, a chain transfer agent may be contained in the mixture containing the raw material monomer for obtaining the acrylic emulsion polymer from the viewpoint of adjusting the molecular weight of the acrylic emulsion polymer. The chain transfer agent is not particularly limited, and examples thereof include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimethylcapto-1-propanol. Is mentioned. In addition, the said chain transfer agent can be used individually or in combination of 2 or more types.

  When the acrylic emulsion polymer is obtained, the amount of the chain transfer agent blended (used) in the mixture containing the raw material monomer is not particularly limited, but the raw material monomer constituting the acrylic emulsion polymer. 0.001 to 0.5 parts by weight is preferable with respect to 100 parts by weight of the total amount (total raw material monomers).

  The emulsion polymerization for obtaining the acrylic emulsion polymer may be any method such as general batch polymerization, continuous dropping polymerization, and divided dropping polymerization, and the method is not particularly limited. From the viewpoint of reducing contamination, it is desirable to perform polymerization at the same time and at a low temperature (for example, 55 ° C. or less, preferably 30 ° C. or less). When polymerization is performed under such conditions, it is presumed that contamination is reduced because high molecular weight products are easily obtained and low molecular weight products are reduced.

  The solvent-insoluble content of the acrylic emulsion polymer (ratio of solvent-insoluble component, sometimes referred to as “gel fraction”) is not particularly limited, but is preferably 70% (% by weight) or more, more preferably 75% by weight. % Or more, more preferably 80% by weight or more. When the solvent-insoluble content is less than 70% by weight, the acrylic emulsion polymer (A) contains a large amount of low molecular weight substances, so that the low molecular weight component in the pressure-sensitive adhesive layer cannot be sufficiently reduced only by the effect of crosslinking. Therefore, adherend contamination derived from low molecular weight components or the like may occur or the adhesive strength may become 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%.

The solvent-insoluble content of the acrylic emulsion polymer is a value calculated by the following “method for measuring solvent-insoluble content”.
(Measurement method of solvent insoluble matter)
Acrylic emulsion polymer: About 0.1 g was sampled, 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 bound with a string. The weight at the time 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 bound with a kite string (referred to as “sample”) is placed in a 50 ml container filled with ethyl acetate and left at 23 ° C. for 7 days. To do. 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 bag, and c is the weight before immersion.)

(Water-insoluble crosslinking agent)
The acrylic pressure-sensitive adhesive composition of the present invention contains at least a water-insoluble crosslinking agent. The water-insoluble crosslinking agent is a water-insoluble compound having two or more functional groups capable of reacting with a carboxyl group in a molecule (in one molecule). In addition, the said water-insoluble crosslinking agent can be used individually or in combination of 2 or more types.

Since the acrylic pressure-sensitive adhesive composition of the present invention contains a water-insoluble crosslinking agent, the crosslinking density of the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition can be increased, and the pressure-sensitive adhesive layer and the adherend are adhered to each other. The force can be prevented from increasing over time. In addition, since the acrylic emulsion polymer as the base polymer is constrained in the pressure-sensitive adhesive layer, the functional groups (particularly carboxyl groups) in the pressure-sensitive adhesive layer segregate on the adherend surface, and the pressure-sensitive adhesive layer and the adherend Can be prevented from increasing over time. Thus, the acrylic pressure-sensitive adhesive composition of the present invention can prevent the adhesive force between the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and the adherend from increasing with time, and thus the pressure-sensitive adhesive composition Good pick-up property can be obtained in the pressure-sensitive adhesive layer formed of a product. Furthermore, the crosslink density of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition can be increased, and the rigidity of the pressure-sensitive adhesive layer can be increased, so that good curl adjustability can be obtained.
In addition, since the acrylic pressure-sensitive adhesive composition of the present invention contains the water-insoluble crosslinking agent, it is possible to prevent the wetting and spreading of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition.

  The number of functional groups capable of reacting with a carboxyl group in the water-insoluble crosslinking agent is not particularly limited as long as it is 2 or more, preferably 2 to 6, more preferably 2 to 5, More preferably, it is 3-5. In addition, when there are too many functional groups which can react with the said carboxyl group, a gelled material may arise and it is unpreferable.

  Although it does not specifically limit as a functional group which can react with the carboxyl group in the said water-insoluble crosslinking agent, For example, an epoxy group, an isocyanate group, a carbodiimide group etc. are mentioned. Among them, the reactivity is high, the unreacted product in the cross-linking reaction hardly remains, and it is advantageous for low contamination, and the adhesive force with the adherend increases with time due to the unreacted carboxyl group in the adhesive layer. From the viewpoint of preventing and obtaining good pickup properties, an epoxy group is preferred, and a glycidylamino group is more preferred. That is, the water-insoluble crosslinking agent is preferably an epoxy-based crosslinking agent having an epoxy group as a functional group capable of reacting with a carboxyl group, and more preferably a crosslinking having a glycidylamino group as a functional group capable of reacting with a carboxyl group. Agent (glycidylamino-based crosslinking agent). When the water-insoluble crosslinking agent is an epoxy crosslinking agent (especially glycidylamino crosslinking agent), the number of epoxy groups (especially glycidylamino group) in one molecule is 2 or more, preferably 2 It is -6, More preferably, it is 2-5, More preferably, it is 3-5.

