JP6670389B2 - Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, and optical member - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and an optical member. In particular, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition is used for sticking to a plastic product or the like in which static electricity is easily generated (for example, a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, and the like). It is particularly suitable for protecting the surface of an optical member (for example, a polarizing plate, a wavelength plate, a retardation plate, an optical compensation film, a reflection sheet, and a brightness enhancement film used for a liquid crystal display or the like). It is useful as a surface protective film.

  A surface protection film (also referred to as a surface protection sheet) generally has a configuration in which an adhesive layer is provided on a film-like base film (support). Such a protective film is adhered to an adherend (protected object) via the above-mentioned pressure-sensitive adhesive layer, and is used for the purpose of protecting the adherend from scratches and dirt during processing, transportation, and the like. For example, a panel of a liquid crystal display is formed by attaching an optical member such as a polarizing plate or a wavelength plate to a liquid crystal cell via an adhesive layer. In manufacturing 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 rubbed and damaged by a transport roll or the like in an intermediate step, a measure is taken to attach a surface protective film to one side or both sides (typically, one side) of the polarizing plate. The surface protection film is peeled and removed when it becomes unnecessary.

  Generally, since the surface protection film and the optical member are made of a plastic material, they have high electrical insulation properties and generate static electricity due to friction or peeling. For this reason, static electricity is easily generated even when the surface protective film is peeled off from an optical member such as a polarizing plate, and when a voltage is applied to the liquid crystal while the static electricity remains, the alignment of the liquid crystal molecules is lost, There is also a concern that the panel may be damaged. In addition, the presence of static electricity can be a factor of sucking dust and lowering workability. Under such circumstances, an antistatic treatment is performed on the surface protective film. For example, forming an antistatic layer or applying an antistatic coating as a surface layer (top coat layer, back layer) of the surface protective film. (See Patent Documents 1 and 2).

  Further, in order to impart an antistatic property to the pressure-sensitive adhesive layer itself constituting the surface protective film, an ionic compound such as an alkali metal salt or an ionic liquid that functions as an antistatic agent is contained in the pressure-sensitive adhesive. (See Patent Document 3).

  However, when the surface of the pressure-sensitive adhesive layer containing the ionic compound is stored in a high-temperature (warmed) environment with the surface of the pressure-sensitive adhesive layer attached to an optical member such as a polarizing plate, the ionic compound permeates from the surface of the optical member. In addition, there is a problem that the antistatic ability of the ionic compound is reduced and the optical member cannot be sufficiently protected.

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

  Accordingly, the present invention has been made in view of the above circumstances, and as a result of intensive research, it has been found that even when the optical member such as a polarizing plate is stuck and stored under a high-temperature environment, the antistatic property and the peeling voltage can be stabilized over time. It is an object of the present invention to provide a pressure-sensitive adhesive composition capable of achieving a property, 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.

（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。）That is, the pressure-sensitive adhesive composition of the present invention is characterized by containing a pressure-sensitive adhesive polymer and an ionic group-containing silicone represented by the following formula (1).

(R _{1 to} R ₄ may be the same or different and include any of an alkyl group having 1 to 10 carbon atoms, an alkoxy group, an aryl group, an alicyclic group, a fluorine-substituted alkyl group, and an ionic group; One or more of R _{1 to} R ₄ contains an ionic group. N is an integer of 0 to 100.)

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

  The pressure-sensitive adhesive composition of the present invention preferably contains at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive.

  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 surface of a substrate film, and contains the ionic group-containing inside and / or surface of the pressure-sensitive adhesive layer. Preferably, silicone is present.

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

  In the pressure-sensitive adhesive sheet of the present invention, it is preferable that the ionic group-containing silicone is present on a 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 a pressure-sensitive adhesive sheet obtained by peeling the separator from the pressure-sensitive adhesive sheet.

  The present invention, by using a pressure-sensitive adhesive composition containing a specific ionic group-containing silicone, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition for an optical member such as a polarizing plate, It is useful because it can achieve excellent antistatic properties and stability over time of peeling electrostatic voltage even when it is stuck and stored in a high-temperature environment.

It is a typical sectional view showing an example of 1 composition of an adhesive sheet (surface protection film) concerning the present invention. It is explanatory drawing which shows the measuring method of a peeling charge voltage.

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

<Overall structure of adhesive sheet (surface protection film)>
The pressure-sensitive adhesive sheet disclosed herein is generally in a form called a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive film, or the like, and is particularly used as an optical component (for example, a liquid crystal display panel component such as a polarizing plate or a wave plate). It is suitable as a surface protection film for protecting the surface of the optical component during processing or transporting the optical component. The pressure-sensitive adhesive layer in the surface protective film is typically formed continuously, but is not limited to such a form.For example, the pressure-sensitive adhesive layer is formed in a regular or random pattern such as a dot shape and a stripe shape. It may be an adhesive layer. Further, the surface protective film disclosed herein may be in a roll shape or a single-leaf shape.

<Base film>
The pressure-sensitive adhesive sheet (surface protective film) of the present invention is characterized by having a base film. In the technology disclosed herein, the resin material constituting the base film can be used without any particular limitation. For example, transparency, mechanical strength, heat stability, moisture shielding property, isotropic property, It is preferable to use one 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 by a roll coater or the like and can be wound into a roll, which is useful.

  Examples of the base film (substrate, support) include, for example, polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate A plastic film composed of a resin material containing a main polymer component (a main component of the resin component, typically a component occupying 50% by mass or more) of a base polymer; an 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 copolymer; olefin-based polymers such as polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, and ethylene-propylene copolymer; Examples of the resin material include vinyl chloride polymers; amide polymers such as nylon 6, nylon 6,6, and aromatic polyamide; and the like. Still other examples of the resin material include an imide polymer, a sulfone polymer, a polyether sulfone polymer, a polyether ether ketone polymer, a polyphenylene sulfide polymer, a vinyl alcohol polymer, a vinylidene chloride polymer, and a vinyl butyral polymer. Allylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and the like. A base film composed of a blend of two or more of the above-mentioned polymers may be used.

  As the base film, a plastic film made of a transparent thermoplastic resin material can be preferably used. It is a more preferable embodiment to use a polyester film among the plastic films. Here, the polyester film is a film having a polymer material (polyester resin) having a main skeleton based on an ester bond such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polybutylene terephthalate as a main resin component. Say. Such a polyester film has preferable characteristics as a base film of a surface protective film, such as excellent optical characteristics and dimensional stability, but has a property of being easily charged as it is.

