JP6599618B2 - Adhesive sheet and optical member - Google Patents

Description

  The present invention relates to an adhesive sheet and an optical member. Specifically, the present invention is provided on a base material having a first surface and a second surface, an antistatic layer provided on the first surface of the base material, and the second surface of the base material. More specifically, the present invention relates to a pressure-sensitive adhesive sheet having an antistatic function. The pressure-sensitive adhesive sheet according to the present invention is suitable for applications that are affixed to plastic products and the like that are likely to generate static electricity. In particular, as a surface protective film used for the purpose of protecting the surface of an optical member (for example, a polarizing plate, a wave plate, a phase difference plate, an optical compensation film, a reflection sheet, a brightness enhancement film used in a liquid crystal display). Useful.

  Generally, an adhesive sheet (also referred to as a surface protective sheet or a surface protective film) has a configuration in which an adhesive is provided on a film-like substrate (support). For the purpose of protecting the adherend (for example, a polarizing plate as an optical member) from scratches and dirt during processing and transportation, the pressure-sensitive adhesive sheet is bonded to the adherend via the pressure-sensitive adhesive. Used.

  In such a pressure-sensitive adhesive sheet, a water-dispersed pressure-sensitive adhesive composition has been used as a composition used for forming a pressure-sensitive adhesive layer from the viewpoint of work environment at the time of coating (Patent Document 1). To 3).

  Moreover, since the adhesive sheet (surface protective film) and the adherend (for example, a polarizing plate which is an optical member) to which the adhesive sheet is affixed are made of a plastic material, it has high electrical insulation, friction and Easily generates static electricity due to peeling. For this reason, static electricity is likely to be generated even when the adhesive sheet is peeled off from the polarizing plate, which is an optical member. If voltage is applied to the liquid crystal while this static electricity remains, the orientation of the liquid crystal molecules may be lost. There is a concern that the panel may be missing. Also, the presence of static electricity can be a factor that attracts dust and reduces workability. Under such circumstances, the antistatic treatment is applied to the pressure-sensitive adhesive sheet. For example, as the surface layer of the pressure-sensitive adhesive sheet, an antistatic function is imparted by forming an antistatic layer or applying an antistatic coating. (See Patent Documents 4 and 5).

JP 2001-131512 A JP 2003-27026 A Japanese Patent No. 3810490 JP 2004-223923 A JP 2008-255332 A

  However, when the antistatic layer is provided on the back side of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet adhered to the adherend is observed from the back side (for example, in a bright room where external light enters or under a fluorescent lamp in a bright room) ), The appearance of the pressure-sensitive adhesive sheet appears to be entirely or partially whitish, resulting in a problem that visibility of the adherend surface is lowered.

  In addition, some adhesive sheets may be whitened (absorbed white) when stored in a high humidity environment (humidified) while attached to the adherend, making it difficult to inspect the adherend. Some have problems such as a significant decrease in inspection accuracy.

  Further, in recent years, PEDOT (poly (3,4-ethylenedioxythiophene) / PSS (polystyrene sulfonate) (polythiophene type) type as a conductive polymer used for imparting an antistatic function to the surface layer of the pressure-sensitive adhesive sheet. However, when the water dispersion type is stored in a solution state, agglomerates are generated and a uniform antistatic layer cannot be formed, resulting in poor workability. In addition, when the antistatic layer is formed using the conductive polymer, the PSS (corresponding to the dopant) is desorbed from PEDOT with the passage of time, and the surface resistivity and the stripping voltage are reduced. In addition, there is a risk of problems such as an increase in surface resistivity (deterioration) due to oxidative degradation or light degradation, and an increase (degradation) in surface resistivity. And Jill, the adhesive sheet upon peeling from the adherend, static electricity is generated, fear of the problem arises.

  Further, such an adhesive sheet is required to exhibit sufficient adhesiveness (adhesiveness) while being attached to the adherend, and is peeled off from the adherend after achieving the intended purpose. Therefore, it is required to exhibit excellent pick-up properties and removability.

  Accordingly, an object of the present invention is to provide a pressure-sensitive adhesive sheet having excellent antistatic properties, surface resistivity stability over time, whitening resistance, pickup properties and removability.

  As a result of intensive studies to achieve the above object, the present inventors have found that an antistatic layer using a specific raw material on the first surface of the substrate and an adhesive using a specific raw material on the second surface of the substrate. By providing an agent layer, the pressure-sensitive adhesive sheet is excellent in antistatic property, surface resistivity stability over time, whitening resistance, pick-up property and removability, and can also suppress whitening (humidity absorption whitening) under humid storage. As a result, the present invention was completed.

  That is, the pressure-sensitive adhesive sheet of the present invention comprises a substrate having a first surface and a second surface, an antistatic layer provided on the first surface of the substrate, and a pressure-sensitive adhesive on the second surface of the substrate. An antistatic layer comprising a polyaniline sulfonic acid as a conductive polymer component, a polyester resin as a binder, and an isocyanate cross-linking agent as a cross-linking agent. The pressure-sensitive adhesive layer has at least 70 to 99.5% by mass of (meth) acrylic acid alkyl ester (A) and 0.5% of carboxyl group-containing unsaturated monomer (B) as monomer components. Water-dispersed acrylic pressure-sensitive adhesive containing an acrylic emulsion polymer polymerized using a reactive emulsifier containing 10% by mass and containing a radical polymerizable functional group in the molecule Characterized in that it is formed from Narubutsu.

  In the pressure-sensitive adhesive sheet of the present invention, the antistatic agent composition preferably contains a fatty acid amide as a lubricant.

  In the pressure-sensitive adhesive sheet of the present invention, the substrate preferably contains polyethylene terephthalate and / or polyethylene naphthalate.

  The pressure-sensitive adhesive sheet of the present invention preferably further includes a water-insoluble crosslinking agent having two or more functional groups capable of reacting with carboxyl groups in the molecule.

  In the pressure-sensitive adhesive sheet of the present invention, the acrylic emulsion polymer further contains, as a monomer component, at least one monomer (C) selected from the group consisting of methyl methacrylate, vinyl acetate and diethyl acrylamide. Is preferred.

  In the pressure-sensitive adhesive sheet of the present invention, the solvent-insoluble content of the acrylic emulsion polymer is preferably 70% by mass or more.

  In the pressure-sensitive adhesive sheet of the present invention, the solvent-insoluble content of the pressure-sensitive adhesive layer is preferably 90% by mass or more, and the elongation at break at 23 ° C. is preferably 130% or less.

  The pressure-sensitive adhesive sheet of the present invention can react with the carboxyl group of the water-insoluble crosslinking agent with respect to 1 mol of the carboxyl group of the carboxyl group-containing unsaturated monomer (B) in the water-dispersed acrylic pressure-sensitive adhesive composition. The number of moles of the functional group is preferably 0.4 to 1.3 moles.

  In the pressure-sensitive adhesive sheet of the present invention, the acrylic emulsion polymer preferably contains the monomer (C) in an amount of 0.5 to 10% by mass.

  It is preferable that the adhesive sheet of this invention is used for the surface protection use for optical members.

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

  The pressure-sensitive adhesive sheet of the present invention is provided with an antistatic layer using a specific raw material on the first surface of the base material and an adhesive layer using a specific raw material on the second surface of the base material. It is useful because it has excellent surface resistivity stability over time, whitening resistance, pick-up properties and removability, and can also suppress whitening (humidity whitening) under humid storage.

It is typical sectional drawing which shows one structural example of the adhesive sheet which concerns on this invention. It is a schematic sectional drawing which shows an example of the peeling method of an adhesive sheet. It is explanatory drawing which shows the measuring method of back surface peeling force.

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

<Overall structure of adhesive sheet (surface protective film)>
The pressure-sensitive adhesive sheet (surface protective film) disclosed herein is generally in a form called a pressure-sensitive adhesive tape, pressure-sensitive adhesive label, pressure-sensitive adhesive film, etc., and in particular, an optical component (for example, a liquid crystal display such as a polarizing plate or a wave plate) It is suitable as an adhesive sheet (surface protective film) that protects the surface of the optical component during processing or transportation of the optical component used as a panel component. The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet is typically formed continuously, but is not limited to such a form, for example, a pressure-sensitive adhesive formed in a regular or random pattern such as a spot or stripe. It may be an agent layer. Further, the pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or a single sheet.

  The typical structural example of the adhesive sheet disclosed here is typically shown in FIG. The pressure-sensitive adhesive sheet 1 includes a base material (for example, a polyester film) 12, an antistatic layer 11 provided on the first surface 12, and a second surface of the base material 12 (a surface opposite to the antistatic layer 11). ) And the pressure-sensitive adhesive layer 13 provided. The pressure-sensitive adhesive sheet 1 is used by sticking the pressure-sensitive adhesive layer 13 on an adherend (a surface to be protected, for example, the surface of an optical component such as a polarizing plate). The pressure-sensitive adhesive sheet 1 before use (that is, before sticking to an adherend) has a release liner in which the surface of the pressure-sensitive adhesive layer 13 (sticking surface to the adherend) is at least the pressure-sensitive adhesive layer 13 side. It may be in a protected form. Alternatively, the pressure-sensitive adhesive sheet 1 may be wound into a roll shape so that the pressure-sensitive adhesive layer 13 is in contact with the back surface of the substrate 12 (the surface of the antistatic layer 11) and the surface thereof is protected. .

  As shown in FIG. 1, the antistatic layer 11 is formed directly on the first surface of the substrate 12 (without any other layer), and the antistatic layer 11 is exposed on the back surface of the pressure-sensitive adhesive sheet 1 ( That is, the mode in which the antistatic layer 11 also serves as the topcoat layer) is a film with an antistatic layer in which the antistatic layer 11 is provided on the substrate 12 as compared with the configuration in which the antistatic layer is provided separately from the topcoat layer. (As a result, the pressure-sensitive adhesive sheet using the film) can reduce the number of layers constituting the pressure-sensitive adhesive sheet, which is advantageous from the viewpoint of improving productivity.

<Base material>
Although it does not specifically limit as a base material of the adhesive sheet of this invention, A resin film is preferable. Such a resin film is preferably formed by molding various resin materials into a film shape. As said resin material, what can comprise the resin film excellent in the characteristic of 1 or 2 or more among transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, etc. is preferable. For example, polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate; celluloses such as diacetylcellulose and triacetylcellulose; polycarbonates; acrylic polymers such as polymethylmethacrylate A transparent resin film composed of a resin material (preferably a component contained in an amount of more than 50% by mass) is preferable. Examples of other resin materials constituting the resin film include styrenes such as polystyrene and acrylonitrile-styrene copolymer; for example, polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, ethylene-propylene copolymer, and the like. Examples thereof include resin materials mainly composed of olefins; polyvinyl chlorides; nylon 6, nylon 6,6, polyamides such as aromatic polyamide, and the like. In addition, polyimides, polysulfones, polyether sulfones, polyether ether ketones, polyphenylene sulfides, polyvinyl alcohols, polyvinylidene chloride, polyvinyl butyrals, polyarylates, polyoxymethylenes, epoxies, etc. A resin material as a component can be mentioned. In addition, the resin material which comprises the said resin film can be used individually or in combination of 2 or more types.

  The resin film for the substrate is preferably one having transparency and little anisotropy in optical characteristics (such as retardation). Generally, the lower the anisotropy, the better. In particular, in the resin film used for the base material of the pressure-sensitive adhesive sheet for optical parts, it is meaningful to reduce the optical anisotropy of the resin film. The resin film may have a single layer structure or a structure in which a plurality of layers having different compositions are laminated. Usually, a resin film having a single layer structure is preferred.

