JP6188595B2 - Adhesive composition, adhesive layer, and adhesive sheet - Google Patents

Description

  The present invention relates to an adhesive composition, an adhesive layer, and an adhesive sheet.

  The pressure-sensitive adhesive sheet using the pressure-sensitive adhesive composition of the present invention is used for plastic products and the like that are likely to generate static electricity. Especially, it is useful as a surface protective film used for the purpose of protecting the surface of an optical member such as a polarizing plate, a wave plate, a retardation plate, an optical compensation film, a reflection sheet, and a brightness enhancement film used for a liquid crystal display.

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

  The surface protective film is generally used for the purpose of sticking to a body to be protected through an adhesive applied to the support film side and preventing scratches and dirt generated during processing and transportation of the body to be protected. For example, a panel of a liquid crystal display is formed by bonding an optical member such as a polarizing plate or a wave plate to a liquid crystal cell via an adhesive. As for these optical members, the surface protection film is bonded together through the adhesive, and the damage and dirt which arise at the time of a process of a to-be-protected body and conveyance are prevented. And this surface protection film peels and is removed in the stage which became unnecessary.

  In general, since the surface protective film and the optical member are made of a plastic material, they have high electrical insulation, and static electricity is generated during friction and peeling. Accordingly, static electricity is generated even when the surface protective film is peeled off from the optical member such as a polarizing plate. When a voltage is applied to the liquid crystal while the static electricity generated at this time remains, the orientation of the liquid crystal molecules is changed. Loss and panel defects may occur.

  Furthermore, the presence of static electricity has the potential to attract dust and debris and cause workability degradation. Therefore, various antistatic treatments are applied to the surface protective film in order to solve the above-described problems.

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

  Moreover, the adhesive sheet (for example, refer patent document 2) which made the adhesive layer contain the antistatic agent is disclosed. In such an adhesive sheet, an antistatic agent composed of propylene glycol and an alkali metal salt is added to the acrylic adhesive in order to suppress bleeding of the antistatic agent on the adhesive surface. However, even if such an adhesive sheet is used, a bleeding phenomenon such as an antistatic agent is unavoidable. As a result, when it is actually applied to a surface protective film, if it is treated under time or high temperature conditions, There is a possibility that the surface protection film partially lifts from the object to be protected.

  Furthermore, when peeling the film from the optical member, it is easy to prevent inconveniences such as disorder of alignment of the liquid crystal cell, expansion of the cell gap, peeling of the optical member from the liquid crystal cell due to distortion phenomenon accompanying peeling. It must be peelable. In recent years, as the screen of a liquid crystal panel is increased, the protective film itself is also increased in area and the peeling speed is increased, so that further light peeling is desired.

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

  Therefore, the object of the present invention is to prevent the problem of the conventional antistatic pressure-sensitive adhesive sheet, and to prevent the non-antistatic adherend from being charged when it is peeled off. The object is to provide a reduced pressure-sensitive adhesive composition excellent in removability, and a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, and a surface protective film using the pressure-sensitive adhesive composition.

  That is, the pressure-sensitive adhesive composition of the present invention has a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component and an acid value of 1.0 or less. And an alkali metal salt and an organopolysiloxane having a polyoxyalkylene side chain, and the total of the alkali metal salt and the organopolysiloxane is 0.1% relative to 100 parts by weight of the (meth) acrylic polymer. 15 to 4 parts by weight. By using the pressure-sensitive adhesive composition of the present invention, anti-static treatment can be performed on an adherend (protected body) that has not been subjected to antistatic treatment when peeled, and contamination to the adherend is prevented. It is possible to obtain a pressure-sensitive adhesive composition excellent in reduction and removability. Further, it is presumed that by simultaneously using an alkali metal salt and an organopolysiloxane having a polyoxyalkylene side chain, the efficiency of ion conductivity is increased, and charging characteristics can be expressed on the protected object. Moreover, it is estimated that the contamination by a bleed phenomenon can be reduced by the balance of compatibility with an acrylic polymer. And it is presumed that the surface free energy on the surface of the pressure-sensitive adhesive is reduced by the organopolysiloxane having a polyoxyalkylene side chain, thereby enabling removability.

(式中、Ｒ_１は１価の有機基、Ｒ_２，Ｒ_３及びＲ_４はアルキレン基、Ｒ_５は水酸基もしくは有機基、ｍ及びｎは０〜１０００の整数。但し、ｍ,ｎが同時に０となることはない。ａ及びｂは０〜１００の整数。但し、ａ,ｂが同時に０となることはない。) In the pressure-sensitive adhesive composition of the present invention, the organopolysiloxane is preferably represented by the following formula.

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

  In the pressure-sensitive adhesive composition of the present invention, the alkali metal salt is preferably a lithium salt.

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer preferably further contains a hydroxyl group-containing (meth) acrylic monomer as a monomer component.

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer further contains 5.0 wt. Of an alkylene oxide group-containing reactive monomer having an average addition mole number of oxyalkylene units of 3 to 40 as a monomer component. % Or less is preferable.

  The pressure-sensitive adhesive layer of the present invention is preferably a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition.

  The pressure-sensitive adhesive sheet of the present invention is preferably formed by forming the pressure-sensitive adhesive layer on one side or both sides of a support film.

  In the pressure-sensitive adhesive sheet of the present invention, the support film is preferably a plastic film subjected to an antistatic treatment.

  The pressure-sensitive adhesive sheet of the present invention has a 180 ° peel adhesive strength of 0.25 N / 25 mm or less at a peeling rate of 0.3 m / min under the condition of 23 ° C. × 50% RH with respect to the polarizing plate surface of the pressure-sensitive adhesive layer. Under the conditions of 23 ° C. × 50% RH, the 180 ° peel adhesive strength at a peeling speed of 30 m / min is preferably 3.0 N / 25 mm or less.

The schematic block diagram of the electric potential measurement part used for the measurement of peeling band voltage in an Example.

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

  The pressure-sensitive adhesive composition of the present invention includes, as a monomer component, a (meth) acrylic polymer having a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a main component, an alkali metal salt, and polyoxy An adhesive composition containing an organopolysiloxane having an alkylene side chain, wherein the acid value of the (meth) acrylic polymer is 1.0 or less, and relative to 100 parts by weight of the (meth) acrylic polymer The total of the alkali metal salt and the organopolysiloxane is 0.15 to 4 parts by weight.

  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 said (meth) acrylic-type monomer is contained and it is a (meth) acrylic-type polymer which has adhesiveness, it will not specifically limit.

  As the monomer component of the (meth) acrylic polymer of the present invention, a (meth) acrylate having an alkyl group having 1 to 14 carbon atoms can be obtained because the balance of compatibility with the alkali metal salt and excellent adhesive properties are obtained. Preferably, it is a (meth) acrylate having an alkyl group having 6 to 14 carbon atoms. As said (meth) acrylate, 1 type (s) or 2 or more types can be used with a main component.