  The water-insoluble crosslinking agent 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 The amount is not more than parts by weight, more preferably not more than 2 parts by weight. 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 crosslinking only with a water-soluble crosslinking agent, in a high-humidity environment, the remaining crosslinking agent dissolves in moisture 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 adhesive force from increasing with time. Furthermore, since the water-insoluble crosslinking agent has a high crosslinking reaction reactivity, the crosslinking reaction proceeds promptly by aging, and the adhesive force with the adherend increases with time due to unreacted carboxyl groups in the adhesive layer. Can be prevented. If the adhesive force of the pressure-sensitive adhesive layer can be prevented from increasing over time, good pickup properties can be easily obtained.

In addition, the solubility with respect to water of said crosslinking agent can be measured as follows, for example.
(Measurement method of water solubility)
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, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (for example, trade name “TETRAD-C” manufactured by Mitsubishi Gas Chemical Co., Ltd.) [ 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-X” manufactured by Mitsubishi Gas Chemical Co., Ltd.) Glycidylamino-based crosslinking agent such as [solubility of 2 parts by weight or less with respect to 100 parts by weight of water at 25 ° C.]; Tris (2,3-epoxypropyl) isocyclicate (for example, trade name “TEPIC-G” manufactured by Nissan Chemical Industries, Ltd.) ) [Solubility of 2 parts by weight or less with respect to 100 parts by weight of water at 25 ° C.].

  When the water-insoluble crosslinking agent is blended when the acrylic pressure-sensitive adhesive composition of the present invention is prepared, the water-insoluble crosslinking agent may be added (blended) as a liquid water-insoluble crosslinking agent as it is. Alternatively, it may be added after being dissolved and / or diluted with an organic solvent (however, the amount of the organic solvent used is preferably as small as possible). The method of emulsifying and adding a water-insoluble cross-linking agent with an emulsifier is not preferable because the emulsifier bleeds and easily causes contamination (particularly whitening contamination).

The acrylic pressure-sensitive adhesive composition of the present invention contains at least an acrylic emulsion-based polymer, a water-insoluble crosslinking agent, an acetylenic diol compound, and an ether group-containing polysiloxane, but in the acrylic pressure-sensitive adhesive composition of the present invention. The content of the water-insoluble cross-linking agent is such that the content of the water-insoluble cross-linking agent is X parts by weight with respect to 100 parts by weight of the kryl emulsion polymer, and the content of the ether group-containing polysiloxane is an acrylic emulsion. When it is set to Y parts by weight with respect to 100 parts by weight of the polymer, it is an amount such that the value (A) obtained by the following formula (1) is 3 or more.
Value (A) = X + (Y × 3) (1)
When the content of the water-insoluble crosslinking agent in the acrylic pressure-sensitive adhesive composition of the present invention is an amount such that the value (A) obtained by the formula (1) is less than 3, it is in a trade-off relationship. This is because it is impossible to obtain both characteristics of a certain pickup property and curl adjustment at the same time.

Specifically, the content of the water-insoluble crosslinking agent is preferably 0.8 to 5.0 parts by weight, more preferably 1.5 parts with respect to 100 parts by weight of the acrylic emulsion polymer. It is -4.0 weight part, More preferably, it is 2.15-3.0 weight part. When the content of the water-insoluble crosslinking agent is 0.8 parts by weight or more, it is possible to prevent the adhesive force between the adhesive layer formed from the adhesive composition and the adherend from increasing with time. In the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, good pick-up properties are easily obtained, which is preferable. Moreover, the crosslinking density of the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition can be increased, the rigidity of the pressure-sensitive adhesive layer can be increased, and good curl adjustability can be easily obtained, which is preferable. Further, when the content of the water-insoluble crosslinking agent is 5.0 parts by weight or less, in the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition , the water-insoluble crosslinking agent remains without being crosslinked and contaminated. This is preferable because it can effectively prevent the cause.

(Acetylene diol compounds)
The acrylic pressure-sensitive adhesive composition of the present invention contains at least an acetylenic diol compound. Since the acrylic pressure-sensitive adhesive composition of the present invention contains an acetylene diol compound, it is possible to suppress the occurrence of poor appearance due to a dent defect derived from the water-insoluble crosslinking agent in the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition. This is presumably because the acetylenic diol compound acts on the improvement in dispersibility of the water-insoluble crosslinking agent in the acrylic pressure-sensitive adhesive composition and the leveling effect when forming the pressure-sensitive adhesive layer. In addition, the said acetylene diol type compound can be used individually or in combination of 2 or more types.

上記式（Ｉ）中のＲ¹、Ｒ²、Ｒ³およびＲ⁴は、炭素数１〜２０の炭化水素基を表し、ヘテロ原子を含んでいてもよい。なお、Ｒ¹、Ｒ²、Ｒ³およびＲ⁴は、互いに同一であってもよいし、異なっていてもよい。
上記式（Ｉ）中のＲ¹、Ｒ²、Ｒ³およびＲ⁴は、直鎖状または分岐鎖状のいずれの構造であってもよい。 As said acetylene diol type compound, the compound represented by following formula (I) is mentioned, for example.

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 contain a hetero atom. R ¹ , R ² , R ³ and R ⁴ may be the same 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, in the above formula (I), R ¹ and R ⁴ are preferably an alkyl group having 2 to 10 carbon atoms, particularly an n-butyl group, sec-butyl group, tert-butyl group, isobutyl group having 4 carbon atoms. Is preferred. R ² and R ³ 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 acetylenic diol 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, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol and the like.

