JP2011202176A - Adhesive composition, adhesive sheets and surface protecting film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrification preventing an adhesive composition which is excellent in antistatic property of a non-electrification-prevented adherend upon peeling, and has reduced stainability in an adherend and is excellent in adhesion reliance, and electrification preventing adhesive sheets and a surface protecting film using the same.SOLUTION: The adhesive composition comprises a (meth)acryl-based polymer containing, as monomer components, 5-100 wt.% of a (meth)acrylic acid alkylene oxide adduct, 0-95 wt.% of a (meth)acryl-based monomer having a 1-14C alkyl group other than the adduct, and 0-95 wt.% of other polymerizable monomers, and an alkali metal salt.

Description

  The present invention relates to an acrylic pressure-sensitive adhesive composition. More specifically, the present invention relates to an antistatic pressure-sensitive adhesive composition, pressure-sensitive adhesive sheets and a surface protective film using the same.

  In particular, the pressure-sensitive adhesive sheets of the present invention are used in plastic products and the like that are likely to generate static electricity, and in particular, polarizing plates, wave plates, retardation plates, optical compensation films, reflection sheets, and brightness enhancements used in liquid crystal displays and the like. It is useful as a surface protective film used for the purpose of protecting the surface of an optical member such as a film.

  In recent years, when optical components and electronic components are transported and mounted on a printed circuit board, the individual components are often transported depending on a state of being wrapped with a predetermined sheet or affixed to an adhesive tape. Among these, surface protective films are particularly widely used in the field of optical and electronic components.

  The surface protective film is generally used for the purpose of preventing scratches and dirt generated during the processing and transportation of the protected body by bonding to the protected body via an adhesive layer applied to the protective film side. For example, in an optical member such as a polarizing plate or a wave plate used for a liquid crystal display panel, a surface protective film is bonded to the optical member via an adhesive layer. This surface protective film is peeled off and removed when it is no longer needed.

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

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

  In the past, as an attempt to suppress the electrostatic charge, a method of adding a low molecular surfactant to the adhesive and transferring the surfactant from the adhesive to the protected body to prevent the charge (for example, Patent Document 1) is disclosed. However, in such a method, the added low molecular surfactant easily bleeds to the surface of the pressure-sensitive adhesive, and when applied to a surface protective film, there is a concern about contamination of the object to be protected. Therefore, when the pressure-sensitive adhesive to which a low molecular surfactant is added is applied to the protective film for an optical member, there is a problem that particularly the optical properties of the optical member are impaired.

  Moreover, the adhesive sheet (for example, refer patent document 2) which made the adhesive layer contain the antistatic agent is disclosed. In such pressure-sensitive adhesive sheets, an antistatic agent comprising a polyether polyol compound and an alkali metal salt is added to the acrylic pressure-sensitive adhesive in order to suppress bleeding of the antistatic agent on the surface of the pressure-sensitive adhesive. However, even if such adhesive sheets are used, the bleed phenomenon such as an antistatic agent is unavoidable. As a result, when it is applied to a surface protective film, the bleed phenomenon is caused when treatment is performed over time or at a high temperature. Therefore, there is a problem that a phenomenon that the surface protective film partially floats from the object to be protected occurs.

  As described above, none of these problems can still be solved in a balanced manner, and in the technical field related to electronic equipment in which charging and contamination are particularly serious problems, an antistatic surface protective film has been developed. It is difficult to respond to further improvement requests.

JP-A-9-165460 JP-A-6-128539

  Therefore, the object of the present invention is to prevent the problem of the conventional antistatic pressure-sensitive adhesive sheets, and to prevent the charge to an uncharged adherend when it is peeled off. It is an object to provide an antistatic pressure-sensitive adhesive composition with reduced adhesion and excellent adhesion reliability, and an antistatic pressure-sensitive adhesive sheet and a surface protective film using the same.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by using the following pressure-sensitive adhesive composition, and have completed the present invention.

  That is, the pressure-sensitive adhesive composition of the present invention is 5 to 100% by weight of (meth) acrylic acid alkylene oxide adduct, and (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms other than those described above, 0 to 95%. %, And (meth) acrylic polymer having 0 to 95% by weight of other polymerizable monomers as monomer components, and an alkali metal salt, the (meth) acrylic The acid value of the polymer is 10 or less.

  The (meth) acrylic polymer in the present invention refers to an acrylic polymer and / or a methacrylic polymer, and (meth) acrylate refers to an acrylate and / or methacrylate.

  According to the pressure-sensitive adhesive composition of the present invention, as shown in the results of Examples, 5 to 100% by weight of (meth) acrylic acid alkylene oxide adduct is used as a monomer component, and the acid value is 10 or less (meth). Since an acrylic polymer is used as the base polymer and further contains an alkali metal salt, the pressure-sensitive adhesive layer that has been cross-linked with this reduces the contamination of the object to be protected (adhered body) and improves the antistatic properties when peeled off. It will be excellent. Although the details of the reason why the crosslinked product of the base polymer using the monomer component as a main component exhibits such properties are not clear, the alkali metal salt is coordinated to the ether group in the alkylene oxide adduct. This makes it difficult for the alkali metal salt to bleed, and it is presumed that excellent antistatic properties and low contamination properties are realized side by side.

  In the pressure-sensitive adhesive composition of the present invention, a (meth) acrylic polymer having an acid value of 10 or less is used. The acid value of the (meth) acrylic polymer in the present invention means the number of mg of potassium hydroxide required to neutralize free fatty acid, resin acid, etc. contained in 1 g of a sample. In the (meth) acrylic polymer skeleton, there are a large number of carboxyl groups and sulfonate groups that have a large interaction with the alkali metal salt, so that ionic conduction is hindered and excellent antistatic ability to the adherend is obtained. It is estimated that there was not. In the case of the (meth) acrylic polymer having an acid value of more than 10, an excellent antistatic ability for the adherend may not be obtained.

  In the present invention, an alkali metal salt is included. Adhesives that are compatible with (meth) acrylic polymers, etc. using alkali metal salts and have a well-balanced interaction, preventing static charge when peeled off, and reducing the contamination of protected objects A composition can be obtained.

  Examples of the alkali metal salt used in the above include metal salts composed of lithium, sodium, and potassium. Among them, lithium salts having particularly high dissociation properties are preferable.

  On the other hand, the pressure-sensitive adhesive layer of the present invention is obtained by crosslinking the pressure-sensitive adhesive composition described above. According to the pressure-sensitive adhesive layer of the present invention, since the pressure-sensitive adhesive composition exhibiting the above-described effects is cross-linked, the pressure-sensitive adhesive layer is excellent in antistatic properties when peeled off due to reduced contamination to the protector. It becomes. Therefore, it is particularly useful as an antistatic pressure-sensitive adhesive layer. In addition, pressure-sensitive adhesive sheets having more excellent heat resistance can be obtained by appropriately adjusting the structural unit, the structural ratio, the selection of the crosslinking agent, the addition ratio, and the like of the (meth) acrylic polymer.

  The pressure-sensitive adhesive sheets of the present invention are characterized in that a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition described above is formed on a support (support film). According to the pressure-sensitive adhesive sheets of the present invention, since the pressure-sensitive adhesive composition having the above-described effects is provided with a pressure-sensitive adhesive layer, it is possible to prevent static charge when it is peeled off and to reduce contamination on the protected object. Adhesive sheets. For this reason, it becomes very useful as an antistatic pressure-sensitive adhesive sheet in the technical field related to optical and electronic components in which contamination is a particularly serious problem.