  The (meth) acrylic polymer mainly composed of a (meth) acrylate having an alkyl group having 1 to 14 carbon atoms has a monomer component of (meth) acrylate having an alkyl group having 1 to 14 carbon atoms. A (meth) acrylic polymer containing 9% by weight is preferred, and a (meth) acrylic polymer containing 60 to 95% by weight is more preferred. When the monomer component is within the above range, it is preferable from the viewpoint of obtaining appropriate wettability and cohesive strength in the pressure-sensitive adhesive composition.

  In the present invention, specific examples of the (meth) acrylate 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, etc. Fried That.

  Especially, when using the adhesive sheet of this invention as a surface protection film, 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, etc. Suitable examples include (meth) acrylates having an alkyl group having 6 to 14 carbon atoms. By using (meth) acrylate having an alkyl group having 6 to 14 carbon atoms, it becomes easy to control the adhesive force to the adherend to be low, and the removability is excellent.

  The (meth) acrylic polymer used in the present invention is a (meth) acrylic polymer having an acid value of 1.0 or less, and preferably has an acid value of 0.5 or less. In the case of a (meth) acrylic polymer having an acid value exceeding 1.0, the adhesive strength to the protected body is increased, and the antistatic property may not be obtained. These phenomena are caused by the presence of a large number of carboxyl groups having a large polar action in the (meth) acrylic polymer skeleton, so that the adhesive force to the protected object is increased. It is presumed that due to the interaction, ionic conduction was hindered and the conduction efficiency was lowered. Therefore, in the present invention, in order to make the acid value 1.0 or less, a (meth) acrylate system which does not substantially contain an acrylate and / or methacrylate having an acidic functional group such as a carboxyl group or a sulfonate group as a constituent unit. It is necessary to use a polymer. Specifically, for example, when a (meth) acrylic polymer obtained by copolymerizing 2-ethylhexyl acrylate and acrylic acid which is a monomer having a carboxyl group is used, the total amount of 2-ethylhexyl acrylate and acrylic acid is 100 parts by weight. By setting acrylic acid to 0.13 parts by weight or less, the acid value can be adjusted to 1.0 or less.

  In addition, the acid value of the (meth) acrylic polymer in the present invention refers to the number of mg of potassium hydroxide required to neutralize free fatty acid, resin acid and the like contained in 1 g of a sample.

  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 adhesive performance, and the glass transition temperature or peeling of the (meth) acrylic polymer. 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.

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

  By using the (meth) acrylic monomer having a hydroxyl group, it is easy to control the crosslinking of the pressure-sensitive adhesive composition, and thus it is easy to control the balance between improvement of wettability due to flow and reduction of adhesive strength in peeling. Become. Furthermore, unlike the above-mentioned carboxyl group and sulfonate group, which can generally act as a crosslinking site, the hydroxyl group has an appropriate interaction with an alkali metal salt and an organopolysiloxane having a polyoxyalkylene side chain. Also in this aspect, it can be suitably used. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxyoctyl. (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxy Examples thereof include ethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.

  In the case where the (meth) acrylic monomer having a hydroxyl group is included, the (meth) acrylic monomer having a hydroxyl group is 0.1 to 10 weights with respect to 100 parts by weight of all the structural units of the (meth) acrylic polymer. Part is preferable, and 0.5 to 8 parts by weight is more preferable. 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, in the (meth) acrylic polymer used in the present invention, other polymerizable monomers other than the above monomers include, for example, improved cohesion and heat resistance of cyano group-containing monomers, vinyl ester monomers, aromatic vinyl monomers and the like. Components, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, N-acryloylmorpholine, components having a functional group that serves as a crosslinking base, such as vinyl ether monomer, are used as appropriate. be able to. These monomer compounds may be used alone or in admixture of two or more.

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

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

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

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

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

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

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

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

  In the present invention, the other polymerizable monomers may be used singly or in combination of two or more, but the total content is a monomer component of the (meth) acrylic polymer. The content is preferably 0 to 40% by weight, more preferably 0 to 35% by weight, and particularly preferably 0 to 30% by weight. By using the other polymerizable monomer within the above range, good interaction with the alkali metal salt and good removability can be appropriately adjusted.

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer further contains 5.0 wt. Of an alkylene oxide group-containing reactive monomer having an average addition mole number of oxyalkylene units of 3 to 40 as a monomer component. % Or less is preferable.

  Moreover, as an average addition mole number of the oxyalkylene unit to the said alkylene oxide group containing reactive monomer, it is preferable that it is 3-40 from a compatible viewpoint with an alkali metal salt, and it is more preferable that it is 4-35. Preferably, it is 5-30. When the average number of added moles is 3 or more, the effect of reducing the contamination of the protected object tends to be obtained efficiently. Moreover, when the said average addition mole number is larger than 40, since interaction with an alkali metal salt is large, and there exists a tendency for an adhesive composition to become a gel form and for coating to become difficult, it is unpreferable. Note that the terminal of the oxyalkylene chain may be a hydroxyl group or may be substituted with another functional group.

  The alkylene oxide group-containing reactive monomer may be used singly or in combination of two or more, but the total content is (meth) acrylic polymer monomer component 5.0. It is preferably not more than wt%, more preferably not more than 4.0 wt%, particularly preferably not more than 3.0 wt%, and still more preferably not more than 1.0 wt%. When the content of the alkylene oxide group-containing reactive monomer exceeds 5.0% by weight, the interaction with the alkali metal salt is increased, ion conduction is hindered, and the antistatic property is lowered, which is not preferable.

  Examples of the oxyalkylene unit of the alkylene oxide group-containing reactive monomer in the present invention include those having an alkylene group having 1 to 6 carbon atoms, such as an oxymethylene group, an oxyethylene group, an oxypropylene group, and an oxybutylene group. Can be given. The hydrocarbon group of the oxyalkylene chain may be linear or branched.

  Furthermore, the alkylene oxide group-containing reactive monomer is more preferably a reactive monomer having an ethylene oxide group. By using a (meth) acrylic polymer having a reactive monomer having an ethylene oxide group as a base polymer, the compatibility between the base polymer and the alkali metal salt is improved, and bleed to the adherend is suitably suppressed, and low A fouling pressure-sensitive adhesive composition is obtained.

  Examples of the alkylene oxide group-containing reactive monomer in the present invention include (meth) acrylic acid alkylene oxide adducts and reactive surfactants having reactive substituents such as acryloyl group, methacryloyl group, and allyl group in the molecule. Etc.

  Specific examples of the (meth) acrylic acid alkylene oxide adduct include, for example, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, polyethylene glycol-polybutylene glycol (meth) ) Acrylate, polypropylene glycol-polybutylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, butoxy polyethylene glycol (meth) acrylate, octoxy polyethylene glycol (meth) acrylate, lauroxy polyethylene Glycol (meth) acrylate, stearoxy polyethylene glycol Le (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate, octoxypolyethylene glycol - polypropylene glycol (meth) acrylate.