  Further, when the acetylene diol compound represented by the above formula (I) is blended in the preparation of the acrylic pressure-sensitive adhesive composition of the present invention, various acetylenic diol compounds represented by the above formula (I) are used. Those dispersed or dissolved in a solvent may be used. Examples of such a solvent include 2-ethylhexanol, butyl cellosolve, dipropylene glycol, ethylene glycol, propylene glycol, normal propyl alcohol, and isopropanol. Among these, ethylene glycol and propylene glycol are preferable from the viewpoint of dispersibility in the emulsion system. Further, the solvent content with respect to a dispersion (100 wt%) of the acetylenic diol compound in the solvent at the time of blending is less than 40 wt% (for example, 15 to 35 wt%) when ethylene glycol is used as the solvent. %) Is preferable, and when propylene glycol is used as a solvent, it is preferably less than 70% by weight (for example, 20 to 60% by weight).

  The acetylene diol compound represented by the above formula (I) may be a commercially available product. As such a commercial item, the Surfynol 104 series made from an air products company is mentioned, for example. More specifically, “Surfinol 104E”, “Surfinol 104H”, “Surfinol 104A”, “Surfinol 104BC”, “Surfinol 104DPM”, “Surfinol 104PA”, “Surfinol 104PG-50”, etc. Is mentioned.

上記式（ＩＩ）中のＲ⁵、Ｒ⁶、Ｒ⁷およびＲ⁸は、炭素数１〜２０の炭化水素基を表し、ヘテロ原子を含んでいてもよい。なお、Ｒ⁵、Ｒ⁶、Ｒ⁷およびＲ⁸は、互いに同一であってもよいし、異なっていてもよい。また、上記式（ＩＩ）中のｐ及びｑは０以上の整数であり、ｐとｑの和［ｐ＋ｑ］は１以上であり、１〜２０が好ましく、より好ましくは１〜９である。なお、ｐ及びｑは、互いに同一であってもよいし、異なっていてもよい。ｐ及びｑは、アセチレンジオール系化合物（Ｃ）のＨＬＢ値が１３未満になるように調整される数である。また、ｐが０の場合［−Ｏ−（ＣＨ₂ＣＨ₂Ｏ）pＨ］は水酸基［−ＯＨ］であり、ｑについても同じである。 Furthermore, as said acetylene diol type compound, the compound represented by following formula (II) is mentioned, for example.

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 contain 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 such that the HLB value of the acetylenic diol compound (C) is less than 13. When p is 0, [—O— (CH ₂ CH ₂ O) pH] 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 acetylenic diol compound represented by the above formula (II) include, for example, an ethylene oxide adduct of 7,10-dimethyl-8-hexadecin-7,10-diol, and 4,7-dimethyl-5-decyne. Ethylene oxide adduct of -4,7-diol, ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6- Examples thereof include ethylene oxide adducts of diols. 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.

  P and q in the formula (II) are numbers adjusted so that the HLB value of the acetylenic diol compound is less than 13. For example, when the acetylenic diol compound represented by the above formula (II) is an ethylene oxide adduct of 2,4,7,9-tetramethyl-5-decyne-4,7-diol, The total is preferably 9 or less.

The manufacturing time of the acrylic adhesive composition of the present invention, in formulating the ethylene oxide addition acetylenic diol compound of the acetylene diol compound represented by the formula (II), the mixing only a compound without solvent However, for the purpose of improving the blending workability, those obtained by dispersing or dissolving the above acetylenic diol compound 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, ethylene glycol and propylene glycol are preferably used from the viewpoint of dispersibility in an emulsion system.

  The acetylene diol compound represented by the above formula (II) may be a commercially available product. Examples of such commercially available products include Surfynol 400 series manufactured by Air Products. More specifically, “Surfinol 420”, “Surfinol 440” and the like can be mentioned.

  The acetylene diol compound has an HLB value (sometimes simply referred to as “HLB”) of less than 13, preferably 1 to 10, more preferably 3 to 8, and further preferably 3 to 5. When the HLB value is 13 or more, the contamination of the adherend is deteriorated. 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. Cometic Chemists, 1, 311 (1949), Koshimin Takahashi, Yoshiro Namba, Motoko Koike, Masao Kobayashi, “Surfactant Handbook”, 3rd edition, Engineering Books Co., Ltd., November 25, 1972 , P179-182 and the like.

The content of the acetylenic diol compound in the acrylic pressure-sensitive adhesive composition of the present invention is not particularly limited, but is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer. Preferably it is 0.1-7 weight part, More preferably, it is 0.5-5 weight part. When the content of the acetylenic diol compound is 0.01 parts by weight or more, it is preferable because an appearance defect due to a dent defect of the water-insoluble crosslinking agent can be effectively suppressed. Moreover, it is preferable that the content of the acetylenic diol compound is 10 parts by weight or less because contamination of the adherend by the acetylenic diol compound can be effectively suppressed.

(Ether group-containing polysiloxane)
The acrylic pressure-sensitive adhesive composition of the present invention contains at least an ether group-containing polysiloxane. The ether group-containing polysiloxane is a polysiloxane having an ether bond in a molecule (in one molecule). In addition, the said ether group containing polysiloxane can be used individually or in combination of 2 or more types.

  Since the acrylic pressure-sensitive adhesive composition of the present invention contains an ether group-containing polysiloxane, the pressure-sensitive adhesive force between the pressure-sensitive adhesive layer and the adherend increases with time in the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition. Therefore, good pick-up property can be obtained in the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition. This is presumably because the ether group-containing polysiloxane is likely to bleed out to the surface of the pressure-sensitive adhesive layer while suppressing an increase in the adhesive strength over time.

