JP2017128636A - Adhesive composition and optical member surface protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive composition capable of achieving both antistatic properties and low contamination properties to an adherend at a high level, and an optical member surface protective film using the same.SOLUTION: The adhesive composition contains: a (meth)acrylic polymer having a hydroxy group and an acid value of 0 mg KOH/g or more and less than 16 mg KOH/g; an alkylene oxide chain-containing (meth)acrylic oligomer having an acid value of 0.1 mg KOH/g or more and 40 mg KOH/g or less; a polyether-modified silicone having a reactive group; a crosslinking agent; and an ionic compound.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive composition and an optical member surface protective film.

  In recent years, liquid crystal display devices have been used as screen display devices for various information-related devices such as word processors and notebook personal computers because they are thin and light and consume less power. In such a liquid crystal display device, an optical member such as a polarizing plate and a retardation plate is used together with a glass cell (liquid crystal cell) containing liquid crystal as a main body.

  These optical members are usually further adhesively coated with a surface protection film so that the surface is not contaminated or damaged during each process such as punching, inspection, transportation, and assembly of liquid crystal display devices. And formed as a long optical member laminate. The surface protective film is peeled off from the optical member at the stage where surface protection is no longer necessary.

  While such a surface protective film is required to protect the surface of the optical member, the surface protective film adheres to the surface to such an extent that the optical member does not deviate or fall off from the surface. In order not to interfere with various inspections such as liquid crystal performance inspection, it must be highly transparent, and there should be no defects in the adhesive layer such as bulge, tunneling, peeling, and the interface between the adhesive layer and the optical member. Is required. When peeling the film from the optical member, in order not to damage the optical member and the liquid crystal cell due to the distortion caused by the peeling, and so as not to cause inconvenience such as the optical member peeling from the liquid crystal cell, It must be easily peelable. Furthermore, when the surface protective film is peeled off, it is required that no residue derived from the surface protective film is formed on the optical member, that is, that the adherence to the adherend is low (hereinafter also simply referred to as “low contamination”). .

  On the other hand, when static electricity is generated when the surface protective film is peeled from the optical member, dust or dust is adsorbed on the surface of the optical film, resulting in inconvenience for the product. In addition, when the surface protection film is peeled off, if a large amount of static electricity is generated, the circuit of the display member may be destroyed. Therefore, the surface protective film is required to suppress the generation of static electricity due to peeling and to have good antistatic properties.

  In relation to the above, a pressure-sensitive adhesive containing an acrylic polymer, an alkali metal salt, and a dimethylpolysiloxane compound having a polyoxyethylene group having a hydroxy group at the terminal is disclosed (for example, see Patent Document 1).

JP2013-163745A

However, in recent years, the level of contamination required is improved. For example, in the pressure-sensitive adhesive described in Patent Document 1, it is difficult to achieve both antistatic properties and low contamination on an adherend at a higher level. was there.
This invention makes it a subject to provide the adhesive composition which can make antistatic property and the low pollution property with respect to a to-be-adhered body compatible at a high level, and an optical member surface protection film using the same.

Specific means for solving the above problems are as follows.
<1> (meth) acrylic polymer having a hydroxy group and having an acid value of 0 mgKOH / g or more and less than 16 mgKOH / g, and an alkylene oxide chain containing (meth) having an acid value of 0.1 mgKOH / g or more and 40 mgKOH / g or less A pressure-sensitive adhesive composition comprising an acrylic oligomer, a polyether-modified silicone having a reactive group, a crosslinking agent, and an ionic compound.

<2> 0.1 to 7.0 parts by mass in total of the alkylene oxide chain-containing (meth) acrylic oligomer and the polyether-modified silicone are included with respect to 100 parts by mass of the (meth) acrylic polymer <1> 2. The pressure-sensitive adhesive composition according to 1.

<3> The pressure-sensitive adhesive composition according to <1> or <2>, wherein the acid value of the (meth) acrylic polymer is 2 mgKOH / g or more and 12 mgKOH / g or less.

<4> The pressure-sensitive adhesive composition according to any one of <1> to <3>, wherein the reactive group of the polyether-modified silicone is a hydroxy group, and the crosslinking agent is a polyisocyanate compound.

<5> The pressure-sensitive adhesive composition according to any one of <1> to <4>, which is used for an optical member surface protective film.

<6> An optical member surface protective film comprising: a base material; and a pressure-sensitive adhesive layer provided on the base material and derived from the pressure-sensitive adhesive composition according to any one of <1> to <4>. .

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which can make antistatic property and the low pollution property with respect to a to-be-adhered body compatible on a high level, and an optical member surface protection film using the same can be provided.

In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. Further, in the present specification, when referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, the plurality of the components present in the composition unless otherwise specified. It means the total amount of substance.
Further, “(meth) acrylate” is a term including both acrylate and methacrylate, and “(meth) acryl” is a term including both acrylic and methacrylic.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention has a hydroxy group and has an acid value of 0 mgKOH / g or more and less than 16 mgKOH / g (hereinafter also referred to as “specific (meth) acrylic polymer”), Polyether-modified silicone having an alkylene oxide chain-containing (meth) acrylic oligomer (hereinafter also referred to as “specific (meth) acrylic oligomer”) having an acid value of 0.1 mgKOH / g to 40 mgKOH / g, and a reactive group (Hereinafter also referred to as “specific polysiloxane”), a crosslinking agent, and an ionic compound. The pressure-sensitive adhesive composition may further contain other components as necessary.

  The pressure-sensitive adhesive composition comprises a hydroxy group-containing (meth) acrylic polymer having an acid value of less than 16 mgKOH / g, an alkylene oxide chain-containing (meth) acrylic oligomer having an acid value in a specific range, and a reactive group-containing poly By containing an ether-modified silicone, a cross-linking agent, and an ionic compound, both the antistatic property and the low contamination property to the adherend are excellent, and the adhesiveness is also excellent. Such an adhesive composition can be preferably applied to an optical member surface protective film.

For example, this can be considered as follows.
The pressure-sensitive adhesive composition contains a specific (meth) acrylic oligomer having an acid value in a specific range and a specific polysiloxane having a reactive group, so that the (meth) acrylic oligomer can cause contamination of the adherend. The specific polysiloxane reacts with the crosslinking agent, and free (meth) acrylic oligomers and the specific polysiloxane that are not crosslinked are reduced. Furthermore, the specific (meth) acrylic oligomer having a molecular weight smaller than that of the specific (meth) acrylic polymer has an acid value in a specific range, so that the reaction between the specific polysiloxane and the crosslinking agent is promoted by the acid, and the effect is more effective. Free specific polysiloxanes can be reduced. As a result, the optical member surface protective film produced from the pressure-sensitive adhesive composition can be prevented from being contaminated by free specific (meth) acrylic oligomers and specific polysiloxanes that are not crosslinked.
In addition, since the acid value of the specific (meth) acrylic polymer is as small as less than 16 mgKOH / g, and the specific (meth) acrylic oligomer and the specific polysiloxane have a polyalkyleneoxy group, ions derived from the ionic compound are reduced. It is easy to move and can effectively suppress the generation of static electricity due to peeling charging.

[(Meth) acrylic polymer]
The pressure-sensitive adhesive composition of the present invention contains at least one specific (meth) acrylic polymer having a hydroxy group and having an acid value of 0 mgKOH / g or more and less than 16 mgKOH / g. The pressure-sensitive adhesive composition may further contain a (meth) acrylic polymer different from the specific (meth) acrylic polymer as necessary.
Here, the (meth) acrylic polymer is 50% by mass or more, preferably 90% by mass or more of all monomer components constituting the polymer (the monomer constituting the polymer may be simply referred to as a polymer component). ) A polymer that is an acrylic monomer.

  The acid value of the specific (meth) acrylic polymer is 0 mgKOH / g or more and less than 16 mgKOH / g from the viewpoint of suppressing the generation of static electricity due to peeling charging and improving the antistatic property. When the acid value of the (meth) acrylic polymer is as high as 16 mgKOH / g or more, generation of static electricity due to peeling charging cannot be suppressed, and the antistatic property is deteriorated.

The acid value of the specific (meth) acrylic polymer is preferably 12 mgKOH / g or less, and more preferably 7 mgKOH / g or less. If the acid value of the specific (meth) acrylic polymer is 12 mgKOH / g or less, an increase in the viscosity of the coating liquid over time can be suppressed, and a sufficient pot life can be obtained. The subsequent increase in adhesive strength can be suppressed.
The acid value of the specific (meth) acrylic polymer is preferably 2 mgKOH / g or more, and more preferably 4 mgKOH / g or more. If the acid value of the specific (meth) acrylic polymer is 2 mgKOH / g or more, it is possible to obtain a pressure-sensitive adhesive composition having excellent curability, short curing time and fast initial curing speed without using a crosslinking catalyst. it can. When the initial curing rate of the pressure-sensitive adhesive composition is high, in the production of the optical member surface protective sheet, when the sheet is wound into a roll, it is difficult for a trace to remain and the workability is excellent. Furthermore, if the acid value of the specific (meth) acrylic polymer is 2 or more, a (meth) acrylic polymer that does not have a reactive group with a crosslinking agent such as a carboxy group or a hydroxy group is hardly generated during the polymerization. In the optical member surface protective film produced by including this, the (meth) acrylic polymer is less likely to remain on the adherend, and is further excellent in low contamination to the adherend.