  Various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a coloring agent (eg, a pigment or a dye) may be added to the resin material constituting the base film, if necessary. For example, a known or commonly used surface treatment such as a corona discharge treatment, a plasma treatment, an ultraviolet irradiation treatment, an acid treatment, an alkali treatment, and the application of a primer may be applied. Such a surface treatment may be, for example, a treatment for increasing 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, it is possible to use a plastic film that has been subjected to an antistatic treatment as the base film. The use of the base film is preferable because the charging of the pressure-sensitive adhesive sheet itself when peeled is suppressed. In addition, the base film is a plastic film, and by subjecting the plastic film to an antistatic treatment, it is possible to obtain an adhesive sheet in which the charge of the pressure-sensitive adhesive sheet itself is reduced and the antistatic property to the adherend is excellent. The method of imparting the antistatic function is not particularly limited, and a conventionally known method can be used. For example, an antistatic resin or a conductive polymer including an antistatic agent and a resin component, a conductive polymer, or a conductive substance may be used. Examples thereof include a method of applying a conductive resin to be contained, 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 about 5 to 200 μm, preferably about 10 to 100 μm. It is preferable that the thickness of the base film is within the above range, since the workability of laminating to the adherend and the workability of peeling from the adherend are excellent.

  The pressure-sensitive adhesive sheet disclosed herein may be embodied in a mode that further includes another layer in addition to the base film and the pressure-sensitive adhesive layer. Examples of the other layer include an undercoat layer (anchor layer) for improving the anchoring property of the antistatic layer and the pressure-sensitive adhesive layer.

<Adhesive composition>
The pressure-sensitive adhesive sheet of the present invention has the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition, and as the pressure-sensitive adhesive composition, if it has pressure-sensitive adhesiveness, Can be used without restrictions. As the pressure-sensitive adhesive composition, for example, an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a synthetic rubber-based pressure-sensitive adhesive, a natural rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and the like, among which more preferably, Acrylic adhesive using a (meth) acrylic polymer which is at least one selected from the group consisting of an acrylic adhesive, a urethane-based adhesive, and a silicone-based adhesive, and particularly preferably is an adhesive polymer. The use of an agent.

  When the pressure-sensitive adhesive layer uses an acrylic pressure-sensitive adhesive, the (meth) acryl-based polymer, which is a pressure-sensitive adhesive polymer that forms the acrylic pressure-sensitive adhesive, has a C 1-14 alkyl as a raw material monomer that forms the same. A (meth) acrylic monomer having a group can be used as the main monomer. As the (meth) acrylic monomer, one or more kinds can be used. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the peeling force (adhesive force) to an adherend (protected body) can be easily controlled to be low, and light peeling can be achieved. A pressure-sensitive adhesive sheet (surface protective film) having excellent properties and removability is obtained. In the present invention, the (meth) acrylic polymer refers to an acrylic polymer and / or a methacrylic polymer, and the (meth) acrylate refers to an acrylate and / or a methacrylate.

  Specific examples of the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth). ) Acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl ( (Meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, and the like. Can be

  Among them, in the case of a surface protective film as the pressure-sensitive adhesive sheet of the present invention, 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, n- (Meth) acrylic monomers having an alkyl group having 4 to 14 carbon atoms, such as tetradecyl (meth) acrylate, are preferred. In particular, by using a (meth) acrylic monomer having an alkyl group having 4 to 14 carbon atoms, it is 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 that the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms has a (meth) acrylic monomer content of 50% by mass or more based on 100% by mass of the total amount of the 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 the amount is less than 50% by mass, the wettability of the pressure-sensitive adhesive composition and the cohesive strength of the pressure-sensitive adhesive layer become poor, which is not preferable.

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer preferably contains a hydroxyl group-containing (meth) acrylic monomer as a raw material monomer. As the hydroxyl group-containing (meth) acrylic monomer, one kind or two or more kinds can be used. By using the hydroxyl group-containing (meth) acrylic monomer, it becomes easy to control the crosslinking of the pressure-sensitive adhesive composition, and the balance between the improvement of the wettability by the flow and the reduction of the peeling force (adhesive force) in the peeling is further improved. It becomes easier to control. Furthermore, unlike a carboxyl group or a sulfonate group which can generally act as a crosslinking site, a hydroxyl group has an appropriate interaction with an ionic group-containing silicone or an oxyalkylene group-containing compound which is an antistatic component (antistatic agent). Therefore, it can be suitably used also in terms of antistatic properties.

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

  The hydroxyl group-containing (meth) acrylic monomer preferably contains 25% by mass or less, more preferably 20% by mass or less, based on 100% by mass of the total amount of the monomer components constituting the (meth) acrylic polymer. , More preferably 0.1 to 15% by mass, and most preferably 1 to 10% by mass. It is preferable for it to be in the above-mentioned range because the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force of the obtained pressure-sensitive adhesive layer can be easily controlled.

  Further, as another polymerizable monomer component, the Tg is set to 0 ° C. or lower (usually −100 ° C. or higher) so that the glass transition temperature and the peeling of the (meth) acrylic polymer can be improved because the adhesive performance can be easily balanced. A polymerizable monomer or the like for adjusting the properties can be used as long as the effects of the present invention are not impaired.

  As the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms used in the (meth) acrylic polymer, and other polymerizable monomers other than the hydroxyl group-containing (meth) acrylic monomer, A carboxyl group-containing (meth) acrylic monomer can be used. By using the carboxyl group-containing (meth) acrylic monomer, it is possible to suppress an increase in the adhesive force of the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) over time, and to prevent re-peeling, increase the adhesive force, and workability. It is preferable because it is excellent in shear strength together with cohesive strength of the pressure-sensitive adhesive layer.

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

  The carboxyl group-containing (meth) acrylic monomer is preferably from 0 to 5% by mass, and more preferably from 0 to 3% by mass, based on 100% by mass of the total amount of the monomer components constituting the (meth) acrylic polymer. Is more preferably 0 to 2% by mass, and most preferably 0 to 0.19% by mass. When the content exceeds 5% by mass, a large number of acid functional groups such as a carboxyl group having a large polar action are present, and when an ionic group-containing silicone or an oxyalkylene group-containing compound as an antistatic component is blended, the antistatic component is used. For example, when an acid functional group such as a carboxyl group interacts, ion conduction is hindered, conductivity efficiency is reduced, and sufficient antistatic properties may not be obtained, which is not preferable.

  Further, when the hydroxyl group-containing (meth) acrylic monomer and the carboxyl group-containing (meth) acrylic monomer are used in combination, the total amount of the monomer components constituting the (meth) acrylic polymer is 100% by mass. And the carboxyl group-containing (meth) acrylic monomer is preferably contained in an amount of 0.01 to 0.19% by mass. By adjusting the content within the above range, a pressure-sensitive adhesive composition having excellent removability and prevention of an increase in adhesive strength can be obtained while maintaining the antistatic property, which is effective.

  Further, 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 used in the (meth) acrylic polymer. Any other polymerizable monomer other than the monomer can be used without any particular limitation as long as the properties of the present invention are not impaired. For example, components for improving cohesion and heat resistance, 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-acryloyl morpholine In addition, a component having a functional group that functions as a base for improving a peeling force (adhesive strength) or a crosslinking point, such as a vinyl ether monomer, can be used as appropriate. Among them, it is preferable to use a nitrogen-containing monomer such as a cyano group-containing monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and N-acryloylmorpholine. Use of a nitrogen-containing monomer is useful because it can ensure an appropriate peeling force (adhesive force) that does not cause lifting or peeling, and can provide an adhesive sheet (surface protective film) with excellent shearing force. . One 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 Examples include 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, methyl glycidyl (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, a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, a hydroxyl group-containing (meth) acrylic monomer, and a carboxyl group-containing (meth) acrylic monomer other than the polymerizable monomer, The amount 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 to obtain desired properties.

