JP2013216758A - Aqueous dispersion type acrylic adhesive composition, adhesive sheet, and optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersion type acrylic adhesive composition formable of an adhesive layer excellent in antistaticity against peeling, removability and adhesiveness (tackiness); an adhesive sheet having an adhesive layer of the adhesive composition; a production method of the adhesive sheet.SOLUTION: An aqueous dispersion type acrylic adhesive composition comprises an acrylic emulsion-based polymer including, as raw material monomers, at least alkyl (meth)acrylate (A), 0.5-10 wt.% of carboxy group-containing unsaturated monomer (B) and a non-reactive quaternary ammonium salt type surfactant having two or less methyl group.

Description

  The present invention relates to a water-dispersed acrylic pressure-sensitive adhesive composition capable of forming a re-peelable pressure-sensitive adhesive layer. Specifically, the present invention relates to a water-dispersed acrylic pressure-sensitive adhesive composition that can form a pressure-sensitive adhesive layer excellent in peeling antistatic properties, re-peeling properties, and adhesiveness (tackiness). The present invention also relates to a pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition, and an optical member using the pressure-sensitive adhesive sheet.

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

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

  These surface protective films are required to exhibit sufficient adhesiveness while being attached to the optical member. Furthermore, since it peels after using in the manufacturing process of an optical member, etc., the outstanding peelability (removability) is calculated | required.

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

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

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

  However, as described above, none of the above problems can still be solved in a balanced manner, and in a technical field related to electronic equipment in which charging or the like is a particularly serious problem, it is possible to further improve the surface protection film having anti-peeling property and the like. It is difficult to meet the demand for improvement, and a water-dispersed acrylic pressure-sensitive adhesive having removability and adhesiveness (tackiness) has not been obtained at present.

  Accordingly, an object of the present invention is to provide a water-dispersed acrylic pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in peeling antistatic properties, re-peelability, and adhesiveness (tackiness). It is in. Moreover, it is providing the adhesive sheet which has an adhesive layer by the said adhesive composition, and its manufacturing method.

  As a result of intensive studies to achieve the above object, the present inventors have found that a specific acrylic emulsion polymer obtained from a raw material monomer having a specific composition, and a specific non-reactive quaternary quaternary that does not participate in emulsion (emulsion) polymerization. A water-dispersed acrylic pressure-sensitive adhesive composition that can form a pressure-sensitive adhesive sheet comprising an ammonium salt-type surfactant as a constituent component and excellent in peeling antistatic properties and pressure-sensitive adhesive properties (removability and adhesion (stickiness)) Was found and the present invention was completed.

  That is, the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention contains at least (meth) acrylic acid alkyl ester (A) and carboxyl group-containing unsaturated monomer (B) as a raw material monomer in an amount of 0.5 to 10%. It contains an acrylic emulsion polymer containing% by weight and a non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups.

  In the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention, the surfactant is preferably composed of an anion and a cation, and the anion and / or the cation preferably contains an alkylene oxide group.

  In the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention, the (meth) acrylic acid alkyl ester (A) preferably has an alkyl group having 2 to 14 carbon atoms.

  The water-dispersed acrylic pressure-sensitive adhesive composition of the present invention preferably further contains an alkylene oxide group-containing polysiloxane.

  In the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention, the polysiloxane preferably has an HLB value of 4 to 12.

  In the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention, the polysiloxane is preferably composed of at least an ethylene oxide (EO) group.

  In the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention, the polysiloxane contains a propylene oxide (PO) group, and the molar content of the PO is 100% relative to the total molar content of the EO and PO. 50% or less is preferable.

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

  The pressure-sensitive adhesive sheet of the present invention has a peeling force (peeling speed 30 m / min) of 1 N / 25 mm or less when the pressure-sensitive adhesive layer is attached to a polarizing plate (manufactured by Nitto Denko Corporation, trade name: SEG1425DU). Is preferred.

  The optical member of the present invention is preferably formed by attaching the pressure-sensitive adhesive sheet.

  The water-dispersed acrylic pressure-sensitive adhesive composition of the present invention includes a specific acrylic emulsion polymer obtained from a raw material monomer having a specific composition, and a specific non-reactive quaternary ammonium salt type not involved in emulsion (emulsion) polymerization. A surfactant layer is used as a constituent component, and a pressure-sensitive adhesive layer and a pressure-sensitive adhesive sheet excellent in peeling antistatic properties and pressure-sensitive adhesive properties (removability and adhesion (tackiness)) can be obtained and are useful.

Schematic diagram of potential measurement unit

  The water-dispersed acrylic pressure-sensitive adhesive composition of the present invention contains at least 0.5 to 10% by weight of (meth) acrylic acid alkyl ester (A) and carboxyl group-containing unsaturated monomer (B) as raw material monomers. And an acrylic emulsion-based polymer containing 2 and a non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups.

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

  The said (meth) acrylic-acid alkylester (A) is used as a main monomer component, and mainly plays the role which expresses the basic characteristics as adhesives (or adhesive layer), such as adhesiveness and peelability. Among them, acrylic acid alkyl esters tend to give flexibility to the polymer forming the pressure-sensitive adhesive layer, and exhibit the effect of developing adhesiveness and adhesiveness to the pressure-sensitive adhesive layer. There exists a tendency which gives the polymer to form hardness and exhibits the effect which adjusts the removability of an adhesive layer. The (meth) acrylic acid alkyl ester (A) is not particularly limited, but is linear, branched or cyclic having 2 to 14 carbon atoms (more preferably 2 to 10 and more preferably 4 to 8). And (meth) acrylic acid alkyl esters having the following alkyl groups.

  Among them, as the alkyl acrylate ester, for example, an alkyl acrylate ester having an alkyl group having 2 to 14 carbon atoms (more preferably 4 to 9) is preferable, such as n-butyl acrylate, isobutyl acrylate, acrylic acid s. -It has a linear or branched alkyl group such as butyl, isoamyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, nonyl acrylate, or isononyl acrylate. Examples include acrylic acid alkyl esters. Of these, 2-ethylhexyl acrylate is preferable.

