JP6636556B2 - Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, and optical member - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and an optical member. In particular, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition is suitable for application to a plastic product or the like in which static electricity is likely to be generated, and particularly, an optical member (for example, a polarizing plate used for a liquid crystal display or the like, It is useful as a surface protection film used for the purpose of protecting the surface such as a wave plate, a retardation plate, an optical compensation film, a reflection sheet, and a brightness enhancement film).

  The surface protection film is generally bonded to a protected object via an adhesive applied to the protective film side, and is used for the purpose of preventing scratches and stains generated during processing and transport of the protected object. For example, a panel of a liquid crystal display is formed by attaching an optical member such as a polarizing plate or a wave plate to a liquid crystal cell via an adhesive. These optical members to be bonded to the liquid crystal cell have a protective film bonded thereto via an adhesive for the purpose of preventing scratches and dirt.

  Then, when the optical member is bonded to the liquid crystal cell and the protective film becomes unnecessary, the protective film is peeled off and removed. Generally, since the protective film and the optical member are made of a plastic material, they have high electrical insulation properties and generate static electricity when they are rubbed or peeled off. Therefore, static electricity is also generated when the protective film is peeled off from an optical member such as a polarizing plate. When a voltage is applied to the liquid crystal while static electricity remains, the alignment of liquid crystal molecules is lost or the panel is damaged. Therefore, in order to prevent such problems, the surface protective film is subjected to various antistatic treatments.

  For example, a method is disclosed in which one or more surfactants are added to the pressure-sensitive adhesive layer, and the surfactant is transferred from the pressure-sensitive adhesive layer to an adherend to prevent static electricity (for example, see Patent Document 1). . However, in the present invention, the surfactant easily bleeds on the surface of the pressure-sensitive adhesive layer, and when applied to a protective film, there is a concern about contamination of the adherend. Therefore, when a pressure-sensitive adhesive layer to which a low molecular surfactant is added is applied to a protective film for an optical member, it is difficult to develop sufficient antistatic characteristics without impairing the optical characteristics of the optical member.

  Further, a method has been disclosed in which an antistatic agent comprising a polyether polyol and an alkali metal salt is added to an acrylic adhesive to suppress the bleeding of the antistatic agent on the surface of the adhesive (for example, see Patent Document 2). . However, even in this method, bleeding of the antistatic agent is inevitable, and as a result, when applied to a surface protection film, if the treatment is performed with time or at a high temperature, contamination to the adherend due to the bleed phenomenon occurs. May occur.

  When a surface protective film is attached to an adherend (such as a polarizing plate), unnecessary or unintended curl (curl from curl) occurs on the adherend (such as a polarizer) to which the surface protective film is attached. This refers to a phenomenon in which, for example, a flat plate is curled so as to entirely warp on one of the surfaces, or a flat plate is warped so as to be entirely wavy. Adjustability is required. If unnecessary curl or unintended curl occurs, the handleability is poor. For example, when an adherend such as a polarizing plate is attached to a liquid crystal cell, a problem such as air bubble entrapment may occur.

  In addition, when curl occurs on the flat adherend, a force accompanying the curl acts in the shear direction on the adhesive layer of the surface protection film bonded to the adherend, and this force causes the adherence. Since slippage and displacement occur gradually between the body and the pressure-sensitive adhesive layer, an improvement in the shearing force during low-speed peeling is required.

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

  Accordingly, the present invention has been made in view of the above circumstances, and as a result of intensive studies, it has been made an object to provide a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and an optical member capable of achieving a shear force at the time of low-speed peeling and an antistatic property of peeling. And

  That is, the pressure-sensitive adhesive composition of the present invention contains, as a monomer component, 40% by mass or more of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, 0.5 to 20% by mass of a nitrogen-containing monomer, and , A (meth) acrylic polymer containing 0.5 to 40% by mass of an alkylene oxide group-containing monomer, and an organic salt and / or an alkali metal salt having a melting point of 150 ° C. or less.

  In the pressure-sensitive adhesive composition of the present invention, the organic salt having a melting point of 150 ° C. or less is preferably at least one selected from the group consisting of a nitrogen-containing onium salt, a sulfur-containing onium salt, and a phosphorus-containing onium salt.

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer preferably contains a carboxyl group-containing monomer as a monomer component in an amount of 0.01% by mass or more and less than 1% by mass.

  It is preferable that the pressure-sensitive adhesive composition of the present invention further contains an alkylene oxide group-containing compound containing no organopolysiloxane having a number average molecular weight of 10,000 or less.

  The pressure-sensitive adhesive composition of the present invention is preferably formed by forming a pressure-sensitive adhesive layer obtained by crosslinking the pressure-sensitive adhesive composition on one surface or both surfaces of a support.

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

  The pressure-sensitive adhesive composition of the present invention is obtained by containing a (meth) acrylic polymer containing a specific monomer in a specific ratio, an organic salt having a melting point of 150 ° C. or lower, and / or an alkali metal salt. Since the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) is excellent in shearing force at the time of low-speed peeling, it can suppress unnecessary curl and unintended curl in the adherend when bonded to the adherend, Furthermore, since it is excellent in anti-peeling antistatic property, it is particularly useful for surface protection of optical members.

It is explanatory drawing which shows the measuring method of a peeling charge voltage.

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

  The pressure-sensitive adhesive composition of the present invention comprises, as monomer components, at least 40% by mass of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, 0.5 to 20% by mass of a nitrogen-containing monomer, and alkylene. It is characterized by containing a (meth) acrylic polymer containing an oxide group-containing monomer in an amount of 0.5 to 40% by mass, an organic salt having a melting point of 150 ° C. or lower, and / or an alkali metal salt. The pressure-sensitive adhesive composition of the present invention, by containing a (meth) acrylic polymer containing a specific monomer in a specific ratio, is excellent in shearing force at the time of low-speed peeling, and has an organic salt having a melting point of 150 ° C. or less, and By containing an alkali metal salt, it is possible to obtain a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) having excellent anti-peeling antistatic properties, which is useful. Hereinafter, specific raw materials contained in the pressure-sensitive adhesive layer and a method for producing the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) will be described.

<(Meth) acrylic polymer>
The pressure-sensitive adhesive composition of the present invention is characterized by containing, as a monomer component, a (meth) acrylic polymer containing at least 40% by mass of a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms. . By blending the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms as a monomer component, it becomes easy to control the adhesive strength to an adherend (protected body) to be low, and it is easy to achieve light peelability and the like. An adhesive sheet having excellent removability is obtained.

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

  Among them, 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, etc. (Meth) acrylic monomers having an alkyl group having 6 to 14 carbon atoms are preferred. In particular, by using a (meth) acrylic monomer having an alkyl group having 6 to 14 carbon atoms as a main component (a component having the largest proportion as a monomer component), the adhesion to the adherend can be controlled to be low. Becomes easy, and excellent removability is obtained.

  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 mixture. The above (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms is contained in an amount of 40% by mass or more, preferably 50% by mass or more, more preferably 100% by mass, based on 100% by mass of the total amount of the constituting monomer components. , 60% by mass or more, more preferably 70 to 95% by mass. If the amount is less than 40% by mass, the wettability of the pressure-sensitive adhesive composition and the cohesive strength of the pressure-sensitive adhesive layer become poor, which is not preferable.

  The pressure-sensitive adhesive composition of the present invention is characterized by containing, as a monomer component, a (meth) acrylic polymer containing 0.5 to 20% by mass of a nitrogen-containing monomer. By blending the nitrogen-containing monomer as a monomer component, the cohesive force of the pressure-sensitive adhesive (layer) obtained by containing the (meth) acrylic polymer is improved, excellent shearing force can be developed, and curl control can be further improved. (Curl controllability) is also useful. Further, an organic salt or an alkali metal salt having a melting point of 150 ° C. or less (hereinafter sometimes simply referred to as “organic salt or the like”) is coordinated to a nitrogen atom contained in the (meth) acrylic polymer, It is assumed that an excellent shearing force can be realized by making it difficult for the organic salt or the like to bleed.

  Specific examples of the nitrogen-containing monomer include, for example, an amide group-containing monomer, an amino group-containing monomer, an imide group-containing monomer, and a cyano group-containing monomer.

  Examples of the amide group-containing monomer include acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N, N-dimethylacrylamide, and N, N-dimethylacrylamide. N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, 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, diacetoneacrylamide, N-vinylacetamide N, N'-methylenebisacrylamide, N, N-dimethylaminopropyl (meth) acrylamide, 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, diacetoneacrylamide N Vinylpyrrolidone, etc. N- vinyl caprolactam.

  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. ) 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) A) acrylate, t- Chill aminoethyl (meth) acrylate, and (meth) acryloyl morpholine and the like.

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

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

  The nitrogen-containing monomer may be used alone or as a mixture of two or more kinds. The nitrogen-containing monomer may be used in an amount of 100% by mass of the monomer component of the (meth) acrylic polymer. Is contained in an amount of 0.5 to 20% by mass, preferably 0.7 to 16% by mass, more preferably 0.9 to 10% by mass, and still more preferably 1 to 5% by mass. If the content of the nitrogen-containing monomer is less than 0.5% by mass, the effect of suppressing bleeding of organic salts and the like and the effect of reducing contamination of the adherend (protected body) may not be sufficiently obtained. On the other hand, when the content of the nitrogen-containing monomer is more than 20% by mass, the adhesive strength of the obtained pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) increases, and particularly when the pressure-sensitive adhesive sheet is applied as a surface protective film, This may cause destruction of the adherend, which is not preferable. On the other hand, when the content of the nitrogen-containing monomer is more than 20% by mass, interaction with an organic salt or the like becomes large, ionic conduction is hindered, and peeling antistatic property is sometimes lowered, which is not preferable.

  The pressure-sensitive adhesive composition of the present invention is characterized by containing, as a monomer component, a (meth) acrylic polymer containing 0.5 to 40% by mass of an alkylene oxide group-containing monomer. By blending the alkylene oxide group-containing monomer as a monomer component, it is possible to efficiently achieve both the effect of reducing the contamination of the adherend (protected object) and the effect of preventing peeling and charging, which is preferable.

