JP2016121306A - Adhesive composition, adhesive sheet and optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition and an adhesive sheet, capable of suppressing deterioration of low-speed and high-speed peeling properties when peeling the adhesive sheet from an adherend, after adhering the adhesive sheet to the adhered; and preventing cissing and suppressing deterioration of a peeling force when an optical adhesive is separately adhered to the adherend after the adhesive sheet is peeled off from the adherend.SOLUTION: An adhesive composition includes: a (meth)acrylic polymer including, as a monomer component, 50-99.9 mass% (meth)acrylic monomer containing an alkyl group of C1 to 14 and a hydroxyl group-containing (meth)acrylic monomer; and an ether group-containing oligomer. The SP value of a monomer component composing the ether group-containing oligomer is larger than the SP value of the (meth)acrylic polymer. With regard to 100 pts. mass of the (meth)acrylic polymer, 0.2-10 pts. mass of the ether group-containing oligomer is included.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and an optical member. In particular, the pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition of the present invention protects the surface of an optical member such as a polarizing plate, a wavelength plate, a retardation plate, an optical compensation film, a reflection sheet, or a brightness enhancement film used in a liquid crystal display. It is useful as a surface protective film used for the purpose.

  Liquid crystal displays, plasma displays, OLED displays, and the like are laminated with optical films having various functions, such as optical polarizing plates, retardation plates, electromagnetic wave shielding films, antiglare films, and antireflection films. In order to prevent damage during the manufacturing process of the display and the performance inspection stage, these optical films are pasted together with a surface protective film. It is peeled off.

  Examples of the surface protective film for optical films include properties that require low contamination at the time of peeling, peeling antistatic property when peeling the surface protective film from the adherend, and high-speed peeling.

  Further, in order to develop the antistatic property of peeling on the adherend (for example, an optical film), a polyether-modified silicone (silicone component) or the like is contained as an antistatic agent in the pressure-sensitive adhesive layer constituting the surface protective film. In addition, an optical adhesive tape is applied on the same surface of the optical film (for example, a polarizing plate) after the silicone component is segregated on the surface of the adhesive (layer) and the surface protective film containing the silicone component is peeled off. Or when an interlayer filler is applied on the optical film, the silicone component remains on the optical film surface, the optical adhesive tape cannot be sufficiently adhered, and the light release progresses too much. When this is applied, repelling occurs and there is a problem of slipping at the interface (see Patent Documents 1 to 3).

JP2013-163745A JP 2013-244667 A JP 2013-245293 A

  Therefore, an object of the present invention is to mainly apply the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition to a pressure-sensitive adhesive sheet for protecting the surface of an optical member (optical film). After being attached to the adherend, low-speed and high-speed peelability when peeling the pressure-sensitive adhesive sheet from the adherend, and after peeling the pressure-sensitive adhesive sheet from the adherend, repelling the optical adhesive to the adherend separately An object of the present invention is to provide a pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive sheet (surface protective film) capable of preventing and suppressing a decrease in peeling force.

That is, the pressure-sensitive adhesive composition of the present invention has, as a monomer component, 50 to 99.9% by weight of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms and a hydroxyl group-containing (meth) acrylic. An adhesive composition containing a (meth) acrylic polymer containing a monomer and an ether group-containing oligomer, wherein the SP value of the monomer component constituting the ether group-containing oligomer is represented by the following formula (1) The SP value of the monomer component constituting the ether group-containing oligomer is greater than the SP value of the (meth) acrylic polymer, and is 100 parts by weight of the (meth) acrylic polymer. The ether group-containing oligomer is contained in an amount of 0.2 to 10 parts by mass.
SP = (δd ² + δp ² + δh ² ) ^0.5 (1)
(In the formula (1), δd, δp, and δh represent a dispersion term, a polar term, and a hydrogen bond term in the Hansen solubility parameter, respectively, and the unit is (MPa) ^1/2 .)

  In the pressure-sensitive adhesive composition of the present invention, the ether group-containing oligomer preferably has a weight average molecular weight of 800 to 6000.

  The pressure-sensitive adhesive composition of the present invention preferably contains an ionic compound.

  In the pressure-sensitive adhesive composition of the present invention, the ionic compound is preferably an alkali metal salt and / or an ionic liquid.

  In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition is preferably formed on at least one side of the support film.

The pressure-sensitive adhesive sheet of the present invention preferably has a measured peel force reduction rate of 40% or less based on the following formula (2).
Peeling force decrease rate (%) = (Peeling force (B) −Peeling force (A)) / Peeling force (B) (2)
(In the formula, peeling force (A) means that the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet is peeled off after being attached to the surface of the polarizing plate at 23 ° C. for 30 minutes, and then stretched polypropylene-based pressure-sensitive adhesive tape on the surface of the polarizing plate. Shows the peel force at a peeling speed of 0.3 m / min after sticking for 30 minutes at 23 ° C. The peel force (B) refers to the sticky surface of a stretched polypropylene-based pressure-sensitive adhesive tape without sticking the pressure-sensitive adhesive sheet. Is applied to the surface of the polarizing plate at 23 ° C. for 30 minutes, and the peeling force at a peeling speed of 0.3 m / min is shown.)

  In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer is preferably attached to the surface of the polarizing plate at 23 ° C. for 30 minutes, and then the peeling force at a peeling speed of 30 m / min is 2.5 N / 25 mm or less.

  The pressure-sensitive adhesive sheet of the present invention has a peeling voltage (absolute value) at a peeling speed of 10 m / min after sticking the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer to the surface of the polarizing plate at 23 ° C. × 50% RH for 24 hours. It is preferably 0 kV or less.

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

  The pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition of the present invention is a low-speed and high-speed peelability when peeling the pressure-sensitive adhesive sheet from the adherend after being attached to the adherend, and after peeling the pressure-sensitive adhesive sheet from the adherend, This is useful because it can prevent repellency when a separate optical adhesive is applied to the adherend, and can suppress a decrease in peel strength.

It is a schematic block diagram of the electric potential measurement part used for the measurement of peeling band voltage in an Example etc.

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

<(Meth) acrylic polymer>
The pressure-sensitive adhesive composition of the present invention comprises 50 to 99.9% by weight of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms and a hydroxyl group-containing (meth) acrylic monomer as a monomer component. (Meth) acrylic polymer containing In addition, 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.

  In addition, as a (meth) acrylic-type polymer used for this invention, if the (meth) acrylic-type polymer which contains the said (meth) acrylic-type monomer and has adhesiveness, it will not specifically limit.

  As the monomer component of the (meth) acrylic polymer of the present invention, (meth) acrylate ((meth) acrylic acid alkyl ester) having an alkyl group having 1 to 14 carbon atoms is used because excellent adhesiveness is obtained. Preferably, it is a (meth) acrylate having an alkyl group having 4 to 14 carbon atoms. In addition, for example, when an ionic compound or the like is used as the antistatic agent, it is a preferable aspect to use the monomer component also from the balance of compatibility with the ionic compound. As said (meth) acrylate, a seed | species or 2 or more types can be used in combination.

  The (meth) acrylic polymer contains, as a monomer component, 50 to 99.9% by mass of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, preferably 60 to 97% by mass. More preferably, it is 70-95 mass%. When the monomer component is within the above range, it is preferable from the viewpoint of obtaining appropriate wettability and cohesive force in the pressure-sensitive adhesive composition.

  In the present invention, specific examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms include, 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.

  Especially, when using the adhesive sheet of this invention as a surface protection film, 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 other (meth) acrylates having an alkyl group having 4 to 14 carbon atoms are preferred. It is done. By using a (meth) acrylate having an alkyl group having 4 to 14 carbon atoms, it becomes easy to control the peel strength (adhesive strength) to the adherend, and it becomes easy to obtain a product having excellent removability. .

  The pressure-sensitive adhesive composition of the present invention is characterized in that the (meth) acrylic polymer further contains a hydroxyl group-containing (meth) acrylic monomer as a monomer component. By using the hydroxyl group-containing (meth) acrylic monomer, it becomes easier to control the crosslinking of the pressure-sensitive adhesive composition, and as a result, balance between improvement of wettability by flow and reduction of peeling force (adhesive strength) in peeling. It becomes easier to control. Furthermore, unlike a (meth) acrylic monomer having a carboxyl group or a sulfonate group that can generally act as a crosslinking site, a hydroxyl group has an appropriate interaction with an ionic compound that can be used as an antistatic agent. It can be suitably used also in terms of antistatic properties.

  Examples of the hydroxyl group-containing (meth) acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide and the like.

  In the case of including the hydroxyl group-containing (meth) acrylic monomer, the hydroxyl group-containing (meth) acrylic monomer is 0.1% relative to 100% by mass of all the structural units (total monomer components) of the (meth) acrylic polymer. It is preferably 1 to 20% by mass, more preferably 0.5 to 15% by mass, and most preferably 1 to 10% by mass. Within the above range, it is easy to control the balance between wettability and cohesive force of the pressure-sensitive adhesive composition, which is preferable.

  In addition, as another polymerizable monomer component, the Tg is 0 ° C. or lower (usually −100 ° C. or higher) for the reason that it is easy to balance the adhesiveness. A polymerizable monomer or the like for adjusting the property can be used as long as the effects of the present invention are not impaired.