上記式（ＩＩＩ）中のＲ⁹は１価の有機基を表し、Ｒ¹⁰、Ｒ¹¹及びＲ¹²はアルキレン基を表し、Ｒ¹³は水酸基又は有機基を表す。ｍは、０〜１０００の整数である。ｎは、１〜１０００の整数である。ａ及びｂは０〜１００の整数であり、ａとｂは同時に０となることはない。 As said ether group containing polysiloxane, the compound represented by following formula (III) is mentioned preferably, for example.

R ⁹ in the above formula (III) represents a monovalent organic group, R ¹⁰ , R ¹¹ and R ¹² represent an alkylene group, and R ¹³ represents a hydroxyl group or an organic group. m is an integer of 0 to 1000. n is an integer of 1-1000. a and b are integers of 0 to 100, and a and b are not 0 at the same time.

Preferred examples of R ⁹ include alkyl groups such as a methyl group, an ethyl group, and a propyl group; aryl groups such as a phenyl group and a tolyl group; or a benzyl group; a phenethyl group. R ⁹ may be a monovalent organic group containing a substituent such as a hydroxyl group.
Moreover, as said R < ¹⁰ >, R < ¹¹ > and R < ¹² >, C1-C8 alkylene groups, such as a methylene group, ethylene group, a propylene group, are mentioned preferably. R ¹⁰ , R ¹¹ and R ¹² may contain a substituent such as a hydroxyl group.
Furthermore, when R ¹³ is an organic group, R ¹³ is preferably a monovalent organic group (for example, an alkyl group such as a methyl group or a propyl group, or an acyl group such as an acetyl group or a propionyl group). Or a monovalent organic group containing a substituent such as a hydroxyl group.

  The ether group-containing polysiloxane may have a reactive substituent such as a (meth) acryloyl group, an allyl group, or a hydroxyl group in the molecule.

The acrylic pressure-sensitive adhesive composition of the present invention contains at least an acrylic emulsion-based polymer, a water-insoluble crosslinking agent, an acetylenic diol compound, and an ether group-containing polysiloxane, but in the acrylic pressure-sensitive adhesive composition of the present invention. The content of the ether group-containing polysiloxane is such that the content of the water-insoluble crosslinking agent is X parts by weight with respect to 100 parts by weight of the chloremulsion polymer, and the content of the ether group-containing polysiloxane is an acrylic emulsion. When it is set to Y parts by weight with respect to 100 parts by weight of the polymer, it is an amount such that the value (A) obtained by the following formula (1) is 3 or more.
Value (A) = X + (Y × 3) (1)
When the content of the ether group-containing polysiloxane in the acrylic pressure-sensitive adhesive composition of the present invention is such an amount that the value (A) obtained by the formula (1) is less than 3, it is in a trade-off relationship. This is because it is impossible to obtain both characteristics of a certain pickup property and curl adjustment at the same time.

Specifically, the content of the ether group-containing polysiloxane is preferably 0.01 to 1.0 part by weight, more preferably 0.05 to 100 parts by weight of the acrylic emulsion polymer. It is -0.8 weight part, More preferably, it is 0.16-0.50 weight part. When the content of the ether group-containing polysiloxane is 0.01 parts by weight or more, it is possible to prevent the adhesive force between the adhesive layer formed from the adhesive composition and the adherend from increasing with time. In the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, good pick-up properties are easily obtained, which is preferable. Further, when the content of the ether group-containing polysiloxane is 1.0 part by weight or less, it is effective that the ether group-containing polysiloxane causes contamination in the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition. This is preferable because it can be prevented.

(Other additives)
The acrylic pressure-sensitive adhesive composition of the present invention contains various additives (components other than the water-insoluble crosslinking agent, acetylenic diol compound, and ether group-containing polysiloxane) as long as the effects of the present invention are not impaired. Also good. Examples of the various additives include pigments, fillers, dispersants, plasticizers, stabilizers, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, anti-aging agents, and antiseptics. In addition, such an additive can be used individually or in combination of 2 or more types.

  The acrylic pressure-sensitive adhesive composition of the present invention can be prepared by mixing the acrylic emulsion polymer, the water-insoluble crosslinking agent, the acetylenic diol compound, and the ether group-containing polysiloxane. In addition, said other additive may be mix | blended as needed. The mixing method may be a known and common emulsion mixing method, 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 2500 rpm, more preferably 30 to 2000 rpm.

  The acrylic pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer that can exhibit good pickup properties and can exhibit good curl adjustability. In addition, it is good for an adherend having a low polarity surface such as an optical member having a low polarity surface, and also for an adherend having a high polarity surface such as an optical member having a high polarity surface. It is possible to form an adhesive layer that can exhibit pick-up properties and can exhibit good curl adjustment. Furthermore, it has excellent removability, is excellent in environmental aspects, and can form a low-staining adhesive layer.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having at least a pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention. The pressure-sensitive adhesive sheet of the present invention may be a pressure-sensitive adhesive sheet with a base material having a pressure-sensitive adhesive layer on at least one surface side of the base material, or may be a base-less pressure-sensitive adhesive sheet composed only of a pressure-sensitive adhesive layer. . In particular, since the pressure-sensitive adhesive sheet of the present invention is preferably used for surface protection as described later, it is preferably a pressure-sensitive adhesive sheet with a substrate, more preferably a pressure-sensitive adhesive layer on one surface side of the substrate. It is preferable that it is a single-sided adhesive sheet with a base material which has.

  The pressure-sensitive adhesive sheet of the present invention may be a single-sided pressure-sensitive adhesive sheet or a double-sided pressure-sensitive adhesive sheet. Moreover, the adhesive sheet of this invention may have the lamination | stacking form which the adhesive sheet laminated | stacked, and may have the form wound by roll shape.