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

  The average addition mole number of the oxyalkylene unit of the alkylene oxide group-containing reactive monomer is from 1 to 40 from the viewpoint of compatibility with an ionic group-containing silicone or an oxyalkylene group-containing compound as an antistatic component. Is preferably 3 to 40, more preferably 4 to 35, and particularly preferably 5 to 30. When the average number of moles is 1 or more, the effect of reducing contamination of the adherend (protected body) tends to be efficiently obtained. When the average number of moles is larger than 40, the interaction with the ionic group-containing silicone or the oxyalkylene group-containing compound is large, and the viscosity of the pressure-sensitive adhesive composition tends to increase, so that the coating tends to be difficult. It is not preferable because there is. In addition, the terminal of the oxyalkylene chain may be substituted with a hydroxyl group or another functional group.

  The alkylene oxide group-containing reactive monomer may be used alone, or two or more kinds may be used as a mixture. However, the total content is based on the total amount of the monomer components of the (meth) acrylic polymer. Of these, the content is preferably 0 to 20% by mass, and more preferably 0 to 10% by mass. When the content of the alkylene oxide group-containing reactive monomer exceeds 20% by mass, the interaction with the ionic group-containing silicone or the oxyalkylene group-containing compound becomes large, ionic conduction is hindered, and the antistatic property is reduced. Is not preferred.

  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 an oxymethylene group, an oxyethylene group, an oxypropylene group, and an oxybutylene group. Can be 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 reactive monomer-containing (meth) acrylic polymer having an ethylene oxide group as the base polymer, the compatibility between the base polymer and the ionic group-containing silicone or oxyalkylene group-containing compound is improved, and Bleed is suitably suppressed, and a low-staining adhesive composition is obtained.

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

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

  Specific examples of the reactive surfactant include an anionic reactive surfactant having a (meth) acryloyl group or an allyl group, a nonionic reactive surfactant, and a cationic reactive surfactant. Is raised.

  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, further preferably 300,000 to 3,000,000, and most preferably 300,000 to 950,000. It is. When the weight average molecular weight is smaller than 100,000, adhesive force tends to remain due to a decrease in the cohesive force of the pressure-sensitive adhesive layer. On the other hand, when the weight-average molecular weight exceeds 5,000,000, the fluidity of the polymer decreases, the wetting on the adherend (eg, polarizing plate) becomes insufficient, and the adherend and the pressure-sensitive adhesive sheet (surface protective film) It tends to cause blisters generated between the pressure-sensitive adhesive layers. The weight average molecular weight refers to a value obtained by measurement by GPC (gel permeation chromatography).

  Further, 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 less likely to flow, for example, the wetting of the polarizing plate as an optical member becomes insufficient, and the gap between the polarizing plate and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (surface protective film) is increased. It tends to cause blistering. In particular, when the glass transition temperature is -61 ° C or lower, a pressure-sensitive adhesive layer excellent in wettability to a polarizing plate and light peelability is easily obtained. 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 used.

  The method of polymerizing the (meth) acrylic polymer is not particularly limited, and can be polymerized by a known method such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization. Solution polymerization is a more preferred embodiment from the viewpoint of characteristics such as low contamination of the adherend (protected body). Further, the obtained polymer may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer and the like.

  When a urethane-based pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer, any appropriate urethane-based pressure-sensitive adhesive can be adopted. As such a urethane-based pressure-sensitive adhesive, preferably, a pressure-sensitive adhesive obtained by reacting a polyol with a polyisocyanate compound is used. Examples of the polyol include a polyether polyol, a polyester polyol, a polycarbonate polyol, and a polycaprolactone polyol. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, and hexamethylene diisocyanate.

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

  Examples of the silicone-based pressure-sensitive adhesive include an addition reaction-curable silicone-based pressure-sensitive adhesive and a peroxide-curable silicone-based pressure-sensitive adhesive. Among these silicone-based pressure-sensitive adhesives, addition reaction-curable silicone-based pressure-sensitive adhesives are preferable because a peroxide (such as benzoyl peroxide) is not used and a decomposition product is not generated.

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

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。<Ionic group-containing silicone>
The pressure-sensitive adhesive composition of the present invention is characterized by containing a pressure-sensitive adhesive polymer and an ionic group-containing silicone represented by the following formula (1). By including the ionic group-containing silicone in the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer is stuck to the surface of an adherend (for example, a polarizing plate) by a low surface free energy of a silicone chain under a high temperature environment. Even when stored, the ionic group-containing silicone does not penetrate into the adherend (from the surface of the adherend to the inside of the adherend) and tends to remain on the surface of the pressure-sensitive adhesive layer. This is a preferable embodiment in which the charging characteristics are stable and the antistatic performance is maintained for a long period of time. The `` inside '' of the pressure-sensitive adhesive layer is, for example, when the pressure-sensitive adhesive layer is formed using the pressure-sensitive adhesive composition containing the ionic group-containing silicone, when the pressure-sensitive adhesive layer is included in the pressure-sensitive adhesive layer. Point to. Further, the “surface” of the pressure-sensitive adhesive layer refers to, for example, when the pressure-sensitive adhesive layer is formed by using the pressure-sensitive adhesive composition containing the ionic group-containing silicone or not mixed, In order to protect the surface of the agent layer, the ionic group-containing silicone is applied (laminated) in advance on the surface of the separator to be attached, and when the separator is attached to the pressure-sensitive adhesive layer, It refers to the case where the ionic group-containing silicone is transferred (transferred) to the surface of the pressure-sensitive adhesive layer.

Note that R _{1 to} R ₄ in the above formula (1) may be the same or different, and have 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 at least _one of R _{1 to} R ₄ contains an ionic group. n is an integer of 0 to 100.

The ionic group contained in one or more of R _{1 to} R ₄ is preferably an ionic group having an ammonium cation group or a phosphonium cation group. Among them, at least one of R _{1 to} R ₄ preferably comprises a cation structure represented by the following formula (a) or (b) and an anionic component, or is represented by (c) or (d). Preferably, the zwitterion structure is

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 of an alkyl group having 1 to 10 carbon atoms, an aryl group, and a fluorine-substituted alkyl group. m is an integer of 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 of an alkyl group having 1 to 10 carbon atoms, an aryl group, and a fluorine-substituted alkyl group. m is an integer of 1 to 10.

On the other hand, the anion component is not particularly limited, and for example, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH _{3 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) _{^{PO 4 -, (C 2 H}} 5) 2 PO 4 -, C 2 H 5 OSO 3 -, C 6 H 13 OSO 3 -, C 8 H 17 OSO 3 -, CH 3 (OC 2 H 4) 2 OSO 3 _{^{-, C 6 H 4 (CH}} 3) SO 3 -, (C 2 F 5) 3 PF 3 -, CH 3 CH (OH) COO -, _{and, (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 represent any of an alkyl group having 1 to 10 carbon atoms, an aryl group, and 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 to 10, and p is an integer of 1 to 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 represent any one of an alkyl group having 1 to 10 carbon atoms, an aryl group, and 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 to 10, and p is an integer of 1 to 6.