  In the (meth) acrylic polymer used in the present invention, examples of other polymerizable monomers other than the above monomers include sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, vinyl ester monomers, and aromatics. Components for improving cohesion and heat resistance such as vinyl monomers, carboxyl group-containing monomers, acid anhydride group-containing monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, N-acryloylmorpholine, A component having a functional group that functions as a crosslinking base point or an improvement in peel strength (adhesive strength) such as a vinyl ether monomer can be appropriately used. These monomers can be used alone or in combination of two or more.

  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 ) Acrylyloxynaphthalene sulfonic acid, sodium vinyl sulfonate and the like.

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

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and 2- (meth) acrylic acid. Leuoxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypolycaprolactone mono (meta ) Acrylate, 2- (meth) acryloyloxyethyl tetrahydrophthalic acid 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 cyano group-containing monomer include acrylonitrile and methacrylonitrile.

  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 other substituted styrene.

  Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethyl. Examples include methacrylamide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, diacetone acrylamide, and the like.

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

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

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

  In the present invention, the other polymerizable monomers may be used alone or in admixture of two or more, but the above (meth) acrylic polymer all structural units (all monomer components) It is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, and particularly preferably 0 to 10% by mass with respect to 100% by mass. By using the other polymerizable monomer within the above range, good removability can be appropriately adjusted. When an ionic compound or the like is used as an antistatic agent, an ionic compound is used. A good interaction with the like can be achieved.

  In addition, the (meth) acrylic polymer may contain a polyfunctional monomer as a monomer component as necessary in order to adjust the cohesive force of the pressure-sensitive adhesive layer.

  Examples of the polyfunctional monomer include (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, penta Erythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) Acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate Polyester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di (meth) acrylate. Among these, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. A polyfunctional (meth) acrylate can be used 1 type or in combination of 2 or more types.

  The content of the polyfunctional monomer varies depending on the molecular weight, the number of functional groups, and the like, but is 0 to 3% by mass with respect to 100% by mass of the total amount of monomer components for preparing the (meth) acrylic polymer, preferably It is 0-2 mass%, More preferably, it can add so that it may become 0-1 mass%. When the content of the polyfunctional monomer exceeds 3% by mass, the cohesive force of the pressure-sensitive adhesive layer may become too high, and the peeling force (adhesive force) may decrease.

  The polymerization method of the (meth) acrylic polymer used in the present invention is not particularly limited, and (meth) acrylic such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and radiation curing (radiation energy) polymerization. Various commonly used polymerization methods can be applied as a polymer synthesis method, but in particular, from the viewpoint of workability and the characteristics such as low contamination on the adherend, solution polymerization is more preferable. It is. Further, the polymer obtained may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, and the like.

<Polymerization initiator>
In the preparation of the (meth) acrylic polymer, when the monomer component is polymerized by radiation energy (for example, irradiation with heat or ultraviolet rays), a thermal polymerization initiator or a photopolymerization initiator (photoinitiation) (Meth) acrylic polymer can be easily synthesized using a polymerization initiator such as (agent). The said polymerization initiator can be used 1 type or in combination of 2 or more types.

  Examples of the thermal polymerization initiator include azo polymerization initiators (for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis). (2-methylpropionic acid) dimethyl, 4,4′-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [ 2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-di) Methyleneisobutylamidine) dihydrochloride, etc.); peroxide polymerization initiators (for example, dibenzoyl peroxide, t-butylpermaleate, lauro peroxide) Le etc.); redox polymerization initiators, and the like.

  Although it does not restrict | limit especially as content of the said thermal-polymerization initiator, For example, 0.01-5 mass parts is preferable with respect to 100 mass parts of monomer components whole quantity which prepares the said (meth) acrylic-type polymer, More preferably Is 0.05 to 3 parts by mass. When the content is less than 0.01 parts by mass, the polymerization reaction may become insufficient. Moreover, when the said content exceeds 5 mass parts, the molecular weight of a polymer may become small too much. And thereby, the cohesion force of the adhesive layer formed becomes low, and adhesive characteristics, such as holding | maintenance property and repulsion resistance, may fall.

  The photopolymerization initiator is not particularly limited. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photo Active oxime photopolymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, acylphosphine oxide photopolymerization initiator An initiator or the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- 1-one [trade name: Irgacure 651, manufactured by BASF Corporation], anisole methyl ether and the like can be mentioned. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone [trade name: Irgacure 184, manufactured by BASF Corp.], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- ( 2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one [trade name: Irgacure 2959, manufactured by BASF Corp.], 2-hydroxy-2-methyl-1-phenyl-propane- 1-one [trade name: Darocur 1173, manufactured by BASF Corporation], methoxyacetophenone, and the like can be given. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropane-1- ON etc. are mentioned. Examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalene sulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime.

  The benzoin photopolymerization initiator includes, for example, benzoin. Examples of the benzyl photopolymerization initiator include benzyl and the like. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like are included.

  Examples of the acylphosphine photopolymerization initiator include bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis ( 2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, bis (2,6-dimethoxybenzoyl) octylphosphine Oxide, bis (2- Toxibenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2-methoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (2-methyl Propan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropane-1- Yl) phosphine oxide, bis (2,4-dimethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide Bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis 2,6-dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2,6 -Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide Bis (2,4,6-trimethylbenzoyl) -2,5-diisopropylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2-methylphenylphosphine oxide, bis (2 4,6-trimethylbenzoyl) -4-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2, 3,5,6-tetramethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide, 2,6-dimethoxybenzoyl-2,4,6-trimethyl Benzoyl-n-butylphosphine oxide, bis (2,4,4 -Trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2,4,6-trimethylbenzoyl) phosphine oxide] Examples include decane and tri (2-methylbenzoyl) phosphine oxide.

  Although content in particular of the said photoinitiator is not restrict | limited, For example, 0.01-5 mass parts is preferable with respect to 100 mass parts of monomer components whole quantity which prepares the said (meth) acrylic-type polymer, More preferably It is 0.05-3 mass parts. When the content is less than 0.01 parts by mass, the polymerization reaction may become insufficient. Moreover, when the said content exceeds 5 mass parts, the molecular weight of the polymer obtained may become too small. And thereby, the cohesion force of the adhesive layer formed becomes low, and adhesive characteristics, such as holding | maintenance property and repulsion resistance, may fall.

  Examples of the radiation include ultraviolet (UV), laser beam, α-ray, β-ray, γ-ray, X-ray, and electron beam. Ultraviolet rays are preferable from the viewpoints of controllability, ease of handling, and cost. Used for. 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.

  Furthermore, it is also possible to use a photopolymerization initiation assistant such as amines together with the photopolymerization initiator. Examples of the photopolymerization initiation assistant 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. The photopolymerization initiation assistant is preferably added in an amount of 0.05 to 10 parts by weight, more preferably 0.1 to 7 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. . Within the above range, it is preferable from the viewpoint of easily controlling the polymerization reaction and obtaining an appropriate molecular weight.

In addition, when the photopolymerization initiator is blended, the pressure-sensitive adhesive composition is directly applied on an adherend (protected body) or after being applied to a predetermined coated body such as a separator. Alternatively, the adhesive layer can be obtained by light irradiation after coating on one side of the support film (base material). 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 200 to 4000 mJ / cm ² .

  The (meth) acrylic polymer used in the present invention preferably has a weight average molecular weight (Mw) of 100,000 to 5,000,000, more preferably 200,000 to 4,000,000, still more preferably 300,000 to 3,000,000. When the weight average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer tends to be small, so that adhesive residue tends to be generated when the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) is peeled off. On the other hand, when the weight average molecular weight exceeds 5 million, the fluidity of the polymer is lowered, and the wettability of the pressure-sensitive adhesive composition (pressure-sensitive adhesive composition solution) to the adherend (for example, a polarizing plate) becomes insufficient, There is a tendency to cause blisters generated between the adherend and the pressure-sensitive adhesive composition layer (pressure-sensitive adhesive layer). In addition, a weight average molecular weight means what was obtained by measuring by gel permeation chromatography (GPC).

  The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower, still more preferably −41 ° C. or lower, particularly preferably −51 ° C. or lower, most preferably. It is −61 ° C. or lower (usually −100 ° C. or higher). When the glass transition temperature is higher than 0 ° C., the polymer is difficult to flow, for example, the wettability to the adherend becomes insufficient, and the cause of the swelling generated between the adherend and the pressure-sensitive adhesive composition layer of the pressure-sensitive adhesive sheet Tend to be. In particular, by setting the glass transition temperature to −61 ° C. or lower, it becomes easy to obtain a pressure-sensitive adhesive composition excellent in wettability to the adherend and light peelability. In addition, the glass transition temperature of the said (meth) acrylic-type polymer can be adjusted in the said range by changing suitably the monomer component and composition ratio to be used.