  Further, as the alkyl methacrylate, for example, an alkyl methacrylate having an alkyl group having 2 to 14 carbon atoms (more preferably 2 to 10) is preferable, such as ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, methacrylic acid. Methacrylic acid alkyl ester having a linear or branched alkyl group such as n-butyl acid, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, bornyl methacrylate, isobornyl methacrylate And an alicyclic methacrylic acid alkyl ester.

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

  Content of the said (meth) acrylic-acid alkylester (A) is 70-99.5 weight% in the total amount (total raw material monomer) (100 weight%) of the raw material monomer which comprises the acrylic emulsion type polymer of this invention. Is preferable, more preferably 85 to 98% by weight, and particularly preferably 87 to 95% by weight. It is preferable that the content is 70% by weight or more because the adhesive properties (adhesiveness, removability, etc.) of the adhesive layer are improved. On the other hand, when the content exceeds 99.5% by weight, the appearance of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition may deteriorate due to a decrease in the content of the carboxyl group-containing unsaturated monomer (B). is there. In addition, when 2 or more types of (meth) acrylic-acid alkylesters (A) are used, the total amount (total amount) of all the (meth) acrylic-acid alkylesters (A) should just satisfy the said range. .

  The said carboxyl group-containing unsaturated monomer (B) can exhibit the function which forms a protective layer on the emulsion particle | grain surface which consists of an acrylic emulsion type polymer of this invention, and prevents the shear fracture | rupture of particle | grains. This effect is further improved by neutralizing the carboxyl group with a base. The stability of the particles against shear fracture is more generally referred to as mechanical stability. In addition, by combining one or two or more crosslinking agents that react with carboxyl groups (in the present invention, water-insoluble crosslinking agents are preferred), it also acts as a crosslinking point in the pressure-sensitive adhesive layer forming stage by water removal. You can also Furthermore, the adhesiveness (anchoring property) with a base material can also be improved through a crosslinking agent (water-insoluble crosslinking agent). As such a carboxyl group-containing unsaturated monomer (B), for example, (meth) acrylic acid (acrylic acid, methacrylic acid), itaconic acid, maleic acid, fumaric acid, crotonic acid, carboxyethyl acrylate, carboxypentyl acrylate, etc. Is mentioned. The carboxyl group-containing unsaturated monomer (B) 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.

  Content of the said carboxyl group-containing unsaturated monomer (B) is 0.5 to 10 weight% in the total amount (total raw material monomer) (100 weight%) of the raw material monomer which comprises the acrylic emulsion type polymer of this invention. Yes, preferably 1 to 6% by weight, more preferably 2 to 5% by weight. By controlling the content to 10% by weight or less, an increase in interaction with a functional group present on the surface of a polarizing plate or the like as an adherend (protected body) after the pressure-sensitive adhesive layer is formed is suppressed. Thus, it is preferable because an increase in peeling (adhesion) force with time can be suppressed and the peelability is improved. Further, when the content exceeds 10% by weight, the carboxyl group-containing unsaturated monomer (B) (for example, acrylic acid) is generally water-soluble, so it is polymerized in water and thickened (increased viscosity). May cause. In addition, when a large number of carboxyl groups are present in the skeleton of the acrylic emulsion polymer, it interacts with the ether group of the alkylene oxide group-containing polysiloxane blended as an antistatic agent, impeding ionic conduction, and adherend It is presumed that the antistatic performance against peeling to the surface cannot be obtained, which is not preferable. On the other hand, the content of 0.5% by weight or more is preferable because the mechanical stability of the emulsion particles is improved. Moreover, since the adhesiveness (throwing property) of an adhesive layer and a base material improves and adhesive residue can be suppressed, it is preferable.

  As the raw material monomer constituting the acrylic emulsion polymer of the present invention, for the purpose of imparting a specific function, the essential component [(meth) acrylic acid alkyl ester (A), carboxyl group-containing unsaturated monomer (B)] is used. In addition, at least one monomer (C) selected from the group consisting of methyl methacrylate, vinyl acetate, and diethyl acrylamide can be used in combination as a constituent component. When these monomers (at least one) are used, the stability of the emulsion particles is increased, the gel (aggregate) can be reduced, and the appearance defects can be reduced, which is effective. . In addition, when a water-insoluble cross-linking agent is used as the cross-linking agent, the affinity with the hydrophobic water-insoluble cross-linking agent is increased, and the dispersibility of the emulsion particles is improved. Can be reduced.

  The content of the monomer (C) is preferably from 0.5 to 10% by weight, more preferably from the total amount of raw material monomers (total raw material monomer) (100% by weight) constituting the acrylic emulsion polymer of the present invention. 1 to 6% by weight, particularly preferably 2 to 5% by weight. By making the content 10% by weight or less, appearance defects of the pressure-sensitive adhesive layer can be suppressed, which is preferable. Moreover, when content exceeds 10 weight%, an aggregate may be caused (it produces | generates). On the other hand, the content of 0.5% by weight or more is preferable because the mechanical stability of the emulsion particles is improved.

  In addition to the monomers (A) to (C), as another monomer component, an epoxy group-containing monomer such as glycidyl (meth) acrylate is used for the purpose of crosslinking in emulsion particles and improving cohesion. It is also possible to use a polyfunctional monomer such as trimethylolpropane tri (meth) acrylate or divinylbenzene. In addition, it is preferable to mix | blend (add) each in the ratio of less than 5 weight%. In addition, the said compounding quantity (use amount) is content in the total amount (total raw material monomer) (100 weight%) of the raw material monomer which comprises the acrylic emulsion type polymer of this invention.

