JP2005306937A - Adhesive composition, and adhesive sheets - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antistatic adhesive composition which does not cause corrosion, even when the adhesive surface of the composition is brought into direct contact with a metal, and has excellent anti-staticity, and to provide an antistatic adhesive sheet using the same. <P>SOLUTION: This adhesive composition comprising a (meth)acrylic polymer containing a (meth)acrylic monomer having a 1 to 14C alkyl group as a main component is characterized in that the acid value of the (meth)acrylic polymer is ≤29 and a fluorine-containing lithium imide salt is contained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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 and pressure-sensitive adhesive sheets 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 are particularly useful as antistatic pressure-sensitive adhesive sheets in applications that require corrosion resistance such as electronic equipment.

  The pressure-sensitive adhesive sheets can be bonded by applying a slight pressure at room temperature for a short time, and are used in various applications for joining various articles. In addition, the pressure-sensitive adhesive sheets have cohesive strength and elasticity, so that they can be bonded appropriately, but can be peeled off from a hard smooth surface, and are also used as a surface protective film.

  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, an optical member such as a polarizing plate or a wave plate used for a liquid crystal display panel is formed by bonding a surface protective film to the optical member via an adhesive layer. As the surface protective film used for these optical members, a separator is generally used for the purpose of protecting the adhesive surface. And this separator peels and removes, when bonding a surface protection film to an optical member.

  In general, a protective film, a pressure-sensitive adhesive, and a separator that constitute a surface protective film are made of a plastic material and thus have high electrical insulation, and static electricity is generated during friction and peeling. Accordingly, static electricity is generated when the separator is peeled off from the surface protective film. The static electricity generated at the time of peeling causes a problem that dust adheres to the surface protection film and contaminates the optical member. Therefore, various antistatic treatments are applied to the surface protective film in order to prevent such 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 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, LiClO ₄ shown in such a proposal is highly corrosive and may corrode the metal when the adhesive surface directly touches the metal. In particular, as a use application of a protective film for an optical member, there are many examples in which the outer peripheral portion of the optical member is applied to a liquid crystal module fixed with a metal fixing frame called stainless steel or aluminum called a “bezel”. In applications, there is a possibility that the “bezel” may be deteriorated due to corrosion by the above-mentioned pressure-sensitive adhesive component, and there are restrictions on application.

As described above, none of these problems can still be solved in a balanced manner, and in the technical field related to electronic equipment where static charge and corrosion are particularly serious problems, antistatic surfaces It is difficult to respond to further improvement requests for protective films.
JP-A-9-165460 JP-A-6-128539

  Therefore, the object of the present invention is to eliminate the problems in the conventional antistatic pressure-sensitive adhesive sheets, so that corrosion does not occur even when the adhesive surface is in direct contact with metals, and the antistatic property at the time of peeling is excellent. An object of the present invention is to provide an antistatic pressure-sensitive adhesive composition and an antistatic pressure-sensitive adhesive sheet using the same.

  As a result of intensive studies on the base polymer of the pressure-sensitive adhesive composition in order to achieve the above object, the present inventors have found that a pressure-sensitive adhesive containing a (meth) acrylic polymer having an acid value of 29 or less and a fluorine-containing lithium imide salt. By using the agent composition, it was found that an antistatic pressure-sensitive adhesive composition having an antistatic property when peeled and having reduced corrosiveness to the protected body was obtained, and the present invention was completed. .

  That is, the present invention provides a pressure-sensitive adhesive composition containing a (meth) acrylic polymer having a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component, and the (meth) acrylic polymer It has an acid value of 29 or less and includes a fluorine-containing lithium imide salt.

  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, by using a pressure-sensitive adhesive composition containing a (meth) acrylic polymer having an acid value of 29 or less and a fluorine-containing lithium imide salt, Corrosion does not occur even when the adhesive surface is in direct contact with metals, and it has excellent anti-static properties at the time of peeling. Although the details of the reason why the crosslinked product of the pressure-sensitive adhesive composition exhibits such properties are not clear, the pressure-sensitive adhesive includes the (meth) acrylic polymer having the acid value of 29 or less and the fluorine-containing lithium imide salt. By using the composition, it contributes to a balanced interaction such as compatibility with the fluorine-containing lithium imide salt, conductivity, etc., and thus enables good adhesion characteristics, charging characteristics and corrosivity to be aligned. Guessed.