  The acid value of the (meth) acrylic polymer or the (meth) acrylic oligomer described later can be determined by the following calculation formulas.

Acid value (mgKOH / g) = {(A / 100) ÷ B} × 56.1 × 1000 × C
A = Content of monomer having carboxy group (% by mass) in all monomers used in (meth) acrylic polymer or (meth) acrylic oligomer
B = molecular weight of monomer having carboxy group used in (meth) acrylic polymer or (meth) acrylic oligomer C = number of carboxy groups contained in one molecule of monomer having carboxy group 56.1 is KOH Is the molecular weight.
Moreover, when there are multiple types of monomers having a carboxy group, the acid value can be obtained by adding together the values obtained from the above formula for each monomer.

  The specific (meth) acrylic polymer includes at least one structural unit derived from a monomer having a hydroxy group. The monomer having a hydroxy group is not particularly limited as long as it is a monomer having at least one hydroxy group and an ethylenically unsaturated bond group, and can be appropriately selected from commonly used monomers.

  Specific examples of the monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 3-methyl. -3-hydroxybutyl (meth) acrylate, 1,1-dimethyl-3-butyl (meth) acrylate, 1,3-dimethyl-3-hydroxybutyl (meth) acrylate, 2,2,4-trimethyl-3-hydroxy Pentyl (meth) acrylate, 2-ethyl-3-hydroxyhexyl (meth) acrylate, glycerin mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, poly (ethylene glycol- (Meth) acrylates such as (propylene glycol) mono (meth) acrylate; (meth) acrylamides such as N-methylol (meth) acrylamide and N-hydroxyethyl (meth) acrylamide; unsaturated such as allyl alcohol and methallyl alcohol Alcohol; and the like.

  Among these, from the point that the compatibility and copolymerization with other monomers are good and the crosslinking reaction with the crosslinking agent is good, it has one hydroxy group and an alkyl group having 2 to 6 carbon atoms ( A (meth) acrylic acid ester is preferable, and 2-hydroxyethyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate is more preferable.

  As a content rate of the structural unit derived from the monomer which has a hydroxyl group in specific (meth) acrylic-type polymer, in the total mass of specific (meth) acrylic-type polymer, 0.1 mass% or more and 10.0 mass% or less It is preferable that it is 2.0 mass% or more and 8.0 mass% or less, and it is still more preferable that it is 2.0 mass% or more and 5.0 mass% or less. There exists a tendency which can suppress more effectively generation | occurrence | production of the contamination with respect to a to-be-adhered body because the content rate of the structural unit derived from the monomer which has a hydroxyl group is more than the said lower limit. Moreover, there exists a tendency for a conformability (wetting property) to become more favorable because it is below the said upper limit.

The specific (meth) acrylic polymer preferably further includes at least one structural unit derived from an alkyl (meth) acrylate in addition to the structural unit derived from a monomer having a hydroxy group.
The alkyl group in the alkyl (meth) acrylate may be linear or branched. 1-18 are preferable and, as for carbon number of the alkyl group in alkyl (meth) acrylate, 2-10 are more preferable from an adhesive viewpoint.

  Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-octyl (meth) acrylate, and isooctyl (meth) acrylate. , 2-ethylhexyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, stearyl (meth) acrylate, etc. Mention may be made of alkyl (meth) acrylates having 18 straight-chain or branched alkyls and their derivatives.

  The specific (meth) acrylic polymer may contain one or more structural units derived from alkyl (meth) acrylate, and preferably contains two or more. When the (meth) acrylic polymer contains two structural units derived from alkyl (meth) acrylate, one is derived from alkyl (meth) acrylate having a linear or branched alkyl group having 1 to 5 carbon atoms. It is preferable that the other is a structural unit derived from an alkyl (meth) acrylate having a linear or branched alkyl group having 6 to 18 carbon atoms, one of which is 2 to 5 carbon atoms. Is a structural unit derived from an alkyl (meth) acrylate having a linear alkyl group, and the other is a structural unit derived from an alkyl (meth) acrylate having a branched alkyl group having 6 to 10 carbon atoms. More preferably.

  Especially, as a structural unit derived from alkyl (meth) acrylate, it is preferable to contain at least one of butyl acrylate and 2-ethylhexyl acrylate, and it is more preferable to contain both.

  When the specific (meth) acrylic polymer includes a structural unit derived from alkyl (meth) acrylate, the content is 60% by mass or more and 99.9% by mass or less in the total mass of the specific (meth) acrylic polymer. It is preferable that it is 72 mass% or more and 99.5 mass% or less, and it is still more preferable that it is 85 mass% or more and 99 mass% or less. When the content of the structural unit derived from the alkyl (meth) acrylate is equal to or more than the lower limit value, the conformability (wetting property) tends to become better. Moreover, when the content rate of the structural unit derived from the alkyl (meth) acrylate is not more than the above upper limit value, the adhesive force at the time of high-speed peeling does not become too large, and the workability at the time of high-speed peeling tends to be more excellent.

  The specific (meth) acrylic polymer further includes at least one structural unit derived from a monomer having a carboxy group, in addition to a structural unit derived from a monomer having a hydroxy group and a structural unit derived from an alkyl (meth) acrylate. It is preferable to include. The monomer having a carboxy group is not particularly limited as long as it is a monomer having at least one carboxy group and an ethylenically unsaturated bond group, and can be appropriately selected from commonly used monomers.

  Specific examples of the monomer having a carboxy group include (meth) acrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, succinic acid monohydroxyethyl (meth) acrylate, maleic acid Acid monohydroxyethyl (meth) acrylate, fumarate monohydroxyethyl (meth) acrylate, phthalate monohydroxyethyl (meth) acrylate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate, (meth) acrylic acid dimer , Ω-carboxy-polycaprolactone mono (meth) acrylate and the like.

  Among these, (meth) acrylic acid and (meth) acrylic acid ester having a carboxy group are preferable from the viewpoint of good compatibility with other monomers and copolymerization, and (meth) acrylic acid, ω-carboxy-poly Caprolactone mono (meth) acrylate is more preferred.

  When the specific (meth) acrylic polymer includes a structural unit derived from a monomer having a carboxy group, the content is not particularly limited as long as the acid value of the (meth) acrylic polymer is less than 16 mgKOH / g.

  The specific (meth) acrylic polymer, if necessary, other than the structural unit derived from the monomer having a hydroxy group, the structural unit derived from an alkyl (meth) acrylate, and the structural unit derived from a monomer having a carboxy group A structural unit may be further included.

  Specific examples of monomers that form other structural units include (meth) acrylates having cyclic groups such as cyclohexyl (meth) acrylate and benzyl (meth) acrylate; saturated fatty acid vinyl esters such as vinyl formate, vinyl acetate, and propion. Aliphatic vinyl monomers such as vinyl acid and “vinyl versatate” (trade name, vinyl neodecanoate); aromatic vinyl monomers such as styrene, α-methylstyrene and vinyltoluene; cyanovinyl monomers such as acrylonitrile and methacrylonitrile; Dimethyl malate, di-n-butyl malate, di-2-ethylhexyl malate, di-n-octyl malate, dimethyl fumarate, di-n-butyl fumarate, di-2-ethylhexyl fumarate, di-n- Maleic acid such as octyl fumarate Properly diesters monomers fumarate; and the like.

  Furthermore, as another monomer that forms a structural unit, a monomer that has at least one functional group in addition to one ethylenically unsaturated bond group in the molecule and that forms a structural unit having a hydroxy group And a monomer different from the monomer forming the structural unit having a carboxy group (hereinafter also referred to as “functional monomer”). Examples of the functional monomer include monomers having a functional group such as an amide group, a substituted or unsubstituted amide group, a substituted or unsubstituted amino group, an alkoxy group, an epoxy group, a mercapto group, and a silicon-containing group. Moreover, the monomer which has 2 or more of ethylenically unsaturated bond groups in a molecule | numerator can also be used.

  When the specific (meth) acrylic polymer contains other structural units, the content is preferably 30% by mass or less, and 20% by mass or less in the total mass of the specific (meth) acrylic polymer. More preferred is 10% by mass or less. If the content of other structural units is less than or equal to the above upper limit value, the adhesive force at low speed peeling tends to be sufficiently high and the adhesive strength at high speed peeling does not tend to increase. Can be made better.

  The weight average molecular weight of the specific (meth) acrylic polymer is not particularly limited. The weight average molecular weight (Mw) of the specific (meth) acrylic polymer is preferably 200,000 to 1,000,000, more preferably 300,000 to 800,000. If the weight average molecular weight (Mw) of a specific (meth) acrylic-type polymer is more than the said lower limit, there exists a tendency which can suppress generation | occurrence | production of the contamination with respect to a to-be-adhered body more effectively. Moreover, if it is below the said upper limit, there exists a tendency for a conformability (wetting property) to become more favorable.