  Specific examples of the reactive surfactant include, for example, an anionic reactive surfactant having a (meth) acryloyl group or an allyl group, a nonionic reactive surfactant, and a cationic reactive surfactant. Can be given.

  Examples of the anionic reactive surfactant include those represented by formulas (A1) to (A10).

[R ₁ in Formula (A1) represents hydrogen or a methyl group, R ₂ represents a hydrocarbon group having 1 to 30 carbon atoms or an acyl group, X represents an anionic hydrophilic group, R ₃ and R ₄ are The alkylene groups having 1 to 6 carbon atoms are the same or different, and the average added mole number m and n are 0 to 40, where (m + n) represents 3 to 40. ].

[R ₁ in Formula (A2) represents hydrogen or a methyl group, R ₂ and R ₇ are the same or different, represent an alkylene group having ₁ to ₆ carbon atoms, and R ₃ and R ₅ are the same or different, Represents hydrogen or an alkyl group, R ₄ and R ₆ are the same or different and represent hydrogen, an alkyl group, a benzyl group or a styrene group, X represents an anionic hydrophilic group, and the average number of added moles m and n are 0 to 40, where (m + n) represents a number from 3 to 40. ].

[R ₁ in Formula (A3) represents hydrogen or a methyl group, R ₂ represents an alkylene group having 1 to 6 carbon atoms, X represents an anionic hydrophilic group, and the average number of added moles n is 3 to 40 Represents a number. ].

[R ₁ in Formula (A4) represents hydrogen or a methyl group, R ₂ represents a hydrocarbon group or acyl group having 1 to 30 carbon atoms, and R ₃ and R ₄ may be the same or different, and 6 represents an alkylene group, X represents an anionic hydrophilic group, the average added mole number m and n are 0 to 40, and (m + n) represents a number of 3 to 40. ].

[R ₁ in Formula (A5) represents a hydrocarbon group, an amino group, or a carboxylic acid residue, R ₂ represents an alkylene group having 1 to 6 carbon atoms, X represents an anionic hydrophilic group, and average added mole The number n represents an integer of 3 to 40. ].

[In Formula (A6), R ₁ represents a hydrocarbon group having 1 to 30 carbon atoms, R ₂ represents hydrogen or a hydrocarbon group having 1 to 30 carbon atoms, R ₃ represents hydrogen or a propenyl group, and R ₄ represents An alkylene group having 1 to 6 carbon atoms is represented, X represents an anionic hydrophilic group, and the average added mole number n represents a number of 3 to 40. ].

[R ₁ in Formula (A7) represents hydrogen or a methyl group, R ₂ and R ₄ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and R ₃ represents a hydrocarbon having 1 to 30 carbon atoms. Represents a group, M represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group, and the average number of added moles m and n is 0 to 40, where (m + n) represents a number of 3 to 40. ].

[And _{R 1} and _{R 5} in the formula (A8) the same or different, represent a hydrogen or a methyl group, _{R 2} and _{R 4} are the same or different and each represents an alkylene group having a carbon number of 1 to 6, _{R 3} is Represents a hydrocarbon group having 1 to 30 carbon atoms, M represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group, and the average number of added moles m and n is 0 to 40, provided that (m + n) is 3 to 40 Represents a number. ].

[R ₁ in Formula (A9) represents an alkylene group having 1 to 6 carbon atoms, R ₂ represents a hydrocarbon group having 1 to 30 carbon atoms, and M represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group. The average added mole number n represents a number of 3 to 40. ].

[R ₁ , R ₂ and R _{3 in} Formula (A10) are the same or different and represent hydrogen or a methyl group, and R ₄ represents a hydrocarbon group having 0 to 30 carbon atoms (in the case of 0 carbon atoms, R ₄ R ₅ and R ₆ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, X represents an anionic hydrophilic group, and average added mole numbers m and n are 0 to 40, where (m + n) represents a number from 3 to 40. ].

  X in the above formulas (A1) to (A6) and (A10) represents an anionic hydrophilic group. Examples of the anionic hydrophilic group include those represented by the following formulas (a1) to (a2).

[M ₁ in Formula (a1) represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group. ].

[M ₂ and M _{3 in} Formula (a2) are the same or different and represent hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group. ].

  Examples of nonionic reactive surfactants include those represented by formulas (N1) to (N6).

[R ₁ in Formula (N1) represents hydrogen or a methyl group, R ₂ represents a hydrocarbon group or an acyl group having 1 to 30 carbon atoms, and R ₃ and R ₄ may be the same or different, and 6 represents an alkylene group, and average addition mole numbers m and n are 0 to 40, where (m + n) represents a number of 3 to 40. ].

[R ₁ in Formula (N2) represents hydrogen or a methyl group, R ₂ , R ₃ and R ₄ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and the average number of added moles n, m, And l represents 0 to 40, and (n + m + 1) represents a number from 3 to 40. ].

[R ₁ in Formula (N3) represents hydrogen or a methyl group, R ₂ and R ₃ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and R ₄ represents a hydrocarbon having 1 to 30 carbon atoms. A group or an acyl group, the average number of added moles m and n is 0 to 40, where (m + n) represents a number of 3 to 40. ].

[R ₁ and R _{2 in} formula (N4) are the same or different and each represents a hydrocarbon group having 1 to 30 carbon atoms, R ₃ represents hydrogen or a propenyl group, and R ₄ represents an alkylene having 1 to 6 carbon atoms Represents the group, and the average addition mole number n represents a number of 3 to 40. ].

[In formula (N5), R ₁ and R ₃ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms; R ₂ and R ₄ are the same or different and represent hydrogen or a hydrocarbon having 1 to 30 carbon atoms; A group or an acyl group, and the average addition mole numbers m and n are 0 to 40, where (m + n) represents a number of 3 to 40. ].

[R ₁ , R ₂ and R _{3 in} Formula (N6) are the same or different and represent hydrogen or a methyl group, and R ₄ represents a hydrocarbon group having 0 to 30 carbon atoms (in the case of 0 carbon atoms, R ₄ R ₅ and R ₆ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and the average added mole numbers m and n are 0 to 40, provided that (m + n) is 3 to 3. The number of 40 is represented. ].

  Further, specific examples of commercially available alkylene oxide group-containing reactive monomers include, for example, Blemmer PME-400, Blemmer PME-1000, Blemmer 50POEP-800B (all of which are manufactured by NOF Corporation), Latemul PD-420. Latemul PD-430 (all are manufactured by Kao Corporation), Adeka Rea Soap ER-10, Adeka Rea Soap NE-10 (all are manufactured by Asahi Denka Kogyo Co., Ltd.), and the like.