  In the pressure-sensitive adhesive composition according to the present invention, the (meth) acrylic polymer containing a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component, It includes a (meth) acrylic polymer having an acid value of 29 or less. The acid value is preferably 20 or less, and more preferably 16 or less. 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 having a large acid value, there are a large number of carboxyl groups and sulfonate groups having a large interaction with the fluorine-containing lithium imide salt. It is presumed that conduction is hindered and excellent antistatic ability cannot be obtained. In the case of the (meth) acrylic polymer having an acid value exceeding 29, an excellent antistatic ability may not be obtained.

  In the present invention, a (meth) acrylic polymer having a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component and a fluorine-containing lithium imide in order to exert an action as an adhesive composition A salt is at least a constituent component. By using a (meth) acrylic polymer whose main component is a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, there is a balance of compatibility with a fluorine-containing lithium imide salt and excellent adhesive properties. It is estimated that it contributes to the parallel.

  The pressure-sensitive adhesive composition according to the present invention includes a fluorine-containing lithium imide salt. Adhesive with high anti-static properties when peeled and no corrosion on metal by obtaining compatibility and balanced interaction with (meth) acrylic polymer using fluorine-containing lithium imide salt A composition can be obtained. The fluorine-containing lithium imide salt refers to a lithium imide salt containing a fluorine atom in the molecular structure.

  On the other hand, the pressure-sensitive adhesive layer of the present invention is formed by crosslinking the pressure-sensitive adhesive composition described above. A pressure-sensitive adhesive sheet 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 sheet 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 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 the corrosiveness to the object to be protected. It becomes the made adhesive sheets. For this reason, in particular, it becomes very useful as an antistatic surface protective film in a technical field related to electronic equipment, in which electrostatic charging and corrosiveness are particularly serious problems.

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

  The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing a (meth) acrylic polymer having a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component. The acid value of the polymer is 29 or less, and includes a fluorine-containing lithium imide salt.

  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.

  Although the (meth) acrylic-type monomer which has a C1-C14 alkyl group in this invention is used, the (meth) acrylic-type monomer which has a C4-C14 alkyl group is preferable. Examples thereof include methyl (meth) acrylate and ethyl (meth) acrylate. Among them, n-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 or the like is preferably used. These acrylic monomers may be used alone or in combination of two or more.

  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. These monomers may be used alone or in combination, but the total content is less than 50% by weight in the monomer component of the (meth) acrylic monomer.

  Other polymerizable monomers used in (meth) acrylic polymers include, for example, cohesion and heat resistance of sulfonic acid group-containing monomers, phosphate group-containing monomers, cyano group-containing monomers, vinyl ester monomers, aromatic vinyl monomers, etc. It works as an adhesion-improving component, carboxyl group-containing monomer, acid anhydride group-containing monomer, amide group-containing monomer, amino group-containing monomer, epoxy group-containing monomer, N-acryloylmorpholine, vinyl ether monomer, etc. A component having a functional group can be appropriately used. These monomer compounds may be used alone or in admixture of two or more. However, when an acrylate and / or methacrylate having an acid functional group such as a carboxyl group, a sulfonic acid group, or a phosphoric acid group is used, it is necessary to adjust the acid value of the acrylic polymer to be 29 or less. When the acid value of the acrylic polymer exceeds 29, the charging characteristics are deteriorated, which is not preferable. An example of the acrylic polymer having an acid value of 29 or less is, for example, an acrylic polymer obtained by copolymerizing 2-ethylhexyl acrylate and acrylic acid as an acrylic polymer having a carboxyl group. It shows that acrylic acid is 3.7 parts by weight or less with respect to 100 parts by weight of the total amount of acrylate and acrylic acid.

  Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth And acryloyloxynaphthalene sulfonic acid.

  Examples of the phosphoric acid group-containing monomer include 2-hydroxyethylacryloyl phosphate.

  Examples of the cyano group-containing monomer include acrylonitrile.

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

  Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethyl styrene, α-methyl styrene, and the like.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid.

  Examples of the acid anhydride group-containing monomer include maleic anhydride and itaconic anhydride.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 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 vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like.

  Examples of the amide group-containing monomer include acrylamide and diethyl acrylamide.