  Further, the dispersity (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the specific (meth) acrylic polymer, is preferably 20 or less, more preferably 15 or less, and 3 or more and 10 The following is more preferable. If the value of the degree of dispersion (Mw / Mn) is less than or equal to the upper limit value, the occurrence of contamination on the adherend tends to be more effectively suppressed.

  In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of a (meth) acrylic-type polymer or the (meth) acrylic-type oligomer mentioned later are the values measured by the following method.

Method for measuring average molecular weight (Mw and Mn):
It measures according to following (1)-(3).
(1) A solution of (meth) acrylic polymer or (meth) acrylic oligomer is applied to a release paper and dried at 100 ° C. for 2 minutes to form a film-like (meth) acrylic polymer or (meth) acrylic oligomer. obtain.
(2) Using the film-like (meth) acrylic polymer or (meth) acrylic oligomer obtained in (1) above and tetrahydrofuran, a sample solution having a solid content concentration of 0.2% by mass is obtained.
(3) Under the following conditions, using gel permeation chromatography (GPC), the weight average molecular weight (Mw) and number average molecular weight of (meth) acrylic polymer or (meth) acrylic oligomer as standard polystyrene conversion values (Mn) is measured.

(conditions)
GPC: HLC-8220 GPC [manufactured by Tosoh Corporation]
Column: 4 TSK-GEL GMHXL used Mobile phase solvent: Tetrahydrofuran Flow rate: 0.6 mL / min Column temperature: 40 ° C

The content of the specific (meth) acrylic polymer in the pressure-sensitive adhesive composition of the present invention can be appropriately selected according to the purpose and the like. The content of the specific (meth) acrylic polymer is preferably 80% by mass or more and 99% by mass or less, and preferably 85% by mass or more and 99% by mass or less in the total solid content of the pressure-sensitive adhesive composition. More preferably, it is 90 mass% or more and 98 mass% or less.
In addition, solid content gross mass means the gross mass of the residue remove | excluding volatile components, such as a solvent, from an adhesive composition.

[(Meth) acrylic oligomer]
The pressure-sensitive adhesive composition of the present invention further contains at least one specific (meth) acrylic oligomer containing a structural unit having a polyalkyleneoxy group and having an acid value of 0.1 mgKOH / g or more and 40 mgKOH / g or less. . When the pressure-sensitive adhesive composition contains the specific (meth) acrylic oligomer in addition to the specific (meth) acrylic polymer, it is possible to achieve more excellent antistatic properties and low contamination to the adherend.

The specific (meth) acrylic oligomer includes a structural unit having a polyalkyleneoxy group and has a molecular weight smaller than that of the specific (meth) acrylic polymer, and therefore can move relatively easily in the pressure-sensitive adhesive composition. Conceivable. Thereby, it is thought that the surface resistance value of an adhesive composition falls more effectively and can achieve the more superior antistatic property.
Moreover, since a specific (meth) acrylic-type oligomer has an acid value, it is thought that it can react with the crosslinking agent mentioned later. Moreover, since the specific (meth) acrylic oligomer has a molecular weight smaller than that of the specific (meth) acrylic polymer and has an acid value, it is considered that the reaction between the specific polysiloxane described later and the crosslinking agent can be promoted. By these, it is thought that the low pollution property with respect to a to-be-adhered body can be improved more.

The acid value of the specific (meth) acrylic oligomer is from 0.1 mgKOH / g to 40 mgKOH / g from the viewpoint of suppressing the occurrence of contamination on the adherend and improving the antistatic property.
When the acid value of the specific (meth) acrylic oligomer exceeds 40 mgKOH / g, the pressure-sensitive adhesive layer becomes hard due to aging, and the antistatic property decreases with time. Further, when the acid value of the specific (meth) acrylic oligomer is less than 0.1 mgKOH / g, the reaction between the specific (meth) acrylic oligomer and the crosslinking agent or the reaction promoting effect between the specific polysiloxane and the crosslinking agent is achieved. This is not sufficient, and the occurrence of contamination on the adherend cannot be suppressed, and the low contamination on the adherend deteriorates.

  The acid value of the specific (meth) acrylic oligomer is preferably 1 mgKOH / g or more and 20 mgKOH / g or less, and preferably 2 mgKOH / g or more and 10 mgKOH / g or less from the viewpoint of low contamination to the adherend and antistatic property over time. More preferred.

  The specific (meth) acrylic oligomer includes at least one structural unit having a polyalkyleneoxy group. The polyalkyleneoxy group in the (meth) acrylic oligomer preferably includes an alkyleneoxy group having 2 to 4 carbon atoms as a structural unit, and more preferably includes an alkyleneoxy group having 2 to 3 carbon atoms as a structural unit. .

  The number of alkyleneoxy groups contained in the polyalkyleneoxy group can be appropriately selected according to the purpose and the like. The number of alkyleneoxy groups is preferably 20 or more, more preferably 20 to 100, and still more preferably 20 to 50, from the viewpoint of antistatic properties. When the content of the alkyleneoxy group is 20 or more, a more remarkable antistatic property can be exhibited by a combination with an ionic compound described later. In addition, the content number of an alkyleneoxy group becomes a rational number which is an average value of the content number when two or more structural units having an alkyleneoxy group are included in the (meth) acrylic oligomer.

  The terminal portion of the polyalkyleneoxy group may be a hydroxy group or an alkoxy group, and is preferably an alkoxy group from the viewpoint of antistatic properties. When the terminal part of the polyalkyleneoxy group is an alkoxy group, the alkoxy group preferably has 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms.

  The structural unit having a polyalkyleneoxy group may be derived from a monomer having a polyalkyleneoxy group and an ethylenically unsaturated bond group, but the structural unit having no polyalkyleneoxy group may be converted into a polyalkylene by a polymer reaction. An oxy group introduced may be used. From the viewpoint of productivity, the structural unit having a polyalkyleneoxy group is preferably derived from a monomer having a polyalkyleneoxy group and an ethylenically unsaturated bond group.

  Specific examples of the monomer having a polyalkyleneoxy group and an ethylenically unsaturated bond group include polyethylene glycol (meth) acrylate, methoxypolyethyleneoxy (meth) acrylate, ethoxypolyethyleneoxy (meth) acrylate, polypropylene glycol (meth) acrylate, Examples thereof include methoxy polypropyleneoxy (meth) acrylate and ethoxy polypropyleneoxy (meth) acrylate. Among them, at least one selected from the group consisting of methoxypolyethyleneoxy (meth) acrylate and methoxypolypropyleneoxy (meth) acrylate is preferable, and methoxypolyethyleneoxy (meth) acrylate and propyleneoxy group having an ethyleneoxy group content of 20 or more. More preferred is at least one selected from the group consisting of methoxypolypropyloxyoxy (meth) acrylates having a content of 20 or more.

  The specific (meth) acrylic oligomer may contain one or more structural units having a polyalkyleneoxy group alone or in combination of two or more.

  The content of the structural unit having a polyalkyleneoxy group in the specific (meth) acrylic oligomer is from 1% by mass to 50% by mass in the total mass of the specific (meth) acrylic oligomer from the viewpoint of antistatic properties. It is preferably 1% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less.

  The specific (meth) acrylic oligomer includes at least one structural unit derived from a monomer having a carboxy group in addition to the structural unit having a polyalkyleneoxy group. Examples of the structural unit derived from the monomer having a carboxy group include the same structural units derived from the monomer having a carboxy group in the specific (meth) alkyl polymer, and preferred embodiments are also the same.

  The content of the structural unit derived from the monomer having a carboxy group in the specific (meth) acrylic oligomer is particularly limited as long as the acid value of the specific (meth) acrylic oligomer is 0.1 mgKOH / g or more and 40 mgKOH / g or less. Not.

  The specific (meth) acrylic oligomer may contain at least one structural unit derived from an alkyl (meth) acrylate in addition to a structural unit having a polyalkyleneoxy group and a structural unit derived from a monomer having a carboxy group. preferable. Examples of the structural unit derived from the alkyl (meth) acrylate include the same structural units derived from the alkyl (meth) acrylate in the specific (meth) alkyl polymer, and preferred embodiments are also the same.

  When the specific (meth) acrylic oligomer includes a structural unit derived from alkyl (meth) acrylate, the content of the structural unit derived from alkyl (meth) acrylate is in the total mass of the specific (meth) acrylic oligomer. It is preferably 40% by mass to 95% by mass, more preferably 70% by mass to 90% by mass, and still more preferably 80% by mass to 90% by mass. There exists a tendency which can suppress generation | occurrence | production of the contamination with respect to a to-be-adhered body more effectively as the content rate of the structural unit derived from an alkyl (meth) acrylate is more than the said lower limit. Moreover, if the content rate of the structural unit derived from alkyl (meth) acrylate is below the said upper limit, the surface resistance of an adhesive composition will fall and there exists a tendency which can obtain the more superior antistatic property. .