  Furthermore, the surface protective film of the present invention is characterized in that a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition described above is formed on one side or both sides of a support. According to the surface protective film of the present invention, since the pressure-sensitive adhesive composition of the present invention having the above-described effects is used, it is possible to prevent the adherend that is not antistatic when peeled off, and to adhere to the adherend. Thus, the surface protection film is excellent in adhesion reliability. For this reason, it becomes very useful as an antistatic surface protective film in the technical field related to optical and electronic components in which contamination is a particularly serious problem.

Schematic configuration diagram of potential measurement unit used for measurement of peeling voltage in Examples etc.

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

  The pressure-sensitive adhesive composition of the present invention comprises (meth) acrylic acid alkylene oxide adduct 5 to 100% by weight, (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms other than the above, 0 to 95% by weight, And (meth) acrylic polymer containing 0 to 95% by weight of other polymerizable monomers as monomer components, and an alkali metal salt, the (meth) acrylic polymer The acid value is 10 or less.

  The (meth) acrylic polymer used in the present invention is not particularly limited as long as it is a (meth) acrylic polymer having adhesive properties corresponding to those described above.

  Examples of the oxyalkylene unit of the (meth) acrylic acid alkylene oxide adduct in the present invention include those having an alkylene group having 1 to 6 carbon atoms, such as oxymethylene group, oxyethylene group, oxypropylene group, oxybutylene. Group.

  Moreover, as addition number of moles of the oxyalkylene unit to (meth) acrylic acid, 1-30 are preferable from a compatible viewpoint with an alkali metal salt, and 1-20 are more preferable. The terminal of the oxyalkylene chain may be substituted with a hydroxyl group or other functional group, but is preferably substituted with an alkyl group, a phenyl group or the like in order to appropriately control the crosslinking density. .

  Specific examples of the (meth) acrylic acid alkylene oxide adduct in the present invention include, for example, methoxy-polyethylene glycol (meth) acrylate types such as methoxy-diethylene glycol (meth) acrylate and methoxy-triethylene glycol (meth) acrylate, ethoxy -Butoxy-polyethylene such as ethoxy-polyethylene glycol (meth) acrylate type such as diethylene glycol (meth) acrylate, ethoxy-triethylene glycol (meth) acrylate, butoxy-diethylene glycol (meth) acrylate, butoxy-triethylene glycol (meth) acrylate Glycol (meth) acrylate type, phenoxy-diethylene glycol (meth) acrylate, phenoxy-triethylene glycol Phenoxy such Lumpur (meth) acrylate - polyethylene glycol (meth) acrylate type, methoxy - methoxy dipropylene glycol (meth) acrylate - polypropylene glycol (meth) acrylate type and the like. Of these, ethoxy-diethylene glycol acrylate and the like are preferably used.

  The (meth) acrylic acid alkylene oxide adduct may be used alone or in admixture of two or more, but the total content is the monomer component of the (meth) acrylic polymer The content is preferably 5 to 100% by weight, more preferably 7 to 90% by weight, and particularly preferably 9 to 80% by weight. When the content of the (meth) acrylic acid alkylene oxide adduct is less than 5% by weight, the interaction with the alkali metal salt becomes insufficient, and the bleed suppression effect of the alkali metal salt and the contamination reduction effect of the protected object are sufficient. Since it cannot be obtained, it is not preferable.

  In the present invention, a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms can be used, but a (meth) acrylic monomer having an alkyl group having 2 to 13 carbon atoms is used. Is more preferable. For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate , 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate N-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, and the like. Of these, n-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferably used.

  In the present invention, the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms may be used alone or in combination of two or more, The content is preferably 0 to 95% by weight, more preferably 10 to 93% by weight, and particularly preferably 20 to 91% by weight in the monomer component of the (meth) acrylic polymer. By using a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, good interaction with an alkali metal salt and good adhesiveness can be appropriately adjusted.

  Other polymerizable monomers other than the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms include a polymerizable monomer for adjusting the glass transition point and peelability of the (meth) acrylic polymer. It can be used within a range not impairing the effects of the present invention.

  The other polymerizable monomer used in the (meth) acrylic polymer is particularly limited as long as it is a component other than an acrylate and / or methacrylate having a carboxyl group, a sulfonate group, a phosphate group, or an acid anhydride group-containing monomer. It can be used without doing. Among them, acrylates and / or methacrylates having a hydroxyl group are more preferably used because crosslinking can be easily controlled.

  The (meth) acrylic polymer used in the present invention is a (meth) acrylic polymer having an acid value of 10 or less, preferably 8 or less, and more preferably 6 or less.

  Specifically, for example, an acrylic polymer obtained by copolymerizing 2-ethylhexyl acrylate and acrylic acid can be cited as an acrylic polymer having a carboxyl group. In this case, the total amount of 2-ethylhexyl acrylate and acrylic acid Acrylic acid is 1.3 weight part or less with respect to 100 weight part.

  In the present invention, a (meth) acrylic monomer having a hydroxyl group can be used. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2- Examples thereof include hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and the like.

  In the case where the (meth) acrylic monomer having a hydroxyl group described above is included, the (meth) acrylic monomer having a hydroxyl group is 0.1 to 10 with respect to 100 parts by weight of all the structural units of the (meth) acrylic polymer. It is preferable that it is a weight part, and it is more preferable that it is 0.5-8 weight part.

  Other polymerizable monomers other than the above monomers used in the (meth) acrylic polymer include, for example, a cohesive force / heat resistance improving component such as a cyano group-containing monomer, a vinyl ester monomer, and an aromatic vinyl monomer, and an amide group. A component having a functional group that functions as an adhesive strength improvement or a crosslinking base point, such as a containing monomer, an imide group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, N-acryloylmorpholine, and a vinyl ether monomer can be appropriately used. These monomer compounds may be used alone or in admixture of two or more.

  Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

  Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl laurate, and the like.

  Examples of the aromatic vinyl compound include styrene, chlorostyrene, chloromethyl styrene, α-methyl styrene, other substituted styrenes, and the like.

  Examples of amide group-containing monomers include acrylamide, methacrylamide, diethyl acrylamide, N-vinyl pyrrolidone, N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide, N, N-diethyl acrylamide, N, N-diethyl methacryl. Examples include amide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, and diacetone acrylamide.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, (meth) acryloylmorpholine, and the like.

  Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

  Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.

  Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, and the like.

  In the present invention, other polymerizable monomers may be used alone or in combination of two or more, but the total content is a monomer of a (meth) acrylic polymer. The content is preferably 0 to 95% by weight, more preferably 10 to 93% by weight, and particularly preferably 20 to 91% by weight. By using other polymerizable monomers, good interaction with the alkali metal salt and good adhesiveness can be appropriately adjusted.

  The (meth) acrylic polymer used in the present invention has a weight average molecular weight of 100,000 to 5,000,000, preferably 200,000 to 4,000,000, and more preferably 300,000 to 3,000,000. When the weight average molecular weight is smaller than 100,000, the adhesive force tends to be generated due to a decrease in the cohesive force of the pressure-sensitive adhesive composition. On the other hand, when the weight average molecular weight exceeds 5,000,000, the fluidity of the polymer decreases and the wettability to the polarizing plate becomes insufficient, and the swelling generated between the polarizing plate and the pressure-sensitive adhesive composition layer of the pressure-sensitive adhesive sheet is reduced. There is a tendency to cause. A weight average molecular weight means what was obtained by measuring by GPC (gel permeation chromatography).