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

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

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

  The (meth) acrylic polymer in the present invention is obtained by using 50 to 100% by weight of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms in all monomer components.

  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, more preferably 300,000 to 3,000,000. When the weight average molecular weight is less than 100,000, the adhesive strength at the time of peeling increases due to the improvement of wettability to the polarizing plate, which may cause damage to the polarizing plate in the peeling process. There is a tendency for adhesive residue to occur due to the reduced cohesive force. 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 surface protective film 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 surface protective film. 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. In addition, the obtained copolymer may be any of a random copolymer, a block copolymer, and the like.

Examples of the fluorine-containing lithium imide salt used in the present invention include LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (C ₄ F ₉ SO ₂ ) (CF ₃ SO ₂ ), _{LiN (C 8 F 17 SO 2} ) (CF 3 SO 2), LiN (CF 3 CH 2 OSO 2) 2, LiN (CF 3 CF 2 CH 2 OSO 2) 2, LiN (HCF 2 CF 2 CH 2 OSO 2 ) ₂ , LiN ((CF ₃ ) ₂ CHOSO ₂ ) ₂ . Among these, LiN (C ₂ F ₅ SO ₂ ) ₂ is particularly preferable because particularly excellent charging characteristics can be obtained. These fluorine-containing lithium imide salts may be used alone or in admixture of two or more.

  As a compounding quantity of the said fluorine-containing lithium imide salt, it is 0.01-5 weight part with respect to 100 weight part of (meth) acrylic-type polymers, Preferably it is 0.05-3 weight part. If the amount is less than 0.01 part by weight, it is difficult to obtain sufficient charging characteristics, and if it exceeds 5 parts by weight, contamination of the adherend may 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. Of these, isocyanate compounds and epoxy compounds 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 commercially available 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, N, N′-methylenebisacrylamide and the like.

  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 use application as the pressure-sensitive adhesive sheet. In general, in order to obtain sufficient heat resistance by the cohesive force of the acrylic pressure-sensitive adhesive, it is preferably blended at 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, benzyl dimethyl 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-ethylthio Thioxanthones such as xanthone 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, α-acyloxime ester, and the like. 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, and 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, 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-dimethylaminoethyl benzoate, 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 0.1-7 weight part.

  In the pressure-sensitive adhesive composition of the present invention, polyether polyol may be appropriately added as an optional component for the purpose of further improving the antistatic effect on the adherend.

  The polyether polyol is not particularly limited as long as it is a polymer polyol having an ether group. For example, polyethylene glycol, polypropylene glycol (diol type), polypropylene glycol (triol type), polytetramethylene ether glycol, and the above derivatives And a copolymer. Among these, polypropylene glycol (diol type) and polypropylene glycol (triol type) are particularly preferably used. These polyether polyols may be used alone or in combination of two or more.

  As the molecular weight of the polyether polyol, those having a number average molecular weight of 10,000 or less, preferably 200 to 5,000 are suitably used. When the molecular weight is 10,000 or more, the contamination of the adherend increases.

  The amount of the polyether polyol is 1 to 50 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the acrylic polymer. If the amount is less than 1 part by weight, sufficient charging characteristics cannot be obtained, and if it exceeds 50 parts by weight, contamination of the adherend increases.

  Furthermore, the pressure-sensitive adhesive composition used for the protective film of the present invention may contain other known additives, such as powders such as colorants and pigments, surfactants, plasticizers, and adhesiveness. Additives, low molecular weight polymers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillers, metal powders, particles It can be added as appropriate depending on the application in which the shape or foil is 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 surface protective film of the present invention is formed by forming such an adhesive layer on a support film. At that time, the pressure-sensitive adhesive composition is generally crosslinked after application of the pressure-sensitive adhesive composition, but the pressure-sensitive adhesive layer comprising the crosslinked pressure-sensitive adhesive composition can be transferred to a support film 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 a support film, and the polymerization solvent is dried and formed to form the pressure-sensitive adhesive layer on the support film. 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 a pressure-sensitive adhesive composition is applied on a support film to produce a surface protective film, one or more solvents other than the polymerization solvent are newly added to the composition so that the surface protective film can be uniformly applied on the support film. May be added.