  The specific (meth) acrylic oligomer may contain other structural units other than the structural unit having a polyalkyleneoxy group, the structural unit derived from a monomer having a carboxy group, and the structural unit derived from an alkyl (meth) acrylate as necessary. May be included. Examples of other structural units include the structural units derived from the monomer having a hydroxy group in the specific (meth) alkyl polymer and those similar to other structural units, and preferred embodiments are also the same.

  The molecular weight of the specific (meth) acrylic oligomer is not particularly limited as long as it is smaller than the specific (meth) acrylic polymer. The weight average molecular weight (Mw) of the specific (meth) acrylic oligomer is preferably from 3,000 to 100,000, more preferably from 5,000 to 60,000, still more preferably from 5,000 to 20,000. . There exists a tendency which can suppress more effectively generation | occurrence | production of the contamination with respect to a to-be-adhered body as the weight average molecular weight (Mw) of a specific (meth) acrylic-type oligomer is more than the said lower limit. Moreover, there exists a tendency for antistatic property to improve that it is below the said upper limit.

  Further, the ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the specific (meth) acrylic oligomer is preferably 10 or less, more preferably 7 or less, and still more preferably 1 or more and 5 or less. . If the value of Mw / Mn is less than or equal to the upper limit, there is a tendency that the occurrence of contamination on the adherend tends to be more effectively suppressed. In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of a (meth) acrylic-type oligomer are measured by the method similar to the case of a (meth) acrylic-type polymer.

  The ratio of the weight average molecular weight of the specific (meth) acrylic oligomer to the specific (meth) acrylic polymer (oligomer Mw / polymer Mw) is not particularly limited as long as it is less than 1. From the viewpoint of antistatic properties, the ratio of the weight average molecular weight is preferably 0.1 or less, and more preferably 0.006 to 0.07.

  The content of the specific (meth) acrylic oligomer in the pressure-sensitive adhesive composition of the present invention can be appropriately selected depending on the purpose and the like. The content of the specific (meth) acrylic oligomer is preferably 0.05 parts by mass or more and 5.0 parts by mass or less, and 0.1 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic polymer. It is more preferably 3.0 parts by mass or less, and further preferably 0.2 parts by mass or more and 2.0 parts by mass or less. If the content of the specific (meth) acrylic oligomer is 0.05 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic polymer, better antistatic properties tend to be obtained. Moreover, if content of a specific (meth) acrylic-type oligomer is 5.0 mass parts or less with respect to 100 mass parts of specific (meth) acrylic-type polymers, it can suppress the contamination with respect to a adherend more effectively. There is a tendency to be able to.

  Specific (meth) acrylic polymers and specific (meth) acrylic oligomers (hereinafter, these may be collectively referred to as “polymers”) are a mixture of monomers that can form the structural units contained in these polymers. It can be produced by polymerization. The polymerization method of the polymer is not particularly limited, and can be appropriately selected from known methods such as a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method. In producing the pressure-sensitive adhesive composition of the present invention using the polymer obtained by polymerization, the solution polymerization method is preferred because the treatment process is relatively simple and can be performed in a short time.

  In the solution polymerization method, generally, a predetermined organic solvent, a monomer, a polymerization initiator, and a chain transfer agent to be used as necessary are charged in a polymerization tank, and are stirred at a reflux temperature of the organic solvent in a nitrogen stream. A known method such as performing the reaction by heating for a period of time can be used.

  In addition, the weight average molecular weight and dispersion degree of a specific (meth) acrylic-type polymer and a specific (meth) acrylic-type oligomer can be easily adjusted with reaction temperature, time, the amount of solvents, and the kind and quantity of a catalyst.

  As an organic solvent for polymerization used for the polymerization of the specific (meth) acrylic polymer and the specific (meth) acrylic oligomer, benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m- Aromatic hydrocarbons such as xylene, p-xylene, tetralin, decalin, aromatic naphtha; n-hexane, n-heptane, n-octane, isooctane, n-decane, dipentene, petroleum spirit, petroleum naphtha, terpine oil, etc. Aliphatic or alicyclic hydrocarbons; esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, methyl benzoate, etc. Acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexane Ketones such as non- and methylcyclohexanones; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether; methyl alcohol, ethyl alcohol, n -Alcohols such as propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, s-butyl alcohol, t-butyl alcohol; These organic solvents can be used alone or in combination of two or more.

  As a polymerization initiator, it is possible to use an organic peroxide, an azo compound, etc. which can be used by a normal solution polymerization method. Examples of the organic peroxide include t-butyl hydroperoxide, cumene hydroxide, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, caproyl peroxide, diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxide. Oxydicarbonate, t-butylperoxybivalate, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 2,2-bis (4,4-di-t-amylperoxy) Cyclohexyl) propane, 2,2-bis (4,4-di-t-octylperoxycyclohexyl) propane, 2,2-bis (4,4-di-α-cumylperoxycyclohexyl) propane, 2,2- Bis (4,4-di-t-butylperoxycyclohexyl) butane, , 2-bis (4,4-di -t- octylperoxycarbonyl cyclohexyl) butane. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis-4-methoxy-2,4-dimethyl. Examples include valeronitrile.

  In the production of (meth) acrylic polymers and (meth) acrylic oligomers, it is normal not to use a chain transfer agent, but it is used as necessary within the range that does not impair the purpose and effect of the present invention. It is possible to do. Examples of the chain transfer agent include cyanoacetic acid; alkyl esters having 1 to 8 carbon atoms of cyanoacetic acid; bromoacetic acid; alkyl esters having 1 to 8 carbon atoms of bromoacetic acid; anthracene, phenanthrene, fluorene, 9-phenylfluorene. Aromatic compounds such as p-nitroaniline, nitrobenzene, dinitrobenzene, p-nitrobenzoic acid, p-nitrophenol, p-nitrotoluene, etc .; benzoquinone, 2,3,5,6-tetra Benzoquinone derivatives such as methyl-p-benzoquinone; borane derivatives such as tributylborane; carbon tetrabromide, carbon tetrachloride, 1,1,2,2-tetrabromoethane, tribromoethylene, trichloroethylene, bromotrichloromethane, tri Halogens such as bromomethane and 3-chloro-1-propene Hydrocarbons; Aldehydes such as chloral and furaldehyde: alkyl mercaptans having 1 to 18 carbon atoms; aromatic mercaptans such as thiophenol and toluene mercaptan; alkyl esters having 1 to 10 carbon atoms of mercaptoacetic acid and mercaptoacetic acid; Examples thereof include hydroxyalkyl mercaptans having 1 to 12 carbon atoms; terpenes such as pinene and terpinolene;

  The polymerization temperature is generally in the range of about 30 ° C to 180 ° C.

  In the production of the specific (meth) acrylic polymer and the specific (meth) acrylic oligomer, a purification step for purifying the polymer obtained by the polymerization reaction may be provided. Thereby, when an unreacted monomer is contained in a polymer obtained by a solution polymerization method or the like, the monomer can be removed. The purification step can be appropriately selected from commonly used purification methods. For example, it can be purified by reprecipitation with methanol or the like.

[Polyether-modified silicone]
The pressure-sensitive adhesive composition of the present invention contains at least one specific polysiloxane that is a polyether-modified silicone having a reactive group. When the pressure-sensitive adhesive composition contains a polyether-modified silicone having a reactive group, excellent antistatic properties can be exhibited, and contamination of the adherend can be effectively suppressed.

  When the specific polysiloxane has a reactive group, low contamination to the adherend is effectively exhibited. This is because the specific polysiloxane reacts with the crosslinking agent by the reactive group, and the compatibility between the (meth) acrylic polymer and the specific polysiloxane is improved by the reactive group, thereby causing contamination due to the specific polysiloxane. This is considered to be suppressed.

  Antistatic property is effectively exhibited because specific polysiloxane has a polyalkyleneoxy group. This is because, for example, the specific polysiloxane is unevenly distributed near the surface of the pressure-sensitive adhesive layer derived from the pressure-sensitive adhesive composition, so that a polyalkyleneoxy group interacting with the ionic compound is present near the surface of the pressure-sensitive adhesive layer. As a result, it is considered to reduce the surface resistance value on the surface of the pressure-sensitive adhesive layer.