  In the pressure-sensitive adhesive sheet of the present invention, the base material is a resin film (polyester resin film) in which a resin (polyester resin) containing polyester as a main component (preferably a component containing more than 50% by mass) is formed into a film shape. It is preferable that In particular, a resin film (PET film) in which the polyester is mainly PET and a resin film (PEN film) in which the polyester is mainly PEN are preferable.

  Various additives such as an antioxidant, an ultraviolet absorber, an antistatic component, a plasticizer, and a colorant (pigment, dye, etc.) may be blended in the resin material constituting the substrate as necessary. Good. For example, corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of a primer are applied to the first surface of the substrate (the back surface, ie, the surface on which the antistatic layer is provided). Or the usual surface treatment may be given. Such surface treatment is preferably, for example, a treatment for improving the adhesion between the back surface of the base material and the antistatic layer. Furthermore, a surface treatment in which a polar group such as a hydroxyl group is introduced on the back surface of the substrate is also preferable. In addition, in the pressure-sensitive adhesive sheet of the present invention, the second surface (front surface, ie, the surface on the side where the pressure-sensitive adhesive layer is formed) of the base material may be subjected to the same surface treatment as the back surface. Such surface treatment is preferably a treatment for improving the adhesion between the substrate (support) and the pressure-sensitive adhesive layer (the anchoring property of the pressure-sensitive adhesive layer).

  Moreover, the thickness of the said base material can be suitably selected in consideration of the use, purpose, usage pattern, etc. of the pressure-sensitive adhesive sheet. The thickness of the substrate is preferably 10 to 200 μm, more preferably 15 to 100 μm, and still more preferably 20 to 70 μm, in consideration of workability such as strength and handleability and cost.

<Antistatic layer (topcoat layer)>
The pressure-sensitive adhesive sheet of the present invention comprises a substrate having a first surface and a second surface, an antistatic layer provided on the first surface of the substrate, and a pressure-sensitive adhesive composition on the second surface of the substrate. A pressure-sensitive adhesive sheet comprising: a polyaniline sulfonic acid as a conductive polymer component; a polyester resin as a binder; and an isocyanate-based cross-linking agent as a cross-linking agent. It is formed from an inhibitor composition. When the pressure-sensitive adhesive sheet has an antistatic layer (topcoat layer), the antistatic property of the pressure-sensitive adhesive sheet and the stability over time of the surface resistivity are improved, which is a preferred embodiment.

<Conductive polymer>
The antistatic layer contains polyaniline sulfonic acid as a conductive polymer component. By using the conductive polymer, the antistatic property based on the antistatic layer and the stability over time of the surface resistivity can be satisfied. The polyaniline sulfonic acid is “water-soluble”, but can be fixed in the antistatic layer by using an isocyanate-based crosslinking agent described later, and water resistance can be improved. By using the water-soluble conductive polymer-containing aqueous solution, an antistatic layer having excellent surface resistivity over time can be obtained, which is a preferred embodiment. On the other hand, when the conductive polymer used in forming the antistatic layer is “water-dispersible”, aggregates are generated when the antistatic layer is formed using the water-dispersible conductive polymer-containing solution. This is not preferable because it tends to be easy and cannot be applied uniformly, and the surface resistivity with time tends to be extremely inferior.

  As for the usage-amount of the said conductive polymer, 10-200 mass parts is preferable with respect to 100 mass parts of binder contained in an antistatic layer, More preferably, it is 25-150 mass parts, More preferably, it is 40-120. Part by mass. If the amount of the conductive polymer used is too small, the antistatic effect may be reduced. If the amount of the conductive polymer used is too large, the adhesion of the antistatic layer to the substrate may be reduced, or the transparency may be reduced. There is a risk of lowering, which is not preferable.

The polyaniline sulfonic acid used as the conductive polymer component preferably has a polystyrene equivalent weight average molecular weight (Mw) of 5 × 10 ⁵ or less, more preferably 3 × 10 ⁵ or less. In addition, the weight average molecular weight of these conductive polymers is usually preferably 1 × 10 ³ or more, and more preferably 5 × 10 ³ or more.

As a method of forming the antistatic layer, a method of applying and drying (or curing) a coating material (antistatic agent composition) for forming an antistatic layer on the first surface of the base material (support) can be adopted. The conductive polymer component used for the preparation of the antistatic agent composition includes polyaniline sulfonic acid, a polyester resin as a binder, and an isocyanate crosslinking agent as a crosslinking agent as essential components. A dissolved form (conductive polymer aqueous solution or simply referred to as an aqueous solution) can be preferably used. Such an aqueous conductive polymer solution is prepared by, for example, dissolving a conductive polymer having a hydrophilic functional group (which can be synthesized by a method such as copolymerizing a monomer having a hydrophilic functional group in the molecule) in water. can do. Examples of the hydrophilic functional group include a sulfo group, amino group, amide group, imino group, hydroxyl group, mercapto group, hydrazino group, carboxyl group, quaternary ammonium group, sulfate group (—O—SO ₃ H), phosphorus An acid ester group (for example, —O—PO (OH) ₂ ) and the like are exemplified. Such hydrophilic functional groups may form a salt.

  Moreover, as a commercial item of the said polyaniline sulfonic acid aqueous solution, Mitsubishi Rayon Co., Ltd. brand name "aqua-PASS" etc. are illustrated.

  The antistatic layer disclosed herein contains polyaniline sulfonic acid (polyaniline type) as an essential component as the conductive polymer component. For example, one or more other antistatic components (conductive polymer) Organic conductive materials other than the above, inorganic conductive materials, antistatic agents, etc.) may be included together. In a preferred embodiment, the antistatic layer contains substantially no antistatic component other than the conductive polymer, that is, the antistatic component contained in the antistatic layer is substantially only a conductive polymer. The embodiment consisting of can be implemented more preferably.

  Examples of the organic conductive substance include cation type antistatic agents having a cationic functional group such as a quaternary ammonium salt, a pyridinium salt, a primary amino group, a secondary amino group, and a tertiary amino group; sulfonates and sulfates Anionic antistatic agents having an anionic functional group such as salts, phosphonates, phosphate esters; amphoteric ionic antistatic agents such as alkylbetaines and their derivatives, imidazolines and their derivatives, alanine and their derivatives; amino alcohols Nonionic antistatic agents such as glycerin and derivatives thereof, glycerin and derivatives thereof, polyethylene glycol and derivatives thereof; polymerization of monomers having the cation type, anion type or zwitterion type ion conductive groups (for example, quaternary ammonium base) Or an ion conductive polymer obtained by copolymerization; poly Include; thiophene, polyaniline, polypyrrole, polyethylene imine, a conductive polymer such as an allylamine polymer. Such an antistatic agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Examples of the inorganic 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, Examples thereof include copper iodide, ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), and the like. Such inorganic conductive materials may be used alone or in combination of two or more.

  Examples of the antistatic agent include a cationic antistatic agent, an anionic antistatic agent, an amphoteric ion antistatic agent, a nonionic antistatic agent, and a single ion having a cationic, anionic or zwitterionic ion conductive group. Examples thereof include an ion conductive polymer obtained by polymerizing or copolymerizing a monomer.

<Binder>
The antistatic layer contains a polyester resin as an essential component as a binder. The polyester resin is preferably a resin material containing polyester as a main component (typically exceeding 50% by mass, preferably 75% by mass or more, for example, 90% by mass or more). The polyester typically includes polyvalent carboxylic acids (typically dicarboxylic acids) having two or more carboxyl groups in one molecule and derivatives thereof (an anhydride, esterified product, halogenated product of the polyvalent carboxylic acid). Selected from one or more compounds (polyhydric carboxylic acid component) selected from, and polyhydric alcohols (typically diols) having two or more hydroxyl groups in one molecule. It is preferable to have a structure in which one or two or more compounds (polyhydric alcohol component) are condensed.

  Examples of compounds that can be employed as the polyvalent carboxylic acid component include oxalic acid, malonic acid, difluoromalonic acid, alkylmalonic acid, succinic acid, tetrafluorosuccinic acid, alkylsuccinic acid, (±) -malic acid, meso. -Tartaric acid, itaconic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, acetylenedicarboxylic acid, glutaric acid, hexafluoroglutaric acid, methylglutaric acid, glutaconic acid, adipic acid, dithioadipic acid, methyladipic acid, dimethyl Adipic acid, tetramethyladipic acid, methyleneadipic acid, muconic acid, galactaric acid, pimelic acid, suberic acid, perfluorosuberic acid, 3,3,6,6-tetramethylsuberic acid, azelaic acid, sebacic acid, perfluoro Sebacic acid, brassic acid, dodecyl dicar Aliphatic dicarboxylic acids such as acid, tridecyl dicarboxylic acid, tetradecyl dicarboxylic acid; cycloalkyl dicarboxylic acid (for example, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid), 1,4- (2- Alicyclic dicarboxylic acids such as norbornene) dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid (hymic acid), adamantane dicarboxylic acid, spiroheptane dicarboxylic acid; phthalic acid, isophthalic acid, dithioisophthalic acid, methylisophthalic acid, Dimethylisophthalic acid, chloroisophthalic acid, dichloroisophthalic acid, terephthalic acid, methylterephthalic acid, dimethylterephthalic acid, chloroterephthalic acid, bromoterephthalic acid, naphthalenedicarboxylic acid, oxofluorenedicarboxylic acid, anthracenedical Bonic acid, biphenyl dicarboxylic acid, biphenylene dicarboxylic acid, dimethyl biphenylene dicarboxylic acid, 4,4 "-p-terephenylene dicarboxylic acid, 4,4" -p-quarelphenyl dicarboxylic acid, bibenzyl dicarboxylic acid, azobenzene dicarboxylic acid, Homophthalic acid, phenylenediacetic acid, phenylenedipropionic acid, naphthalenedicarboxylic acid, naphthalenedipropionic acid, biphenyldiacetic acid, biphenyldipropionic acid, 3,3 ′-[4,4 ′-(methylenedi-p-biphenylene) dipropion Aromatic dicarboxylic acids such as acid, 4,4′-bibenzyldiacetic acid, 3,3 ′ (4,4′-bibenzyl) dipropionic acid, oxydi-p-phenylenediacetic acid; Acid anhydrides of any of the polyhydric carboxylic acids mentioned above (Eg alkyl esters). It can be a monoester, a diester or the like. ); Acid halides corresponding to any of the polyvalent carboxylic acids described above (for example, dicarboxylic acid chloride); and the like.

  Preferable examples of the compound that can be employed as the polyvalent carboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and acid anhydrides thereof; adipic acid, sebacic acid, azelaic acid, succinic acid, Aliphatic dicarboxylic acids such as fumaric acid, maleic acid, hymic acid, 1,4-cyclohexanedicarboxylic acid, and acid anhydrides thereof; and lower alkyl esters of the dicarboxylic acids (for example, monoalcohols having 1 to 3 carbon atoms) Ester) and the like.

  On the other hand, examples of compounds that can be employed as the polyhydric alcohol component include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and 1,4-butanediol. , Neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol, diethylene glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 2-methyl- Diols such as 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, xylylene glycol, hydrogenated bisphenol A, and bisphenol A Is mentioned. Other examples include alkylene oxide adducts (for example, ethylene oxide adducts, propylene oxide adducts, etc.) of these compounds.