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

  The pressure-sensitive adhesive sheets of the present invention are usually prepared so that the thickness of the pressure-sensitive adhesive layer is usually 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, a plastic substrate is used as a support.

  The support film constituting the surface protective film is preferably a resin film having heat resistance and solvent resistance and flexibility. When the support film 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.

  The thickness of the film is usually about 5 to 200 μm, preferably about 10 to 100 μm. The adhesive layer bonding surface of the film may be appropriately treated with a release agent such as a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, silica powder, or the like.

  For plastic substrates, silicone, fluorine, long chain alkyl or fatty acid amide release agents, release with silica powder, antifouling treatment, acid treatment, alkali treatment, primer, etc. Anti-adhesive treatment such as treatment, corona treatment, plasma treatment, and ultraviolet treatment, coating type, kneading type, and vapor deposition type can also be performed.

  In addition, in order to improve the adhesiveness between an adhesive layer and a support film, you may perform corona treatment etc. on the surface of a support film. Moreover, you may perform a back surface process to a support film.

  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 base 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.

  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 the above-mentioned cationic, anionic and zwitterionic ion conductive groups 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.

  Examples of the cationic antistatic agent include a quaternary ammonium group such as alkyltrimethylammonium salt, acyloylamidopropyltrimethylammonium methosulfate, alkylbenzylmethylammonium salt, acylcholine chloride, polydimethylaminoethyl methacrylate (meta ) Acrylate copolymer, styrene copolymer having quaternary ammonium group such as polyvinylbenzyltrimethylammonium chloride, diallylamine copolymer having quaternary ammonium group 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 the zwitterionic antistatic agent include alkylbetaines, alkylimidazolium betaines, and carbobetaine graft copolymers. These compounds may be used alone or in combination of two or more.

  Examples of the nonionic antistatic agent include fatty acid alkylolamide, di (2-hydroxyethyl) alkylamine, polyoxyethylene alkylamine, fatty acid glycerin ester, polyoxyethylene glycol fatty acid ester, sorbitan fatty acid ester, and polyoxysorbitan. Examples thereof include fatty acid esters, polyoxyethylene alkylphenyl 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 conductive polymers 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, and cobalt. , 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. Formed with.

  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. Specific examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, impregnation and curtain coating methods.

  The thickness of the antistatic 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, or the like can be used. Used.

  The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet using the present invention are particularly used for plastic products and the like that are likely to generate static electricity, and in particular, antistatic properties in applications requiring corrosion resistance such as electronic equipment. It can be used as an adhesive sheet.

  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 weight average molecular weight of acrylic polymer>
The weight average molecular weight of the produced polymer was measured by GPC (gel permeation chromatography).

Device: HLC-8220GPC, manufactured by Tosoh Corporation
column:
Sample column: manufactured by Tosoh Corporation, TSK guard column Super HZ-H (1) + TSK gel Super HZM-H (2)
Reference column; manufactured by Tosoh Corporation, TSKgel Super H-RC (1)
Flow rate: 0.6ml / min
Injection volume: 10 μl
Column temperature: 40 ° C
Eluent: THF
Injection sample concentration: 0.2% by weight
Detector: differential refractometer The weight average molecular weight was calculated in terms of polystyrene.

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

Formula: 1 / (Tg + 273) = Σ [W _n / (Tg _n +273)]
(Wherein Tg (° C.) is the glass transition temperature of the copolymer, W _n (−) is the weight fraction of each monomer, T g _n (° C.) is the glass transition temperature of the homopolymer of each monomer, and n is each monomer. Represents the type of
2-ethylhexyl acrylate: -70 ° C
2-hydroxyethyl acrylate: -15 ° C
Butyl acrylate: -55 ° C
Acrylic acid: 106 ° C
In addition, as a reference value, “Synthesis / design of acrylic resin and development of new application” (published by Central Management Development Center Publishing Department) was referred.

<Measurement of acid value>
The acid value was measured using an automatic titration device (COM-550, manufactured by Hiranuma Sangyo Co., Ltd.) and obtained 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 of polymer sample (g)
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 (weight ratio: toluene / 2-propanol / distilled water = 50 / 49.5 / 0.5) to obtain a sample solution.