  In addition, the glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C. or lower (usually −100 ° C. or higher), preferably −10 ° C. or lower for the reason that it is easy to balance the adhesive performance. When the glass transition temperature is higher than 0 ° C., the polymer is difficult to flow and the wetting to the polarizing plate is insufficient, and there is a tendency to cause blisters generated between the polarizing plate and the pressure-sensitive adhesive composition layer of the pressure-sensitive adhesive sheet. is there. In addition, the glass transition temperature (Tg) of a (meth) acrylic-type polymer can be adjusted in the said range by changing the monomer component and composition ratio to be used suitably.

  The polymerization method of the (meth) acrylic polymer used in the present invention is not particularly limited, and it can be polymerized by a known method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization or the like. Further, the polymer obtained may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, and the like.

Examples of the alkali metal salt used in the present invention include a metal salt composed of lithium, sodium and potassium. Specifically, for example, a cation composed of Li ⁺ , Na ⁺ and K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (CF ₃ SO _{2) 3} C ^- is preferably used comprised a metal salt from the recognized anions. Among these, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ A lithium salt such as SO ₂ ) ₃ C is preferably used. These alkali metal salts may be used alone or in combination of two or more.

  About the compounding quantity of the alkali metal salt used in the said adhesive composition, it is preferable to mix | blend 0.01-5 weight part of alkali metal salt with respect to 100 weight part of (meth) acrylic-type polymers, 0.05 It is more preferable to add ~ 3 parts by weight. If the amount is less than 0.01 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if the amount is more than 5 parts by weight, the contamination of the protected object tends to increase.

  The pressure-sensitive adhesive composition of the present invention is more excellent in heat resistance by appropriately crosslinking a (meth) acrylic polymer. As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound, and the like are used. Among these, an isocyanate compound and an epoxy compound are particularly preferably used mainly from the viewpoint of obtaining an appropriate cohesive force. These compounds may be used alone or in combination of two or more.

  Examples of the isocyanate compound include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate, 2,4-tolylene diisocyanate, Aromatic isocyanates such as 4,4′-diphenylmethane diisocyanate and xylylene diisocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene Diisocyanate trimer adduct (trade name Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), isocyanurate of hexamethylene diisocyanate Body (trade name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) and isocyanate adducts and the like. These compounds may be used alone or in combination of two or more.

  Examples of the epoxy compound include N, N, N ′, N′-tetraglycidyl-m-xylenediamine (trade name: TETRAD-X, manufactured by Mitsubishi Gas Chemical Company) and 1,3-bis (N, N-diglycidyl). Aminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.). These compounds may be used alone or in combination of two or more.

  Examples of the melamine resin include hexamethylol melamine. Examples of the aziridine derivative include a commercial product name HDU (manufactured by Mutual Pharmaceutical Company), a product name TAZM (manufactured by Mutual Pharmaceutical Company), and a product name TAZO (manufactured by Mutual Pharmaceutical Company). These compounds may be used alone or in combination of two or more.

  Examples of the metal chelate compound include aluminum, iron, tin, titanium, and nickel as metal components, and acetylene, methyl acetoacetate, and ethyl lactate as chelate components. These compounds may be used alone or in combination of two or more.

  The content of the crosslinking agent used in the present invention is preferably 0.01 to 15 parts by weight, and 0.5 to 10 parts by weight, with respect to 100 parts by weight of the (meth) acrylic polymer. It is more preferable. When the content is less than 0.01 part by weight, the crosslinking formation by the crosslinking agent becomes insufficient, the cohesive force of the pressure-sensitive adhesive composition becomes small, and sufficient heat resistance may not be obtained, and the adhesive residue There is a tendency to cause. On the other hand, when the content exceeds 15 parts by weight, the cohesive force of the polymer is large, the fluidity is lowered, the wettability to the polarizing plate becomes insufficient, and it occurs between the polarizing plate and the pressure-sensitive adhesive composition layer. There is a tendency to cause dandruff. These crosslinking agents may be used alone or in combination of two or more.

  In the present invention, a polyfunctional monomer having two or more radiation-reactive unsaturated bonds can be added as a crosslinking agent. In such a case, the pressure-sensitive adhesive composition is crosslinked by irradiating with radiation or the like. As a polyfunctional monomer having two or more radiation-reactive unsaturated bonds in one molecule, for example, it can be crosslinked (cured) by irradiation with radiation such as vinyl group, acryloyl group, methacryloyl group, vinylbenzyl group. Examples thereof include polyfunctional monomers having two or more radiation reactivity of one kind or two or more kinds. As the polyfunctional monomer, generally, those having 10 or less radiation-reactive unsaturated bonds are preferably used. These compounds may be used alone or in combination of two or more.

  Specific examples of the polyfunctional monomer include, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 1,6 hexane. Examples thereof include diol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, and N, N′-methylenebisacrylamide.

  The amount of the polyfunctional monomer to be used is appropriately selected depending on the balance with the (meth) acrylic polymer to be crosslinked and further depending on the intended use of the pressure-sensitive adhesive sheets. In general, in order to obtain sufficient heat resistance by the cohesive force of the acrylic pressure-sensitive adhesive, it is preferably blended in an amount of 0.1 to 30 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. Moreover, it is more preferable to mix | blend at 10 weight part or less with respect to 100 weight part of (meth) acrylic-type polymers from the point of a softness | flexibility and adhesiveness.

  Examples of the radiation include ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, electron rays, and the like, and ultraviolet rays are preferably used from the viewpoints of controllability, good handleability, and cost. More preferably, ultraviolet rays having a wavelength of 200 to 400 nm are used. Ultraviolet rays can be irradiated using an appropriate light source such as a high-pressure mercury lamp, a microwave excitation lamp, or a chemical lamp. In addition, when using an ultraviolet-ray as a radiation, a photoinitiator is added to an acrylic adhesive.

  The photopolymerization initiator may be any substance that generates radicals or cations by irradiating ultraviolet rays having an appropriate wavelength that can trigger the polymerization reaction according to the type of the radiation-reactive component.

  Examples of radical photopolymerization initiators include benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, o-benzoylbenzoic acid methyl-p-benzoin ethyl ether, benzoin isopropyl ether, α-methylbenzoin, benzyldimethyl ketal, trichloro Acetophenones such as acetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-isopropyl-2-methylpropiophenone, etc. Propiophenones, benzophenone, methylbenzophenone, p-chlorobenzophenone, benzophenones such as p-dimethylaminobenzophenone, 2-chlorothioxanthone, 2- Thioxanthones such as tilthioxanthone and 2-isopropylthioxanthone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl) Examples include acylphosphine oxides such as-(ethoxy) -phenylphosphine oxide, benzyl, dibenzosuberone, and α-acyloxime ester. These compounds may be used alone or in combination of two or more.

  Examples of the cationic photopolymerization initiator include onium salts such as aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, organometallic complexes such as iron-allene complexes, titanocene complexes, and arylsilanol-aluminum complexes, nitro Examples thereof include benzyl ester, sulfonic acid derivative, phosphoric acid ester, phenol sulfonic acid ester, diazonaphthoquinone, and N-hydroxyimide sulfonate. These compounds may be used alone or in combination of two or more. The photopolymerization initiator is usually blended in an amount of 0.1 to 10 parts by weight and preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the acrylic polymer.