The molecular weight of the polyester resin is, for example, about 5 × 10 ^{3 to} 1.5 × 10 ⁵ (preferably 1 × 10 5) as a weight average molecular weight (Mw) in terms of standard polystyrene measured by gel permeation chromatography (GPC). ^4-6 × 10 ⁴ ). Moreover, the glass transition temperature (Tg) of the said polyester resin can be 0-120 degreeC (preferably 10-80 degreeC), for example.

  As the polyester resin, a commercially available product name “Vylonal” manufactured by Toyobo Co., Ltd. can be used.

  The antistatic layer may be a resin other than a polyester resin (for example, an acrylic resin, an acrylic-retane resin, 1 type or 2 or more types of resins selected from acrylic styrene resin, acrylic silicone resin, silicone resin, polysilazane resin, polyurethane resin, fluororesin, polyolefin resin, and the like. A preferred embodiment of the technology disclosed herein is a case where the binder of the antistatic layer is substantially composed only of a polyester resin. For example, the antistatic layer whose ratio of the polyester resin to a binder is 98-100 mass% is preferable. The proportion of the binder in the entire antistatic layer can be, for example, 50 to 95% by mass, and usually 60 to 90% by mass is appropriate.

<Lubricant>
In the technique disclosed herein, the antistatic layer preferably uses a fatty acid amide as a lubricant. By using fatty acid amide as a lubricant, a further release treatment (for example, a treatment in which a known release treatment agent such as a silicone release agent or a long-chain alkyl release agent is applied and dried) is applied to the surface of the antistatic layer. Even in the case where the coating is not performed, an antistatic layer having both sufficient slipping property and printing adhesion can be obtained, so that it can be a preferable mode. Thus, the aspect in which the surface of the antistatic layer is not further peeled can prevent whitening due to the peeling treatment agent (for example, whitening due to storage under heating and humidification conditions). This is preferable. It is also advantageous from the viewpoint of solvent resistance.

  Specific examples of the fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, oleic acid amide, erucic acid amide, N-oleylparticic acid amide, N-stearyl stearic acid. Amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, methylol stearic acid amide, methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid Amides, ethylene bishydroxystearic acid amides, ethylene bisbehenic acid amides, hexamethylene bisstearic acid amides, hexamethylene bisbehenic acid amides, hexamethylene hydroxystearic acid amides N, N′-distearyl adipic acid amide, N, N′-distearyl sebacic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl Examples include adipic acid amide, N, N′-dioleyl sebacic acid amide, m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N, N′-stearyl isophthalic acid amide, and the like. These lubricants may be used alone or in combination of two or more.

  The ratio of the lubricant to the whole antistatic layer can be 1 to 50% by mass, and usually 5 to 40% by mass is appropriate. When there is too little content rate of a lubricant, it exists in the tendency for slipperiness to fall easily. If the content of the lubricant is too large, the print adhesion may be lowered.

  The technology disclosed herein can be implemented in a mode in which the antistatic layer contains other lubricant in addition to the fatty acid amide, as long as the application effect is not significantly impaired. Examples of such other lubricants include various waxes such as petroleum wax (paraffin wax, etc.), mineral wax (montan wax, etc.), higher fatty acid (cellotic acid, etc.), and neutral fat (palmitic acid triglyceride, etc.). It is done. Alternatively, in addition to the wax, a general silicone-based lubricant, a fluorine-based lubricant, and the like may be supplemented. The technology disclosed herein can be preferably implemented in an embodiment that does not substantially contain such a silicone-based lubricant, a fluorine-based lubricant and the like. In addition, when using many said silicone type lubricants, since it exists in the tendency to be inferior to pick-up property, it is unpreferable. However, as long as the application effect of the technology disclosed herein is not significantly impaired, the inclusion of a silicone compound used for a purpose other than the lubricant (for example, as an antifoaming agent contained in the antistatic agent composition described later) Is not to be excluded.

<Crosslinking agent>
The antistatic layer contains an isocyanate-based crosslinking agent as a crosslinking agent. By using the isocyanate-based crosslinking agent, the water-soluble polyaniline sulfonic acid, which is an essential component when forming the antistatic layer, can be fixed in the binder, has excellent water resistance, and further improves printing adhesion. The effect can be realized.

  In addition, as the isocyanate-based crosslinking agent, it is preferable to use a blocked isocyanate-based crosslinking agent that is stable even in an aqueous solution. Specific examples of the blocked isocyanate-based crosslinking agent include isocyanate-based crosslinking agents that can be used in the preparation of general pressure-sensitive adhesive layers and antistatic layers (for example, isocyanate compounds (isocyanates used in pressure-sensitive adhesive layers described later) Cross-linking agents)) with alcohols, phenols, thiophenols, amines, imides, oximes, lactams, active methylene compounds, mercaptans, imines, ureas, diaryl compounds, and bisulfite Those blocked with soda can be used.

  The antistatic layer in the technology disclosed herein includes an antistatic component, an antioxidant, a colorant (pigment, dye, etc.), a fluidity modifier (thixotropic agent, thickener, etc.), a film-forming as necessary. Additives such as auxiliaries, surfactants (antifoaming agents, etc.) and preservatives can be contained.

<Formation of antistatic layer>
The antistatic layer (topcoat layer) is a liquid composition (for forming an antistatic layer) in which essential components such as the conductive polymer component and additives used as necessary are dissolved in an appropriate solvent (such as water). Can be suitably formed by a technique including applying a coating material, an antistatic agent composition) to a substrate. For example, a method of applying the antistatic agent composition to the first surface of the substrate and drying it, and performing a curing treatment (heat treatment, ultraviolet treatment, etc.) as necessary can be preferably employed. The NV (nonvolatile content) of the antistatic composition can be, for example, 5% by mass or less (typically 0.05 to 5% by mass), and is usually 1% by mass or less (typically 0%). 10 to 1% by mass) is appropriate. In the case of forming an antistatic layer having a small thickness, the NV of the antistatic agent composition is preferably 0.05 to 0.50% by mass (for example, 0.10 to 0.40% by mass). Thus, by using a low NV antistatic agent composition, a more uniform antistatic layer can be formed.

  As the solvent constituting the antistatic agent composition for forming the antistatic layer, those capable of stably dissolving the antistatic layer forming components are preferable. Such a solvent may be an organic solvent, water, or a mixed solvent thereof. Examples of the organic solvent include esters such as ethyl acetate; ketones such as methyl ethyl ketone, acetone and cyclohexanone; cyclic ethers such as tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic such as n-hexane and cyclohexane. Hydrocarbons; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, and cyclohexanol; alkylene glycol monoalkyl ether (for example, ethylene glycol monomethyl ether) , Ethylene glycol monoethyl ether), glycol ethers such as dialkylene glycol monoalkyl ether; and the like can be used. In a preferred embodiment, the solvent of the antistatic agent composition is water or a mixed solvent containing water as a main component (for example, a mixed solvent of water and ethanol).

<Properties of antistatic layer>
The thickness of the antistatic layer in the technology disclosed herein is typically 3 to 500 nm, preferably 3 to 100 nm, more preferably 3 to 60 nm. If the thickness of the antistatic layer is too small, it becomes difficult to form the antistatic layer uniformly (for example, the thickness of the antistatic layer varies greatly depending on the location). Unevenness can easily occur. On the other hand, if it is too thick, the properties of the substrate (optical properties, dimensional stability, etc.) may be affected.

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, the surface resistivity (Ω / □) measured on the surface of the antistatic layer is preferably less than 1.0 × 10 ¹¹ , more preferably It is less than 8.0 × 10 ¹⁰ , more preferably less than 5.0 × 10 ¹⁰ . The pressure-sensitive adhesive sheet exhibiting a surface resistivity within the above range can be suitably used as a pressure-sensitive adhesive sheet used in the processing or transporting of articles that dislike static electricity such as liquid crystal cells and semiconductor devices. The surface resistivity can be calculated from the surface resistivity measured under an atmosphere of 23 ° C. and 50% RH using a commercially available insulation resistance measuring device.

  The pressure-sensitive adhesive sheet disclosed herein preferably has a property that the back surface (surface of the antistatic layer) can be easily printed with water-based ink or oil-based ink (for example, using an oil-based marking pen). In such a pressure-sensitive adhesive sheet, the identification number and the like of the adherend to be protected are described in the pressure-sensitive adhesive sheet in the process of processing or transporting the adherend (for example, an optical component) performed with the pressure-sensitive adhesive sheet attached. Suitable for display. Therefore, it is preferable that it is an adhesive sheet excellent in printability. For example, it is preferable that the solvent is alcohol-based and has high printability for oil-based inks containing pigments. Moreover, it is preferable that the printed ink is difficult to be removed by rubbing or transfer (that is, excellent in print adhesion). The pressure-sensitive adhesive sheet disclosed herein preferably has a solvent resistance that does not cause a noticeable change in appearance even if the print is wiped with alcohol (for example, ethyl alcohol) when the print is corrected or erased. .

  The pressure-sensitive adhesive sheet (surface protective film) disclosed herein can be implemented in an embodiment that further includes other layers in addition to the base material, the pressure-sensitive adhesive layer, and the antistatic layer. Examples of the arrangement of the “other layer” include a space between the first surface (back surface) of the substrate and the antistatic layer, a space between the second surface (front surface) of the substrate and the pressure-sensitive adhesive layer, and the like. The layer disposed between the back surface of the substrate and the antistatic layer can be, for example, a layer containing an antistatic component (the above-described antistatic layer). The layer disposed between the front surface of the substrate and the pressure-sensitive adhesive layer can be, for example, an undercoat layer (anchor layer) or an antistatic layer that enhances the anchoring property of the pressure-sensitive adhesive layer with respect to the second surface. An adhesive sheet having a configuration in which an antistatic layer is disposed on the front surface of the substrate, an anchor layer is disposed on the antistatic layer, and an adhesive layer is disposed thereon may be used.

<Adhesive layer>
The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the present invention is a water-dispersed acrylic pressure-sensitive adhesive composition (re-peeling water-dispersed acrylic pressure-sensitive adhesive composition) containing the following acrylic emulsion polymer as an essential component (“Book It may be referred to as “the pressure-sensitive adhesive composition of the invention”).

<Acrylic emulsion polymer>
The acrylic emulsion polymer in the pressure-sensitive adhesive composition of the present invention is composed of (meth) acrylic acid alkyl ester (A) and carboxyl group-containing unsaturated monomer (B) as essential monomer components (raw material monomers). It is a polymer (acrylic polymer). In addition, an 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” (any one or both of “acryl” and “methacryl”).

  Among them, the acrylic emulsion polymer is composed of methyl methacrylate, vinyl acetate, and diethylacrylamide in addition to the essential monomer components from the viewpoint of reducing appearance defects (such as dents) of the resulting pressure-sensitive adhesive layer. A polymer composed of at least one monomer (C) selected from the group as a monomer component is preferred. In addition, an acrylic emulsion type polymer can be used individually or in combination of 2 or more types. In the present specification, “at least one monomer (C) selected from the group consisting of methyl methacrylate, vinyl acetate and diethyl acrylamide” may be simply referred to as “monomer (C)”. . In the case where two or more types of monomers selected from the group consisting of methyl methacrylate, vinyl acetate and diethyl acrylamide are included in all the monomer components constituting the acrylic emulsion polymer, all of them are a single amount. Body (C).

  In the above pressure-sensitive adhesive sheet, if the pressure-sensitive adhesive layer has a defect in appearance (for example, the appearance characteristics such as the presence of dents on the surface and variations in the thickness of the pressure-sensitive adhesive layer are deteriorated), the appearance in the pressure-sensitive adhesive sheet When the appearance of the adherend is inspected with the characteristics deteriorated and the pressure-sensitive adhesive sheet attached, there is a risk that the inspection accuracy may be lowered. Note that a decrease in inspection accuracy may adversely affect productivity.