[Ether group-containing oligomer]
The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition containing an ether group-containing oligomer, and the SP value of the monomer component constituting the ether group-containing oligomer is represented by the following formula (1). The SP value of the monomer component constituting the ether group-containing oligomer is larger than the SP value of the (meth) acrylic polymer, and the ether group is contained in 100 parts by mass of the (meth) acrylic polymer. 0.2-10 mass parts of containing oligomers are contained, It is characterized by the above-mentioned.
SP = (δd ² + δp ² + δh ² ) ^0.5 (1)
(In the formula (1), δd, δp, and δh represent a dispersion term, a polar term, and a hydrogen bond term in the Hansen solubility parameter, respectively, and the unit is (MPa) ^1/2 .)
In the present invention, the SP value of the monomer component constituting the ether group-containing oligomer (hereinafter sometimes referred to as “oligomer”) is the above (meth) acrylic polymer (hereinafter referred to as “polymer” or “adhesive polymer”). The reason is not clear by showing a value larger than the SP value of)), but if any oligomer or polymer is selected, the speed at which the pressure-sensitive adhesive sheet is peeled off from the adherend In addition, it has good high-speed peelability (light peelability) and suppresses repellency when an optical adhesive (tape, sheet, etc.) is separately applied to the adherend after peeling the adhesive sheet from the adherend. In addition, it is useful to know whether or not an adhesive sheet (surface protective film) that can suppress a decrease in peel strength (prevention of a decrease in peel strength) can be obtained. In the present invention, when there are a plurality of monomer components constituting the oligomer, any one of them does not include a monomer component (constituting the oligomer) smaller than the SP value of the polymer. That is, it means that all monomer components are larger than the SP value of the polymer.

  Further, when the SP value (all) of the monomer components constituting the oligomer is larger than the SP value of the polymer, the oligomer is present in the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer surface is bonded to the separator. When the pressure-sensitive adhesive layer surface is bonded to the adherend, the oligomer will be concentrated at the interface between the adherend and the pressure-sensitive adhesive layer, and when peeling the pressure-sensitive adhesive layer surface from the adherend, It can be presumed that light peelability and antistatic properties can be exhibited. Further, after the surface of the pressure-sensitive adhesive layer is peeled off from the adherend, the oligomer having a high SP value remains on the adherend surface, but the SP value is large and the interaction with the adherend is large. Then, even when the surface of the pressure-sensitive adhesive layer is bonded to another adherend, the peeling force based on the pressure-sensitive adhesive layer does not decrease, and adhesion reliability can be maintained. Moreover, since the remaining oligomer is a trace amount, even if it confirms visually, an oligomer cannot be confirmed. Therefore, contamination of the adherend does not occur. According to the present invention, these characteristics can be predicted and useful by simply calculating the SP values of the polymer and the monomer component constituting the oligomer.

  In addition, when SP value of the monomer component which comprises the said oligomer (one kind of monomer when using several types of monomers) is smaller than the said polymer, an adhesive layer and the surface of the said adhesive layer Since the oligomer is concentrated at the interface with the separator (PET or the like) attached to the adhesive, the separator attached to the surface of the adhesive layer is peeled off from the surface of the adhesive layer, and the adhesive is applied to the adherend. When the layer surfaces are bonded together and then further peeled, the contained oligomer remains on the adherend surface. Since the SP value of the monomer component constituting the oligomer is smaller than the SP value of the polymer, the polarity of the adherend surface will be lowered, and it will be peeled off when an optical adhesive (tape, sheet, etc.) is applied separately. When the force is reduced or when an interlayer filler is applied, a repellency phenomenon in which the interlayer filler cannot be applied uniformly occurs, which is inferior in adhesion reliability and is not preferable.

  When the SP value of the monomer component constituting the oligomer has an SP value equivalent to that of the polymer, the oligomer is present even when the pressure-sensitive adhesive layer surface is bonded to the separator or when the pressure-sensitive adhesive layer surface is bonded to the adherend. Segregation (movement) to the adherend surface or separator surface does not occur, and the light peelability and antistatic property when peeling the pressure-sensitive adhesive layer surface from the adherend cannot be exhibited.

The SP value in the present invention means a Hansen solubility parameter. The Hansen solubility parameter is a three-dimensional space obtained by dividing the solubility parameter introduced by Hildebrand into three components: a dispersion term δd, a polar term δp, and a hydrogen bond term δh. The dispersion term δd indicates the effect due to the dispersion force, the polar term δp indicates the effect due to the dipole force, and the hydrogen bond term δh indicates the effect due to the hydrogen bond force.
The definition and calculation of Hansen solubility parameters are described in Charles M. et al. It can be carried out by the method described in Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007).
In addition, by using computer software Hansen Solubility Parameters in Practice (HSPIP), Hansen solubility parameters can be easily estimated from the chemical structure of a medium whose literature values are not known.
In the present invention, the medium to be used is selected by using the value for the medium registered in the database using the HSPiP version 4.1 and the estimated value for the medium not registered. It is.
In general, the SP value is used as an indicator of polymer miscibility. The closer the SP value of the oligomer and the polymer to be used ((meth) acrylic polymer) is, the easier it is to mix the polymer.

  Further, the oligomer has an ether group, so that it is concentrated on the interface between the adherend (for example, an optical film) and the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) together with an antistatic agent such as an ionic compound. Can do. In addition, the antistatic agent is concentrated at the interface, so that the antistatic agent is transferred to the surface of the optical film in a small amount (residual) at the time of peeling, and no static electricity is generated when the pressure sensitive adhesive sheet is peeled off. It becomes. Examples of the ether group (oxyalkylene group) include an oxymethylene group, an oxyethylene group, and an oxypropylene group.

  The weight average molecular weight (Mw) of the oligomer is preferably 800 to 6000, more preferably 900 to 4000, and still more preferably 1000 to 3000. When the molecular weight is within the above range, the concentration rate of the oligomer is increased, and it takes a short time until the light releasability and the function of suppressing repelling after peeling are realized. In addition, a weight average molecular weight means what was obtained by measuring by gel permeation chromatography (GPC).

  The oligomer is a polymer having a weight average molecular weight (Mw) smaller than that of the (meth) acrylic polymer, has higher molecular mobility than the (meth) acrylic polymer, and has an optical film and an adhesive layer. It becomes a preferable aspect at the point which is easy to concentrate on the adhesion (adhesion) interface.

  Examples of the oligomer include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and one or both ends thereof are alkyl groups such as a methyl group, alkenyl groups such as an allyl group, aryl groups such as a phenyl group, acetyl And a compound in which an acyl group such as a group or a (meth) acryloyl group, or a combination thereof is bonded to the end of a molecular chain.

  In addition, the oligomer is, for example, the same as the (meth) acrylic polymer described above, and various types of commonly used synthesis methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and radiation curing polymerization. Polymerization methods can be applied.

  In order to adjust the weight average molecular weight (Mw) of the oligomer, a chain transfer agent can be used during the polymerization. Examples of chain transfer agents used include compounds having a mercapto group such as octyl mercaptan, t-nonyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, α-thioglycerol; thioglycolic acid, methyl thioglycolate, Ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene Examples include glycol thioglycolate, neopentyl glycol thioglycolate, and pentaerythritol thioglycolate. Particularly preferred chain transfer agents include α-thioglycerol, mercaptoethanol, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, Examples include octyl thioglycolate and isooctyl thioglycolate. In addition, a chain transfer agent can be used 1 type or in combination of 2 or more types.

  Although it does not restrict | limit especially as content of the said chain transfer agent, Usually, 0.1-20 mass parts of chain transfer agents are preferable with respect to 100 mass parts of monomer units whole quantity which comprises the said oligomer, 0.2. -15 mass parts is more preferable, More preferably, it is 0.3-10 mass parts. By adjusting the content of the chain transfer agent within the above range, an oligomer having a suitable molecular weight can be obtained.

  Moreover, content of the said oligomer is 0.2-10 mass parts with respect to 100 mass parts of said (meth) acrylic-type polymers, Preferably it is 0.3-8 mass parts, More preferably, it is 0.00. 4 to 6 parts by mass. When the oligomer content exceeds 10 parts by mass, the resulting adhesive layer has a high modulus of elasticity, resulting in poor adhesive properties at low temperatures and a sufficient peel (adhesive) force even at room temperature. It may disappear, which is not preferable. Moreover, when content of the said oligomer is less than 0.2 mass part, the effect which improves the holding | maintenance (cohesion force) and repulsion resistance of an adhesive layer may not be acquired.

<Ionic compounds>
In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive composition preferably contains an ionic compound as an antistatic agent, and the ionic compound is more preferably an alkali metal salt and / or an ionic liquid. preferable. By containing these ionic compounds as an antistatic agent, excellent antistatic properties can be imparted.

<Alkali metal salt>
Since the alkali metal salt has high ion dissociation properties, it is preferable in that it exhibits excellent antistatic properties even with a small amount of addition. Examples of the alkali metal salt include a cation composed of Li ⁺ , Na ⁺ , K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN. _{^{-, ClO 4 -, NO 3}} -, CH 3 COO -, C 9 H 19 COO -, CF 3 COO -, C 3 F 7 COO -, CH 3 SO 3 -, CF 3 SO 3 -, C 4 F 9 SO ₃ ⁻ , C ₂ H ₅ OSO ₃ ⁻ , C ₆ H ₁₃ OSO ₃ ⁻ , C ₈ H ₁₇ OSO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , ^{_{F (HF) n -, (}} CN) _{^{N -, (CF 3 SO 2}} ) (CF 3 CO) N -, (CH 3) 2 PO 4 -, (C 2 H 5) 2 PO 4 -, CH 3 (OC 2 H 4) 2 OSO 3 -, Metal salt composed of an anion consisting of C ₆ H ₄ (CH ₃ ) SO ₃ ⁻ , (C ₂ F ₅ ) ₃ PF ₃ ⁻ , CH ₃ CH (OH) COO ⁻ , and (FSO ₂ ) ₂ N ^−. Are preferably used. In particular, 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 ( Lithium salts such as FSO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C, and more preferably LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) Lithium salt of ₂ N, Li (C ₃ F ₇ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO ₂ ) ₂ N, Li (FSO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C. These alkali metal salts may be used alone or in combination of two or more.