  Examples of reactive groups in specific polysiloxanes include reactive groups such as hydroxy groups, carboxy groups, substituted or unsubstituted amide groups, substituted or unsubstituted amino groups, epoxy groups, mercapto groups, and silicon-containing groups. it can. Among them, the specific (meth) acrylic oligomer effectively promotes the reaction between the specific polysiloxane and the crosslinking agent, and from the viewpoint of effectively suppressing the occurrence of contamination on the adherend, a hydroxy group as a reactive group. A polyether-modified silicone having

The specific polysiloxane is preferably a polysiloxane compound containing a structural unit derived from a dialkylsiloxane and a structural unit derived from an alkyl (hydroxypolyalkyleneoxyalkyl) siloxane from the viewpoint of antistatic properties and low contamination to an adherend. .
The alkyl group in the dialkylsiloxane preferably has 1 to 4 carbon atoms, and more preferably 1 carbon atom.
The alkyleneoxy group in the alkyl (hydroxypolyalkyleneoxyalkyl) siloxane preferably has 2 to 4 carbon atoms, and more preferably 2 to 3 carbon atoms. 1-100 are preferable and, as for the content number of the alkyleneoxy group in alkyl (hydroxy polyalkylene oxyalkyl) siloxane, 10-100 are more preferable. The alkyl group in the alkyl (hydroxypolyalkyleneoxyalkyl) siloxane preferably has 1 to 4 carbon atoms.

  When the specific polysiloxane includes a structural unit derived from dialkylsiloxane and a structural unit derived from alkyl (hydroxypolyalkyleneoxyalkyl) siloxane, the number of structural units derived from dialkylsiloxane is preferably 100 or less, 80 is more preferable. Moreover, 2-100 are preferable and, as for the content number of the structural unit derived from alkyl (hydroxy polyalkylene oxyalkyl) siloxane, 2-80 are more preferable.

  The specific polysiloxane is preferably a polysiloxane compound having a hydroxy group represented by the following general formula (1) from the viewpoints of adhesiveness, antistatic properties and low contamination to the adherend.

  In general formula (1), p is the number of repeating dimethylsiloxane structural units and represents a number of 0 to 100. q is the number of repeating methylpropylenesiloxane structural units having a polyoxyethylene group and represents a number of 2 to 100. A is the number of repeating ethyleneoxy structural units and represents a number of 1 to 100, respectively. Here, when the compound represented by the general formula (1) is an aggregate of a plurality of compounds, p, q, and a are average values as the aggregate of the compounds and are rational numbers.

  The repeating number a of the polyethyleneoxy structural unit is a number of 1 to 100, but is preferably a number of 10 to 100. When a is 1 or more, sufficient conductivity is obtained, and the antistatic property tends to be improved. Moreover, when a is 100 or less, the compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be further improved.

Moreover, the repeating number p of a dimethylsiloxane structural unit is a number of 0-100, but it is preferable that it is a number of 1-80. When p is 0 or more, the antistatic property tends to be improved. Further, when p is 100 or less, compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.
Furthermore, the repeating number q of the methylpropylenesiloxane structural unit is 2 to 100, but preferably 2 to 80. When q is 2 or more, sufficient conductivity is obtained, and the antistatic property tends to be improved. Moreover, when q is 100 or less, the compatibility with other components constituting the pressure-sensitive adhesive composition is improved, and the transparency of the pressure-sensitive adhesive layer tends to be improved.

  There is no restriction | limiting in particular about the weight average molecular weight of specific polysiloxane, For example, it can be 5,000 or more and 20,000 or less, and 6,000 or more and 15,000 or less are preferable.

The HLB value of the specific polysiloxane is not particularly limited, but is preferably 5 or more and less than 16, more preferably 7 or more and 15 or less, and more preferably 7 or more and 13 or less from the viewpoint of compatibility with the resin, surface unevenness, and adhesiveness. Is more preferable.
The HLB value is a measure showing the balance between hydrophilicity and hydrophobicity of a specific polysiloxane. In the present invention, the definition of the Griffin method calculated by the following formula 1 is followed. However, when the specific polysiloxane is a commercial product, the catalog data is preferentially adopted.
Formula 1 {(sum of formula weight of hydrophilic group portion) / (molecular weight of specific polysiloxane)} × 20

  The specific polysiloxane has, for example, a dimethylsiloxane structural unit and a methylpropylenesiloxane structural unit having a polyoxyethylene group in the molecule. These structural units may constitute a block polymer or a random polymer.

  Specific examples of the specific polysiloxane represented by the general formula (1) include, for example, “SF-8428”, “FZ-2162”, “SH-3773M”, [manufactured by Toray Dow Corning Co., Ltd. And the like.

  The specific polysiloxane may be selected from the above-mentioned commercially available products, or an organic compound having an unsaturated bond and a polyoxyethylene group may be hydrosilylated with respect to the dimethylpolysiloxane main chain having silicon hydride. It can also be obtained by grafting by a chemical reaction.

  The content of the specific polysiloxane in the pressure-sensitive adhesive composition of the present invention is preferably 0.05 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer. More preferably, it is 1 part by mass or more and 1.0 part by mass or less, and further preferably 0.1 part by mass or more and 0.3 part by mass or less.

  When the content of the specific polysiloxane is equal to or higher than the lower limit, the antistatic property when the surface protective film is peeled can be more effectively obtained. In addition, since the content of the specific polysiloxane is not more than the above upper limit value, the occurrence of contamination on the adherend is suppressed, and the compatibility with the specific (meth) acrylic polymer is lowered, resulting in white turbidity. This can be suppressed.

  The total content of the specific (meth) acrylic oligomer and the specific polysiloxane in the pressure-sensitive adhesive composition is 0.1 parts by mass or more and 7.0 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic polymer. It is preferable that it is 0.2 mass part or more and 4.0 mass part or less, and it is still more preferable that it is 0.3 mass part or more and 3.0 mass part or less.

  The mass ratio of the specific polysiloxane to the specific (meth) acrylic oligomer in the pressure-sensitive adhesive composition (specific polysiloxane / specific (meth) acrylic oligomer) is the viewpoint of antistatic properties and low contamination to the adherend. Therefore, it is preferably 0.01 or more and 4.0 or less, more preferably 0.03 or more and 2.0 or less, and further preferably 0.07 or more and 0.75 or less.

The pressure-sensitive adhesive composition of the present invention may contain, in addition to the specific polysiloxane, a polyether-modified silicone having no reactive group as long as the effects of the present invention are not impaired.
Examples of the polyether-modified silicone having no reactive group include compounds in which the terminal of the polyalkyleneoxy group is an alkoxy group, an acyloxy group, or the like.

  When the pressure-sensitive adhesive composition of the present invention contains a polyether-modified silicone having no reactive group, the content is preferably 0.05% by mass or less based on the total mass of the polysiloxane compound. More preferably, it is 0.03 mass% or less.

[Ionic compounds]
The pressure-sensitive adhesive composition of the present invention contains at least one ionic compound. When the pressure-sensitive adhesive composition contains an ionic compound, excellent antistatic properties can be exhibited. Examples of the ionic compound include alkali metal salts and organic salts. Alkali metal salts are useful in that they can exhibit excellent antistatic properties while suppressing the occurrence of contamination on the adherend because they have high ion dissociation properties even in a very small amount. In addition, since the organic salt exhibits excellent conductivity when dissociated into ions, it is useful in that it can provide necessary antistatic properties only by being contained in a small amount in the pressure-sensitive adhesive layer.

The alkali metal salt is not particularly limited as long as it is a metal salt having a cation such as lithium ion (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ), rubidium ion (Rb ⁺ ) or the like.
For example, at least one cation selected from the group consisting of Li ⁺ , Na ⁺ , K ⁺ and Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , (FSO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ A metal salt composed of a seed anion is preferably used.

Among them, alkali metal salts are LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (FSO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₂ from the viewpoint of antistatic properties. Preferred are lithium salts such as N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li ( C ₂ F ₅ SO ₂ ) ₂ N and Li (CF ₃ SO ₂ ) ₃ C are more preferable. These alkali metal salts may be used individually by 1 type, and 2 or more types may be mixed and used for them.

The organic salt contains an organic cation and its counter ion.
The organic salt preferably has a melting point of 30 ° C. or higher. It is preferable for the melting point of the organic salt to be 30 ° C. or higher because there is little migration to the adherend and excellent low contamination to the adherend.
Examples of the organic cation include an imidazolium cation, a pyridinium cation, an alkylpyrrolidinium cation, an ammonium cation having an organic group as a substituent, a sulfonium cation having an organic group as a substituent, and a phosphonium cation having an organic group as a substituent. Is mentioned. Among these, when contained in the pressure-sensitive adhesive layer of the optical member surface protective film, a pyridinium cation and an imidazolium cation are preferable from the viewpoint of further reducing charge when peeling the release film provided on the pressure-sensitive adhesive layer. .

The anion part which becomes a counter ion of the organic cation is not particularly limited, and may be either an inorganic anion or an organic anion. Among them, in particular, is excellent in antistatic property, a fluorine-containing anion preferably containing a fluorine atom, more hexafluorophosphate anions (PF 6 ^_-) is preferred.

  Preferable examples of the organic salt include pyridinium salt, imidazolium salt, alkylammonium salt, alkylpyrrolidinium salt, alkylphosphonium salt and the like. Of these, a pyridinium salt and an imidazolium salt are preferable, and a salt of a pyridinium cation, an imidazolium cation and a fluorine-containing anion is particularly preferable.