  The (meth) acrylic acid alkyl ester (A) is used as a main monomer component, and mainly has basic properties as a pressure-sensitive adhesive (or pressure-sensitive adhesive layer) such as adhesiveness (adhesiveness) and releasability (removability). It plays a role to express. 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 is a tendency to give hardness to the polymer to be formed and to exert an effect of adjusting the pickup property and removability of the pressure-sensitive adhesive layer. Although it does not specifically limit as said (meth) acrylic-acid alkylester (A), A C2-C16 (more preferably 2-10, more preferably 4-8) linear, branched or Examples include (meth) acrylic acid alkyl esters having a cyclic alkyl group. The (meth) acrylic acid alkyl ester (A) does not include methyl methacrylate.

  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, alkyl methacrylate having an alkyl group having 2 to 16 carbon atoms (more preferably 2 to 10) is preferable. Ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, methacryl 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 adhesiveness etc. The said (meth) acrylic-acid alkylester (A) 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 mass in the total amount (total amount) (total monomer component) (100 mass%) of the monomer component which comprises the said acrylic emulsion type polymer. 70 to 99% by mass, preferably 85 to 98% by mass, and more preferably 87 to 96% by mass. The content of 70% by mass or more is preferable because the adhesiveness (tackiness), pick-up property, and removability of the pressure-sensitive adhesive layer are improved. On the other hand, when the content exceeds 99.5% by mass, the content of the carboxyl group-containing unsaturated monomer (B) or the monomer (C) is decreased, thereby the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition. The appearance of the layer may deteriorate. 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 in the emulsion particle | grain surface which consists of said acrylic emulsion type polymer, 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. Further, by combining one or more water-insoluble crosslinking agents that react with carboxyl groups, it can also act as a crosslinking point in the pressure-sensitive adhesive layer forming stage by water removal. Furthermore, the adhesiveness (anchoring property) with a base material can also be improved through a water-insoluble crosslinking agent. Examples of such carboxyl group-containing unsaturated monomer (B) include (meth) acrylic acid (acrylic acid, methacrylic acid), itaconic acid, maleic acid, fumaric acid, crotonic acid, carboxyethyl acrylate, carboxypentyl. An acrylate etc. are 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. In addition, the said carboxyl group-containing unsaturated monomer (B) can be used individually or in combination of 2 or more types.

  Content of the said carboxyl group-containing unsaturated monomer (B) is 0.5-10 in the total amount (total amount) (total monomer component) (100 mass%) of the monomer component which comprises the said acrylic emulsion type polymer. It is mass%, Preferably it is 1-8 mass%, More preferably, it is 2-6 mass%. By controlling the content to 10% by mass or less, an increase in the peel force over time is suppressed by suppressing an increase in interaction with the functional group on the polarizing plate surface, which is an adherend, after the pressure-sensitive adhesive layer is formed. Can be suppressed, and peelability (removability) is improved, which is preferable. In addition, when the content exceeds 10% by mass, the carboxyl group-containing unsaturated monomer (B) (for example, acrylic acid) is generally water-soluble, so that it is polymerized in water to increase the viscosity (viscosity). Increase). On the other hand, the content of 0.5% by mass 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.

  The monomer (C) (methyl methacrylate, vinyl acetate, diethyl acrylamide) mainly plays a role of reducing appearance defects (such as dents) of the pressure-sensitive adhesive layer. These monomers (C) are polymerized with other monomers during the polymerization, and the polymer forms emulsion particles, thereby increasing the stability of the emulsion particles and reducing the gel (aggregates). . In addition, the affinity with the hydrophobic water-insoluble crosslinking agent is increased, the dispersibility of the emulsion particles is improved, and the dents due to poor dispersion are reduced.

  Although content of the said monomer (C) is not specifically limited, 0.5-10 in the total amount (total amount) (total monomer component) (100 mass%) of the monomer component which comprises the said acrylic emulsion type polymer. The mass% is preferable, more preferably 1 to 9 mass%, still more preferably 2 to 8 mass%. It is preferable for the content to be 0.5% by mass or more because the effect of blending the monomer (C) (the effect of suppressing poor appearance) can be sufficiently obtained. On the other hand, when the content is 10% by mass or less, the polymer forming the pressure-sensitive adhesive layer becomes relatively flexible, and the adhesion with the adherend is improved. In addition, in the case where two or more monomers selected from the group consisting of methyl methacrylate, vinyl acetate and diethyl acrylamide are contained in all monomer components constituting the acrylic emulsion polymer, methyl methacrylate The total content (total content) of vinyl acetate and diethyl acrylamide is the “content of monomer (C)”.

  As a monomer component constituting the acrylic emulsion polymer, for the purpose of imparting a specific function, the monomer component [(meth) acrylic acid alkyl ester (A), carboxyl group-containing unsaturated monomer (B), single monomer] Other monomer components other than the monomer (C)] may be used in combination. Examples of such a monomer component include, for example, an epoxy group-containing monomer such as glycidyl (meth) acrylate for the purpose of crosslinking in emulsion particles and improving cohesive force; polyfunctionality such as trimethylolpropane tri (meth) acrylate and divinylbenzene. You may add (use) a monomer in the ratio of less than 5 mass%, respectively. In addition, the said content is content in the total amount (all monomer components) (100 mass%) of the monomer component which comprises the said acrylic emulsion type polymer.

  As the other monomer component, the hydroxyl group-containing unsaturated monomer such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate is preferably less in content from the viewpoint of further reducing whitening contamination. Specifically, the addition amount of the hydroxyl group-containing unsaturated monomer (the total amount of monomer components constituting the acrylic emulsion polymer (total amount) (content in the total monomer components) (100% by mass)) is: It is preferably less than 1% by mass, more preferably less than 0.1% by mass, and still more preferably substantially free (for example, less than 0.05% by mass). However, when the purpose is to introduce cross-linking points such as cross-linking of hydroxyl group and isocyanate group or cross-linking of metal cross-linking, the content may be about 0.01 to 10% by mass.

  The acrylic emulsion polymer is obtained by emulsion polymerization of the monomer component (monomer mixture) with an emulsifier and a polymerization initiator.

<Reactive emulsifier>
The emulsifier used for emulsion polymerization of the acrylic emulsion polymer is a reactive emulsifier having a radical polymerizable functional group introduced into the molecule (a reactive emulsifier containing a radical polymerizable functional group). That is, the acrylic emulsion polymer is an acrylic emulsion polymer that is polymerized using a reactive emulsifier containing a radical polymerizable functional group in the molecule. The reactive emulsifier containing the radical polymerizable functional group may be 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 types or more can be selected and used. By using such a reactive emulsifier, the emulsifier is incorporated into the polymer, and contamination from the emulsifier is reduced. Moreover, by using a reactive emulsifier, whitening (humidity whitening) of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention under humidified storage is suppressed. For this reason, it is especially suitable for the surface protection use for optical members, such as an optical film.

  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. 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, when the water-insoluble crosslinking agent described later is a polyfunctional epoxy-based crosslinking agent having an epoxy group, the reactivity of the crosslinking agent can be improved by its catalytic action. When an anionic reactive emulsifier is not used, the crosslinking reaction is not completed by aging, and there may be a problem that the peeling force (adhesive strength) of the pressure-sensitive adhesive layer changes with time. In addition, 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.

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

In particular, since impurity ions may be a problem, it is desirable to remove the impurity ions and use a reactive emulsifier having an SO ₄ ^2- ion concentration of 100 μg / g or less. In the case of an anionic reactive emulsifier, it is desirable to use an ammonium salt reactive emulsifier. As a method for removing impurities from the reactive 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 amount of the reactive emulsifier is preferably 0.1 to 10 parts by mass, more preferably 100 parts by mass of the total amount (total amount) (total monomer components) of the monomer components constituting the acrylic emulsion polymer. 0.5 to 6 parts by mass, more preferably 1 to 4.5 parts by mass. A blending amount of 0.1 part by mass or more is preferable because stable emulsification can be maintained. On the other hand, by setting the blending amount to 10 parts by mass or less, the solvent-insoluble content of the pressure-sensitive adhesive layer after crosslinking can be easily controlled within the range specified in the present invention, and the cohesive strength of the pressure-sensitive adhesive (pressure-sensitive adhesive layer) is improved. It is preferable because contamination to the adherend can be suppressed and contamination by the emulsifier can be suppressed.

  The polymerization initiator used for the 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. In addition, the said polymerization initiator can be used individually or in combination of 2 or more types.

  The blending amount of the polymerization initiator can be appropriately determined according to the type of the initiator and the monomer component and is not particularly limited, but from the viewpoint of controlling the solvent-insoluble content of the pressure-sensitive adhesive layer within a preferable range. The total amount (total amount) of monomer components constituting the acrylic emulsion polymer is preferably from 0.01 to 1 part by weight, more preferably from 0.02 to 0.5 part by weight, based on 100 parts by weight of the total amount of monomer components (total monomer component). Part.

  For the emulsion polymerization of the acrylic emulsion polymer, any method such as general batch polymerization, continuous dropping polymerization, and divided dropping polymerization can be used, and the method is not particularly limited. From the standpoint of controlling the solvent-insoluble content and elongation at break of the pressure-sensitive adhesive layer after cross-linking within a preferred range, etc., batch polymerization and low temperature (for example, 55 ° C. or less, preferably 30 ° C. or less) It is desirable to polymerize. 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 70% by mass or more from the viewpoint of low contamination and appropriate peeling force (adhesive strength). Is preferable, more preferably 75% by mass or more, and still more preferably 80% by mass or more. When the solvent-insoluble content is less than 70% by mass, 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 strength becomes too high. The solvent-insoluble content can be controlled by the polymerization initiator, reaction temperature, type of emulsifier and monomer component, and the like. Although the upper limit of the said solvent insoluble part is not specifically limited, For example, it is 99 mass%.

  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”.

[Method for measuring solvent insolubles]
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 mass at the time is measured, and this mass is defined as the mass before immersion. The mass before immersion is the total mass of the acrylic emulsion polymer (collected above), the tetrafluoroethylene sheet, and the kite string. Further, the total mass of the tetrafluoroethylene sheet and the kite string is also measured, and this mass is defined as the wrapping mass.
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 the 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 mass is measured, and the mass is immersed. It is set as the rear mass. And a solvent insoluble content is computed from a following formula.
Solvent insoluble content (mass%) = (ab) / (c−b) × 100
(In the above formula, a is the mass after immersion, b is the wrapping mass, and c is the mass before immersion.)

  The weight average molecular weight (Mw) of the solvent-soluble component (sometimes referred to as “sol component”) of the acrylic emulsion polymer is not particularly limited, but is preferably 40,000 to 200,000, more preferably 50,000 to 150,000, more preferably 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 (tackiness) Will improve. Moreover, when 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 is improved.

  The weight-average molecular weight (Mw) of the solvent-soluble component of the acrylic emulsion polymer is the same as the treatment solution (ethyl acetate solution) after the ethyl acetate treatment obtained in the measurement of the solvent-insoluble component of the acrylic emulsion polymer described above. A sample (solvent soluble content of an acrylic emulsion polymer) obtained by air-drying underneath can be measured and determined by GPC (gel permeation chromatography). Specific methods for measuring include the following methods.