  Since such an ionic group-containing silicone contains a silicone chain, it is stored in a high-temperature environment with the pressure-sensitive adhesive layer attached to the surface of an adherend (for example, a polarizing plate) due to the low surface free energy of the silicone chain. Even in this case, the ionic group-containing silicone does not penetrate into the adherend (from the surface of the adherend to the inside of the adherend) and tends to remain on the surface of the pressure-sensitive adhesive layer. The properties are stable, the antistatic performance is maintained for a long time, and it can be suitably used as an antistatic agent.

  Specific examples of the ionic group-containing silicone include, for example, commercially available product names X-40-2450 and X-40-2750 (all manufactured by Shin-Etsu Chemical Co., Ltd.). These compounds may be used alone or as a mixture of two or more.

  The content of the ionic group-containing silicone is set to 100 parts by mass of an adhesive polymer (a main polymer, for example, a (meth) acryl-based polymer, a urethane-based polymer, a silicone-based polymer, etc.) constituting the pressure-sensitive adhesive composition. On the other hand, it is 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, and most preferably 0.04 to 4.0 parts by mass. 8 parts by mass. When it is within the above range, even when the pressure-sensitive adhesive sheet of the present invention is stuck to an optical member or the like and stored in a high-temperature environment, the antistatic property, the stability over time of the peeling voltage, and the light peeling property (removability) (Removability) can be satisfied. In order to satisfy the stain resistance, the amount is preferably 0.01 to 5.5 parts by mass with respect to 100 parts by mass of the adhesive polymer.

<Oxyalkylene group-containing compound>
The pressure-sensitive adhesive composition of the present invention preferably contains an oxyalkylene group-containing compound, and more preferably contains an organopolysiloxane having an oxyalkylene chain, and more preferably contains an organopolysiloxane having an oxyalkylene main chain. More preferably, It is presumed that the use of the organopolysiloxane reduces the surface free energy of the surface of the pressure-sensitive adhesive, thereby realizing light peeling.

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, a known organopolysiloxane having a polyoxyalkylene main chain can be used as appropriate, but is preferably represented by the following formula (2).

In the above formula (2), R ₁ and / or R ₂ have 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, _one of R _{1 and} R ₂ may be a hydroxyl group, or may be an alkyl group or an alkoxy group, and a functional group in which a part of the alkyl group or the alkoxy group is substituted with a hetero atom. It may be. n is an integer of 1 to 300.

  As the organopolysiloxane, one having a siloxane-containing site (siloxane site) as a main chain and an oxyalkylene chain bonded to the terminal of the main chain is used. It is presumed that the use of the organosiloxane having an oxyalkylene chain balances the compatibility with the (meth) acrylic polymer, the antistatic component, and the like, and realizes light peeling.

Further, as the organopolysiloxane in the present invention, for example, the following configuration 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, and an oxyalkylene chain. Examples thereof include a propylene group and an oxybutylene group, and among them, an oxyethylene group and an oxypropylene group are preferable. When R ₁ and R ₂ both have an oxyalkylene chain, they may be the same or different.

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

  Further, the terminal of the oxyalkylene chain may be an alkoxy group or a hydroxyl group, and among them, an alkoxy group is more preferable. When a separator is bonded to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface, the organopolysiloxane having a hydroxyl group at the end thereof interacts with the separator, and the adhesion (peeling) when the separator is peeled off from the surface of the pressure-sensitive adhesive layer. Power may rise.

  N is an integer of 1 to 300, preferably 10 to 200, and more preferably 20 to 150. When n is within the above range, the compatibility with the base polymer is balanced, which is a preferable embodiment. Further, the molecule may have a reactive substituent such as a (meth) acryloyl group, an allyl group or a hydroxyl group. The organopolysiloxanes may be used alone or as a mixture of two or more.

  Specific examples of the organopolysiloxane having an oxyalkylene chain in the main chain include, for example, commercially available products having trade names of X-22-4952, X-22-4272, X-22-6266, KF-6004, KF-889 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), BY16-201, SF8427 (above, manufactured by Dow Corning Toray), IM22 (manufactured by Asahi Kasei Wacker Inc.), and the like. These compounds may be used alone or as a mixture 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, it is also possible to use an organosiloxane having an oxyalkylene chain in the side chain. In a more preferred embodiment, an organosiloxane having an oxyalkylene chain is used. As the organopolysiloxane, a known organopolysiloxane having a polyoxyalkylene side chain can be used as appropriate, but is preferably represented by the following formula (3).

In the formula (3), 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 to 1000. However, m and n do not become 0 at the same time. a and b are integers of 0-100. However, a and b do not become 0 at the same time. )

Further, as the organopolysiloxane in the present invention, for example, the following configuration can be used. Specifically, R ₁ in the formula is a monovalent group exemplified by an alkyl group such as a methyl group, an ethyl group and a propyl group, an aryl group such as a phenyl group and a tolyl group, or an aralkyl group such as a benzyl group and a phenethyl group. It is an organic group and each may have a substituent such as a hydroxyl group. As R ₂ , R ₃ and R _4, an alkylene group having 1 to 8 carbon atoms such as a methylene group, an ethylene group and a propylene group can be used. Here, R ₃ and R ₄ are different alkylene groups, and R ₂ may be the same as or different from R ₃ or R ₄ . One of R ₃ and R ₄ is an ethylene group or a propylene group in order to increase the concentration of an antistatic component (for example, an ionic group-containing silicone) that can be dissolved in the polyoxyalkylene side chain. Is preferred. R ₅ may be a monovalent organic group exemplified by an alkyl group such as a methyl group, an ethyl group and a propyl group or an acyl group such as an acetyl group and a propionyl group, each having a substituent such as a hydroxyl group. It may be. These compounds may be used alone or as a mixture of two or more. In addition, the molecule may have a reactive substituent such as a (meth) acryloyl group, an allyl group, and a hydroxyl group. Among the organosiloxanes having a polyoxyalkylene side chain, an organosiloxane having a polyoxyalkylene side chain having a hydroxyl group terminal is preferable because it is presumed that the compatibility is easily balanced.

  Specific examples of the organosiloxane having an oxyalkylene chain in the side chain include, for example, commercially available trade names KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, and KF-615A. -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 (all 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 (Toray Da Corning), 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, BYK-UV3570 (manufactured by BYK Japan KK) and the like. These compounds may be used alone or as a mixture of two or more.

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

  The pressure-sensitive adhesive composition may contain an oxyalkylene group-containing compound containing no organopolysiloxane. By containing the compound in the pressure-sensitive adhesive, a pressure-sensitive adhesive having excellent wettability to an adherend can be obtained.

