JP7177581B2 - Adhesive composition, adhesive sheet, and optical member - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive composition, an adhesive sheet, and an optical member. In particular, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition is used to be attached to plastic products, etc., where static electricity is likely to occur (e.g., liquid crystal display panels, plasma display panels (PDP), organic electroluminescence (EL) displays, etc.). Among them, it is particularly suitable for protecting the surface of optical members (e.g., polarizing plates, wave plates, retardation plates, optical compensation films, reflective sheets, and brightness enhancement films used in liquid crystal displays). It is useful as a surface protection film to be used.

A surface protection film (also referred to as a surface protection sheet) generally has a structure in which an adhesive layer is provided on a film-like base film (support). Such a protective film is attached to an adherend (object to be protected) via the pressure-sensitive adhesive layer, and is used for the purpose of protecting the adherend from scratches and stains during processing, transportation, and the like. For example, a liquid crystal display panel is formed by bonding an optical member such as a polarizing plate or a wavelength plate to a liquid crystal cell via an adhesive layer. In the manufacture of such a liquid crystal display panel, the polarizing plate to be bonded to the liquid crystal cell is once manufactured in a roll form, unwound from the roll, and cut into a desired size according to the shape of the liquid crystal cell. . Here, in order to prevent the polarizing plate from being damaged by rubbing against a transport roll or the like in the intermediate process, a surface protective film is adhered to one side or both sides (typically one side) of the polarizing plate. This surface protection film is peeled off and removed when it is no longer needed.

Since surface protective films and optical members are usually made of plastic materials, they have high electrical insulation and generate static electricity due to friction and peeling. For this reason, static electricity is likely to be generated when the surface protective film is peeled off from an optical member such as a polarizing plate. There is also a concern that the panel may be damaged. In addition, the presence of static electricity can be a factor in attracting dust and reducing workability. Under such circumstances, the surface protective film is subjected to antistatic treatment. For example, as the surface layer (top coat layer, back layer) of the surface protective film, an antistatic layer is formed or an antistatic coating is applied. provides an antistatic function (see Patent Documents 1 and 2).

In addition, in order to impart antistatic properties to the adhesive layer itself constituting the surface protective film, the adhesive is made to contain an ionic compound such as an alkali metal salt or an ionic liquid that functions as an antistatic agent. (See Patent Document 3).

In addition, when the surface protective film is attached to the adherend (polarizing plate, etc.), the adherend (polarizing plate, etc.) to which the surface protective film is attached may cause unnecessary curling or unintended curling (curling). refers to the phenomenon of warping, for example, a phenomenon in which a flat plate is warped entirely to one side, or a phenomenon in which a flat plate is warped in a wavy manner, etc.). Adjustability is required. Unnecessary or unintended curling results in poor handleability, and for example, when an adherend such as a polarizing plate is adhered to a liquid crystal cell, problems such as entrapment of air bubbles may occur.

When a flat plate-shaped adherend curls, a shearing force associated with the curl acts on the adhesive layer of the surface protection film attached to the adherend. There is a gradual slippage (displacement) between the layers, so an improvement in the shear force during low-speed peeling is required.

In addition, in order to prevent the surface protective film from lifting or peeling during processing and transportation of the adherend (protected object), it has an appropriate adhesive strength, and at the time of low-speed peeling, it is easy to peel (removable). ) is required.

Therefore, in order to achieve easy release, various techniques have been applied to adhesive compositions used in surface protection films. For example, it has been reported that the polymer used in the pressure-sensitive adhesive composition contains a component having a high glass transition temperature (Tg), a reactive surfactant, or the like, or that the pressure-sensitive adhesive composition is highly crosslinked (e.g., See Patent Document 4).

However, in the above method, even if it is possible to achieve easy release, the addition of additives such as ionic compounds and surfactants may cause the interface between the adhesive layer and the adherend to contain additives such as bleeds out, causing contamination, and along with that, there is concern that slippage (displacement) is likely to occur.

JP-A-2004-223923 JP 2008-255332 A JP-A-9-165460 JP-A-2002-221906

Therefore, in view of the above circumstances, as a result of intensive research, the present invention has found that slippage (displacement), lifting and peeling do not easily occur with respect to optical members such as polarizing plates, excellent curl controllability, and a low peeling electrification voltage. An object of the present invention is to provide a pressure-sensitive adhesive composition from which a pressure-sensitive adhesive layer or pressure-sensitive adhesive sheet can be obtained, a pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition, and an optical member to which the pressure-sensitive adhesive sheet is attached.

That is, the adhesive composition of the present invention is characterized by containing an adhesive polymer, a fluorine-based oligomer having a weight average molecular weight of 3500 or more, and an ionic compound.

The adhesive composition of the present invention preferably contains an oxyalkylene group-containing compound.

In the adhesive composition of the present invention, the adhesive polymer is preferably at least one selected from the group consisting of (meth)acrylic polymers, urethane polymers and silicone polymers.

The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition on at least one side of a base film, and the fluorine-based oligomer is formed inside and/or on the surface of the pressure-sensitive adhesive layer. preferably present.

In the pressure-sensitive adhesive sheet of the present invention, it is preferable that a separator is attached to the surface of the pressure-sensitive adhesive layer opposite to the surface in contact with the base film.

In the pressure-sensitive adhesive sheet of the present invention, the fluorine-based oligomer is preferably present on the surface of the separator that contacts the pressure-sensitive adhesive layer.

It is preferable that the optical member of the present invention is attached with the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive sheet obtained by peeling the separator from the pressure-sensitive adhesive sheet.

By using a pressure-sensitive adhesive composition containing a specific fluorine-based oligomer and an ionic compound, the present invention provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition as an optical member such as a polarizing plate. Since the occurrence of slippage (displacement), lifting, and peeling can be suppressed after lamination, the curl control property is excellent, and the peel electrification voltage can be suppressed low, which is useful.

BRIEF DESCRIPTION OF THE DRAWINGS It is typical sectional drawing which shows one structural example of the adhesive sheet (surface protection film) which concerns on this invention. FIG. 4 is an explanatory diagram showing a method of measuring a peeling electrification voltage;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.

<Overall Structure of Adhesive Sheet (Surface Protection Film)>
The adhesive sheets disclosed herein are generally in the form of adhesive tapes, adhesive labels, adhesive films, etc., and are particularly used as optical components (e.g., polarizing plates, wavelength plates, and other liquid crystal display panel components). It is suitable as a surface protection film for protecting the surface of optical parts during processing and transportation of optical parts. The pressure-sensitive adhesive layer in the surface protection film is typically formed continuously, but is not limited to such a form, and is formed in a regular or random pattern such as dots or stripes. It may be an adhesive layer. In addition, the surface protection film disclosed herein may be roll-shaped or sheet-shaped.

<Base film>
The pressure-sensitive adhesive sheet (surface protective film) of the present invention is characterized by having a base film. In the technique disclosed herein, the resin material that constitutes the base film can be used without any particular limitation. It is preferable to use a material having excellent properties such as flexibility and dimensional stability. In particular, since the base film has flexibility, the pressure-sensitive adhesive composition can be applied with a roll coater or the like, and can be wound into a roll, which is useful.

Examples of the substrate film (substrate, support) include polyester-based polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonates. acrylic polymer such as polymethyl methacrylate; It can be preferably used as the base film. Other examples of the resin material include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymers; olefin-based polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; vinyl chloride-based polymer; amide-based polymer such as nylon 6, nylon 6,6, and aromatic polyamide; and the like are used as resin materials. Still other examples of the resin material include imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, and vinyl butyral-based polymers. , arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and the like. A base film made of a blend of two or more of the above polymers may also be used.

A plastic film made of a transparent thermoplastic resin material can be preferably employed as the base film. Among the plastic films, it is more preferable to use a polyester film. Here, the polyester film is a polyester polymer material (polyester resin) having a main skeleton based on an ester bond, such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate, etc., as the main resin component. say something Such a polyester film has favorable properties as a substrate film for a surface protection film, such as excellent optical properties and dimensional stability, but also has a property of being easily charged as it is.

Various additives such as antioxidants, ultraviolet absorbers, plasticizers, colorants (pigments, dyes, etc.) may be added to the resin material constituting the base film, if necessary. For example, known or commonly used surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, application of a primer may be applied. Such a surface treatment may be, for example, a treatment for enhancing the adhesion between the base film and the pressure-sensitive adhesive layer (the anchoring property of the pressure-sensitive adhesive layer).

In the pressure-sensitive adhesive sheet (surface protective film) of the present invention, a plastic film that has undergone antistatic treatment can be used as the base film. The use of the base film is preferable because the pressure-sensitive adhesive sheet itself can be prevented from being charged when it is peeled off. In addition, the base film is a plastic film, and by subjecting the plastic film to an antistatic treatment, the adhesive sheet itself can be reduced in static charge, and a sheet having excellent antistatic ability to the adherend can be obtained. The method for imparting the antistatic function is not particularly limited, and conventionally known methods can be used. Examples thereof include a method of applying a contained conductive resin, a method of depositing or plating a conductive substance, and a method of kneading an antistatic agent or the like.

The thickness of the base film is usually 5 to 200 μm, preferably about 10 to 100 μm. When the thickness of the base film is within the above range, the workability of laminating the film to an adherend and the workability of peeling from the adherend are excellent, which is preferable.

The pressure-sensitive adhesive sheet disclosed herein can also be implemented in a mode containing other layers in addition to the base film and the pressure-sensitive adhesive layer. Examples of the other layer include an antistatic layer and an undercoat layer (anchor layer) that enhances the anchoring property of the pressure-sensitive adhesive layer.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention can be used without particular limitation as long as it contains an adhesive polymer having adhesiveness, and a pressure-sensitive adhesive layer can be formed from the pressure-sensitive adhesive composition. Examples of the adhesive composition that can be used include acrylic adhesives, urethane adhesives, synthetic rubber adhesives, natural rubber adhesives, silicone adhesives, and the like. The adhesive polymer is at least one selected from the group consisting of (meth)acrylic polymers, urethane polymers, and silicone polymers, acrylic adhesives containing (meth)acrylic polymers, urethane and a urethane-based pressure-sensitive adhesive containing a silicone-based polymer, and those that use (contain) at least one selected from the group consisting of a silicone-based pressure-sensitive adhesive containing a silicone-based polymer are more preferable, and particularly preferably the adhesiveness It is to use an acrylic pressure-sensitive adhesive that uses a (meth)acrylic polymer that is a polymer.