  The content of the antistatic agent in the pressure-sensitive adhesive composition of the present invention is preferably 0.05 parts by mass or more and 0.50 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic polymer. More preferably, it is at least 0.30 parts by mass. When the content of the antistatic agent is 0.05 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic polymer, sufficient charging characteristics can be obtained. On the other hand, when the content of the antistatic agent is 0.50 parts by mass or less, an antistatic effect rate with respect to the content can be sufficiently obtained.

  In the pressure-sensitive adhesive composition of the present invention, the mass ratio of the total content of the specific (meth) acrylic oligomer and the specific polysiloxane to the content of the ionic compound ((specific (meth) acrylic oligomer + specific polysiloxane) / ion From the viewpoint of antistatic properties and adhesiveness, the functional compound is preferably from 1 to 20, and more preferably from 2 to 15.

  The total content of the specific (meth) acrylic oligomer, the specific polysiloxane, and the alkali metal salt in the pressure-sensitive adhesive composition of the present invention is 0.15 parts by mass or more with respect to 100 parts by mass of the specific (meth) acrylic polymer. It is preferably 7.5 parts by mass or less, more preferably 0.3 parts by mass or more and 5.0 parts by mass or less, and further preferably 0.5 parts by mass or more and 2.5 parts by mass or less.

[Crosslinking agent]
The pressure-sensitive adhesive composition of the present invention contains a crosslinking agent. The crosslinking agent is not particularly limited, and examples thereof include a polyisocyanate compound, a polyepoxy compound, a polyaziridine compound, a melamine formaldehyde condensate, a metal salt, and a metal chelate compound. These crosslinking agents can be used singly or in combination of two or more.

  Of these crosslinking agents, polyisocyanate compounds are preferred. By using a polyisocyanate compound, a crosslinking reaction between the polyisocyanate compound and the specific (meth) acrylic polymer, the specific (meth) acrylic oligomer, the specific polysiloxane, and the specific polysiloxane by the (meth) acrylic oligomer Since the reaction with the polyisocyanate compound is effectively promoted, the antistatic property and the low contamination property to the adherend can be further improved.

  Examples of the polyisocyanate compound include aromatic polyisocyanate compounds such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate; for example, hydrogenated products of hexamethylene diisocyanate, isophorone diisocyanate, and aromatic polyisocyanate compounds. Examples thereof include aliphatic or alicyclic polyisocyanate compounds such as: dimers or trimers of these polyisocyanate compounds; adducts of these polyisocyanate compounds and polyol compounds such as trimethylolpropane.

  Among these, from the viewpoint of curability of the pressure-sensitive adhesive composition and pot life of the coating liquid, among these polyisocyanate compounds, a group consisting of hexamethylene diisocyanate and hexamethylene diisocyanate dimers, trimers and adducts. At least one selected from the above is preferable, and a trimer of hexamethylene diisocyanate is particularly preferable. These polyisocyanate compounds can be used individually by 1 type or in mixture of 2 or more types.

  Polyisocyanate compounds include, for example, “Coronate HX”, “Coronate HL-S”, “Coronate 2234”, “Aquanate 200”, “Aquanate 210” (manufactured by Tosoh Corporation), “Sumidule N3300”, “Desmodur N3400” (manufactured by Sumitomo Bayer Urethane Co., Ltd.), “Duranate E-405-80T”, “Duranate 24A-100”, “Duranate TSE-100” (manufactured by Asahi Kasei Chemicals), "Takenate D-110N", "Takenate D-120N", "Takenate M-631N", "MT-Olestar NP1200" (above, manufactured by Mitsui Takeda Chemical Co., Ltd.), etc. are suitable. Can be used for

  The content of the crosslinking agent is preferably 0.1 parts by mass or more and 10 parts by mass or less, and 0.5 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the specific (meth) acrylic polymer. Is more preferable.

  The pressure-sensitive adhesive composition of the present invention may contain an organic tin compound such as dibutyltin laurate as a crosslinking catalyst, if necessary. However, the pressure-sensitive adhesive composition of the present invention is excellent in curability without using a crosslinking catalyst, having a short curing time, and having an initial value by setting the acid value of the specific (meth) acrylic polymer to 2 mgKOH / g or more. A pressure-sensitive adhesive composition having a high curing rate can be obtained.

  In particular, the pressure-sensitive adhesive composition of the present invention includes a specific (meth) acrylic polymer having an acid value of 2 mgKOH / g or more, a specific (meth) acrylic oligomer, and a specific polysiloxane. Thus, it is possible to achieve all of the curability in the absence of a crosslinking catalyst, the antistatic property, and the low contamination to the adherend, which are difficult to achieve.

  In addition to the specific (meth) acrylic polymer, specific (meth) acrylic oligomer, specific polysiloxane, ionic compound, crosslinking agent and crosslinking catalyst described above, the pressure-sensitive adhesive composition of the present invention, if necessary, Weathering stabilizers, tackifiers, plasticizers, softeners, peeling aids, dyes, pigments, inorganic fillers, surfactants and the like can be appropriately contained.

<Optical member surface protective film>
The optical member surface protective film of the present invention is configured by providing a base material and a pressure-sensitive adhesive layer provided on the base material and formed using the pressure-sensitive adhesive composition of the present invention.
In the optical member surface protective film of the present invention, the pressure-sensitive adhesive layer is configured as a layer derived from the above-described pressure-sensitive adhesive composition, thereby suppressing generation of static electricity due to peeling charging and low contamination to an adherend. Excellent for everything.

The base material used for the optical member surface protective film of the present invention can be selected from any material as long as an adhesive layer can be formed on the base material.
Base materials are polyester resin, acetate resin, polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin from the viewpoint of inspection and management of optical members through fluoroscopy. The film which consists of etc. can be mentioned. Of these, polyester resins are preferable from the viewpoint of surface protection performance, and polyethylene terephthalate resins are particularly preferable from the viewpoint of practicality.

  Generally the thickness of a base material can be 500 micrometers or less, Preferably it is 5 micrometers-300 micrometers, More preferably, the thickness of about 10 micrometers-200 micrometers can be illustrated.

  An antistatic layer may be provided on one side or both sides of the base material for the purpose of preventing charging at the time of peeling. The surface of the substrate on the side where the pressure-sensitive adhesive layer is provided may be subjected to a corona discharge treatment or the like in order to improve the adhesion with the pressure-sensitive adhesive layer.

As a method for forming a pressure-sensitive adhesive layer formed on a substrate, for example, a pressure-sensitive adhesive composition containing a polyisocyanate compound is diluted as it is or with an appropriate solvent as necessary, and this is used as a surface protective base film ( It is possible to employ a method in which the solvent is removed after drying directly on the base material.
Further, first, for example, a pressure-sensitive adhesive composition containing a polyisocyanate compound is applied on a release sheet made of an appropriate film such as paper or polyester film which has been subjected to a release treatment with a silicone resin, and then dried by heating and adhered. It is also possible to adopt a method in which an adhesive layer is formed, and then the pressure-sensitive adhesive layer side of the release sheet is pressed against a surface protective base film (base material) to transfer the pressure-sensitive adhesive layer to the protective film.

In the optical member surface protective film of the present invention, the pressure-sensitive adhesive layer contains a polyisocyanate compound as a cross-linking agent of the pressure-sensitive adhesive composition, and by this polyisocyanate compound, a specific (meth) acrylic polymer, a specific (meth) acrylic compound The pressure-sensitive adhesive layer is preferably a cross-linked oligomer and specific polysiloxane. Thereby, the antistatic property of an adhesive layer and the low contamination property with respect to a to-be-adhered body improve more.
Conditions for crosslinking the specific (meth) acrylic polymer, specific (meth) acrylic oligomer and specific polysiloxane with a crosslinking agent are not particularly limited.

  The pressure-sensitive adhesive layer has a sufficient adhesive force for a large optical member used for, for example, a liquid crystal display screen of 20 inches or more (adhesive force at a low speed peeling is sufficiently large) and easily at a high speed peeling. It is preferable that it can peel (the adhesive force at the time of high speed peeling does not become large).

  That is, the adhesive strength of 180 ° peel at 23 ° C. to the optical member is preferably 0.05 N / 25 mm or more at a peeling speed of 0.3 m / min (low speed peeling). More preferably, it is 06 N / 25 mm or more. When the adhesive force at the time of low-speed peeling is 0.05 N / 25 mm or more, the occurrence of turning or deviation is suppressed.

  Moreover, since the workability at the time of high-speed peeling in a large area decreases as the adhesive strength increases, the adhesive strength (peeling force) at a peeling speed of 30 m / min (high-speed peeling) is preferably less than 1.5 N / 25 mm. More preferably, it is less than 1.2 N / 25 mm, and still more preferably less than 0.9 N / 25 mm.

  Furthermore, since the optical member may be damaged if the charge at the time of peeling is large, the pressure-sensitive adhesive composition of the present invention is 30 m / min at the time of peeling to a polarizing plate (trade name: SRDB31E, manufactured by Sumitomo Chemical Co., Ltd.). The absolute value of the peeling band voltage is preferably 0.9 kV or less, more preferably 0.7 kV or less, and further preferably 0.5 kV or less.