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

  The content of the acrylic emulsion polymer in the pressure-sensitive adhesive composition of the present invention is not particularly limited, but is preferably 80% by mass or more with respect to 100% by mass of the non-volatile content (solid content) of the pressure-sensitive adhesive composition, More preferably, it is 90-99 mass%.

<Water-insoluble crosslinking agent>
The pressure-sensitive adhesive composition of the present invention contains a water-insoluble crosslinking agent having two or more functional groups capable of reacting with a carboxyl group in the molecule (in one molecule) in addition to the acrylic emulsion polymer. Is preferred. The water-insoluble crosslinking agent is a water-insoluble compound, and is a 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). The number of functional groups capable of reacting with a carboxyl group in one molecule is preferably 3 to 5. As the number of functional groups capable of reacting with a carboxyl group in one molecule increases, the pressure-sensitive adhesive composition crosslinks more densely (that is, the cross-linked structure of the polymer forming the pressure-sensitive adhesive layer becomes dense). For this reason, it becomes possible to prevent the wetting and spreading of the pressure-sensitive adhesive layer after forming the pressure-sensitive adhesive layer. In addition, since the polymer that forms the adhesive layer is constrained, the functional groups (carboxyl groups) in the adhesive layer segregate on the adherend surface, and the peel force between the adhesive layer and the adherend increases with time. Can be prevented. 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 said water-insoluble crosslinking agent, For example, an epoxy group, an isocyanate group, a carbodiimide group etc. are mentioned. Among these, an epoxy group is preferable from the viewpoint of reactivity. Furthermore, since the reactivity is high, unreacted substances in the cross-linking reaction are less likely to remain, which is advantageous for low contamination. The unreacted carboxyl group in the pressure-sensitive adhesive layer increases the peel strength from the adherend over time. From the viewpoint that it can be prevented, a glycidylamino group is preferred. That is, as the water-insoluble crosslinking agent, 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 is an epoxy crosslinking agent (especially a glycidylamino crosslinking agent), the number of epoxy groups (particularly glycidylamino groups) in one molecule is 2 or more (for example, 2). ~ 6), and preferably 3-5.

  The term “water-insoluble” means that the solubility in 100 parts by mass of water at 25 ° C. (the mass of the compound (crosslinking agent) that can be dissolved in 100 parts by mass of water) is 5 parts by mass or less, preferably 3 It is 2 parts by mass or less, more preferably 2 parts by mass 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 force from increasing with time. Furthermore, since the water-insoluble cross-linking agent has high reactivity of the cross-linking reaction, the cross-linking reaction proceeds promptly by aging, and the peeling force from the adherend increases with time due to the unreacted carboxyl group in the pressure-sensitive adhesive layer. Can be prevented.

  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 mass of water (25 ° C.) and the cross-linking 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 non-volatile content in the aqueous phase (part by mass of non-volatile components relative to 100 parts by mass 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 mass or less with respect to 100 parts by mass 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 mass or less with respect to 100 parts by mass of water at 25 ° C.]; Tris (2,3-epoxypropyl) isocyclicate (for example, trade name “TEPIC-G” manufactured by Nissan Chemical Industries, Ltd.) And other epoxy-based crosslinking agents such as [solubility of 2 parts by mass or less with respect to 100 parts by mass of water at 25 ° C.]. In addition, a water-insoluble crosslinking agent can be used individually or in combination of 2 or more types.

  The blending amount of the water-insoluble crosslinking agent (content in the pressure-sensitive adhesive composition of the present invention) is the carboxyl group of the carboxyl group-containing unsaturated monomer (B) used as the monomer component of the acrylic emulsion polymer. The amount of the functional group capable of reacting with the carboxyl group of the water-insoluble crosslinking agent relative to 1 mol is preferably 0.4 to 1.3 mol. That is, with respect to “the total number of carboxyl groups of all carboxyl group-containing unsaturated monomers (B) used as the monomer component of the acrylic emulsion polymer”, “the carboxyl groups of all water-insoluble crosslinking agents and It is preferable that the ratio [functional group / carboxyl group capable of reacting with carboxyl group] (molar ratio) of “the total number of moles of reactive functional groups” is 0.4 to 1.3, more preferably 0.5 to 1.1, more preferably 0.5 to 1.0. By setting [functional group / carboxyl group capable of reacting with carboxyl group] to 0.4 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 force with time can be effectively prevented. Furthermore, since it becomes easy to control the solvent insoluble content and breaking elongation of the pressure-sensitive adhesive layer after crosslinking within the range defined by the present 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 is an epoxy crosslinking agent, the [epoxy group / carboxyl group] (molar ratio) is preferably 0.4 to 1.3, more preferably 0.5 to 1.1, more preferably 0.5 to 1.0. Furthermore, when the water-insoluble crosslinking agent is a glycidylamino crosslinking agent, it is preferable that [glycidylamino group / carboxyl group] (molar ratio) satisfy the above range.

For example, in the case where 4 g of a water-insoluble cross-linking agent having a functional group equivalent to a carboxyl group of 110 (g / eq) is added (blended) to the pressure-sensitive adhesive composition, the water-insoluble cross-linking agent is added. The number of moles of the functional group that can react with the carboxyl group possessed by 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 (addition 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-based crosslinking agent = [blending amount (addition amount) of epoxy-based crosslinking agent] / [epoxy equivalent] = 4/110

<Water-dispersed acrylic pressure-sensitive adhesive composition>
The 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. 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 above aqueous medium or the like.

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

  Examples of the non-reactive component include a component that bleeds to the surface of the pressure-sensitive adhesive layer such as a phosphate ester compound used in JP-A-2006-45412 and imparts peelability (removability). It is done. Non-reactive emulsifiers such as sodium lauryl sulfate and ammonium lauryl sulfate are also included.

  In particular, from the viewpoint of low contamination, it is preferable not to add a quaternary ammonium salt to the pressure-sensitive adhesive composition of the present invention, and it is preferable not to add a quaternary ammonium compound. These compounds are generally used as a catalyst for improving the reactivity of the epoxy crosslinking agent. However, these compounds are not incorporated into the polymer forming the pressure-sensitive adhesive layer, and can move freely in the pressure-sensitive adhesive layer, so that they easily deposit on the surface of the adherend, and these compounds are contained in the pressure-sensitive adhesive composition. In some cases, whitening contamination is likely to occur, and low contamination may not be achieved. Specifically, the content of the quaternary ammonium salt in the pressure-sensitive adhesive composition of the present invention is preferably less than 0.1% by mass, more preferably 100% by mass with respect to the pressure-sensitive adhesive composition (nonvolatile content). Is less than 0.01% by mass, more preferably less than 0.005% by mass. Furthermore, it is preferable that the content of the quaternary ammonium compound satisfies the above range.

  In addition, although a quaternary ammonium salt is not specifically limited, Specifically, it is a compound represented, for example by a following formula.

In the above formula, R ¹ , R ^m , R ⁿ , and R ^o represent an alkyl group, an aryl group, or a group derived therefrom (for example, an alkyl group or an aryl group having a substituent), excluding a hydrogen atom. . Z ⁻ represents a counter ion.

  The quaternary ammonium salt and the quaternary ammonium compound are not particularly limited, but for example, water such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, etc. Alkylammonium oxide and its salts, arylammonium hydroxide such as tetraphenylammonium hydroxide and its salts, trilaurylmethylammonium ion, didecyldimethylammonium ion, dicocoyldimethylammonium ion, distearyldimethylammonium ion, dioleyldimethylammonium ion Ion, cetyltrimethylammonium ion, stearyltrimethylammonium ion, behenyltrimethylammonium ion, cocoylbis (2-hydride) Xylethyl) methylammonium ion, polyoxyethylene (15) cocostearylmethylammonium ion, oleylbis (2-hydroxyethyl) methylammonium ion, cocobenzyldimethylammonium ion, laurylbis (2-hydroxyethyl) methylammonium ion, decylbis (2- And a base having hydroxyethyl) methylammonium ion as a cation and salts thereof.

  Further, the pressure-sensitive adhesive composition of the present invention is for improving the reactivity of the epoxy-based crosslinking agent in the same manner as the quaternary ammonium salt (or quaternary ammonium compound) from the viewpoint of low contamination. It is preferable not to add a tertiary amine and an imidazole compound which are generally used as a catalyst or the like. Therefore, it is preferable that the pressure-sensitive adhesive composition of the present invention does not substantially contain a tertiary amine and an imidazole compound. Specifically, the content of the tertiary amine and the imidazole compound (the total content of the tertiary amine and the imidazole compound) in the pressure-sensitive adhesive composition of the present invention is 100% of the pressure-sensitive adhesive composition (nonvolatile content). The content is preferably less than 0.1% by mass, more preferably less than 0.01% by mass, and still more preferably less than 0.005% by mass with respect to mass%.

  Examples of the tertiary amine include tertiary amine compounds such as triethylamine, benzyldimethylamine, and α-methylbenzyl-dimethylamine. Examples of the imidazole compound include 2-methylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 4-ethylimidazole, 4-dodecylimidazole, 2-phenyl-4-hydroxymethylimidazole, 2-ethyl-4- Examples thereof include hydroxymethylimidazole, 1-cyanoethyl-4-methylimidazole and 2-phenyl-4,5-dihydroxymethylimidazole.

  The pressure-sensitive adhesive composition of the present invention may contain various additives other than those described above as long as they do not affect the low contamination property. Examples of the various additives include pigments, fillers, leveling agents, dispersants, plasticizers, stabilizers, antioxidants, UV absorbers, UV stabilizers, antifoaming agents, anti-aging agents, and antiseptics. It is done.

  The pressure-sensitive adhesive composition of the present invention can be prepared by mixing the acrylic emulsion polymer and, if necessary, the water-insoluble crosslinking agent and other various additives. 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 to 50 degreeC is preferable, More preferably, it is 20 to 35 degreeC. The stirring time is preferably 5 minutes to 30 minutes, more preferably 10 minutes to 20 minutes. The stirring rotation speed is preferably 10 to 3000 rpm, more preferably 30 to 1000 rpm.

  In the pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) can be formed from the pressure-sensitive adhesive composition of the present invention. The formation method of the said adhesive layer is not specifically limited, The formation method of a well-known and usual adhesive layer can be used. For example, the pressure-sensitive adhesive composition of the present invention is applied (coated) on a substrate (transparent film substrate) or a release film (release liner), and dried and / or cured as necessary. A layer can be formed. As a specific method of drying and / or curing, for example, a method of heating and drying at a temperature condition of 70 to 160 ° C. for 10 seconds to 10 minutes can be mentioned. Crosslinking is performed by dehydrating in the drying step, heating the pressure-sensitive adhesive layer after drying, or the like.

  In addition, a known coating method can be used for coating (coating) in the method for forming the pressure-sensitive adhesive layer, and a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, or a dip coater can be used. A roll coater, bar coater, knife coater, spray coater, comma coater, direct coater or the like can be used.

  Although the thickness of the adhesive layer in the adhesive sheet of this invention is not specifically limited, 1-50 micrometers is preferable, More preferably, it is 1-35 micrometers, More preferably, it is 3-25 micrometers.

  The solvent-insoluble content of the pressure-sensitive adhesive layer (after crosslinking) in the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but is preferably 90% by mass or more, and more preferably 95% by mass or more. When the solvent-insoluble content is 90% by mass or more, transfer of contaminants to the adherend can be suppressed, and whitening contamination, pickup property and insufficient removability (heavy release) can be suppressed, which is preferable. Although the upper limit of the solvent insoluble part of the said adhesive layer is not specifically limited, For example, 99 mass% is preferable. In addition, the solvent insoluble content of the said adhesive layer (after bridge | crosslinking) 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 (after crosslinking)” in the above-mentioned “method for measuring solvent-insoluble matter”.