  Specific examples of the oxyalkylene group-containing compound not containing the organopolysiloxane include, for example, polyoxyalkylene alkylamine, polyoxyalkylene diamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkyl phenyl ether Nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkyl allyl ether, and polyoxyalkylene alkyl phenyl allyl ether; polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether phosphates, polyoxyalkylene alkyl ethers Oxyalkylene alkyl phenyl ether sulfate, polyoxyalkylene alkyl phenyl ether phosphate ester Anionic surfactants such as salts; other cationic surfactants having a polyoxyalkylene chain (polyalkylene oxide chain), amphoteric surfactants, and polyether compounds having a polyoxyalkylene chain (and derivatives thereof) And acrylic compounds having a polyoxyalkylene chain (and derivatives thereof). Moreover, you may mix | blend a polyoxyalkylene chain containing monomer 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 compound having a polyoxyalkylene chain (polyether component) include a polypropylene glycol (PPG) -polyethylene glycol (PEG) block copolymer, a PPG-PEG-PPG block copolymer, And block copolymers of PEG-PPG-PEG. Derivatives of the polyether compound having a polyoxyalkylene chain include oxypropylene group-containing compounds having a terminal etherification (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.), and oxypropylene having a terminal acetylation. Group-containing compounds (such as terminally acetylated PPG).

  Further, specific examples of the acrylic compound having a polyoxyalkylene chain include a (meth) acrylate polymer having an oxyalkylene group. As the oxyalkylene group, the addition mole number of the oxyalkylene unit is preferably from 1 to 50, more preferably from 2 to 30, and still more preferably from 2 to 20, from the viewpoint of coordination of the ionic group-containing silicone. Further, the terminal of the oxyalkylene chain may be substituted with a hydroxyl group, an alkyl group, a phenyl group, or the like.

  The (meth) acrylate polymer having an oxyalkylene group is preferably a polymer containing, as a monomer unit (component), an alkylene oxide (meth) acrylate. Specific examples of the alkylene oxide (meth) acrylate For example, as the ethylene glycol group-containing (meth) acrylate, for example, methoxy-polyethylene glycol (meth) acrylate type such as methoxy-diethylene glycol (meth) acrylate, methoxy-triethylene glycol (meth) acrylate, ethoxy-diethylene glycol ( Ethoxy-polyethylene glycol (meth) acrylate type such as meth) acrylate, ethoxy-triethylene glycol (meth) acrylate, butoxy-diethylene glycol (meth) acrylate, Butoxy-polyethylene glycol (meth) acrylate type such as xy-triethylene glycol (meth) acrylate, phenoxy-polyethylene glycol (meth) acrylate type such as phenoxy-diethylene glycol (meth) acrylate, phenoxy-triethylene glycol (meth) acrylate, Examples thereof include methoxy-polypropylene glycol (meth) acrylate such as 2-ethylhexyl-polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (meth) acrylate, and methoxy-dipropylene glycol (meth) acrylate.

  Further, other monomer units (components) other than the alkylene oxide (meth) acrylate may be used as the monomer units (components). 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, and 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) A) acrylates and / or methacrylates having an alkyl group having 1 to 14 carbon atoms, such as acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate; And the like.

  Further, as other monomer units (components) other than the alkylene oxide (meth) acrylate, carboxyl group-containing (meth) acrylate, phosphate group-containing (meth) acrylate, cyano group-containing (meth) acrylate, 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- Acryloyl morpholine, vinyl ethers and the like can be used as appropriate.

  In a more preferred embodiment, the compound containing a polyoxyalkylene chain that does not contain an organopolysiloxane is a compound having a (poly) ethylene oxide chain at least in part. By blending the (poly) ethylene oxide chain-containing compound, the compatibility between the base polymer and the antistatic component is improved, bleeding to the adherend is suitably suppressed, and a low-staining adhesive composition is obtained. Can be In particular, when a block copolymer of PPG-PEG-PPG is used, a pressure-sensitive adhesive excellent in low contamination can be obtained. As the polyethylene oxide chain-containing compound, the mass of the (poly) ethylene oxide chain in the entire polyoxyalkylene chain-containing compound not containing the organopolysiloxane is preferably 5 to 90% by mass, more preferably 5 to 85% by mass. %, More preferably 5 to 80% by weight, and most preferably 5 to 75% by weight.

  As the molecular weight of the polyoxyalkylene chain-containing compound containing no organopolysiloxane, those having a number average molecular weight (Mn) of 50,000 or less are suitable, preferably 200 to 30,000, more preferably 200 to 10,000, and usually 200 to 5000 are suitably used. If Mn is too large, the compatibility with the acrylic polymer is reduced, and the pressure-sensitive adhesive layer tends to whiten. If Mn is less than 200, contamination by the polyoxyalkylene compound may easily occur. Here, Mn refers to a value in terms of polystyrene obtained by GPC (gel permeation chromatography).

  Specific examples of commercially available products of the polyoxyalkylene chain-containing compound not containing the organopolysiloxane include, for example, Adecapluronic 17R-4, Adecapluronic 25R-2 (all of which are manufactured by ADEKA), and 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 ( As mentioned above, Daiichi Kogyo Seiyaku Co., Ltd.).

  The content of the oxyalkylene group-containing compound is 100 parts by mass of an adhesive polymer (a main polymer, for example, a (meth) acryl-based polymer, a urethane-based polymer, a silicone-based polymer, etc.) constituting the pressure-sensitive adhesive composition. 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. It is preferable for the pressure-sensitive adhesive sheet of the present invention to have both the antistatic property and the light peeling property (removability) easily within the above range.

<Crosslinking agent>
In the pressure-sensitive adhesive sheet (surface protective film) of the present invention, the pressure-sensitive adhesive composition preferably contains a crosslinking agent. In the present invention, the pressure-sensitive adhesive composition can be used to form a pressure-sensitive adhesive layer. For example, when the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth) acrylic polymer, the constitutional unit, the composition ratio of the (meth) acrylic polymer, the selection and the addition ratio of the crosslinking agent, and the like are appropriately determined. By controlling and crosslinking, a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) having more excellent heat resistance can be obtained.

  As the crosslinking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine-based resin, an aziridine derivative, a metal chelate compound, or the like may be used. In particular, the use of an isocyanate compound is a preferred embodiment. Further, these compounds may be used alone or in combination of two or more.

  Examples of the isocyanate compound include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI) and dimer acid diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), Alicyclic isocyanates such as 3-bis (isocyanatomethyl) cyclohexane, aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate and xylylene diisocyanate (XDI), and the above isocyanate compound Allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, Reton'imin bond, polyisocynate modified products thereof obtained by modifying the like oxadiazinetrione bond. For example, as commercial products, trade names Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (above, manufactured by Takeda Pharmaceutical Co., Ltd.), Sumidur T80, Sumidur L, Desmodur N3400 (above, Sumika Bayer Urethane) Corporation), Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (all manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like. These isocyanate compounds may be used alone or as a mixture of two or more, and it is also possible to use a bifunctional isocyanate compound and a trifunctional or more functional isocyanate compound in combination. By using a cross-linking agent in combination, it is possible to achieve both tackiness and repulsion resistance (adhesion to a curved surface), and it is possible to obtain a pressure-sensitive adhesive sheet having more excellent adhesion reliability.