When the pressure-sensitive adhesive layer uses an acrylic pressure-sensitive adhesive, the (meth)acrylic polymer, which is the pressure-sensitive adhesive polymer that constitutes the acrylic pressure-sensitive adhesive, contains an alkyl having 1 to 14 carbon atoms as a constituent monomer. A (meth)acrylic monomer having a group can be used as the main monomer. As the (meth)acrylic monomer, one or two or more can be used. By using the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it becomes easy to control the peeling force (adhesive force) to the adherend (protected object) to be low, and easy peeling. A pressure-sensitive adhesive sheet (surface protective film) with excellent adhesion and removability can be obtained. In the present invention, (meth)acrylic polymer means acrylic polymer and/or methacrylic polymer, and (meth)acrylate means acrylate and/or methacrylate.

Specific examples of the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, ) 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. be done.

Among them, when the adhesive sheet of the present invention is used as a surface protection film, n-butyl (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, (Meth)acrylic monomers having an alkyl group of 4 to 14 carbon atoms such as n-tetradecyl (meth)acrylate are preferred. In particular, by using a (meth)acrylic monomer having an alkyl group of 4 to 14 carbon atoms, it becomes easy to control the peeling force (adhesive force) to the adherend to be low, and the removability is excellent. becomes.

In particular, it is preferable to contain 50% by mass or more of a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms with respect to 100% by mass of the total amount of monomer components constituting the (meth)acrylic polymer. , more preferably 80% by mass or more, still more preferably 85 to 99.9% by mass, and most preferably 90 to 99% by mass. If it is less than 50% by mass, the appropriate wettability of the pressure-sensitive adhesive composition and the cohesive strength of the pressure-sensitive adhesive layer will deteriorate, which is not preferable.

Further, in the adhesive composition of the present invention, the (meth)acrylic polymer preferably contains a hydroxyl group-containing (meth)acrylic monomer as a raw material monomer. One or two or more of the hydroxyl group-containing (meth)acrylic monomers may be used. By using the hydroxyl group-containing (meth)acrylic monomer, it becomes easier to control the cross-linking of the pressure-sensitive adhesive composition, and as a result, the balance between the improvement of wettability due to flow and the reduction of peeling force (adhesive force) during peeling can be achieved. easier to control.

Examples of the hydroxyl group-containing (meth)acrylic monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate. , 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl acrylate, N-methylol (meth)acrylamide, and the like. . In particular, it is preferable to use a hydroxyl group-containing (meth)acrylic monomer having an alkyl group with 4 or more carbon atoms because it facilitates easy peeling during high-speed peeling.

The hydroxyl group-containing (meth)acrylic monomer preferably contains 25% by mass or less, more preferably 20% by mass or less, relative to the total amount of 100% by mass of the monomer components constituting the (meth)acrylic polymer. , more preferably 0.1 to 15% by mass, most preferably 1 to 10% by mass. Within the above range, the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive strength of the resulting pressure-sensitive adhesive layer can be easily controlled, which is preferable.

In addition, as other polymerizable monomer components, since it is easy to balance adhesive performance, Tg is set to 0 ° C. or less (usually -100 ° C. or more), and the glass transition temperature and peeling of the (meth) acrylic polymer A polymerizable monomer or the like for adjusting the properties can be used within a range that does not impair the effects of the present invention.

Other polymerizable monomers other than the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms and the hydroxyl group-containing (meth)acrylic monomer used in the (meth)acrylic polymer include: A carboxyl group-containing (meth)acrylic monomer can be used. By using the carboxyl group-containing (meth)acrylic monomer, it is possible to suppress the increase in the adhesive strength of the adhesive layer (adhesive sheet) over time, removability, adhesive strength increase prevention, and workability. Excellent for In addition, the cohesive force of the pressure-sensitive adhesive layer is excellent, and the shear force is also excellent, which is preferable.

Examples of the carboxyl group-containing (meth)acrylic monomer include (meth)acrylic acid, carboxylethyl (meth)acrylate, and carboxylpentyl (meth)acrylate.

The carboxyl group-containing (meth)acrylic monomer is preferably 0 to 5% by mass, preferably 0 to 3% by mass, based on the total amount of 100% by mass of the monomer components constituting the (meth)acrylic polymer. is more preferable, 0 to 2% by mass is more preferable, and 0 to 1% by mass is most preferable. Within the above range, the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive strength of the resulting pressure-sensitive adhesive layer can be easily controlled, which is preferable.

Further, when the hydroxyl group-containing (meth)acrylic monomer and the carboxyl group-containing (meth)acrylic monomer are used in combination, relative to 100% by mass of the total monomer component constituting the (meth)acrylic polymer , preferably contains 0.005 to 0.1% by mass of the carboxyl group-containing (meth)acrylic monomer. By adjusting the amount within the above range, it is effective to obtain a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) which is further excellent in removability and prevention of increase in pressure-sensitive adhesive strength.

Furthermore, the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the hydroxyl group-containing (meth)acrylic monomer, and the carboxyl group-containing (meth)acrylic monomer used in the (meth)acrylic polymer Polymerizable monomers other than the monomers may be used without particular limitation as long as they do not impair the properties of the present invention. For example, cohesion and heat resistance improving components such as cyano group-containing monomers, vinyl ester monomers, and aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, and N-acryloylmorpholine. , a component having a functional group acting as a base point for cross-linking or improving peeling force (adhesive force), such as a vinyl ether monomer, can be used as appropriate. Among them, cyano group-containing monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, and nitrogen-containing monomers such as N-acryloylmorpholine are preferably used. By using a nitrogen-containing monomer, it is possible to secure an appropriate peeling force (adhesive force) that does not cause lifting or peeling, and furthermore, it is possible to obtain an adhesive sheet (surface protective film) excellent in shearing force, which is useful. . One or two or more of these polymerizable monomers can be used.

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

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N,N-dimethylacrylamide, N,N-dimethylmethacrylamide, N,N-diethylacrylamide, N,N-diethyl methacrylamide, N,N'-methylenebisacrylamide, N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, diacetoneacrylamide and the like.

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

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

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

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene and other substituted styrenes.

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

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

In the present invention, other polymerizable monomers other than (meth)acrylic monomers having an alkyl group having 1 to 14 carbon atoms, hydroxyl group-containing (meth)acrylic monomers, and carboxyl group-containing (meth)acrylic monomers are It is preferably from 0 to 50% by mass, more preferably from 0 to 20% by mass, based on 100% by mass of the total amount of the monomer components constituting the (meth)acrylic polymer. The other polymerizable monomers can be appropriately adjusted in order to obtain desired properties.

The (meth)acrylic polymer may further contain an alkylene oxide group-containing reactive monomer as a monomer component.

Further, the average added mole number of oxyalkylene units in the alkylene oxide group-containing reactive monomer is preferably 1 to 40, more preferably 3 to 40, from the viewpoint of compatibility with the oxyalkylene group-containing compound. is more preferred, 4 to 35 is even more preferred, and 5 to 30 is particularly preferred. When the average number of added moles is 1 or more, there is a tendency that the effect of reducing contamination of the adherend (object to be protected) can be efficiently obtained. On the other hand, when the average added mole number is more than 40, the interaction with the oxyalkylene group-containing compound is large, and the viscosity of the pressure-sensitive adhesive composition increases, which tends to make coating difficult, which is not preferable. The terminal of the oxyalkylene chain may be a hydroxyl group as it is or may be substituted with another functional group.

The alkylene oxide group-containing reactive monomer may be used alone, or two or more may be mixed and used, but the content as a whole is the total amount of the monomer components of the (meth)acrylic polymer It is preferably from 0 to 20% by mass, more preferably from 0 to 10% by mass. If the content of the alkylene oxide group-containing reactive monomer exceeds 20% by mass, the staining property of the adherend deteriorates, which is not preferable.

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

Further, it is more preferable that the alkylene oxide group-containing reactive monomer is a reactive monomer having an ethylene oxide group. By using a (meth)acrylic polymer containing a reactive monomer having an ethylene oxide group as a base polymer, the compatibility between the base polymer and fluorine-based oligomers, ionic compounds, and oxyalkylene group-containing compounds is improved, and the adherend is improved. Bleeding to is suitably suppressed, and a low-staining pressure-sensitive adhesive composition can be obtained.

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

Specific examples of the (meth)acrylic acid alkylene oxide adduct include 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, methoxypolyethyleneglycol (meth)acrylate, ethoxypolyethyleneglycol (meth)acrylate, butoxypolyethyleneglycol (meth)acrylate, octoxypolyethyleneglycol (meth)acrylate, lauroxypolyethylene Glycol (meth)acrylate, stearoxypolyethyleneglycol (meth)acrylate, phenoxypolyethyleneglycol (meth)acrylate, methoxypolypropyleneglycol (meth)acrylate, octoxypolyethyleneglycol-polypropyleneglycol (meth)acrylate and the like.

Further, 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, a cationic reactive surfactant, and the like. is given.

The (meth)acrylic polymer preferably has a weight average molecular weight (Mw) of 100,000 to 5,000,000, more preferably 200,000 to 4,000,000, still more preferably 300,000 to 3,000,000, and most preferably 300,000 to 950,000. is. When the weight-average molecular weight is less than 100,000, the cohesive force of the pressure-sensitive adhesive layer is reduced, which tends to cause adhesive residue. On the other hand, when the weight-average molecular weight exceeds 5,000,000, the fluidity of the polymer decreases, and the wettability of the adherend (e.g., polarizing plate) becomes insufficient, resulting in adhesion between the adherend and the pressure-sensitive adhesive sheet (surface protective film). It tends to cause blisters that occur between the adhesive layer. In addition, a weight average molecular weight means the thing obtained by measuring by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the (meth)acrylic polymer is preferably 0° C. or lower, more preferably -10° C. or lower (usually -100° C. or higher). When the glass transition temperature is higher than 0° C., the polymer is difficult to flow, for example, the wettability of the polarizing plate, which is an optical member, is insufficient, resulting in a gap between the polarizing plate and the adhesive layer of the adhesive sheet (surface protective film). It tends to cause blisters that occur. In particular, by setting the glass transition temperature to −61° C. or lower, it becomes easier to obtain a pressure-sensitive adhesive layer that is excellent in wettability to a polarizing plate and easy peelability. Incidentally, the glass transition temperature of the (meth)acrylic polymer can be adjusted within the above range by appropriately changing the monomer components and the composition ratio to be used.