Titration solution: 2-propanol potassium hydroxide solution (0.1N, 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 peeling voltage>
A protective film 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 (manufactured by Nitto Denko Co., Ltd.) bonded to an acrylic plate having a thickness of 1 mm, a width of 70 mm, and a length of 100 mm that has been previously neutralized. SEG1425EWVAGS2B, size: width 70 mm, length 100 mm) The surface was crimped with a hand roller so that one end of the surface protruded 30 mm. After being left for one day in an environment of 23 ° C. × 50% RH, a sample was set at a predetermined position as shown below. 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 peeled adhesive sheet was placed on a sample fixing base, and the potential of the adhesive surface 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.

<Corrosive evaluation>
The pressure-sensitive adhesive sheet was cut into a size of 30 mm in width and 80 mm in length, and pressure-bonded to an aluminum foil having a width of 50 mm and a length of 100 mm with a hand roller to obtain an evaluation sample. This evaluation sample was left in an environment of 60 ° C. × 90% RH for one day, and then the protective film was peeled off from the aluminum foil, and the aluminum foil surface was visually observed and evaluated.

When no discoloration was observed: ○
When discoloration is observed: ×

<Measurement of adhesive strength>
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 above adherend was allowed to stand for 1 day in an environment of 23 ° C. × 50% RH, and then an adhesive sheet cut to a size of 25 mm in width and 100 mm in length was laminated at a pressure of 0.25 MPa to prepare an evaluation sample. After standing for 30 minutes after lamination, the adhesive strength when peeled at a peeling speed of 10 m / min 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)]
200 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, and 2,2′-azobisisobutyrate as a polymerization initiator are added to a four-flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube and a condenser. Charge 0.4 parts by weight of nitrile and 312 parts by weight of ethyl acetate, introduce nitrogen gas while gently stirring, and perform a polymerization reaction for about 6 hours while maintaining the liquid temperature in the flask at around 65 ° C. (A) A solution (40% by weight) was prepared. 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 0.0.

[Acrylic polymer (B)]
200 parts by weight of butyl acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, and 2,2′-azobisisobutyronitrile as a polymerization initiator in a four-flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube and a condenser 0.4 parts by weight and 625 parts by weight of ethyl acetate were added, nitrogen gas was introduced while gently stirring, and the polymerization temperature was kept at around 65 ° C. for about 6 hours to carry out a polymerization reaction. ) A solution (25% by weight) was prepared. The acrylic polymer (B) had a weight average molecular weight of 540,000, a glass transition temperature (Tg) of −54 ° C., and an acid value of 0.0.

[Acrylic polymer (C)]
200 parts by weight of 2-ethylhexyl acrylate, 4 parts by weight of acrylic acid and 2,2′-azobisisobutyronitrile as a polymerization initiator were added to a four-flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser. .4 parts by weight and 312 parts by weight of ethyl acetate were charged, nitrogen gas was introduced with gentle stirring, and the polymerization temperature was kept at around 65 ° C. for about 6 hours to carry out the polymerization reaction. Acrylic polymer (C) A solution (40% by weight) was prepared. The acrylic polymer (C) had a weight average molecular weight of 530,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 15.

[Acrylic polymer (D)]
200 parts by weight of 2-ethylhexyl acrylate and 1-hydroxycyclohexyl phenyl ketone as a polymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals) in a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser 0.1 part by weight, 0.1 part by weight of benzyl methyl ketal (Ciba Specialty Chemicals, Irgacure 651) were charged, nitrogen gas was introduced while gently stirring, and a high-pressure mercury lamp (SHL-, manufactured by Toshiba Lighting & Technology Corp.) was introduced. A polymerization reaction was carried out by irradiating with 100 UVQ-2) for about 3 minutes to prepare an acrylic polymer (D) solution that was a partially polymerized product (syrup-like) with a polymerization rate of 10%. The acrylic polymer (D) had a weight average molecular weight of 2.2 million, a glass transition temperature (Tg) of −70 ° C., and an acid value of 0.0.

[Acrylic polymer (E)]
200 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of acrylic acid and 2,2′-azobisisobutyronitrile 0 as a polymerization initiator were added to a four-flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser. .4 parts by weight and 312 parts by weight of ethyl acetate were charged, nitrogen gas was introduced with gentle stirring, and the polymerization temperature was kept at around 65 ° C. for about 6 hours to carry out the polymerization reaction. Acrylic polymer (E) A solution (40% by weight) was prepared. The acrylic polymer (E) had a weight average molecular weight of 540,000, a glass transition temperature (Tg) of −66 ° C., and an acid value of 30.