<Ionic liquid>
The ionic liquid refers to a liquid (liquid) in a range of 0 to 150 ° C. and a non-volatile molten salt. Since the ionic liquid is liquid in any of the above ranges, it can be easily added and dispersed or dissolved in the pressure-sensitive adhesive as compared with a solid salt. Furthermore, since the ionic liquid has no vapor pressure (non-volatile), it does not disappear with time, and the antistatic property can be continuously obtained.

  Further, by using the ionic liquid as an antistatic agent, a pressure-sensitive adhesive layer having a high antistatic effect can be obtained without impairing the adhesive properties (adhesiveness, removability, etc.). Although details of the reason why excellent antistatic properties can be obtained by using ionic liquids are not clear, ionic liquids have a low melting point (melting point of 150 ° C. or lower) compared to ordinary ionic compounds, so molecular movement is easy. It is considered that excellent antistatic ability can be obtained. In particular, when antistatic is applied to the adherend, it is considered that an excellent peeling antistatic property on the adherend can be achieved by transferring a very small amount of the ionic liquid to the adherend. In particular, since an ionic liquid having a melting point of room temperature (25 ° C.) or less can be transferred to an adherend more efficiently, excellent antistatic properties can be obtained.

  The ionic liquid is preferably a nitrogen-containing onium salt, a sulfur-containing onium salt, or a phosphorus-containing onium salt, and more preferably an organic cation component represented by the following general formulas (C1) to (C5) And those consisting of an anionic component are preferably used. With these cation liquids having cations, those having further excellent antistatic properties can be obtained.

R _a in the formula (C1) represents a hydrocarbon group having 4 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, and R _b and R _c May be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. However, when the nitrogen atom contains a double bond, there is no R _c .

R _d in the formula (C2) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, and R _e , R _f And R _g may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom.

R _h in the formula (C3) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom, R _i , R _j , And R _k may be the same or different and each represents hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom.

Z in the formula (C4) represents a nitrogen, sulfur, or phosphorus atom, and R ₁ , R _m , R _n , and R _o are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms. In addition, a functional group in which a part of the hydrocarbon group is substituted with a hetero atom may be used. However, when Z is a sulfur atom, there is no _Ro .

R _P of the formula (C5) represents a hydrocarbon group having 1 to 18 carbon atoms, a part of the hydrocarbon group may be substituted by a functional group with a heteroatom.

  Examples of the cation represented by the formula (C1) include a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a cation having a pyrroline skeleton, a cation having a pyrrole skeleton, and a morpholinium cation.

  Examples of the cation represented by the formula (C2) include an imidazolium cation, a tetrahydropyrimidinium cation, and a dihydropyrimidinium cation.

  Examples of the cation represented by the formula (C3) include a pyrazolium cation and a pyrazolinium cation.

  Examples of the cation represented by the formula (C4) include a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraalkylphosphonium cation, and a part of the alkyl group is substituted with an alkenyl group, an alkoxyl group, or an epoxy group. And so on.

Examples of the cation represented by the formula (C5) include a sulfonium cation. Further, the formula Specific examples of R _P in (E) is a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, An octadecyl group etc. are mentioned.

On the other hand, the anion component is not particularly limited as long as it satisfies that it becomes an ionic liquid. For example, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF _{^{6 -, SCN -, ClO 4}} -, NO 3 -, CH 3 COO -, CF 3 COO -, CH 3 SO 3 -, CF 3 SO 3 -, C 4 F 9 SO 3 -, (CF 3 SO 2) _{^{2 N -, (C 2 F}} 5 SO 2) 2 N -, (C 3 F 7 SO 2) 2 N -, (C 4 F 9 SO 2) 2 N -, (CF 3 SO 2) 3 C -, AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) _n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , _{^{C 3 F 7 COO -, (}} CF 3 SO 2) (CF _{^{3 CO) N -, C 9}} H 19 COO -, (CH 3) 2 PO 4 -, (C 2 H 5) 2 PO 4 -, CH 3 OSO 3 -, C 2 H 5 OSO 3 -, C 4 H ₉ OSO ₃ ⁻ , C ₆ H ₁₃ OSO ₃ ⁻ , C ₈ H ₁₇ OSO ₃ ⁻ , CH ₃ (OC ₂ H ₄ ) ₂ OSO ₃ ⁻ , C ₆ H ₄ (CH ₃ ) SO ₃ ⁻ , (C ₂ F ₅ ) ₃ PF ₃ ⁻ , CH ₃ CH (OH) COO ⁻ , (FSO ₂ ) ₂ N ⁻ , B (CN) ₄ ⁻ , C (CN) ₃ ⁻ , N (CN) ₂ ⁻ , p-toluenesulfonate anion 2- (2-methoxyethyl) ethyl sulfate anion or the like can be used.

  Moreover, as an anion component, the anion etc. which are represented by a following formula (C6) can also be used.

［式（Ｃ６）中のＲ_１〜Ｒ_４は、それぞれ独立に、水素原子、置換基を有してもよいアルキル基、置換基を有してもよいアルケニル基、置換基を有してもよいアルキニル基、置換基を有してもよいアリール基、及び、置換基を有してもよい複素環基を表わす。前記置換基の水素原子は、更に他の置換基（電子吸引性基の置換基等）に置換されていても構わない。]

[R _{1 to} R ₄ in Formula (C6) may each independently have a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group that may have a substituent, or a substituent. A good alkynyl group, an aryl group which may have a substituent, and a heterocyclic group which may have a substituent are represented. The hydrogen atom of the substituent may be further substituted with another substituent (such as a substituent of an electron-withdrawing group). ]

Moreover, as an anion component, the anion etc. which are represented with a following formula (C7) can also be used.

  As the anion component, in particular, an anion component containing a fluorine atom is preferably used because an ionic liquid having a low melting point is obtained or an ionic liquid excellent in compatibility with a (meth) acrylic polymer is obtained. .

  A commercially available ionic liquid may be used, but it can also be synthesized as follows. The method of synthesizing the ionic liquid is not particularly limited as long as the target ionic liquid can be obtained. In general, however, it is described in the document “Ionic liquids—the forefront and future of development” [issued by CMC Publishing Co., Ltd.]. As described, a halide method, a hydroxide method, an acid ester method, a complex formation method, a neutralization method, and the like are used.

  The synthesis method of the halide method, hydroxide method, acid ester method, complex formation method, and neutralization method will be described below using a nitrogen-containing onium salt as an example. Other sulfur-containing onium salts, phosphorus-containing onium salts, etc. This ionic liquid can also be obtained by the same method.

The halide method is a method carried out by reactions as shown in the following formulas (1) to (3). First, a tertiary amine and an alkyl halide are reacted to obtain a halide. (Reaction formula (1), chlorine, bromine and iodine are used as the halogen) Acid (HA) or salt (MA, M having the anionic structure (A ⁻ ) of the ionic liquid intended for the obtained halide A target ionic liquid (R ₄ NA) is obtained by reacting with a target anion such as ammonium, lithium, sodium, potassium and the like to form a salt.

The hydroxide method is a method performed by reactions as shown in (4) to (8). First, halide (R ₄ NX) is subjected to ion exchange membrane electrolysis (reaction formula (4)), OH type ion exchange resin method (reaction formula (5)) or reaction with silver oxide (Ag ₂ O) (reaction formula ( 6)) to obtain the hydroxide (R ₄ NOH). (Chlorine, bromine and iodine are used as the halogen) The obtained hydroxide is subjected to the reaction of the reaction formulas (7) to (8) in the same manner as the halogenation method, and the target ionic liquid (R ₄ NA ) Is obtained.

The acid ester method is a method performed by reactions as shown in (9) to (11). First, a tertiary amine (R ₃ N) is reacted with an acid ester to obtain an acid ester product. (Reaction formula (9), as the acid ester, an ester of an inorganic acid such as sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid or carbonic acid, or an organic acid such as methanesulfonic acid, methylphosphonic acid or formic acid) The target ionic liquid (R ₄ NA) is obtained from the obtained acid ester using the reactions of the reaction formulas (10) to (11) in the same manner as in the halogenation method. Further, by using methyl trifluoromethanesulfonate, methyl trifluoroacetate or the like as the acid ester, an ionic liquid can be obtained directly.