The elongation at break (elongation at break) at 23 ° C. of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet of the present invention is preferably 130% or less, more preferably 40 to 120%, still more preferably 60 to 115%. The elongation at break (elongation at break) is a measure of the degree of crosslinking of the pressure-sensitive adhesive layer, and if it is 130% or less, the crosslinked structure of the polymer forming the pressure-sensitive adhesive layer becomes dense. For this reason, it becomes possible to prevent the adhesive layer from spreading out. In addition, since the polymer that forms the adhesive layer is constrained, the functional groups (carboxyl groups) in the adhesive layer segregate on the adherend surface, and the peel force (adhesive force) from the adherend increases with time. Can be prevented.
The elongation at break (elongation at break) at 23 ° C. of the pressure-sensitive adhesive layer (after crosslinking) can be measured by a tensile test. Although not particularly limited, specifically, for example, the pressure-sensitive adhesive layer (after crosslinking) is rounded to prepare a cylindrical sample (length 50 mm, cross-sectional area (bottom area) 1 mm ² ), and using a tensile tester. Then, in an environment of 23 ° C. and 50% RH, a tensile test can be performed under conditions of an initial length (chuck interval) of 10 mm and a tensile speed of 50 mm / min, and the elongation at break can be measured.
More specifically, the pressure-sensitive adhesive layer (after crosslinking) used in the tensile test can be produced by the following method, for example.
The pressure-sensitive adhesive composition of the present invention is coated on an appropriate release film so that the thickness after drying is 50 μm, and then dried in a hot air circulation oven at 120 ° C. for 2 minutes, and further at 50 ° C. Curing (aging) is performed for 3 days to produce an adhesive layer. Although it does not specifically limit as said peeling film, For example, the PET film which surface-treated silicone can be used, for example, "MRF38" by Mitsubishi Resin Co., Ltd. is mentioned as a commercial item.

  The glass transition temperature (Tg) of the (meth) acrylic polymer (after crosslinking) forming the pressure-sensitive adhesive layer is not particularly limited, but is preferably -70 ° C to -10 ° C, more preferably -70 ° C to It is -20 degreeC, More preferably, it is -70 degreeC--40 degreeC, Most preferably, it is -70 degreeC--60 degreeC. A glass transition temperature of −10 ° C. or lower is preferable because sufficient peeling force (adhesive strength) can be obtained and floating and peeling during processing can be suppressed. Moreover, it is preferable that it is -70 degreeC, the malfunction that it will be heavy peeling in the higher-speed peeling speed (tensile speed) area | region and work efficiency falls can be suppressed. The glass transition temperature of the (meth) acrylic polymer (after crosslinking) forming the pressure-sensitive adhesive layer can be adjusted, for example, by the monomer composition when preparing the acrylic emulsion polymer.

  The pressure-sensitive adhesive sheet of the present invention has a release liner (separator) bonded to the pressure-sensitive adhesive surface for the purpose of protecting the pressure-sensitive adhesive surface (the surface of the pressure-sensitive adhesive layer that is attached to the adherend), if necessary. It may be in the form (form of a pressure-sensitive adhesive sheet with a release liner). Although it does not specifically limit as a base material which comprises a release liner, For example, paper, a synthetic resin film, etc. are mentioned. Among these, a synthetic resin film is preferable from the viewpoint of excellent surface smoothness. For example, the base material of the release liner is not particularly limited, but various resin films (particularly polyester films) are preferably exemplified. Although the thickness of a release liner is not specifically limited, It is preferable that it is 5-200 micrometers, More preferably, it is 10-100 micrometers. The surface of the release liner to be bonded to the pressure-sensitive adhesive layer is released using a conventionally known release agent (eg, silicone, fluorine, long chain alkyl, fatty acid amide, etc.) or silica powder. Or antifouling processing may be given.

  The pressure-sensitive adhesive sheet of the present invention may further contain other layers in addition to the base material, the antistatic layer and the pressure-sensitive adhesive layer. Examples of the arrangement of the “other layer” include a space between the first surface (back surface) of the substrate and the antistatic layer, a space between the second surface (front surface) of the substrate and the pressure-sensitive adhesive layer, and the like. The layer disposed between the back surface of the substrate and the antistatic layer may be, for example, a layer containing an antistatic component (another antistatic layer). The layer disposed between the front surface of the base material and the pressure-sensitive adhesive layer may be, for example, an undercoat layer (anchor layer) or an antistatic layer that enhances the anchoring property of the pressure-sensitive adhesive layer with respect to the second surface. An adhesive sheet having a configuration in which an antistatic layer is disposed on the front surface of the substrate, an anchor layer is disposed on the antistatic layer, and an adhesive layer is disposed thereon may be used.

  The pressure-sensitive adhesive sheet of the present invention is a polarizing plate, a retardation plate, an antireflection plate, a wavelength plate, an optical compensation film, and a brightness enhancement component for panels such as liquid crystal displays, organic electroluminescence (organic EL), field emission displays, and touch panel displays. 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 films and conductive films. 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 is preferably formed by bonding the pressure-sensitive adhesive sheet. That is, the optical member of the present invention preferably has a structure in which the pressure-sensitive adhesive sheet (surface protective film) is provided on the optical member. In addition, as an optical member, the above-mentioned optical member is mentioned preferably. Furthermore, in the optical member of the present invention, since the pressure-sensitive adhesive sheet is excellent in pick-up property and removability, the optical member is preferably not damaged when the pressure-sensitive adhesive sheet is peeled off.

  Hereinafter, several examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in the specific examples. In the following description, “part” and “%” are based on mass unless otherwise specified. In addition, the blending amount (addition amount) in the table indicates the non-volatile content (solid content).

  Each characteristic in the following description was measured or evaluated as follows.

<Measurement of solvent-insoluble content of acrylic emulsion polymer>
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 mass at the time is measured, and this mass is defined as the mass before immersion. The mass before immersion is the total mass of the acrylic emulsion polymer (collected above), the tetrafluoroethylene sheet, and the kite string. Further, the total mass of the tetrafluoroethylene sheet and the kite string is also measured, and this mass is defined as the wrapping mass.
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 the 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 mass is measured, and the mass is immersed. It is set as the rear mass. And a solvent insoluble content is computed from a following formula.
Solvent insoluble content (mass%) = (ab) / (c−b) × 100
(In the above formula, a is the mass after immersion, b is the wrapping mass, and c is the mass before immersion.)

<Measurement of weight average molecular weight (Mw) of solvent-soluble component of acrylic emulsion polymer>
The weight average molecular weight (Mw) was measured using a GPC apparatus (HLC-8220GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.

Sample concentration: 0.2% by mass (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column; TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1)
Detector: Differential refractometer (RI)
The weight average molecular weight was determined in terms of polystyrene.

<Solvent insoluble content of adhesive layer (after crosslinking)>
About 0.1 g of an adhesive layer (acrylic adhesive layer) was collected from the adhesive sheet and wrapped in a porous tetrafluoroethylene sheet (trade name “NTF1122”, manufactured by Nitto Denko Corporation) having an average pore diameter of 0.2 μm. Then, it tied up with the kite string, the mass in that case was measured, and this mass was made into mass before immersion. The mass before immersion is the total mass of the pressure-sensitive adhesive layer (collected above), the tetrafluoroethylene sheet, and the kite string. Further, the total mass of the tetrafluoroethylene sheet and the kite string was also measured, and this mass was taken as the wrapping mass.
Next, the pressure-sensitive adhesive layer wrapped with a tetrafluoroethylene sheet and tied with a kite string (referred to as “sample”) was placed in a 50 ml container filled with ethyl acetate and placed at 23 ° C. for 7 days. Then, the sample (after the 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 mass is measured, and the mass is immersed. It was set as the rear mass. And the solvent insoluble content was computed from the following formula.
Solvent insoluble content (% by mass) = (d−e) / (f−e) × 100
(In the above formula, d is the mass after immersion, e is the wrapping mass, and f is the mass before immersion.)

<Elongation at break of adhesive layer>
On the silicone-treated surface of a PET film (trade name “MRF38”, manufactured by Mitsubishi Plastics, Inc.) obtained by surface-treating the water-dispersed acrylic pressure-sensitive adhesive composition (solution) with silicone so that the thickness after drying is 50 μm. Then, it was dried at 120 ° C. for 2 minutes in a hot-air circulating oven and cured at 50 ° C. for 3 days to prepare a 50 μm thick adhesive layer (acrylic adhesive layer).

(Measurement of elongation at break)
Next, the pressure-sensitive adhesive layer was rolled to prepare a columnar sample (length 50 mm, cross-sectional area (bottom area) 1 mm ² ).
Measurement was performed using a tensile tester in an environment of 23 ° C. and 50% RH. Set the chuck so that the initial length of measurement (initial chuck interval) is 10 mm, perform a tensile test under the condition of a tensile speed of 50 mm / min, and measure the elongation at break [elongation at break (elongation at break)]. did.
The elongation at break (elongation at break) represents the elongation when the test piece (columnar sample of the pressure-sensitive adhesive layer) broke in the tensile test, and is calculated by the following formula.
“Elongation at break (Elongation at break)” (%) = (“Length of specimen at break (chuck interval at break)” − “Initial length (10 mm)”) ÷ “Initial length (10 mm)” × 100

<Thickness measurement>
Measurement was performed using a digital micrometer (manufactured by Anritsu, product name “KC-351C”).

<Measurement of surface resistivity>
Measurement was performed in accordance with JIS-K-6911 using a resistivity meter (manufactured by Mitsubishi Chemical Analytic, Hiresta UP MCP-HT450 type) in an atmosphere of temperature 23 ° C. and humidity 50% RH.
The surface resistivity (Ω / □) in the present invention is 1 week at the initial stage (23 ° C., 50% RH for 30 minutes) and at room temperature (23 ° C., 50% RH). The surface resistivity was measured for what was held.

The surface resistivity is preferably less than 1.0 × 10 ¹¹ Ω / □, more preferably less than 5.0 × 10 ¹⁰ Ω / □, both for the initial and room temperature holding for 1 week. More preferably, it is less than 1.5 × 10 ¹⁰ Ω / □. The pressure-sensitive adhesive sheet exhibiting a surface resistivity within the above range can be suitably used as a pressure-sensitive adhesive sheet used in the processing or transporting of articles that dislike static electricity such as liquid crystal cells and semiconductor devices.