The method for polymerizing the (meth)acrylic polymer is not particularly limited, and can be polymerized by known methods such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. Solution polymerization is a more preferable mode from the viewpoint of properties such as low contamination to the adherend (object to be protected). Moreover, the polymer obtained may be a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, or the like.

When using a urethane-based pressure-sensitive adhesive for the pressure-sensitive adhesive layer, any appropriate urethane-based pressure-sensitive adhesive can be adopted. Such a urethane-based pressure-sensitive adhesive preferably includes a urethane-based polymer, which is an adhesive polymer obtained by reacting a polyol with a polyisocyanate compound. Examples of polyols include polyether polyols, polyester polyols, polycarbonate polyols, polycaprolactone polyols, and the like. Examples of polyisocyanate compounds include diphenylmethane diisocyanate, tolylene diisocyanate, and hexamethylene diisocyanate.

When using a silicone-based pressure-sensitive adhesive for the pressure-sensitive adhesive layer, any appropriate silicone-based pressure-sensitive adhesive can be adopted. As such a silicone-based pressure-sensitive adhesive, one obtained by blending or aggregating a silicone-based polymer, which is an adhesive polymer, can be preferably employed.

Examples of the silicone-based pressure-sensitive adhesive include addition reaction-curable silicone-based pressure-sensitive adhesives and peroxide-curable silicone-based pressure-sensitive adhesives. Among these silicone-based pressure-sensitive adhesives, addition reaction-curable silicone-based pressure-sensitive adhesives are preferred because they do not use peroxides (such as benzoyl peroxide) and do not generate decomposition products.

As the curing reaction of the addition reaction-curable silicone-based pressure-sensitive adhesive, for example, when obtaining a polyalkylsilicone-based pressure-sensitive adhesive, a method of curing a polyalkylhydrogensiloxane composition with a platinum catalyst is generally used.

<Fluorine-based oligomer>
The pressure-sensitive adhesive composition of the present invention is characterized by containing a pressure-sensitive adhesive polymer, a fluorine-based oligomer having a weight average molecular weight of 3500 or more, and an ionic compound. By including a fluorine-based oligomer having a weight average molecular weight of 3500 or more in the pressure-sensitive adhesive composition, when the resulting pressure-sensitive adhesive layer (adhesive sheet) is laminated to an optical member such as a polarizing plate, fluorine in the fluorine-based oligomer The low surface free energy of the part exerts a light release effect, and the fluorine-based oligomer functions as a tackifying resin, improving adhesion and suppressing slippage, lifting, and peeling of the surface protective film. In other words, it is possible to achieve both easy peelability (removability) and adhesiveness, which is a preferred embodiment. Further, the pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 3 on at least one side of the base film, and the inside of the pressure-sensitive adhesive layer, And/or it is preferable that the fluorine-based oligomer is present on the surface. In addition, the "inside" of the pressure-sensitive adhesive layer refers to, for example, the case of being contained in the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer is formed using the pressure-sensitive adhesive composition containing the fluorine-based oligomer. . Further, the "surface" of the pressure-sensitive adhesive layer is, for example, the case where the fluorine-based oligomer contained in the pressure-sensitive adhesive layer containing the fluorine-based oligomer is present (exposed) on the surface of the pressure-sensitive adhesive layer, or the surface of the pressure-sensitive adhesive layer. In order to protect the surface of the pressure-sensitive adhesive layer, the fluorine-based oligomer is applied (laminated) in advance on the surface of the separator to be adhered, and when the separator is adhered to the pressure-sensitive adhesive layer, the fluorine is removed from the separator surface. It refers to the case where the system oligomer is transferred (migrated) to the pressure-sensitive adhesive layer surface.

The weight average molecular weight (Mw) of the fluorine-based oligomer is 3,500 or more, preferably 5,000 or more, more preferably 10,000 or more, and still more preferably 20,000 or more. When the weight-average molecular weight of the fluorine-based oligomer is 3500 or more, the function as a tackifier resin is more exhibited, the adhesiveness is improved, and the surface protective film can be prevented from slipping (displacement), lifting, peeling, and the like. Furthermore, when the weight-average molecular weight is 20,000 or more, foaming can be suppressed when the pressure-sensitive adhesive (composition) is blended, and the appearance after the pressure-sensitive adhesive is applied is excellent, which is preferable. The upper limit of the weight average molecular weight (Mw) of the fluorine-based oligomer is preferably 200,000 or less, more preferably 100,000 or less. By making it 200,000 or less, the fluorine-based oligomer tends to segregate on the surface, and the easy peeling effect can be exhibited more easily, which is preferable.

Specific examples of the fluorine-based oligomer include commercially available products with trade names Megafac F-251, F-253, F-281, F-410, F-430, F-444, F-477, F -510, F-511, F-551, F-552, F-553, F-554, F-555, F-556, F-557, F-558, F-559, F-560, F-561 , F-562, F-563, F-565, F-568, F-569, F-570, F-571, F-572 (manufactured by DIC), Surflon S-611, S-651, S -386 (manufactured by AGC Seimi Chemical Co., Ltd.), Futergent 610FM, 710FL, 710FM, 710FS, 730FL, 730LM (manufactured by Neos Co., Ltd.). These compounds may be used alone or in combination of two or more.

The content of the fluorine-based oligomer is based on 100 parts by mass of the adhesive polymer (base polymer, e.g., (meth)acrylic polymer, urethane polymer, silicone polymer, etc.) constituting the adhesive composition. , Preferably 0.01 to 10 parts by mass, more preferably 0.02 to 7.5 parts by mass, still more preferably 0.03 to 5.5 parts by mass, most preferably 0.04 to 4.8 parts by mass Department. Within the above range, the pressure-sensitive adhesive sheet of the present invention can be prevented from slipping (displacement), lifting, peeling, etc. after being bonded to an optical member or the like, and is excellent in light releasability, which is preferable. Further, in order to satisfy stain resistance, the content of the fluorine-based oligomer is preferably 0.01 to 5.5 parts by mass with respect to 100 parts by mass of the adhesive polymer.

<Ionic compound>
It is preferable that the pressure-sensitive adhesive composition contains an ionic compound, and as the ionic compound, at least one of an alkali metal salt, an ionic liquid, and an ionic group-containing silicone is used. By containing at least one of these ionic compounds, it is possible to impart excellent antistatic properties and release electrification properties.

Since the alkali metal salt has a high ion dissociation property, it is preferable in terms of exhibiting excellent antistatic performance even when added in a very small amount. Examples of the alkali metal salts include cations composed of Li ⁺ , Na ⁺ , and K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , and SCN. ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , C ₉ H ₁₉ COO ⁻ , CF ₃ COO ⁻ , C ₃ F ₇ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₄ F ₉ SO ₃ ⁻ , C ₂ H ₅ OSO ₃ ⁻ , C ₆ H ₁₃ OSO ₃ ⁻ , C ₈ H ₁₇ OSO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F(HF) _n ⁻ , (CN) ₂ N ⁻ , (CF ₃ SO ₂ )(CF ₃ CO)N ⁻ , (CH ₃ ) ₂ PO ₄ ⁻ , (C ₂ H ₅ ) ₂ PO ₄ ⁻ , CH ₃ (OC ₂ H ₄ ) ₂ OSO ₃ ⁻ , C ₆ H ₄ (CH ₃ )SO ₃ ⁻ , (C ₂ F ₅ ) ₃ PF ₃ ⁻ , CH ₃ CH(OH)COO ⁻ , and (FSO ₂ ) ₂ A metal salt composed of an anion consisting of N 2 ⁻ is preferably used. More preferably LiBr, LiI, _LiBF4 , _LiPF6 , _LiSCN , LiClO4, _{LiCF3SO3 ,} Li _{( CF3SO2} )2N, Li _{( C2F5SO2} ) _2N , _{Li ( FSO2} )2N, Li _{( CF3SO2} ) _{3C , more} preferably _{LiCF3SO3 ,} Li _{( CF3SO2} )2N, Li _{( C2F5SO2} ) _2N , Li _{( C3F7SO2} )2N, Li _{( C4F9SO2} )2N _, Li _{( FSO2} ) _{2N , Li ( CF3SO2} ) _{3C are} used. These alkali metal salts may be used alone or in combination of two or more.

The ionic liquid is preferably composed of an organic cation component represented by the following formulas (A) to (E) and an anion component. By using an ionic liquid having a melting point of 100° C. or lower among these cation-containing ionic liquids, an even more excellent antistatic property can be obtained.

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

R _d in the formula (B) represents a hydrocarbon group having 2 to 20 carbon atoms, and may be a functional group in which a part of the hydrocarbon group _is substituted with a hetero atom _. , and R _g may be the same or different and represent hydrogen or a hydrocarbon group having 1 to 16 carbon atoms, and may be a functional group in which a portion of the hydrocarbon group is substituted with a hetero atom.

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

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

R 1 _P in the formula (E) represents a hydrocarbon group having 1 to 18 carbon atoms, and may be a functional group in which a part of the hydrocarbon group is substituted with a hetero atom.

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

Specific examples include 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl -3-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidinium cation cation, 1-methyl-1-butylpyrrolidinium cation, 1-methyl-1-pentylpyrrolidinium cation, 1-methyl-1-hexylpyrrolidinium cation, 1-methyl-1-heptylpyrrolidinium cation Cation, 1-ethyl-1-propylpyrrolidinium cation, 1-ethyl-1-butylpyrrolidinium cation, 1-ethyl-1-pentylpyrrolidinium cation, 1-ethyl-1-hexylpyrrolidinium cation , 1-ethyl-1-heptylpyrrolidinium cation, 1,1-dipropylpyrrolidinium cation, 1-propyl-1-butylpyrrolidinium cation, 1,1-dibutylpyrrolidinium cation, pyrrolidinium-2 -one cation, 1-propylpiperidinium cation, 1-pentylpiperidinium cation, 1,1-dimethylpiperidinium cation, 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-propylpiperidinium cation peridinium cation, 1-methyl-1-butylpiperidinium cation, 1-methyl-1-pentylpiperidinium cation, 1-methyl-1-hexylpiperidinium cation, 1-methyl-1-heptylpiperidinium cation cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1-ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation , 1-ethyl-1-heptylpiperidinium cation, 1,1-dipropylpiperidinium cation, 1-propyl-1-butylpiperidinium cation, 1,1-dibutylpiperidinium cation, 2-methyl -1-pyrroline cation, 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole cation, N-ethyl-N-methylmorpholinium cation, etc. be done.