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

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

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

  The pressure-sensitive adhesive composition of the present invention contains an alkali metal salt in addition to the (meth) acrylic polymer and the organopolysiloxane having a polyoxyalkylene side chain. The total of the alkali metal salt and the organopolysiloxane is 0.15 to 4 parts by weight, preferably 0.2 to 3 parts by weight, with respect to 100 parts by weight of the (meth) acrylic polymer. More preferably, it is 0.2-2 weight part, More preferably, it is 0.2-1.5 weight part. It is preferable for it to be in the above-mentioned range since it is easy to achieve both antistatic properties and low contamination.

  The content ratio of the alkali metal salt and the organopolysiloxane is preferably 20:80 to 50:50, more preferably 25:75 to 45:55, and more preferably 30:70 to 50:50. More preferably, it is 40:60, and particularly preferably 30:70. If it is less than 20:80, sufficient charging characteristics cannot be obtained, and if it exceeds 50:50, the viscosity tends to increase, and it tends to be difficult to adjust the antistatic solution.

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

  Regarding the blending amount of the alkali metal salt used in the pressure-sensitive adhesive composition, when the content ratio of the alkali metal salt and the organopolysiloxane is, for example, 20:80 by weight, the (meth) acrylic polymer 100 It is preferable to mix 0.03-0.8 parts by weight of alkali metal salt with respect to parts by weight, more preferably 0.04-0.6 parts by weight, and 0.04-0.4 parts by weight. It is more preferable to mix, and 0.04 to 0.3 parts by weight is particularly preferable. If the amount is less than 0.03 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if the amount is more than 0.8 parts by weight, contamination tends to occur.

  Moreover, when the content ratio of the alkali metal salt and the organopolysiloxane is, for example, 50:50 by weight, the alkali metal salt is added in an amount of 0.075 to 2 to 100 parts by weight of the (meth) acrylic polymer. It is preferable to mix 0.0 part by weight, more preferably 0.1 to 1.5 part by weight, further preferably 0.1 to 1.0 part by weight, and 0.1 to 0.75 part by weight. Part blending is particularly preferred. If the amount is less than 0.075 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if the amount is more than 2.0 parts by weight, contamination tends to occur.

  When the content ratio of the alkali metal salt and the organopolysiloxane is, for example, 30:70 by weight, the alkali metal salt is 0.045 to 1.2 with respect to 100 parts by weight of the (meth) acrylic polymer. It is preferable to mix | blend a weight part, It is more preferable to mix | blend 0.06-0.9 weight part, It is further more preferable to mix | blend 0.06-0.6 weight part, 0.06-0.45 weight part mixing | blending It is particularly preferable to do this. If the amount is less than 0.045 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if it exceeds 1.2 parts by weight, contamination tends to occur.

(式中、Ｒ_１は１価の有機基、Ｒ_２，Ｒ_３及びＲ_４はアルキレン基、Ｒ_５は水酸基もしくは有機基、ｍ及びｎは０〜１０００の整数。但し、ｍ,ｎが同時に０となることはない。ａ及びｂは０〜１００の整数。但し、ａ,ｂが同時に０となることはない。) As the organopolysiloxane used in the pressure-sensitive adhesive composition, a known organopolysiloxane having a polyoxyalkylene side chain can be used as appropriate, and is preferably represented by the following formula.

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

  In the organopolysiloxane, the end of the polyoxyalkylene side chain is more preferably a hydroxyl group. By using the organopolysiloxane, it is possible to develop an antistatic property to the object to be protected, which is effective.

  About the compounding quantity of the said organopolysiloxane, when the content rate of the said alkali metal salt and the said organopolysiloxane is 20:80 by weight ratio, with respect to 100 weight part of the said (meth) acrylic-type polymer, 0.12-3.2 parts by weight of the organopolysiloxane is preferably blended, more preferably 0.16-2.4 parts by weight, and even more preferably 0.16-1.6 parts by weight. Preferably, 0.16 to 1.2 parts by weight is blended. If the amount is less than 0.12 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if the amount is more than 3.2 parts by weight, contamination tends to occur.

  Moreover, when the content ratio of the alkali metal salt and the organopolysiloxane is, for example, 50:50 by weight, the organopolysiloxane is added in an amount of 0.075 to 100 parts by weight of the (meth) acrylic polymer. It is preferable to mix | blend 2.0 weight part, It is more preferable to mix | blend 0.1-1.5 weight part, It is further more preferable to mix | blend 0.1-1.0 weight part, 0.1-0.75 It is particularly preferable to add part by weight. If the amount is less than 0.075 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if the amount is more than 2.0 parts by weight, contamination tends to occur.

  When the content ratio of the alkali metal salt and the organopolysiloxane is, for example, 30:70 by weight, the organopolysiloxane is added in an amount of 0.105 to 2.0.5 with respect to 100 parts by weight of the (meth) acrylic polymer. It is preferable to mix 8 parts by weight, more preferably 0.14 to 2.1 parts by weight, still more preferably 0.14 to 1.4 parts by weight, and 0.14 to 1.05 parts by weight. It is particularly preferable to blend. If the amount is less than 0.105 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if the amount is more than 2.8 parts by weight, contamination tends to occur.

Moreover, as said organopolysiloxane in this invention, the following structures can be used, for example. Specifically, R ₁ in the formula is a monovalent group exemplified by an alkyl group such as a methyl group, an ethyl group and a propyl group, an aryl group such as a phenyl group and a tolyl group, or an alkyl group such as a benzyl group and a phenethyl group. It is an organic group, and each may have a substituent such as a hydroxyl group. R ₂ , R ₃ and R ₄ may be an alkylene group having 1 to 8 carbon atoms such as a methylene group, an ethylene group or a propylene group. Here, R ₃ and R ₄ are different alkylene groups, and R ₂ may be the same as or different from R ₃ or R ₄ . One of R ₃ and R ₄ is preferably an ethylene group or a propylene group in order to increase the concentration of an alkali metal salt that can be dissolved in the polyoxyalkylene side chain. R ₅ may be an alkyl group such as a methyl group, an ethyl group or a propyl group, or a monovalent organic group exemplified by an acyl group such as an acetyl group or a propionyl group, each having a substituent such as a hydroxyl group. May be. These compounds may be used alone or in combination of two or more. Moreover, you may have reactive substituents, such as a (meth) acryloyl group, an allyl group, and a hydroxyl group, in a molecule | numerator. Among the organopolysiloxanes having a polyoxyalkylene side chain, an organopolysiloxane having a polyoxyalkylene side chain having a hydroxyl terminal is presumed to be easily balanced.

  Specific examples of the organopolysiloxane include, for example, trade names KF-351A, KF-353, KF-945, KF-6011, KF-889, and KF-6004 (manufactured by Shin-Etsu Chemical Co., Ltd.). FZ-2122, FZ-2164, FZ-7001, SH8400, SH8700, SF8410, SF8422 (above, manufactured by Toray Dow Corning), TSF-4440, TSF-4445, TSF-4442, TSF-4460 (Momentive Performance Materials) Manufactured by the same company), BYK-333, BYK-377, BYK-UV3500, BYK-UV3570 (manufactured by BYK Japan). These compounds may be used alone or in combination of two or more.