  The pressure-sensitive adhesive sheet of the present invention is produced by forming a pressure-sensitive adhesive layer by a known or conventional method using the acrylic pressure-sensitive adhesive composition of the present invention. For example, the single-sided pressure-sensitive adhesive sheet with the base material forms the pressure-sensitive adhesive layer by applying the acrylic pressure-sensitive adhesive composition of the present invention to at least one side of the base material, providing a coating layer, and drying by heating. (Direct copy method). Moreover, the said single-sided adhesive sheet with a base material is produced by once providing an adhesive layer on a peeling liner, and transferring the said adhesive layer to the at least single side | surface side of a base material (transfer method). In addition, you may perform further heating after a heat drying process as needed. For example, in order to increase the degree of crosslinking, the pressure-sensitive adhesive sheet may be heated after dehydration and drying in the drying step. Especially, it is preferable that the said single-sided adhesive sheet with a base material is produced by what is called a direct copy method. This is because the transfer method may not provide sufficient anchoring properties (adhesion) with the substrate.

  The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention (particularly the pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention) is not particularly limited, but is preferably 1 to 50 μm, more preferably 1 to 35 μm. More preferably, it is 3 to 25 μm.

The solvent-insoluble content (gel fraction) of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention (particularly the pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention) is not particularly limited, but is 90% (weight%) ) Or more, more preferably 95% by weight or more. When the solvent insoluble content is 90% by weight or more, it is possible to further suppress whitening contamination caused by an increase in the transfer of contaminants to the adherend and insufficient removability (heavy release), which is preferable.
In addition, the solvent insoluble content of the said adhesive layer can be measured by the method similar to the measuring method of the solvent insoluble content of the above-mentioned acrylic emulsion type polymer. Specifically, it can be measured by a method in which “acrylic emulsion polymer” is read as “pressure-sensitive adhesive layer” in the above-mentioned “method for measuring solvent insolubles”.

  The glass transition temperature of the base polymer (acrylic polymer) in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention (particularly the pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention) is not particularly limited, -70--10 degreeC is preferable, More preferably, it is -70--20 degreeC, More preferably, it is -70--40 degreeC. It is preferable that the glass transition temperature is −10 ° C. or lower because it is possible to further suppress the occurrence of floating and peeling during processing due to insufficient adhesive force. Moreover, it is preferable that it is -70 degreeC or more because it can suppress that it will carry out heavy peeling in a higher peeling speed (tensile speed) area | region and work efficiency will fall. The glass transition temperature of the polymer forming the adhesive layer can be adjusted, for example, by the monomer composition when preparing the acrylic emulsion polymer.

  Although it does not specifically limit as a base material in case the adhesive sheet of this invention is an adhesive sheet with a base material, From a viewpoint from which the adhesive sheet which has high transparency is obtained, a plastic substrate (for example, a plastic film and a plastic sheet) Is preferred. 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 triacetylcellulose are preferred. These resins may be used alone or in combination of two or more. Of these, polyester resins and polyolefin resins are preferable, and polyethylene terephthalate, polypropylene, and polyethylene are more preferable in terms of productivity and moldability. 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 thing 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. In addition, although the thickness of the said base material is not specifically limited, 10-150 micrometers is preferable, More preferably, it is 30-100 micrometers.

  Further, 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 this intermediate layer is preferably 0.01 to 1 μm, for example, and more preferably 0.1 to 1 μm.

  In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer surface (pressure-sensitive adhesive surface) may be protected by a release liner (separator). Moreover, the adhesive sheet of this invention can be made into a wound body as mentioned above, and can be wound up in roll shape in the state which protected the adhesive layer with the release liner. Furthermore, when the pressure-sensitive adhesive sheet of the present invention is a single-sided pressure-sensitive adhesive sheet with a substrate, the back surface of the substrate of the pressure-sensitive adhesive sheet (the surface opposite to the side where the pressure-sensitive adhesive layer is provided) is silicone-based, fluorine-based, A long-chain alkyl-based or fatty acid amide-based release agent, silica powder or the like is used for release treatment and / or antifouling treatment, and a back treatment layer (release treatment layer, antifouling treatment layer, etc.) is provided. Also good. And the form which makes it a wound body and protects an adhesion surface with the back surface of a base material may be sufficient. The pressure-sensitive adhesive sheet of the present invention may have a laminated form of pressure-sensitive adhesive layer / base material / back treatment layer.

  Adhesive strength of the pressure-sensitive adhesive sheet of the present invention (23 ° C., 50% RH environment, tensile speed 0.3 m / min, 180 ° peeling) (particularly pressure-sensitive adhesive layer formed from the acrylic pressure-sensitive adhesive composition of the present invention) Is not particularly limited, but is preferably 0.035 N / 25 mm or less, more preferably 0.030 N from the viewpoint of obtaining good removability and good pick-up property. / 25 mm or less. The lower limit of the adhesive strength is not particularly limited, but is preferably 0.010 N / 25 mm or more, more preferably 0.015 N / second from the viewpoint of suppressing the lifting and peeling of the adhesive sheet from the adherend. It is 25 mm or more.