  It is also possible to use a photoinitiated polymerization aid such as amines in combination. Examples of the photoinitiator include 2-dimethylaminoethylbenzoate, dimethylaminoacetophenone, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamyl ester, and the like. These compounds may be used alone or in combination of two or more. It is preferable to mix | blend 0.05-10 weight part with respect to 100 weight part of (meth) acrylic-type polymers, and, as for a polymerization start adjuvant, it is more preferable to mix | blend in the range of 0.1-7 weight part.

  The pressure-sensitive adhesive composition of the present invention can appropriately contain an ether group-containing compound. By including the ether group-containing compound in the pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is further excellent in antistatic properties.

  The ether group-containing compound in the present invention is not particularly limited as long as it is a compound having an ether group, and a known ether group-containing compound is used.

  Specific examples of the ether group-containing compound include polyether polyol compounds and alkylene oxide group-containing compounds.

  Examples of the polyether polyol compound include polyethylene glycol (diol type), polypropylene glycol (diol type), polypropylene glycol (triol type), polytetramethylene ether glycol, and the above derivatives and polypropylene glycol-polyethylene glycol-polypropylene glycol blocks. Random copolymerization of polyethylene glycol and polypropylene glycol, such as copolymer, block copolymer of polypropylene glycol-polyethylene glycol, block copolymer of polyethylene glycol-polypropylene glycol-polyethylene glycol, random copolymer of polypropylene glycol-polyethylene glycol Examples thereof include a combination and a block copolymer.

  In addition, the end of the glycol chain may be a hydroxyl group, or may be substituted with an alkyl group, a phenyl group, or the like.

  As the alkylene oxide group-containing compound, for example, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene diamine, polyoxypropylene diamine, alkylene oxide group-containing (meth) acrylic polymer such as ethylene oxide group-containing acrylic polymer, Alkylene oxide group-containing polyether polymers such as ethylene oxide group-containing polyether polymers, alkylene oxide group-containing polyether esters such as ethylene oxide group-containing polyether esters, and alkylene oxide group-containing polyether esters such as ethylene oxide group-containing polyether ester amides Polyether amides containing alkylene oxide groups such as amides and polyether amide imides containing ethylene oxide groups Polyoxyalkylene alkyls such as imides, polyoxyethylene glycol fatty acid esters, polyoxyalkylene glycol fatty acid esters such as polyoxypropylene glycol fatty acid esters, polyoxysorbitan acid fatty acid esters, polyoxyethylene alkyl phenyl ethers, polyoxypropylene alkyl phenyl ethers Examples thereof include polyoxyalkylene alkyl ethers such as phenyl ether, polyoxyethylene alkyl ether and polyoxypropylene alkyl ether, and polyoxyalkylene alkyl allyl ethers such as polyoxyethylene alkyl allyl ether and polyoxypropylene alkyl allyl ether.

  Among them, polyether polyol compounds, alkylene glycol group-containing (meth) acrylic polymers, polyoxyethylene alkyl phenyl ether, polyoxypropylene alkyl phenyl ether, polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxy Ether type surfactants such as ethylene alkyl allyl ether and polyoxypropylene alkyl allyl ether are preferably used because they have a good balance of compatibility with the base polymer.

  As the alkylene glycol group-containing (meth) acrylic polymer, a (meth) acrylic polymer containing an alkylene glycol group-containing (meth) acrylate as an essential component can be used.

  Examples of the oxyalkylene unit to (meth) acrylate include those having an alkylene group having 1 to 6 carbon atoms, such as an oxymethylene group, an oxyethylene group, an oxypropylene group, and an oxybutylene group.

  Moreover, as addition mole number of the oxyalkylene unit to (meth) acrylate, 1-50 are preferable and 2-30 are more preferable.

  In addition, the terminal of the oxyalkylene chain may be substituted with a hydroxyl group, an alkyl group, a phenyl group, or the like.

  Examples of the alkylene glycol group-containing (meth) acrylate include methoxy-polyethylene glycol (meth) acrylate type such as methoxy-diethylene glycol (meth) acrylate and methoxy-triethylene glycol (meth) acrylate, ethoxy-diethylene glycol (meth) acrylate, Ethoxy-polyethylene glycol (meth) acrylate type such as ethoxy-triethylene glycol (meth) acrylate, butoxy-polyethylene glycol (meth) acrylate type such as butoxy-diethylene glycol (meth) acrylate, butoxy-triethylene glycol (meth) acrylate, Phenoxy-diethylene glycol (meth) acrylate, phenoxy-triethylene glycol (meth) acryl Phenoxy-polyethylene glycol (meth) acrylate type such as methoxy-polypropylene glycol (meth) acrylate type such as methoxy-dipropylene glycol (meth) acrylate, 2-ethylhexyl-polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (Meth) acrylate and the like.

  In addition to the above components, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (Meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl Using an acrylate and / or methacrylate having an alkyl group having 1 to 14 carbon atoms such as (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate and the like. It is also possible.

  Furthermore, phosphate group-containing (meth) acrylate, cyano group-containing (meth) acrylate, vinyl esters, aromatic vinyl compounds, acid anhydride group-containing (meth) acrylate, hydroxyl group-containing (meth) acrylate, amide group-containing (Meth) acrylate, amino group-containing (meth) acrylate, imide group-containing (meth) acrylate, epoxy group-containing (meth) acrylate, N-acryloylmorpholine, vinyl ethers and the like can also be used as appropriate.

  Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate.

  Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

  Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl laurate, and the like.

  Examples of the aromatic vinyl compound include styrene, chlorostyrene, chloromethyl styrene, α-methyl styrene, other substituted styrenes, and the like.

  Examples of the acid anhydride group-containing monomer include maleic anhydride, itaconic anhydride, and acid anhydride bodies of the above carboxyl group-containing monomers.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl Examples thereof include vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and the like.

  Examples of amide group-containing monomers include acrylamide, methacrylamide, diethyl acrylamide, N-vinyl pyrrolidone, N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide, N, N-diethyl acrylamide, N, N-diethyl methacryl. Examples include amide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, and diacetone acrylamide.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, (meth) acryloylmorpholine, and the like.

  Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

  Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.

  Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, and the like.

  The proportion of the alkylene glycol group-containing (meth) acrylate contained in the alkylene glycol group-containing (meth) acrylate polymer is preferably 10 to 70% by weight. If the proportion of the alkylene glycol group-containing (meth) acrylate is less than 10% by weight, sufficient charging characteristics cannot be obtained, while if it exceeds 70% by weight, it is in phase with the (meth) acrylic polymer as the base polymer. The solubility becomes poor and sufficient charging characteristics cannot be obtained.

  Moreover, said (meth) acrylate may be used independently and may be used in combination.

  Moreover, you may use an ether type surfactant as an ether group containing compound in this invention. Specific examples of ether type surfactants include, for example, ADEKA rear soap NE-10, ADEKA rear soap SE-10N, ADEKA rear soap SE-20N, ADEKA rear soap ER-10, ADEKA rear soap SR-10, and ADEKA rear. Examples include soap SR-20 (manufactured by Asahi Denka Co., Ltd.), Emulgen 120 (manufactured by Kao Corporation), Neugen EA130T (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the like.