  The pressure-sensitive adhesive layer of the present invention is preferably formed by crosslinking the pressure-sensitive adhesive composition. A pressure-sensitive adhesive sheet with more excellent heat resistance can be obtained by appropriately adjusting the structural unit, the structural ratio, the selection of the crosslinking agent, the addition ratio, and the like of the (meth) acrylic polymer.

  As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound, and the like are used. Among these, an isocyanate compound and an epoxy compound are particularly preferably used mainly from the viewpoint of obtaining an appropriate cohesive force. These compounds may be used alone or in combination of two or more.

  Examples of the isocyanate compound include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone. Arocyclic isocyanates such as diisocyanate, aromatic isocyanates such as 2,4-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 ( Product name Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd., isocyanurate of hexamethylene diisocyanate Body (trade name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) isocyanate, such as - such as theft adduct, and the like. These compounds may be used alone or in combination of two or more.

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

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

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

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

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

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

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

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

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

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

  Examples of the cationic photopolymerization initiator include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, and organometallic complexes such as iron-allene complexes, titanocene complexes, and arylsilanol-aluminum complexes. Nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenol sulfonic acid ester, diazonaphthoquinone, N-hydroxyimide sulfonate and the like. These compounds may be used alone or in combination of two or more.

  The photopolymerization initiator is usually added in an amount of 0.1 to 10 parts by weight and preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the (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.

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

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

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

  Moreover, it is preferable that the adhesive sheet of this invention forms the adhesive layer formed by bridge | crosslinking the adhesive composition in any one of the said on the single side | surface or both surfaces of a support film. According to the pressure-sensitive adhesive sheet of the present invention, it is provided with a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition having the above-described effects, so that it is possible to prevent the object to be protected from being antistatic when peeled off, The pressure-sensitive adhesive sheet is reduced in contamination to the protected body. For this reason, it becomes very useful as an antistatic pressure-sensitive adhesive sheet in a technical field related to optical and electronic components in which charging and contamination are particularly serious problems.

  The pressure-sensitive adhesive sheet of the present invention is formed by forming the pressure-sensitive adhesive layer on a support film. In this case, the pressure-sensitive adhesive composition is generally crosslinked after application of the pressure-sensitive adhesive composition. However, it is also possible to transfer the pressure-sensitive adhesive layer comprising the crosslinked 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 to form the pressure-sensitive adhesive layer 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 composition so that the pressure-sensitive adhesive composition can be uniformly applied on the support film. May be.

  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 within the above range because it is easy to obtain an appropriate balance between removability and adhesiveness. 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 which uses the adhesive composition of this invention is 5-200 micrometers normally, Preferably it is about 10-100 micrometers. When the thickness of the support film is within the above range, it is preferable because the workability for bonding to the adherend and the workability for 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.

  In addition, the pressure-sensitive adhesive sheet of the present invention has a 180 ° peel adhesive strength (pull rate of 0.3 m / min) at 23 ° C. × 50% RH with respect to the polarizing plate of the pressure-sensitive adhesive layer used in the pressure-sensitive adhesive sheet is 0.25 N / It is preferably 25 mm or less, more preferably 0.01 to 0.2 N / 25 mm, and still more preferably 0.03 to 0.15 N / 25 mm. If the peel adhesive strength (tensile speed: 0.3 m / min) is less than 0.01 N / 25 mm, it may be easily peeled off other than the peeling step, which is not preferable. On the other hand, if it exceeds 0.25 N / 25 mm, the peeling workability when it becomes unnecessary is not preferable.

Moreover, it is preferable that 180 degree peel adhesive force (tensile speed of 30 m / min) at 23 degreeC x 50% RH with respect to a polarizing plate is 3.0 N / 25mm or less, and is 0.1-2.5 N / 25mm. It is more preferable, and it is especially preferable that it is 0.2-2.0N / 25mm. If the peel adhesive strength (tensile speed 30 m / min) is less than 0.1 N / 25 mm, it may be easily peeled off other than the peeling step, which is not preferable. On the other hand, if it exceeds 3.0 N / 25 mm, the peeling workability when it becomes unnecessary is inferior, and the adherend may be damaged by the peeling work, which is not preferable.

  Further, when the pressure-sensitive adhesive sheet of the present invention is used as a surface protective film, the pressure-sensitive adhesive layer is preferably formed on one side or both sides of a support film, and the support film is further subjected to antistatic treatment. It is preferable that it is a plastic film. Use of the support film is preferable because charging of the surface protective film itself when peeled can be suppressed. In addition, since it has a pressure-sensitive adhesive layer formed by cross-linking the pressure-sensitive adhesive composition having the above-described effects, it is possible to prevent static charge on a non-static object to be protected when peeled off, and to contaminate the protected object. Is a surface protective film with a reduced content. For this reason, it becomes very useful as an antistatic surface protective film in a technical field related to optical and electronic components in which charging and contamination are particularly serious problems. In addition, the support film is a plastic film, and by applying an antistatic treatment to the plastic film, it is possible to reduce the charge of the surface protective film itself and to have an excellent antistatic ability to an object to be protected.

  The support film is more preferably a plastic film having heat resistance and solvent resistance and having 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 the present invention, the antistatic treatment applied to the plastic film is not particularly limited, but a method of providing an antistatic layer on at least one side of a commonly used substrate or a kneading type antistatic agent in a plastic film is used. A kneading method is used. As a method of providing an antistatic layer on at least one surface of a base material, a method of applying an antistatic resin or a conductive polymer composed of an antistatic agent and a resin component, a conductive resin containing a conductive substance, or a conductive substance is used. Examples of the method include vapor deposition or plating.

  Antistatic agents contained in the antistatic resin include cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, primary, secondary and tertiary amino groups, and sulfonic acids Anionic antistatic agents having an anionic functional group such as salts, sulfate esters, phosphonates and phosphate esters, alkylbetaines and derivatives thereof, imidazolines and derivatives thereof, and amphoteric antistatic agents such as alanine and derivatives thereof Nonionic antistatic agents such as amino alcohol and derivatives thereof, glycerin and derivatives thereof, polyethylene glycol and derivatives thereof, and monomers having cationic conductive, anionic and zwitterionic ion conductive groups. Examples thereof include ionic conductive polymers obtained by polymerization. These compounds may be used alone or in combination of two or more.

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

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

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

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

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

  Examples of the conductive material include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, 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 and drying this coating liquid on a plastic film. Is done.

  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. If it is in the range of the previous period, the possibility of impairing the heat resistance, solvent resistance, and flexibility of the plastic film is small, which is preferable.