  When the isocyanate compound (a bifunctional isocyanate compound and a trifunctional or higher functional isocyanate compound) is used in combination, the compounding ratio (mass ratio) of both compounds is [bifunctional isocyanate compound] / [3 Or more isocyanate compound] (weight ratio) is preferably 0.1 / 99.9 to 50/50, more preferably 0.1 / 99.9 to 20/80, and 0.1 / 99. 9.9-10 / 90 is more preferable, 0.1 / 99.9-5 / 95 is more preferable, and 0.1 / 99.9-1 / 99 is most preferable. By adjusting and compounding within the above range, a pressure-sensitive adhesive layer having excellent tackiness and resilience resistance is obtained, which is a preferable embodiment.

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

  Examples of the melamine-based resin include hexamethylolmelamine. Examples of the aziridine derivative include HDU, TAZM, and TAZO (trade names, manufactured by Mutual Pharmaceutical Co., Ltd.) as commercial products.

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

  The content of the crosslinking agent used in the present invention is, for example, preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 15 parts by mass based on 100 parts by mass of the (meth) acrylic polymer. More preferably, it is more preferably 0.5 to 10 parts by mass, and most preferably 1 to 6 parts by mass. When the content is less than 0.01 parts by mass, the crosslinking formation by the crosslinking agent becomes insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer becomes small, and sufficient heat resistance may not be obtained. It tends to cause glue 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 wetting on the adherend (for example, a polarizing plate) becomes insufficient, and the adherend and the adhesive It tends to cause blisters generated between the layer and the pressure-sensitive adhesive composition layer. Furthermore, when the amount of the cross-linking agent is large, there is a tendency that the peeling charging characteristics are reduced. These cross-linking agents may be used alone or in combination of two or more.

  The pressure-sensitive adhesive composition may further contain a crosslinking catalyst for causing any of the above-mentioned crosslinking reactions to proceed more effectively. Examples of such a crosslinking catalyst include tin catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, iron tris (acetylacetonato), iron tris (hexane-2,4-dionato), and 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 (tridecane-6,8-dionato) iron, tris (1-phenylbutane-1, -Dionato) iron, tris (hexafluoroacetylacetonato) iron, tris (ethyl acetoacetate) iron, tris (acetoacetate-n-propyl) iron, tris (isopropylacetoacetate) iron, tris (acetoacetate-n-butyl) ) Iron, tris (acetoacetate-sec-butyl) iron, tris (acetoacetate-tert-butyl) iron, tris (methyl propionyl acetate) iron, tris (ethyl propionyl acetate) iron, tris (propionyl acetate-n-propyl) Iron, tris (propionyl acetate-isopropyl) iron, tris (propionyl acetate-n-butyl) iron, tris (propionyl acetate-sec-butyl) iron, tris (propionyl acetate-tert-butyl) iron, tris (benzyl acetoacetate) iron , Tris (dimethyl malonate) iron, tris (diethyl malonate) iron, trimethoxyiron And iron-based catalysts such as triethoxyiron, triisopropoxyiron and ferric chloride. These crosslinking catalysts may be used alone or in combination of two or more.

  Although the content of the crosslinking catalyst is not particularly limited, for example, the content is preferably about 0.0001 to 1 part by mass, preferably 0.001 to 0.5 part by mass, based on 100 parts by mass of the (meth) acrylic polymer. Parts by mass are more preferred. Within the above range, the rate of the crosslinking reaction when the pressure-sensitive adhesive layer is formed is high, and the pot life of the pressure-sensitive adhesive composition is long, which is a preferable embodiment.

  Further, the pressure-sensitive adhesive composition may contain a compound that causes keto-enol tautomerism. For example, in a pressure-sensitive adhesive composition containing a cross-linking agent or a pressure-sensitive adhesive composition that can be used by blending a cross-linking agent, an embodiment containing the compound that causes keto-enol tautomerism can be preferably adopted. Thereby, an effect of suppressing an excessive increase in viscosity and gelation of the pressure-sensitive adhesive composition after blending the cross-linking agent and extending a pot life of the pressure-sensitive adhesive composition can be realized. When at least an isocyanate compound is used as the cross-linking agent, it is particularly significant to include a compound that causes keto-enol tautomerism. This technique can be preferably applied, for example, when the pressure-sensitive adhesive composition is in an organic solvent solution or solventless form.

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

  The content of the compound causing the keto-enol tautomerism can be, for example, 0.1 to 20 parts by mass, and usually 0.5 to 15 parts by mass, based on 100 parts by mass of the (meth) acrylic polymer. It is appropriate to use parts by mass (for example, 1 to 10 parts by mass). If the amount of the compound is too small, it may be difficult to exert a sufficient use effect. On the other hand, if the compound is used more than necessary, it may remain in the pressure-sensitive adhesive layer and reduce cohesion.

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

<Adhesive layer and adhesive sheet (surface protection film)>
The pressure-sensitive adhesive sheet of the present invention is one in which the pressure-sensitive adhesive layer is formed on at least one surface of a base film. At that time, crosslinking of the pressure-sensitive adhesive composition is generally performed after application of the pressure-sensitive adhesive composition. It is also possible to transfer the pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition after crosslinking to a substrate film or the like.

  The method for forming the pressure-sensitive adhesive layer on the substrate film is not particularly limited. For example, the pressure-sensitive adhesive composition (solution) is applied to the substrate film, and the polymerization solvent and the like are dried and removed to form the pressure-sensitive adhesive layer. It is produced by forming on a base film. Thereafter, curing may be performed for the purpose of adjusting the migration of components of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. Further, when preparing the pressure-sensitive adhesive sheet by applying the pressure-sensitive adhesive composition on the substrate film, one or more solvents other than the polymerization solvent in the pressure-sensitive adhesive composition, so that the pressure-sensitive adhesive composition can be uniformly applied on the substrate film. May be newly added.

  In addition, as a method for forming the pressure-sensitive adhesive layer when producing the pressure-sensitive adhesive sheet of the present invention, a known method used for producing pressure-sensitive 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 prepared so that the pressure-sensitive adhesive layer has a thickness of 3 to 100 μm, preferably about 5 to 50 μm. It is preferable that the thickness of the pressure-sensitive adhesive layer be within the above-mentioned range because a proper balance between removability and adhesiveness can be easily obtained.

  Further, the total thickness of the pressure-sensitive adhesive sheet of the present invention is preferably from 8 to 300 μm, more preferably from 10 to 200 μm, and most preferably from 20 to 100 μm. When it is in the above range, the adhesive properties (removability, adhesiveness, etc.), workability, and appearance properties are excellent, which is a preferable embodiment. In addition, the said total thickness means the total of the thickness containing all the layers, such as a base material film, an adhesive layer, and other layers.

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

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

  The thickness of the separator is usually about 5 to 200 μm, preferably about 10 to 100 μm. It is preferable for it to be in the above-mentioned range because the workability of laminating to the pressure-sensitive adhesive layer and the workability of peeling from the pressure-sensitive adhesive layer are excellent. The separator, if necessary, silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, release and antifouling treatment with silica powder, etc., coating type, kneading type, evaporation type For example, antistatic treatment such as antistatic treatment can be performed.