<Preparation of antistatic agent solution>
[Antistatic agent solution (a)]
A four-necked flask equipped with a stirring blade, a thermometer, and a cooler was charged with 5 parts by weight of LiN (C ₂ F ₅ SO ₂ ) _{2 and} 20 parts by weight of ethyl acetate, and nitrogen gas was introduced into the flask while gently stirring. The mixture was stirred for about 2 hours while keeping the liquid temperature around 25 ° C. to prepare an antistatic agent solution (a) (20% by weight).

[Antistatic agent solution (b)]
In a four-flask equipped with a stirring blade, a thermometer and a condenser, 0.5 part by weight of LiN (C ₂ F ₅ SO ₂ ) ₂ , 9.5 parts by weight of polypropylene glycol (diol type, number average molecular weight 2000), ethyl acetate Charge 10 parts by weight, introduce nitrogen gas while gently stirring, keep the liquid temperature in the flask at around 80 ° C., mix and stir for about 2 hours, and add antistatic agent solution (b) (50% by weight) Prepared.

[Antistatic agent solution (c)]
A four-flask equipped with a stirring blade, a thermometer, and a condenser was charged with 5 parts by weight of lithium perchlorate and 20 parts by weight of ethyl acetate, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was 25 ° C. The mixture was stirred and stirred for about 2 hours to prepare an antistatic agent solution (c) (20% by weight).

[Antistatic agent solution (d)]
A four-flask equipped with a stirring blade, a thermometer and a condenser was charged with 0.2 parts by weight of lithium perchlorate, 9.8 parts by weight of polypropylene glycol (diol type, number average molecular weight 2000), and 10 parts by weight of ethyl acetate. Nitrogen gas was introduced while gently stirring, and the mixture was stirred for about 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to prepare an antistatic agent solution (d) (50 wt%).

<Example 1>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 1.0 part by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 1.1 parts by weight of a trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L) as an agent, and 0.6 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst In addition, the mixture was stirred at about 25 ° C. for about 1 minute to prepare an acrylic pressure-sensitive adhesive solution (1).

[Preparation of adhesive sheet]
The acrylic pressure-sensitive adhesive solution (1) was applied to one side of a polyethylene terephthalate film and heated at 110 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 20 μm. Next, a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) having a silicone treatment on one side was bonded to the surface of the pressure-sensitive adhesive layer to produce a pressure-sensitive adhesive sheet.

<Example 2>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 100 parts by weight of this solution is charged with 4.0 parts by weight of the antistatic agent solution (b) (50% by weight). 0.53 parts by weight of a trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst In addition, the mixture was stirred at about 25 ° C. for about 1 minute to prepare an acrylic pressure-sensitive adhesive solution (2).

[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 pressure-sensitive adhesive solution (B) (25% by weight) was replaced with 100% by weight of the acrylic pressure-sensitive adhesive solution (A) (40% by weight) diluted to 20% by weight with ethyl acetate. An acrylic pressure-sensitive adhesive solution (3) was prepared in the same manner as in Example 1 except that 100 parts by weight of the solution diluted to 20% by weight was 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 (3) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Example 4>
(Preparation of adhesive solution)
The acrylic pressure-sensitive adhesive solution (C) (40% by weight) was replaced with 100 parts by weight of the solution obtained by diluting the acrylic pressure-sensitive adhesive solution (A) (40% by weight) with ethyl acetate to 20% by weight. An acrylic pressure-sensitive adhesive solution (4) was prepared in the same manner as in Example 1 except that 100 parts by weight of the solution diluted to 20% by weight was 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 (4) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Example 5>
(Preparation of adhesive solution)
After adding 0.5 parts by weight of LiN (C ₂ F ₅ SO ₂ ) ₂ to 100 parts by weight of the acrylic polymer (D) solution and keeping it at around 25 ° C., the mixture is stirred for about 2 hours. As a polymerization initiator, 1.5 parts by weight of trimethylolpropane triacrylate and 0.1 part by weight of benzylmethyl ketal (manufactured by Ciba Specialty Chemicals, Irgacure 651) as a polymerization initiator are added and kept at around 25 ° C. for about 1 minute with stirring. And an acrylic pressure-sensitive adhesive solution (5) was prepared.