  Further, as the kneading type antistatic agent, the above antistatic agent is appropriately used. The amount of the kneading type antistatic agent is 20% by weight or less, preferably 0.05 to 10% by weight, based on the total weight of the plastic 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.

  In the pressure-sensitive adhesive sheet or surface protective film of the present invention, a separator can be bonded to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface as necessary.

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

  The thickness of the separator is usually about 5 to 200 μm, preferably about 10 to 100 μm. 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 perform antistatic treatment such as.

  The surface protective film of the present invention has a 180 ° peel adhesive force (pull rate of 0.3 m / min) at 23 ° C. × 50% RH with respect to the polarizing plate of the pressure-sensitive adhesive layer used in the surface protective film is 0.25 N / min. It is preferably 25 mm or less, more preferably 0.01 to 0.2 N / 25 mm, and still more preferably 0.03 to 0.15 N / 25 mm. When the peel adhesive strength (tensile speed: 0.3 m / min) is less than 0.01 N / 25 mm, the protective tape is easily peeled off from the adherend except during the peeling step, and the protective function for the adherend is impaired. This is not preferable. On the other hand, if it exceeds 0.25 N / 25 mm, the protective tape is difficult to peel off from the adherend, and the workability of peeling when the protective tape is no longer necessary is inferior.

  Moreover, it is preferable that 180 degree peel adhesive force (tensile speed of 30 m / min) at 23 degreeC x 50% RH with respect to a polarizing plate is 3.0 N / 25mm or less, and is 0.1-2.5 N / 25mm. It is more preferable, and it is especially preferable that it is 0.2-2.0N / 25mm. When the peel adhesive strength (tensile speed 30 m / min) is less than 0.1 N / 25 mm, the protective tape is easily peeled off from the adherend other than during the peeling step, and the protective function for the adherend is impaired. It is not preferable. On the other hand, if it exceeds 3.0 N / 25 mm, the protective tape is difficult to peel off from the adherend, and the peelability when the protective tape is no longer necessary is inferior. Further, the adherend is damaged by the peeling process. Therefore, it is not preferable.

  The pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive sheet (including a surface protective film) using the present invention are used particularly for plastic products and the like that are likely to generate static electricity. For this reason, in the technical field related to optical and electronic parts where charging becomes a particularly serious problem, it is very useful for preventing charging.

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

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

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

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

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

Sample concentration: 0.2% by weight (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)
In addition, the weight part average molecular weight was calculated | required in the polystyrene conversion value.

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

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

  In addition, as a reference value, “Synthesis / design of acrylic resin and development of new applications” (published by Central Management Development Center Publishing Department) was referred.

<Measurement of glass transition temperature>
The glass transition temperature (Tg) (° C.) was determined by the following method using a dynamic viscoelasticity measuring apparatus (ARES, manufactured by Rheometrics).

  A sheet of (meth) acrylic polymer (thickness: 20 μm) was laminated to a thickness of about 2 mm, and this was punched out to φ7.9 mm to produce a cylindrical pellet to obtain a glass transition temperature measurement sample.

  The measurement sample is fixed to a jig of 7.9 mm parallel plate, the temperature dependence of the loss elastic modulus G ″ is measured by the dynamic viscoelasticity measuring device, and the obtained G ″ curve is maximized. The temperature was the glass transition temperature (° C.).

The measurement conditions are as follows.
・ Measurement: Shear mode ・ Temperature range: −70 ° C. to 150 ° C.
・ Raising rate: 5 ° C / min
-Frequency: 1 Hz.

<Measurement of peeling voltage>
The adhesive sheet is cut to a size of 70 mm in width and 130 mm in length, the separator is peeled off, and then attached to an acrylic plate (thickness: 2 mm, width: 70 mm, length: 100 mm) previously neutralized. Alternatively, it was pressure-bonded with a hand roller so that one end of the AG polarizing plate (manufactured by Nitto Denko Corporation, SEG1425DU polarizing plate, AGS1 polarizing plate, width: 70 mm, length: 100 mm) protrudes 30 mm.

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

<Evaluation of contamination>
The prepared pressure-sensitive adhesive sheet was cut into a size of 50 mm in width and 80 mm in length, the separator was peeled off, and then the TAC polarizing plate or AG polarizing plate cut into a width of 70 mm and a length of 100 mm (manufactured by Nitto Denko Corporation, SEG1425DU polarizing plate, An AGS1 polarizing plate (width: 70 mm, length: 100 mm) was laminated at a pressure of 0.25 MPa and a speed of 0.3 m / min to prepare an evaluation sample.

  After leaving the evaluation sample at 23 ° C. × 50% RH for one day, the adhesive sheet is peeled off from the adherend by hand, and the contamination state of the adherend surface at that time is compared with the adherend to which the evaluation sample is not attached. However, it was observed visually. The evaluation criteria are as follows. If no contamination was found: ○ If contamination was found: ×

<Measurement of adhesive strength>
A TAC polarizing plate or an AGS1 polarizing plate (manufactured by Nitto Denko Corp., SEG1425DU polarizing plate, AGS1 polarizing plate width: 70 mm, length: 100 mm) was allowed to stand in an environment of 23 ° C. × 50% RH for 24 hours, and then a width of 25 mm, a length A pressure-sensitive adhesive sheet cut to a thickness of 100 mm was laminated on the adherend at a pressure of 0.25 MPa and a speed of 0.3 m / min to prepare an evaluation sample.

  After laminating, after leaving for 30 minutes in an environment of 23 ° C. × 50% RH, when peeling at a peeling speed of 0.3 m / min or peeling speed of 30 m / min and a peeling angle of 180 ° with a universal tensile testing machine. The adhesive strength of was measured. The measurement was performed in an environment of 23 ° C. × 50% RH.

<Preparation of (meth) acrylic polymer>
[Acrylic polymer (A)]
200 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, and 2,2′-azobisiso as a polymerization initiator in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser Acrylic polymer was prepared by adding 0.4 parts by weight of butyronitrile and 312 parts by weight of ethyl acetate, introducing nitrogen gas with gentle stirring, and maintaining the liquid temperature in the flask at around 65 ° C. for 6 hours. (A) A solution (40% by weight) was prepared. The acrylic polymer (A) had a weight average molecular weight of 540,000, a glass transition temperature (Tg) theoretical value of −68 ° C., an actual measurement value of −55 ° C., and an acid value of 0.0.

[Acrylic polymer (B)]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, a cooler, and a dropping funnel, 199 parts by weight of 2-ethylhexyl acrylate, 1 weight of reactive surfactant (manufactured by Kao Corporation, LATEMUL PD-420) Part, 2-hydroxyethyl acrylate 8 parts by weight, 2,2′-azobisisobutyronitrile 0.4 part by weight as a polymerization initiator, and 312 parts by weight ethyl acetate are introduced, and nitrogen gas is introduced while gently stirring. Then, a polymerization reaction was carried out for 6 hours while maintaining the liquid temperature in the flask at around 65 ° C. to prepare an acrylic polymer (B) solution (40% by weight). The acrylic polymer (B) had a weight average molecular weight of 410,000, a measured value of glass transition temperature (Tg) of −53 ° C., and an acid value of 0.0.