  Further, as the other monomer component, the hydroxyl group-containing unsaturated monomer such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate has a smaller blending amount (amount used) from the viewpoint of reducing whitening contamination. preferable. Specifically, the blending amount of the hydroxyl group-containing unsaturated monomer (content in the total amount of raw material monomers (total raw material monomer) (100% by weight) constituting the acrylic emulsion polymer of the present invention) is 1% by weight. Is preferably less than, more preferably less than 0.1% by weight, even more preferably substantially free (eg, less than 0.05% by weight). However, when the purpose is to introduce a crosslinking point such as crosslinking between a hydroxyl group and an isocyanate group or metal crosslinking, about 0.01 to 10% by weight may be added (used).

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

[emulsifier]
As the emulsifier used for the emulsion polymerization of the acrylic emulsion polymer of the present invention, a reactive emulsifier having a radical polymerizable functional group introduced into the molecule (reactive emulsifier containing a radical polymerizable functional group) may be used. This is a preferred embodiment. The reactive emulsifier is used alone or in combination of two or more.

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

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

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

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

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

  The compounding amount (usage amount) of the reactive emulsifier is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of raw material monomers (total raw material monomers) constituting the acrylic emulsion polymer of the present invention, More preferably, it is 1-6 weight part, More preferably, it is 2-5 weight part. A blending amount of 0.1 part by weight or more is preferable because stable emulsification can be maintained. On the other hand, when the blending amount is 10 parts by weight or less, the cohesive force of the pressure-sensitive adhesive (pressure-sensitive adhesive layer) is improved, contamination to the adherend can be suppressed, and contamination by the emulsifier can be suppressed, which is preferable.

[Polymerization initiator]
The polymerization initiator used for emulsion polymerization of the acrylic emulsion polymer is not particularly limited. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride. 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'- Azo polymerization initiators such as azobis (N, N'-dimethyleneisobutylamidine); persulfates such as potassium persulfate and ammonium persulfate; peroxidations such as benzoyl peroxide, t-butyl hydroperoxide, and hydrogen peroxide Physical polymerization initiators; redox initiators in combination with peroxides and reducing agents, for example peroxides and Ascos Combinations with binoic acid (such as a combination of hydrogen peroxide and ascorbic acid), combinations of peroxide and iron (II) salt (such as a combination of hydrogen peroxide and iron (II) salt), persulfate A redox polymerization initiator based on a combination of a salt and sodium hydrogen sulfite can be used.

  The blending amount (use amount) of the polymerization initiator can be appropriately determined according to the type of the initiator and the raw material monomer, and is not particularly limited. However, the amount of the raw material monomer constituting the acrylic emulsion polymer of the present invention is not particularly limited. The amount is preferably 0.01 to 1 part by weight, more preferably 0.02 to 0.5 part by weight, based on 100 parts by weight of the total amount (total raw material monomers).

[Emulsion polymerization]
Emulsion polymerization (emulsion polymerization) of the acrylic emulsion-based polymer of the present invention can be performed by emulsifying the monomer component in water and then emulsion polymerization by a conventional method. Thereby, the aqueous dispersion (polymer emulsion) which contains the said acrylic emulsion type polymer as a base polymer can be prepared. The emulsion polymerization method is not particularly limited, and for example, a known emulsion polymerization method such as a batch charging method (batch polymerization method), a monomer dropping method, or a monomer emulsion dropping method can be employed. In the monomer dropping method and the monomer emulsion dropping method, continuous dropping or divided dropping is appropriately selected. These methods can be appropriately combined. Although reaction conditions etc. are selected suitably, it is preferable that polymerization temperature is about 40-95 degreeC, for example, and it is preferable that polymerization time is about 30 minutes-about 24 hours.

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

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

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

  The weight average molecular weight (Mw) of the solvent-soluble component (sometimes referred to as “sol component”) of the acrylic emulsion polymer of the present invention is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, More preferably, it is 60,000 to 100,000. When the weight average molecular weight of the solvent-soluble component of the acrylic emulsion polymer is 40,000 or more, the wettability of the pressure-sensitive adhesive composition to the adherend is improved, and the adhesion to the adherend is improved. In addition, since the weight average molecular weight of the solvent-soluble component of the acrylic emulsion polymer is 200,000 or less, the residual amount of the pressure-sensitive adhesive composition on the adherend is reduced, and the low contamination property to the adherend is improved. To do. The weight average molecular weight of the solvent-soluble component of the acrylic emulsion polymer is determined by air-drying the treated solution (ethyl acetate solution) after the ethyl acetate treatment obtained in the measurement of the solvent-insoluble component of the acrylic emulsion polymer at room temperature. The sample (solvent-soluble content of the acrylic emulsion polymer) obtained by the measurement can be obtained by measurement by GPC (gel permeation chromatography). Specific methods for measuring include the following methods.

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

[Crosslinking agent]
The pressure-sensitive adhesive composition of the present invention is more excellent in heat resistance by appropriately crosslinking an acrylic emulsion polymer, and is a preferred embodiment. Although it does not restrict | limit especially as a crosslinking agent used for this invention, For example, an isocyanate compound, an epoxy compound, a melamine type resin, an aziridine derivative, a metal chelate compound, etc. can be used. Among these, an isocyanate compound and an epoxy compound are particularly preferably used mainly from the viewpoint of obtaining an appropriate cohesive force. These compounds may be used alone or in combination of two or more.

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

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

  The water-insoluble crosslinking agent of the present invention is a water-insoluble compound. The term “water-insoluble” means that the solubility in 100 parts by weight of water at 25 ° C. (the weight of the compound (crosslinking agent) soluble in 100 parts by weight of water) is 5 parts by weight or less, preferably 4 It is 3 parts by weight or less, more preferably 3 parts by weight or less. By using a water-insoluble cross-linking agent, the cross-linking agent remaining without cross-linking is unlikely to cause whitening contamination generated on the adherend in a high-humidity environment, and the low-contamination property is improved. In the case of a water-soluble cross-linking agent, in a high humidity environment, the remaining cross-linking agent dissolves in water and is easily transferred to an adherend, and thus easily causes whitening contamination. Further, the water-insoluble cross-linking agent has a higher contribution to the cross-linking reaction (reaction with a carboxyl group) than the water-soluble cross-linking agent, and has a high effect of preventing the peeling (adhesion) force from increasing with time. Furthermore, since the water-insoluble cross-linking agent has high reactivity of the cross-linking reaction, the cross-linking reaction proceeds promptly by aging, and the peeling (adhesion) force from the adherend due to the unreacted carboxyl group in the pressure-sensitive adhesive layer is increased over time. Can be prevented from rising.