[Preparation of adhesive sheet]
The acrylic pressure-sensitive adhesive solution (5) was applied to one side of a polyethylene terephthalate film to form a pressure-sensitive adhesive layer having a thickness of 20 μm. Next, a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) having a silicone treatment on one side was bonded to the surface of the pressure-sensitive adhesive layer. This film sheet was irradiated with ultraviolet rays (illuminance 37 mW / cm ² , light amount 660 mJ / cm ² ) with a high-pressure mercury lamp (Ushio Electric Co., Ltd., UVL-4000-N) to produce an adhesive sheet.

<Comparative Example 1>
(Preparation of adhesive solution)
Example 1 except that 1.0 part by weight of the antistatic agent solution (c) (20% by weight) was used instead of 1.0 part by weight of the antistatic agent solution (a) (20% by weight). An acrylic pressure-sensitive adhesive solution (6) was prepared by the same method.

[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 2>
(Preparation of adhesive solution)
Example 2 was used except that 4.0 parts by weight of the antistatic agent solution (c) (50% by weight) was used instead of 4.0 parts by weight of the antistatic agent solution (b) (50% by weight). An acrylic pressure-sensitive adhesive solution (7) was prepared by the same method.

[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 3>
(Preparation of adhesive solution)
The acrylic polymer (E) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 1.0 part by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, TETRAD-C) as an agent, trimethylolpropane / tolylene diisocyanate trimer adduct (Nippon Polyurethane) Industrial Co., Ltd. (Coronate L) 0.27 parts by weight was added and kept at around 25 ° C., and mixed and stirred for about 1 minute to prepare an acrylic pressure-sensitive adhesive solution (8).

[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).

  According to the above method, the peeled voltage measurement and the corrosivity evaluation of the produced pressure-sensitive adhesive sheet were performed. The obtained results are shown in Table 1.

上記表１の結果より、本発明によって作製された粘着剤組成物を用いた場合（実施例１〜５）、全実施例において剥離帯電圧が抑制され、かつ、腐食の発生もないことがわかる。これに対して、リチウムイミド塩を用いていない比較例１および２のいずれにおいても、剥離帯電圧は低く抑えられているが、腐食の発生が認められた。また、酸価が２９より大きいアクリル系ポリマーからなる粘着剤組成物を用いた比較例３では、腐食の発生は見られなかったが、剥離帯電圧が高い結果となった。したがって、比較例ではいずれも、剥離帯電圧の抑制、ならびに腐食の発生の抑制を両立することができない結果となり、粘着シート用の粘着剤組成物には適さないことが明らかとなった。

From the results of Table 1 above, when the pressure-sensitive adhesive composition prepared according to the present invention is used (Examples 1 to 5), it is understood that the stripping voltage is suppressed and no corrosion occurs in all Examples. . In contrast, in both Comparative Examples 1 and 2 in which no lithium imide salt was used, the stripping voltage was kept low, but the occurrence of corrosion was observed. In Comparative Example 3 using the pressure-sensitive adhesive composition made of an acrylic polymer having an acid value greater than 29, no corrosion was observed, but the peel voltage was high. Therefore, in all of the comparative examples, it was impossible to achieve both suppression of the stripping voltage and suppression of the occurrence of corrosion, and it became clear that it was not suitable for the pressure-sensitive adhesive composition for pressure-sensitive adhesive sheets.

  Moreover, the adhesive sheet of Examples 1-5 of this invention has the adhesive force equivalent to the comparative examples 1 and 2 whose 180 degree peel adhesive force does not contain a fluorine-containing lithium imide salt, and is an adhesive for adhesive sheets. Suitable for agent compositions.

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

Claims (3)

  In the pressure-sensitive adhesive composition containing a (meth) acrylic polymer mainly composed of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the acid value of the (meth) acrylic polymer is 29 or less. A pressure-sensitive adhesive composition comprising a fluorine-containing lithium imide salt.   A pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition according to claim 1. A pressure-sensitive adhesive sheet obtained by forming a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition according to claim 1 on one side or both sides of a support film.

Images