[Acrylic polymer (C)]
200 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of acrylic acid, and 2,2′-azobisisobutyronitrile as a polymerization initiator in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser 0.4 parts by weight and 312 parts by weight of ethyl acetate were charged, nitrogen gas was introduced with gentle stirring, and the polymerization temperature was kept at around 65 ° C. for 6 hours to carry out an acrylic polymer (C). A solution (40% by weight) was prepared. The acrylic polymer (C) had a weight average molecular weight of 540,000, a theoretical value of glass transition temperature (Tg) of −66 ° C., an actually measured value of −60 ° C., and an acid value of 29.5.

<Preparation of antistatic agent solution>
[Antistatic agent solution (a)]
15 parts by weight of lithium perchlorate (manufactured by Nacalai Tesque) in a four-necked flask equipped with a stirring blade, a thermometer and a condenser, organopolysiloxane having a polyoxyalkylene side chain (KF-353, manufactured by Shin-Etsu Chemical Co., Ltd.) The HLB value is 10) 35 parts by weight and 200 parts by weight of ethyl acetate are charged, and the mixture is stirred for 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to prepare an antistatic agent solution (a) (20% by weight). did.

[Antistatic agent solution (b)]
15 parts by weight of lithium perchlorate (manufactured by Nacalai Tesque) in a four-necked flask equipped with a stirring blade, a thermometer and a condenser, organopolysiloxane having a polyoxyalkylene side chain (KF-6011, manufactured by Shin-Etsu Chemical Co., Ltd.) The HLB value was 12) 35 parts by weight and 200 parts by weight of ethyl acetate were added, and the mixture was stirred for 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to prepare an antistatic agent solution (b) (20% by weight). did.

[Antistatic agent solution (c)]
Organopolysiloxane (KF-353 manufactured by Shin-Etsu Chemical Co., Ltd.) having 15 parts by weight of lithium trifluoromethanesulfonate (manufactured by Kishida Chemical Co., Ltd.) and a polyoxyalkylene side chain in a four-necked flask equipped with a stirring blade, a thermometer and a condenser The HLB value was 10) 35 parts by weight and 200 parts by weight of ethyl acetate were charged. The mixture was stirred for 2 hours while keeping the liquid temperature in the flask at around 80 ° C., and the antistatic agent solution (c) (20% by weight) was added. Prepared.

[Antistatic agent solution (d)]
10 parts by weight of lithium perchlorate (manufactured by Nacalai Tesque) in a four-necked flask equipped with a stirring blade, a thermometer, and a condenser, organopolysiloxane having a polyoxyalkylene side chain (KF-353 manufactured by Shin-Etsu Chemical Co., Ltd.) The HLB value is 10) 40 parts by weight and 200 parts by weight of ethyl acetate are added, and the mixture is stirred for 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to prepare an antistatic agent solution (d) (20% by weight). did.

[Antistatic agent solution (e)]
Organopolysiloxane (KF-353, Shin-Etsu Chemical Co., Ltd.) having 25 parts by weight of lithium perchlorate (manufactured by Nacalai Tesque) and polyoxyalkylene side chain in a four-necked flask equipped with a stirring blade, a thermometer, and a condenser 25 parts by weight and 200 parts by weight of ethyl acetate were charged, and the mixture was stirred for 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to prepare an antistatic agent solution (e) (20% by weight).

[Antistatic agent solution (f)]
15 parts by weight of lithium perchlorate (manufactured by Nacalai Tesque), 35 parts by weight of polyethylene glycol (diol-terminated type, molecular weight 2000) (manufactured by Wako Pure Chemical Industries, Ltd.) in a four-necked flask equipped with a stirring blade, a thermometer and a condenser Then, 200 parts by weight of methanol was charged, and the mixture was stirred for 2 hours while maintaining the liquid temperature in the flask at around 50 ° C. to prepare an antistatic agent solution (f) (20% by weight).

<Example 1>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted with ethyl acetate to 20% by weight, and 0.05 parts by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (1) was prepared. In the acrylic pressure-sensitive adhesive solution (1), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.075 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.175 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.25 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

[Preparation of adhesive sheet]
The acrylic pressure-sensitive adhesive solution (1) was applied to the surface opposite to the antistatic surface of an antistatic polyethylene terephthalate film (Mitsubishi Resin, T100G38), heated at 130 ° C. for 2 minutes, A 15 μm pressure-sensitive adhesive layer was formed. Next, a silicone-treated surface of a polyethylene terephthalate film (thickness 25 μm) having a silicone treatment on one side was bonded to the surface of the pressure-sensitive adhesive layer to produce a pressure-sensitive adhesive sheet.

<Example 2>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (2) was prepared. In the acrylic pressure-sensitive adhesive solution (2), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.15 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.35 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.5 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

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

<Example 3>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.20 part by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (3) was prepared. In the acrylic pressure-sensitive adhesive solution (3), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.3 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.7 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 1.0 part by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

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

<Example 4>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted with ethyl acetate to 20% by weight, and the antistatic agent solution (a) (20% by weight) 0.60 part by weight is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (4) was prepared. In the acrylic pressure-sensitive adhesive solution (4), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.9 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 2.1 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 3.0 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

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

<Example 5>
(Preparation of adhesive solution)
The acrylic polymer (B) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (5) was prepared. In the acrylic pressure-sensitive adhesive solution (5), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.15 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.35 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.5 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

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

<Example 6>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (b) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (6) was prepared. In the acrylic pressure-sensitive adhesive solution (6), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.15 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.35 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.5 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

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

<Example 7>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (c) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (7) was prepared. In the acrylic pressure-sensitive adhesive solution (7), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.15 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.35 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.5 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

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

<Example 8>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (d) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (8) was prepared. In the acrylic pressure-sensitive adhesive solution (8), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.1 part by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.4 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.5 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 20:80.

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

<Example 9>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (e) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX, 100% by weight) as an agent, and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst The mixture was stirred and an acrylic pressure-sensitive adhesive solution (9) was prepared. In the acrylic pressure-sensitive adhesive solution (9), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.25 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.25 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.5 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 50:50.

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

<Comparative Example 1>
(Preparation of adhesive solution)
An acrylic pressure-sensitive adhesive solution (10) was prepared in the same manner as in Example 1 except that the antistatic agent solution (a) was not used.