The complex formation method is a method performed by reactions as shown in (12) to (15). First, a quaternary ammonium halide (R ₄ NX), a quaternary ammonium hydroxide (R ₄ NOH), a quaternary ammonium carbonate ester (R ₄ NOCO ₂ CH ₃ ) or the like is added to hydrogen fluoride (HF) or Reaction with ammonium fluoride (NH ₄ F) gives a quaternary ammonium fluoride salt. (Reaction formulas (12) to (14)) The obtained quaternary ammonium fluoride salt is complexed with a fluoride such as BF ₃ , AlF ₃ , PF ₅ , AsF ₅ , SbF ₅ , NbF ₅ , TaF _5. An ionic liquid can be obtained. (Reaction Formula (15))

The neutralization method is a method performed by a reaction as shown in (16). Tertiary amine and HBF ₄ , HPF ₆ , CH ₃ COOH, CF ₃ COOH, CF ₃ SO ₃ H, (CF ₃ SO ₂ ) ₂ NH, (CF ₃ SO ₂ ) ₃ CH, (C ₂ F ₅ SO ₂ ) ₂ It can be obtained by reacting with an organic acid such as NH.

  R in the formulas (1) to (16) represents hydrogen or a hydrocarbon group having 1 to 20 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. Good.

  In addition, the said ionic liquid may be used independently and may mix and use 2 or more types.

  In the pressure-sensitive adhesive composition of the present invention, the content of the ionic compound is preferably 0.001 to 5 parts by mass, more preferably 0.005 to 100 parts by mass of the (meth) acrylic polymer. 3 parts by mass, more preferably 0.01-1 part by mass, and most preferably 0.02-0.5 part by mass. Within the above range, the resulting pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) is preferable because it is easy to achieve both antistatic properties and low contamination.

<Crosslinking agent>
In order to adjust the cohesive strength of the pressure-sensitive adhesive layer obtained in the present invention, the pressure-sensitive adhesive composition may contain a crosslinking agent. As the cross-linking agent, a cross-linking agent generally used in the pressure-sensitive adhesive field can be used. For example, an isocyanate compound, an epoxy compound, a silicone compound, an oxazoline compound, an aziridine compound, a silane compound, and a melamine compound (Alkyl etherified melamine compounds, etc.), metal chelate compounds and the like. In particular, isocyanate compounds, epoxy compounds, and metal chelate compounds can be preferably used. These compounds may be used alone or in combination of two or more.

  Examples of the isocyanate compounds include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, 2,4 -Aromatic isocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 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.), Isocyanate of hexamethylene diisocyanate Rate body (trade name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) and isocyanate adducts and the like. Alternatively, a compound having at least one isocyanate group and one or more unsaturated bonds in one molecule, specifically, 2-isocyanatoethyl (meth) acrylate may be used as the isocyanate compound. it can.

  Examples of the epoxy compound include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylol. Propane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylenediamine (trade name TETRAD-X, manufactured by Mitsubishi Gas Chemical Company) and 1,3-bis ( N, N-diglycidylaminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.).

  Examples of the melamine compound include hexamethylol melamine. Moreover, as said aziridine type compound (aziridine derivative), for example, the trade name HDU (manufactured by Mutual Pharmaceutical Co., Ltd.), the trade name TAZM (manufactured by Mutual Pharmaceutical Co., Ltd.), the trade name TAZO (manufactured by Mutual Pharmaceutical Co., Ltd.) ) Etc.

  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.

  It is preferable that 0.1-15 mass parts of content of the crosslinking agent used for this invention is contained with respect to 100 mass parts of said (meth) acrylic-type polymers, More preferably, it is 0.5-10 masses. Part, more preferably 1 to 8 parts by weight. When the content is less than 0.1 parts by mass, the crosslinking formation by the crosslinking agent becomes insufficient, the cohesive force of the pressure-sensitive adhesive layer 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 mass, the cohesive force of the pressure-sensitive adhesive layer is large, the fluidity is lowered, and the wettability to the adherend becomes insufficient, and the adherend and the surface protective film (adhesive sheet). There is a tendency to cause blisters generated between the adhesive layer (adhesive composition layer).

  The pressure-sensitive adhesive composition used in the present invention may further contain a crosslinking accelerator. The kind of crosslinking accelerator can be suitably selected according to the kind of crosslinking agent to be used. In the present specification, the crosslinking accelerator refers to a catalyst that increases the speed of the crosslinking reaction by the crosslinking agent. Examples of the crosslinking accelerator include tin (Sn) -containing compounds such as dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate, tetra-n-butyltin, and trimethyltin hydroxide; N, N, N ′, N′-tetramethylhexanediamine, amines such as triethylamine, nitrogen (N) -containing compounds such as imidazoles; tris (acetylacetonato) iron, tris (hexane-2,4-dionato) iron, Tris (heptane-2,4-dionato) iron, Tris (heptane-3,5-dionato) iron, Tris (5-methylhexane-2,4-dionato) iron, Tris (octane-2,4-dionato) iron , Tris (6-methylheptane-2,4-dionato) iron, tris (2,6-dimethylheptane-3,5- Onato) iron, tris (nonane-2,4-dionato) iron, tris (nonane-4,6-dionato) iron, tris (2,2,6,6-tetramethylheptane-3,5-dionato) iron, Tris (tridecane-6,8-dionato) iron, tris (1-phenylbutane-1,3-dionato) iron, tris (hexafluoroacetylacetonato) iron, tris (ethyl acetoacetate) iron, tris (acetoacetate- n-propyl) iron, tris (isopropyl acetoacetate) iron, tris (acetoacetate-n-butyl) iron, tris (acetoacetate-sec-butyl) iron, tris (acetoacetate-tert-butyl) iron, tris (propionyl) Methyl acetate) iron, tris (propionyl ethyl acetate) iron, tris (propionyl acetate-n-propyl) iron, tris (propionyl acetate isopropyl) iron, Lis (propionyl acetate-n-butyl) iron, Tris (propionyl acetate-sec-butyl) iron, Tris (propionyl acetate-tert-butyl) iron, Tris (benzyl acetoacetate) iron, Tris (dimethyl malonate) iron, Tris Illustrative are iron-containing compounds such as (diethyl malonate) iron, trimethoxyiron, triethoxyiron, triisopropoxyiron, ferric chloride. These crosslinking accelerators may be used alone or in combination of two or more. Of these, tin (Sn) -containing compounds are preferred. The amount of the crosslinking accelerator contained in the pressure-sensitive adhesive composition is, for example, about 0.0001 to 1.0 part by mass, preferably 0.001 to 0.5 part by mass with respect to 100 parts by mass of the (meth) acrylic polymer. About a part can be blended.

  Furthermore, the pressure-sensitive adhesive composition may contain a compound that causes keto-enol tautomerism. For example, in a pressure-sensitive adhesive composition containing a cross-linking agent or a pressure-sensitive adhesive composition that can be used by blending a cross-linking agent, an embodiment including a compound that produces the keto-enol tautomerism can be preferably employed. Thereby, the excessive viscosity raise and gelation of an adhesive composition after a crosslinking agent mixing | blending can be suppressed, and the effect of extending the pot life of an adhesive composition may be implement | achieved. When at least an isocyanate compound is used as the crosslinking agent, it is particularly meaningful to contain a compound that causes keto-enol tautomerism. This technique can be preferably applied when, for example, the pressure-sensitive adhesive composition is in an organic solvent solution or a solvent-free form.

  Various β-dicarbonyl compounds can be used as the compound that causes keto-enol tautomerism. Specific examples include acetylacetone, 2,4-hexanedione, 3,5-heptanedione, 2-methylhexane-3,5-dione, 6-methylheptane-2,4-dione, 2,6-dimethylheptane- Β-diketones such as 3,5-dione; acetoacetates such as methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, tert-butyl acetoacetate; ethyl propionyl acetate, ethyl propionyl acetate, isopropyl propionyl acetate, propionyl acetate propionyl acetates such as tert-butyl; isobutyryl acetates such as ethyl isobutyryl acetate, ethyl isobutyryl acetate, isopropyl isobutyryl acetate, tert-butyl isobutylyl acetate; malonates such as methyl malonate and ethyl malonate; etc. And the like. Among these, acetylacetone and acetoacetic acid esters are preferable compounds. Such compounds that produce keto-enol tautomerism may be used alone or in combinations of two or more.

  Content of the compound which produces the keto-enol tautomerism can be 0.1-20 mass parts with respect to 100 mass parts of said (meth) acrylic-type polymers, and usually 0.5-15. It is appropriate to set it as a mass part (for example, 1-10 mass parts). If the amount of the compound is too small, it may be difficult to achieve a sufficient use effect. On the other hand, if the compound is used more than necessary, it may remain in the pressure-sensitive adhesive layer and reduce the cohesive force.

  Furthermore, the pressure-sensitive adhesive composition of the present invention may contain other known additives as long as the effects of the present invention are not impaired. For example, powders such as colorants and pigments, plastics, etc. Agent, tackifier, surfactant, emulsifier, dispersant, low molecular weight polymer, surface lubricant, leveling agent, antioxidant, corrosion inhibitor, light stabilizer, UV absorber, polymerization inhibitor, silane coupling An agent, an inorganic or organic filler, a metal powder, a particulate shape, a foil-like material, and the like can be appropriately added depending on the use.

<Adhesive layer / adhesive sheet>
In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition (cross-linking the pressure-sensitive adhesive composition) is preferably formed on at least one side of the support film. According to the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive sheet is provided with a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition having the above-described effects, so that the pressure-sensitive adhesive sheet with reduced contamination to the adherend (protected body) is obtained. . In addition, when an antistatic agent or the like is used, it is possible to prevent an electrostatic charge on an uncharged adherend when it is peeled off. For this reason, charging and contamination are particularly serious problems related to optical and electronic components. It becomes very useful as an antistatic adhesive sheet in the technical field.