  The alkylene oxide group-containing monomer may be used alone, or two or more kinds may be used as a mixture. However, based on 100% by mass of the total amount of the monomer component of the (meth) acrylic polymer, The oxide group-containing monomer is contained in an amount of 0.5 to 40% by mass, preferably 0.6 to 38% by mass, more preferably 0.7 to 36% by mass, and still more preferably 0.8 to 34% by mass. %. If the content of the alkylene oxide group-containing monomer exceeds 40% by mass, interaction with an organic salt or the like becomes large, ionic conduction is hindered, and peeling antistatic property is lowered, which is not preferable. If the amount is less than 0.5% by mass, the effect of suppressing bleed-out of an organic salt or the like and the effect of reducing contamination of an adherend (protected body) may not be sufficiently obtained, which is not preferable.

  The average number of moles of oxyalkylene units of the alkylene oxide group-containing monomer is preferably from 1 to 40, and more preferably from 3 to 40, from the viewpoint of compatibility with an organic salt or the like as an antistatic component. More preferably, it is more preferably 4 to 35, particularly preferably 5 to 30. When the average number of moles is 1 or more, the effect of reducing contamination of the adherend (protected body) tends to be efficiently obtained. On the other hand, if the average number of added moles is larger than 40, the interaction with an organic salt or the like is large, and the viscosity of the pressure-sensitive adhesive composition tends to increase, which is not preferable. In addition, the terminal of the oxyalkylene chain may be substituted with a hydroxyl group or another functional group, but for appropriately controlling the crosslinking density, for example, the terminal is substituted with an alkyl group, a phenyl group, or the like. Are more preferred.

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

  Further, the alkylene oxide group-containing monomer is more preferably a reactive monomer having an ethylene oxide group. By using a (meth) acrylic polymer having a reactive monomer having an ethylene oxide group as a base polymer, compatibility between the base polymer and an organic salt or the like is improved, and bleeding to an adherend is suitably suppressed, and low A contaminating adhesive composition is obtained.

  Examples of the alkylene oxide group-containing monomer include an alkylene oxide (meth) acrylate adduct and a reactive surfactant having a reactive substituent such as an acryloyl group, a methacryloyl group, or an allyl group in a molecule. .

  Specific examples of the alkylene oxide (meth) acrylate adduct include, for example, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, and polyethylene glycol-polybutylene glycol (meth) ) Acrylate, polypropylene glycol-polybutylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, butoxy polyethylene glycol (meth) acrylate, octoxy polyethylene glycol (meth) acrylate, lauroxy polyethylene Glycol (meth) acrylate, stearoxy polyethylene glycol Lumpur (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate, octoxypolyethylene glycol - polypropylene glycol (meth) acrylate. Among them, methoxypolyethylene glycol monoacrylate, ethoxydiethylene glycol acrylate and the like are preferably used.

  In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer preferably contains a carboxyl group-containing monomer as a monomer component in an amount of 0.01% by mass or more and less than 1% by mass. As the carboxyl group-containing monomer, one kind or two or more kinds can be used.

  By using the carboxyl group-containing monomer, the crosslinking reaction of the obtained pressure-sensitive adhesive (layer) can be promoted, and the aging time after the formation of the pressure-sensitive adhesive layer (the time required after the formation of the pressure-sensitive adhesive layer until the actual use characteristics are developed) And a pressure-sensitive adhesive sheet excellent in productivity can be obtained, which is useful. When a carboxyl group-containing monomer is used, it is a preferable embodiment to adjust the acid value of the (meth) acrylic polymer to be 29 or less. When the acid value of the (meth) acrylic polymer exceeds 29, the carboxyl group contained in the (meth) acrylic polymer interacts with an antistatic component, and the antistatic properties tend to deteriorate.

  The carboxyl group-containing monomer is preferably contained in an amount of 0.01% by mass or more and less than 1% by mass, more preferably 0.05% by mass or more, based on 100% by mass of the total amount of the monomer components of the (meth) acrylic polymer. Less than 0.2% by mass. When the content is within the above range, the crosslinking reaction of the pressure-sensitive adhesive composition can be effectively promoted, and the aging time after the pressure-sensitive adhesive layer is formed (the time required for the actual use characteristics to develop after the pressure-sensitive adhesive layer is formed) is reduced. It is useful because an adhesive sheet excellent in productivity can be obtained.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxylethyl (meth) acrylate, carboxylpentyl (meth) acrylate, 2- (meth) acryloyloxyethylhexahydrophthalic acid, and 2- (meth) acrylic acid. Loyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl maleic acid, carboxypolycaprolactone mono (meta ) Acrylate, 2- (meth) acryloyloxyethyltetrahydrophthalic acid, itaconic acid, maleic acid, fumaric acid and the like.

  Further, the (meth) acrylic polymer preferably contains a hydroxyl group-containing monomer as a monomer component. As the hydroxyl group-containing monomer, one kind or two or more kinds can be used.

  The use of the hydroxyl group-containing monomer makes it easier to control crosslinking of the pressure-sensitive adhesive composition, and thus to control the balance between improvement in wettability due to flow and reduction in adhesive force in peeling. Furthermore, unlike a carboxyl group or a sulfonate group which can generally act as a cross-linking site, a hydroxyl group has a moderate interaction with an organic salt or the like which is an antistatic component (antistatic agent). In terms of surface, it can be suitably used.

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

  The hydroxyl group-containing monomer is preferably contained in an amount of 0 to 15% by mass, more preferably 0.5 to 10% by mass, and still more preferably, based on 100% by mass of the total amount of the monomer components of the (meth) acrylic polymer. Is 1 to 8% by mass. It is preferable for it to be within the above-mentioned range because it is easy to control the balance between the wettability of the pressure-sensitive adhesive composition and the cohesive force and shear force of the obtained pressure-sensitive adhesive layer.

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

  The other polymerizable monomer can be used without any particular limitation as long as it does not impair the properties of the present invention. For example, a component having a functional group that acts as a cohesive force or shear force, a heat resistance improving component such as a vinyl ester monomer or an aromatic vinyl monomer, an adhesive group improving agent such as an epoxy group-containing monomer or a vinyl ether monomer, or a cross-linking base, Tg is used. For the purpose of controlling, methoxyethyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, and phenoxyethyl acrylate can be appropriately used. These polymerizable monomers may be used alone or as a mixture of two or more.

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

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

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

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

  The other polymerizable monomer can be used in an amount of 0 to 40 parts by mass, preferably 0 to 20 parts by mass, based on 100% by mass of the total amount of the monomer components of the (meth) acrylic polymer. More preferably, it is 10 parts by mass.

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

  The (meth) acrylic polymer preferably has a weight average molecular weight (Mw) of 100,000 to 5,000,000, more preferably 200,000 to 4,000,000, further preferably 300,000 to 3,000,000, and most preferably 400,000 to 4,000,000. One million. When the weight average molecular weight is smaller than 100,000, adhesive force tends to remain due to a decrease in the cohesive force of the pressure-sensitive adhesive layer. On the other hand, when the weight average molecular weight exceeds 5,000,000, the fluidity of the polymer is reduced, the wetting on the adherend (for example, a polarizing plate) becomes insufficient, and the adhesion between the adherend and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is reduced. It tends to cause blisters to occur in between. The weight average molecular weight refers to a value obtained by measurement by GPC (gel permeation chromatography).

  The glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C or lower, more preferably -10 ° C or lower, and further preferably -30 ° C or lower (usually -100 ° C or higher). When the glass transition temperature is higher than 0 ° C., the (meth) acrylic polymer does not easily flow, for example, the wettability to an adherend (for example, a polarizing plate) becomes insufficient, and the adhesive between the adherend and the pressure-sensitive adhesive sheet is used. It tends to cause blistering between layers. In particular, by setting the glass transition temperature to -61 ° C or lower, it becomes easy to obtain a pressure-sensitive adhesive layer having excellent wettability to an adherend and light peelability. The glass transition temperature of the (meth) acrylic polymer can be adjusted within the above range by appropriately changing the monomer components and the composition ratio used.

<Antistatic component>
The pressure-sensitive adhesive composition of the present invention is characterized by containing an organic salt having a melting point of 150 ° C. or lower and / or an alkali metal salt. By containing an organic salt having an melting point of 150 ° C. or less and / or an alkali metal salt as an antistatic component (antistatic agent), excellent exfoliation antistatic properties can be imparted. The pressure-sensitive adhesive layer formed by cross-linking the pressure-sensitive adhesive composition containing the antistatic component as described above can prevent an adherend (for example, a polarizing plate) that has not been antistatic when peeled off. Thus, a pressure-sensitive adhesive sheet with reduced contamination of the adherend can be obtained. For this reason, it becomes very useful as a surface protection film in the technical field related to optical and electronic parts where charging and contamination are particularly serious problems.

  Further, the reason why excellent peeling antistatic properties are obtained by using an organic salt having the melting point of 150 ° C. or less as the antistatic component (antistatic agent) is not clear, but the melting point is 150 ° C. or less. Since the organic salt of (1) has a lower melting point (melting point of 150 ° C. or less) than a normal antistatic component, it is considered that molecular movement is easy and excellent antistatic ability is obtained. In particular, when preventing the charge on the adherend, the organic salt having the melting point of 150 ° C. or less is transferred to the adherend in a very small amount, thereby achieving excellent antistatic peeling property on the adherend. it is conceivable that. In particular, the melting point of the organic salt is preferably 100 ° C. or less, more preferably 80 ° C. or less, and most preferably room temperature (25 ° C.) or less. By using such an organic salt, the transfer of the organic salt to an adherend can be performed more efficiently, so that excellent antistatic property for peeling can be obtained.

  In addition, since the organic salt having a melting point of 150 ° C. or less is liquid at any temperature of 150 ° C. or less, it can be easily added to a pressure-sensitive adhesive and dispersed or dissolved as compared with a solid salt. Further, when the organic salt having a melting point of 150 ° C. or less is an ionic liquid, the ionic liquid has no vapor pressure (non-volatile), so that it does not disappear over time and the antistatic property for peeling is continuously obtained. Have. The ionic liquid refers to a molten salt (ionic compound) that has a melting point of 150 ° C. or less and is in a liquid state.