  In particular, the pressure-sensitive adhesive strength of the pressure-sensitive adhesive sheet of the present invention does not depend on the polarity of the surface, that is, whether the surface is low polarity or high polarity, an optical member (an optical member described later, such as a polarizing plate). From the point of obtaining good removability and good pick-up property, it is preferably 0.035 N / 25 mm or less, more preferably 0.030 N / 25 mm or less. Moreover, the minimum of the said adhesive force is although it does not specifically limit, It is preferable that it is 0.010N / 25mm or more, More preferably, it is 0.015N / 25mm or more. Note that when the adhesive strength is 0.035 N / 25 mm or less, the adhesive sheet is difficult to peel off in the manufacturing process of an optical member or a product using the optical member (for example, a polarizing plate or a liquid crystal display device), and productivity is increased. The problem that the handleability is lowered is less likely to occur, which is preferable. In addition, when it is 0.010 N / 25 mm or more, it is easy to suppress the problem that the pressure-sensitive adhesive sheet is lifted or peeled off in the manufacturing process of the optical member or a product using the optical member (for example, a polarizing plate or a liquid crystal display device). It is preferable.

  Further, in the pressure-sensitive adhesive sheet of the present invention, “initial pressure-sensitive adhesive strength” (adhesive strength of the pressure-sensitive adhesive sheet immediately after production) is obtained from the viewpoint of obtaining good anti-adhesive strength preventing property and obtaining good removability and good pickup characteristics. And “adhesive strength after storage at 40 ° C. for 3 days” (adhesive strength of the adhesive sheet stored for 3 days in an environment of 40 ° C. after production) is preferably 0.035 N / 25 mm or less, more preferably 0.030 N / 25 mm or less.

  Since the pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer formed from the above-mentioned acrylic pressure-sensitive adhesive composition of the present invention, it can exhibit good pick-up properties and can exhibit good curl adjustability. Moreover, even if the sticking surface is low polarity or high polarity, good pick-up property can be exhibited and good curl adjustment property can be exerted on the adherend.

  In addition, since the pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer formed from the above-mentioned acrylic pressure-sensitive adhesive composition of the present invention, it has good removability, is excellent in environmental aspects, and is attached to an adherend. Even if it does not cause contamination such as whitening contamination, it is excellent in low contamination.

  The adhesive sheet of the present invention is used for re-peeling [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 sandblasting, etc. Surface protective film for aluminum sash, surface protective film for optical plastic, surface protective film for optical glass, surface protective film for automobile, surface protective film for metal plate, back grind tape, pellicle fixing tape , Dicing tape, lead frame fixing tape, cleaning tape, dust removal tape, carrier tape, cover tape and other semiconductor / electronic parts manufacturing process adhesive tape, electronic equipment and electronic parts packaging tape, Temporary fixing tapes, Tapes for bundles, are preferably used in the label such], and the like.

  In particular, the pressure-sensitive adhesive sheet of the present invention has excellent curl adjustability and can suppress the occurrence of curling when it is attached to an adherend. Moreover, even if the sticking surface has a low polarity or a high polarity, good pick-up property can be exhibited, and furthermore, the low contamination property is excellent. For this reason, the pressure-sensitive adhesive sheet of the present invention comprises a polarizing plate, a retardation plate, an antireflection plate, a wave plate, an optical compensation film, and a luminance improvement that constitute panels such as liquid crystal displays, organic electroluminescence (organic EL), and field emission displays. It is preferably used as a surface protection application (surface protection film for optical members, etc.) of optical members such as films (optical plastic, optical glass, optical film, etc.). 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.

[Optical member]
The optical member of the present invention has a structure to which the above adhesive sheet is attached. That is, the optical member of the present invention has a laminated structure of the optical member and the pressure-sensitive adhesive sheet of the present invention.

  Since the above-mentioned pressure sensitive adhesive sheet is stuck on the surface, the optical member of the present invention has the structure where the surface is protected by the pressure sensitive adhesive sheet. For this reason, scratches and cracks are unlikely to occur on the surface. In addition, since the pressure-sensitive adhesive sheet can serve as a mount or a supporting base material, excellent workability is exhibited during processing such as cutting.

  In addition, since the optical member of the present invention has a laminated structure with the pressure-sensitive adhesive sheet of the present invention that is excellent in curl adjustability, the occurrence of curling is suppressed. For this reason, process defects are unlikely to occur in a process of manufacturing a product using an optical member (for example, a liquid crystal panel). Thus, the optical member of the present invention contributes to an improvement in the yield of products in which the optical member is used. Furthermore, since the pressure-sensitive adhesive sheet attached to the optical member of the present invention is excellent in pick-up property from the optical member, the optical member of the present invention exhibits good workability. This also contributes to an improvement in the yield of products using the optical member.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Examples and Comparative Examples (Preparation of acrylic emulsion polymer)
In a container, 90 parts by weight of water and the raw material monomer of the blending amount shown in Table 1, a reactive surfactant (made by Daiichi Kogyo Seiyaku Co., Ltd., trade name “AQUALON HS-1025, radical polymerizable functional group in the molecule” After adding a reactive emulsifier having a group, the mixture was stirred and mixed with a homomixer to prepare a monomer emulsion.
Next, in a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 50 parts by weight of water, 0.01 part by weight of a polymerization initiator (ammonium persulfate), and 10% of the monomer emulsion prepared above %, And emulsion polymerization was carried out at 75 ° C. for 1 hour while stirring. Thereafter, 0.07 part by weight of a polymerization initiator (ammonium persulfate) was further added, and then all of the remaining monomer emulsion (amount corresponding to 90% by weight) was added over 3 hours with stirring. The reaction was carried out at 0 ° 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: 41% by weight) was obtained. Prepared.