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

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

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

  The blending amount of the water-insoluble crosslinking agent of the present invention (content in the pressure-sensitive adhesive composition of the present invention) is that of the carboxyl group-containing unsaturated monomer (B) used as a raw material monomer of the acrylic emulsion polymer of the present invention. It is preferable that the amount of the functional group capable of reacting with the carboxyl group of the water-insoluble crosslinking agent of the present invention is 0.1 to 1.3 mol relative to 1 mol of the carboxyl group. That is, “all the water-insoluble cross-linking agents of the invention of the present invention relative to“ the total number of carboxyl groups of all carboxyl group-containing unsaturated monomers (B) used as raw material monomers of the acrylic emulsion polymer of the invention ””. The ratio of “the total number of moles of functional groups capable of reacting with carboxyl groups” [functional group capable of reacting with carboxyl groups / carboxyl groups] (molar ratio) is preferably 0.1 to 1.3, more preferably 0. .3 to 1.1. By setting [functional group / carboxyl group capable of reacting with carboxyl group] to 0.1 or more, unreacted carboxyl group in the pressure-sensitive adhesive layer is reduced, resulting from the interaction between the carboxyl group and the adherend. It is preferable because an increase in peeling (adhesion) force with time can be effectively prevented. Furthermore, since it becomes easy to control the solvent-insoluble part and breaking elongation of the acrylic adhesive film after bridge | crosslinking within the range prescribed | regulated by this invention, it is preferable. Moreover, by setting it as 1.3 or less, the unreacted water-insoluble cross-linking agent in the pressure-sensitive adhesive layer can be reduced, appearance defects due to the water-insoluble cross-linking agent can be suppressed, and the appearance characteristics can be improved. preferable.

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

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

[Non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups]
The water-dispersed acrylic pressure-sensitive adhesive composition of the present invention contains a non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups as an essential component, and the number of methyl groups is 1 or 2 Is preferred. The surfactant is blended (used) as an antistatic agent and plays a different role from the emulsifier used during emulsion (emulsion) polymerization. And after emulsion polymerization completion | finish, after mix | blending an acrylic emulsion type polymer, it mix | blends and uses it. By containing the surfactant, the obtained pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) is attached to an adherend (protected body), and then peeled off against an adherend that is not antistatic. , Peeling antistatic property can be imparted. Further, compatibility with the acrylic emulsion polymer and a balanced interaction can be expected.

  The non-reactive quaternary ammonium salt-type surfactant having 2 or less methyl groups of the present invention is not particularly limited. For example, as the non-reactive quaternary ammonium salt-type surfactant having one methyl group, Are polyoxypropylene methyldiethylammonium chloride, methyldiethyl (2-methoxyethyl) ammonium chloride, octylbispolyoxyethylenemethylammonium chloride, laurylbispolyoxyethylenemethylammonium chloride, oleylbispolyoxyethylenemethylammonium chloride, poly Examples of the non-reactive quaternary ammonium salt type surfactant having two methyl groups include aliphatic alkyl quaternary ammonium salts. Octyl dimethyl ethyl ammonium ethyl sulfate, lauryl dimethyl ethyl ammonium ethyl sulfate, palmityl dimethyl ethyl ammonium ethyl sulfate, didecyl dimethyl ammonium chloride, distearyl dimethyl ammonium chloride, lauryl dimethyl benzyl ammonium chloride, stearyl dimethyl hydroxyethyl ammonium paratoluene sulfonate, Alkyl benzyl dimethyl ammonium chloride, ethyl dimethyl (2-methoxyethyl) ammonium chloride, etc. are used suitably. Especially, it is preferable that the surfactant contains an alkylene oxide (AO) group. As the alkylene oxide group, those contained in either or both of an anionic component and a cationic component of the surfactant can be used. Examples of the alkylene oxide (AO) group-containing polyoxypropylene methyldiethylammonium chloride, methyldiethyl (2-methoxyethyl) ammonium chloride, octyl bispolyoxyethylene methylammonium chloride, lauryl bispolyoxyethylene The use of methylammonium chloride, oleyl bispolyoxyethylene methylammonium chloride, polyoxyethylene dodecyl monomethylammonium chloride, and ethyldimethyl (2-methoxyethyl) ammonium chloride is also a more preferred embodiment. These surfactants may be used alone or in combination of two or more.

  As the non-reactive quaternary ammonium salt type surfactant, a commercially available product can be used. For example, trade name “ADEKA COAL CC-36” (number of methyl groups: 1, manufactured by ADEKA Corporation), “ADEKA COAL CC-42 ”(number of methyl groups: 1, manufactured by ADEKA Corporation), trade name“ cationic L-207 ”(number of methyl groups: 1, manufactured by NOF Corporation), trade name“ Kathiogen ES-L ”( Number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Katiogen ES-O” (number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Katiogen ES-OW” ( Number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Katiogen ES-WS-L-9” (number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Katiogen ES” -P "(Methyl group number: 2, manufactured by Dai-ichi Kogyo) ), Trade name "Katiogen DDM-PG" (Methyl group number: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name "Katiogen S" (Methyl group number: 2, Daiichi Kogyo Seiyaku Co., Ltd.) ), Trade name "Katiogen D2" (number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), trade name "Katiogen BC-50" (number of methyl groups: 2, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Or the like can be used.

  About the compounding quantity of the said non-reactive quaternary ammonium salt type surfactant used for this invention, it is preferable to mix | blend 10 weight part or less with respect to 100 weight part of acrylic emulsion type polymers, 0.2-8 More preferably, it is blended in an amount of 0.5 to 6 parts by weight. If the amount exceeds 10 parts by weight, the contamination of the adherend (protected body) tends to increase, which is not preferable.