  The pressure-sensitive adhesive sheet of the present invention is formed by forming the pressure-sensitive adhesive layer on a support film. Generally, crosslinking of the pressure-sensitive adhesive composition is performed after application of the pressure-sensitive adhesive composition, but after crosslinking. It is also possible to transfer the pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition to a support film or the like.

  The method for forming the pressure-sensitive adhesive layer on the support film is not particularly limited. For example, the pressure-sensitive adhesive composition is applied to the support film, and the polymerization solvent is dried and removed, so that the pressure-sensitive adhesive layer is formed on the support film. It is produced by forming. 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 prepare a pressure-sensitive adhesive sheet, one or more solvents other than the polymerization solvent are newly added to the pressure-sensitive adhesive composition so that the pressure-sensitive adhesive composition can be uniformly applied on the support film. You may add to.

  Moreover, as a formation method of the adhesive layer at the time of manufacturing the adhesive sheet 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, extrusion coating using a die coater, and the like.

  The pressure-sensitive adhesive sheet of the present invention is usually prepared so that the pressure-sensitive adhesive layer has a thickness of 3 to 100 μm, preferably about 5 to 50 μm. It is preferable for the thickness of the pressure-sensitive adhesive layer to be in the above-mentioned range since it is easy to obtain an appropriate balance between removability and adhesion (adhesion). The pressure-sensitive adhesive sheet is formed by coating and forming the pressure-sensitive adhesive layer on one or both surfaces of various support films made of a plastic film such as a polyester film, or a porous material such as paper or nonwoven fabric. It is a form.

  The thickness of the support film which comprises the adhesive sheet using the adhesive composition of this invention is 5-200 micrometers normally, Preferably it is 10-125 micrometers, More preferably, it is about 20-100 micrometers. When the thickness of the support film is within the above range, it is preferable because the workability of bonding to an adherend (for example, a polarizing plate) and the workability of peeling from the adherend are excellent.

  For the support film, 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., acid treatment, alkali treatment, 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 film is more preferably a plastic 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 film 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 Polyolefin films such as propylene copolymer, ethylene / 1-butene copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, poly Polyester film such as butylene terephthalate, Polyacrylate film, Polystyrene film, Nylon 6, Nylon 6,6, Polyamide film such as partially aromatic polyamide, Polyvinyl chloride film, Polyvinylidene chloride film, Examples include polycarbonate films.

  In addition, when the pressure-sensitive adhesive sheet of the present invention is used for surface protection (used as a surface protection film), particularly when the support film is a plastic film subjected to antistatic treatment, surface protection when peeled off. This is preferable because charging of the film itself can be suppressed. In addition, since the pressure-sensitive adhesive composition obtained by crosslinking the pressure-sensitive adhesive composition having the above-described effects is provided, a surface protective film with reduced contamination on the adherend is obtained. For this reason, it becomes very useful as a surface protective film in the technical field related to optical and electronic components.

  The antistatic treatment applied to the support film (plastic film) is not particularly limited, but a method of providing an antistatic layer on at least one side of a commonly used support film or a kneading type antistatic agent in the support film. A kneading method is used. In addition, as a method of providing an antistatic layer on at least one side of the support film, a method of applying an antistatic resin or a conductive polymer comprising an antistatic agent and a resin component, a conductive resin containing a conductive substance, or a conductive A method for depositing or plating a substance is mentioned.

  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, sulfones Anionic antistatic agents with anionic functional groups such as acid salts, sulfate esters, phosphonates, phosphate esters, alkylbetaines and derivatives thereof, imidazolines and derivatives thereof, and amphoteric antistatic agents such as alanine and derivatives thereof A nonionic antistatic agent such as an agent, amino alcohol and derivatives thereof, glycerin and derivatives thereof, polyethylene glycol and derivatives thereof, or a monomer having an ion conductive group of the above cation type, anion type or zwitterionic type Examples thereof include ionic conductive polymers obtained by copolymerization. These antistatic agents may be used alone or in admixture of two or more.

  Examples of the cationic antistatic agent include quaternary ammonium groups such as alkyltrimethylammonium salts, acylamidopropyltrimethylammonium methosulfate, alkylbenzylmethylammonium salts, acylcholine chloride, and 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.

  Examples of the anionic antistatic agent include alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate ester salt, alkyl ethoxy sulfate ester salt, alkyl phosphate ester salt, and sulfonic acid group-containing styrene copolymer.

  Examples of the zwitterionic antistatic agent include alkylbetaines, alkylimidazolium betaines, and carbobetaine graft copolymers.

  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. can give.

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

  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 above-mentioned antistatic resin, conductive polymer, or conductive resin with a solvent such as an organic solvent or water, and applying this coating liquid to a plastic film and drying it. 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. 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. Law

  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. Within the above range, the plastic film is less likely to impair the heat resistance, solvent resistance, and flexibility, which is preferable.

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

  The thickness of the conductive material layer is usually 0.002 to 1 μm, preferably 0.005 to 0.5 μm. Within the above range, the plastic film is less likely to impair the heat resistance, solvent resistance, and flexibility, which is preferable.

  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 mass or less, preferably 0.05 to 10% by mass with respect to the total mass of the plastic film. Within the above range, the plastic film is less likely to impair the heat resistance, solvent resistance, and flexibility, which is preferable. The kneading method is not particularly limited as long as the antistatic agent can be uniformly mixed with the resin used for the plastic film. For example, a heating roll, a Banbury mixer, a pressure kneader, a biaxial kneader or the like is used. It is done.

  A separator (release liner) can be bonded to the pressure-sensitive adhesive sheet (surface protective film) of the present invention as needed for the purpose of protecting the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer.

  Examples of the material constituting the separator include paper and plastic film, and 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. It is preferable for it to be in the above-mentioned range since it is excellent in workability for bonding to the pressure-sensitive adhesive layer and workability for peeling from the pressure-sensitive adhesive layer. 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.

<Optical member>
The optical member (optical film) of the present invention is preferably protected by the pressure-sensitive adhesive sheet. By being protected by the adhesive sheet, the adhesive sheet is attached to an optical member (optical film) and then peeled off from the adherend at low speed and high speed (appropriate peeling force, removability). In addition, since it is excellent in workability, it is useful. In addition, after peeling off the pressure-sensitive adhesive sheet, repellency can be suppressed when an optical pressure-sensitive adhesive (such as a pressure-sensitive adhesive sheet or pressure-sensitive adhesive tape) is separately applied to the optical member (optical film), and the peel strength is further reduced. Can also be suppressed, which is useful. Furthermore, when antistatic treatment is performed (for example, when the adhesive layer is protected with an adhesive sheet using an antistatic agent), the optical member (optical film) as an adherend itself is imparted with antistatic properties. Therefore, it is very useful as an antistatic application in the technical field related to optical and electronic parts where charging is a particularly serious problem.

  In addition, the said adhesive sheet is used suitably for the use bonded to various optical members (For example, a liquid crystal cell, an optical polyester film, a touch panel member, etc.). The optical member here includes a laminate in which an adhesive layer formed by the adhesive composition of the present invention is provided on the optical member. This laminate typically has an aspect in which the pressure-sensitive adhesive layer on the optical member is protected by a separator (release liner). An optical member provided with such an adhesive layer is useful because it can be easily attached to the surface of a plastic cover lens panel, glass, liquid crystal cell, or the like.

  The optical member is not particularly limited, and examples thereof include a polarizing plate, a retardation plate, and a transparent conductive film (ITO film). Such an optical member may have a single layer structure made of the same material or a multilayer structure made of a plurality of materials.

  As the method for forming the pressure-sensitive adhesive layer on the optical member, as in the case of forming the pressure-sensitive adhesive layer on the support film (base material, support), a method of directly applying or a method of transferring is appropriately adopted. Can do. Typically, a method of transferring a pressure-sensitive adhesive layer formed on a separator (release liner) to the base surface of the optical member can be mentioned.

  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.

  In Tables 1 to 3, the monomer component (SP value of the monomer species) constituting the (meth) acrylic polymer (sometimes simply referred to as “polymer”) and the SP of the polymer based on the monomer ratio The values and SP values of the monomer components constituting the oligomer are shown. Table 4 shows the content of the pressure-sensitive adhesive composition (polymer used, oligomer, etc.), and Table 5 shows the evaluation results of the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition. It was.

[Preparation of polymer 1]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 100 parts by mass of 2-ethylhexyl acrylate (2EHA), 5 parts by mass of 4-hydroxybutyl acrylate (4HBA), 2, Charge 2'-azobisisobutyronitrile (0.2 parts by mass) and ethyl acetate (157 parts by mass), introduce nitrogen gas with gentle stirring, and maintain the liquid temperature in the flask at around 65 ° C for 6 hours. And a solution (40% by mass) of (meth) acrylic polymer 1 (polymer 1) was prepared. The polymer 1 had a weight average molecular weight (Mw) of 540,000 and a glass transition temperature (Tg) of −68 ° C.