(Preparation of water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling)
It is a water-insoluble crosslinking agent in the amount shown in Table 1 with respect to 244 parts by weight of the aqueous dispersion (41% by weight) of the acrylic emulsion polymer obtained above (100 parts by weight of the acrylic emulsion polymer). Epoxy crosslinking agent (Mitsubishi Gas Chemical Co., Ltd., trade name “Tetrad-C”, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, number of functional groups: 4), Table 1 The acetylene diol compound (composition) having an HLB value of 4 in the amount shown in (1) (product name “Surfinol 420”, active ingredient 100% by weight, manufactured by Air Products), ether group-containing poly in the amount shown in Table 1 Siloxane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “modified silicone oil KF-353”), the amount of ethylene oxide / propylene oxide copolymerization boundary shown in Table 1 A surfactant (trade name “Adeka Pluronic 25R-1” manufactured by ADEKA Co., Ltd.) was stirred and mixed using a stirrer at 23 ° C., 2000 rpm for 10 minutes, and then a water-dispersed acrylic adhesive for re-peeling. A composition was prepared.
In Table 1, “-” indicates that it was not used.

(Formation of adhesive layer, production of adhesive sheet)
Furthermore, the water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling obtained above is made on a corona-treated surface of a PET film (product name “E7415”, thickness: 38 μm, manufactured by Toyobo Co., Ltd.), manufactured by Tester Sangyo Co., Ltd. Using an applicator, apply so that the thickness after drying is 20 μm, then dry in a hot air circulating oven at 120 ° C. for 2 minutes, and then age at 23 ° C. for 5 days (aging) to form an adhesive sheet Obtained.

Evaluation About the adhesive sheet obtained by the Example and the comparative example, it evaluated by the following measuring method or evaluation method. The results are shown in Table 1.

Adhesive strength (initial adhesive strength)
A sheet-like measurement sample having a width of 25 mm and a length of 100 mm was obtained from the adhesive sheet. Next, the measurement sample is bonded to a plate-shaped adherend using a bonding machine (manufactured by Tester Sangyo Co., Ltd., a small bonding machine) under the conditions of 0.26 MPa and 0.3 m / min. It was. Then, it was left for 30 minutes in an environment of 23 ° C. and 50% RH.
After standing, using a tensile tester, a 180 ° peel test was performed at a tensile rate of 0.3 m / min in an environment of 23 ° C. and 50% RH, and the adhesive force (peel force) (N / 25 mm) was measured. . The adhesive strength was defined as “initial adhesive strength”.
As the adherend, a polarizing plate (trade name “SEG1425DU”, manufactured by Nitto Denko Corporation, surface is highly polar, triacetyl cellulose polarizing plate) (sometimes simply referred to as “high polarity surface polarizing plate”), In addition, a polarizing plate made of triacetyl cellulose having a low polarity on the surface (antiglare coating treatment is applied to the surface) (sometimes simply referred to as “low polarity surface polarizing plate”) was used.
Regarding the obtained initial adhesive strength, the adhesive strength to the high polar surface polarizing plate is shown in the column of “Initial adhesive strength high polar surface polarizing plate” in Table 1, and the initial adhesive strength to the low polar surface polarizing plate is shown in Table 1. It is shown in the column of “Force Low Polarizing Plate”.

(Adhesive strength after storage at 40 ° C for 3 days)
A sheet-like measurement sample having a width of 25 mm and a length of 100 mm was obtained from the adhesive sheet. Next, the measurement sample is bonded to a plate-shaped adherend using a bonding machine (manufactured by Tester Sangyo Co., Ltd., a small bonding machine) under the conditions of 0.26 MPa and 0.3 m / min. It was. Then, after storing in an environment of 40 ° C. for 3 days, it was left in an environment of 23 ° C. and 50% RH for 2 hours.
After standing, using a tensile tester, a 180 ° peel test was performed at a tensile rate of 0.3 m / min in an environment of 23 ° C. and 50% RH, and the adhesive force (peel force) (N / 25 mm) was measured. . The adhesive strength was defined as “adhesive strength after storage at 40 ° C. for 3 days”.
As the adherend, the high-polarity surface polarizing plate and the low-polarity surface polarizing plate were used.
Regarding the adhesive strength after storage at 40 ° C. for 3 days, the adhesive strength to the high-polarity surface polarizing plate is shown in the column of “Adhesive strength after storage at 40 ° C. for 3 days High-polarity surface polarizing plate” in Table 1. The adhesive strength against is shown in the column of “Adhesive strength after storage at 40 ° C. for 3 days, low-polarity surface polarizing plate” in Table 1.

Pick-up property Adhesive sheet width 25mm, length 100mm, using a bonding machine (Small Bonding Machine manufactured by Tester Sangyo Co., Ltd.) under the conditions of 0.26MPa, 0.3m / min, width 40mm, length 40mm The plate-shaped adherend was bonded by pressure bonding. Then, it was left for 30 minutes in an environment of 23 ° C. and 50% RH.
After leaving, a masking tape (trade name “No. 720A”, Nitto Denko Corporation) was attached by hand near the corner of the edge of the adhesive sheet, and the masking tape was immediately pulled up.
The case where the adhesive sheet is peeled off from the adherend by pulling up the masking tape is evaluated as “good” (O). On the other hand, the case where the adhesive sheet is not peeled off from the adherend even when the masking tape is pulled up is evaluated as “ It was evaluated as “bad” (×).
As the adherend, the high-polarity surface polarizing plate and the low-polarity surface polarizing plate were used.
Regarding the pick-up property evaluated, the pick-up property for the high-polarity surface polarizing plate is shown in the column of “Pick-up property high-polarity surface polarizing plate” in Table 1, and the pick-up property for the low-polarity surface polarizing plate is shown in “Pick-up property low-polarity surface” in Table 1. It is shown in the column of “Polarizing plate”.