[Alkylene oxide group-containing polysiloxane (AO-containing polysiloxane)]
The water-dispersed acrylic pressure-sensitive adhesive composition of the present invention can further contain an alkylene oxide group-containing polysiloxane (AO-containing polysiloxane). By including the alkylene oxide group-containing polysiloxane, more excellent antistatic properties can be developed. Although the details of the mechanism by which peeling antistatic properties are manifested are not clear, since the alkylene oxide (AO) group has a high affinity with moisture in the air, charge transfer to the air easily occurs. The oxide group has a high degree of freedom of molecular motion, and it is presumed that excellent anti-release antistatic property is expressed because the charge generated at the time of peeling easily moves into the air efficiently. Since the polysiloxane skeleton has a high surface adsorptivity even with a small amount due to its low surface tension, it can be uniformly transferred to the surface of the adherend when the adhesive sheet is peeled off from the adherend (protected body). It is possible to efficiently cause the movement of charges generated on the surface of the adherend (protected body), and to exhibit excellent peeling antistatic properties. Furthermore, it is preferable to use the non-reactive ammonium salt type surfactant in combination because it can provide more excellent antistatic properties against peeling.

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

  Moreover, it is preferable that the HLB (Hydrophile-Lipophile-Blance) value of the said polysiloxane is 4-12, More preferably, it is 5-11, Most preferably, it is 6-10. When the HLB value is within the above range, not only peeling antistatic property can be imparted, but also the contamination property to the adherend becomes good, which is a preferred embodiment.

  Moreover, as a number average molecular weight of the said polysiloxane, it is preferable that it is 500-100000, More preferably, it is 1000-50000. When it is within the above range, the contamination of the adherend becomes good, which is a preferred mode. The number average molecular weight can be measured by GPC by the same method as the measurement of the molecular weight of the solvent-soluble component of the acrylic emulsion polymer.

Specific examples of the polysiloxane include trade names “KF-352A” (HLB value 7), KF-615 (HLB value 10), KF-6012 (HLB value 7), KF-351A (HLB value 12). ), KF-353 (HLB value 10), KF-945 (HLB value 4), KF-6013 (HLB value 10), KF-889 (HLB value 4), KF-6004 (HLB value 9) (and above, Shinetsu) Chemical Industries, Ltd.), FZ-2105 (HLB value 11), FZ-2123 (HLB value 8), FZ-2164 (HLB value 8), FZ-7001 (HLB value 7), SH8400 (HLB value 8), SH8700 (HLB value 7), SF8410 (HLB value 6), SF8422 (above, manufactured by Toray Dow Corning),
Examples thereof include TSF-4440 (HLB value 6), TSF-4445 (HLB value 7) (manufactured by Momentive Performance Materials). These compounds may be used alone or in combination of two or more.

(式中、Ｒ_１は１価の有機基、Ｒ_２，Ｒ_３及びＲ_４はアルキレン基、もしくはＲ_５はヒドロキシル基もしくは有機基、ｍ及びｎは０〜１０００の整数。但し、ｍ,ｎが同時に０となることはない。ａ及びｂは０〜１００の整数。但し、ａ,ｂが同時に０となることはない。) Among the alkylene oxide group-containing polysiloxanes, in particular, an alkylene oxide group-containing polysiloxane represented by the following formula is a preferable embodiment because it is easier to express peeling antistatic properties.

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

  In the polysiloxane, the end of the polyoxyalkylene side chain is more preferably a hydroxyl group. Use of the polysiloxane is effective because it can exhibit antistatic properties against peeling to the adherend (protected body).

As the polysiloxane, specifically, R _{1 in} the formula is an alkyl group such as a methyl group, an ethyl group or a propyl group, an aryl group such as a phenyl group or a tolyl group, or an alkyl group such as a benzyl group or a phenethyl group. And a monovalent organic group exemplified by a group, each of which may have a substituent such as a hydroxyl group. R ₂ , R ₃ and R ₄ may be an alkylene group having 1 to 8 carbon atoms such as a methylene group, an ethylene group or a propylene group. Here, R ₃ and R ₄ are different alkylene groups, and R ₂ may be the same as or different from R ₃ or R ₄ . R ₃ and R ₄ are non-reactive quaternary ammonium salt surfactants having 2 or less methyl groups that can be dissolved in the polyoxyalkylene side chain, and other antistatic agents (for example, alkali metal salts). One of them is preferably an ethylene group or a propylene group. R ₅ may be an alkyl group such as a methyl group, an ethyl group or a propyl group, or a monovalent organic group exemplified by an acyl group such as an acetyl group or a propionyl group, each having a substituent such as a hydroxyl group. It may be. These compounds may be used alone or in combination of two or more. Moreover, you may have reactive substituents, such as a (meth) acryloyl group, an allyl group, and a hydroxyl group, in a molecule | numerator. Among the polysiloxanes having a polyoxyalkylene side chain, a polysiloxane having a polyoxyalkylene side chain having a hydroxyl group terminal is preferred because it is presumed that the compatibility is easily balanced.

[Water-dispersed acrylic pressure-sensitive adhesive composition]
The water-dispersed acrylic pressure-sensitive adhesive composition (pressure-sensitive adhesive composition) of the present invention may contain other various additives as necessary. Examples of various additives include pigments, fillers, leveling agents, dispersants, plasticizers, stabilizers, antioxidants, ultraviolet absorbers, ultraviolet stabilizers, anti-aging agents, antiseptics, antistatic agents (alkali metal Salt, etc.).

  In the pressure-sensitive adhesive composition of the present invention, the “water-dispersed type” means that it can be dispersed in an aqueous medium, that 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 pressure-sensitive adhesive composition of the present invention may be a dispersion using the aqueous medium or the like.

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

[Method for producing pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet)]
The pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) of the present invention is formed from the water-dispersed acrylic pressure-sensitive adhesive composition. The formation method of an adhesive layer is not specifically limited, The formation method of a well-known and usual adhesive layer can be used. The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition on a substrate or a release film (release liner) and then drying. When the pressure-sensitive adhesive layer is formed on a release (release) film, the pressure-sensitive adhesive layer can be bonded to a substrate and transferred to form.