Examples of cations represented by formula (B) include imidazolium cations, tetrahydropyrimidinium cations, and dihydropyrimidinium cations.

Specific examples include, for example, 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1- xyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazolium cation lithium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3 -dimethylimidazolium cation, 1-(2-methoxyethyl)-3-methylimidazolium cation, 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl- 1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl- 1,4,5,6-tetrahydropyrimidinium cation, 1,3-dimethyl-1,4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2, 3-trimethyl-1,4-dihydropyrimidinium cation, 1,2,3-trimethyl-1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,6-dihydropyrimidinium cation, and the like.

Examples of cations represented by formula (C) include pyrazolium cations and pyrazolinium cations.

Specific examples include 1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation, and 1-ethyl-2,3,5-trimethylpyrazolium cation. , 1-propyl-2,3,5-trimethylpyrazolium cation, 1-butyl-2,3,5-trimethylpyrazolium cation, 1-ethyl-2,3,5-trimethylpyrazolinium cation, 1 -propyl-2,3,5-trimethylpyrazolinium cation, 1-butyl-2,3,5-trimethylpyrazolinium cation, and the like.

Examples of cations represented by formula (D) include tetraalkylammonium cations, trialkylsulfonium cations, tetraalkylphosphonium cations, and alkyl groups partially substituted with alkenyl groups, alkoxyl groups, and epoxy groups. I can give you something.

Specific examples include tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptylammonium cation, triethylmethylammonium cation, tributylethylammonium cation, and trimethyldecylammonium cation. , N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium cation, glycidyltrimethylammonium cation, trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutyl Ethylsulfonium cation, dimethyldecylsulfonium cation, tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium cation, tetrahexylphosphonium cation, tetraoctylphosphonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, diallyldimethyl ammonium cation, tributyl-(2-methoxyethyl)phosphonium cation, and the like. Among them, asymmetric cations such as triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation. Tetraalkylammonium cation, trialkylsulfonium cation, tetraalkylphosphonium cation, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N,N -dimethyl-N-ethyl-N-propylammonium cation, N,N-dimethyl-N-ethyl-N-butylammonium cation, N,N-dimethyl-N-ethyl-N-pentylammonium cation, N,N-dimethyl -N-ethyl-N-hexylammonium cation, N,N-dimethyl-N-ethyl-N-heptylammonium cation, N,N-dimethyl-N-ethyl-N-nonylammonium cation, N,N-dimethyl-N , N-dipropylammonium cation, N,N-diethyl-N-propyl-N-butylammonium cation, N,N-dimethyl-N-propyl-N-pentylammonium cation, N,N-dimethyl-N-propyl- N-hexylammonium cation, N,N-dimethyl-N-propyl-N-heptylammonium cation, N,N-dimethyl-N-butyl-N-hexylammonium cation, N,N-diethyl-N-butyl-N- heptylammonium cation, N,N-dimethyl-N-pentyl-N-hexylammonium cation, N,N-dimethyl-N,N-dihexylammonium cation, trimethylheptylammonium cation, N,N-diethyl-N-methyl-N -propylammonium cation, N,N-diethyl-N-methyl-N-pentylammonium cation, N,N-diethyl-N-methyl-N-heptylammonium cation, N,N-diethyl-N-propyl-N-pentyl ammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, N,N- Dipropyl-N-methyl-N-ethylammonium cation, N,N-dipropyl-N-methyl-N-pentylammonium cation, N,N-dipropyl-N-butyl-N-hexylammonium cation, N,N-dipropyl- N,N-dihexylammonium cation, N,N-dibutyl-N-methyl-N-pentylammonium cation, N,N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation, N-methyl- The N-ethyl-N-propyl-N-pentylammonium cation is preferably used.

Examples of cations represented by formula (E) include sulfonium cations. Further, specific examples of R 2 _P in the formula (E) include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, octadecyl group and the like.

_On the other _hand ^, the ^{anion component} is not ^particularly limited as long as it ^satisfies the ^formation of an _{ionic liquid} . ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₄ F ₉ SO ₃ ⁻ , (CF ₃ SO ₂ ) _2N- ^, _{( C2F5SO2 ) 2N-} ^, _{( C3F7SO2} ) _{2N- , ( C4F9SO2} ⁾ _2N- ^, _{( CF3SO2 ) 3C-} ^, AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F(HF) _n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ )(CF ₃ CO)N ⁻ , C ₉ H ₁₉ COO ⁻ , (CH ₃ ) ₂ PO ₄ ⁻ , (C ₂ H ₅ ) ₂ PO ₄ ⁻ , CH ₃ OSO ₃ ⁻ , C ₂ H ₅ OSO ₃ ⁻ , C ₄ H ₉ OSO ₃ ⁻ , C ₆ H ₁₃ OSO ₃ ⁻ , C ₈ H ₁₇ OSO ₃ ⁻ , CH ₃ (OC ₂ H ₄ ) ₂ OSO ₃ ⁻ , C _{6H4 ( CH3} ⁾ _{SO3- , ( C2F5} ) _3PF3- ^, _CH3CH (OH)COO- ^, ( _FSO2 ) _2N- ^, B(CN) _4- ^, C(CN) ₃ ⁻ , N(CN) ₂ ⁻ , p-toluenesulfonate anion, 2-(2-methoxyethyl)ethylsulfate anion and the like can be used.

These ionic liquids may be used alone or in combination of two or more.

なお、上記式（１）中のＲ_１～Ｒ_４は、同一でも異なっていてもよく、炭素数１～１０のアルキル基、アルコキシ基、アリール基、アリサイクリック基、フッ素置換アルキル基、イオン性基のいずれかを含み、Ｒ_１～Ｒ_４のうち1つ以上にイオン性基を含む。ｎは０～１００の整数である。 Moreover, as the ionic group-containing silicone, one represented by the following formula (1) is preferable.

In addition, R ₁ to R ₄ in the above formula (1) may be the same or different, and an alkyl group having 1 to 10 carbon atoms, an alkoxy group, an aryl group, an alicyclic group, a fluorine-substituted alkyl group, an ion and one or more of R ₁ to R ₄ contain an ionic group. n is an integer from 0 to 100;

As the ionic group contained in one or more of R ₁ to R ₄ , an ionic group having an ammonium cationic group or a phosphonium cationic group is preferable. Among them, one or more of R ₁ to R ₄ preferably consist of a cation structure represented by the following formula (a) or (b) and an anion component, or represented by (c) or (d) It is preferably a zwitterionic structure.

上記式（ａ）中のＲ_５～Ｒ_７は、同一でも異なっていてもよく、炭素数１～１０のアルキル基、アリール基、フッ素置換アルキル基のいずれかを示す。ｍは１～１０の整数である。

R ₅ to R ₇ in the above formula (a) may be the same or different and represent any one of an alkyl group having 1 to 10 carbon atoms, an aryl group and a fluorine-substituted alkyl group. m is an integer from 1 to 10;

上記式（ｂ）中のＲ_８～Ｒ_１０は、同一でも異なっていてもよく、炭素数１～１０のアルキル基、アリール基、フッ素置換アルキル基のいずれかを示す。ｍは１～１０の整数である。

R ₈ to R ₁₀ in the above formula (b) may be the same or different and represent any one of an alkyl group having 1 to 10 carbon atoms, an aryl group and a fluorine-substituted alkyl group. m is an integer from 1 to 10;

On the other hand, the anion component is not particularly limited, and examples thereof include Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₄ F ₉ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F(HF) _n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ )( CF ₃ CO)N ⁻ , C ₉ H ₁₉ COO ⁻ , (CH ₃ ) ₂ PO ₄ ⁻ , (C ₂ H ₅ ) ₂ PO ₄ ⁻ , C ₂ H ₅ OSO ₃ ⁻ , C ₆ H ₁₃ OSO ₃ ⁻ , ^C8H17OSO3- _{, CH3} ⁽ _OC2H4 ⁾ _{2OSO3- , C6H4 ( CH3} ⁾ _{SO3- , ( C2F5} ) _{3PF3- , CH3CH ( OH} ) COO ⁻ , (FSO ₂ ) ₂ N ⁻ and the like are used.

上記式（ｃ）中のＲ_１１、Ｒ_１２は、同一でも異なっていてもよく、炭素数１～１０のアルキル基、アリール基、フッ素置換アルキル基のいずれかを示し、Ｒ_１１、Ｒ_１２は環を形成していてもよく、その場合はアルキレン基を表す。ｍは１～１０の整数、ｐは１～６の整数である。

R ₁₁ and R ₁₂ in the above formula (c) may be the same or different and each represents an alkyl group having 1 to 10 carbon atoms, an aryl group or a fluorine-substituted alkyl group, and R ₁₁ and R ₁₂ are It may form a ring, in which case it represents an alkylene group. m is an integer of 1-10, p is an integer of 1-6.

上記式（ｄ）中のＲ_１３、Ｒ_１４は、同一でも異なっていてもよく、炭素数１～１０のアルキル基、アリール基、フッ素置換アルキル基のいずれかを示し、Ｒ_１３、Ｒ_１４は環を形成してもよく、その場合はアルキレン基を表す。ｍは１～１０の整数、ｐは１～６の整数である。

R ₁₃ and R ₁₄ in the above formula (d) may be the same or different and each represents an alkyl group having 1 to 10 carbon atoms, an aryl group or a fluorine-substituted alkyl group, and R ₁₃ and R ₁₄ are It may form a ring, in which case it represents an alkylene group. m is an integer of 1-10, p is an integer of 1-6.

Since such ionic group-containing silicones contain silicone chains, the low surface free energy of the silicone chains allows the pressure-sensitive adhesive layer to be attached to the surface of an adherend (e.g., polarizing plate) and stored in a high-temperature environment. Even when the ionic group-containing silicone does not permeate into the adherend (from the adherend surface to the inside of the adherend), it tries to stay on the adhesive layer surface, so the peel electrification is maintained even over time. The properties are stable, the antistatic performance is maintained for a long period of time, and it can be suitably used as an antistatic agent.

Specific examples of the ionic group-containing silicone include commercially available products under the trade names of X-40-2450 and X-40-2750 (manufactured by Shin-Etsu Chemical Co., Ltd.). These compounds may be used alone or in combination of two or more.