  As the molecular weight of the ether group-containing compound (such as a polyether polyol compound or an ethylene oxide group-containing compound), those having a number average molecular weight of 10,000 or less are preferably used, and those having a molecular weight of 200 to 5000 are more preferably used. When the number average molecular weight exceeds 10,000, the contamination of the adherend tends to deteriorate. The number average molecular weight is obtained by measuring by GPC (gel permeation chromatography).

  The ether group-containing compounds (polyether polyol compounds, ethylene oxide group-containing compounds, etc.) may be used alone or in combination, but the blending amount is preferably 0.1% relative to 100 parts by weight of the base polymer. The amount is preferably 01 to 20 parts by weight, and more preferably 0.1 to 10 parts by weight. If the amount is less than 0.01 part by weight, sufficient charging characteristics cannot be obtained, and if it exceeds 20 parts by weight, bleeding to the adherend tends to increase and the adhesive strength tends to decrease, such being undesirable.

  Furthermore, the pressure-sensitive adhesive composition used for the pressure-sensitive adhesive sheets of the present invention may contain other known additives, for example, powders such as colorants and pigments, surfactants, plasticizers, pressure-sensitive adhesives, and the like. Property-imparting agent, low molecular weight polymer, surface lubricant, leveling agent, antioxidant, corrosion inhibitor, light stabilizer, UV absorber, polymerization inhibitor, silane coupling agent, inorganic or organic filler, metal powder, It can be added as appropriate depending on the application in which particles, foils, etc. are used.

  On the other hand, the pressure-sensitive adhesive layer of the present invention is obtained by crosslinking the pressure-sensitive adhesive composition as described above. The pressure-sensitive adhesive sheets of the present invention are formed by forming such a pressure-sensitive adhesive layer on a support. At that time, the pressure-sensitive adhesive composition is generally crosslinked after application of the pressure-sensitive adhesive composition, but it is also possible to transfer the pressure-sensitive adhesive layer comprising the crosslinked pressure-sensitive adhesive composition to a support or the like. is there.

In the case where a photopolymerization initiator as an optional component is added as described above, the pressure-sensitive adhesive composition is applied directly on the object to be protected, or after being applied to one or both sides of the support substrate, An adhesive layer can be obtained by light irradiation. Usually, the pressure-sensitive adhesive layer is obtained by irradiating ultraviolet rays having an illuminance of 1 to 200 mW / cm ² at a wavelength of 300 to 400 nm and photopolymerizing them with a light amount of about 400 to 4000 mJ / cm ² .

  The method for forming the pressure-sensitive adhesive layer on the film is not particularly limited. For example, the pressure-sensitive adhesive composition is applied to the support, and the pressure-sensitive adhesive layer is formed on the support by drying and removing the polymerization solvent. Produced. Thereafter, curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. In addition, when the pressure-sensitive adhesive composition is applied on a support to produce pressure-sensitive adhesive sheets, one or more solvents other than the polymerization solvent are newly added to the composition so that the pressure-sensitive adhesive composition can be uniformly applied on the support. You may add to.

  Moreover, as a formation method of the adhesive layer of this invention, the well-known method used for manufacture of adhesive sheets is used. Specific examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, extrusion coating using a die coater, and the like.

  The pressure-sensitive adhesive sheets of the present invention are usually prepared so that the pressure-sensitive adhesive layer has a thickness of 3 to 100 μm, preferably about 5 to 50 μm. The pressure-sensitive adhesive sheets are formed by applying the pressure-sensitive adhesive layer on one or both sides of various supports made of a plastic film such as a polyester film, or a porous material such as paper or nonwoven fabric, to form a sheet or tape. It is a form. Particularly in the case of a surface protective film, it is preferable to use a plastic substrate as a support.

  The thickness of the support constituting the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition of the present invention is usually 5 to 200 μm, preferably about 10 to 100 μm.

  If necessary, the support may be released with a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, silica powder, and the like, and an acid treatment, an alkali treatment, and a primer treatment. Further, easy adhesion treatment such as corona treatment, plasma treatment, and ultraviolet treatment, and antistatic treatment such as coating type, kneading type, and vapor deposition type can also be performed.

  The support is preferably a plastic base material having heat resistance and solvent resistance and flexibility. When the support has flexibility, the pressure-sensitive adhesive composition can be applied by a roll coater or the like, and can be wound into a roll.

  The plastic substrate is not particularly limited as long as it can be formed into a sheet shape or a film shape. For example, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene・ Polypropylene copolymer, ethylene / 1-butene copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, polyolefin film such as ethylene / vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, Polyester film such as polybutylene terephthalate, polyacrylate film, polystyrene film, nylon 6, nylon 6,6, polyamide film such as partially aromatic polyamide, polyvinyl chloride film, polyvinylidene chloride film, polymer film Such as carbonate film, and the like.

  In addition, the plastic substrate used in the present invention is more preferably an antistatic treatment.

  The antistatic treatment applied to the plastic substrate is not particularly limited, but there are a method of providing an antistatic layer on at least one side of a commonly used substrate and a method of kneading a type antistatic agent into a plastic substrate. Used. As a method of providing an antistatic layer on at least one surface of a base material, a method of applying an antistatic resin or a conductive polymer composed of an antistatic agent and a resin component, a conductive resin containing a conductive substance, or a conductive substance is used. Examples of the method include vapor deposition or plating.

  Antistatic agents contained in the antistatic resin include cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, primary, secondary and tertiary amino groups, and sulfonic acids Anionic antistatic agents having an anionic functional group such as salts, sulfate esters, phosphonates and phosphate esters, alkylbetaines and derivatives thereof, imidazolines and derivatives thereof, and amphoteric antistatic agents such as alanine and derivatives thereof Nonionic antistatic agents such as amino alcohol and derivatives thereof, glycerin and derivatives thereof, polyethylene glycol and derivatives thereof, and monomers having an ion conductive group of the above cation type, anion type and zwitterionic type are polymerized Or the ion conductive polymer obtained by copolymerization is mention | raise | lifted. These compounds may be used alone or in combination of two or more.

  As a cationic type antistatic agent, for example, it has a quaternary ammonium group such as alkyltrimethylammonium salt, acyloylamidopropyltrimethylammonium methosulfate, alkylbenzylmethylammonium salt, acylcholine chloride, polydimethylaminoethyl methacrylate (meth) Examples thereof include acrylate copolymers, styrene copolymers having quaternary ammonium groups such as polyvinylbenzyltrimethylammonium chloride, and diallylamine copolymers having quaternary ammonium groups such as polydiallyldimethylammonium chloride. These compounds may be used alone or in combination of two or more.

  Examples of the anionic antistatic agent include alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate ester salt, alkyl ethoxy sulfate ester salt, alkyl phosphate ester salt, and sulfonic acid group-containing styrene copolymer. These compounds may be used alone or in combination of two or more.

  Examples of zwitterionic antistatic agents include alkylbetaines, alkylimidazolium betaines, and carbobetaine graft copolymers. These compounds may be used alone or in combination of two or more.

  Nonionic antistatic agents include, for example, fatty acid alkylolamide, di (2-hydroxyethyl) alkylamine, polyoxyethylene alkylamine, fatty acid glycerin ester, polyoxyethylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid Examples thereof include esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl ethers, polyethylene glycols, polyoxyethylene diamines, copolymers composed of polyethers, polyesters and polyamides, and methoxypolyethylene glycol (meth) acrylates. These compounds may be used alone or in combination of two or more.

  Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene and the like. These compounds may be used alone or in combination of two or more.