  In forming the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet), the drying temperature is usually about 80 to 170 ° C., preferably 80 to 160 ° C., and a drying time of about 0.5 to 30 minutes, preferably 1 to 10 minutes. Further, the adhesive layer (adhesive sheet) is produced by aging at room temperature to 50 ° C. for 1 day to 4 weeks.

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

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

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

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

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

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

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

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

  The pressure-sensitive adhesive sheet of the present invention (the pressure-sensitive adhesive sheet with the base material) is, for example, applied to the surface of the base material on at least one side of the base material, and dried as necessary. Can be obtained by forming a pressure-sensitive adhesive layer on at least one side (direct copying method). Crosslinking is performed by dehydrating in the drying step, heating the pressure-sensitive adhesive sheet after drying, or the like. Moreover, after providing an adhesive layer once on a peeling film, an adhesive sheet can also be obtained by transferring an adhesive layer on a base material (transfer method). Although not particularly limited, the pressure-sensitive adhesive layer is preferably provided by a so-called direct copying method in which the pressure-sensitive adhesive composition is directly applied to the substrate surface. Since the pressure-sensitive adhesive layer of the present invention has a high solvent-insoluble content, the transfer method may not provide sufficient anchoring properties (adhesion) with the support.

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

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

  The surface of the substrate on the side where the pressure-sensitive adhesive layer is provided may be subjected to acid treatment, alkali treatment, primer treatment, corona treatment, plasma treatment, ultraviolet treatment, etc. for the purpose of improving the adhesion with the pressure-sensitive adhesive layer. It is preferable that an easy adhesion treatment is performed. Moreover, you may provide an intermediate | middle layer between a base material and an adhesive layer. The thickness of the intermediate layer is preferably, for example, 0.01-1 μm, more preferably 0.1-1 μm.

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

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

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

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

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

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

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

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

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

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

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

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

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

  In addition, the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive that can form a pressure-sensitive adhesive layer and a pressure-sensitive adhesive sheet excellent in peeling antistatic properties and pressure-sensitive adhesive properties (adhesiveness and removability). It is a composition, and can also be used for pressure-sensitive adhesive sheets, pressure-sensitive adhesive tapes, surface protective films and the like for re-peeling. For example, the adhesive sheet having the adhesive layer is re-peeled [for example, masking tape for building curing, masking tape for automobile coating, masking tape for electronic parts (lead frame, printed circuit board, etc.), masking tape for sandblast, etc. Masking tape, surface protection film for aluminum sash, surface protection film for optical plastic, surface protection film for optical glass, surface protection film for automobile protection, surface protection film for metal plate, back grind tape, Pelicle fixing tape, dicing tape, lead frame fixing tape, cleaning tape, dust removal tape, carrier tape, cover tape, and other semiconductor / electronic component manufacturing process adhesive tape, electronic equipment and electronic component packaging tape ,transport Tacking tapes of, bundling tapes, preferably used in the label such], and the like.

  In addition, the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) formed from the water-dispersed acrylic pressure-sensitive adhesive composition of the present invention is a polarizing plate constituting a panel such as a liquid crystal display, organic electroluminescence (organic EL), field emission display, It is preferably used as a surface protection application (surface protection film for optical members, etc.) of optical members (optical plastic, optical glass, optical film, etc.) such as retardation plates, antireflection plates, wavelength plates, optical compensation films, brightness enhancement films, 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.

  The optical member of the present invention is preferably formed by attaching the pressure-sensitive adhesive sheet. Since the pressure-sensitive adhesive sheet uses the water-dispersed acrylic pressure-sensitive adhesive composition, it is excellent in peeling antistatic property, re-peeling property, and adhesiveness (stickiness), so that it can be processed, transported, shipped, etc. This is useful for protecting the surface of the optical member (such as a polarizing plate). In particular, since it can be used for plastic products and the like that are likely to generate static electricity, it is very useful for preventing peeling electrification in the technical fields related to optical and electronic parts where charging is a particularly serious problem.

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

<Example 1>
(Preparation of acrylic emulsion polymer)
In a container, as shown in Table 1, 90 parts by weight of water and 96 parts by weight of 2-ethylhexyl acrylate (2EHA), 4 parts by weight of acrylic acid (AA), a reactive nonionic anionic emulsifier (Daiichi Kogyo Seiyaku ( Co., Ltd., trade name “AQUALON HS-1025”) 3 parts by weight was blended, and 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% by weight of the monomer emulsion. An amount was added and emulsion polymerization was performed at 65 ° C. for 1 hour with stirring. Thereafter, 0.05 parts 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. 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-dispersed acrylic pressure-sensitive adhesive composition)
In the aqueous dispersion of the acrylic emulsion polymer, an epoxy crosslinking agent [Mitsubishi Gas Chemical Co., Ltd., trade name, which is a water-insoluble crosslinking agent, per 100 parts by weight of the acrylic emulsion polymer (solid content) “TETRAD-C”, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, functional group number: 4] 2.5 parts by weight, non-reactive 4 having 2 or less methyl groups 1 part by weight of polyoxypropylene methyldiethylammonium chloride [trade name “ADEKA COAL CC-36” manufactured by ADEKA Co., Ltd.], which is a quaternary ammonium salt type surfactant, is used at 23 ° C., 300 rpm for 10 minutes using a stirrer. The mixture was stirred and mixed under stirring conditions to prepare a water-dispersed acrylic pressure-sensitive adhesive composition.

(Formation of adhesive layer, production of adhesive sheet)
Furthermore, an applicator manufactured by Tester Sangyo Co., Ltd. is applied on the corona-treated surface of a PET film (trade name “E7415”, thickness: 38 μm) manufactured by Toyobo Co., Ltd. And then applied (coating) so that the thickness after drying is 15 μm, then dried in a hot air circulating oven at 120 ° C. for 2 minutes, and then cured at room temperature for 1 week (aging), An adhesive sheet was obtained.