<Whitening resistance evaluation>
The back of the adhesive sheet (the surface of the antistatic layer) was rubbed once by a gloved tester with a polyethylene terephthalate film with a thickness of 38 μm, and the rubbed part (scratched part) compared to the surroundings (non-scratched part). Whether or not it was transparent was visually observed. As a result, when the difference in transparency between the non-rubbed part and the scratched part could be visually confirmed, it was determined that whitening was observed. When whitening becomes remarkable, a phenomenon in which the contrast between the transparent rubbing portion and the surrounding area (whitening non-rubbing portion) becomes clearer is observed.
The visual observation was performed in a dark room (reflection method, transmission method) and a bright room as follows.
(A) Observation by a reflection method in a dark room: In a room (dark room) where outside light is blocked, a 100 W fluorescent lamp (Mitsubishi Electric) at a position of 100 cm from the back surface (surface of the antistatic layer) of each example. The product name “Lupica Line”) was placed, and the back of the sample was visually observed while changing the viewpoint.
(B) Observation by transmission method in a dark room: In the dark room, the fluorescent lamp is placed at a position 10 cm from the front surface of the pressure-sensitive adhesive sheet (the surface opposite to the side on which the antistatic layer is provided), and the viewpoint is determined. The back surface of the sample was visually observed while changing.
(C) Observation in a bright room: In a room (light room) having a window where external light enters, the back surface of the sample was visually observed on a sunny day and a window that was not exposed to direct sunlight.
The observation results under these three types of conditions are expressed in the following five stages.
0: No whitening (the rubbing portion and the non-rubbing portion were transparent) was not observed under any of the observation conditions.
1: Slight whitening was observed in the observation by the reflection method in a dark room.
2: Slight whitening was observed in the observation by the transmission method in a dark room.
3: Slight whitening was observed in observation in a bright room.
4: Clear whitening was observed in observation in a bright room.
The above-mentioned whitening resistance evaluation was carried out at the initial stage (after preparation, held for 3 days under conditions of 50 ° C. and 15% RH) and after heating and humidification (after preparation, under conditions of 50 ° C. and 15% RH for 3 days). The pressure-sensitive adhesive sheet was held for 2 weeks under high-temperature and high-humidity conditions of 60 ° C. and 95% RH.

<Measurement of back peel strength (adhesive strength)>
As shown in FIG. 2, the pressure-sensitive adhesive sheet 1 according to each example is cut into a size of 70 mm in width and 100 mm in length, and the pressure-sensitive adhesive surface (side on which the pressure-sensitive adhesive layer 20 is provided) 20 </ b> A of this pressure-sensitive adhesive sheet 1 is The tape 130 was used to fix it on the SUS304 stainless steel plate 132. A single-sided adhesive tape 160 (manufactured by Nitto Denko Corporation, trade name “No. 31B”, width 19 mm) 160 having an acrylic adhesive 162 on the resin layer film 164 was cut to a length of 100 mm. The pressure-sensitive adhesive surface 162A of the pressure-sensitive adhesive tape 160 was pressure-bonded to the back surface (that is, the surface of the antistatic layer 14) 1A of the pressure-sensitive adhesive sheet 1 at a pressure of 0.25 MPa and a speed of 0.3 m / min. This was left under conditions of 23 ° C. and 50% RH for 30 minutes. Thereafter, using a universal tensile testing machine, the adhesive tape 160 is peeled from the back surface 1A of the pressure-sensitive adhesive sheet 1 under the conditions of a peeling speed of 0.3 m / min and a peeling angle of 180 degrees, and the back peeling force [N / 19 mm at this time ] Was measured.

  The back surface peeling force is preferably 3.5 N / 19 mm or more, more preferably 4.0 N / 19 mm or more, still more preferably 5.0 N / 19 mm or more, and most preferably 6.0 N / 19 mm. It is 19 mm or more. If the peeling force is less than 3.0 N / 19 mm, a sufficient peeling force cannot be obtained, the pickup property is poor, and the peeling workability of the protective film is lowered, which is not preferable.

<Measurement of peeling force (adhesive strength) against polarizing plate>
A plain polarizing plate (TAC polarizing plate manufactured by Nitto Denko Corporation, SEG1425DU) having a width of 70 mm and a length of 100 mm was prepared as an adherend. The pressure-sensitive adhesive sheet according to each example was cut into a size of 25 mm in width and 100 mm in length, and the pressure-sensitive adhesive surface was pressure-bonded to the polarizing plate at a pressure of 0.25 MPa and a speed of 0.3 m / min. This was initially (held at 23 ° C. and 50% RH for 30 minutes) and after heating (held at 40 ° C. for 1 week) under an environment of 23 ° C. and 50% RH. The pressure-sensitive adhesive sheet was peeled from the polarizing plate using a universal tensile tester under the conditions of a peeling speed of 0.3 m / min and a peeling angle of 180 °, and the anti-polarizing plate peeling force [N / 25 mm] at this time was measured.

  The peeling force against the polarizing plate is preferably 0.05 to 2.5 N / 25 mm, more preferably 0.1 to 2.0 N / 25 mm, and still more preferably 0.2, both in the initial stage and after heating. It is -1.5N / 25mm, Most preferably, it is 0.3-1.2N / 25mm. When the peeling force is 2.5 N / 25 mm or less, for example, it is difficult to peel off the pressure-sensitive adhesive sheet in the manufacturing process of a polarizing plate or a liquid crystal display device, thereby suppressing the occurrence of problems that productivity and handleability are reduced. It is possible and preferable. Moreover, when it is 0.05 N / 25 mm or more, it becomes difficult for the pressure-sensitive adhesive sheet to float or peel off in the production process, and a good protective function as a pressure-sensitive adhesive sheet is easily obtained, which is preferable.

<Pickup property>
As shown in FIG. 3, the pressure-sensitive adhesive sheet 1 according to each example is cut into a size having a width of 50 mm and a length of 100 mm, and the pressure-sensitive adhesive surface (the side on which the pressure-sensitive adhesive layer 20 is provided) 20A of this pressure-sensitive adhesive sheet 1 is The sheet was pressure-bonded onto a plate (TAC polarizing plate manufactured by Nitto Denko Corporation, SEG1425DU) 50 at a pressure of 0.25 MPa and a speed of 0.3 m / min.
Single-sided adhesive tape 60 (manufactured by Nitto Denko Corporation, trade name “No. 31B”, width 19 mm) was cut into a width of 10 mm and a length of 50 mm. The pressure-sensitive adhesive layer (adhesive surface) 62 of the pressure-sensitive adhesive tape 60 was pressure-bonded by hand onto the center of the back surface of the pressure-sensitive adhesive sheet 1 having a width of 50 mm (that is, the surface of the antistatic layer 14) so that the end portion protruded 30 mm. This was left under conditions of 23 ° C. and 50% RH for 10 seconds. Then, the single-sided adhesive tape 60 was peeled by hand, and the peeling condition (pickup property) of the adhesive sheet 1 was evaluated.
The evaluation criteria were “good” when the pressure-sensitive adhesive sheet was peelable, and “poor” when the pressure-sensitive adhesive sheet could not be peeled off.

<Evaluation of printability (print adhesion)>
After printing on the surface of the antistatic layer using an X stamper manufactured by Shachihata Co., Ltd. in a measurement environment of 23 ° C. × 50% RH, a Nichiban cello tape (registered trademark) was applied on the printed surface. Next, peeling is performed under conditions of a peeling speed of 30 m / min and a peeling angle of 180 °. Then, the surface after peeling was visually observed, and x (printability failure) when 50% or more of the print area was peeled off, and ○ (good printability) when 50% or more of the print area remained without peeling. ).

<Preparation of antistatic agent composition solution 1>
Polyester resin Vylonal MD-1480 (25% aqueous solution, manufactured by Toyobo Co., Ltd.) as a binder, polyaniline sulfonic acid (aqua-PASS, weight average molecular weight 40,000, manufactured by Mitsubishi Rayon Co.) as a conductive polymer, and diisopropylamine as a crosslinking agent Blocked hexamethylene diisocyanate isocyanurate, as a lubricant, oleic acid amide in a mixed solvent of water / ethanol (1/3), binder in a solid content of 100 parts by mass, conductive polymer in a solid content of 75 parts by mass, 10 parts by mass of the cross-linking agent and 30 parts by mass of the lubricant were added, and the mixture was stirred and mixed well for about 20 minutes. Thus, an antistatic agent composition solution 1 having an NV of about 0.4% was prepared.

<Preparation of antistatic agent composition solution 3>
Polyester resin Vylonal MD-1480 (25% aqueous solution, manufactured by Toyobo Co., Ltd.) as the binder, poly (3,4-ethylenedioxythiophene) (PEDOT) 0.5% and polystyrene sulfonate (weight average molecular weight 150,000) as the conductive polymer (PSS) 0.8% aqueous solution (Bytron P, manufactured by HC Stark Co.) in a water / ethanol (1/1) mixed solvent, 100 parts by mass of binder in solid content, and conductive polymer 50 parts by mass of solid content and 5 parts by mass of melamine-based cross-linking agent (Sumimar M-50W, manufactured by Sumitomo Chemical Co., Ltd.) were added and mixed thoroughly by stirring for about 20 minutes. Thus, an antistatic agent composition solution 3 having an NV of about 0.4% was prepared.

<Preparation of antistatic agent composition solution 5>
In a water-alcohol solvent, an antistatic agent made of a cationic polymer (trade name “Bondip-P Main Agent” manufactured by Konishi Co., Ltd.) and an epoxy resin as a curing agent (Konishi Co., Ltd. product, trade name “Bonbon”). An antistatic composition solution 5 containing “dip-P curing agent”) at a mass ratio of 100: 46.7 on the basis of NV (about 0.8%) was prepared.

(Antistatic agent composition solutions 2 and 4)
Antistatic agent composition solutions 2 and 4 were prepared in the same manner as the antistatic agent composition solution 1 except that they were blended as shown in Table 1.

(Water-dispersed acrylic pressure-sensitive adhesive composition 1)
In a container, as shown in Table 2, 90 parts by weight of water and 94 parts by weight of 2-ethylhexyl acrylate (2EHA), 2 parts by weight of methyl methacrylate (MMA), 4 parts by weight of acrylic acid (AA), nonionic anion After adding 6 parts by mass of a system-reactive emulsifier (trade name “AQUALON HS-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 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 mass of water, 0.01 parts by mass of a polymerization initiator (ammonium persulfate), and 10 parts by mass of the monomer emulsion prepared above. %, And emulsion polymerization was carried out at 75 ° C. for 1 hour while stirring. Thereafter, 0.07 parts by mass of a polymerization initiator (ammonium persulfate) was further added, and then all of the remaining monomer emulsion (amount corresponding to 90% by mass) 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., 10% by mass of ammonia water was added to adjust the pH to 8, and an aqueous dispersion of acrylic emulsion polymer 1 was prepared.
Subsequently, as shown in Table 3, the aqueous dispersion of the acrylic emulsion polymer 1 obtained above was added to an epoxy-based crosslinking agent [Mitsubishi Gas Chemical Co., Ltd., trade name “Tetrad” as a water-insoluble crosslinking agent. -C ", 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent: 110, functional group number: 4] 3 parts by mass using a stirrer at 23 ° C., 300 rpm, 10 minutes The mixture was stirred and mixed under conditions to prepare a water-dispersed acrylic pressure-sensitive adhesive composition 1.

(Water-dispersed acrylic pressure-sensitive adhesive composition 2)
As shown in Table 2 and Table 3, the monomer raw material of the acrylic emulsion polymer is 92 parts by mass of 2-ethylhexyl acrylate (2EHA), 4 parts by mass of methyl methacrylate (MMA), 4 parts by mass of acrylic acid (AA). The water-dispersed acrylic pressure-sensitive adhesive was the same as the water-dispersed acrylic pressure-sensitive adhesive composition 1 except that the amount of the reactive emulsifier “AQUALON HS-10” was changed to 3 parts by mass. Composition 2 was prepared.

(Water-dispersed acrylic pressure-sensitive adhesive composition 3)
As shown in Table 2 and Table 3, the monomer raw material of the acrylic emulsion polymer is 88 parts by mass of 2-ethylhexyl acrylate (2EHA), 8 parts by mass of methyl methacrylate (MMA), 4 parts by mass of acrylic acid (AA). A water-dispersed acrylic pressure-sensitive adhesive composition 3 was prepared in the same manner as the water-dispersed acrylic pressure-sensitive adhesive composition 2 except that the water-dispersed acrylic pressure-sensitive adhesive composition 2 was changed.