  Further, in the pressure-sensitive adhesive sheet of the present invention, it is preferable that the ionic group-containing silicone is present (applied) on a surface of the separator that comes into contact with the pressure-sensitive adhesive layer (see FIG. 1). When the ionic group-containing silicone is present (applied, forming a coating film) on the surface of the separator that comes into contact with the pressure-sensitive adhesive layer, so that the separator is attached to the pressure-sensitive adhesive layer. The ionic group-containing silicone is transferred (transferred) to the surface of the pressure-sensitive adhesive layer from the surface of the separator, and the pressure-sensitive adhesive layer is adhered to the surface of an adherend (for example, a polarizing plate) under a high-temperature environment. Even when stored, the ionic group-containing silicone does not penetrate into the adherend (from the surface of the adherend to the inside of the adherend), the peeling charge characteristics are stable even with time, and the antistatic performance is long-term Is maintained, which is a preferred embodiment.

<Optical members>
It is preferable that the optical member of the present invention is attached (protected) by the adhesive sheet. Since the pressure-sensitive adhesive sheet has excellent antistatic properties and stability over time of a peeling voltage, it can be used for surface protection applications (surface protection films) at the time of processing, transportation, shipping, and the like. It is useful for protecting surfaces. In particular, since it can be used for plastic products that easily generate static electricity, it is very useful for antistatic applications in optical and electronic component-related technical fields where charging is a particularly serious problem.

  Hereinafter, some examples related to the present invention will be described, but it is not intended to limit the present invention to those shown in the specific examples. Note that “parts” and “%” in the following description are based on mass unless otherwise specified. Also, the blending amounts (addition amounts) in the table are shown.

  Further, 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) was measured using a GPC device (HLC-8220GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.
Sample concentration: 0.2% by mass (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column: TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column: TSKgel SuperH-RC (1)
Detector: Differential refractometer (RI)
The weight average molecular weight was determined in terms of polystyrene.

<Measurement of initial peeling voltage>
The pressure-sensitive adhesive sheet 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, a polarizing plate (SEG1423DU polarizing plate, manufactured by Nitto Denko Corporation, width: 70 mm, length) bonded to a glass plate : 100 mm) with a hand roller so that one end of the pressure-sensitive adhesive sheet protruded 30 mm from the end of the polarizing plate.
After leaving this sample in an environment of 23 ° C. × 50% RH for one day, as shown in FIG. 2, it was set at a predetermined position on a sample fixing table 30 having a height of 20 mm. The end of the pressure-sensitive adhesive sheet (surface protective film) 1 protruding 30 mm from the polarizing plate 20 was fixed to an automatic winding machine (not shown), and peeled at a peel angle of 150 ° and a peel speed of 30 m / min. The potential of the surface of the adherend (polarizing plate) generated at this time is fixed at a position 30 mm in height from the center of the polarizing plate 20 (model “STATIRON DZ-4” manufactured by Shisido Electrostatic Co., Ltd.). )), The "initial peeling voltage" was measured. The measurement was performed in an environment of 23 ° C. and 50% RH.

<Measurement of peeling voltage at 70 ° C>
The pressure-sensitive adhesive sheet 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, a polarizing plate (SEG1423DU polarizing plate, manufactured by Nitto Denko Corporation, width: 70 mm, length) bonded to a glass plate : 100 mm) with a hand roller so that one end of the pressure-sensitive adhesive sheet protruded 30 mm from the end of the polarizing plate.
After leaving this sample in an environment of 70 ° C. for 120 hours, as shown in FIG. 2, it was set at a predetermined position on a sample fixing table 30 having a height of 20 mm. The end of the pressure-sensitive adhesive sheet (surface protective film) 1 protruding 30 mm from the polarizing plate 20 was fixed to an automatic winding machine (not shown), and peeled at a peel angle of 150 ° and a peel speed of 30 m / min. The potential of the surface of the adherend (polarizing plate) generated at this time is fixed at a position 30 mm in height from the center of the polarizing plate 20 (model “STATIRON DZ-4” manufactured by Shisido Electrostatic Co., Ltd.). )), The “70 ° C. storage peeling voltage” was measured. The measurement was performed in an environment of 23 ° C. and 50% RH.

  The initial peeling voltage and the 70 ° C storage peeling voltage (kV) (absolute value) in the present invention are preferably 0.55 or less, more preferably 0.5 or less, and Preferably, it is 0.45 or less. When it is within the above range, the pressure-sensitive adhesive sheet initially peeled off after storage at 70 ° C. for 120 hours is not charged, and has excellent antistatic properties, excellent peeling charging properties over time, and further excellent workability. .

<Presence of contamination (stain resistance)>
After 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, bubbles were formed on a TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm). The sample was pressure-bonded with a hand roller while being put in, to produce an evaluation sample. 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 bubbles on the surface of the adherend at that time were visually observed. The evaluation was evaluated as ○ when no air bubble trace was observed, and as × when air bubble trace was observed.

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

<Preparation of acrylic polymer (2)>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 91 parts by mass of 2-ethylhexyl acrylate (2EHA), 9 parts by mass of 4-hydroxybutyl acrylate (4HBA), and acrylic acid (AA) 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 with gentle stirring, and the liquid in the flask was charged. The polymerization reaction was carried out for 6 hours while maintaining the temperature at about 65 ° C. to prepare an acrylic polymer (2) solution (40% by mass). The weight average molecular weight (Mw) of the acrylic polymer (2) was 540,000.

<Example 1>
(Preparation of acrylic pressure-sensitive adhesive solution)
The acrylic polymer (1) solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass (100 parts by mass of solid content) of the solution was added to an ionic group-containing silicone (X-40-2450, Shinetsu Chemical Industry Co., Ltd.) diluted to 10% with ethyl acetate (5 parts by mass (solids content: 0.5 parts by mass)), as a crosslinking agent, isocyanurate of hexamethylene diisocyanate which is a trifunctional isocyanate compound (manufactured by Tosoh Corporation) , Coronate HX), 2 parts by mass (solids content: 2 parts by mass), 3 parts by mass (solids content: 0.03 parts by mass) of dibutyltin dilaurate (1% by mass ethyl acetate solution) as a crosslinking catalyst, and mixing and stirring were performed. An acrylic adhesive solution was prepared.

(Preparation of antistatic treatment film)
Antistatic by diluting 10 parts by weight of an antistatic agent (Microsolver RMd-142, manufactured by Solvex, mainly composed of tin oxide and polyester resin) with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol. An agent solution was prepared.
The obtained antistatic agent solution was applied to 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 remove the antistatic layer (thickness). (0.2 μm) to form an antistatic treatment film.

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

<Example 2>
An acrylic polymer (2) was used in place of the acrylic polymer (1) used in Example 1, and an ionic group-containing silicone X-40-2750 was used instead of the ionic group-containing silicone X-40-2450. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the adhesive sheet was used.