The content of the ionic compound is based on 100 parts by weight of the adhesive polymer (base polymer, such as (meth)acrylic polymer, urethane polymer, silicone polymer, etc.) constituting the adhesive composition. , Preferably 0.01 to 10 parts by mass, more preferably 0.02 to 7.5 parts by mass, still more preferably 0.03 to 5.5 parts by mass, most preferably 0.04 to 4.8 parts by mass Department. When it is within the above range, the pressure-sensitive adhesive sheet of the present invention can easily achieve both antistatic properties and suppression of slippage (displacement), which is preferable.

<Oxyalkylene group-containing compound>
The pressure-sensitive adhesive composition of the present invention preferably contains an oxyalkylene group-containing compound, more preferably contains an organopolysiloxane having an oxyalkylene chain, and contains an organopolysiloxane having an oxyalkylene main chain. is even more preferred. It is presumed that the use of the organopolysiloxane lowers the surface free energy of the pressure-sensitive adhesive surface and realizes easy release.

なお、上記式（２）中、Ｒ_１及び／又はＲ_２は、炭素数１～６のオキシアルキレン鎖を有し、前記オキシアルキレン鎖中のアルキレン基は、直鎖又は分岐していてもよく、前記オキシアルキレン鎖の末端が、アルコキシ基、又は、ヒドロキシル基であってもよい。また、Ｒ_１又はＲ_２のいずれか一方が、ヒドロキシル基でもよく、又は、アルキル基、アルコキシ基であってもよく、前記アルキル基、アルコキシ基の一部が、ヘテロ原子で置換された官能基であってもよい。ｎは、１～３００の整数である。 As the organopolysiloxane, any known organopolysiloxane having a polyoxyalkylene main chain can be appropriately used, but the organopolysiloxane represented by the following formula (2) is preferable.

In the above formula (2), R ₁ and / or R ₂ has an oxyalkylene chain having 1 to 6 carbon atoms, and the alkylene group in the oxyalkylene chain may be linear or branched. , the terminal of the oxyalkylene chain may be an alkoxy group or a hydroxyl group. Further, either one of R ₁ or R ₂ may be a hydroxyl group, an alkyl group, or an alkoxy group, and a portion of the alkyl group or alkoxy group is a functional group substituted with a hetero atom. may be n is an integer from 1 to 300;

The organopolysiloxane used has a siloxane-containing portion (siloxane portion) as a main chain and an oxyalkylene chain bonded to the end of the main chain. By using the organosiloxane having the oxyalkylene chain, it is presumed that compatibility with (meth)acrylic polymers, fluorine-based oligomers, ionic compounds, etc. is balanced and easy release is realized. .

Moreover, as the organopolysiloxane in the present invention, for example, the following constitutions can be used. Specifically, R ₁ and / or R ₂ in the formula has an oxyalkylene chain containing a hydrocarbon group having 1 to 6 carbon atoms, and the oxyalkylene chain includes an oxymethylene group, an oxyethylene group, an oxy A propylene group, an oxybutylene group, and the like can be mentioned, and among them, an oxyethylene group and an oxypropylene group are preferable. When both R ₁ and R ₂ have an oxyalkylene chain, they may be the same or different.

Further, the hydrocarbon group of the oxyalkylene chain may be linear or branched.

Furthermore, the terminal of the oxyalkylene chain may be an alkoxy group or a hydroxyl group, but among them, an alkoxy group is more preferable. When a separator is attached to the adhesive layer surface for the purpose of protecting the adhesive surface, hydroxyl-terminated organopolysiloxane interacts with the separator, causing adhesion (peeling) when the separator is peeled off from the adhesive layer surface. Power may increase.

Also, n is an integer of 1-300, preferably 10-200, more preferably 20-150. When n is within the above range, the compatibility with the base polymer is well balanced, which is a preferred embodiment. Furthermore, the molecule may have a reactive substituent such as a (meth)acryloyl group, an allyl group, or a hydroxyl group. The above organopolysiloxanes may be used alone, or two or more of them may be used in combination.

Specific examples of the organopolysiloxane having an oxyalkylene chain in the main chain include, for example, commercial products with trade names of X-22-4952, X-22-4272, X-22-6266, KF-6004, KF-889 (manufactured by Shin-Etsu Chemical Co., Ltd.), BY16-201, SF8427 (manufactured by Dow Corning Toray Co., Ltd.), IM22 (manufactured by Asahi Kasei Wacker Co., Ltd.), and the like. These compounds may be used alone or in combination of two or more.

なお、上記式（３）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は水素もしくは有機基、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 addition to the above-described organosiloxane having an oxyalkylene chain in the main chain (bonding), it is also possible to use an organosiloxane having an oxyalkylene chain in the side chain (bonding), and the side chain rather than the main chain can be used. It is a more preferred embodiment to use an organosiloxane having an oxyalkylene chain in . As the organopolysiloxane, an organopolysiloxane having a known polyoxyalkylene side chain can be appropriately used, but the organopolysiloxane represented by the following formula (3) is preferable.

In formula (3) above, 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, and m and n are integers of 0-1000. However, m and n cannot be 0 at the same time. a and b are integers from 0 to 100; However, a and b cannot be 0 at the same time. )

Moreover, as the organopolysiloxane in the present invention, for example, the following constitutions can be used. Specifically, R ₁ in the formula is a monovalent monovalent It is an organic group and each may have a substituent such as a hydroxyl group. R ₂ , R ₃ and R ₄ can be C 1-8 alkylene groups such as methylene, ethylene and propylene. 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 . R ₅ may be a monovalent organic group exemplified by an alkyl group such as methyl group, ethyl group and propyl group, or an acyl group such as acetyl group and propionyl group, each having a substituent such as hydroxyl group. may be These compounds may be used alone or in combination of two or more. Moreover, the molecule may have a reactive substituent such as a (meth)acryloyl group, an allyl group, or a hydroxyl group. Among the organosiloxanes having polyoxyalkylene side chains, organosiloxanes having hydroxyl group-terminated polyoxyalkylene side chains are presumed to facilitate well-balanced compatibility, and thus are preferred.

Specific examples of the organosiloxane having an oxyalkylene chain in the side chain include, for example, commercially available product names KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF -945, KF-640, KF-642, KF-643, KF-6022, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017, X-22 -2516 (manufactured by Shin-Etsu Chemical Co., Ltd.) SF8428, FZ-2162, SH3749, FZ-77, L-7001, FZ-2104, FZ-2110, L-7002, FZ-2122, FZ-2164, FZ-2203 , FZ-7001, SH8400, SH8700, SF8410, SF8422 (manufactured by Dow Corning Toray), TSF-4440, TSF-4441, TSF-4445, TSF-4450, TSF-4446, TSF-4452, TSF-4460 (manufactured by Momentive Performance Materials), BYK-333, BYK-307, BYK-377, BYK-UV3500 and BYK-UV3570 (manufactured by BYK-Chemie Japan). These compounds may be used alone or in combination of two or more.

The organosiloxane used in the present invention preferably has an HLB (Hydrophile-Lipophile Balance) value of 1-16, more preferably 3-14. If the HLB value is out of the above range, the staining property to the adherend is deteriorated, which is not preferable.

The pressure-sensitive adhesive composition may contain an oxyalkylene group-containing compound that does not contain organopolysiloxane. By including the above compound in the pressure-sensitive adhesive, it is possible to obtain a pressure-sensitive adhesive with even better wettability to adherends.

Specific examples of the oxyalkylene group-containing compound containing no organopolysiloxane include polyoxyalkylene alkylamines, polyoxyalkylene diamines, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, and polyoxyalkylene alkylphenyl ethers. , polyoxyalkylene alkyl ethers, polyoxyalkylene alkyl allyl ethers, polyoxyalkylene alkyl phenyl allyl ethers, and other nonionic surfactants; polyoxyalkylene alkyl ether sulfate salts, polyoxyalkylene alkyl ether phosphate salts, poly Anionic surfactants such as oxyalkylene alkylphenyl ether sulfate salts and polyoxyalkylene alkylphenyl ether phosphate salts; other cationic surfactants and amphoteric surfactants having polyoxyalkylene chains (polyalkylene oxide chains) Surfactants, polyether compounds having a polyoxyalkylene chain (including derivatives thereof), acrylic compounds having a polyoxyalkylene chain (including derivatives thereof), and the like. Also, a polyoxyalkylene chain-containing monomer may be blended as a polyoxyalkylene chain-containing compound. Such polyoxyalkylene chain-containing compounds may be used alone or in combination of two or more.

Specific examples of the polyether-based compound (polyether component) having a polyoxyalkylene chain include a block copolymer of polypropylene glycol (PPG)-polyethylene glycol (PEG), a block copolymer of PPG-PEG-PPG, PEG-PPG-PEG block copolymers and the like are included. Examples of derivatives of polyether compounds having a polyoxyalkylene chain include terminally etherified oxypropylene group-containing compounds (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.), terminally acetylated oxypropylene group-containing compounds (terminally acetylated PPG, etc.), and the like.

A specific example of the acrylic compound having a polyoxyalkylene chain is a (meth)acrylate polymer having an oxyalkylene group. As for the oxyalkylene group, the number of added moles of oxyalkylene units is preferably 1 to 50, more preferably 2 to 30, and even more preferably 2 to 20. Moreover, the terminal of the oxyalkylene chain may be substituted with an alkyl group, a phenyl group, or the like, or may be a hydroxyl group.

The (meth)acrylate polymer having an oxyalkylene group is preferably a polymer containing alkylene oxide (meth)acrylate as a monomer unit (component). Examples of ethylene glycol group-containing (meth)acrylates include methoxy-polyethylene glycol (meth) acrylate types such as methoxy-diethylene glycol (meth) acrylate and methoxy-triethylene glycol (meth) acrylate, ethoxy-diethylene glycol ( meth) acrylate, ethoxy-polyethylene glycol (meth) acrylate type such as ethoxy-triethylene glycol (meth) acrylate, butoxy-polyethylene glycol (meth) acrylate type such as butoxy-diethylene glycol (meth) acrylate, butoxy-triethylene glycol (meth) acrylate, etc. ) acrylate type, phenoxy-polyethylene glycol (meth) acrylate type such as phenoxy-diethylene glycol (meth) acrylate, phenoxy-triethylene glycol (meth) acrylate, 2-ethylhexyl-polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (meth) acrylate ) acrylate type, methoxy-polypropylene glycol (meth)acrylate type such as methoxy-dipropylene glycol (meth)acrylate, and the like.