(Water-dispersed acrylic pressure-sensitive adhesive composition 4)
As shown in Tables 2 and 3, the monomer raw material of the acrylic emulsion polymer was added to 92 parts by mass of 2-ethylhexyl acrylate (2EHA), 4 parts by mass of vinyl acetate (Vac), and 4 parts by mass of acrylic acid (AA). In the same manner as in the above water-dispersed acrylic pressure-sensitive adhesive composition 1 except that 4.5 parts by mass of “Adekaria soap SE-10N” was used as the reactive emulsifier instead of “AQUALON HS-10”. Thus, a water-dispersed acrylic pressure-sensitive adhesive composition 4 was prepared.

(Water-dispersed acrylic pressure-sensitive adhesive composition 5)
As shown in Tables 2 and 3, the monomer raw material of the acrylic emulsion polymer was added to 92 parts by mass of 2-ethylhexyl acrylate (2EHA), 4 parts by mass of diethylacrylamide (DEAA), and 4 parts by mass of acrylic acid (AA). As a reactive emulsifier, instead of “AQUALON HS-10”, 3 parts by weight of “ADEKA rear soap SE-10N” is used, and the amount of “TETRAD-C” which is a water-insoluble crosslinking agent is used. A water-dispersed acrylic pressure-sensitive adhesive composition 5 was prepared in the same manner as the water-dispersed acrylic pressure-sensitive adhesive composition 1 except that the amount was changed to 4 parts by mass.

(Water-dispersed acrylic pressure-sensitive adhesive composition 6)
As shown in Table 2 and Table 3, the water-dispersed acrylic pressure-sensitive adhesive composition described above, except that 3 parts by mass of “Tetrad-X” was used instead of “Tetrad-C” as the water-insoluble crosslinking agent. In the same manner as in No. 2, a water-dispersed acrylic pressure-sensitive adhesive composition 6 was prepared.

(Water-dispersed acrylic pressure-sensitive adhesive composition 7)
As shown in Table 2 and Table 3, the above water dispersion was used except that 4.5 parts by mass of “LA-16” which is a non-reactive emulsifier was used instead of “Aqualon HS-10” which was a reactive emulsifier. Water-dispersed acrylic pressure-sensitive adhesive composition 7 was prepared in the same manner as type acrylic pressure-sensitive adhesive composition 1.

(Water-dispersed acrylic pressure-sensitive adhesive composition 8)
As shown in Table 2 and Table 3, the monomer raw material of the acrylic emulsion polymer was changed to 99.6 parts by mass of 2-ethylhexyl acrylate (2EHA) and 0.4 parts by mass of acrylic acid (AA). A water-dispersed acrylic pressure-sensitive adhesive composition 8 was prepared in the same manner as the water-dispersed acrylic pressure-sensitive adhesive composition 2.

(Water-dispersed acrylic pressure-sensitive adhesive composition 9)
As shown in Table 2 and Table 3, the above water-dispersed acrylic is used except that the monomer raw material of the acrylic emulsion polymer is changed to 85 parts by mass of 2-ethylhexyl acrylate (2EHA) and 15 parts by mass of acrylic acid (AA). Preparation of water-dispersed acrylic pressure-sensitive adhesive composition 9 was attempted in the same manner as system pressure-sensitive adhesive composition 8, but aggregates were formed during the polymerization of the monomer components, and thus could not be used for the production of pressure-sensitive adhesive sheets. It was.

<Example 1>
(Formation of antistatic layer 1)
A transparent polyethylene terephthalate (PET) film having a thickness of 38 μm, a width of 30 cm, and a length of 40 cm, prepared by corona treatment on one surface (first surface) was prepared. The antistatic agent composition solution 1 was applied to the corona-treated surface of this PET film with a bar coater, and dried by heating to 130 ° C. for 2 minutes. Thus, the base material which has the transparent antistatic layer 1 of thickness 30nm on the 1st surface of PET film was produced.

(Preparation of adhesive sheet)
A release sheet having a release treatment with a silicone release treatment agent on one side of a PET film was prepared. The water-dispersed acrylic pressure-sensitive adhesive composition 1 was applied on the release surface (the surface subjected to the release treatment) of the release sheet and dried to form a pressure-sensitive adhesive layer having a thickness of 15 μm. After adhering the adhesive layer to the other surface of the substrate having the antistatic layer (second surface, ie, the surface where the antistatic layer is not provided), in an environment of 23 ° C. and 50% RH. It was cured (aged) for 7 days to obtain an adhesive sheet (surface protective film).

<Comparative Example 5>
<Preparation of antistatic layer 5>
A transparent polyethylene terephthalate (PET) film having a thickness of 38 μm, a width of 30 cm, and a length of 40 cm, prepared by corona treatment on one surface (first surface) was prepared. The antistatic agent composition solution 5 was applied to the corona-treated surface of this PET film so that the thickness after drying was 60 nm, and dried by heating at 130 ° C. for 1 minute to form an antistatic layer. Next, on the surface of the antistatic layer, as a slip agent, a long-chain alkyl carbamate-based release treatment agent (on the other hand, product manufactured by Yushi Kogyo Co., Ltd., trade name “Pyroyl 1010”) is based on NV (about 0.5%) The film was applied to a thickness of 40 nm, heated at 130 ° C. for 1 minute and dried to form an antistatic layer 5 having a two-layer structure.

  Tables 1 to 5 show the schematic configuration of the pressure-sensitive adhesive sheets according to Examples and Comparative Examples and the results of measuring or evaluating them by the above-described method. Moreover, when there is no special description, about Examples 2-6 and Comparative Examples 2-5, it is the method similar to Example 1, and based on Table 1-Table 3, antistatic agent composition solution, An antistatic layer, an acrylic emulsion polymer, a water-dispersed acrylic pressure-sensitive adhesive composition, and a pressure-sensitive adhesive sheet were prepared. Except for Comparative Example 5, the thickness of the antistatic layers of other Examples and Comparative Examples was all adjusted to 30 nm as in Example 1.

注）なお、アクリルエマルション系重合体においては、同じ構成（原料、配合量など）のアクリルエマルション系重合体を含んでいるが、便宜上、「アクリルエマルション系重合体１〜９」と記載した。また、アクリルエマルション系重合体９については、重合時に凝集物が生成した。

Note) The acrylic emulsion polymer contains the acrylic emulsion polymer having the same configuration (raw materials, blending amount, etc.), but for convenience, it is described as “acryl emulsion polymers 1 to 9”. Moreover, about the acrylic emulsion polymer 9, the aggregate produced | generated at the time of superposition | polymerization.

Abbreviations in Table 2 and Table 3 will be described below.
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate Vac: vinyl acetate DEAA: diethyl acrylamide AA: acrylic acid HS10: nonionic anionic reactive emulsifier (trade name “AQUALON HS-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
SE-10N: Nonionic anionic reactive emulsifier (trade name “ADEKA rear soap SE-10N”, manufactured by ADEKA Corporation)
LA-16: Anionic non-reactive emulsifier (trade name “Hytenol LA-16”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
T / C: Epoxy crosslinking agent which is a water-insoluble crosslinking agent [trade name “Tetrad-C”, manufactured by Mitsubishi Gas Chemical Co., Inc., 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, epoxy equivalent : 110, number of functional groups: 4]
T / X: Epoxy crosslinking agent which is a water-insoluble crosslinking agent [trade name “Tetrad-X”, manufactured by Mitsubishi Gas Chemical Company, Inc., 1,3-bis (N, N-diglycidylaminomethyl) benzene, epoxy equivalent : 100, number of functional groups: 4]

注)表４及び表５中の帯電防止層及び粘着剤層の種類(番号)とは、帯電防止剤組成物溶液及び水分散型アクリル系粘着剤組成物の種類(番号)と一致するものである。

Note) The types (numbers) of antistatic layers and pressure-sensitive adhesive layers in Tables 4 and 5 are the same as the types (numbers) of antistatic agent composition solutions and water-dispersed acrylic pressure-sensitive adhesive compositions. is there.

  From the above evaluation results, in all Examples, by using a pressure-sensitive adhesive sheet having a desired pressure-sensitive adhesive layer and antistatic layer, antistatic properties (surface resistivity, etc.), pressure-sensitive properties (removability, pickup) Etc.), whitening resistance, and print adhesion were confirmed. On the other hand, in the comparative example, since a pressure-sensitive adhesive sheet having a desired pressure-sensitive adhesive layer or antistatic layer was not used, a sheet satisfying all the characteristics could not be obtained.

1: Adhesive sheet 1A: Front surface (rear surface)
12: Base material 14: Antistatic layer 20: Adhesive layer 20A: Surface (adhesive surface)
50: Substrate (plain polarizing plate)
60: Single-sided adhesive tape (pickup tape)
62: Adhesive layer 64: Base material 130: Double-sided adhesive tape 132: Stainless steel plate 160: Adhesive tape 162: Adhesive 162A: Adhesive surface 164: Resin layer film

Claims (10)

A pressure-sensitive adhesive sheet comprising a base material having a first surface and a second surface, an antistatic layer provided on the first surface of the base material, and an adhesive layer on the second surface of the base material. And
The antistatic layer is formed from an antistatic agent composition containing polyaniline sulfonic acid as a conductive polymer component, a polyester resin as a binder, and an isocyanate-based crosslinking agent as a crosslinking agent,
The pressure-sensitive adhesive layer contains at least 70 to 99.5% by mass of (meth) acrylic acid alkyl ester (A) and 0.5 to 10% of carboxyl group-containing unsaturated monomer (B) as monomer components. It is formed from a water-dispersed acrylic pressure-sensitive adhesive composition containing an acrylic emulsion polymer that is polymerized using a reactive emulsifier containing a mass% and containing a radical polymerizable functional group in the molecule ,
The pressure-sensitive adhesive sheet, wherein the antistatic agent composition contains a fatty acid amide as a lubricant . The pressure-sensitive adhesive sheet according to claim 1, wherein the base material contains polyethylene terephthalate and / or polyethylene naphthalate. The pressure-sensitive adhesive according to claim 1 or 2 , wherein the water-dispersed acrylic pressure-sensitive adhesive composition further comprises a water-insoluble crosslinking agent having two or more functional groups capable of reacting with a carboxyl group in the molecule. Sheet. 2. The acrylic emulsion polymer further comprises at least one monomer (C) selected from the group consisting of methyl methacrylate, vinyl acetate and diethyl acrylamide as a monomer component. The pressure-sensitive adhesive sheet according to any one of to 3 . The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein a solvent-insoluble content of the acrylic emulsion polymer is 70% by mass or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5 , wherein the solvent-insoluble content of the pressure-sensitive adhesive layer is 90% by mass or more, and the elongation at break at 23 ° C is 130% or less. In the water-dispersed acrylic pressure-sensitive adhesive composition, the number of moles of the functional group capable of reacting with the carboxyl group of the water-insoluble crosslinking agent with respect to 1 mol of the carboxyl group of the carboxyl group-containing unsaturated monomer (B) is It is 0.4-1.3 mol, The adhesive sheet of any one of Claims 3-6 characterized by the above-mentioned. The pressure-sensitive adhesive sheet according to any one of claims 4 to 6 , wherein the acrylic emulsion-based polymer contains the monomer (C) in an amount of 0.5 to 10% by mass. It is used for the surface protection use for optical members, The adhesive sheet of any one of Claims 1-8 characterized by the above-mentioned. An optical member, characterized by comprising adhered the adhesive sheet according to any one of the claims 1-9.

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