<Examples 2 to 10 and Comparative Examples 1 to 3>
As shown in Table 1, a monomer emulsion was prepared in the same manner as in Example 1 except that the raw material monomer and the blending amount were changed. In addition, about the additive which is not described in a table | surface, it prepared with the compounding quantity similar to Example 1. FIG. Further, using the monomer emulsion, a water-dispersed acrylic pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were obtained in the same manner as in Example 1.

[Evaluation]
The water-dispersed acrylic pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet obtained in the examples and comparative examples were evaluated by the following measurement method or evaluation method. Specific evaluation results are shown in Tables 1 and 2.

<23 ° C. × 25% RH peeling voltage (peeling speed: 10 m / min, vs. DU)>
The prepared pressure-sensitive adhesive sheet was cut into a size of 70 mm in width and 130 mm in length, the separator was peeled off, and then an acrylic plate (Mitsubishi Rayon Co., Ltd., acrylite, thickness: 1 mm, width: 70 mm, length) was previously removed. : 100 mm) was bonded to the surface of a polarizing plate (manufactured by Nitto Denko Corporation, trade name “SEG1425DU”) with a hand roller so that one end protruded 30 mm (vs. DU). Subsequently, after being left for one day in an environment of 23 ° C. × 25 ± 2% RH, a sample is set at a predetermined position as shown in FIG. One end protruding 30 mm was fixed to an automatic winder, and peeled so that the peeling angle was 150 ° and the peeling speed was 10 m / min (min). The potential of the polarizing plate surface generated at this time was measured with a potential measuring device (KSD-0103, manufactured by Kasuga Denki Co., Ltd.) fixed at a predetermined position. The stripping voltage at this time was “23 ° C. × 25% RH stripping voltage (peeling speed 10 m / min, vs. DU)”. The distance between the sample and the potential measuring device was 100 mm when measuring the acrylic plate surface. The measurement was performed in an environment of 23 ° C. × 25 ± 2% RH. The evaluation results are shown in Table 1.

<23 ° C. × 25% RH peeling voltage (peeling speed: 30 m / min, vs. DU)>
Also, instead of the “23 ° C. × 25% RH peeling band voltage (peeling speed: 10 m / min, vs. DU) peeling band voltage”, the peeling speed was 30 m / min, and the environment was 23 ° C. × 25 ± 2% RH. After leaving the sample for one day, the sample was set and the stripping voltage when the measurement was performed in an environment of 23 ° C. × 25 ± 2% RH was “23 ° C. × 25% RH stripping band voltage (peeling speed 30 m / min, vs. DU) ". The evaluation results are shown in Table 2.

<23 ° C. × 50% RH peeling voltage (peeling speed: 30 m / min, vs. DU)>
Also, instead of the “23 ° C. × 25% RH peeling band voltage (peeling speed: 10 m / min, vs. DU)”, the peeling speed was set to 30 m / min, and it was kept under the environment of 23 ° C. × 50 ± 2% RH. After standing for a day, a sample was set and the stripping voltage when the measurement was performed in an environment of 23 ° C. × 50 ± 2% RH was defined as “23 ° C. × 50% RH stripping band voltage (peeling speed 30 m / min, DU) ". The evaluation results are shown in Table 2.

  The release voltage (absolute value) of the pressure-sensitive adhesive sheet of the present invention is preferably 1.5 kV or less, more preferably 1.2 kV or less, particularly preferably 1.0 kV, regardless of the peeling speed. It is as follows. If the stripping voltage exceeds 1.5 kV, the liquid crystal alignment of the polarizing plate as the adherend is disturbed, which is not preferable.

<Initial peel strength against DU>
The prepared pressure-sensitive adhesive sheet is cut to a size of 25 mm in width and 100 mm in length, and the separator is peeled off. And a product name “SEG1425DU”, width: 70 mm, length: 100 mm) were laminated under the conditions of 0.25 MPa and 0.3 m / min to prepare an evaluation sample (vs. DU). After lamination, after leaving for 30 minutes in an environment of 23 ° C. × 50% RH, peeling (adhesion) force when peeled at a peeling speed of 30 m / min and a peeling angle of 180 ° with a universal tensile testing machine (N / 25 mm) Was measured and was defined as “the initial peel force against DU”. The measurement was performed in an environment of 23 ° C. × 50% RH. The evaluation results are shown in Table 1.

  In addition, as a DU initial peeling force with respect to DU of the adhesive sheet of this invention, 1.0 N / 25mm or less is preferable, It is more preferable that it is 0.1-1.0 N / 25mm, More preferably, it is 0.2-0. It is 8N / 25mm. It is preferable to set the peeling force to 1.0 N / 25 mm or less because the adhesive sheet can be easily peeled in the manufacturing process of the polarizing plate and the liquid crystal display device, and the productivity and handling properties are improved. Moreover, it is preferable by setting it as 0.1 N / 25mm or more because the float and peeling of an adhesive sheet are suppressed at a manufacturing process, and the protective function as an adhesive sheet for surface protection can fully be exhibited.

<Initial peel strength against AG>
Further, instead of the polarizing plate (manufactured by Nitto Denko Corporation, trade name “SEG1425DU”, width: 70 mm, length: 100 mm), the polarizing plate (manufactured by Nitto Denko Corporation, trade name “SEG1425DUAGS1”, width: 70 mm, length) : 100 mm) was used as “initial AG peel strength”. The evaluation results are shown in Table 1.

  In addition, as initial stage peeling force with respect to AG of the adhesive sheet of this invention, 1.0 N / 25mm or less is preferable, It is more preferable that it is 0.1-1.0 N / 25mm, More preferably, it is 0.2-0. It is 8N / 25mm. It is preferable to set the peeling force to 1.0 N / 25 mm or less because the adhesive sheet can be easily peeled in the manufacturing process of the polarizing plate and the liquid crystal display device, and the productivity and handling properties are improved. Moreover, it is preferable by setting it as 0.1 N / 25mm or more because the float and peeling of an adhesive sheet are suppressed at a manufacturing process, and the protective function as an adhesive sheet for surface protection can fully be exhibited.