Further, as the monomer units (components), monomer units (components) other than the alkylene oxide (meth)acrylate can be used. Specific examples of other monomer components include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, ) 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 ) Acrylate and/or methacrylate having an alkyl group having 1 to 14 carbon atoms such as acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate is mentioned.

Furthermore, other monomer units (components) than the (meth)acrylic acid alkylene oxide include carboxyl group-containing (meth)acrylates, phosphoric acid group-containing (meth)acrylates, cyano group-containing (meth)acrylates, and vinyl esters. , aromatic vinyl compound, acid anhydride group-containing (meth) acrylate, hydroxyl group-containing (meth) acrylate, amide group-containing (meth) acrylate, amino group-containing (meth) acrylate, epoxy group-containing (meth) acrylate, N- Acryloylmorpholine, vinyl ethers and the like can also be used as appropriate.

In a more preferred embodiment, the polyoxyalkylene chain-containing compound containing no organopolysiloxane is a compound having at least a portion of a (poly)ethylene oxide chain. By blending the (poly)ethylene oxide chain-containing compound, the compatibility between the base polymer and the fluorine-based oligomer or ionic compound is improved, bleeding to the adherend is suitably suppressed, and a low-staining pressure-sensitive adhesive. A composition is obtained. Among them, when a block copolymer of PPG-PEG-PPG is used, a pressure-sensitive adhesive excellent in low-staining property can be obtained. As the polyethylene oxide chain-containing compound, the weight of the (poly)ethylene oxide chain in the entire polyoxyalkylene chain-containing compound containing no organopolysiloxane is preferably 5 to 90% by mass, more preferably 5 to 85%. % by mass, more preferably 5 to 80% by mass, most preferably 5 to 75% by mass.

As the molecular weight of the polyoxyalkylene chain-containing compound containing no organopolysiloxane, a number average molecular weight (Mn) of 50,000 or less is suitable, preferably 200 to 30,000, more preferably 200 to 10,000, and usually of 200 to 5,000 are preferably used. If the Mn is more than 50,000, the compatibility with the acrylic polymer is lowered, and the pressure-sensitive adhesive layer tends to whiten. If Mn is much smaller than 200, contamination with the polyoxyalkylene compound may easily occur. Here, Mn refers to a polystyrene-equivalent value obtained by GPC (gel permeation chromatography).

Further, specific examples of commercially available polyoxyalkylene chain-containing compounds that do not contain organopolysiloxane include, for example, Adeka Pluronic 17R-4, Adeka Pluronic 25R-2 (all of which are manufactured by ADEKA), Latemul PD- 420, Latemul PD-420, Latemul PD-450, Emulgen 120 (manufactured by Kao Corporation), Aqualon HS-10, KH-10, Neugen EA-87, EA-137, EA-157, EA-167, EA-177 ( (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

The content of the oxyalkylene group-containing compound is 100 parts by mass of the adhesive polymer (base polymer, e.g., (meth)acrylic polymer, urethane polymer, silicone polymer, etc.) constituting the adhesive composition. is preferably 0.01 to 5.0 parts by mass, more preferably 0.02 to 2 parts by mass, still more preferably 0.03 to 1.6 parts by mass, most preferably 0.1 to 0.1 part by mass. 8 parts by mass. Within the above range, the pressure-sensitive adhesive sheet of the present invention easily achieves both smoothness (displacement) and easy peelability (removability), which is preferable.

<Crosslinking agent>
In the pressure-sensitive adhesive sheet (surface protection film) of the present invention, the pressure-sensitive adhesive composition preferably contains a cross-linking agent. Moreover, in this invention, it can be set as an adhesive layer using the said adhesive composition. For example, when the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth)acrylic polymer, the constituent units of the (meth)acrylic polymer, the composition ratio, the selection and addition ratio of the cross-linking agent, etc. By adjusting and crosslinking, it is possible to obtain a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) having more excellent heat resistance.

As the cross-linking agent used in the present invention, isocyanate compounds, epoxy compounds, melamine resins, aziridine derivatives, metal chelate compounds and the like may be used, and the use of isocyanate compounds is particularly preferred. Moreover, these compounds may be used individually and may be used in mixture of 2 or more types.

Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), dimer acid diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1, Alicyclic isocyanates such as 3-bis(isocyanatomethyl)cyclohexane, 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, aromatic isocyanates such as xylylene diisocyanate (XDI), and the isocyanate compounds Modified polyisocyanates modified with allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond, oxadiazinetrione bond and the like are included. For example, commercially available products include Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (manufactured by Takeda Pharmaceutical Co., Ltd.), Sumidule T80, Sumidule L, Desmodur N3400 (Sumika Bayer Urethane). (manufactured by Nippon Polyurethane Industry Co., Ltd.), Millionate MR, Millionate MT, Coronate L, Coronate HL, and Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.). These isocyanate compounds may be used alone or in combination of two or more, and a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination. By using a cross-linking agent in combination, it becomes possible to achieve both adhesiveness and repulsion resistance (adhesiveness to curved surfaces), and a PSA sheet with more excellent adhesion reliability can be obtained.

Further, when a difunctional isocyanate compound and a trifunctional or higher isocyanate compound are used in combination as the isocyanate compound, the compounding ratio (mass ratio) of both compounds is [bifunctional isocyanate compound]/[3 Functional or higher isocyanate compound] (mass ratio) is preferably blended at 0.1/99.9 to 50/50, more preferably 0.1/99.9 to 20/80, 0.1/99 0.9 to 10/90 are more preferred, 0.1/99.9 to 5/95 are more preferred, and 0.1/99.9 to 1/99 are most preferred. By adjusting and blending within the above range, a pressure-sensitive adhesive layer having excellent adhesiveness and repulsion resistance is obtained, which is a preferred embodiment.

Examples of the epoxy compound include N,N,N',N'-tetraglycidyl-m-xylenediamine (trade name TETRAD-X, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 1,3-bis(N,N-di glycidylaminomethyl)cyclohexane (trade name TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and the like.

Examples of the melamine-based resin include hexamethylolmelamine. Examples of aziridine derivatives include commercially available products under the trade names HDU, TAZM, and TAZO (manufactured by Sogo Pharmaceutical Co., Ltd.).

Examples of the metal chelate compound include metal components such as aluminum, iron, tin, titanium and nickel, and chelate components such as acetylene, methyl acetoacetate and ethyl lactate.

The content of the cross-linking agent used in the present invention is, for example, preferably 0.01 to 20 parts by mass, and 0.1 to 15 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer. more preferably 0.5 to 10 parts by mass, most preferably 1 to 6 parts by mass. If the content is less than 0.01 parts by mass, the cross-linking formation by the cross-linking agent will be insufficient, and the cohesive force of the obtained pressure-sensitive adhesive layer will be reduced, and sufficient heat resistance may not be obtained. It tends to cause sticky residue. On the other hand, when the content exceeds 20 parts by mass, the cohesive force of the polymer is large, the fluidity is reduced, and the wettability of the adherend (e.g., polarizing plate) becomes insufficient, resulting in the adhesion between the adherend and the pressure-sensitive adhesive. It tends to cause blisters that occur between the layer (pressure-sensitive adhesive composition layer). These cross-linking agents may be used alone, or two or more of them may be mixed and used.

The pressure-sensitive adhesive composition can further contain a cross-linking catalyst for more effectively promoting any of the cross-linking reactions described above. Examples of such cross-linking catalysts include tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris(acetylacetonato)iron (iron(III) acetylacetonate), tris(hexane-2,4-dionato)iron, Tris(heptane-2,4-dionato)iron, Tris(heptane-3,5-dionato)iron, Tris(5-methylhexane-2,4-dionato)iron, Tris(octane-2,4-dionato)iron , tris(6-methylheptane-2,4-dionato)iron, tris(2,6-dimethylheptane-3,5-dionato)iron, tris(nonane-2,4-dionato)iron, tris(nonane-4 ,6-dionato)iron, tris(2,2,6,6-tetramethylheptane-3,5-dionato)iron, tris(tridecan-6,8-dionato)iron, tris(1-phenylbutane-1, 3-Dionato)iron, Tris(hexafluoroacetylacetonato)iron, Tris(ethyl acetoacetate)iron, Tris(acetoacetate-n-propyl)iron, Tris(isopropylacetoacetate)iron, Tris(acetoacetate-n- butyl) iron, tris(sec-butyl acetoacetate) iron, tris(tert-butyl acetoacetate) iron, tris(methyl propionyl acetate) iron, tris(ethyl propionyl acetate) iron, tris(propionyl acetate-n-propyl ) iron, tris(isopropyl propionylacetate) iron, tris(propionylacetate-n-butyl) iron, tris(propionylacetate-sec-butyl) iron, tris(propionylacetate-tert-butyl) iron, tris(benzyl acetoacetate) Iron-based catalysts such as iron, tris(dimethylmalonate)iron, tris(diethylmalonate)iron, trimethoxyiron, triethoxyiron, triisopropoxyiron, and ferric chloride can be used. These crosslinking catalysts may be used alone or in combination of two or more.

The content of the crosslinking catalyst is not particularly limited, but for example, it is preferably about 0.0001 to 1 part by mass, and 0.001 to 0.5 parts by mass, relative to 100 parts by mass of the (meth)acrylic polymer. Parts by mass are more preferred. Within this range, the speed of the cross-linking reaction is high when the pressure-sensitive adhesive layer is formed, and the pot life of the pressure-sensitive adhesive composition is lengthened, which is a preferred embodiment.

Furthermore, the pressure-sensitive adhesive composition can contain a compound that undergoes keto-enol tautomerism. For example, in a pressure-sensitive adhesive composition containing a cross-linking agent or a pressure-sensitive adhesive composition that can be used by blending a cross-linking agent, an aspect containing the compound that causes the keto-enol tautomerism can be preferably employed. As a result, the effect of suppressing excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after blending the cross-linking agent and extending the pot life of the pressure-sensitive adhesive composition can be realized. At least when an isocyanate compound is used as the cross-linking agent, it is particularly significant to include a compound that produces keto-enol tautomerism. This technique can be preferably applied, for example, when the pressure-sensitive adhesive composition is in the form of an organic solvent solution or solvent-free.