  The organic salt having a melting point of 150 ° C. or lower is preferably at least one selected from the group consisting of a nitrogen-containing onium salt, a sulfur-containing onium salt, and a phosphorus-containing onium salt. Those comprising an organic cation component represented by the formulas (A) to (E) and an anion component are preferably used. By the organic salt having these cations, one having further excellent antistatic property for peeling can be obtained.

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

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

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

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

R _P in the formula (E) represents a hydrocarbon group having 1 to 18 carbon atoms, a part of the hydrocarbon group may be substituted by a functional group with a heteroatom.

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

  Specific examples include, for example, 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl -3-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidium Cation, 1-methyl-1-butylpyrrolidinium cation, 1-methyl-1-pentylpyrrolidinium cation, 1-methyl-1-hexylpyrrolidinium cation, 1-methyl-1-heptylpyrrolidinium Cation, 1-ethyl-1-propylpyrrolidini Cation, 1-ethyl-1-butylpyrrolidinium cation, 1-ethyl-1-pentylpyrrolidinium cation, 1-ethyl-1-hexylpyrrolidinium cation, 1-ethyl-1-heptylpyrrolidinium Cation, 1,1-dipropylpyrrolidinium cation, 1-propyl-1-butylpyrrolidinium cation, 1,1-dibutylpyrrolidinium cation, pyrrolidinium-2-one cation, 1-propylpiperidinium cation, 1-pentylpiperidinium cation, 1,1-dimethylpiperidinium cation, 1-methyl-1-ethylpiperidinium cation, 1-methyl-1-propylpiperidinium cation, 1-methyl-1-butylpi Peridinium cation, 1-methyl-1-pentylpiperidinium cation 1-methyl-1-hexylpiperidinium cation, 1-methyl-1-heptylpiperidinium cation, 1-ethyl-1-propylpiperidinium cation, 1-ethyl-1-butylpiperidinium cation, 1 -Ethyl-1-pentylpiperidinium cation, 1-ethyl-1-hexylpiperidinium cation, 1-ethyl-1-heptylpiperidinium cation, 1,1-dipropylpiperidinium cation, 1-propyl -1-butylpiperidinium cation, 1,1-dibutylpiperidinium cation, 2-methyl-1-pyrroline cation, 1-ethyl-2-phenylindole cation, 1,2-dimethylindole cation, 1-ethylcarbazole Cations, N-ethyl-N-methylmorpholinium cations and the like. Can be

  Examples of the cation represented by the formula (B) include an imidazolium cation, a tetrahydropyrimidinium cation, and a dihydropyrimidinium cation.

  Specific examples include, for example, 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, Xyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazo Lium cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3 -Dimethylimidazolium cation, 1- (2-meth (Siethyl) -3-methylimidazolium cation, 1,3-dimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium cation Cation, 1,2,3,4-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium Cation, 1,3-dimethyl-1,4-dihydropyrimidinium cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium Cation, 1,2,3-trimethyl-1,6-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium click Emissions, such as 1,2,3,4-tetramethyl-1,6-dihydropyrimidinium cation.

  Examples of the cation represented by the formula (C) include a pyrazolium cation and a pyrazolinium cation.

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

  Examples of the cation represented by the formula (D) include a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraalkylphosphonium cation, and a case where a part of the alkyl group is substituted with an alkenyl group, an alkoxyl group, or an epoxy group. And others.

  Specific examples include, for example, tetramethylammonium cation, tetraethylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptylammonium cation, triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation , N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, glycidyltrimethylammonium cation, trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, trihexylsulfonium cation, diethylmethylsulfonium cation, dibutyl Ethyl sulfonium click Dimethyl decyl sulfonium cation, tetramethyl phosphonium cation, tetraethyl phosphonium cation, tetrabutyl phosphonium cation, tetrahexyl phosphonium cation, tetraoctyl phosphonium cation, triethyl methyl phosphonium cation, tributyl ethyl phosphonium cation, trimethyl decyl phosphonium cation, diallyl dimethyl ammonium cation And tributyl- (2-methoxyethyl) phosphonium cation. Above all, asymmetric such as triethylmethylammonium cation, tributylethylammonium cation, trimethyldecylammonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, dimethyldecylsulfonium cation, triethylmethylphosphonium cation, tributylethylphosphonium cation, trimethyldecylphosphonium cation, etc. Tetraalkylammonium cation, trialkylsulfonium cation, tetraalkylphosphonium cation, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N, N -Dimethyl-N-ethyl-N-propyla Monium cation, N, N-dimethyl-N-ethyl-N-butylammonium cation, N, N-dimethyl-N-ethyl-N-pentylammonium cation, N, N-dimethyl-N-ethyl-N-hexylammonium cation N, N-dimethyl-N-ethyl-N-heptylammonium cation, N, N-dimethyl-N-ethyl-N-nonylammonium cation, N, N-dimethyl-N, N-dipropylammonium cation, N-diethyl-N-propyl-N-butylammonium cation, N, N-dimethyl-N-propyl-N-pentylammonium cation, N, N-dimethyl-N-propyl-N-hexylammonium cation, N, N- Dimethyl-N-propyl-N-heptylammonium cation, N, N-di Tyl-N-butyl-N-hexylammonium cation, N, N-diethyl-N-butyl-N-heptylammonium cation, N, N-dimethyl-N-pentyl-N-hexylammonium cation, N, N-dimethyl- N, N-dihexylammonium cation, trimethylheptylammonium cation, N, N-diethyl-N-methyl-N-propylammonium cation, N, N-diethyl-N-methyl-N-pentylammonium cation, N, N-diethyl -N-methyl-N-heptylammonium cation, N, N-diethyl-N-propyl-N-pentylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylheptylammonium cation, N, N- Dipropyl-N-methyl-N-ethylammonium cation, N, N-dipropyl-N-methyl-N-pentylammonium cation, N, N-dipropyl-N-butyl-N-hexylammonium cation, N, N-dipropyl- N, N-dihexylammonium cation, N, N-dibutyl-N-methyl-N-pentylammonium cation, N, N-dibutyl-N-methyl-N-hexylammonium cation, trioctylmethylammonium cation, N-methyl- The N-ethyl-N-propyl-N-pentylammonium cation is preferably used.

Examples of the cation represented by the formula (E) include a sulfonium cation. Further, the formula Specific examples of R _P in (E) is a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, An octadecyl group;

On the other hand, the anion component is not particularly limited as long as it satisfies that the melting point becomes an organic salt having a melting point of 150 ° C. or less. For example, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl _{7 ^{-, BF 4 -, PF 6}} -, SCN -, ClO 4 -, NO 3 -, CH 3 COO -, CF 3 COO -, CH 3 SO 3 -, CF 3 SO 3 -, C 4 F 9 SO 3 - , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) ₂ N ⁻ , (CF ₃ (SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , HF ₂ ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) _{^{2 N -, C 3 F 7}} COO -, (CF 3 _{^{O 2) (CF 3 CO)}} N -, C 9 H 19 COO -, (CH 3) 2 PO 4 -, (C 2 H 5) 2 PO 4 -, C 2 H 5 OSO 3 -, C 6 H 13 OSO ₃ ⁻ , C ₈ H ₁₇ OSO ₃ ⁻ , CH ₃ (OC ₂ H ₄ ) ₂ OSO ₃ ⁻ , C ₆ H ₄ (CH ₃ ) SO ₃ ⁻ , (C ₂ F ₅ ) ₃ PF ₃ ⁻ , CH ₃ CH (OH) COO ⁻ , (FSO ₂ ) ₂ N— ^{and the} like are used.

Further, as the anion component, an anion represented by the following formula (F) can be used.

  As the anion component, an anion component containing a fluorine atom is particularly preferably used because an organic salt having a low melting point can be obtained.

Specific examples of the organic salt having a melting point of 150 ° C. or lower used in the present invention are appropriately selected from combinations of the cation component and the anion component, and include, for example, 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium Hexafluorophosphate, 1-butyl-3-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide, 1-butyl-3- Methylpyridinium bis (pentafluoroethanesulfonyl) imide, 1-hexylpyridinium tetrafluoroborate, 1,1-dimethylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-ethyl Loridinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1- Pentylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-hexylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-heptylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-propylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-pentylpyrrolidinium (Trifluoromethanesulfonyl) imide, 1-ethyl-1-hexylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-heptylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1,1- Dipropylpyrrolidinium bis (triple methanesulfonyl) imide, 1-propyl-1-butylpyrrolidinium bis (trifluoromethanesulfonyl) imide, 1,1-dibutylpyrrolidinium bis (triple methanesulfonyl) imide, 1 -Propylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-pentylbiberidinium bis (trifluoromethanesulfonyl) imide, 1,1-dimethylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1 -Ethylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-propylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-butylpiperidinium bis (trifluoromethanesulfonyl) imide, 1 -Methyl-1-pentylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-hexylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-methyl-1-heptylpiperidinium bis (trifluoromethane Sulfonyl) imide, 1-ethyl-1-propylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-butylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-pentylpiper N-bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-hexylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-ethyl-1-heptylpiperidinium bis (trifluoromethanesulfonyl) imide, 1,1- Dipropylpiperidinium bis (trifluoromethanesulfonyl) imide, 1-propyl-1-butylpiperidiniumpis (trifluoromethanesulfonyl) imide, 1,1-dibutylpiperidinium bis (trifluoromethanesulfonyl) imide, 1,1 -Dimethylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-ethylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-propylpyrrolidinium bis (pentafluoroe N-sulfonyl) imide, 1-methyl-1-butylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-pentylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1- Xylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-heptylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-propylpyrrolidinium bis (pentafluoroethanesulfonyl) Imide, 1-ethyl-1-butylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-pentylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-hexylpyrrolidine Numium bis (pentafluoroe Tansulfonyl) imide, 1-ethyl-1-heptylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1,1-dipropylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-propyl-1-butyl Pyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1,1-dibutylpyrrolidinium bis (pentafluoroethanesulfonyl) imide, 1-propylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-pentylpiperidinium Bis (bentafluoroethanesulfonyl) imide, 1,1-dimethylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-ethylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1 − Pyrpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-butylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-pentylpiperidinium bis (pentafluoroethanesulfonyl) imide 1-methyl-1-hexylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-methyl-1-heptylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-propylpiperidi Ammonium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-butylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-pentylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1- Ethyl-1- Xylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-1-heptylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1,1-dipropylpiperidinium bis (pentafluoroethanesulfonyl) imide , 1-propyl-1-butylpiperidinium bis (pentafluoroethanesulfonyl) imide, 1,1-dibutylpiperidinium bis (pentafluoroethanesulfonyl) imide, 2-methyl-1-pyrrolinetetrafluoroborate, 1- Ethyl-2-phenylindole tetrafluoroborate, 1,2-dimethylindole tetrafluoroborate, 1-ethylcarbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3- Methyl imidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium heptafluorobutyrate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3 -Methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium bis (pentafluoro Ethanesulfonyl) imide, 1-ethyl-3-methylimidazolium tris (trifluoromethanesulfonyl) methide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methyl Midazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoroacetate, 1-butyl-3-methylimidazolium heptafluorobutyrate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl -3-methylimidazolium perfluorobutanesulfonate, 1-butyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride 1-hexyl-3-methylimidazolium tetrafluoroborate, 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfate 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-dimethyl- 3-propylimidazolium bis (trifluoromethanesulfonyl) imide, 1-methylpyrazolium tetrafluoroborate, 2-methylpyrazolium tetrafluoroporate, 1-ethyl-2,3,5-trimethylpyrazolium bis (trifluoro 1-propyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide, 1-butyl-2,3,5-trimethylpyrazolium bis (trifluoromethanesulfonyl) imide, 1 -Ethyl -2,3,5-trimethylpyrazolium bis (pentafluoroethanesulfonyl) imide, 1-propyl-2,3,5-trimethylpyrazoliumbis (pentafluoroethanesulfonyl) imide, 1-butyl-2,3 , 5-Trimethylpyrazolium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-2,3,5-trimethylpyrazoliumbis (trifluoromethanesulfonyl) trifluoroacetamide, 1-propyl-2,3,5- Trimethylpyrazolium bis (trifluoromethanesulfonyl) trifluoroacetamide, 1-butyl-2,3,5-trimethylpyrazoliumbis (trifluoromethanesulfonyl) trifluoroacetamide, 1-ethyl-2,3,5-trimethylpyramide Zolinium bis (trifluoromethane Rufonyl) imide, 1-propyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) imide, 1-butyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) imide, 1- Ethyl-2,3,5-trimethylpyrazolinium bis (pentafluoroethanesulfonyl) imide, 1-propyl-2,3,5-trimethylpyrazolinium bis (pentafluoroethanesulfonyl) imide, 1-butyl-2, 3,5-trimethylpyrazolinium bis (pentafluoroethanesulfonyl) imide, 1-ethyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) trifluoroacetamide, 1-propyl-2,3,5 -Trimethylpyrazolinium bis (trifluoro (Methanesulfonyl) trifluoroacetamide, 1-butyl-2,3,5-trimethylpyrazolinium bis (trifluoromethanesulfonyl) trifluoroacetamide, tetrapentylammonium trifluoromethanesulfonate, tetrapentylammonium bis (trifluoromethanesulfonyl) imide, tetra Hexyl ammonium trifluoromethanesulfonate, tetrahexylammonium bis (trifluoromethanesulfonyl) imide, tetraheptylammonium trifluoromethanesulfonate, tetraheptylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium tetrafluoroborate, diallyldimethylammonium trifluoromethanesulfonate, Diallyl dimethyl Ammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium bis (pentafluoroethanesulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoroborate, N, N-diethyl-
N-methyl-N- (2-methoxyethyl) ammonium trifluoromethanesulfonate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl- N-methyl-N- (2-methoxyethyl) ammonium bis (pentafluoroethanesulfonyl) imide, glycidyltrimethylammonium trifluoromethanesulfonate, glycidyltrimethylammoniumbis (trifluoromethanesulfonyl) imide, glycidyltrimethylammonium bis (pentafluoroethanesulfonyl) imide , Tetraoctylphosphonium trifluoromethanesulfonate, tetraoctylphosphonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl -N-ethyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-butylammoniumbis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N -Pentyl ammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-heptylammonium bis ( Trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-nonylammoniumbis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N-dipropylammoniumbis (trifluoromethanesulfonyl) imide, N , N- Dimethyl-N-propyl-N-butylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl- N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-heptylammoniumbis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-hexylammoniumbis ( Trifluoromethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-heptylammoniumbis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-pentyl-N-hexylammoniumbis (trifluoromethane Rufonyl) imide, N, N-dimethyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide, trimethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-propylammoniumbis (Trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide , N, N-diethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, triethylpropylammonium bis (trifluoromethanesulfonyl) imide, triethylpe Tylammonium bis (trifluoromethanesulfonyl) imide, triethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl-N-ethylammoniumbis (trifluoromedansulfonyl) imide, N, N-dipropyl- N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N, N-dihexyl Ammonium bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl-N-hexyl Ammonium bis (trifluoromethanesulfonyl) imide, trioctylmethylammonium bis (trifluoromethanesulfonyl) imide, N-methyl-N-ethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, 1-butylpyridinium ( (Trifluoromethanesulfonyl) trifluoroacetamide, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-ethyl-3-methylimidazolium (trifluoromethanesulfonyl) trifluoroacetamide, N-ethyl-N-methyl Morpholinium thiocyanate, 4-ethyl-4-methylmorpholinium methyl carbonate and the like can be mentioned.

  As the organic salt having a melting point of 150 ° C. or lower, a commercially available organic salt may be used, but the organic salt may be synthesized as follows. The method for synthesizing the organic salt having a melting point of 150 ° C. or less is not particularly limited as long as the desired organic salt can be obtained. In general, the literature “Ionic liquids—the forefront of development and the future—” ) Published by CMC Publishing Co.], halide method, hydroxide method, acid ester method, complex formation method, neutralization method and the like.

  The synthesis method of the halide method, hydroxide method, acid ester method, complex formation method, and neutralization method is shown below using a nitrogen-containing onium salt as an example, but other sulfur-containing onium salts, phosphorus-containing onium salts, etc. The above method can also be used for the organic salt (for example, ionic liquid) having a melting point of 150 ° C. or lower.

The halide method is a method performed by a reaction represented by the following formulas (1) to (3). First, a tertiary amine is reacted with an alkyl halide to obtain a halide. (Reaction formula (1), chlorine, bromine, and iodine are used as halogens) An acid (HA) or a salt (MA, M) having an anion structure (A ⁻ ) of an organic salt intended for the obtained halide is used. Reaction with a desired anion such as ammonium, lithium, sodium, or potassium) to obtain a desired organic salt (R ₄ NA).

The hydroxide method is a method performed by a reaction as shown in (4) to (8). First, halide (R ₄ NX) is subjected to ion exchange membrane electrolysis (reaction formula (4)), OH-type ion exchange resin method (reaction formula (5)) or reaction with silver oxide (Ag ₂ O) (reaction formula ( 6)) to obtain a hydroxide (R ₄ NOH). (Halogen is chlorine, bromine or iodine.) The obtained hydroxide is subjected to the reaction of the reaction formulas (7) to (8) in the same manner as in the above-mentioned halogenation method to obtain the desired organic salt (R ₄ NA ) Is obtained.

The acid ester method is a method performed by a reaction as shown in (9) to (11). First, a tertiary amine (R ₃ N) is reacted with an acid ester to obtain an acid ester. (Reaction formula (9), as the acid ester, esters of inorganic acids such as sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, and carbonic acid, and esters of organic acids such as methanesulfonic acid, methylphosphonic acid, and formic acid) are used. The desired organic salt (R ₄ NA) is obtained from the obtained acid ester by using the reactions of Reaction Formulas (10) to (11) in the same manner as in the above-mentioned halogenation method. Further, by using methyl trifluoromethanesulfonate, methyl trifluoroacetate, or the like as an acid ester, an organic salt can be directly obtained.

The complex forming method is a method performed by a reaction as shown in (12) to (15). First, a quaternary ammonium halide (R ₄ NX), a quaternary ammonium hydroxide (R ₄ NOH), a quaternary ammonium carbonate (R ₄ NOCO ₂ CH ₃ ) and the like are converted into hydrogen fluoride (HF), Reaction with ammonium fluoride (NH ₄ F) gives a quaternary ammonium fluoride salt. (Reaction formulas (12) to (14)) The obtained quaternary ammonium fluoride salt is complexed with a fluoride such as BF ₃ , AlF ₃ , PF ₅ , AsF ₅ , SbF ₅ , NbF ₅ , TaF _{5 and the} like. , An organic salt can be obtained. (Reaction formula (15))

The neutralization method is a method performed by a reaction as shown in (16). Tertiary amine and HBF ₄ , HPF ₆ , CH ₃ COOH, CF ₃ COOH, CF ₃ SO ₃ H, (CF ₃ SO ₂ ) ₂ NH, (CF ₃ SO ₂ ) ₃ CH, (C ₂ F ₅ SO ₂ ) it can be obtained by reacting an organic acid such as ₂ NH.

  R in the formulas (1) to (16) represents hydrogen or a hydrocarbon group having 1 to 20 carbon atoms, and a part of the hydrocarbon group may be a functional group substituted with a hetero atom. Good.

  In addition, the said organic salt may be used independently and may be used in mixture of 2 or more types.

Since the alkali metal salt has high ion dissociation property, it is preferable in that it exhibits excellent exfoliation antistatic ability even in a small amount. Examples of the alkali metal salt include a cation composed of Li ⁺ , Na ⁺ , and K ⁺ , and Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , and SCN. ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , C ₉ H ₁₉ COO ⁻ , CF ₃ COO ⁻ , C ₃ F ₇ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₄ F _9. SO ₃ ⁻ , C ₂ H ₅ OSO ₃ ⁻ , C ₆ H ₁₃ OSO ₃ ⁻ , C ₈ H ₁₇ OSO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , _{^{HF 2 -, (CN) 2}} N ^{_{, (CF 3 SO 2) (}} CF 3 CO) N -, (CH 3) 2 PO 4 -, (C 2 H 5) 2 PO 4 -, CH 3 (OC 2 H 4) 2 OSO 3 -, C 6 A metal salt composed of an anion consisting of H ₄ (CH ₃ ) SO ₃ ⁻ , (C ₂ F ₅ ) ₃ PF ₃ ⁻ , CH ₃ CH (OH) COO ⁻ , and (FSO ₂ ) ₂ N ⁻ is preferable. Used for More _{preferably, LiBr, LiI, LiBF 4,} LiPF 6, LiSCN, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, Li (C 2 F 5 SO 2) 2 N, Li (FSO 2 ) ₂ N, lithium salt such as Li (CF ₃ SO ₂ ) ₃ C, more preferably LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li ( C ₃ F ₇ SO ₂ ) ₂ N, Li (C ₄ F ₉ SO ₂ ) ₂ N, Li (FSO ₂ ) ₂ N, and Li (CF ₃ SO ₂ ) ₃ C are used. These alkali metal salts may be used alone or in combination of two or more.

  The content of the organic salt or the like (the organic salt having a melting point of 150 ° C. or less and / or the alkali metal salt) is preferably 4.9 parts by mass or less based on 100 parts by mass of the (meth) acrylic polymer. The amount is more preferably 0.001 to 2.5 parts by mass, more preferably 0.05 to 1 part by mass, and most preferably 0.1 to 0.5 part by mass. It is preferable that the content be in the above-mentioned range, since it is easy to achieve both anti-peeling and anti-staining properties.

<Alkylene oxide group-containing compound containing no organopolysiloxane having a number average molecular weight of 10,000 or less>
The pressure-sensitive adhesive composition of the present invention further contains an alkylene oxide group-containing compound containing no organopolysiloxane having a number average molecular weight of 10,000 or less (hereinafter sometimes simply referred to as “alkylene oxide group-containing compound”). Preferably. By containing the alkylene oxide group-containing compound in the pressure-sensitive adhesive, a pressure-sensitive adhesive having excellent wettability to an adherend can be obtained. Further, in the pressure-sensitive adhesive sheet (surface protective film) formed of the pressure-sensitive adhesive composition containing the alkylene oxide group-containing compound, the alkylene oxide group-containing compound can be transferred to an adherend in a small amount, whereby The wettability of the surface of the adherend is improved, and in the step after the peeling of the pressure-sensitive adhesive sheet (surface protective film), when the pressure-sensitive adhesive or the adhesive is further applied to the adherend, the wettability is easily spread. When sticking the pressure-sensitive adhesive sheet, it is possible to easily develop good tackiness (adhesion), which is useful.

  Specific examples of the alkylene oxide group-containing compound include, for example, polyoxyalkylene alkylamine, polyoxyalkylene diamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkylphenyl ether, polyoxyalkylene alkyl ether Nonionic surfactants such as polyoxyalkylene alkyl allyl ether, polyoxyalkylene alkyl phenyl allyl ether; polyoxyalkylene alkyl ether sulfate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether sulfate Anionic surfactants such as ester salts and polyoxyalkylene alkylphenyl ether phosphate salts In addition, a cationic surfactant having a polyoxyalkylene chain (polyalkylene oxide chain) or an amphoteric surfactant, a polyether compound having a polyoxyalkylene chain (including a derivative thereof), or having a polyoxyalkylene chain An acrylic compound (including its derivative), an ester compound having a polyoxyalkylene chain (and its derivative), and the like can be given. Further, a polyoxyalkylene chain-containing monomer may be blended with the acrylic polymer as the alkylene oxide group-containing compound. The alkylene oxide group-containing compounds may be used alone or in combination of two or more.

  Specific examples of the polyether compound having a polyoxyalkylene chain include a block copolymer of polypropylene glycol (PPG) -polyethylene glycol (PEG), a block copolymer of PPG-PEG-PPG, and a block copolymer of PEG-PPG-PEG. And block copolymers. Derivatives of the polyether compound having a polyoxyalkylene chain include oxypropylene group-containing compounds having an etherified terminal (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.) and oxypropylene groups having an acetylated terminal. -Containing compounds (terminal acetylated PPG and the like).

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

The (meth) acrylate polymer having an oxyalkylene group is preferably a polymer containing an alkylene oxide (meth) acrylate as a monomer component. Specific examples of the alkylene oxide (meth) acrylate include ethylene. Examples of the glycol group-containing (meth) acrylate include methoxypolyethylene glycol (meth) acrylate such as methoxydiethylene glycol (meth) acrylate and methoxytriethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, ethoxytriethylene glycol ( Ethoxy polyethylene glycol (meth) acrylate such as meth) acrylate, butoxy-diethylene glycol (meth) acrylate, butoxy-triethyl Butoxy-polyethylene glycol (meth) acrylate type such as ethylene glycol (meth) acrylate, phenoxy-polyethylene glycol (meth) acrylate type such as phenoxy-diethylene glycol (meth) acrylate, phenoxy-triethylene glycol (meth) acrylate, 2-ethylhexyl -Polyethylene glycol (meth) acrylate, nonylphenol-polyethylene glycol (meth) acrylate type, and methoxypolypropylene glycol (meth) acrylate type such as methoxydipropylene glycol (meth) acrylate.

  Further, other monomer components other than the alkylene oxide (meth) acrylate may be used as the monomer components. Specific examples of other monomer components include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, and isobutyl (meth) acrylate. , Hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate Acrylate and / or methacrylate having an alkyl group having 1 to 14 carbon atoms, such as isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. Door and the like.

  Further, other monomer components other than the alkylene oxide (meth) acrylate include (meth) acrylates containing carboxyl groups, (meth) acrylates containing phosphoric acid groups, (meth) acrylates containing cyano groups, vinyl esters, and aromatic vinyl compounds. Acid anhydride group-containing (meth) acrylate, hydroxyl group-containing (meth) acrylate, amide group-containing (meth) acrylate, amino group-containing (meth) acrylate, epoxy group-containing (meth) acrylate, N-acryloylmorpholine, vinyl ethers Etc. can be used as appropriate.

  Specific examples of the ester compound having a polyoxyalkylene chain include diethylene glycol di-2-ethylhexonate, tetraethylene glycol di-2-ethylhexonate, polyethylene glycol di-2-ethylhexonate, and triethylene glycol di-2-ethylhexonate. Glycol diethyl butyrate, polyethylene glycol diethyl butyrate, polypropylene glycol diethylhexonate, triethylene glycol dibenzoate, tetraethylene glycol dibenzoate, polyethylene glycol dibenzoate, polypropylene glycol dibenzoate, or polyethylene glycol-2-ethyl Xonate benzoate and the like.

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

  As the molecular weight of the alkylene oxide group-containing compound not containing the organopolysiloxane, the number average molecular weight (Mn) is preferably 10,000 or less, more preferably 100 to 5000, and still more preferably 400 to 3000. When Mn is larger than 10,000, the compatibility with the (meth) acrylic polymer is reduced, and the pressure-sensitive adhesive layer tends to be whitened. When Mn is smaller than 100, contamination by the alkylene oxide group-containing compound may easily occur. Here, Mn refers to a value in terms of polystyrene obtained by GPC (gel permeation chromatography).

  Specific examples of commercially available products of the alkylene oxide group-containing compound not containing the organopolysiloxane include, for example, Adecapluronic 17R-4, Adecapluronic 25R-2 (all manufactured by ADEKA), and Emulgen 120 (Kao). And the like).

  The compounding amount of the alkylene oxide group-containing compound not containing the organopolysiloxane can be, for example, 0.005 to 20 parts by mass, preferably 0.01 to 20 parts by mass, based on 100 parts by mass of the (meth) acrylic polymer. 10 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and most preferably 0.1 to 1 part by mass. If the amount is too small, the effect of preventing bleeding of the antistatic component is reduced. If the amount is too large, contamination with the alkylene oxide group-containing compound tends to occur, which is not preferable.

<Organopolysiloxane having oxyalkylene chain>
The pressure-sensitive adhesive composition of the present invention can contain an organopolysiloxane having an oxyalkylene chain, and more preferably contains an organopolysiloxane having an oxyalkylene main chain. It is presumed that the use of the organopolysiloxane reduces the surface free energy of the surface of the pressure-sensitive adhesive, so that even with a small content, both low contamination and light peeling can be achieved.

As the organopolysiloxane, a known organopolysiloxane having a polyoxyalkylene main chain can be appropriately used, and is preferably represented by the following formula.

(Wherein, R ₁ and / or R ₂ has an oxyalkylene chain having 1 to 6 carbon atoms, and the alkylene group in the oxyalkylene chain may be linear or branched, and the oxyalkylene chain May be an alkoxy group or a hydroxyl group, and _one of R _{1 and} R ₂ may be a hydroxyl group, or may be an alkyl group or an alkoxy group; (A part of the group or the alkoxy group may be a functional group substituted with a hetero atom. N is an integer of 1 to 300.)

  As the organopolysiloxane, one having a siloxane-containing site (siloxane site) as a main chain and an oxyalkylene chain bonded to the terminal of the main chain is used. By using the organosiloxane having the oxyalkylene chain, compatibility with (meth) acrylic polymer and organic salt (organic salt having a melting point of 150 ° C. or less and / or alkali metal salt) can be balanced, It is presumed that light peeling is realized.

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

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

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

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

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

In addition to the organosiloxane having an oxyalkylene chain in the main chain (bonding), it is also possible to use an organosiloxane having an oxyalkylene chain in the side chain (bonding). It is a more preferred embodiment to use an organosiloxane having an alkylene chain. As the organopolysiloxane, a known organopolysiloxane having a polyoxyalkylene side chain can be used as appropriate, but is preferably represented by the following formula.

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

Further, as the organopolysiloxane in the present invention, for example, the following configuration can be used. Specifically, R ₁ in the formula is a monovalent group exemplified by an alkyl group such as a methyl group, an ethyl group and a propyl group, an aryl group such as a phenyl group and a tolyl group, or an alkyl group such as a benzyl group and a phenethyl group. It is an organic group and each may have a substituent such as a hydroxyl group. As R ₂ , R ₃ and R _4, an alkylene group having 1 to 8 carbon atoms such as a methylene group, an ethylene group and a propylene group can be used. Here, R ₃ and R ₄ are different alkylene groups, and R ₂ may be the same as or different from R ₃ or R ₄ . In order to increase the concentration of an organic salt or the like (an organic salt having a melting point of 150 ° C. or less and / or an alkali metal salt) that can be dissolved in the polyoxyalkylene side chain, one of R ₃ and R ₄ is It is preferably an ethylene group or a propylene group. R ₅ may be a monovalent organic group exemplified by an alkyl group such as a methyl group, an ethyl group and a propyl group or an acyl group such as an acetyl group and a propionyl group, each having a substituent such as a hydroxyl group. May be. These compounds may be used alone or as a mixture of two or more. In addition, the molecule may have a reactive substituent such as a (meth) acryloyl group, an allyl group, and a hydroxyl group. Among the organosiloxanes having a polyoxyalkylene side chain, an organosiloxane having a polyoxyalkylene side chain having a hydroxyl group terminal is preferable because it is presumed that the compatibility is easily balanced.

  Specific examples of the organosiloxane include KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, and KF as commercial products. -642, KF-643, KF-6022, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017, X-22-2516 (all Shin-Etsu Chemical Co., Ltd.) SF8428, FZ-2162, SH3749, FZ-77, L-7001, FZ-2104, FZ-2110, L-7002, FZ-2122, FZ-2164, FZ-2203, FZ-7001, SH8400, SH8700 , SF8410, SF8422 (all manufactured by Dow Corning Toray), TSF-44 0, TSF-4441, TSF-4445, TSF-4450, TSF-4446, TSF-4452, TSF-4460 (manufactured by Momentive Performance Materials), BYK-333, BYK-307, BYK-377, BYK-UV3500, BYK-UV3570 (manufactured by BYK Japan KK) and the like. These compounds may be used alone or as a mixture of two or more.

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

  Further, the content of the organopolysiloxane is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and still more preferably 100 parts by mass of the (meth) acrylic polymer. Is 0.1 to 1 part by mass. It is preferable that the content is in the above-mentioned range, since it is easy to achieve both anti-peeling antistatic property and light-peeling property (removability).

<Crosslinking agent>
It is preferable that the pressure-sensitive adhesive composition of the present invention contains a crosslinking agent. In the present invention, a pressure-sensitive adhesive layer can be formed by crosslinking using a cross-linking agent contained in the pressure-sensitive adhesive composition. For example, when the pressure-sensitive adhesive contains the (meth) acrylic polymer, the crosslinking is performed by appropriately adjusting the constitutional unit, the composition ratio of the (meth) acrylic polymer, the selection and the addition ratio of the crosslinking agent, and the like. Thus, a pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) having more excellent heat resistance can be obtained.

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

  Examples of the isocyanate compound (isocyanate-based crosslinking agent) include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI) and dimer acid diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate. Aliphatic isocyanates such as (IPDI), aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate (XDI); Nurate bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond, oxo Polyisocynate modified product obtained by modifying the like trione bond. For example, as commercial products, trade names Takenate 300S, Takenate 500, Takenate D165N, Takenate D178N (above, manufactured by Takeda Pharmaceutical Co., Ltd.), Sumidur T80, Sumidur L, Desmodur N3400 (above, manufactured by Sumika Bayer Urethane Co., Ltd.) , Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (all manufactured by Nippon Polyurethane Industry Co., Ltd.). These isocyanate compounds may be used alone or in combination of two or more.

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

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

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

  The content of the crosslinking agent used in the present invention is preferably, for example, 0.01 to 10 parts by mass, and preferably 0.1 to 8 parts by mass, based on 100 parts by mass of the (meth) acrylic polymer. It is more preferably contained, more preferably 0.5 to 5 parts by mass, and most preferably 1.0 to 2.5 parts by mass. When the content is less than 0.01 parts by mass, the crosslinking formation by the crosslinking agent becomes insufficient, the cohesive force of the obtained pressure-sensitive adhesive layer becomes small, and sufficient heat resistance may not be obtained. It tends to cause glue residue. On the other hand, when the content exceeds 10 parts by mass, the cohesive force of the polymer is large, the fluidity is reduced, the wetting on the adherend (for example, a polarizing plate) becomes insufficient, and the adherend and the pressure-sensitive adhesive It tends to cause blisters generated between the layer and the pressure-sensitive adhesive composition layer. Furthermore, when the amount of the cross-linking agent is large, there is a tendency that the peeling charging characteristics are reduced. These cross-linking agents may be used alone or in combination of two or more.

  Further, as a substantial cross-linking agent, a polyfunctional monomer having two or more radiation-reactive unsaturated bonds may be added and cross-linked by radiation or the like. Examples of the polyfunctional monomer include two or more radiation-reactive unsaturated bonds such as a vinyl group, an acryloyl group, a methacryloyl group, and a vinylbenzyl group which can be cross-linked (cured) by irradiation with radiation. The polyfunctional monomer component is used. Generally, those having 10 or less radiation-reactive unsaturated bonds are preferably used. In addition, the polyfunctional monomers may be used alone or in combination of two or more.

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

  The content of the polyfunctional monomer used in the present invention is appropriately selected depending on the balance with the (meth) acrylic polymer to be crosslinked, and further on the intended use as the pressure-sensitive adhesive sheet. In order to obtain sufficient heat resistance due to the cohesive force of the pressure-sensitive adhesive layer, it is generally preferable that the pressure-sensitive adhesive layer be contained in an amount of 0.1 to 30 parts by mass based on 100 parts by mass of the (meth) acrylic polymer. . Further, from the viewpoint of flexibility and adhesiveness, it is more preferable to mix the compound in an amount of 10 parts by mass or less based on 100 parts by mass of the (meth) acrylic polymer.

  Examples of the radiation include ultraviolet rays, laser rays, α-rays, β-rays, γ-rays, X-rays, and electron beams, and ultraviolet rays are preferably used in terms of good controllability and handleability, and cost. Used. More preferably, ultraviolet light having a wavelength of 200 to 400 nm is used. Ultraviolet rays can be emitted using an appropriate light source such as a high-pressure mercury lamp, a microwave excitation lamp, and a chemical lamp. When ultraviolet rays are used as the radiation, a photopolymerization initiator is added to the pressure-sensitive adhesive composition.

In the case where the photopolymerization initiator is added, the pressure-sensitive adhesive composition is applied directly onto an adherend, or is coated on one or both sides of a support, and then irradiated with light to form a pressure-sensitive adhesive layer. Can be obtained. Usually, the pressure-sensitive adhesive layer is obtained by irradiating ultraviolet rays having an illuminance of 1 to 200 mW / cm ² at a wavelength of 300 to 400 nm to a light amount of about 200 to 4000 mJ / cm ² to carry out photopolymerization.

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

  Examples of the photoradical polymerization initiator include benzoins such as benzoin, benzoin methyl ether, benzoin ethyl ether, methyl o-benzoylbenzoate-p-benzoin ethyl ether, benzoin isopropyl ether, α-methyl benzoin, benzyl dimethyl ketal, and trichloro. Acetophenones such as acetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, and pro-types such as 2-hydroxy-2-methylpropiophenone and 2-hydroxy-4′-isopropyl-2-methylpropiophenone Benzophenones such as piophenones, benzophenone, methylbenzophenone, p-chlorobenzophenone, p-dimethylaminobenzophenone, 2-chlorothioxanthone, 2-chlorothioxanthone Thioxanthones such as tylthioxanthone and 2-isopropylthioxanthone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl) Acylphosphine oxides such as-(ethoxy) -phenylphosphine oxide; benzyl, dibenzosuberone, α-acyl oxime esters and the like.

  As the cationic photopolymerization initiator, for example, onium salts such as aromatic diazonium salt, aromatic iodonium salt, aromatic sulfonium salt, and organic metal complexes such as iron-allene complex, titanocene complex, and arylsilanol-aluminum complex; Examples thereof include nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenolsulfonic acid ester, diazonaphthoquinone, and N-hydroxyimidosulfonate. The above photopolymerization initiators may be used alone or in combination of two or more.

  The photopolymerization initiator is preferably contained in an amount of usually 0.1 to 10 parts by mass, more preferably 0.2 to 7 parts by mass, based on 100 parts by mass of the (meth) acrylic polymer.

  Further, it is also possible to use a photoinitiated polymerization aid such as amines in combination. Examples of the photoinitiating aid include 2-dimethylaminoethylbenzoate, dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, and the like. The photopolymerization initiation aids may be used alone or as a mixture of two or more. The polymerization initiation aid is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 7 parts by mass, based on 100 parts by mass of the (meth) acrylic polymer.

  The pressure-sensitive adhesive composition may further contain a crosslinking catalyst for causing any of the above-mentioned crosslinking reactions to proceed more effectively. Examples of such a crosslinking catalyst include tin catalysts such as dibutyltin dilaurate and dioctyltin dilaurate; tris (acetylacetonato) iron; tris (hexane-2,4-dionato) iron; and tris (heptane-2,4-dionato). Iron, tris (heptane-3,5-dionato) iron, tris (5-methylhexane-2,4-dionato) iron, tris (octane-2,4-dionato) iron, tris (6-methylheptane-2, iron) 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 (hexafluoroacetylacetonato) iron, tris (ethyl acetoacetate) iron, tris (acetoacetate-n-propyl) iron, tris (isopropylacetoacetate) iron, tris (acetoacetate-n-butyl) iron Tris (acetoacetate-sec-butyl) iron, tris (acetoacetate-tert-butyl) iron, tris (methyl propionyl acetate) iron, tris (ethyl propionyl acetate) iron, tris (propionyl acetate-n-propyl) iron, Tris (isopropylionpropionylacetate) iron, tris (propionylacetate-n-butyl) iron, tris (propionylacetate-sec-butyl) iron, tris (propionylacetate-tert-butyl) iron, tris (benzylacetoacetate) iron, tris (Dimethyl malonate) iron, tris (diethyl malonate) iron, trimethoxyiron, Iron-based catalysts such as iron ethoxy, triisopropoxy, and ferric chloride can be used. One of these crosslinking catalysts may be used alone, or two or more thereof may be used in combination.

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

  The pressure-sensitive adhesive composition is further cross-linked to suppress excessive viscosity increase and gelation of the pressure-sensitive adhesive composition after blending any of the cross-linking agents described above, and to extend the pot life of the pressure-sensitive adhesive composition. A retarder can be included. Examples of such a crosslinking retarder include β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, and stearyl acetoacetate; and acetylacetone, 2,4-hexanedione and benzoylacetone. Keto-enol tautomers such as β-diketone are exemplified. In particular, acetylacetone or ethyl acetoacetate is preferably used as a crosslinking retarder. The content of the crosslinking retarder is preferably 1 to 30 parts by mass based on 100 parts by mass of the (meth) acrylic polymer.

  Further, the pressure-sensitive adhesive composition may contain other known additives, for example, colorants, powders such as pigments, surfactants, plasticizers, tackifiers, low molecular weight 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, etc. Can be added as appropriate according to the intended use.

<Adhesive layer / Adhesive sheet>

  The pressure-sensitive adhesive sheet of the present invention preferably has a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition formed on one or both surfaces of a support. The pressure-sensitive adhesive sheet disclosed herein is generally in a form called a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive film, or the like, and is particularly used as an optical component (for example, a liquid crystal display panel component such as a polarizing plate or a wave plate). It is suitable as a surface protection film for protecting the surface of the optical component during processing or transporting the optical component. The pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet is typically formed continuously, but is not limited to such a form.For example, a pressure-sensitive adhesive formed in a regular or random pattern such as a dot shape, a stripe shape, or the like. It may be an agent layer. Further, the pressure-sensitive adhesive sheet disclosed herein may be in a roll shape or a sheet-like shape.

  The pressure-sensitive adhesive sheet of the present invention is preferably formed by forming the pressure-sensitive adhesive layer on a support (substrate). In this case, the cross-linking of the pressure-sensitive adhesive composition is preferably performed after the application of the pressure-sensitive adhesive composition. Generally, it is also possible to transfer a pressure-sensitive adhesive layer comprising a cross-linked pressure-sensitive adhesive composition to a support or the like.

  The method for forming the pressure-sensitive adhesive layer on the support is not particularly limited. For example, the pressure-sensitive adhesive composition (solution) is applied to the support, and the polymerization solvent and the like are dried and removed to form the pressure-sensitive adhesive layer on the support. It is produced by forming on. Thereafter, curing may be performed for the purpose of adjusting the migration of components of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. When the pressure-sensitive adhesive composition is coated on a support to form 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 coated on the support. May be added.

  In addition, as a method for forming the pressure-sensitive adhesive layer at the time of producing the pressure-sensitive adhesive sheet (surface protective film) of the present invention, a known method used for producing pressure-sensitive adhesive tapes is used. Specific examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, and extrusion coating using a die coater.

  The pressure-sensitive adhesive sheet of the present invention is usually prepared so that the pressure-sensitive adhesive layer has a thickness of 3 to 100 μm, preferably about 5 to 50 μm. It is preferable that the thickness of the pressure-sensitive adhesive layer be within the above-mentioned range since a proper balance between removability and adhesiveness can be easily obtained.

  Further, the adhesive sheet of the present invention preferably has a total thickness of 1 to 400 μm, more preferably 10 to 200 μm, and most preferably 20 to 100 μm. When the content is within the above range, the adhesive properties (removability, adhesiveness, etc.), workability, and appearance properties are excellent, which is a preferable embodiment. In addition, the total thickness means the total thickness including all of these layers when a support, a pressure-sensitive adhesive layer, and other components such as an antistatic layer are provided.

<Support>
In the technology disclosed herein, the resin material constituting the support (substrate) can be used without any particular limitation. For example, transparency, mechanical strength, heat stability, moisture shielding property, isotropic It is preferable to use one having excellent properties such as flexibility, flexibility, and dimensional stability. In particular, since the support 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 include polyester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and polybutylene terephthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; polycarbonate polymers; and polymethyl methacrylate. A plastic film composed of a resin material containing an acrylic polymer as a main resin component (a main component of the resin component, typically a component occupying 50% by mass or more) is preferably used as the support. it can. Other examples of the resin material include styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer; olefin-based polymers such as polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, and ethylene-propylene copolymer; Examples of the resin material include vinyl chloride polymers; amide polymers such as nylon 6, nylon 6,6, and aromatic polyamide; and the like. Still other examples of the resin material include an imide polymer, a sulfone polymer, a polyether sulfone polymer, a polyether ether ketone polymer, a polyphenylene sulfide polymer, a vinyl alcohol polymer, a vinylidene chloride polymer, and a vinyl butyral polymer. Allylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and the like. The support may be a blend of two or more of the above-mentioned polymers.

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

  Various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (eg, a pigment or a dye) may be added to the resin material constituting the support, if necessary. The surface of the support may be subjected to a known or commonly used surface treatment such as a corona discharge treatment, a plasma treatment, an ultraviolet irradiation treatment, an acid treatment, an alkali treatment, and the application of a primer. Such a surface treatment may be, for example, a treatment for increasing the adhesion (anchoring property of the pressure-sensitive adhesive layer) between the support and the pressure-sensitive adhesive layer (and, in some cases, an antistatic layer or the like). A surface treatment that introduces a polar group such as a hydroxyl group into the surface of the support can be preferably employed.

  Further, the pressure-sensitive adhesive sheet of the present invention may have an antistatic layer on the surface of the support opposite to the pressure-sensitive adhesive layer side. Further, it is also possible to use a plastic film that has been subjected to an antistatic treatment as the support. The use of the support is preferable because the self-adhesive sheet (surface protective film) itself can be prevented from being charged when peeled off.

  Further, by subjecting the support to an antistatic treatment, it is possible to obtain a pressure-sensitive adhesive sheet having a reduced electrostatic charge and an excellent antistatic property for peeling to an adherend. The method for imparting anti-peeling antistatic property is not particularly limited, and a conventionally known method can be used. For example, an antistatic resin, a conductive polymer, or a conductive substance composed of an antistatic agent and a resin component can be used. A method of applying a conductive resin containing, a method of depositing or plating a conductive substance, a method of kneading an antistatic agent or the like, and the like.

<Separator>
In the pressure-sensitive adhesive sheet 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.

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

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

  The optical member of the present invention is preferably formed by laminating the pressure-sensitive adhesive sheet. Since the pressure-sensitive adhesive sheet is excellent in shearing force at the time of low-speed peeling, curl of the adherend (optical member) to which the pressure-sensitive adhesive sheet is bonded can be suppressed (curl adjusting property), and excellent in handleability. Since it has excellent anti-peeling antistatic properties, it can be used for surface protection applications (surface protection films) at the time of processing, transportation, shipping, etc., and is useful for protecting the surface of the optical member (polarizing plate, etc.). In particular, since it can be used for plastic products that easily generate static electricity, it is very useful for antistatic applications in optical and electronic component-related technical fields where charging is a particularly serious problem.

  Hereinafter, some examples related to the present invention will be described, but it is not intended to limit the present invention to those shown in the specific examples. In the following description, “parts” and “%” are based on mass unless otherwise specified.

  Further, each characteristic in the following description was measured or evaluated as follows.

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

Sample concentration: 0.2% by mass (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column: TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column: TSKgel SuperH-RC (1)
Detector: Differential refractometer (RI)
The weight average molecular weight was determined in terms of polystyrene.

<Glass transition temperature (Tg) of (meth) acrylic polymer>
The glass transition temperature Tg (° C.) was determined by the following equation (17) using the following literature value as the glass transition temperature Tgn (° C.) of the homopolymer of each monomer.

Formula (17): 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
[Wherein 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 values:
2-ethylhexyl acrylate (2EHA): -70 ° C
n-butyl acrylate (BA): -55 ° C
N, N-diethylacrylamide (DEAA): 81 ° C
N, N-dimethylacrylamide (DMAA): 119 ° C
Acryloyl morpholine (ACMO): 145 ° C
Acrylic acid (AA): 106 ° C
Ethoxydiethylene glycol acrylate (EDE): -70 ° 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 Publishing Division), "Polymer Handbook" (John Wiley & Sons), and monomer manufacturer cadagalog values were referred to.

  The glass transition temperature (Tg) (° C.) of a (meth) acrylic polymer obtained from a monomer whose literature value is unknown was determined by dynamic viscoelasticity measurement according to the following procedure.

First, a sheet of a (meth) acrylic polymer having a thickness of 20 μm is laminated to have a thickness of about 2 mm, which is punched into φ7.9 mm to form a cylindrical pellet, and a glass transition temperature (Tg) measurement sample. did.
Using the measurement sample, the measurement sample was fixed to a jig of a φ7.9 mm parallel plate, and the temperature dependence of the loss elastic modulus G ″ was measured using a dynamic viscoelasticity measuring device (ARES, manufactured by Rheometrics). The temperature at which the measured G ″ curve was maximized was taken as the glass transition temperature (Tg) (° C.). The measurement conditions are as follows.
Measurement: Shear mode Temperature range: -70 ° C to 150 ° C
Temperature rise range: 5 ° C / min
Frequency: 1 Hz

<Measurement of peeling voltage>
After the pressure-sensitive adhesive sheet 1 according to the example was cut into a size of 70 mm in width and 130 mm in length and the release liner was peeled off, as shown in FIG. 1, an acrylic plate 10 (made by Mitsubishi Rayon Co., Ltd. On the surface of a polarizing plate 20 (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm) bonded to a product name “Acrylite”, thickness: 1 mm, width: 70 mm, length: 100 mm) The pressure-sensitive adhesive sheet 1 was pressure-bonded with a hand roller such that one end of the pressure-sensitive adhesive sheet 1 protruded 30 mm from the end of the polarizing plate 20.
The sample was left in an environment of 23 ° C. × 50% RH for one day, and then set at a predetermined position on a sample fixing table 30 having a height of 20 mm. The end of the pressure-sensitive adhesive sheet 1 protruding 30 mm from the polarizing plate 20 was fixed to an automatic winding machine (not shown), and peeled at a peeling angle of 150 ° and a peeling speed of 10 m / min. An electric potential measuring device 40 (Kasuga Electric Co., Ltd., model “KSD-0103”) in which the potential of the surface of the adherend (polarizing plate) generated at this time is fixed at a position at a height of 100 mm from the center of the polarizing plate 20. , The peeling voltage was measured. The measurement was performed in an environment of 23 ° C. and 50% RH. In addition, the peeling charge voltage contributes to the peeling antistatic property.

  The peeling voltage (kV) (absolute value) in the present invention is preferably 0.8 or less, more preferably 0.7 or less, and further preferably 0.5 or less. When it is within the above range, the pressure-sensitive adhesive sheet after peeling is not charged, and is excellent in peeling antistatic property and workability, so that it is a preferable embodiment.

<Measurement of shear force>
After the pressure-sensitive adhesive sheet is cut into a size of 10 mm in width and 100 mm in length and the separator is peeled off, a TAC polarizing plate (Nitto Denko Corporation) is set so that the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet becomes 1 cm ^2. , SEG1423DU polarizing plate, width: 25 mm, length: 100 mm), and allowed to stand at room temperature (23 ° C. × 50% RH) for 30 minutes, and then sheared at a peeling rate of 0.06 mm / min (low-speed peeling). And the maximum load (N / cm ² ) at that time was defined as a shearing force.

The shearing force (N / cm ² ) is 10 or more, preferably 10 to 40, and more preferably 10 to 30. If the shearing force is within the above range, it is possible to withstand the force in the shearing direction generated when the adherend attempts to curl, without causing slippage or displacement of the adhesive sheet, curling the adherend. This is preferable because it can be suppressed.

  The method for preparing the (meth) acrylic polymer, the pressure-sensitive adhesive composition (acrylic pressure-sensitive adhesive solution), and the pressure-sensitive adhesive sheet (surface protective film) are described below.

[Example 1]
<Preparation of (meth) acrylic polymer>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 94 parts by mass of 2-ethylhexyl acrylate (2EHA), 1 part by mass of N, N-diethylacrylamide (DEAA), ethoxydiethylene glycol acrylate ( 1 part by mass of EDE), 4 parts by mass of 4-hydroxybutyl acrylate (HBA), 0.2 parts by mass of 2,2′-azobisisobutyronitrile as a polymerization initiator, and 150 parts by mass of ethyl acetate are charged and gently stirred. While introducing a nitrogen gas, the polymerization reaction was carried out for 5 hours while maintaining the liquid temperature in the flask at around 60 ° C. to prepare an acrylic polymer solution (40% by mass). The acrylic polymer had a weight average molecular weight of 570,000 and a glass transition temperature (Tg) of -68 ° C.

<Preparation of acrylic pressure-sensitive adhesive solution>
The acrylic polymer solution (40% by mass) was diluted to 20% by mass with ethyl acetate, and 500 parts by mass (100 parts by mass of solid content) of this solution was diluted with 1-butyl-3-methylpyridinium bis ( Trifluoromethanesulfonyl) imide (BMP) 0.2 parts by mass (solids content 0.2 parts by mass), as a cross-linking agent, isocyanurate of hexamethylene diisocyanate (Coronate HX: C / HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) 2 parts by mass Parts (solids 2 parts by mass), 2 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) (solids 0.02 parts by mass) as a cross-linking catalyst, mixing and stirring are performed, and the acrylic pressure-sensitive adhesive solution is added. Prepared.

<Preparation of antistatic layer solution>
Polyester resin Vironal 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 crosslinking agent Isocyanurate of diisocyanate, oleamide in a mixed solvent of water / ethanol (1/3) as a lubricant, 100 parts by mass of binder in solid content, 75 parts by mass of conductive polymer in solid content, and solid agent of cross-linking 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 mixed well. Thus, an antistatic layer solution of about 0.4% NV was prepared.

<Preparation of support (substrate) with antistatic layer>
The solution for the antistatic layer is dried on a corona-treated surface of 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 having a corona treatment on one side as a support. It was applied so that the thickness afterwards was 30 nm. The coated material was heated at 130 ° C. for 1 minute and dried to prepare a support (substrate) having an antistatic layer having an antistatic layer on one side of the PET film.

<Preparation of adhesive sheet (surface protection film)>
The acrylic pressure-sensitive adhesive solution was applied to the surface of the support (substrate) with the antistatic layer opposite to the antistatic layer, and heated at 130 ° C. for 1 minute to form a 15 μm-thick pressure-sensitive adhesive layer. . Next, a silicone-treated surface of a polyethylene terephthalate film (thickness: 25 μm), which is a separator having one surface subjected to silicone treatment, was bonded to the surface of the pressure-sensitive adhesive layer to prepare a pressure-sensitive adhesive sheet (surface protective film).

[Examples 2 to 7 and Comparative Examples 1 to 3]
An adhesive sheet (surface protective film) was produced in the same manner as in Example 1 based on the content of the composition shown in Table 1. The other additives not blended in Example 1 were blended at the same timing as the antistatic agent. Further, the blending amount in Table 1 indicates a solid content.

  Table 1 shows the results of the various measurements and evaluations described above for the pressure-sensitive adhesive sheets according to the examples and the comparative examples.

The abbreviations in Table 1 are described below.
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate DEAA: N, N-diethylacrylamide DMAA: N, N-dimethylacrylamide ACMO: acryloylmorpholine CHM: N-cyclohexylmaleimide EDE: ethoxydiethylene glycol acrylate PME-400: methoxy Polyethylene glycol monoacrylate (number of moles of EO added: about 9, manufactured by NOF Corporation)
PME-1000: methoxy polyethylene glycol monoacrylate (number of moles of EO added: about 23, manufactured by NOF Corporation)
HBA: 4-hydroxybutyl acrylate AA: Acrylic acid KF355A: Organopolysiloxane having an oxyalkylene chain (HLB value: 12) (trade name: KF-355A, manufactured by Shin-Etsu Chemical Co., Ltd.)
KF353: organopolysiloxane having an oxyalkylene chain (HLB value: 10) (trade name: KF-353, manufactured by Shin-Etsu Chemical Co., Ltd.)
C / HX: Isocyanurate of hexamethylene diisocyanate (trade name: Coronate HX, manufactured by Nippon Polyurethane Co.)
BMP: 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide (ionic liquid, liquid at 25 ° C., Wako Pure Chemical Industries, Ltd.)
OMP: 1-octyl-4-methylpyridinium hexafluorophosphate (ionic liquid, melting point: 44 ° C.)
BP: 1-butylpyridinium hexafluorophosphate (ionic liquid, melting point: 75 ° C, Wako Pure Chemical Industries, Ltd.)
LiTFSI: lithium bis (trifluoromethanesulfonyl) imide (alkali metal salt, Kishida Chemical Co., Ltd.)
25R-1: manufactured by ADEKA Corporation, trade name "Adecapluronic 25R-1" (number average molecular weight 2800, ethylene oxide group content 10% by mass, active ingredient 100% by mass)

  From Table 1, it was confirmed that in all the examples, the shear force at the time of low-speed peeling and the antistatic property of peeling were excellent. On the other hand, in Comparative Example 1, the nitrogen-containing monomer was not used, so that the cohesive force of the pressure-sensitive adhesive was low and the shearing force was poor. In Comparative Example 2, the alkylene oxide group-containing monomer was not used, so the melting point was low. Ion conduction caused by an organic salt at 150 ° C. or lower is hindered, and the anti-peeling property is poor. In Comparative Example 3, the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms is lower than a desired ratio. It was confirmed that the cohesive force of the pressure-sensitive adhesive was reduced and the shearing force was inferior because the compounding was performed and the alkylene oxide group-containing monomer was used in excess.

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

1: Adhesive sheet 10: Acrylic plate 20: Polarizing plate 30: Sample fixing stand 40: Potential measuring device

Claims (4)

As the monomer component, a (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms is 40% by mass or more, a nitrogen-containing monomer is 1 to 5% by mass, and an alkylene oxide group-containing monomer is 0.5 to 40% by mass. % (Meth) acrylic polymer containing no carboxyl group-containing monomer, and an organic salt having a melting point of 150 ° C. or less (excluding an ionic liquid that is a liquid substance at ordinary temperature) and / or an alkali metal salt. A pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition containing the pressure-sensitive adhesive layer on one or both surfaces of the support,
After bonding the adhesive surface of the adhesive layer to the TAC polarizing plate, the adhesive layer was pulled in a shearing direction at a peeling rate of 0.06 mm / min, and the shearing force, which was the maximum load (N / cm ² ) at that time, was 10 N / cm. pressure-sensitive adhesive sheet according to claim ² or der Rukoto. The pressure-sensitive adhesive sheet according to claim 1, wherein the organic salt having a melting point of 150 ° C or less is at least one selected from the group consisting of a nitrogen-containing onium salt, a sulfur-containing onium salt, and a phosphorus-containing onium salt. The pressure-sensitive adhesive sheet according to claim 1, further comprising an alkylene oxide group-containing compound containing no organopolysiloxane having a number average molecular weight of 10,000 or less. An optical member comprising the pressure-sensitive adhesive sheet according to any one of claims 1 to 3 bonded thereto.