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

<Comparative example 2>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (f) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) as an agent and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst Acrylic pressure-sensitive adhesive solution (11) was prepared. In addition, in the acrylic adhesive solution (11), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.15 parts by weight. The blending amount of polyethylene glycol with respect to 100 parts by weight of the acrylic polymer was 0.35 parts by weight. The total amount of alkali metal salt (lithium salt) and polyethylene glycol was 0.5 part by weight. The weight ratio of alkali metal salt (lithium salt) to polyethylene glycol was 30:70.

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

<Comparative Example 3>
(Preparation of adhesive solution)
The acrylic polymer (C) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.1 part by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 1,4-bis (NN-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, TETRAD-C) as an agent, isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) 0.12 parts by weight and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst were added and mixed and stirred to prepare an acrylic pressure-sensitive adhesive solution (12). In the acrylic pressure-sensitive adhesive solution (12), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.15 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.35 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.5 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (12) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Comparative Example 4>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and 0.02 part by weight of the antistatic agent solution (a) (20% by weight) is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) as an agent and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst Acrylic pressure-sensitive adhesive solution (13) was prepared. In the acrylic pressure-sensitive adhesive solution (13), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 0.03 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 0.07 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 0.1 part by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (13) was used instead of the acrylic pressure-sensitive adhesive solution (1).

<Comparative Example 5>
(Preparation of adhesive solution)
The acrylic polymer (A) solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and the antistatic agent solution (a) (20% by weight) 5.0 parts by weight is added to 100 parts by weight of this solution. 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) as an agent and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst Acrylic pressure-sensitive adhesive solution (14) was prepared. In the acrylic pressure-sensitive adhesive solution (14), the blending amount of the alkali metal salt (lithium salt) with respect to 100 parts by weight of the acrylic polymer was 1.5 parts by weight. The compounding amount of the organopolysiloxane having a polyoxyalkylene side chain with respect to 100 parts by weight of the acrylic polymer was 3.5 parts by weight. The total amount of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 5.0 parts by weight. The weight ratio of the alkali metal salt (lithium salt) and the organopolysiloxane having a polyoxyalkylene side chain was 30:70.

[Preparation of adhesive sheet]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (14) was used in place of the acrylic pressure-sensitive adhesive solution (1).

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

  From the results of Table 1 above, when the pressure-sensitive adhesive composition containing the polyoxyalkylene side chain produced by the present invention and an alkali metal salt was used (Examples 1 to 9), Also in the examples, the absolute value of the peeling band voltage of the polarizing plate was suppressed to a low value of 1.0 kV or lower, no contamination was observed, and it was confirmed to have transparency.

  In addition, the adhesive sheets of Examples 1 to 9 of the present invention have a 180 ° peel adhesive strength at a peeling speed of 0.3 m / min in a range of 0.25 N / 25 mm or less, and 180 ° at a peeling speed of 30 m / min. It can be seen that the peel adhesive strength is in a range of 3.0 N / 25 mm or less, and it is an adhesive sheet that can be applied as a re-peelable surface protective film.

  In contrast, when no alkali metal salt and organopolysiloxane having a polyoxyalkylene side chain were contained (Comparative Example 1), the adhesive strength was low and contamination to the polarizing plate was not observed. The absolute value of the voltage was a high value exceeding 1.0 kV. In the case of using polyethylene glycol in place of the organopolysiloxane having a polyoxyalkylene side chain (Comparative Example 2), although the contamination to the polarizing plate was not observed, the adhesive force to the TAC polarizing plate was 3.0 N / The absolute value of the peeling band voltage to the AG polarizing plate was as high as 1.0 kV or more, exceeding 25 mm. When an acrylic polymer having an acid value of 1.0 or more is used (Comparative Example 3), the contamination of the polarizing plate was not observed, but the absolute value of the stripping voltage to the AG polarizing plate was 1.0 kV or more. The adhesive strength to the TAC polarizing plate was a high value exceeding 3.0 N / 25 mm. In the case of using a pressure-sensitive adhesive composition in which an organopolysiloxane having an alkali metal salt and a polyoxyalkylene side chain is blended in an amount of less than 0.15 parts by weight with respect to 100 parts by weight of an acrylic polymer (Comparative Example 4), Although the contamination to the polarizing plate was not recognized, the absolute value of the peeling band voltage was as high as 1.0 kV or more. In the case of using a pressure-sensitive adhesive composition in which an alkali metal salt and an organopolysiloxane having a polyoxyalkylene side chain were blended in an amount exceeding 4 parts by weight with respect to 100 parts by weight of the acrylic polymer (Comparative Example 5), the stripping voltage was Although kept low, contamination to the polarizing plate was observed. Accordingly, in all of the comparative examples, it is impossible to suppress the stripping voltage, suppress the occurrence of contamination on the polarizing plate, and light release properties, and it is suitable for the pressure-sensitive adhesive composition for the antistatic pressure-sensitive adhesive sheet. It became clear that there was no.

Therefore, it can be confirmed that the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition having excellent anti-releasability when peeled and having excellent anti-removability with reduced contamination to the protected body. It was.

Claims (6)

As a monomer component, 2-ethylhexyl acrylate is contained in 19900 / 208-99.9% by weight, and has an (meth) acrylic polymer having an acid value of 1.0 or less, an alkali metal salt, and a polyoxyalkylene side chain. Containing 100 parts by weight of the (meth) acrylic polymer, the total of the alkali metal salt and the organopolysiloxane is 0.15 to 4 parts by weight, and the alkali metal salt and the The content ratio of the organopolysiloxane is a pressure- sensitive adhesive sheet formed by forming a pressure-sensitive adhesive layer formed by crosslinking a pressure-sensitive adhesive composition having a weight ratio of 20:80 to 50:50 on one side or both sides of a support film. ,
Under the condition of 23 ° C. × 50% RH with respect to the polarizing plate surface of the pressure-sensitive adhesive layer, the 180 ° peel adhesive strength at a peeling rate of 0.3 m / min is 0.25 N / 25 mm or less,
A pressure-sensitive adhesive sheet having a 180 ° peel adhesive strength of 3.0 N / 25 mm or less at a peeling speed of 30 m / min under a condition of 23 ° C. × 50% RH. The pressure-sensitive adhesive sheet according to claim 1, wherein the organopolysiloxane is represented by the following formula.

(Wherein R ₁ is a monovalent organic group, R ₂ , R ₃ and R ₄ are alkylene groups, R ₅ is hydrogen or an organic group, m and n are integers from 0 to 1000, provided that m and n are simultaneously (A and b are integers from 0 to 100, provided that a and b are not 0 at the same time.) The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the alkali metal salt is a lithium salt. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the (meth) acrylic polymer further contains a hydroxyl group-containing (meth) acrylic monomer as a monomer component. The said (meth) acrylic-type polymer further contains 5.0 weight% or less of alkylene oxide group containing reactive monomer whose average addition mole number of an oxyalkylene unit is 3-40 as a monomer component. The pressure-sensitive adhesive sheet according to any one of the above. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the support film is a plastic film subjected to an antistatic treatment.

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