Various β-dicarbonyl compounds can be used as the compound that causes keto-enol tautomerism. Specific examples include acetylacetone, 2,4-hexanedione, 3,5-heptanedione, 2-methylhexane-3,5-dione, 6-methylheptane-2,4-dione, 2,6-dimethylheptane- β-diketones such as 3,5-diones; acetoacetic esters such as methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate and tert-butyl acetoacetate; ethyl propionyl acetate, ethyl propionyl acetate, isopropyl propionyl acetate, propionyl acetic acid propionyl acetate esters such as tert-butyl; isobutyryl acetate esters such as ethyl isobutyryl acetate, ethyl isobutyryl acetate, isopropyl isobutyryl acetate, tert-butyl isobutyryl acetate; malonic esters such as methyl malonate and ethyl malonate; mentioned. Among the preferred compounds are acetylacetone and acetoacetates. Compounds that cause such keto-enol tautomerism may be used alone or in combination of two or more.

The content of the compound that causes keto-enol tautomerism can be, for example, 0.1 to 20 parts by mass, usually 0.5 to 15 parts by mass, with respect to 100 parts by mass of the (meth)acrylic polymer. Parts by mass (for example, 1 to 10 parts by mass) are suitable. If the amount of the compound is too small, it may become difficult to exhibit sufficient effects of use. On the other hand, if the compound is used more than necessary, it may remain in the pressure-sensitive adhesive layer and reduce the cohesion.

Furthermore, the pressure-sensitive adhesive composition may contain other known additives such as powders such as lubricants, colorants and pigments, plasticizers, tackifiers, low molecular weight polymers, surface lubricants, agents, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillers, metal powders, particles, foils, etc. It can be added as appropriate depending on the intended use.

<Adhesive Layer and Adhesive Sheet (Surface Protection Film)>
The pressure-sensitive adhesive sheet of the present invention is formed by forming the pressure-sensitive adhesive layer on at least one side of a base film. However, it is also possible to transfer the pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition after cross-linking to a substrate film or the like.

The method of forming the pressure-sensitive adhesive layer on the base film is not particularly limited. It is produced by forming on a substrate film. After that, curing may be carried out for the purpose of adjusting component migration of the pressure-sensitive adhesive layer and adjusting the cross-linking reaction. Further, when the pressure-sensitive adhesive composition is coated on a base film to prepare a pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition contains one or more solvents other than a polymerization solvent so that the pressure-sensitive adhesive composition can be uniformly coated on the base film. may be newly added.

Moreover, as a method for forming the adhesive layer when producing the adhesive sheet of the present invention, a known method used for producing adhesive tapes is used. Specific examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, and extrusion coating using a die coater.

The pressure-sensitive adhesive sheet of the present invention is usually produced so that the thickness of the pressure-sensitive adhesive layer is about 3 to 100 μm, preferably about 5 to 50 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, it is easy to obtain an appropriate balance between removability and adhesiveness, which is preferable.

The adhesive sheet of the present invention preferably has a total thickness of 8 to 300 μm, more preferably 10 to 200 μm, most preferably 20 to 100 μm. Within the above range, adhesive properties (removability, adhesiveness, etc.), workability, and appearance properties are excellent, which is a preferred embodiment. In addition, the said total thickness means the total thickness including all layers, such as a base film, an adhesive layer, and another layer.

<Separator>
In the pressure-sensitive adhesive sheet of the present invention, it is preferable that a separator is attached to the surface of the pressure-sensitive adhesive layer opposite to the surface in contact with the base film. The separator can be attached to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface, if necessary.

Materials for the separator include paper and plastic films, and plastic films are preferably used because of their excellent surface smoothness. The film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. Examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer Coalesced films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films and the like.

The thickness of the separator is usually 5 to 200 μm, preferably about 10 to 100 μm. When it is within the above range, it is preferable because it is excellent in lamination workability to the pressure-sensitive adhesive layer and peeling workability from the pressure-sensitive adhesive layer. If necessary, the separator may be subjected to release and antifouling treatment using a silicone, fluorine, long-chain alkyl or fatty acid amide release agent, silica powder, etc.; It is also possible to perform antistatic treatment such as

In the pressure-sensitive adhesive sheet of the present invention, it is preferable that the fluorine-based oligomer is present (applied/laminated) on the surface of the separator that is in contact with the pressure-sensitive adhesive layer (see FIG. 1). Since the fluorine-based oligomer is present on the surface of the separator that is in contact with the pressure-sensitive adhesive layer, when the separator is attached to the pressure-sensitive adhesive layer, the fluorine-based oligomer is removed from the pressure-sensitive adhesive layer from the separator surface. It is transferred (migrated) to the surface, and after bonding the adhesive layer to an adherend (e.g., polarizing plate), it has an easy peeling effect due to the low surface free energy of the fluorine site, and also functions as a tackifying resin, Adhesiveness can be improved, and slippage (displacement), floating, and peeling of the surface protective film can be suppressed (both removability and adhesiveness are compatible), which is a more preferable embodiment.

<Optical member>
The optical member of the present invention is preferably adhered (protected) by the pressure-sensitive adhesive sheet or, when the separator is adhered, by the pressure-sensitive adhesive sheet from which the separator is removed. Since the pressure-sensitive adhesive sheet is excellent in curl adjustment and easy peelability, it can be used for surface protection (surface protection film) during processing, transportation, shipping, etc., and thus protects the surface of the optical member (polarizing plate, etc.). Therefore, it becomes useful.

Several examples related to the present invention are described below, but the present invention is not intended to be limited to those shown in such specific examples. "Parts" and "%" in the following description are based on mass unless otherwise specified. In addition, the blending amount (addition amount) in the table is shown.

Each characteristic in the following description was measured or evaluated as follows.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) of the polymer used was measured using a GPC apparatus (HLC-8220GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.
Sample concentration: 0.2% by mass (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6ml/min
Measurement temperature: 40°C
column:
Sample column; TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1 column)
Detector: differential refractometer (RI)
In addition, the weight average molecular weight was calculated|required by the polystyrene conversion value. Also, when measuring the number average molecular weight (Mn), it was measured in the same manner as the weight average molecular weight (Mw).

<Bubbling of adhesive composition (solution)>
After mixing and stirring the pressure-sensitive adhesive composition (solution) according to each example, foaming of the pressure-sensitive adhesive composition (solution) was visually observed. The evaluation was made as ◯ when no foaming was observed, Δ when slight foaming was observed, and x when clear foaming was observed.

<Shear force>
After cutting the surface protective film into a size of 10 mm in width and 100 ^mm in length, and peeling off the separator, a TAC polarizing plate (manufactured by Nitto Denko Co., Ltd., SEG1423DU polarizing plate, width: 25 mm, length: 100 mm), pulled in the shear direction at a pulling rate of 0.06 mm/min at 23°C, and the maximum load (N/cm ² ) at that time was taken as the shear force.

In the surface protective film of the present invention, the pressure-sensitive adhesive layer used in the surface protective film preferably has a shear force of 5 N/cm ² or more at 23° C.×50% RH against the polarizing plate, and preferably 5 to 50 N/cm. ² , more preferably 7 to 40 N/cm ² . By adjusting the shearing force to 5 N/cm ² or more, it is possible to suppress slippage (displacement), lifting, peeling, and the like after application to the adherend, and excellent curl controllability, which is a preferred embodiment.

<Measurement of peeling electrification voltage>
The adhesive sheet 1 according to each example was cut into a size of 70 mm in width and 130 mm in length, and after peeling off the release liner (separator), a polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width : 70 mm, length: 100 mm) 20, one end of the pressure-sensitive adhesive sheet 1 protruded from the end of the polarizing plate 20 by 30 mm, and was press-bonded with a hand roller.
After leaving this sample in an environment of 23° C. and 50% RH for one day, it was set at a predetermined position on a sample fixing table 30 having a height of 20 mm, as shown in FIG. The end of the pressure-sensitive adhesive sheet (surface protection film) 1 protruding from the polarizing plate 20 by 30 mm was fixed to an automatic winder (not shown), and the adhesive sheet was peeled off at a peeling angle of 150° and a peeling speed of 30 m/min. The potential on the surface of the adherend (polarizing plate 20) generated at this time is measured by a potential measuring device 40 (manufactured by Shishido Electrostatic Co., Ltd., model "STATIRON DZ-4") fixed at a position 30 mm in height from the center of the polarizing plate 20. ”), the “peeling electrification voltage” was measured. The measurement was performed under the environment of 23° C. and 50% RH.

The peeling electrostatic voltage (kV) (absolute value) in the present invention is preferably 1.0 or less, more preferably 0.5 or less, and still more preferably 0.3 or less. When it is within the above range, it is excellent in antistatic properties and peeling electrification properties, and is also excellent in workability, which is a preferable embodiment.

<Presence or absence of contamination (contamination resistance)>
The pressure-sensitive adhesive sheet according to each example was cut into a size of 50 mm in width and 80 mm in length, and the separator was peeled off. A hand roller was used to crimp the sample while inserting it, and an evaluation sample was produced. After the evaluation sample was left in an environment of 70° C. for 120 hours, the pressure-sensitive adhesive sheet was peeled off from the adherend by hand, and traces of air bubbles on the adherend surface at that time were visually observed. In the evaluation, ◯ was given when no trace of air bubbles was observed, and x was given when traces of air bubbles were observed.

<Measurement of low-speed peel force>
After leaving for 24 hours in an environment of 23 ° C. × 50% RH, the surface protective film cut into a width of 25 mm and a length of 100 mm was applied to a TAC polarizing plate (manufactured by Nitto Denko, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) at a pressure of 0.25 MPa and a speed of 0.3 m/min to prepare an evaluation sample. After the lamination, after being left in an environment of 23 ° C. × 50% RH for 30 minutes, the low speed peel force when peeled at a peel speed of 0.3 m / min (low speed peel) and a peel angle of 180 ° with a universal tensile tester (N/25 mm) was measured. The measurement was performed under an environment of 23°C and 50% RH.

In the surface protective film of the present invention, the pressure-sensitive adhesive layer used in the surface protective film has a 180° peel adhesive force (tensile speed 0.3 m / min: low-speed peel force) at 23 ° C. × 50% RH to a polarizing plate, It is preferably 0.15 N/25 mm or less, more preferably 0.01 to 0.15 N/25 mm, even more preferably 0.02 to 0.14 N/25 mm. By adjusting the peel adhesive strength (tensile speed of 0.3 m / min) to 0.15 N / 25 mm or less, when the surface protective film becomes unnecessary, the peeling work becomes easy (removability), and the adhesion It is possible to prevent damage to the body, etc., which is a preferable aspect.