Further, from the viewpoint of preventing charging on the film side at the time of peeling, the surface resistance value of the pressure-sensitive adhesive layer is preferably less than 5.0E + 11 (Ω / □) (5.0 × 10 ¹¹ Ω / □).

  The thickness of the pressure-sensitive adhesive layer formed on the substrate can be appropriately set according to the adhesive force required for the optical member surface protective film, the optical member surface roughness, etc., and is generally 1 μm to 100 μm, preferably 5 μm. A thickness of about 50 μm, more preferably about 15 μm to 30 μm can be exemplified.

The optical member surface protective film thus obtained is laminated on the surface of the optical member to protect the surface of the optical member from being contaminated or damaged, and when the optical member is processed into a liquid crystal display device or the like. Is used for each process such as punching, inspection, transportation, and assembly of the liquid crystal display device in a state where the protective film is laminated on the optical member. If necessary, autoclave treatment, high temperature aging treatment, etc. It is peeled and removed from the optical member when it is subjected to heat and pressure treatment and surface protection is no longer necessary.
The optical member on which the optical member surface protective film is laminated includes a polarizing plate, a reflecting plate, a transflective plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), a viewing angle compensation film, and a brightness enhancement film. , Prism sheets, lens sheets, diffuser plates and the like used for display devices.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

(Production Example A)
-Production of (meth) acrylic polymer A-
In a reaction vessel equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 20 parts of ethyl acetate and 10 parts of toluene are placed, and in another container, 60.0 parts of butyl acrylate and 2-ethylhexyl acrylate 34. 3 parts, 5 parts of 4-hydroxybutyl acrylate as a monomer having a hydroxy group and 0.7 parts of acrylic acid as a monomer having a carboxy group are mixed to form a monomer mixture, 25% by weight of which is contained in a reaction vessel Then, after the air in the reaction vessel was replaced with nitrogen gas, 0.02 part of azobisbutyronitrile (hereinafter referred to as AIBN) was added as a polymerization initiator, and the reaction vessel was stirred in a nitrogen atmosphere. The temperature of the mixture was raised to 70 ° C. to initiate the initial reaction. After the initial reaction was almost completed, the remaining monomer mixture 75% by mass and a mixture of 20 parts of ethyl acetate, 10 parts of toluene and 0.2 part of AIBN were allowed to react for about 2 hours, followed by further reaction for 2 hours. I let you. Thereafter, a solution in which 0.25 part of AIBN was dissolved in 25 parts of toluene was added dropwise over 1 hour, and the mixture was further reacted for 1.5 hours. After completion of the reaction, the reaction mixture was diluted with 100 parts of toluene to obtain a (meth) acrylic polymer A solution.
The acid value of (meth) acrylic polymer A (shown as “Polymer A” in the table) was 5.4, the weight average molecular weight was 440,000, and the degree of dispersion was 7.6.

(Production Examples B to F)
-Production of (meth) acrylic polymers BF-
(Meth) acrylic polymer B to F solutions were produced in the same manner as in Production Example A, except that the monomer composition was changed to the monomer composition shown in Table 1 and the initiator amount and the like were appropriately adjusted. Table 1 shows the acid value, weight average molecular weight, and degree of dispersion of the obtained (meth) acrylic polymers B to F (in the table, indicated as “polymer B” to “polymer F”, respectively).

(Production example a)
-Production of (meth) acrylic oligomer a-
In a reaction vessel equipped with a thermometer, a stirring blade, a nitrogen gas inlet tube, a cooler, and a dropping funnel, 100.0 parts of methyl ethyl ketone was placed and heated to the reflux temperature while stirring under a nitrogen atmosphere. In the dropping funnel, 10 parts of methoxypolyethylene glycol methacrylate (alkylene oxide group content: 23), 89.7 parts of n-butyl methacrylate, 0.3 part of acrylic acid, 100.0 parts of methyl ethyl ketone, And a mixed solution of 5.0 parts of azobisisobutyronitrile were sequentially added to the reaction vessel at the reflux temperature over 120 minutes. Then, it was made to react, maintaining a reflux temperature for 240 minutes, and reaction was complete | finished. In this way, a (meth) acrylic oligomer a solution was obtained.
The acid value of (meth) acrylic oligomer a (denoted as “oligomer a” in the table) was 2.3, and the weight average molecular weight was 7,000.

(Production Examples b to d)
-Production of (meth) acrylic oligomers b to d-
A (meth) acrylic oligomer cd solution was produced in the same manner as in Production Example a except that the monomer composition was changed to the monomer composition shown in Table 2 and the initiator amount and the like were appropriately adjusted. Table 2 shows the acid values and weight average molecular weights of the obtained (meth) acrylic oligomers b to d (labeled “oligomer b” to “oligomer d” in the table, respectively).

In addition, the detail of the symbol of each component in Table 1, 2 is as follows.
· BA: n-butyl acrylate · 2EHA: 2-ethylhexyl acrylate · 4HBA: 4-hydroxybutyl acrylate · AA: acrylic acid · n-BMA: n-butyl methacrylate · MePEGMA: methoxypolyethylene glycol methacrylate (number of alkylene oxide groups) (Average number of moles added): 23)
Mw: weight average molecular weight Mw / Mn: dispersity

<Example 1>
In a four-necked flask equipped with a stirring blade, a thermometer, a condenser, and a dropping funnel, 100 parts of the (meth) acrylic polymer A solution obtained in Production Example A was obtained in Production Example a in terms of solid content. 0.82 parts of (meth) acrylic oligomer a solution in terms of solid content, as a specific polysiloxane SH3773M (manufactured by Toray Dow Corning Co., Ltd., polyether-modified silicone represented by general formula (1), polyether terminal : 0.15 part of hydroxy group, HLB value = 8) and 0.15 part of lithium trifluoromethanesulfonic acid as an ionic compound, respectively, and mixed and stirred for 4.0 hours while keeping the liquid temperature in the flask at 25 ° C. To obtain a mixed solution.
To this, 3.0 parts of N3300 (polyisocyanate compound, trade name: Sumidur N3300, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene diisocyanate trimer, solid content: 100% by mass) is added as a crosslinking agent. The mixture was sufficiently stirred to obtain a pressure-sensitive adhesive composition.
Using the obtained pressure-sensitive adhesive composition, a test surface protective film was prepared according to the following method for preparing a test surface protective film, and various physical property tests were performed. The obtained results are shown in Table 3.

(1) Preparation of surface protective film for test Polyethylene terephthalate (PET) film (trade name: Tetron G2, film thickness: 38 μm, manufactured by Teijin Tetron Film Co., Ltd.) and the coating amount after drying is 20 g / m 2 After applying the pressure-sensitive adhesive composition and drying it with a hot air circulation dryer at 100 ° C. for 60 seconds to form a pressure-sensitive adhesive layer, a release film (PET surface-treated with a silicone-based release agent) Film, product name: film binder 100E-0010NO23, manufactured by Fujimori Kogyo Co., Ltd.] with the pressure-sensitive adhesive layer surface coming into contact with each other, pressure-bonded through a pressure nip roll, and bonded together, and then the environment at 23 ° C. and 50% RH. The surface protection film for a test was obtained by curing for 5 days.

(2) Evaluation of contamination (bubble traces)
A polarizing plate (trade name: SRDB31E, manufactured by Sumitomo Chemical Co., Ltd.) is attached to the front and back of a glass substrate (Matsunami Glass Industry Co., Ltd., blue plate glass) with an acrylic adhesive so that the polarization axis is in a crossed Nicol state. In addition, a substrate with a polarizing plate was obtained. The acrylic pressure-sensitive adhesive to be used may be any pressure-sensitive adhesive as long as it does not peel off during the test and a certain degree of transparency is obtained.
The release film was peeled off from the test surface protective film prepared in (1) above, and the pressure-sensitive adhesive layer surface was bonded to the polarizing plate of the substrate with a polarizing plate. After 5 to 10 seconds, the test surface protective film was peeled off from the adherend, and bonded again so that air bubbles entered immediately after. Thereafter, it was left in a dryer at 60 ° C. for 3 hours. Furthermore, after leaving for 30 minutes in an environment of 25 ° C. and 50% RH, the test surface protective film was peeled off, and bubble marks on the polarizing plate surface were visually confirmed under a xenon lamp (Polarion, NP1 type). Contamination was evaluated according to the following evaluation criteria. In addition, the thinner the bubble trace on the polarizing plate surface, the smaller the residue derived from the surface protective film for testing on the polarizing plate surface, and the lower the contamination of the adherend.

~Evaluation criteria~
A: A level where no bubble marks can be confirmed or the bubble marks can be confirmed very thin, but no problem in practical use.
B: Although the bubble trace can be confirmed to be thin, it is a level at which there is no practical problem.
C: A level at which bubble marks can be clearly confirmed and cannot be put to practical use.

(3) Evaluation of antistatic property -Surface resistance value-
The release film was peeled off from the test surface protective film prepared in (1) above, and the surface resistance value (Ω / □) of the surface of the exposed pressure-sensitive adhesive layer was measured using a surface resistance measuring device (R12704 REISTIVITY, manufactured by Advantest Corporation). (CHAMBER).