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

  As the resin component used for the antistatic resin and the conductive resin, general-purpose resins such as polyester, acrylic, polyvinyl, urethane, melamine, and epoxy are used. In the case of a polymer type antistatic agent, it is not necessary to contain a resin component. Further, the antistatic resin component may contain a methylol- or alkylol-containing melamine-based, urea-based, glyoxal-based, acrylamide-based compound, epoxy compound, or isocyanate compound as a crosslinking agent.

  The antistatic layer can be formed by, for example, diluting the antistatic resin, conductive polymer, or conductive resin with a solvent such as an organic solvent or water, and applying and drying the coating liquid on a plastic substrate. It is formed.

  Examples of the organic solvent used for forming the antistatic layer include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, and isopropanol. can give. These solvents may be used alone or in combination of two or more.

  As a coating method in forming the antistatic layer, a known coating method is appropriately used. Specifically, for example, roll coating, gravure coating, reverse coating, roll brush, spray coating, air knife coating, impregnation and curtain coating are used. The law is raised.

  The thickness of the antistatic resin layer, the conductive polymer, and the conductive resin is usually about 0.01 to 5 μm, preferably about 0.03 to 1 μm.

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

  The thickness of the conductive material layer is usually 20 to 10,000 mm, preferably 50 to 5000 mm.

  As the kneading type antistatic agent, the above antistatic agent is appropriately used. The compounding amount of the kneading type antistatic agent is 20% by weight or less, preferably 0.05 to 10% by weight based on the total weight of the plastic substrate. The kneading method is not particularly limited as long as the antistatic agent can be uniformly mixed with the resin used for the plastic substrate. For example, a heating roll, a Banbury mixer, a pressure kneader, a biaxial kneader, etc. Used.

  In the pressure-sensitive adhesive sheets of the present invention, a separator can be bonded to the pressure-sensitive adhesive surface for the purpose of protecting the pressure-sensitive adhesive surface as necessary.

  As a material constituting the separator, there are paper and plastic film, but a plastic film is preferably used from the viewpoint of excellent surface smoothness. The film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer. Examples thereof include a coalesced film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 10 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as.

  The pressure-sensitive adhesive composition, the pressure-sensitive adhesive sheets, and the surface protective film using the present invention are particularly used for plastic products and the like that easily generate static electricity. For this reason, it becomes very useful as an antistatic surface protective film in a technical field related to optical and electronic components in which charging and contamination are particularly serious problems.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described, but the present invention is not limited to these. In addition, the evaluation item in an Example etc. measured as follows.

<Measurement of acid value>
The acid value was measured using an automatic titration apparatus (Hiranuma Sangyo Co., Ltd., COM-550), and was determined from the following formula.

A = {(Y−X) × f × 5.611} / M
A: Acid value Y: Titration volume of sample solution (ml)
X: Titration volume of a solution containing only 50 g of mixed solvent (ml)
f: Factor of titration solution M: Weight (g) of polymer sample.

The measurement conditions are as follows.
Sample solution: About 0.5 g of a polymer sample was dissolved in 50 g of a mixed solvent (toluene / 2-propanol / distilled water = 50 / 49.5 / 0.5, weight ratio) to obtain a sample solution.
Titration solution: 0.1N, 2-propanol potassium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd., for petroleum product neutralization value test)
Electrode: Glass electrode; GE-101, Comparative electrode; RE-201
Measurement mode: Petroleum product neutralization number test 1.

<Measurement of weight average molecular weight>
The weight part average molecular weight was measured using a GPC apparatus (HLC-8220GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.

Sample concentration: 0.2 wt% (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 pc.)
Detector: Differential refractometer (RI)
In addition, the weight part average molecular weight was calculated | required in the polystyrene conversion value.

<Measurement of glass transition temperature>
The glass transition temperature Tg (° C.) was determined by the following formula using the following literature values as the glass transition temperature Tgn (° C.) of the homopolymer of each monomer.

Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
[Wherein, Tg (° C.) is the glass transition temperature of the copolymer, Wn (−) is the weight fraction of each monomer, Tgn (° C.) is the glass transition temperature of the homopolymer of each monomer, and n is the type of each monomer Represents. ]
Literature values:
2-ethylhexyl acrylate: -70 ° C
2-hydroxyethyl acrylate: -15 ° C
Ethoxy-diethylene glycol acrylate: -70 ° C
Acrylic acid: 106 ° C.

<Measurement of Glass Transition Temperature (Tg) of Acrylic Polymer (F) Using Monomer Component with Unknown Literature Value>
About the glass transition temperature (Tg) (degreeC) of the obtained acrylic polymer (F), it determined by the dynamic viscoelasticity measurement in the following procedure.

  A sheet of acrylic polymer having a thickness of 20 μm was laminated to a thickness of about 2 mm, and this was punched to φ7.9 mm to produce a cylindrical pellet, which was used as a glass transition temperature (Tg) measurement sample.

  Using the above measurement sample, the measurement sample is fixed to a jig having a φ7.9 mm parallel plate, and the temperature dependence of the loss elastic modulus G ″ is measured by a dynamic viscoelasticity measuring device (ARES, manufactured by Rheometrics). The temperature at which the obtained G ″ curve was maximized was measured as the glass transition temperature (Tg) (° C.). The measurement conditions are as follows.

Measurement: Shear mode Temperature range: -70 ° C to 150 ° C
Temperature increase rate: 5 ° C / min
Frequency: 1Hz.

<Measurement of peeling voltage>
The pressure-sensitive adhesive sheet is cut to a size of 70 mm in width and 130 mm in length, the separator is peeled off, and then a polarizing plate bonded to an acrylic plate (thickness: 1 mm, width: 70 mm, length: 100 mm) previously neutralized. Nitto Denko Corporation SEG1425EWVAGS2B, width: 70 mm, length: 100 mm) The surface was crimped by a hand roller so that one end protruded 30 mm.

  After being left for one day in an environment of 23 ° C. × 50% RH, the sample was set at a predetermined position as shown in FIG. One end protruding 30 mm was fixed to an automatic winder, and peeled so that the peeling angle was 150 ° and the peeling speed was 10 m / min. The potential of the polarizing plate surface generated at this time was measured with a potential measuring device (KSD-0103, manufactured by Kasuga Denki Co., Ltd.) fixed at a predetermined position. The measurement was performed in an environment of 23 ° C. × 50% RH.

<Evaluation of contamination>
A 90 μm-thick triacetyl cellulose film (Fuji Photo Film, Fujitac) was cut to a width of 70 mm and a length of 100 mm, immersed in a 60 ° C. aqueous sodium hydroxide solution (10% by weight) for 1 minute, and then with distilled water. Washed to prepare an adherend.

  The prepared pressure-sensitive adhesive sheet was cut into a size of 50 mm in width and 80 mm in length, the separator was peeled off, and then the above adherend (washed with distilled water and allowed to stand in an environment of 23 ° C. × 50% RH for one day. Used) was laminated at a pressure of 0.25 MPa to prepare an evaluation sample.

After leaving the evaluation sample in an environment of 23 ° C. × 50% RH for one day, the pressure-sensitive adhesive sheet was peeled from the adherend by hand, and the contamination state of the adherend surface at that time was visually observed. The evaluation criteria are as follows.
If no contamination was found: ○
When contamination is recognized: x.

<Measurement of adhesive strength>
A triacetyl cellulose film (Fuji Photo Film Co., Ltd., Fujitack, thickness: 90 μm) was cut into a width of 70 mm and a length of 100 mm, immersed in an aqueous solution of sodium hydroxide (10 wt%) at 60 ° C. for 1 minute, and then in distilled water. To prepare an adherend.

  After the adherend was allowed to stand in an environment of 23 ° C. × 50% RH for 24 hours, an adhesive sheet cut to a width of 25 mm and a length of 100 mm was laminated to the adherend at a pressure of 0.25 MPa, and an evaluation sample was prepared. Produced.

  After the lamination, the laminate was allowed to stand for 30 minutes in an environment of 23 ° C. × 50% RH, and then the adhesive strength when peeled at a peeling speed of 10 m / min and a peeling angle of 180 ° was measured with a universal tensile tester. The measurement was performed in an environment of 23 ° C. × 50% RH.

<Preparation of (meth) acrylic polymer>
[Acrylic polymer (A)]
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, condenser, and dropping funnel, 180 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of ethoxy-diethylene glycol acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, polymerization As an initiator, 0.4 part by weight of 2,2′-azobisisobutyronitrile, 47 parts by weight of toluene, and 265 parts by weight of ethyl acetate were introduced, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was adjusted. A polymerization reaction was carried out for 6 hours while maintaining at around 65 ° C. to prepare an acrylic polymer (A) solution (40% by weight). The acrylic polymer (A) had a weight average molecular weight of 500,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 0.

[Acrylic polymer (B)]
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, condenser, and dropping funnel, 140 parts by weight of 2-ethylhexyl acrylate, 60 parts by weight of ethoxy-diethylene glycol acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, polymerization As an initiator, 0.4 part by weight of 2,2′-azobisisobutyronitrile, 94 parts by weight of toluene, and 218 parts by weight of ethyl acetate were introduced, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was adjusted. A polymerization reaction was carried out for 6 hours while maintaining the temperature at around 65 ° C. to prepare an acrylic polymer (B) solution (40% by weight). The acrylic polymer (B) had a weight average molecular weight of 500,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 0.

[Acrylic polymer (C)]
200 parts by weight of ethoxy-diethylene glycol acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, 2,2′- as a polymerization initiator in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, a cooler, and a dropping funnel Charge 0.4 parts by weight of azobisisobutyronitrile, 193 parts by weight of toluene, and 193 parts by weight of ethyl acetate, introduce nitrogen gas with gentle stirring, and maintain the liquid temperature in the flask at around 65 ° C. for 6 hours. A polymerization reaction was performed to prepare an acrylic polymer (C) solution (40% by weight). The acrylic polymer (C) had a weight average molecular weight of 440,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 0.

[Acrylic polymer (D)]
200 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, 2,2′- as a polymerization initiator in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, a cooler, and a dropping funnel Charge 0.4 parts by weight of azobisisobutyronitrile and 312 parts by weight of ethyl acetate, introduce nitrogen gas while gently stirring, perform the polymerization reaction for 6 hours while keeping the liquid temperature in the flask at around 65 ° C., An acrylic polymer (D) solution (40% by weight) was prepared. The acrylic polymer (D) had a weight average molecular weight of 540,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 0.

[Acrylic polymer (E)]
As a polymerization initiator, 140 parts by weight of 2-ethylhexyl acrylate, 60 parts by weight of ethoxy-diethylene glycol acrylate, 4 parts by weight of acrylic acid in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, a condenser, and a dropping funnel Charge 0.4 parts by weight of 2,2′-azobisisobutyronitrile, 47 parts by weight of toluene, and 265 parts by weight of ethyl acetate, introduce nitrogen gas while gently stirring, and maintain the liquid temperature in the flask at around 65 ° C. Then, a polymerization reaction was carried out for 6 hours to prepare an acrylic polymer (E) solution (40% by weight). The acrylic polymer (E) had a weight average molecular weight of 720,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 15.

[Acrylic polymer (F)]
190 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of ethoxy-diethylene glycol acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, polymerization in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, a condenser, and a dropping funnel As an initiator, 0.4 part by weight of 2,2′-azobisisobutyronitrile and 312 parts by weight of ethyl acetate were added, and nitrogen gas was introduced while gently stirring to keep the liquid temperature in the flask at around 65 ° C. Then, a polymerization reaction was performed for 6 hours to prepare an acrylic polymer (F) solution (40% by weight). The acrylic polymer (F) had a weight average molecular weight of 670,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 0.

[Acrylic polymer (G)]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, a condenser, and a dropping funnel, 180 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of methoxy-dipropylene glycol acrylate, 8 parts by weight of 2-hydroxyethyl acrylate Then, 0.4 part by weight of 2,2′-azobisisobutyronitrile and 386 parts by weight of ethyl acetate were added as a polymerization initiator, and nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was around 65 ° C. Then, a polymerization reaction was carried out for 6 hours to prepare an acrylic polymer (G) solution (35% by weight). The acrylic polymer (G) had a weight average molecular weight of 410,000, a glass transition temperature (Tg) of 0 ° C. or lower, and an acid value of 0.

<Preparation of antistatic agent solution>
[Antistatic agent solution (a)]
A four-necked flask equipped with a stirring blade, thermometer, condenser, and dropping funnel was charged with 5 parts by weight of lithium iodide and 20 parts by weight of ethyl acetate, and the mixture was stirred for 2 hours while maintaining the liquid temperature in the vicinity of 25 ° C. To prepare an antistatic agent solution (a) (20% by weight).

[Antistatic agent solution (b)]
A four-necked flask equipped with a stirring blade, thermometer, condenser, and dropping funnel was charged with 5 parts by weight of lithium bis (pentafluoroethanesulfonyl) imide and 20 parts by weight of ethyl acetate, and the liquid temperature in the flask was kept at around 25 ° C. The mixture was mixed and stirred for 2 hours to prepare an antistatic agent solution (b) (20% by weight).

[Antistatic agent solution (c)]
In a four-necked flask equipped with a stirring blade, thermometer, condenser, and dropping funnel, 0.1 part by weight of lithium iodide, 7.9 parts by weight of polypropylene glycol (diol type, number average molecular weight 2000), 8 parts by weight of ethyl acetate The mixture was stirred for 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to prepare an antistatic agent solution (c) (50% by weight).

[Antistatic agent solution (d)]
A four-necked flask equipped with a stirring blade, a thermometer, a condenser, and a dropping funnel, 0.1 part by weight of lithium iodide, a block copolymer of polyethylene glycol-polypropylene glycol-polyethylene glycol (Daiichi Kogyo Seiyaku Co., Ltd., Epan 450, number average molecular weight 2400, ethylene glycol ratio: 50% by weight) 9.9 parts by weight and 10 parts by weight of ethyl acetate were charged, and the mixture was stirred for 2 hours while keeping the liquid temperature in the vicinity of 80 ° C. An agent solution (d) (50% by weight) was prepared.

<Preparation of antistatic treatment film>
Antistatic by diluting 10 parts by weight of an antistatic agent (manufactured by Solvex, Microsolver RMd-142, mainly composed of tin oxide and polyester resin) with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol An agent solution was prepared.

  The obtained antistatic agent solution was applied onto a polyethylene terephthalate (PET) film (thickness 38 μm) using a Meyer bar and dried at 130 ° C. for 1 minute to remove the solvent and remove the antistatic layer (thickness). 0.2 μm) to form an antistatic film.