<Peeling force ratio>
The peel strength ratio (vs. DU initial peel strength / AG initial peel strength) of the pressure-sensitive adhesive sheet of the present invention is preferably 1.7 or less, and more preferably 1.5 or less. If it is out of the range, it may be necessary to use a pressure-sensitive adhesive sheet for each adherend, which is not preferable. The evaluation results are shown in Table 1.

<PO mole content>
The content ratio (PO mole content) of propylene oxide groups contained in the alkylene oxide group (AO) -containing polysiloxane used in the present invention was determined by NMR measurement. In addition, NMR measurement was performed on the following measurement conditions using the nuclear magnetic resonance apparatus (the JEOL company make, EX-400).
Observation frequency: 400 MHz ( ¹ H), 100 MHz ( ¹³ C)
Measuring solvent: CDCl ₃
Measurement temperature: 23 ° C

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

2EHA: 2-ethylhexyl acrylate AA: acrylic acid MMA: methyl methacrylate HS-1025: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “AQUALON HS-1025” (reactive nonionic anionic emulsifier)
T / C: manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name “TETRAD-C” (1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, functional group number: 4) (insoluble) Crosslinker)
CC-36: manufactured by ADEKA Corporation, trade name “ADEKA COAL CC-36”, polyoxypropylene methyl diethylammonium chloride (methyl group: 1, (C ₂ H ₅ ) ₂ (CH ₃ ) N ⁺ (CH ₂ CH ( CH ₃ ) O) _n H · Cl ⁻ ) (non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups)
CC-42: manufactured by ADEKA Corporation, trade name “ADEKA COAL CC-42”, polyoxypropylene methyldiethylammonium chloride (methyl group: 1, (C ₂ H ₅ ) ₂ (CH ₃ ) N ⁺ (CH ₂ CH ( CH ₃ ) O) _n H · Cl ⁻ ) (non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups)
ES-L: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “Cathogen ES-L”, aliphatic alkyl quaternary ammonium salt (methyl group: 2, (R (CH ₃ ) ₂ (CH ₃ CH ₂ ) N) ) ⁺ · C ₂ H ₅ OSO ₃ ⁻ ) (non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups)
ES-O: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “Cathogen ES-O”, octyldimethylethylammonium ethyl sulfate (number of methyl groups: 2, (R (CH ₃ ) ₂ (CH ₃ CH ₂ ) N) ⁺ C ₂ H ₅ OSO ₃ ⁻ ) (non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups)
TML: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “Cathogen TML”, alkyltrimethylammonium chloride (methyl group number: 3, (RN (CH ₃ ) ₃ ) ⁺ · Cl ⁻ ), surfactant)
KF-353: manufactured by Shin-Etsu Silicone Co., Ltd., trade name “KF-353” (ethylene oxide-containing polysiloxane, HLB value: 10, PO molar content 0.1% or less)
KF-352A: Shin-Etsu Silicone Co., Ltd., trade name “KF-352A” (ethylene oxide-containing polysiloxane, HLB value: 7, PO molar content 49%)

  From the evaluation results in Tables 1 and 2, it can be confirmed that in all Examples, a pressure-sensitive adhesive sheet excellent in peeling antistatic properties and pressure-sensitive adhesive properties can be obtained and used for surface protection applications such as optical members. It was confirmed that it was suitable. In particular, as an adhesive property, the peel force ratio (vs. DU initial peel force / vs. AG initial peel force) is 1.7 or less. There is no need to use each adherend separately, and an adhesive sheet excellent in convenience is obtained.

  On the other hand, in Comparative Example 1, since a specific non-reactive ammonium salt type surfactant was not used, peeling antistatic property was inferior, and the peeling force ratio was out of the desired range. In Comparative Example 2 as well, a specific non-reactive ammonium salt type surfactant was not used, and a surfactant having more than two methyl groups was used, resulting in poor peel antistatic properties. In Comparative Example 3, when the acrylic emulsion polymer was prepared, the aggregation of the acrylic emulsion polymer was so severe that the pressure-sensitive adhesive sheet could not be produced.

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

Claims (10)

An acrylic emulsion polymer containing 0.5 to 10% by weight of at least (meth) acrylic acid alkyl ester (A) and carboxyl group-containing unsaturated monomer (B) as a raw material monomer;
A water-dispersible acrylic pressure-sensitive adhesive composition comprising: a non-reactive quaternary ammonium salt type surfactant having 2 or less methyl groups. The surfactant is composed of an anion and a cation,
The water-dispersed acrylic pressure-sensitive adhesive composition according to claim 1, wherein the anion and / or the cation contains an alkylene oxide group.   The water-dispersed acrylic pressure-sensitive adhesive composition according to claim 1 or 2, wherein the (meth) acrylic acid alkyl ester (A) has an alkyl group having 2 to 14 carbon atoms.   The water-dispersed acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 3, further comprising an alkylene oxide group-containing polysiloxane.   The HLB value of the said polysiloxane is 4-12, The water-dispersed acrylic adhesive composition in any one of Claims 1-4 characterized by the above-mentioned.   The water-dispersed acrylic pressure-sensitive adhesive composition according to claim 1, wherein the polysiloxane is composed of at least an ethylene oxide (EO) group. The polysiloxane comprises propylene oxide (PO) groups;
The water-dispersed acrylic adhesive according to any one of claims 1 to 6, wherein a molar content of the PO is 50% or less with respect to a total molar content of the EO and PO of 100%. Agent composition.   A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed from the water-dispersed acrylic pressure-sensitive adhesive composition according to claim 1 on at least one side of a substrate.   9. The peeling force (peeling speed 30 m / min) when the pressure-sensitive adhesive layer is stuck to a polarizing plate (manufactured by Nitto Denko Corporation, trade name: SEG1425DU) is 1 N / 25 mm or less. The adhesive sheet as described. An optical member formed by attaching the pressure-sensitive adhesive sheet according to claim 8 or 9.

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