[Preparation of polymer 2]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser, 100 parts by mass of 2-ethylhexyl acrylate (2EHA), 3 parts by mass of 2-hydroxyethyl acrylate (2HEA), and 2, as a polymerization initiator Charge 2'-azobisisobutyronitrile (0.2 parts by mass) and ethyl acetate (158 parts by mass), introduce nitrogen gas with gentle stirring, and maintain the liquid temperature in the flask at around 65 ° C for 6 hours. And a solution (40% by mass) of (meth) acrylic polymer 2 (polymer 2) was prepared. The polymer 2 had a weight average molecular weight (Mw) of 550,000 and a glass transition temperature (Tg) of −68 ° C.

[Preparation of polymer 3]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 13 parts by mass of 2-hydroxyethyl acrylate (2HEA), N-vinylpyrrolidone (NVP) ) 15 parts by mass, 9 parts by mass of methyl methacrylate (MMA), 0.1 part by mass of 2,2′-azobisisobutyronitrile as a polymerization initiator, 200 parts by mass of ethyl acetate, and nitrogen with gentle stirring Gas was introduced, and the temperature of the liquid in the flask was kept at around 65 ° C. to conduct a polymerization reaction for 6 hours to prepare a solution (40% by mass) of (meth) acrylic polymer 3 (polymer 3). The weight average molecular weight (Mw) of the said polymer 3 was 1,10,000, and the glass transition temperature (Tg) was -53 degreeC.

<Examples 1 and 10>
(Preparation of adhesive solution)
The polymer 1 solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and oligomer 1 (polyester polyol, PNMA-2016, manufactured by Kuraray Co., Ltd.) was added to 500 parts by mass (solid content 100 parts by mass) of acetic acid. 10 parts by weight of a solution diluted to 10% with ethyl (1 part by weight of solid content), as an alkali metal salt as an antistatic agent, lithium bis (trifluoromethanesulfonyl) imide (LiN (CF ₃ SO ₂ ) ₂ : LiTFSI, Tokyo 4 parts by mass (made by Kasei Kogyo Co., Ltd.) diluted to 5% with ethyl acetate (0.2 parts by mass solid content), as a cross-linking agent, isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX: C / HX) 3 parts by mass (solid content 3 parts by mass), 2 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) as a crosslinking catalyst (solid In addition minute 0.02 parts by weight), and mixed and stirred to prepare an acrylic adhesive solution.

<Examples 2 and 11>
(Preparation of adhesive solution)
Example 1 except that 10 parts by mass (solid content 1 part by mass) of an oligomer 2 (polyester polyol, P1020, manufactured by Kuraray Co., Ltd.) diluted to 10% with ethyl acetate was used in place of the oligomer 1 of Example 1. 1 was used to prepare an acrylic pressure-sensitive adhesive solution.

<Example 3>
(Preparation of adhesive solution)
Example 1 except that 10 parts by mass (solid content 1 part by mass) of an oligomer 3 (polyester polyol, P2030, manufactured by Kuraray Co., Ltd.) diluted to 10% with ethyl acetate was used instead of the oligomer 1 of Example 1. 1 was used to prepare an acrylic pressure-sensitive adhesive solution.

<Example 4>
(Preparation of adhesive solution)
Example 1 except that 10 parts by mass (solid content 1 part by mass) of an oligomer 4 (polyester polyol, P2011, manufactured by Kuraray Co., Ltd.) diluted to 10% with ethyl acetate was used in place of the oligomer 1 of Example 1. 1 was used to prepare an acrylic pressure-sensitive adhesive solution.

<Example 5>
(Preparation of adhesive solution)
Instead of the oligomer 1 of Example 1, the oligomer 1 (polyester polyol, PNMA-2016, manufactured by Kuraray Co., Ltd.) diluted to 10% with ethyl acetate 5 parts by mass (solid content 0.5 part by mass), and the oligomer 2 parts (polyester polyol, P1020, manufactured by Kuraray Co., Ltd.) 5 parts by mass (solid content 0.5 parts by mass) of 5 parts by mass (solid content 0.5 parts by mass) of a solution obtained by diluting 10% with ethyl acetate ) An acrylic pressure-sensitive adhesive solution was prepared in the same manner as in Example 1 except that it was used.

<Examples 6 and 7>
(Preparation of adhesive solution)
Example 1 except that the polymer 2 solution (40% by mass) was used in place of the polymer 1 solution (40% by mass) of Example 1 and the other additives were used in the amounts shown in Table 4. An acrylic pressure-sensitive adhesive solution was prepared in the same manner as described above.

<Examples 8 and 9>
(Preparation of adhesive solution)
Example 1 except that the polymer 3 solution (40% by mass) was used in place of the polymer 1 solution of Example 1 (40% by mass), and the other additives were used in the amounts shown in Table 4. An acrylic pressure-sensitive adhesive solution was prepared in the same manner as described above.

<Comparative Examples 1-5>
(Preparation of adhesive solution)
In the same manner as in Example 1 except that polyether-modified silicone (KF-353, manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the oligomer 1 of Example 1, and the blending amounts shown in Table 4 were used. An acrylic pressure-sensitive adhesive solution was prepared.

<Comparative Examples 6 to 10>
(Preparation of adhesive solution)
In the same manner as in Example 1, except that polyether-modified silicone (KF-6004, manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the oligomer 1 of Example 1, and the blending amounts shown in Table 4 were used. An acrylic pressure-sensitive adhesive solution was prepared.

<Comparative Example 11>
(Preparation of adhesive solution)
An acrylic pressure-sensitive adhesive solution was prepared in the same manner as in Example 1 except that the oligomer 1 of Example 1 was not used.

[Preparation of adhesive sheet]
The acrylic pressure-sensitive adhesive solution was applied to a polyethylene terephthalate film (thickness 38 μm) as a support film using an applicator, and heated at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 15 μm. Next, the surface of the pressure-sensitive adhesive layer was bonded with a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm), which is a separator having a silicone treatment on one side, to obtain pressure-sensitive adhesive sheets of Examples and Comparative Examples.

In addition, about Example 10 and Example 11, Example 10 used the adhesive sheet of Example 1, and Example 11 used the adhesive sheet of Example 2 for the adhesive sheet used when evaluating.
Further, as the adherends, Examples 1 to 9 and Comparative Examples 1 to 11 used TAC polarizing plates (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate), whereas Examples 10 and 11 were used. Used an HTX polarizing plate (manufactured by Kaneka Corporation, HTX, acrylic film).

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

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

<Measurement of glass transition temperature of (meth) acrylic polymer>
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 (2EHA): -70 ° C
4-hydroxybutyl acrylate (4HBA): -32 ° C
2-Hydroxyethyl acrylate (2HEA): -15 ° C
N-vinylpyrrolidone (NVP): 80 ° C
Methyl methacrylate (MMA): 105 ° C

<Low speed peeling force>
Polarizing plate (TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) or HTX polarizing plate (manufactured by Kaneka Corporation, acrylic film, width: 70 mm, length: 100 mm)) After being left 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 on the adherend at a pressure of 0.25 MPa and a speed of 0.3 m / min. An evaluation sample was prepared.
After the above lamination, after leaving for 30 minutes in an environment of 23 ° C. × 50% RH, a low speed peeling force when peeling at a peeling speed of 0.3 m / min (low speed peeling) and a peeling angle of 180 ° with a universal tensile tester. (N / 25 mm) was measured. The measurement was performed in an environment of 23 ° C. × 50% RH.

  The low-speed peeling force is preferably 1.0 N / 25 mm or less, more preferably 0.01 to 0.8 N / 25 mm, and still more preferably 0.02 to 0.6 N / 25 mm. When the low-speed peeling force exceeds 1.0 N / 25 mm, the pressure-sensitive adhesive sheet (protective film) becomes difficult to peel off from the adherend, and the peeling workability when the pressure-sensitive adhesive sheet becomes unnecessary is further deteriorated. This is not preferable because the adherend is damaged.

<High speed peeling force>
Polarizing plate (TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) or HTX polarizing plate (manufactured by Kaneka Corporation, acrylic film, width: 70 mm, length: 100 mm)) After being left 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 on the adherend at a pressure of 0.25 MPa and a speed of 0.3 m / min. An evaluation sample was prepared.
After the above lamination, after being left in an environment of 23 ° C. × 50% RH for 30 minutes, a high-speed peeling force when peeling at a peeling speed of 30 m / min (high-speed peeling) and a peeling angle of 180 ° using a universal tensile tester (N / 25 mm). The measurement was performed in an environment of 23 ° C. × 50% RH.

  In addition, it is preferable that the said high speed peeling force is 2.5 N / 25mm or less, More preferably, it is 0.1-2.0 N / 25mm, More preferably, it is 0.5-1.8 N / 25mm. When the high-speed peeling force exceeds 2.5 N / 25 mm, the pressure-sensitive adhesive sheet (protective film) is difficult to peel off from the adherend, and the peeling workability when the pressure-sensitive adhesive sheet becomes unnecessary is further deteriorated. This is not preferable because the adherend is damaged.