<Example 3>
An acrylic polymer (2) was used in place of the acrylic polymer (1) used in Example 1, and 0.5 part by mass of an oxyalkylene group-containing compound KF353 (manufactured by Shin-Etsu Chemical Co., Ltd.) containing organopolysiloxane was added. Then, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

<Example 4>
In place of the acrylic polymer (1) used in Example 1, an acrylic polymer (2) was used, and an oxyalkylene group-containing compound containing no organopolysiloxane, Latemul PD-420 (manufactured by Kao Corporation) 0.2 A part by weight was added, and a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1.

<Examples 5 to 7>
In place of the acrylic polymer (1) used in Example 1, an acrylic polymer (2) was used, and X-40-2450 was used in the same manner as in Example 1 by using the amount of addition described in the table. An adhesive sheet was produced.

<Example 8>
(Preparation of urethane-based adhesive solution)
As the polyol, 85 parts by mass of Preminol S3011 (manufactured by Asahi Glass Co., Ltd., Mn = 10000) which is a polyol having three hydroxyl groups, and Sannics GP3000 (manufactured by Sanyo Chemical Co., Ltd., Mn = 3000) 13 which is a polyol having three hydroxyl groups13 Parts by mass, 2 parts by mass of Sannics GP1000 (manufactured by Sanyo Chemical Industries, Mn = 1000) which is a polyol having three hydroxyl groups, 18 parts by mass of an isocyanate compound (Coronate HX: C / HX, manufactured by Nippon Polyurethane Co., Ltd.) as a crosslinking agent 0.04 parts by mass of iron (III) acetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.5 parts by mass of ionic group-containing silicone X-40-2450 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a catalyst, and a diluting solvent 210 parts by mass of ethyl acetate were blended to obtain a urethane-based pressure-sensitive adhesive solution. Then, in the same manner as in Example 1, a pressure-sensitive adhesive sheet was prepared in which the heating conditions and the like and the thickness of the obtained pressure-sensitive adhesive layer were adjusted.

<Example 9>
(Preparation of silicone-based pressure-sensitive adhesive solution)
As a silicone-based adhesive, "X-40-3229" (solid content: 60% by mass, manufactured by Shin-Etsu Chemical Co., Ltd.) is 100 parts by mass in solid content, and as a platinum catalyst, "CAT-PL-50T" (Shin-Etsu Chemical Co., Ltd.) 0.5 parts by mass), 0.5 parts by mass of silicone having an ionic group X-40-2450 (manufactured by Shin-Etsu Chemical Co., Ltd.), and 100 parts by mass of toluene as a solvent to obtain a silicone-based pressure-sensitive adhesive solution. . Then, in the same manner as in Example 1, a pressure-sensitive adhesive sheet was prepared in which the heating conditions and the like and the thickness of the obtained pressure-sensitive adhesive layer were adjusted.

<Comparative Examples 1-4>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 2 except that the ionic compound containing the ionic group used in Example 2 was used instead of the ionic compound described in Table 1.

<Comparative Example 5>
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 3, except that EMIFSI was used instead of the ionic group-containing silicone used in Example 3.

  The pressure-sensitive adhesive sheets according to the examples and comparative examples were subjected to the above-described blending contents, various measurements and evaluations, and the results are shown in Table 1. The abbreviations in Table 1 are described below.

[Oxyalkylene group-containing compound]
KF353: organopolysiloxane having an oxyalkylene chain (HLB value: 10), manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KF-353
PD420: oxyalkylene group-containing compound containing no organopolysiloxane (HLB value: 12.6), manufactured by Kao Corporation, trade name: Latemul PD-420

[Ionic compound (antistatic component)]
X-40-2450: ionic group-containing silicone, manufactured by Shin-Etsu Chemical Co., Ltd., active ingredient 55%
X-40-2750: Ionic group-containing silicone, manufactured by Shin-Etsu Chemical Co., Ltd., active ingredient 100%
LiTFSI: lithium bis (trifluoromethanesulfonyl) imide, alkali metal salt, manufactured by Tokyo Chemical Industry, 100% active ingredient
EMIFSI: 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide, ionic liquid, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., active ingredient 100%
BMPTFSI: 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide, ionic liquid, manufactured by Aldrich, active ingredient 100%
MTOATFSI: methyltrioctylammonium bis (trifluoromethanesulfonyl) imide, manufactured by Wako Pure Chemical Industries, 100% active ingredient

  From Table 1, it was confirmed that in all of the examples, the antistatic property and the stability over time of the peeling voltage were excellent. In addition, it was confirmed that when the compounding amount of the ionic group-containing silicone was adjusted to a desired range and compounded, the compound was excellent also in stain resistance (low stain resistance).

  On the other hand, from Table 1, in all the comparative examples, since an antistatic agent such as an ionic liquid was used instead of the ionic group-containing silicone, the antistatic properties and the stability over time of the peeling voltage were compared with those of the examples. It was confirmed that it was inferior. In particular, since the ionic group-containing silicone was not used, there was a case where a large increase in the peeling electrostatic voltage was observed over time, and the ionic compound contained in the pressure-sensitive adhesive layer permeated the polarizing plate surface over time. It is inferred.

  The pressure-sensitive adhesive sheet disclosed herein protects an optical member used as a component of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, or the like at the time of manufacturing or transporting the optical member. Is suitable as a surface protective film. In particular, a surface protection film (optical surface) applied to an optical member such as a polarizing plate (polarizing film), a wave plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light diffusion sheet, and a reflection sheet for a liquid crystal display panel. Useful as a protective film).

1: Adhesive sheet (surface protection film)
1 ': Adhesive sheet with separator (surface protection film)
10: Acrylic plate 11: Separator 12: Ionic group-containing silicone coating film 13: Adhesive layer 14: Substrate film 20: Polarizing plate 30: Sample holder 40: Potentiometer

Claims (7)

An adhesive composition comprising an adhesive polymer and an ionic group-containing silicone represented by the following formula (1).

(R _{1 to} R ₄ may be the same or different and include any of an alkyl group having 1 to 10 carbon atoms, an alkoxy group, an aryl group, an alicyclic group, a fluorine-substituted alkyl group, and an ionic group; One or more of R _{1 to} R ₄ contains an ionic group. N is an integer of 0 to 100.)   The pressure-sensitive adhesive composition according to claim 1, comprising an oxyalkylene group-containing compound.   The pressure-sensitive adhesive composition according to claim 1, comprising at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. At least one surface of the base film has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 3,
The pressure-sensitive adhesive sheet, wherein the ionic group-containing silicone is present inside and / or on the surface of the pressure-sensitive adhesive layer.   The pressure-sensitive adhesive sheet according to claim 4, wherein a separator is attached to a surface of the pressure-sensitive adhesive layer opposite to a surface that contacts the base film.   The pressure-sensitive adhesive sheet according to claim 5, wherein the ionic group-containing silicone is present on a surface of the separator that contacts the pressure-sensitive adhesive layer. An optical member comprising a pressure-sensitive adhesive sheet according to claim 4 or a pressure-sensitive adhesive sheet obtained by removing the separator from the pressure-sensitive adhesive sheet according to claim 5 or 6.

Images