Curl controllability Adhesive sheet cut slightly larger than the above high-polarity surface polarizing plate is bonded to the above high-polarity surface polarizing plate (width 140 mm, length 200 mm, thickness 0.2 mm) placed on a metal plate. The length direction of the high-polarity surface polarizing plate and the length direction of the pressure-sensitive adhesive sheet are the same under the conditions of 0.26 MPa and 0.3 m / min using a machine (manufactured by Tester Sangyo Co., Ltd., a small laminating machine). I stuck together. In addition, in the case of bonding, it bonded together, pulling an adhesive sheet. After bonding, the pressure-sensitive adhesive sheet protruding from the high-polarity surface polarizing plate was cut. And the sample for evaluation which has the structure where the surface of the high polarity surface polarizing plate was protected by the adhesive sheet was obtained.
Next, the evaluation sample was placed on a flat surface, and the distance from the flat surface (distance in the height direction) was measured for each of the four corners. And the average value was calculated | required from these values, and the average value was made into the "initial curl height."
After obtaining the “initial curl height”, the sample for evaluation was left in an environment of 23 ° C. and 50% RH for 20 hours. After leaving, the sample for evaluation was placed on a flat surface, and the distance from the flat surface (the distance in the height direction) was measured for each of the four corners. And the average value was calculated | required from these values, and the average value was made into "the curl height after 20 hours."
The difference between the “initial curl height” and the “curl height after 20 hours” ([(initial curl height) − (curl height after 20 hours)]] is sometimes referred to as “difference between curl heights”. Asked). The case where the difference in curl height was 8 mm or more was evaluated as “good” (◯), while the case where it was less than 8 mm was evaluated as “bad” (◯).
Regarding the evaluated curl adjustability, “Initial curl height” is shown in the column of “Curl adjustability initial curl height” in Table 1, and “Curl height after 20 hours” is “Curl adjustability after 20 hours” in Table 1. The “curl height” column is shown, and the “curl height difference” is shown in the “curl adjustability curl height difference” column of Table 1.
In addition, when the curl adjustability is good, it is possible to adjust the curl in the optical member to which the pressure-sensitive adhesive sheet is attached, and to prevent the occurrence of process defects in the process of manufacturing a product using the optical member. On the other hand, if the curl adjustability is poor, the curl cannot be sufficiently adjusted in the optical member to which the adhesive sheet is attached, and a process failure may occur in the process of manufacturing a product using the optical member.

The abbreviations used in Table 1 are as follows. In Table 1, the compounding amount of each component of the acrylic pressure-sensitive adhesive composition is shown by the actual compounding amount (composition amount of the product). In addition, the acrylic emulsion type polymer was shown by the weight of solid content.
(Raw material monomer)
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate AA: acrylic acid (emulsifier)
HS-1025: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “AQUALON HS-1025” (reactive surfactant, reactive emulsifier having a radical polymerizable functional group in the molecule)
(Acetylene diol compounds)
Surfynol 420: Product name “Surfinol 420” (HLB value 4, active ingredient 100% by weight) manufactured by Air Products
(Water-insoluble crosslinking agent)
TETRAD-C: manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name “TETRAD-C (Tetrad-C)” (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, number of functional groups: 4 )
(Ether group-containing polysiloxane)
KF-353: Shin-Etsu Chemical Co., Ltd., trade name “modified silicone oil KF-353”
(Ethylene oxide / propylene oxide copolymer surfactant)
25R-1: Product name “Adeka Pluronic 25R-1” manufactured by ADEKA Corporation

Claims (6)

Containing an acrylic emulsion polymer, a water-insoluble crosslinking agent, an acetylenic diol compound and an ether group-containing polysiloxane,
The acrylic emulsion polymer is composed of (meth) acrylic acid alkyl ester and carboxyl group-containing unsaturated monomer as essential raw material monomers, and the content of (meth) acrylic acid alkyl ester is based on the total amount of raw material monomers. 70 to 99.5% by weight, and the content of the carboxyl group-containing unsaturated monomer is 0.5 to 10.0% by weight with respect to the total amount of raw material monomers,
Wherein the non-content of the water-soluble crosslinking agent is X parts by weight relative to the acrylic emulsion polymer to 100 parts by weight, the content of the ether group-containing polysiloxane to said acrylic emulsion polymer to 100 parts by weight A water-dispersed acrylic pressure-sensitive adhesive for re-peeling, characterized in that it is Y parts by weight, the X is 1.5 or more, and the value (A) determined by the following formula (1) is 3 to 4.18 Composition.
Value (A) = X + (Y × 3) (1)   The water-dispersible acrylic pressure-sensitive adhesive composition for re-peeling according to claim 1, wherein the acrylic emulsion polymer is a polymer polymerized using a reactive emulsifier having a radical polymerizable functional group in the molecule.   The water-dispersible acrylic pressure-sensitive adhesive for re-peeling according to claim 1 or 2, wherein the content of the water-insoluble crosslinking agent is 2.15 to 3.0 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer. Composition.   The water for re-peeling according to any one of claims 1 to 3, wherein the content of the ether group-containing polysiloxane is 0.16 to 0.50 parts by weight with respect to 100 parts by weight of the acrylic emulsion polymer. Dispersed acrylic pressure-sensitive adhesive composition.   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 any one of claims 1 to 4.   An optical member, wherein the pressure-sensitive adhesive sheet according to claim 5 is attached.