-Stripping voltage-
After cutting the test surface protective film prepared in (1) above to 25 mm × 150 mm, the test piece of the test pressure-sensitive adhesive sheet was polarized using the desktop laminator while peeling off the release film. A test sample was prepared by pressure bonding to a plate (trade name: SRDB31E, manufactured by Sumitomo Chemical Co., Ltd.). This test sample was allowed to stand for 24 hours under the conditions of 23 ° C. and 50% RH (conditioning treatment), and then peeled off under the conditions of peeling angle: 180 ° and peeling speed: 30 m / min (high-speed peeling conditions). The potential (kV) of the polarizing plate surface generated at this time was measured with a potential measuring device (KSD-0303, manufactured by Kasuga Electric Co., Ltd.) fixed at a predetermined position. The measurement was performed in an environment of 23 ° C. and 50% RH.

Based on the measured values of the surface resistance value and the peeling voltage, the antistatic property was evaluated according to the following evaluation criteria. In addition, if it was more than evaluation B, it was judged that it was excellent in antistatic property.
~Evaluation criteria~
A: The surface resistance value is less than 1.0E + 11 (Ω / □), and the absolute value of the peeling band voltage is less than 0.7 kV.
B: The surface resistance value is 1.0E + 11 (Ω / □) or more and less than 5.0E + 11 (Ω / □), and the absolute value of the peeling band voltage is less than 0.9 kV.
C: The surface resistance value is 5.0E + 11 (Ω / □) or more, or the absolute value of the peeling band voltage is 0.9 kV or more.

(4) Evaluation of peelability The peelability was evaluated by measuring the adhesive strength at the time of high-speed peeling (peeling speed: 30 m / min).
After cutting the test surface protective film prepared in the above (1) to 25 mm × 150 mm, the release film is peeled off from the film piece, and a polarizing plate (trade name; SRDB31E, Sumitomo Chemical Co., Ltd.) is used by using a table laminator. )) To obtain a test sample.
This test sample was allowed to stand (conditioning treatment) for 24 hours in an environment of 23 ° C. and 50% RH. Thereafter, the adhesive force when the test surface protective film was peeled from the polarizing plate in the long side (150 mm) direction along with the adhesive layer at a peeling angle of 180 ° and a peeling speed of 30 m / min was measured.

(5) Curability evaluation-Curing time-
The time required for curing (curing time) of the pressure-sensitive adhesive composition obtained above was evaluated by measuring the gel fraction as follows.
The pressure-sensitive adhesive composition was applied on a release film surface-treated with a silicone-based release agent, and a pressure-sensitive adhesive layer was formed so that the thickness after drying was 25 μm to obtain a pressure-sensitive adhesive film. Next, after the formed adhesive film was stored in an environment of 23 ° C. and 50% RH for a predetermined time, the gel fraction was measured every 24 hours until 192 hours passed, respectively. Comparison of gel fraction after elapse of predetermined storage time and gel fraction after elapse of 192 hours (8 days), storage required for difference in gel fraction between the two to be 3% or less Time was taken as the curing time. Tables 3 to 5 show the curing time in days.

The gel fraction was measured as follows.
1. About 0.25 g of the pressure-sensitive adhesive layer was affixed to a precisely weighed 250-mesh wire mesh (100 mm × 100 mm), and a sample was prepared by wrapping so that the gel content did not leak. Thereafter, the mass was accurately measured with a precision balance.
2. The obtained sample was immersed in 80 ml of ethyl acetate for 3 days.
3. A sample was taken out, washed with a small amount of ethyl acetate, and dried at 120 ° C. for 24 hours. After standing to cool, the mass was accurately measured with a precision balance.
4). The gel fraction was calculated by the following formula.
Gel fraction (mass%) = (Z−X) / (Y−X) × 100
Where X is the mass (g) of the wire mesh, Y is the mass (g) of the sample before immersion (wire mesh with the adhesive layer attached), and Z is the mass (g) of the sample after being immersed in ethyl acetate and dried. It is.

-Initial curing rate-
The initial curing rate of the pressure-sensitive adhesive composition obtained above was evaluated by measuring the stress value as follows.
On a release film (PET film surface-treated with a silicone release agent, trade name: film binder 100E-0010NO23, manufactured by Fujimori Kogyo Co., Ltd.), the coating amount after drying is 20 g / m ^2. Thus, the adhesive composition was applied, the “stress / strain curve” of the adhesive composition 5 minutes after application was measured, and the stress value at 100% strain was measured.

The initial curability was evaluated based on the measured stress value according to the following evaluation criteria.
~Evaluation criteria~
A: It was 0.01 N / mm ² or more.
B: It was 0.005 N / mm ² or more and less than 0.01 N / mm ² .
C: It was less than 0.005 N / mm ² .

<Examples 2 to 13 and Comparative Examples 1 to 3>
In Example 1, a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that each component used for preparing the pressure-sensitive adhesive composition was changed as shown in Tables 3 to 5, respectively. Various physical property tests were conducted. The obtained results are shown in Tables 3 to 5.

<Example 14>
In Example 1, (meth) acrylic polymer A was changed to (meth) acrylic polymer E, and dioctyltin laurate (trade name: ADK STAB OT-1, manufactured by ADEKA) was used as a crosslinking catalyst 300 times with acetylacetone. A pressure-sensitive adhesive composition of Example 14 was prepared in the same manner as in Example 1 except that 0.02 part of the cross-linked catalyst solution diluted in a solid content was blended to prepare a mixed solution. Various physical property tests were conducted. The results obtained are shown in Table 4.

The details of the abbreviations of each component in Tables 3 to 5 are as follows, and the content is a value in terms of solid content.
SH3773M: polyether-modified silicone having a reactive group represented by the general formula (1) (trade name: SH3773M, manufactured by Toray Dow Corning Co., Ltd., polyalkyleneoxy group end: hydroxy group (reactive group) , HLB value = 8, specific polysiloxane)
FZ2162: polyether-modified silicone having a reactive group represented by the general formula (1) (trade name: FZ-2162, manufactured by Toray Dow Corning Co., Ltd., end of polyalkyleneoxy group: hydroxy group (reactive Group), HLB value = 14, specific polysiloxane)
SH8400: polyether-modified silicone having no reactive group (trade name: SH8400, manufactured by Toray Dow Corning Co., Ltd., end of polyalkyleneoxy group: acetyloxy group, HLB value = 7)
LiTFS: lithium trifluoromethanesulfonic acid (alkali metal salt)
LiTFSI: Lithium bis (trifluoromethanesulfonylimide) (alkali metal salt)
HPPHFP: N-hexylpyridinium hexafluorophosphate (organic salt, melting point 45 ° C.)
N3300: isocyanate compound having an isocyanurate structure which is a trimer of hexamethylene diisocyanate (trade name: Sumidur N3300, manufactured by Sumika Bayer Urethane Co., Ltd., crosslinking agent (polyisocyanate compound))
C-L: Trimethylolpropane adduct of tolylene diisocyanate (trade name: Coronate L, solid content: 75% by mass, manufactured by Tosoh Corporation, cross-linking agent (polyisocyanate compound))

In the comparative example 1, since the (meth) acrylic-type polymer whose acid value is 16 is used, it turns out that it is inferior to antistatic property. In the comparative example 2, since the (meth) acrylic-type oligomer whose acid value is 0 is used, it turns out that it is inferior to the low pollution property with respect to a to-be-adhered body. In Comparative Example 3, it can be seen that since the polyether-modified silicone having no reactive group is used, the low contamination property to the adherend is poor.
On the other hand, it can be seen that the test surface protective film formed from the pressure-sensitive adhesive composition of the present invention is excellent in low contamination and antistatic properties to the adherend.

Claims (6)

A (meth) acrylic polymer having a hydroxy group and having an acid value of 0 mgKOH / g or more and less than 16 mgKOH / g;
An alkylene oxide chain-containing (meth) acrylic oligomer having an acid value of 0.1 mgKOH / g to 40 mgKOH / g;
A polyether-modified silicone having a reactive group;
A crosslinking agent;
An ionic compound;
A pressure-sensitive adhesive composition comprising:   The said alkylene oxide chain containing (meth) acrylic oligomer and the said polyether modified silicone are 0.1-7.0 mass parts in total with respect to 100 mass parts of said (meth) acrylic-type polymers. Adhesive composition.   The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the acid value of the (meth) acrylic polymer is 2 mgKOH / g or more and 12 mgKOH / g or less.   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the reactive group of the polyether-modified silicone is a hydroxy group, and the crosslinking agent is a polyisocyanate compound.   The pressure-sensitive adhesive composition according to any one of claims 1 to 4, which is used for an optical member surface protective film. A substrate;
A pressure-sensitive adhesive layer provided on the base material and derived from the pressure-sensitive adhesive composition according to any one of claims 1 to 4,
An optical member surface protective film comprising: