JP6698133B2 - Adhesive composition, 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 protected by the pressure-sensitive adhesive sheet.

  The pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition of the present invention is intended to protect the surface of optical members such as polarizing plates, wave plates, retardation plates, optical compensation films, reflection sheets, and brightness enhancement films used in liquid crystal displays and the like. It is useful as a surface protective film used in.

  2. Description of the Related Art In recent years, when transporting optical components and electronic components and mounting them on a printed circuit board, they have been transported in a state in which individual components are wrapped in a predetermined sheet or a state in which an adhesive tape is attached. Above all, the surface protective film is particularly widely used in the field of optical and electronic parts.

  The surface protection film is generally attached to an adherend (protected object) via an adhesive applied to the support film side, and is used for the purpose of preventing scratches and stains generated during processing and transportation of the adherend. (Patent Document 1). For example, a panel of a liquid crystal display is formed by bonding optical members such as a polarizing plate and a wave plate to a liquid crystal cell via an adhesive. In these optical members, a surface protection film is attached via an adhesive to prevent scratches and stains that occur during processing and transportation of the adherend.

  When attached to an adherend (polarizing plate, etc.), the surface protective film causes unnecessary curl or unintentional curl (curling back) in the adherend (polarizing plate, etc.) to which the surface protective film is adhered. A phenomenon such as a phenomenon in which a flat-shaped object is entirely warped to one surface side, or a flat-shaped object is generally warped in a wavy manner.) Adjustability is required. If unnecessary curl or unintentional curl occurs, the handleability is poor, and for example, when attaching an adherend such as a polarizing plate to a liquid crystal cell, problems such as trapping of bubbles may occur.

  Further, when curling occurs in the plate-shaped adherend, a force associated with the curl acts in the shearing direction on the pressure-sensitive adhesive layer of the surface protective film attached to the adherend, and this force causes the adherence to occur. Since slippage, displacement and the like gradually occur between the body and the pressure-sensitive adhesive layer, improvement in shearing force is required.

JP, 9-165460, A

  Therefore, an object of the present invention is to form a pressure-sensitive adhesive sheet having excellent shearing force and capable of suppressing curling of an adherend when attached to an adherend in order to solve the problems in the conventional pressure-sensitive adhesive sheet. It is intended to provide a pressure-sensitive adhesive composition that can be used, the pressure-sensitive adhesive sheet, and an optical member obtained by applying the pressure-sensitive adhesive sheet for surface protection.

  That is, the pressure-sensitive adhesive composition of the present invention contains an onium salt having a melting point of 150° C. or lower, and a polymer having a glass transition temperature of 0° C. or lower as a base polymer, wherein the onium salt is a nitrogen-containing onium salt, At least one selected from the group consisting of a sulfur-containing onium salt and a phosphorus-containing onium salt, wherein the onium salt contains an onium cation having at least one alkyl group having 8 or more carbon atoms. ..

  The pressure-sensitive adhesive composition of the present invention preferably contains a compound having an alkylene oxide group having a number average molecular weight of 10,000 or less.

  In the pressure-sensitive adhesive composition of the present invention, the compound having an alkylene oxide group is preferably an organopolysiloxane having an alkylene oxide group.

  In the pressure-sensitive adhesive composition of the present invention, the polymer having a glass transition temperature of 0° C. or lower is preferably a (meth)acrylic polymer having a hydroxyl group and a carboxyl group.

The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition on one side or both sides of a support film, the pressure-sensitive adhesive layer having an adhesive area of 1 cm ² attached to a TAC polarizing plate. In addition, the shearing force when peeled in the shearing direction at a peeling speed of 0.06 m/min after sticking at 23° C. for 30 minutes is preferably 8.5 N/cm ² or more.

  The pressure-sensitive adhesive sheet of the present invention has an antistatic layer on one surface of the support film on the side opposite to the pressure-sensitive adhesive layer, the antistatic layer is polyanilinesulfonic acid as a conductive polymer component, a polyester resin as a binder, and It is preferably formed from an antistatic agent composition containing an isocyanate crosslinking agent as a crosslinking agent.

  In the pressure-sensitive adhesive sheet of the present invention, it is preferable that the antistatic composition further contains a fatty acid amide as a lubricant.

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

  Since the pressure-sensitive adhesive sheet formed from the pressure-sensitive adhesive composition of the present invention is excellent in shearing force, it is possible to suppress unnecessary curling and unintended curl in the adherend when it is attached to the adherend. It can and is useful.

Schematic diagram of potential measurement unit

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

<Overall structure of adhesive sheet (surface protection film)>
The pressure-sensitive adhesive sheet (surface protective film) of the present invention is generally in the form of a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive film, and the like, and in particular optical components (for example, a liquid crystal such as a polarizing plate and a wave plate). It is suitable as a surface protective film that protects the surface of an optical component during processing or transportation of an optical component used as a display panel constituent element). The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet is typically formed continuously, but is not limited to such a form, and a pressure-sensitive adhesive formed in a regular or random pattern such as dots or stripes. It may be an agent layer. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or a sheet.

  As a typical configuration example of the pressure-sensitive adhesive sheet (surface protective film) disclosed herein, those having a pressure-sensitive adhesive layer on one side or both sides of the support film (base material), or antistatic provided on one side of the support film. Examples thereof include a layer and an adhesive layer provided on the surface of the support film opposite to the antistatic layer. The pressure-sensitive adhesive sheet is used by sticking this pressure-sensitive adhesive layer to an adherend (a protection target, for example, the surface of an optical component such as a polarizing plate). The pressure-sensitive adhesive sheet before use (that is, before being adhered to an adherend) has a surface of the adhesive layer (adhesive surface to be adhered) protected by a release liner having a release surface on at least the adhesive layer side. It may have a different form. Alternatively, the pressure-sensitive adhesive sheet may be wound into a roll so that the pressure-sensitive adhesive layer comes into contact with the back surface of the support film (surface of the antistatic layer) to protect the surface.

<Adhesive composition>
The pressure-sensitive adhesive composition of the present invention comprises an onium salt having a melting point of 150° C. or lower, and a polymer having a glass transition temperature of 0° C. or lower as a base polymer, wherein the onium salt is a nitrogen-containing onium salt or a sulfur-containing sulfur. It is at least one selected from the group consisting of onium salts and phosphorus-containing onium salts, wherein the onium salt contains an onium cation having at least one alkyl group having 8 or more carbon atoms. The pressure-sensitive adhesive composition contains the onium salt having a melting point of 150° C. or lower, and the polymer having a glass transition temperature (Tg) of 0° C. or lower as a base polymer, as long as it can exhibit adhesiveness, It can be used without particular limitation. For example, acrylic adhesives, urethane adhesives, polyester adhesives, synthetic rubber adhesives, natural rubber adhesives, silicone adhesives and the like can be used. Among them, the acrylic pressure-sensitive adhesive is a preferable embodiment because the pressure-sensitive adhesive property can be easily controlled.

  In the present invention, the polymer having a glass transition temperature (Tg) of 0° C. or lower is preferably a (meth)acrylic polymer, and a (meth)acrylic polymer having a hydroxyl group and a carboxyl group. , And more preferable. By using a polymer having a glass transition temperature (Tg) of 0° C. or lower, it is possible to design a pressure-sensitive adhesive having excellent pressure-sensitive adhesive properties, and by using the (meth)acrylic polymer, it is possible to control the pressure-sensitive adhesive properties. Is easily possible, which is a preferable mode. Further, by using the (meth)acrylic polymer having the hydroxyl group and the carboxyl group, the hydroxyl group can easily control the crosslinking, and the carboxyl group improves the shearing force. In addition, it is possible to prevent an increase in adhesive strength over time, which is a preferred embodiment. In particular, by using the (meth)acrylic polymer having a hydroxyl group and a carboxyl group, the shearing force of the pressure-sensitive adhesive (layer) is improved, thereby bonding the pressure-sensitive adhesive to an adherend, Curling due to the adherend can be suppressed, and occurrence of slippage and displacement between the adhesive and the adherend (interface) can be suppressed, which is preferable.

  In the present invention, a polymer having a glass transition temperature (Tg) of 0° C. or lower is contained as a base polymer, and a polymer having a glass transition temperature (Tg) of 0° C. or lower is contained in 100% by mass of the base polymer. A more preferable aspect is 100% by mass. The (meth)acrylic polymer in the present invention means an acrylic polymer and/or a methacrylic polymer, and the (meth)acrylate means an acrylate and/or a methacrylate.

  Further, it is preferable that the (meth)acrylic polymer contains the hydroxyl group-containing (meth)acrylic monomer as a monomer component. By using the above-mentioned hydroxyl group-containing (meth)acrylic monomer, it becomes easier to control the crosslinking of the pressure-sensitive adhesive composition, thereby improving the wettability by flow and balancing the cohesive force and shearing force of the pressure-sensitive adhesive (layer). Will be easier to control. Further, when an antistatic agent is added to the pressure-sensitive adhesive, unlike a carboxyl group or a sulfonate group that can generally act as a crosslinking site, a hydroxyl group is suitable as an antistatic agent such as an onium salt having a melting point of 150° C. or lower. Since they have an interaction, they can also act favorably in terms of antistatic properties.

  In the present invention, the hydroxyl group-containing (meth)acrylic monomer is preferably contained in an amount of 0.5 to 15% by mass, more preferably 0. It is 6 to 7% by mass, more preferably 0.7 to 4.99% by mass, and most preferably 1.0 to 3.9% by mass. Within the above range, it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force or shearing force of the pressure-sensitive adhesive (layer), which is preferable. Further, in order to develop good charging characteristics with a smaller amount of the onium salt, it is more effective that the amount of the hydroxyl group-containing (meth)acrylic monomer is smaller.

  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. The hydroxyl group-containing (meth)acrylic monomer may be used alone or in combination of two or more as a monomer component.

  Further, the (meth)acrylic polymer preferably contains the carboxyl group-containing (meth)acrylic monomer as a monomer component. By using the carboxyl group-containing (meth) acrylic monomer, it is possible to suppress an increase in the adhesive force of the adhesive sheet (adhesive layer) over time, re-peelability, adhesive force increase preventive property, and workability. It is also preferable that it is excellent in cohesive force of the pressure-sensitive adhesive layer and also excellent in shearing force.

  In the present invention, the carboxyl group-containing (meth)acrylic monomer is preferably contained in an amount of 0.005 to 0.5 mass% with respect to the total amount of the monomer components constituting the (meth)acrylic polymer, and more preferably The amount is 0.006 to 0.4% by mass, more preferably 0.008 to 0.3% by mass, and most preferably 0.01 to 0.2% by mass. Within the above range, it is possible to suppress an increase in the adhesive force over time, and it is excellent in the removability, the adhesive force increase preventing property, and the workability. Further, it is preferable because the adhesive layer is excellent in shearing force as well as in cohesive force. When a large number of acid functional groups such as a carboxyl group having a large polar action are present, when an onium salt or the like having a melting point of 150° C. or less that can be used as an antistatic agent is blended, the acid functional group such as a carboxyl group and the onium salt are mixed. The interaction of salts and the like is unfavorable because it may hinder ionic conduction, reduce the conductivity efficiency, and prevent sufficient antistatic properties from being obtained.

  Examples of the carboxyl group-containing (meth)acrylic monomer include (meth)acrylic acid, carboxylethyl (meth)acrylate, carboxylpentyl (meth)acrylate, 2-(meth)acryloyloxyethylhexahydrophthalic acid, 2 -(Meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxy Examples thereof include polycaprolactone mono(meth)acrylate and 2-(meth)acryloyloxyethyl tetrahydrophthalic acid. The carboxyl group-containing (meth)acrylic monomer may be used alone or in combination of two or more as a monomer component.

  In the present invention, the (meth)acrylic polymer preferably uses a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a monomer component, and more preferably 4 to 14 carbon atoms. Is a (meth)acrylic monomer having an alkyl group. The (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms may be used alone, or two or more kinds may be used as a monomer component.

  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. Be done.

  Among them, when the pressure-sensitive adhesive sheet of the present invention is used as a surface protective film, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl. (Meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate and the like. A (meth)acrylate having an alkyl group having 6 to 14 carbon atoms is preferable. By using the (meth)acrylate having an alkyl group having 6 to 14 carbon atoms, it becomes easy to control the adhesive force to the adherend to be low and the removability becomes excellent.

  In the present invention, 50 to 99 mass% of the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms may be contained with respect to the total amount of monomer components constituting the (meth)acrylic polymer. It is more preferably 60 to 98.8% by mass, further preferably 70 to 98.6% by mass, and most preferably 80 to 98.4% by mass. Within the above range, the pressure-sensitive adhesive composition has appropriate wettability and is excellent in cohesive force of the pressure-sensitive adhesive (layer), which is preferable.

  Further, as another polymerizable monomer component, the glass transition temperature (Tg) is set to 0° C. or lower (usually −100° C. or higher) for the reason that the adhesive performance is easily balanced, and the (meth)acrylic polymer is used. A polymerizable monomer for adjusting the Tg and the releasability can be used within a range that does not impair the effects of the present invention.

  Other than the hydroxyl group-containing (meth)acrylic monomer, carboxyl group-containing (meth)acrylic monomer, and (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms, which are used in the (meth)acrylic polymer Other polymerizable monomers can be used without particular limitation as long as they do not impair the characteristics of the present invention. For example, cohesive strength/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, vinyl ether monomers, etc. A component having a functional group that functions as an adhesive (adhesion) force improving or cross-linking base point, a peeling force adjusting component such as an alkylene oxide group-containing monomer can be appropriately used. These polymerizable monomers may be used alone or in combination of two or more.

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

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

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

  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-dimethylaminopropyl acrylamide, N,N-dimethylaminopropyl methacrylamide, diacetone acrylamide, N-methyl (meth)acrylamide, N-isopropyl (meth)acrylamide , N-t-butyl(meth)acrylamide, N,N-dipropylacrylamide, N,N-diisopropyl(meth)acrylamide, N,N-dibutyl(meth)acrylamide, N-ethyl-N-methyl(meth)acrylamide , N-methyl-N-propyl(meth)acrylamide, N-methyl-N-isopropyl(meth)acrylamide, N-methylolacrylamide, diacetone acrylamide, N-vinylacetamide, N,N′-methylenebisacrylamide, N, N-diethylaminopropyl(meth)acrylamide, N,N-dipropylaminopropyl(meth)acrylamide, N,N-diisopropylaminopropyl(meth)acrylamide, N-ethyl-N-methylaminopropyl(meth)acrylamide, N- Methyl-N-propylaminopropyl(meth)acrylamide, N-methyl-N-isopropylaminopropyl(meth)acrylamide, N-vinylacetamide, N-vinyl-N-methylacetamide, N-methoxymethyl(meth)acrylamide, N -Ethoxyethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-vinylcaprolactam and the like can be mentioned.

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

  Examples of the amino group-containing monomer include aminoethyl (meth)acrylate, N,N-dimethylaminomethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and N,N-dimethylaminopropyl (meth). ) Acrylate, N,N-dimethylaminoisopropyl (meth)acrylate, N,N-dimethylaminobutyl (meth)acrylate, N,N-diethylaminomethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N -Ethyl-N-methylaminoethyl (meth)acrylate, N-methyl-N-propylaminoethyl (meth)acrylate, N-methyl-N-isopropylaminoethyl (meth)acrylate, N,N-dibutylaminoethyl (meth ) Acrylate, t-butylaminoethyl (meth)acrylate, (meth)acryloylmorpholine and the like.

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

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

  Examples of the alkylene oxide group-containing monomer include methoxy-diethylene glycol (meth)acrylate, methoxy-polyethylene glycol (meth)acrylate type such as methoxy-triethylene glycol (meth)acrylate, ethoxy-diethylene glycol (meth)acrylate, ethoxy-. Ethoxy-polyethylene glycol (meth)acrylate type such as triethylene glycol (meth)acrylate, butoxy-diethylene glycol (meth)acrylate, butoxy-polyethylene glycol (meth)acrylate type such as butoxy-triethylene glycol (meth)acrylate, phenoxy- Phenoxy-polyethylene glycol (meth)acrylate type such as diethylene glycol (meth)acrylate, phenoxy-triethylene glycol (meth)acrylate, 2-ethylhexyl-polyethylene glycol (meth)acrylate, nonylphenol-polyethylene glycol (meth)acrylate type, methoxy- Examples thereof include methoxy-polypropylene glycol (meth)acrylate type such as dipropylene glycol (meth)acrylate.

  In the present invention, the polymerizable monomer other than the carboxyl group-containing (meth)acrylic monomer, the hydroxyl group-containing (meth)acrylic monomer, and the (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms. Is preferably 0 to 40% by mass, and more preferably 0 to 30% by mass in the total amount of monomer components (total monomer components) constituting the (meth)acrylic polymer. By using the other polymerizable monomer within the above range, good interaction with an onium salt having a melting point of 150° C. or less which can be used as an antistatic agent, and good removability can be appropriately adjusted. ..

  When a nitrogen-containing monomer such as the amide group-containing monomer is used as the other polymerizable monomer as a monomer component of the (meth)acrylic polymer, it is preferably contained in an amount of 0.5 to 20% by mass. , More preferably 0.5 to 10% by mass, further preferably 1 to 4% by mass. By using the (meth)acrylic polymer containing the nitrogen-containing monomer, the cohesive force of the obtained pressure-sensitive adhesive (layer) can be improved, excellent shearing force can be expressed, and further curl control (curl controllability ) Is expected to increase. Further, curl controllability at high temperature can be improved, which is useful. Further, it is presumed that the onium salt having a melting point of 150° C. or less is coordinated with the nitrogen atom contained in the nitrogen-containing monomer, so that the onium salt is less likely to bleed and excellent shearing force can be realized. When the adhesive sheet is required to have a lower adhesive strength, the content of the nitrogen-containing monomer is preferably smaller.

  The weight average molecular weight (Mw) of the (meth)acrylic polymer is preferably 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 400,000 to 700,000. Is. If the Mw is less than 100,000, the adhesive force of the obtained pressure-sensitive adhesive layer becomes small, and adhesive residue tends to occur. On the other hand, when the Mw exceeds 5,000,000, the fluidity of the polymer is lowered and the adherend (for example, a polarizing plate which is an optical member) is insufficiently wetted, and the pressure-sensitive adhesive layer of the adherend and the pressure-sensitive adhesive sheet. (Adhesive composition layer) tends to cause blistering that occurs. In addition, Mw means what was obtained by measuring by the gel permeation chromatography method (GPC).

  Further, the polymer having a glass transition temperature (Tg) of 0° C. or lower (for example, the (meth)acrylic polymer) has a Tg of 0° C. or lower, preferably −10° C. or lower, and more preferably −40° C. C. or lower, more preferably −60° C. or lower (usually −100° C. or higher). When Tg is higher than 0° C., the polymer does not easily flow, and, for example, the adherend (for example, a polarizing plate that is an optical member) becomes insufficiently wet, and the adherend and the pressure-sensitive adhesive layer (pressure-sensitive adhesive composition) (Layer) tends to cause blisters that occur between. Further, by setting Tg to 0° C. or less, it becomes easy to obtain a pressure-sensitive adhesive composition having excellent wettability to an adherend and light peeling property. The Tg of the polymer having a glass transition temperature (Tg) of 0° C. or lower (for example, the (meth)acrylic polymer) can be adjusted within the above range by appropriately changing the monomer components and the composition ratio. ..

  The polymerization method of the polymer having a glass transition temperature (Tg) of 0° C. or less (for example, the (meth)acrylic polymer) used in the present invention is not particularly limited, and solution polymerization, emulsion polymerization, bulk polymerization Although it can be polymerized by a known method such as suspension polymerization, solution polymerization is a more preferable embodiment from the viewpoint of workability and characteristics such as low contamination of adherends. Further, the obtained polymer may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer and the like.

  The pressure-sensitive adhesive composition of the present invention contains an onium salt having a melting point of 150° C. or lower, and the onium salt is at least selected from the group consisting of a nitrogen-containing onium salt, a sulfur-containing onium salt, and a phosphorus-containing onium salt. It is one kind, and the onium salt contains an onium cation having at least one alkyl group having 8 or more carbon atoms. Use of the onium salt having a melting point of 150° C. or lower (preferably 100° C. or lower, more preferably 30° C. or higher and 60° C. or lower) facilitates dispersion in the base polymer, which is a preferred embodiment. Further, when the onium salt is at least one selected from the group consisting of nitrogen-containing onium salts, sulfur-containing onium salts, and phosphorus-containing onium salts, it becomes possible to exhibit excellent charging characteristics, and further, When the onium salt contains an onium cation having at least one alkyl group having 8 or more carbon atoms, it is possible to achieve both shearing property and charging property, which is preferable.

  The onium salt having a melting point of 150° C. or lower is preferably an onium cation having at least one alkyl group having 8 or more carbon atoms that constitutes the onium salt, preferably an alkyl group having 9 or more carbon atoms, and more preferably It is an onium cation having an alkyl group having 10 or more carbon atoms.

  Among the onium salts, as the nitrogen-containing onium salt, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-decyl-3-methylimidazolium hexa Fluorophosphate, 1-dodecyl-3-methylimidazolium iodide, 1-dodecyl-3-methylimidazolium bromide, 1-dodecyl-3-methylimidazolium hexafluorophosphate, 1-tetradecyl-3-methylimidazolium Hexafluorophosphate, 1-hexadecyl-3-methylimidazolium tetrafluoroborate, 1-hexadecyl-3-methylimidazolium hexafluorophosphate, 1-hexadecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1 -Octylpyridinium hexafluorophosphate, 1-octylpyridinium dodecylbenzenesulfonate, 1-octyl-3-methylpyridinium hexafluorophosphate, 1-octyl-4-methylpyridinium hexafluorophosphate, 1-nonylpyridinium hexafluorophosphate Fate, 1-dodecylpyridinium thiocyanate, 1-dodecyl-2-methylpyridinium hexafluorophosphate, 1-hexadecylpyridinium bis(trifluoromethanesulfonyl)imidomethyltrioctylammonium triflate, methyltrioctylammonium trifluoromethanesulfonate, tetra Examples include octyl ammonium bromide, hexadecyl trimethyl ammonium hexafluorophosphate, and the like.

  Among the onium salts, examples of the sulfur-containing onium salt include diethyltetradecylsulfonium hexafluorophosphate.

  Among the onium salts, examples of the phosphorus-containing onium salt include tetraoctylphosphonium bromide, trihexyltetradecylphosphonium bromide, tributylhexadecylphosphonium bromide, and the like.

  The content of the onium salt is preferably 0.1 to 4.9 parts by mass, more preferably 0.2 to 4 parts by mass, and 0.5 to 3 parts by mass with respect to 100 parts by mass of the base polymer. Is more preferable, and 0.7 to 1.4 parts by mass is the most preferable. Within the above range, it is easy to achieve both antistatic property and low contamination property, which is preferable.

  The pressure-sensitive adhesive composition of the present invention preferably contains a compound having an alkylene oxide group having a number average molecular weight (Mn) of 10,000 or less. By using the compound having an alkylene oxide group, it is possible to obtain a pressure-sensitive adhesive composition having excellent wettability to an adherend.

  Specific examples of the compound having an alkylene oxide group include, for example, polyoxyalkylene alkylamine, polyoxyalkylene diamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkylphenyl ether, polyoxyalkylene alkyl. Nonionic surfactants such as ethers, polyoxyalkylene alkyl allyl ethers, polyoxyalkylene alkyl phenyl allyl ethers; polyoxyalkylene alkyl ether sulfate ester salts, polyoxyalkylene alkyl ether phosphate ester salts, polyoxyalkylene alkyl phenyl ethers Anionic surfactants such as sulfate ester salts and polyoxyalkylene alkyl phenyl ether phosphate ester salts; Others, cationic surfactants having a polyalkylene oxide group (polyalkylene oxide chain), amphoteric surfactants, poly Examples include polyether compounds having alkylene oxide groups (and their derivatives), polyester compounds having polyalkylene oxide groups (and their derivatives), acrylic compounds having polyalkylene oxide groups (and their derivatives), and the like. Be done. Moreover, you may mix|blend with the said base polymer (for example, the said (meth)acrylic-type polymer) as a compound which has the said alkylene oxide group using the alkylene oxide group containing monomer. The compound having an alkylene oxide group may be used alone or in combination of two or more kinds.

  Specific examples of the polyether compound having an alkylene oxide group include a polypropylene glycol (PPG)-polyethylene glycol (PEG) block copolymer, a PPG-PEG-PPG block copolymer, and a PEG-PPG-PEG block. Examples thereof include copolymers. As the derivative of the polyether compound having an alkylene oxide group, an oxypropylene group-containing compound having an etherified terminal (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.), an oxypropylene group having an acetylated terminal is contained. Examples thereof include compounds (terminally acetylated PPG, etc.).

  Specific examples of the acrylic compound having an alkylene oxide group include (meth)acrylate polymers having an oxyalkylene group. As the oxyalkylene group, the addition mole number of the oxyalkylene unit is preferably 1 to 50, more preferably 2 to 30, and further preferably 2 to 20 from the viewpoint that the onium salt as an antistatic agent is coordinated. preferable. The terminal of the oxyalkylene group may be a hydroxyl group as it is, or may be substituted with an alkyl group, a phenyl group or the like.

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

  Further, as the monomer component, other monomer components other than the (meth)acrylic acid alkylene oxide 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. , 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, and acrylates and/or methacrylates having an alkyl group having 1 to 14 carbon atoms. Be done.

  Further, other monomer components other than the (meth)acrylic acid alkylene oxide include carboxyl group-containing (meth)acrylate, phosphoric acid 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-acryloylmorpholine, vinyl ether It is also possible to use a class or the like as appropriate.

  In a preferred embodiment, the compound having an alkylene oxide group is a compound having a (poly)ethylene oxide group at least in part. By blending the compound having a (poly)ethylene oxide group, the compatibility between the base polymer (for example, the (meth)acrylic polymer) and the antistatic component is improved, and bleeding to the adherend is appropriately suppressed. Thus, a low-staining pressure-sensitive adhesive composition is obtained. Above all, when a PPG-PEG-PPG block copolymer is used, a pressure-sensitive adhesive composition excellent in low stain resistance can be obtained. As the (poly)ethylene oxide group-containing compound, the mass of the (poly)ethylene oxide group in the entire compound is preferably 5 to 90% by mass, more preferably 5 to 85% by mass, and further preferably 5 to 80% by mass. % By weight, most preferably 5 to 75% by weight.

  As the molecular weight of the compound having an alkylene oxide group, the number average molecular weight (Mn) is preferably 10,000 or less, more preferably 200 to 8000, further preferably 300 to 6000, and particularly preferably 400 to 4000. When Mn is more than 10,000, the compatibility with the base polymer (for example, the (meth)acrylic polymer) is lowered, and the pressure-sensitive adhesive layer tends to be whitened. When Mn is less than 200, contamination with the compound having an alkylene oxide group may easily occur. In addition, Mn means the value of polystyrene conversion obtained by the gel permeation chromatography method (GPC) here.

  Further, specific examples of the above-mentioned compound having an alkylene oxide group as a commercial product include, for example, ADEKA Pluronic 17R-4, ADEKA Pluronic 25R-1, ADEKA Pluronic 25R-2 (above, manufactured by ADEKA), Emulgen 120 (above, Kao Corporation) and the like.

  In the present invention, the compound having an alkylene oxide group is preferably an organopolysiloxane having an alkylene oxide group. It is presumed that the use of the organopolysiloxane reduces the surface free energy of the pressure-sensitive adhesive surface and realizes light peeling at high speed peeling.

  As the organopolysiloxane, a known organopolysiloxane having an alkylene oxide group can be appropriately used. For example, as commercial products, trade names are X-22-4952, X-22-4272, X-22-6266, and KF. -6004, KF-889, 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 (above, Shin-Etsu Chemical Co., Ltd.), BY16-201, SF8427, 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 (above, Toray Dow Corning), IM22 (above Asahi Kasei Wacker), TSF-4440, TSF-4441, TSF-4445, TSF-4450, TSF-4446, TSF-4452, TSF-4460 ( As mentioned above, BYK-333, BYK-307, BYK-377, BYK-UV3500, BYK-UV3570 (above, manufactured by BYK-Chemie Japan), etc. are mentioned. These may be used alone or in combination of two or more.

  The organopolysiloxane used in the present invention preferably has an HLB (Hydrophile-Lipophile Balance) value of 1 to 16, and more preferably 3 to 14. When the HLB value is out of the above range, the adherence to the adherend becomes poor, which is not preferable.

  The content of the compound having an alkylene oxide group having a number average molecular weight of 10,000 or less is preferably 0.01 to 5 parts by mass, and more preferably 0.03 to 1 part by mass with respect to 100 parts by mass of the base polymer. Parts by mass, more preferably 0.05 to 0.5 parts by mass, most preferably 0.1 to 0.2 parts by mass. It is preferable for it to be in the above-mentioned range since both antistatic properties and light releasability (removability) are easily achieved at the same time. In addition, when the content is low, the effect of preventing bleeding of the antistatic component is reduced, and when the content is high, contamination by the compound having an alkylene oxide group itself tends to occur, which is not preferable.

  The pressure-sensitive adhesive composition of the present invention 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, in the case where the pressure-sensitive adhesive contains the (meth)acrylic polymer, by appropriately adjusting the constitutional unit of the (meth)acrylic polymer, the constitutional ratio, the selection and addition ratio of the crosslinking agent, etc. A pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) having more excellent heat resistance can be obtained.

  As the cross-linking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound, or the like may be used, and the use of the isocyanate compound is a preferred embodiment. These compounds may be used alone or in combination of two or more.

  Examples of the isocyanate compound (isocyanate-based crosslinking agent) include trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), aliphatic polyisocyanates such as dimer acid diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate. Alicyclic isocyanates such as (IPDI), 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, aromatic isocyanates such as xylylene diisocyanate (XDI), allophanate bond, biuret bond, and the above isocyanate compound. Examples thereof include modified polyisocyanate modified by isocyanurate bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond, oxadiazinetrione bond and the like. For example, as commercially available products, trade name Takenate 300S, Takenate 500, Takenate D165N, Takenate D178N (Takeda Pharmaceutical Co., Ltd.), Sumidule T80, Sumidule L, Death Module N3400 (above, Sumika Bayer Urethane Co., Ltd.) , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (above, manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like. These isocyanate compounds may be used alone or in combination of two or more, and it is also possible to use a bifunctional isocyanate compound and a trifunctional or higher functional isocyanate compound in combination. By using a cross-linking agent in combination, both tackiness and repulsion resistance (adhesion to curved surface) can be achieved, and a surface protective film with more excellent adhesion reliability can be obtained.

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

  Examples of the melamine-based resin include hexamethylol melamine. Examples of the aziridine derivative include trade names HDU, TAZM, and TAZO (these are manufactured by Mutual Yakuko Co., Ltd.).

  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 10 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer as a base polymer, To 8 parts by mass is more preferable, 0.5 to 5 parts by mass is more preferable, 1.0 to 2.5 parts by mass is most preferable. When the content is less than 0.01 parts by mass, the formation of crosslinks by the crosslinker becomes insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer becomes small, and sufficient heat resistance may not be obtained in some cases. It tends to cause glue residue. On the other hand, when the content exceeds 10 parts by mass, the cohesive force of the polymer is large, the fluidity is lowered, and the adherend (for example, a polarizing plate) is insufficiently wetted, so that the adherend and the adhesive are It tends to cause blisters generated between the layer (adhesive composition layer). Furthermore, when the amount of the cross-linking agent is large, the peeling charging property tends to be deteriorated.

  The pressure-sensitive adhesive composition may further contain a crosslinking catalyst in order to more effectively promote any of the crosslinking reactions described above. Examples of such a crosslinking catalyst include tin-based catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, tris(acetylacetonato)iron, tris(hexane-2,4-dionate)iron, tris(heptane-2,4-dionate). ) 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-1,3-dionato), tris(hexafluoro) Acetylacetonato) iron, tris(acetoacetate ethyl)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(propionyl methyl acetate) iron, tris(propionyl ethyl acetate) iron, tris(propionyl acetate-n-propyl) iron, tris(propionyl isopropyl acetate) 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, Iron-based catalysts such as tris(diethyl malonate) iron, trimethoxy iron, triethoxy iron, triisopropoxy iron, 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, as a base polymer, about 0.0001 to 1 part by mass is preferable relative to 100 parts by mass of the (meth)acrylic polymer, and 0.001 to 0. 5 parts by mass is more preferable. Within the above range, the crosslinking reaction rate is high when the pressure-sensitive adhesive layer is formed, and the pot life of the pressure-sensitive adhesive composition becomes long, which is a preferred embodiment.

  Further, the pressure-sensitive adhesive composition may contain an acrylic oligomer. The acrylic oligomer has a weight average molecular weight (Mw) of preferably 1,000 or more and less than 30,000, more preferably 1,500 or more and less than 20,000, further preferably 2,000 or more and less than 10,000. If the Mw is 30,000 or more, the tackiness (adhesion) is reduced. Further, when Mw is less than 1000, the molecular weight becomes low, which may cause a decrease in the adhesive strength of the adhesive sheet.

A (meth)acrylate monomer can be used for the acrylic oligomer, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, and (meth)acrylate. Butyl acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-Ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, (meth)acrylic acid Alkyl (meth)acrylates such as decyl, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate;
(Meth)acrylic acid aryl ester such as phenyl (meth)acrylate, benzyl (meth)acrylate;
Examples thereof include (meth)acrylic acid esters obtained from terpene compound derivative alcohols.
In addition, a (meth)acrylic monomer having an alicyclic structure can be used for the acrylic oligomer, and examples thereof include dicyclopentanyl methacrylate, dicyclopentanyl acrylate, dicyclopentanyloxyethyl methacrylate, and dicyclopentanyl. Oxyethyl acrylate, tricyclopentanyl methacrylate, tricyclopentanyl acrylate, 1-adamantyl methacrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, 2-methyl-2-adamantyl acrylate, 2-ethyl-2- Examples thereof include (meth)acrylic acid esters such as adamantyl methacrylate and 2-ethyl-2-adamantyl acrylate. Such (meth)acrylic monomers can be used alone or in combination of two or more kinds.

  Further, the acrylic oligomer is obtained by copolymerizing, in addition to the (meth)acrylic monomer component (unit), another monomer component (copolymerizable monomer) copolymerizable with the (meth)acrylic monomer. It is also possible.

  Furthermore, the pressure-sensitive adhesive composition may contain a compound that causes keto-enol tautomerism as a crosslinking retarder. For example, in a pressure-sensitive adhesive composition containing a crosslinking agent or a pressure-sensitive adhesive composition that can be used by blending a crosslinking agent, an embodiment containing a compound that produces the keto-enol tautomerism can be preferably adopted. As a result, it is possible to realize an effect of suppressing an excessive increase in viscosity and gelation of the pressure-sensitive adhesive composition after blending the crosslinking agent, and extending the pot life of the pressure-sensitive adhesive composition. 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 the form of an organic solvent solution or solvent-free.

  As the compound that causes the 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, 2,6-dimethylheptane- Β-diketones such as 3,5-dione; acetoacetic acid 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 acetates such as tert-butyl; isobutyryl acetates such as ethyl isobutyryl acetate, ethyl isobutyryl acetate, isopropyl isobutyryl acetate, tert-butyl isobutyryl acetate; malonates such as methyl malonate and ethyl malonate; Can be mentioned. Among them, preferred compounds include acetylacetone and acetoacetic acid esters. Such keto-enol tautomeric compounds may be used alone or in combination of two or more.

  The content of the compound that causes the keto-enol tautomerism can be, for example, 0.1 to 20 parts by mass with respect to 100 parts by mass of the (meth)acrylic polymer as a base polymer, and is usually Is appropriately 0.5 to 15 parts by mass (eg 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 in an unnecessarily large amount, it may remain in the pressure-sensitive adhesive layer and reduce the cohesive force.

  Further, the pressure-sensitive adhesive composition of the present invention may contain other known additives, for example, powders such as colorants and pigments, surfactants, plasticizers, tackifiers, low molecular weights. Polymers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, UV absorbers, polymerization inhibitors, silane coupling agents, inorganic or organic fillers, metal powders, particles, foils It can be appropriately added depending on the intended use of the product.

  The pressure-sensitive adhesive sheet of the present invention preferably has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition (formed by crosslinking the pressure-sensitive adhesive composition) on one side or both sides of the support film. The crosslinking of the pressure-sensitive adhesive composition is generally performed after the pressure-sensitive adhesive composition is applied, but it is also possible to transfer the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition after crosslinking to a support film or the like. Further, the method for forming the pressure-sensitive adhesive layer on the support film is not particularly limited, for example, the pressure-sensitive adhesive composition is applied to the support film, the polymerization solvent and the like are dried and removed to form the pressure-sensitive adhesive layer on the support film. It is produced by forming. Thereafter, curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. Further, when the pressure-sensitive adhesive composition is applied onto a supporting film to prepare a pressure-sensitive adhesive sheet, one or more solvents other than the polymerization solvent are newly added to the pressure-sensitive adhesive composition so that the pressure-sensitive adhesive composition can be uniformly applied onto the supporting film. May be added to.

<Supporting film>
As the support film, the resin material forming the support film can be used without particular limitation, for example, transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic, flexibility, It is preferable to use those having excellent characteristics such as dimensional stability. In particular, since the support film has flexibility, the pressure-sensitive adhesive composition can be applied by a roll coater or the like and can be wound into a roll, which is useful.

  Examples of the support film (base material) 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; polycarbonate-based polymers; A plastic film composed of a resin material containing an acrylic polymer such as methyl methacrylate; or the like as a main resin component (a main component among resin components, typically 50% by mass or more) is used as the support film. It can be preferably used. 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 type polymers; amide type polymers such as nylon 6, nylon 6,6 and aromatic polyamides. As still another example of the resin material, 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, a vinyl butyral polymer. , Arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers and the like. It may be a support film composed of a blend of two or more of the above-mentioned polymers.

  As the support film, a plastic film made of a transparent thermoplastic resin material can be preferably adopted. Among the plastic films, it is a more preferable embodiment to use a polyester film. Here, the polyester film is a film whose main resin component is a polymer material (polyester resin) having a main skeleton based on an ester bond such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate. Say. Such a polyester film has favorable properties as a support film for a pressure-sensitive adhesive sheet, such as excellent optical properties and dimensional stability, while having the property of being easily charged as it is.

  The resin material forming the support film may be mixed with various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a coloring agent (pigment, dye, etc.), if necessary. The first surface of the polyester film (the surface on the side where the antistatic layer is provided) is, for example, a known or commonly used product such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and undercoating agent coating. The surface treatment may be applied. Such a surface treatment can be, for example, a treatment for increasing the adhesion between the support film and the antistatic layer. A surface treatment in which a polar group such as a hydroxyl group is introduced on the surface of the support film can be preferably adopted. Further, the second surface of the support film (the surface on the side where the pressure-sensitive adhesive layer is formed) may be subjected to the same surface treatment as described above. Such surface treatment may be a treatment for enhancing the adhesion between the film and the pressure-sensitive adhesive layer (anchoring property of the pressure-sensitive adhesive layer).

  Further, the pressure-sensitive adhesive sheet of the present invention may have an antistatic layer on the support film, but when it has an antistatic function, a plastic film which has been subjected to antistatic treatment is further used as the support film. It is also possible to do so. The use of the support film is preferable because the pressure-sensitive adhesive sheet itself can be prevented from being charged when peeled. In addition, the support film is a plastic film, and by subjecting the plastic film to an antistatic treatment, it is possible to obtain an adhesive sheet which has a reduced charge of the adhesive sheet and an excellent antistatic ability to an adherend. The method for imparting the antistatic function is not particularly limited, and a conventionally known method can be used. For example, an antistatic resin or conductive polymer composed of an antistatic agent and a resin component, or a conductive substance can be used. Examples thereof include a method of applying a conductive resin contained therein, a method of vapor depositing or plating a conductive substance, and a method of kneading an antistatic agent and the like.

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

  As a method for forming the pressure-sensitive adhesive layer when manufacturing the pressure-sensitive adhesive sheet of the present invention, a known method used for manufacturing pressure-sensitive adhesive sheets can be used. Specific examples thereof 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 preferably 3 to 100 μm, more 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 a suitable balance between removability and adhesiveness (adhesion), which is preferable.

<Separator>
In the pressure-sensitive adhesive sheet (surface protective film) of the present invention, a 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.

  The separator is made of paper or plastic film, and the plastic film is preferably used because of its excellent surface smoothness. The film is not particularly limited as long as it is a film capable of protecting the pressure-sensitive adhesive layer, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer Examples thereof include a united 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 5 to 200 μm, preferably 10 to 100 μm. It is preferable for it to be in the above-mentioned range since the workability of attaching to the pressure-sensitive adhesive layer and the workability of peeling from the pressure-sensitive adhesive layer are excellent. In the separator, if necessary, a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, release and antifouling treatment with silica powder or the like, coating type, kneading type, vapor deposition type It is also possible to perform antistatic treatment such as.

In the pressure-sensitive adhesive sheet of the present invention, the pressure-sensitive adhesive layer (1 cm ² ) in the pressure-sensitive adhesive layer was attached to a TAC polarizing plate, and peeled in a shearing direction at a peeling rate of 0.06 m/min after being attached at 23° C. for 30 minutes. The shearing force at that time is preferably 8.5 N/cm ² or more, more preferably 10 to 50 N/cm ² , and further preferably 10 to 20 N/cm ² . If the shearing force is within the above range, the adherend can withstand the force in the shearing direction generated when the adherend is about to curl, and the adhesive sheet is prevented from slipping or shifting and curling the adherend. It is preferable because it can be suppressed.

<Antistatic layer (top coat layer)>
The pressure-sensitive adhesive sheet of the present invention has an antistatic layer on one surface of the support film on the side opposite to the pressure-sensitive adhesive layer, the antistatic layer is polyanilinesulfonic acid as a conductive polymer component, a polyester resin as a binder, and It is preferably formed from an antistatic agent composition containing an isocyanate crosslinking agent as a crosslinking agent. When the pressure-sensitive adhesive sheet has an antistatic layer (top coat layer), the antistatic property of the pressure-sensitive adhesive sheet is improved, which is a preferred embodiment.

<Conductive polymer>
The antistatic layer preferably contains polyanilinesulfonic acid as a conductive polymer component. By using the conductive polymer, the antistatic property based on the antistatic layer can be satisfied. Although the polyanilinesulfonic acid is "water-soluble", it can be fixed in the antistatic layer and the water resistance can be improved by using the isocyanate crosslinking agent described later. By using the water-soluble conductive polymer-containing aqueous solution, an antistatic layer having an excellent surface resistance over time can be obtained, which is a preferred embodiment. On the other hand, when the conductive polymer used in forming the antistatic layer is "water dispersible", when the antistatic layer is formed using the water dispersible conductive polymer-containing solution, aggregates are generated. It is not preferable because it becomes easy, the coating cannot be uniformly applied, and the surface resistance value over time tends to be significantly inferior.

  The content of the conductive polymer is preferably 10 to 200 parts by mass, more preferably 25 to 150 parts by mass, and still more preferably 100 parts by mass of the binder contained in the antistatic layer (top coat layer). Is 40 to 120 parts by mass. If the content of the conductive polymer is too low, the antistatic effect may be reduced, and if the content of the conductive polymer is too high, the adhesion to the support film of the antistatic layer may be reduced or the transparency may be low. It is not preferable because it may decrease.

The polyanilinesulfonic acid used as the conductive polymer component preferably has a polystyrene-equivalent weight average molecular weight (Mw) of 5×10 ⁵ or less, more preferably 3×10 ⁵ or less. The weight average molecular weight of these conductive polymers is usually preferably 1×10 ³ or more, more preferably 5×10 ³ or more.

As a method for forming the antistatic layer, a method of applying and drying (or curing) a coating material (antistatic agent composition) for forming the antistatic layer on the first surface of the support film can be adopted. As the conductive polymer component used in, it is preferable to contain polyaniline sulfonic acid, a polyester resin as a binder, and an isocyanate cross-linking agent as a cross-linking agent, wherein the essential components are dissolved in water (a conductive polymer aqueous solution). , Or simply referred to as an aqueous solution) can be preferably used. Such a conductive polymer aqueous solution is prepared, for example, by dissolving a conductive polymer having a hydrophilic functional group (which can be synthesized by a method such as copolymerizing a monomer having a hydrophilic functional group in the molecule) in water. can do. Examples of the hydrophilic functional group include a sulfo group, an amino group, an amide group, an imino group, a hydroxyl group, a mercapto group, a hydrazino group, a carboxyl group, a quaternary ammonium group, a sulfuric acid ester group (—O—SO ₃ H), and phosphorus. An acid ester group (for example, -O-PO(OH) ₂ ) and the like are exemplified. Such hydrophilic functional group may form a salt.

  Moreover, as a commercial item of the said polyaniline sulfonic acid aqueous solution, the brand name by the Mitsubishi Rayon Co., Ltd. "aqua-PASS" etc. are illustrated.

  The antistatic layer disclosed herein contains polyaniline sulfonic acid (polyaniline type) as an essential component as a conductive polymer component. However, for example, one or more other antistatic components (conductive polymer) are used. Other than organic conductive materials, inorganic conductive materials, antistatic agents, etc.) may be included together. As a preferred embodiment, the antistatic layer does not substantially contain an antistatic component other than the conductive polymer, that is, the antistatic component contained in the antistatic layer is substantially only a conductive polymer. Can be more preferably carried out.

  Examples of the organic conductive substance include a cation type antistatic agent having a cationic functional group such as a quaternary ammonium salt, a pyridinium salt, a primary amino group, a secondary amino group and a tertiary amino group; a sulfonate or a sulfate ester. Anionic antistatic agents having anionic functional groups such as salts, phosphonates and phosphate salts; zwitterionic antistatic agents such as alkylbetaine and its derivatives, imidazoline and its derivatives, alanine and its derivatives; amino alcohols And its derivatives, glycerin and its derivatives, polyethylene glycol and its derivatives, and other nonionic antistatic agents; the above-mentioned cationic, anionic, and zwitterionic ion-conductive groups (for example, quaternary ammonium salt group)-containing monomers are polymerized. Alternatively, an ion conductive polymer obtained by copolymerization; a conductive polymer such as polythiophene, polyaniline, polypyrrole, polyethyleneimine, and an allylamine-based polymer; Such antistatic agents may be used alone or in combination of two or more.

  As the inorganic conductive material, tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, Examples include copper iodide, ITO (indium oxide/tin oxide), ATO (antimony oxide/tin oxide), and the like. Such inorganic conductive materials may be used alone or in combination of two or more.

  As the antistatic agent, a cationic type antistatic agent, an anion type antistatic agent, a zwitterionic type antistatic agent, a nonionic type antistatic agent, a single type having anionic conductive group of the cationic type, anionic type and zwitterionic type. Examples thereof include an ion conductive polymer obtained by polymerizing or copolymerizing a monomer.

<Binder>
The antistatic layer preferably contains a polyester resin as a binder. The polyester resin is preferably a resin material containing polyester as a main component (typically more than 50% by mass, preferably 75% by mass or more, for example, 90% by mass or more). The polyester typically includes polyvalent carboxylic acids having two or more carboxyl groups in one molecule (typically dicarboxylic acids) and derivatives thereof (anhydrides, esterified products, halogens of the polyvalent carboxylic acids). Selected from polyhydric alcohols (typically diols) having at least two hydroxyl groups in one molecule. It is preferable to have a structure in which one or two or more kinds of compounds (polyhydric alcohol component) are condensed.

  Examples of compounds that can be used as the polycarboxylic acid component include oxalic acid, malonic acid, difluoromalonic acid, alkylmalonic acid, succinic acid, tetrafluorosuccinic acid, alkylsuccinic acid, (±)-malic acid, and meso. -Tartaric acid, itaconic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, acetylenedicarboxylic acid, glutaric acid, hexafluoroglutaric acid, methylglutaric acid, glutaconic acid, adipic acid, dithioadipic acid, methyladipic acid, dimethyl Adipic acid, tetramethyladipic acid, methyleneadipic acid, muconic acid, galactaric acid, pimelic acid, suberic acid, perfluorosuberic acid, 3,3,6,6-tetramethylsuberic acid, azelaic acid, sebacic acid, perfluoro Aliphatic dicarboxylic acids such as sebacic acid, brassic acid, dodecyldicarboxylic acid, tridecyldicarboxylic acid, tetradecyldicarboxylic acid; cycloalkyldicarboxylic acid (for example, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid), Alicyclic dicarboxylic acids such as 1,4-(2-norbornene)dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid (hymic acid), adamantanedicarboxylic acid, spiroheptanedicarboxylic acid; phthalic acid, isophthalic acid, dithio Isophthalic acid, methylisophthalic acid, dimethylisophthalic acid, chloroisophthalic acid, dichloroisophthalic acid, terephthalic acid, methylterephthalic acid, dimethylterephthalic acid, chloroterephthalic acid, bromoterephthalic acid, naphthalenedicarboxylic acid, oxofluorangecarboxylic acid, anthracenedicarboxylic acid , Biphenyldicarboxylic acid, biphenylenedicarboxylic acid, dimethylbiphenylenedicarboxylic acid, 4,4"-p-terephenylenedicarboxylic acid, 4,4"-p-quarrelphenyldicarboxylic acid, bibenzyldicarboxylic acid, azobenzenedicarboxylic acid, homophthalic acid , Phenylenediacetic acid, phenylenedipropionic acid, naphthalenedicarboxylic acid, naphthalenedipropionic acid, biphenyldiacetic acid, biphenyldipropionic acid, 3,3'-[4,4'-(methylenedi-p-biphenylene)dipropionic acid, Aromatic dicarboxylic acids such as 4,4′-bibenzyldiacetic acid, 3,3′(4,4′-bibenzyl)dipropionic acid, and oxydi-p-phenylenediacetic acid; acids of any of the above polyvalent carboxylic acids Anhydride; S of any of the above-mentioned polycarboxylic acids Tell (eg alkyl ester. It can be a monoester, a diester and the like. ); an acid halide (for example, dicarboxylic acid chloride) corresponding to any of the above-described polycarboxylic acids; and the like.

  Suitable examples of compounds that can be adopted as the polyvalent carboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and naphthalene dicarboxylic acid and acid anhydrides thereof; adipic acid, sebacic acid, azelaic acid, succinic acid, Aliphatic dicarboxylic acids such as fumaric acid, maleic acid, hymic acid, 1,4-cyclohexanedicarboxylic acid and their acid anhydrides; and lower alkyl esters of the dicarboxylic acids (for example, with monoalcohols having 1 to 3 carbon atoms) Ester) and the like.

  On the other hand, examples of compounds that can be adopted as the polyhydric alcohol component include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and 1,4-butanediol. , Neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol, diethylene glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 2-methyl- Diols such as 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, xylylene glycol, hydrogenated bisphenol A and bisphenol A Is mentioned. Other examples include alkylene oxide adducts of these compounds (eg, ethylene oxide adducts, propylene oxide adducts, etc.).

The molecular weight of the polyester resin is, for example, about 5×10 ^{3 to} 1.5×10 ⁵ (preferably 1×10 5) as a weight average molecular weight (Mw) in terms of standard polystyrene measured by gel permeation chromatography (GPC). ^{4 to} 6×10 ⁴ )). The glass transition temperature (Tg) of the polyester resin may be, for example, 0 to 120°C (preferably 10 to 80°C).

  As the polyester resin, commercially available Toyobo Co., Ltd. trade name “Bironard MD-1480” and the like can be used.

  The antistatic layer (top coat layer) is a resin other than a polyester resin as a binder as long as the performance (for example, performance such as antistatic property) of the pressure-sensitive adhesive sheet (surface protection film) disclosed herein is not significantly impaired. (For example, one or more resins selected from acrylic resin, acrylic-urethane resin, acrylic-styrene resin, acrylic-silicone resin, silicone resin, polysilazane resin, polyurethane resin, fluororesin, polyolefin resin, etc.) It may further contain. In a preferred embodiment of the technology disclosed herein, the binder of the antistatic layer is substantially made of polyester resin. For example, an antistatic layer in which the proportion of polyester resin in the binder is 98 to 100 mass% is preferable. The proportion of the binder in the entire antistatic layer can be, for example, 50 to 95% by mass, and usually 60 to 90% by mass is suitable.

<Lubricant>
The antistatic layer (top coat layer) preferably uses a fatty acid amide as a lubricant. By using a fatty acid amide as a lubricant, further release treatment is performed on the surface of the antistatic layer (for example, a treatment in which a known release treatment agent such as a silicone release agent or a long-chain alkyl release agent is applied and dried). Even in the case where it is not applied, an antistatic layer (top coat layer) having both sufficient slipperiness and print adhesion can be obtained, so that it may be a preferable embodiment. As described above, the embodiment in which the surface of the antistatic layer is not further subjected to the peeling treatment may prevent the whitening (for example, the whitening due to the storage under the heating and humidifying conditions) caused by the peeling treatment agent. It is preferable in terms. It is also advantageous in terms of solvent resistance.

  Specific examples of the fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, oleic acid amide, erucic acid amide, N-oleylpaltimic acid amide, and N-stearyl stearic acid. Amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, methylol stearic acid amide, methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid Amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N ′-Distearyl sebacic acid amide, ethylenebisoleic acid amide, ethylenebiserucic acid amide, hexamethylenebisoleic acid amide, N,N′-dioleyl adipic acid amide, N,N′-dioleyl sebacic acid amide, m -Xylylenebisstearic acid amide, m-xylylenebishydroxystearic acid amide, N,N'-stearylisophthalic acid amide and the like can be mentioned. These lubricants may be used alone or in combination of two or more.

  The proportion of the lubricant in the entire antistatic layer can be 1 to 50% by mass, and usually 5 to 40% by mass is suitable. If the content ratio of the lubricant is too small, the slipperiness tends to decrease. If the content of the lubricant is too large, the print adhesion may be reduced.

  The technology disclosed herein can be carried out in a mode in which the antistatic layer (top coat layer) contains other lubricant in addition to the fatty acid amide, as long as the application effect is not significantly impaired. Examples of such other lubricants include various waxes such as petroleum wax (paraffin wax and the like), mineral wax (montan wax and the like), higher fatty acid (cerotic acid and the like), and neutral fat (palmitic acid triglyceride and the like). Be done. Alternatively, in addition to the wax, a general silicone lubricant, a fluorine lubricant or the like may be supplementarily contained. The technique disclosed herein can be preferably carried out in a mode in which the silicone-based lubricant, the fluorine-based lubricant and the like are not substantially contained. However, as long as the application effect of the technology disclosed herein is not significantly impaired, the inclusion of a silicone compound used for a purpose other than the lubricant (for example, as an antifoaming agent for the coating material for forming an antistatic layer described later). Does not exclude

<Crosslinking agent>
The antistatic layer preferably contains an isocyanate crosslinking agent as a crosslinking agent. By using the isocyanate cross-linking agent, water-soluble polyaniline sulfonic acid, which is an essential component when forming the antistatic layer, can be fixed in the binder, has excellent water resistance, and further improves print adhesion. The effect can be realized.

  It is a preferred embodiment that a blocked isocyanate-based crosslinking agent that is stable in an aqueous solution is used as the isocyanate-based crosslinking agent. Specific examples of the blocked isocyanate-based cross-linking agent include isocyanate-based cross-linking agents that can be used in the preparation of general pressure-sensitive adhesive layers and antistatic layers (top coat layers) (for example, used in the pressure-sensitive adhesive layer described above. Isocyanate compounds (isocyanate-based cross-linking agents) that are alcohols, phenols, thiophenols, amines, imides, oximes, lactams, active methylene compounds, mercaptans, imines, ureas, diaryl compounds , And those blocked with sodium bisulfite or the like can be used.

  The antistatic layer in the technology disclosed herein may include an antistatic component, an antioxidant, a colorant (a pigment, a dye, etc.), a fluidity modifier (a thixotropy agent, a thickener, etc.), a film-forming agent, if necessary. Additives such as auxiliaries, surfactants (such as antifoaming agents) and preservatives may be contained.

<Formation of antistatic layer>
The antistatic layer (top coat layer) is a liquid composition (for forming an antistatic layer) in which the essential components such as the conductive polymer component and additives used as necessary are dissolved in a suitable solvent (such as water). It can be suitably formed by a method including applying a coating material of (1) to a support film. For example, a method in which the coating material is applied to the first surface of the support film, dried, and if necessary, a curing treatment (heat treatment, ultraviolet treatment, etc.) can be preferably adopted. The NV (nonvolatile content) of the coating material can be, for example, 5% by mass or less (typically 0.05 to 5% by mass), and usually 1% by mass or less (typically 0.10 to 10% by mass). 1% by mass) is suitable. When forming an antistatic layer having a small thickness, the NV of the coating material is preferably 0.05 to 0.50 mass% (for example, 0.10 to 0.40 mass%). By using the low NV coating material as described above, a more uniform antistatic layer can be formed.