<Example 1>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted with ethyl acetate to 20% by weight, and 0.4 parts by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. Trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L, 75 wt% ethyl acetate solution) as an agent, dibutyltin dilaurate (1 wt% ethyl acetate solution) as a crosslinking catalyst ) 0.6 part by weight was added and mixed and stirred to prepare an acrylic pressure-sensitive adhesive solution (1).

[Preparation of adhesive sheet]
The said acrylic adhesive solution (1) was apply | coated to the surface opposite to the antistatic process surface of said antistatic process film, and it heated at 110 degreeC for 3 minute (s), and formed the 20-micrometer-thick adhesive layer. Next, a silicone-treated surface of a polyethylene terephthalate film having a thickness of 25 μm having one surface subjected to silicone treatment was bonded to the surface of the pressure-sensitive adhesive layer to produce a pressure-sensitive adhesive sheet.

<Example 2>
(Preparation of adhesive solution)
An acrylic pressure-sensitive adhesive solution (in the same manner as in Example 1 except that the acrylic polymer (B) solution (40% by weight) was used instead of the acrylic polymer (A) solution (40% by weight). 2) was produced.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (2) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Example 3>
(Preparation of adhesive solution)
The acrylic polymer (C) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.7 parts by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and mixed to prepare an acrylic pressure-sensitive adhesive solution (3).

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (3) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Example 4>
(Preparation of adhesive solution)
Example 3 except that 0.7 parts by weight of the antistatic agent solution (b) (20% by weight) was used instead of 0.7 part by weight of the antistatic agent solution (a) (20% by weight). An acrylic pressure-sensitive adhesive solution (4) was prepared by the same method as described above.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (4) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Comparative Example 1>
(Preparation of adhesive solution)
The acrylic polymer (D) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and dialkylsulfosuccinate sodium salt (Daiichi Kogyo Seiyaku Co., Ltd.) which is an anionic surfactant is added to 100 parts by weight of this solution. , Neocor P) 2.0 parts by weight, trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L, 75% by weight ethyl acetate solution) as a crosslinking agent, crosslinking catalyst As a mixture, 0.6 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) was added and mixed and stirred to prepare an acrylic pressure-sensitive adhesive solution (5).

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (5) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Comparative Example 2>
(Preparation of adhesive solution)
The acrylic polymer (D) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 3.2 parts by weight of the antistatic agent solution (c) (50% by weight) is added to 100 parts by weight of this solution. 0.4 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) as an agent and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst were mixed and stirred. An acrylic pressure-sensitive adhesive solution (6) was prepared.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (6) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Comparative Example 3>
(Preparation of adhesive solution)
An acrylic pressure-sensitive adhesive solution (7) was prepared in the same manner as in Example 1 except that the antistatic agent solution (a) was not used.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (7) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Comparative Example 4>
(Preparation of adhesive solution)
The acrylic polymer (E) solution (40% by weight) is diluted with ethyl acetate to 20% by weight, and 0.7 parts by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 0.7 parts by weight of 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad C) was added and mixed and stirred to prepare an acrylic pressure-sensitive adhesive solution (8). did.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (8) was used in place of the acrylic pressure-sensitive adhesive solution (1).

<Example 5>
(Preparation of adhesive solution)
The acrylic polymer (F) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 2.8 parts by weight of the antistatic agent solution (d) (50% by weight) is added to 100 parts by weight of this solution. Hexamethylene diisocyanate isocyanurate (Nihon Polyurethane Kogyo Co., Ltd., Coronate HX) 0.3 parts by weight as the agent, dibutyltin dilaurate (1 wt% ethyl acetate solution) 0.4 parts by weight as the crosslinking catalyst, normal temperature (25 The mixture was stirred and stirred for about 1 minute to prepare an acrylic pressure-sensitive adhesive solution (9).

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (9) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Example 6>
(Preparation of adhesive solution)
The acrylic polymer (G) solution (35% by weight) is diluted to 20% by weight with ethyl acetate, and 4 parts by weight of the antistatic agent solution (d) (50% by weight) is added to 100 parts by weight of this solution as a crosslinking agent. 0.4 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst were added at room temperature (25 ° C.). Under stirring for about 1 minute, an acrylic pressure-sensitive adhesive solution (10) was prepared.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (10) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Comparative Example 5>
(Preparation of adhesive solution)
The acrylic polymer (D) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 2.8 parts by weight of the antistatic agent solution (d) (50% by weight) is added to 100 parts by weight of this solution. 0.4 parts by weight of an isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) was added as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1 wt% ethyl acetate solution) was added as a crosslinking catalyst. The mixture was stirred and stirred for about 1 minute to prepare an acrylic pressure-sensitive adhesive solution (11).

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (11) was used instead of the acrylic pressure-sensitive adhesive solution (1).

  According to the said method, the peeling voltage of the produced adhesive sheet was measured, contamination | pollution property evaluation, and the adhesive force were measured. The obtained results are shown in Table 1.

  From the results of Table 1 above, when the pressure-sensitive adhesive composition containing, as a base polymer, an acrylic polymer having a (meth) acrylic acid alkylene oxide adduct prepared according to the present invention was used (Examples 1 to 6), Also in the examples, it was clarified that the absolute value of the peeling band voltage of the polarizing plate was suppressed to a low value of less than 1.0 kV, and there was no contamination on the polarizing plate as the adherend.

  On the other hand, in the case where the (meth) acrylic acid alkylene oxide adduct is not contained (Comparative Examples 1-2, 5), although the stripping band voltage is kept low, the occurrence of contamination to the polarizing plate occurs. Admitted. Moreover, when it contains the (meth) acrylic-acid alkylene oxide adduct but does not contain an alkali metal salt (Comparative Example 3), and the case where the (meth) acrylic-type polymer whose acid value is larger than 10 is used ( In Comparative Example 4), although no contamination to the polarizing plate was observed, the absolute value of the peeling band voltage was a high value of −1.0 kV or more. Therefore, in all of the comparative examples, it is apparent that the suppression of the stripping voltage and the suppression of the occurrence of contamination on the polarizing plate cannot be performed side by side, which is not suitable for the pressure-sensitive adhesive composition for the antistatic pressure-sensitive adhesive sheet. It became.

  Moreover, the adhesive sheets of Examples 1 to 4 of the present invention have a 180 ° peel adhesive strength at a peeling speed of 10 m / min in the range of 0.1 to 6 N / 25 mm, and are used for a re-peelable surface protective film. It turns out that it is an applicable adhesive sheet.

Therefore, it can be confirmed that the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition having excellent adhesion reliability, having excellent antistatic properties when peeled and having reduced contamination to the protected body. It was.

Claims (5)

5 to 100% by weight of (meth) acrylic acid alkylene oxide adduct, 0 to 95% by weight of (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms other than the above, and other polymerizable monomers 0 to 95 A pressure-sensitive adhesive composition comprising a (meth) acrylic polymer having a weight percent as a monomer component, an alkali metal salt, and an ether group-containing compound,
The acid value of the (meth) acrylic polymer is 10 or less,
The pressure-sensitive adhesive composition comprising 0.01 to 20 parts by weight of the ether group-containing compound with respect to 100 parts by weight of the (meth) acrylic polymer.   The pressure-sensitive adhesive composition according to claim 1, wherein the alkali metal salt is a lithium salt.   The adhesive layer formed by bridge | crosslinking the adhesive composition in any one of Claims 1-2.   A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition according to claim 1 on one side or both sides of a support.   A surface protective film comprising a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition according to claim 1 on one or both sides of a support.