<Preparation of acrylic polymer (1)>
A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser was charged with 96 parts by mass of 2-ethylhexyl acrylate (2EHA), 4 parts by mass of 2-hydroxyethyl acrylate (HEA), and 2 parts by mass as a polymerization initiator. , 2′-azobisisobutyronitrile 0.2 parts by mass and ethyl acetate 150 parts by mass were charged, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65° C. for 6 hours of polymerization. A reaction was carried out to prepare an acrylic polymer (1) solution (40% by mass). The acrylic polymer (1) had a weight average molecular weight (Mw) of 540,000.

<Preparation of acrylic polymer (2)>
91 parts by mass of 2-ethylhexyl acrylate (2EHA), 9 parts by mass of 4-hydroxybutyl acrylate (4HBA), and acrylic acid (AA) were placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. 0.02 parts by mass, 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 150 parts by mass of ethyl acetate were charged, and nitrogen gas was introduced while gently stirring, and the liquid in the flask was A polymerization reaction was carried out for 6 hours while keeping the temperature around 65° C. to prepare an acrylic polymer (2) solution (40% by mass). The acrylic polymer (2) had a weight average molecular weight (Mw) of 540,000.

<Preparation of acrylic polymer (3)>
98.5 parts by mass of 2-ethylhexyl acrylate (2EHA), 1.5 parts by mass of 4-hydroxybutyl acrylate (4HBA), and polymerization 0.2 parts by mass of 2,2'-azobisisobutyronitrile and 150 parts by mass of ethyl acetate were charged as initiators, nitrogen gas was introduced while gently stirring, and the liquid temperature in the flask was maintained at around 65°C. A polymerization reaction was carried out for 6 hours to prepare an acrylic polymer (3) solution (40% by mass). The acrylic polymer (3) had a weight average molecular weight (Mw) of 550,000.

<Example 1>
[Preparation of acrylic adhesive solution]
The acrylic polymer (1) solution (40% by mass) was diluted with ethyl acetate to 20% by mass, and 500 parts by mass of this solution (solid content: 100 parts by mass) was added with a fluorine-based oligomer (Megafac F-562, DIC Corporation). ) diluted to 10% with ethyl acetate (0.05 parts by mass of solids), and 5 parts by mass of a solution of LiTFSI as an ionic compound diluted to 10% with ethyl acetate (0.05 parts by mass of solids). 5 parts by mass), 3 parts by mass of isocyanurate (Coronate HX, manufactured by Tosoh Corporation) of hexamethylene diisocyanate, which is a trifunctional isocyanate compound, as a cross-linking agent (solid content: 3 parts by mass), and dibutyltin dilaurate as a cross-linking catalyst (1 mass % ethyl acetate solution) was added, and mixed and stirred to prepare an acrylic pressure-sensitive adhesive solution.

[Preparation of antistatic treatment film]
Antistatic agent (manufactured by Solvex Co., Ltd., Microsolver RMd-142, containing tin oxide and polyester resin as main components) 10 parts by weight is diluted with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol to prevent static electricity. A drug solution was prepared.
The resulting antistatic agent solution was applied onto a polyethylene terephthalate (PET) film (thickness: 38 μm) using a Meyer bar and dried at 130° C. for 1 minute to remove the solvent and form an antistatic layer (thickness: 38 μm). thickness: 0.2 μm) to prepare an antistatic film.

[Preparation of adhesive sheet (surface protective film)]
The acrylic pressure-sensitive adhesive solution was applied to the opposite side of the antistatic-treated film, and heated at 130° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 15 μm. Next, a silicone-treated surface of a polyethylene terephthalate film (thickness: 25 μm) having one side silicone-treated was attached to the surface of the adhesive layer to prepare an adhesive sheet.

<Examples 2 to 12>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 using the raw materials and blending amounts shown in Table 1.

<Example 13>
[Preparation of urethane adhesive solution]
As polyols, Preminol S3011 (manufactured by Asahi Glass Co., Ltd., Mn = 10000) 85 parts by mass, which is a polyol having three hydroxyl groups, Sannics GP3000 (manufactured by Sanyo Kasei Co., Ltd., Mn = 3000) which is a polyol having three hydroxyl groups 13 Part by mass, 2 parts by mass of Sannics GP1000 (manufactured by Sanyo Kasei Co., Ltd., Mn = 1000), which is a polyol having three hydroxyl groups, and 18 parts by mass of an isocyanate compound (Coronate HX: C/HX, manufactured by Nippon Polyurethane Co., Ltd.) as a cross-linking agent. , As a catalyst, iron (III) acetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.04 parts by weight, fluorine-based oligomer Megafac F-562 (manufactured by DIC) 0.2 parts by weight, 1- as an ionic compound 1 part by mass of ethyl-3-methylimidazolium tri(fluoromethanesulfonyl)imide (EMITFSI, manufactured by Tokyo Kasei Kogyo Co., Ltd.) and 210 parts by mass of ethyl acetate as a dilution solvent were blended to obtain a urethane adhesive solution. Then, in the same manner as in Example 1, a pressure-sensitive adhesive sheet was prepared by adjusting the heating conditions and the thickness of the resulting pressure-sensitive adhesive layer.

<Example 14>
[Preparation of silicone adhesive solution]
As a silicone adhesive, "X-40-3229" (solid content 60% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.) is used as a solid content of 100 parts by mass, and as a platinum catalyst, "CAT-PL-50T" (Shin-Etsu Chemical Co., Ltd. ) 0.5 parts by mass, fluorine-based oligomer Megafac F-562 (manufactured by DIC) 0.2 parts by mass, 1-ethyl-3-methylimidazolium tri(fluoromethanesulfonyl) imide (EMITFSI) as an ionic compound , manufactured by Tokyo Chemical Industry Co., Ltd.) and 100 parts by mass of toluene as a solvent were blended to obtain a silicone adhesive solution. Then, in the same manner as in Example 1, a pressure-sensitive adhesive sheet was prepared by adjusting the heating conditions and the thickness of the resulting pressure-sensitive adhesive layer.

<Comparative Examples 1 to 3>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 using the raw materials and blending amounts shown in Table 1.

Tables 1 and 2 show the results of the above-described formulations, various measurements, and evaluations of the pressure-sensitive adhesive sheets according to Examples and Comparative Examples. In addition, the compounding quantity in Table 1 shows an active ingredient. Also, the abbreviations in Table 1 are explained below.

[Fluorine-based oligomer]
F-562: fluorine-based oligomer, weight average molecular weight 27900, manufactured by DIC, trade name: Megafac F-562
F-558: fluorine-based oligomer, weight average molecular weight 11900, manufactured by DIC, trade name: Megafac F-558
F-569: fluorine-based oligomer, weight average molecular weight 6920, manufactured by DIC, trade name: Megafac F-569
222F: fluorine-based oligomer, weight average molecular weight 2940, manufactured by Neos, trade name: Futergent 222F

[Oxyalkylene group-containing compound]
PD-420: Oxyalkylene group-containing compound containing no organopolysiloxane (HLB value: 12.6), manufactured by Kao Corporation, trade name: Latemul PD-420
KF-353: Oxyalkylene chain-containing organopolysiloxane, manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-353

[Ionic compounds]
LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide, manufactured by Tokyo Chemical Industry Co., Ltd. Bu ₃ MePTFSI: Tributylmethylphosphonium bis(trifluoromethanesulfonyl)imide, manufactured by Tokyo Chemical Industry Co., Ltd. X-40-2450: Ionic group-containing silicone, Shin-Etsu Chemical company BMPTFSI: 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide, Wako Pure Chemical Industries MTOATFSI: methyltrioctylammonium bis (trifluoromethanesulfonyl) imide, Tokyo Chemical Industry Co., Ltd. EMITFSI: 1- Ethyl-3-methylimidazolium tri(fluoromethanesulfonyl)imide, manufactured by Tokyo Chemical Industry Co., Ltd.

From Table 2, it was confirmed that all the examples were excellent in shear force and peeling electrification voltage. In addition, when the amount of the fluorine-based oligomer is adjusted to 5.5 parts by mass or less, which is excellent in stain resistance, with respect to 100 parts by mass of the polymer used, stain resistance (low staining) is also obtained. It was confirmed to be excellent. Furthermore, it was confirmed that foaming of the pressure-sensitive adhesive composition (solution) could be suppressed in the examples using the fluorine-based oligomer having a weight-average molecular weight of 20,000 or more.

On the other hand, from Table 2, it was confirmed that Comparative Example 1 was inferior in peeling electrification voltage because no ionic compound was blended, and Comparative Example 2 was inferior in shear force because no fluorine-based oligomer was blended. In addition, in Comparative Example 3, since the fluorine-based oligomer having a weight average molecular weight of less than 3500 was used, it was confirmed that the shear force was inferior. In addition, in Comparative Example 3, since the fluorine-based oligomer 222F having a weight-average molecular weight of less than 20000 was used, foaming of the pressure-sensitive adhesive composition (solution) was confirmed.

The pressure-sensitive adhesive sheet disclosed herein protects optical members used as constituent elements of liquid crystal display panels, plasma display panels (PDP), organic electroluminescence (EL) displays, etc. during production, transport, and the like. It is suitable as a surface protective film for In particular, surface protective films (optical surface It is useful as a protective film).

1: Adhesive sheet 10: Glass plate 11: Separator 12: Fluorine-based oligomer coating film 13: Adhesive layer 14: Base film 20: Polarizing plate 30: Sample fixing base 40: Potential measuring device

Claims (5)

on at least one side of the base film,
Containing an adhesive polymer, a fluorine-based oligomer having a weight average molecular weight of 20000 or more, and an ionic compound,
The adhesive polymer is at least one selected from the group consisting of (meth)acrylic polymers, urethane polymers, and silicone polymers, and has an adhesive layer formed from an adhesive composition,
The fluorine-based oligomer is present inside and/or on the surface of the pressure-sensitive adhesive layer,
A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer has a shearing force of 5 N/cm ² or more at 23° C.×50% RH with respect to the polarizing plate. The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive composition contains an oxyalkylene group-containing compound. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein a separator is attached to the surface of the pressure-sensitive adhesive layer opposite to the surface in contact with the base film. 4. The pressure-sensitive adhesive sheet according to claim 3, wherein the fluorine-based oligomer is present on the surface of the separator that contacts the pressure-sensitive adhesive layer. 5. An optical member, wherein a pressure-sensitive adhesive sheet obtained by separating the separator from the pressure-sensitive adhesive sheet according to claim 3 or 4 is adhered.

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