  As the solvent constituting the coating material for forming the antistatic layer, those capable of stably dissolving the components for forming the antistatic layer are preferable. Such a solvent may be an organic solvent, water, or a mixed solvent thereof. Examples of the organic solvent include esters such as ethyl acetate; ketones such as methyl ethyl ketone, acetone and cyclohexanone; cyclic ethers such as tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic compounds such as n-hexane and cyclohexane. Hydrocarbons; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, cyclohexanol; alkylene glycol monoalkyl ethers (for example, ethylene glycol monomethyl ether) , Ethylene glycol monoethyl ether), glycol ethers such as dialkylene glycol monoalkyl ether; and the like. In a preferred aspect, the solvent of the coating material is water or a mixed solvent containing water as a main component (for example, a mixed solvent of water and ethanol).

<Properties of antistatic layer>
The thickness of the antistatic layer is typically 3 to 500 nm, preferably 3 to 100 nm, more preferably 3 to 60 nm). If the thickness of the antistatic layer is too small, it becomes difficult to form the antistatic layer uniformly (for example, in the thickness of the antistatic layer, the thickness varies depending on the location). The appearance of the film) may easily become uneven. On the other hand, if it is too thick, the characteristics of the support film (optical characteristics, dimensional stability, etc.) may be affected.

In a preferred embodiment of the pressure-sensitive adhesive sheet (surface protection film) disclosed herein, the surface resistance value (Ω/□) measured on the surface of the antistatic layer is preferably less than 1.0×10 ¹¹ . , More preferably less than 5.0×10 ¹⁰ and even more preferably less than 2.0×10 ¹⁰ . The pressure-sensitive adhesive sheet having a surface resistance value within the above range can be suitably used as a pressure-sensitive adhesive sheet used, for example, in the processing or transportation of articles such as liquid crystal cells and semiconductor devices that are sensitive to static electricity. The surface resistance value can be calculated from the surface resistance value measured in an atmosphere of 23° C. and 50% RH using a commercially available insulation resistance measuring device.

  The pressure-sensitive adhesive sheet (surface protective film) disclosed herein has a property that the back surface (surface of the antistatic layer) can be easily printed with a water-based ink or an oil-based ink (for example, using an oil-based marking pen). preferable. In such a pressure-sensitive adhesive sheet, the identification number and the like of the adherend to be protected are written on the front pressure-sensitive adhesive sheet in the process of processing or transporting the adherend (for example, an optical component) performed with the pressure-sensitive adhesive sheet attached. It is suitable for displaying. Therefore, it is preferable that the pressure-sensitive adhesive sheet has excellent printability. For example, it is preferable that the solvent is alcoholic and has high printability with respect to an oil-based ink of a type including a pigment. Further, it is preferable that the printed ink is difficult to be removed due to rubbing or transfer (that is, the printing adhesion is excellent). The pressure-sensitive adhesive sheet disclosed herein also preferably has solvent resistance to the extent that when the print is corrected or erased, the print is wiped off with alcohol (for example, ethyl alcohol) without causing a noticeable change in appearance. ..

  The pressure-sensitive adhesive sheet (surface protection film) disclosed herein may be embodied in a mode including other layers in addition to the support film (base material), the pressure-sensitive adhesive layer, and the antistatic layer. Examples of the arrangement of such "another layer" include between the first surface (back surface) of the support film and the antistatic layer, between the second surface (front surface) of the support film and the adhesive layer, and the like. The layer arranged between the back surface of the support film and the antistatic layer can be, for example, a layer containing an antistatic component (the antistatic layer described above). The layer arranged between the front surface of the support film and the pressure-sensitive adhesive layer may be, for example, an undercoat layer (anchor layer) that enhances the anchoring property of the pressure-sensitive adhesive layer to the second surface, an antistatic layer, or the like. The pressure-sensitive adhesive sheet may have a structure in which an antistatic layer is disposed on the front surface of the support film, an anchor layer is disposed on the antistatic layer, and a pressure-sensitive adhesive layer is disposed thereon.

  The optical member of the present invention is preferably protected by the pressure-sensitive adhesive sheet. Since the pressure-sensitive adhesive sheet has excellent shearing force, curling of the adherend (optical member) to which the pressure-sensitive adhesive sheet is attached can be suppressed, and the handleability is excellent, which is useful.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described, but the present invention is not limited thereto. In addition, about the mixing|blending content in an Example etc., and characteristic evaluation, it measured as follows. Further, Table 1 shows the physical property values of the (meth)acrylic polymer used in the pressure-sensitive adhesive composition and the mixing ratio of the pressure-sensitive adhesive composition, and Table 2 shows the content of the antistatic layer and the like. Shows the evaluation results of the characteristics of the adhesive sheet.

<Evaluation>
The specific measurement/evaluation methods are described below.

<Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)>
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the (meth)acryl-based polymer and the like used in the present invention were measured using a GPC device (HLC-8220GPC) manufactured by Tosoh Corporation. The measurement conditions are as follows.

Sample concentration: 0.2 mass% (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6 ml/min
Measurement temperature: 40°C
column:
Sample column; TSKguard super column HZ-H (1 line) + TSK gel Super HZM-H (2 lines)
Reference column; TSKgel Super H-RC (1)
Detector: Differential refractometer (RI)
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were calculated in terms of polystyrene.

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

Formula: 1/(Tg+273)=Σ[Wn/(Tgn+273)]
[In the formula, Tg (°C) is the glass transition temperature of the copolymer, Wn (-) is the mass fraction of each monomer, Tgn (°C) is the glass transition temperature of the homopolymer of each monomer, and n is the type of each monomer. Represents. ]
Literature value:
2-Ethylhexyl acrylate (2EHA): -70°C
n-Butyl acrylate (BA): -55°C
Acrylic acid (AA): 106°C
2-hydroxyethyl acrylate (HEA): -15°C
4-hydroxybutyl acrylate (HBA): -32°C

  As literature values, “Synthesis and design of acrylic resin and development of new applications” (published by the Central Management Development Center) and “Polymer Handbook” (John Wiley & Sons) were referred to.

<Measurement of shearing force>
After cutting the pressure-sensitive adhesive sheet into a size of 10 mm in width and 100 mm in length and peeling off the separator, the TAC polarizing plate (Nitto Denko Corp.) was used so that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet had an adhesive (adhesion) area of 1 cm ^2. Manufactured by SEG1423DU polarizing plate, width: 25 mm, length: 100 mm), and allowed to stand at room temperature (23° C.×50% RH) for 30 minutes, then peeled at a peeling speed of 0.06 m/min and pulled in the shear direction. The maximum load (N/cm ² ) at that time was defined as the shearing force.

The shearing force is preferably 8.5 N/cm ² or more, more preferably 10 to 50 N/cm ² , and even more preferably 10 to 20 N/cm ² . If the shearing force is within the above range, the adherend can withstand the force in the shearing direction generated when the adherend is about to curl, and the adhesive sheet is prevented from slipping or shifting and curling the adherend. It is preferable because it can be suppressed.

<Measurement of surface resistance>
In an atmosphere of a temperature of 23° C. and a humidity of 50% RH, a resistivity meter (HIRESTA UP MCP-HT450 type manufactured by Mitsubishi Chemical Analytical Co., Ltd.) was used for measurement according to JIS-K-6911.

The surface resistance value (Ω/□) of the surface of the antistatic layer in the present invention is the initial value (before aging treatment), and room temperature (23° C.×50% RH)×1 week (7 days). After the treatment), both are preferably less than 1.0×10 ¹¹ , more preferably less than 5.0×10 ¹⁰ , and even more preferably less than 2.0×10 ¹⁰ . The pressure-sensitive adhesive sheet having a surface resistance value within the above range (surface protection film) is preferably used as a pressure-sensitive adhesive sheet used in the process of processing or transporting articles such as liquid crystal cells and semiconductor devices that are sensitive to static electricity. obtain.

<Measurement of peeling electrification voltage>
TAC that is obtained by cutting the adhesive sheet 2 into a size of 70 mm in width and 130 mm in length, peeling off the separator, and then pasting it on an acrylic plate 4 (thickness: 2 mm, width: 70 mm, length: 100 mm) that has been precharged. Polarizing plate 3 (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) was pressure-bonded to the surface (TAC surface) with a hand roller so that one end protrudes by 30 mm.

  After leaving at 23° C.×50% RH for 1 day, the sample was set at a predetermined position as shown in FIG. One end protruding 30 mm was fixed to an automatic winder, and peeling was performed at a peeling angle of 150° and a peeling speed of 30 m/min (high-speed peeling). The potential (peeling electrification voltage: absolute value, kV) on the surface of the polarizing plate generated at this time was measured by a potential measuring device 1 (KSD-0103, manufactured by Kasuga Denki KK) fixed at the central position of the polarizing plate. The measurement was performed under the environment of 23° C.×50% RH.

  At the peeling angle of 150° and the peeling speed of 30 m/min after the adhesive surface of the adhesive layer used for the adhesive sheet was stuck (left) for 1 day at 23° C.×50% RH with respect to the TAC surface (polarizing plate surface). The potential (peeling electrification voltage: kV, absolute value) on the surface of the polarizing plate generated when peeling (high-speed peeling) is preferably 1.0 kV or less, more preferably 0.8 kV or less, still more preferably 0.6 kV or less. When the peeling electrification voltage exceeds 1.0 kV, for example, the liquid crystal driver may be damaged, which is not preferable.