<Peeling force reduction rate>
(1) Peeling force to the surface of the polarizing plate after pressure peeling (peeling force (A))
The pressure-sensitive adhesive sheet prepared in Examples and the like was cut into a size of 70 mm in width and 130 mm in length, and after removing the separator, the acrylic sheet (thickness: 2 mm, width: 70 mm, length: 100 mm) that had been neutralized in advance. Bonded polarizing plate (TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) or HTX polarizing plate (manufactured by Kaneka Corporation, acrylic film, width: 70 mm, length: 100 mm) )) Was crimped with a hand roller at 0.2 MPa so that one end protruded 30 mm. Then, after leaving for 24 hours in an environment of 23 ° C. × 50% RH, the pressure-sensitive adhesive sheet was peeled from the polarizing plate surface with a universal tensile testing machine at a peeling speed of 0.3 m / min (low speed peeling) and a peeling angle of 180 °. It peeled. The measurement was performed in an environment of 23 ° C. × 50% RH.
Subsequently, a stretched polypropylene-based adhesive tape (manufactured by Nitto Denko, Danbron No. 3651, width: 25 mm, length 150 mm) was pressure-bonded to the same surface as the polarizing plate surface at 0.2 MPa with a hand roller. Then, after leaving for 30 minutes in an environment of 23 ° C. × 50% RH, the adhesive tape was peeled from the polarizing plate surface with a universal tensile tester at a peeling speed of 0.3 m / min (low speed peeling) and a peeling angle of 180 °. The peel force (A) (N / 25 mm) when peeled was measured. The measurement was performed in an environment of 23 ° C. × 50% RH.

(2) Peeling force on the surface of the polarizing plate before pressure peeling (peeling force (B))
With respect to the polarizing plate surface before pressure-bonding the pressure-sensitive adhesive sheet prepared in Examples, etc., a stretched polypropylene-based pressure-sensitive adhesive tape (manufactured by Nitto Denko Corporation, Danbron No. 3651, width: 25 mm, length 150 mm) with a hand roller, Crimping was performed at 0.2 MPa. Then, after leaving for 30 minutes in an environment of 23 ° C. × 50% RH, the adhesive tape was peeled from the polarizing plate surface with a universal tensile tester at a peeling speed of 0.3 m / min (low speed peeling) and a peeling angle of 180 °. The peel force (B) (N / 25 mm) when peeled was measured. The measurement was performed in an environment of 23 ° C. × 50% RH. The peeling force (B) was 6.5 N / 25 mm. Using this value as a reference value, it was applied to the following equation to calculate the peel force reduction rate of the pressure-sensitive adhesive sheets prepared in Examples and the like.
Peeling force decrease rate (%) = 100 × (peeling force (B) −peeling force (A)) / peeling force (B)

  The peel force reduction rate is preferably 40% or less, more preferably 30% or less, and still more preferably 20% or less. When the high-speed peeling force exceeds 40%, the adhesive force of the optical pressure-sensitive adhesive to be bonded later is lowered, which causes a decrease in adhesion reliability, which is not preferable. In addition, when the said high speed peeling force exceeded 40%, repelling was confirmed, the case where repelling was confirmed was evaluated as x, and the case where repelling was not evaluated was evaluated as (circle).

<Peeling voltage>
The pressure-sensitive adhesive sheet 1 prepared in Examples and the like was cut into a size of 70 mm in width and 130 mm in length, the separator was peeled off, and then the acrylic plate 3 (thickness: 2 mm, width: 70 mm, length: 100 mm) previously discharged. ) Bonded to the surface of the polarizing plate 2 (TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) surface (TAC surface), or HTX polarizing plate (manufactured by Kaneka Corporation, acrylic film) , Width: 70 mm, length: 100 mm) The surface (HTX surface)) was crimped at 0.2 MPa with a hand roller so that one end protruded 30 mm. Thereafter, the sample was left at 23 ° C. × 50% RH for 1 day, and then the sample was set at a predetermined position as shown in FIG. One end protruding 30 mm was fixed to an automatic winder (not shown) and peeled so that the peel angle was 150 ° and the peel speed was 10 m / min. The potential of the polarizing plate surface (peeling band voltage: absolute value, kV) generated at this time was measured with a potential measuring device 5 (KSD-0103, manufactured by Kasuga Denki Co., Ltd.) fixed at the center of the polarizing plate. The measurement was performed in an environment of 23 ° C. × 50% RH.

  The stripping voltage (absolute value) is preferably 1.0 kV or less, more preferably 0.8 kV or less, and still more preferably 0.5 kV or less. If the stripping voltage exceeds 1.0 kV, the panel element may be destroyed, which is not preferable.

<Contamination>
The pressure-sensitive adhesive sheet prepared in Examples and the like was cut into a size of 70 mm in width and 130 mm in length, and after removing the separator, the acrylic sheet (thickness: 2 mm, width: 70 mm, length: 100 mm) that had been neutralized in advance. Bonded polarizing plate (TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) or HTX polarizing plate (manufactured by Kaneka Corporation, acrylic film, width: 70 mm, length: 100 mm) )) Was crimped with a hand roller at 0.2 MPa so that one end protruded 30 mm. Thereafter, the measurement was allowed to stand in an environment of 23 ° C. × 50% RH for 24 hours.
24 hours after pressure bonding, the pressure-sensitive adhesive sheet prepared in Example 1 and the like was peeled off, and the surface of the polarizing plate was visually observed. When there was no residue on the polarizing plate surface, there was no contamination.

注）表４中の架橋剤、帯電防止剤、及び、オリゴマーは、使用する(メタ)アクリル系ポリマー１００質量部(固形分)に対する配合量(質量部：固形分)を示した。また、（−）は使用していないことを示す。

Note) The crosslinking agent, antistatic agent, and oligomer in Table 4 indicate the blending amount (part by mass: solid content) relative to 100 parts by mass (solid content) of the (meth) acrylic polymer to be used. Moreover, (-) shows not using.

  From the evaluation results in Table 5 above, it was confirmed that in all examples, the low speed / high speed peel force and the peel force reduction rate were excellent, and thus the adhesiveness, re-peelability, and workability were excellent. In addition, the stripping voltage was suppressed, the antistatic property was excellent, and the occurrence of repelling and contamination were suppressed. Therefore, it was also confirmed that it was useful as a surface protecting application for optical members and the like.

  On the other hand, in the comparative example, none of the characteristics satisfied like the example, and it was confirmed that the characteristic was inferior to that of the example. In particular, in Comparative Examples 1 to 10, repellency was confirmed because an oligomer composed of a monomer component having a specific SP value was not used. In Comparative Example 11, since the oligomer itself was not used, the antistatic agent was not concentrated at the interface between the adherend and the adhesive, resulting in poor antistatic properties.

DESCRIPTION OF SYMBOLS 1 Adhesive sheet 2 Polarizing plate 3 Acrylic board 4 Fixing stand 5 Potential measuring device

Claims (9)

(Meth) acrylic polymer containing 50 to 99.9% by weight of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms and a hydroxyl group-containing (meth) acrylic monomer as a monomer component And an adhesive composition containing an ether group-containing oligomer,
The SP value of the monomer component constituting the ether group-containing oligomer is represented by the following formula (1):
The SP value of the monomer component constituting the ether group-containing oligomer is greater than the SP value of the (meth) acrylic polymer,
0.2-10 mass parts of said ether group containing oligomers are contained with respect to 100 mass parts of said (meth) acrylic-type polymers, The adhesive composition characterized by the above-mentioned.
SP = (δd ² + δp ² + δh ² ) ^0.5 (1)
(In the formula (1), δd, δp, and δh represent a dispersion term, a polar term, and a hydrogen bond term in the Hansen solubility parameter, respectively, and the unit is (MPa) ^1/2 .) The pressure-sensitive adhesive composition according to claim 1, wherein the ether group-containing oligomer has a weight average molecular weight of 800 to 6000. The pressure-sensitive adhesive composition according to claim 1 or 2, comprising an ionic compound. The pressure-sensitive adhesive composition according to claim 3, wherein the ionic compound is an alkali metal salt and / or an ionic liquid. A pressure-sensitive adhesive sheet, wherein a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to claim 1 is formed on at least one side of a support film. The pressure-sensitive adhesive sheet according to claim 5, wherein the peel force reduction rate measured is 40% or less based on the following formula (2).
Peeling force reduction rate (%) = 100 × (peeling force (B) −peeling force (A)) / peeling force (B) (2)
(In the formula, peeling force (A) means that the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet is peeled off after being attached to the surface of the polarizing plate at 23 ° C. for 30 minutes, and then stretched polypropylene-based pressure-sensitive adhesive tape on the surface of the polarizing plate. Shows the peel force at a peeling speed of 0.3 m / min after sticking for 30 minutes at 23 ° C. The peel force (B) refers to the sticky surface of a stretched polypropylene-based pressure-sensitive adhesive tape without sticking the pressure-sensitive adhesive sheet. Is applied to the surface of the polarizing plate at 23 ° C. for 30 minutes, and the peeling force at a peeling speed of 0.3 m / min is shown.) The adhesive force of the pressure-sensitive adhesive layer is attached to the surface of the polarizing plate at 23 ° C. for 30 minutes, and then the peeling force at a peeling speed of 30 m / min is 2.5 N / 25 mm or less. The adhesive sheet as described. The adhesive surface of the pressure-sensitive adhesive layer is pasted on the surface of a polarizing plate at 23 ° C. × 50% RH for 24 hours, and then the stripping voltage (absolute value) at a stripping rate of 10 m / min is 1.0 kV or less. The pressure-sensitive adhesive sheet according to claim 5. An optical member that is protected by the pressure-sensitive adhesive sheet according to claim 5.

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