<Evaluation of printability (print adhesion)>
After printing on the surface of the antistatic layer using an X stamper manufactured by Shachihata under a measurement environment of 23° C.×50% RH, a Nichiban Cellotape (registered trademark) is pasted on the print, Next, peeling is performed under the conditions of a peeling speed of 30 m/min and a peeling angle of 180°. After that, visually observing the surface after peeling, when 50% or more of the printing area was peeled off (poor printability), and when 50% or more of the printing area remained without peeling (good printability) ) Was evaluated.

<Preparation method>
Hereinafter, a specific method for synthesizing a (meth)acrylic polymer and a method for preparing a pressure-sensitive adhesive composition will be described.

<Preparation of adhesive composition 1>
95 parts by mass of 2-ethylhexyl acrylate (2EHA), 4.99 parts by mass of 2-hydroxyethyl acrylate (HEA), acrylic acid (AA) was added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser. ) 0.01 parts by mass, 0.22 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 to prepare a flask. A (meth)acrylic polymer solution (40% by mass) was prepared by carrying out a polymerization reaction for 6 hours while maintaining the liquid temperature near 65°C. The (meth)acrylic polymer had a weight average molecular weight (Mw) of 520,000 and a glass transition temperature (Tg) of -68°C.

  The (meth)acrylic polymer solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass of this solution (100 parts by mass of solid content) was added as a cross-linking agent to the hexavalent compound of the aliphatic isocyanate compound. 2.5 parts by mass of isocyanurate of methylene diisocyanate (Coronate HX manufactured by Nippon Polyurethane Industry Co., Ltd., solid content: 2.5 parts by mass), 3 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) as a crosslinking catalyst ( Solid content (0.03 parts by mass) was added and mixed and stirred to prepare an adhesive composition 1 (solution).

<Preparation of Aqueous Solution for Antistatic Layer (Back Treatment A)>
Polyester resin Vylonal MD-1480 (25% aqueous solution, manufactured by Toyobo Co., Ltd.) as a binder, polyaniline sulfonic acid (aquapass, weight average molecular weight 40,000, manufactured by Mitsubishi Rayon Co., Ltd.) as a conductive polymer, and hexamethylene blocked with diisopropylamine as a crosslinking agent. Isocyanurate of diisocyanate, as a lubricant, oleic acid amide in a mixed solvent of water/ethanol (1/3), 100 parts by mass of binder in solid content, 75 parts by mass of conductive polymer in solid content, and solid crosslinking agent. 10 parts by mass of the lubricant and 30 parts by mass of the lubricant were added, and the mixture was stirred for about 20 minutes and sufficiently mixed. Thus, an aqueous solution for an antistatic layer having an NV of about 0.4% by mass was prepared.

<Preparation of Aqueous Solution for Antistatic Layer (Back Treatment B)>
Polyester resin Bayronal MD-1480 (25% aqueous solution, manufactured by Toyobo Co., Ltd.) as a binder, polyanilinesulfonic acid (aquapass, weight average molecular weight 40,000, manufactured by Mitsubishi Rayon Co., Ltd.) as a conductive polymer, and hexamethylene blocked with diisopropylamine as a cross-linking agent. The isocyanurate of diisocyanate is mixed with water/ethanol (1/3) in a mixed amount of 100 parts by mass of binder, 75 parts by mass of conductive polymer, and 10 parts by mass of crosslinking agent. Add and stir for about 20 minutes to mix well. Thus, an aqueous solution for an antistatic layer having an NV of about 0.4% by mass was prepared.

<Supporting film 1>
A transparent polyethylene terephthalate (PET) film (polyester film) having a thickness of 38 μm, a width of 30 cm and a length of 40 cm was used as the support film 1.

<Production of Support Film 2 with Antistatic Layer>
A transparent polyethylene terephthalate (PET) film (polyester film) having a thickness of 38 μm, a width of 30 cm, and a length of 40 cm, which is corona-treated on one surface (first surface) of the support film 1, and the antistatic layer ( An aqueous solution of either the backside treating agent A or B) was applied so that the thickness after drying would be 30 nm. The coated material was heated at 130° C. for 1 minute and dried to prepare a support film 2 with an antistatic layer having an antistatic layer on the first surface of the PET film.

<Example 1>
<Preparation of adhesive sheet>
The pressure-sensitive adhesive composition 1 (solution) was applied to one surface of the support film 1 and heated at 130° C. for 1 minute to form a pressure-sensitive adhesive layer having a thickness of 15 μm. Then, a silicone-treated surface of a polyethylene terephthalate film (thickness: 25 μm), which is a separator whose one surface was treated with silicone, was attached to the surface of the pressure-sensitive adhesive layer to prepare a pressure-sensitive adhesive sheet (surface protective film).

<Examples 2-7 and Comparative Examples 1-2>
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet were produced in the same manner as in Example 1 based on the blending ratios in Table 1 and Table 2. In addition, the compounding quantity in Table 1 showed solid content. In Examples 3 and 4, the support film 2 with an antistatic layer was used instead of the support film 1 used in Example 1.

  According to the above evaluation method, the shearing force of the pressure-sensitive adhesive sheet produced, and peeling electrification voltage, in the antistatic layer, the presence or absence of aggregates in the solution at the time of producing the antistatic layer, initial (before aging treatment), and aging The surface resistance and the print adhesion were evaluated, and the evaluation results are shown in Tables 2 and 3.

The abbreviations in Table 1 and Table 2 are explained below.
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate AA: acrylic acid (carboxyl group-containing (meth) acrylic monomer)
HEA: 2-hydroxyethyl acrylate (hydroxyl group-containing (meth)acrylic monomer)
HBA: 4-hydroxybutyl acrylate (hydroxyl group-containing (meth)acrylic monomer)
C/HX: Nippon Polyurethane Company, trade name "Coronate HX", aliphatic isocyanate compound, hexamethylene diisocyanate isocyanurate (crosslinking agent)
HDPTFI: 1-hexadecylpyridinium bis(trifluoromethanesulfonyl)imide (melting point: 34° C.) (onium salt, carbon number of alkyl group of onium cation constituting onium salt: 16)
HDMITFI: 1-hexadecyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (melting point: 42°C) (onium salt, carbon number of alkyl group of onium cation constituting onium salt: 16)
MTOATF: Methyltrioctylammonium trifluoromethanesulfonate (melting point: 55° C.) (onium salt, carbon number of alkyl group of onium cation constituting onium salt: 8)
HDMIHP: 1-hexadecyl-3-methylimidazolium hexafluorophosphate (melting point: 125°C) (onium salt, carbon number of alkyl group of onium cation constituting onium salt: 16)
TDDAB: tetradodecyl ammonium bromide (melting point: 90° C.) (onium salt, carbon number of alkyl group of onium cation constituting onium salt: 12)
HMITF: 1-hexyl-3-methylimidazolium trifluoromethanesulfonate (melting point: 23° C.) (onium salt, carbon number of alkyl group of onium cation constituting onium salt: 6)
AO compound: a compound having an alkylene oxide group 25R-1: manufactured by ADEKA, trade name "ADEKA PLURONIC 25R-1" (number average molecular weight 2800, ethylene oxide group content: 10% by mass)
KF355A: manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KF-355A" (organopolysiloxane having alkylene oxide group (HLB value 12))

  From the results of Table 3 above, it was confirmed that the shearing force and the antistatic property were excellent in all of the examples. It was also confirmed that Examples 3 and 4 having the antistatic layer were further excellent in surface resistance and print adhesion.

  On the other hand, in the comparative example, since the onium salt containing no onium cation having at least one alkyl group having 8 or more carbon atoms was used, the shearing force was low, and it was confirmed to be inferior to the examples. ..

1 Potential measuring device 2 Adhesive sheet 3 Polarizing plate 4 Acrylic plate 5 Fixing stand

Claims (7)

It contains an onium salt having a melting point of 150° C. or lower, a cross-linking agent, and a (meth)acrylic polymer having a glass transition temperature of 0° C. or lower as a base polymer,
0.005 to 0.09 mass% of a carboxyl group-containing (meth)acrylic monomer is contained with respect to the total amount of monomer components constituting the (meth)acrylic polymer,
The onium salt is at least one selected from the group consisting of nitrogen-containing onium salts, sulfur-containing onium salts, and phosphorus-containing onium salts,
The onium salt contains an onium cation having at least one alkyl group having 8 or more carbon atoms,
Furthermore, a pressure-sensitive adhesive composition comprising a compound having an alkylene oxide group having a number average molecular weight of 10,000 or less. The pressure-sensitive adhesive composition according to claim 1, wherein the compound having an alkylene oxide group is an organopolysiloxane having an alkylene oxide group. The pressure-sensitive adhesive composition according to claim 1 or 2 , wherein the (meth)acrylic polymer having a glass transition temperature of 0°C or lower is a (meth)acrylic polymer having a hydroxyl group and a carboxyl group. object. An adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 3, and a one side or pressure-sensitive adhesive sheet having both surfaces of the support film,
A shearing force of 1 cm ² of the pressure-sensitive adhesive layer stuck to a TAC polarizing plate and peeling in the shearing direction at a peeling speed of 0.06 m/min after sticking at 23° C. for 30 minutes was 8.5 N/cm ² The above is the pressure-sensitive adhesive sheet. The pressure-sensitive adhesive layer has an antistatic layer on one side of the support film on the opposite side,
The antistatic layer, a conductive polymer component as polyaniline sulfonic acid, a polyester resin as a binder, and, to claim 4, characterized in that it is formed from the antistatic composition containing the isocyanate crosslinking agent as crosslinking agent The adhesive sheet described. The pressure-sensitive adhesive sheet according to claim 5 , wherein the antistatic agent composition further contains a fatty acid amide as a lubricant. An optical member protected by the pressure-sensitive adhesive sheet according to claim 4 .