WO2018056167A1 - Pressure-sensitive adhesive composition, pressure-sensitive adhesive sheet, and optical member - Google Patents

Abstract

The present invention provides a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet formed using the pressure-sensitive adhesive composition, and an optical member to which the pressure-sensitive adhesive sheet has been applied. The pressure-sensitive adhesive sheet, even after having been applied to an optical member such as a polarizing plate and stored in a high-temperature environment, can achieve the stability over time of antistatic properties and stripping electrification voltage. The pressure-sensitive adhesive composition of the present invention is characterized by comprising a tacky polymer and an ionic-group-containing silicone represented by formula (1). (R₁ to R₄ may be the same or different and each include any of a C_1-10 alkyl group, alkoxy group, aryl group, alicyclic group, fluoroalkyl group, and ionic group, provided that one or more of R₁ to R₄ include an ionic group; and n is an integer of 0-100.)

Description

Adhesive composition, adhesive sheet, and optical member

The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive sheet, and an optical member. In particular, the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition is used for application to a plastic product or the like that is likely to generate static electricity (for example, a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, etc.). Especially, it is used for the purpose of protecting the surface of an optical member (for example, a polarizing plate, a wave plate, a retardation plate, an optical compensation film, a reflection sheet, a brightness enhancement film used for a liquid crystal display). It is useful as a surface protective film.

The surface protective film (also referred to as a surface protective sheet) generally has a configuration in which an adhesive layer is provided on a film-like base film (support). Such a protective film is bonded to an adherend (protected body) through the pressure-sensitive adhesive layer, and is used for the purpose of protecting the adherend from scratches and dirt during processing and transportation. For example, a panel of a liquid crystal display is formed by bonding an optical member such as a polarizing plate or a wave plate to a liquid crystal cell via an adhesive layer. In the manufacture of such a liquid crystal display panel, a polarizing plate to be bonded to a liquid crystal cell is once manufactured in a roll form, and then unwound from this roll and cut into a desired size according to the shape of the liquid crystal cell. . Here, in order to prevent the polarizing plate from being rubbed and scratched with a transport roll or the like in an intermediate step, a measure is taken to attach a surface protective film to one side or both sides (typically, one side) of the polarizing plate. This surface protective film is peeled off and removed when it is no longer needed.

Generally, since the surface protective film and the optical member are made of a plastic material, they have high electrical insulation and generate static electricity due to friction and peeling. For this reason, static electricity tends to be generated even when the surface protective film is peeled off from the optical member such as a polarizing plate, and when voltage is applied to the liquid crystal with this static electricity remaining, the alignment of the liquid crystal molecules is lost, There is also a concern that the panel may be lost. Also, the presence of static electricity can be a factor that attracts dust and reduces workability. Under such circumstances, the surface protection film is subjected to an antistatic treatment. For example, as a surface layer (topcoat layer, back layer) of the surface protection film, an antistatic layer is formed or an antistatic coating is applied. Thus, an antistatic function is provided (see Patent Documents 1 and 2).

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

However, when the pressure-sensitive adhesive layer surface containing the ionic compound is attached to an optical member such as a polarizing plate and stored in a high temperature (warming) environment, the ionic compound penetrates from the surface of the optical member. As a result, the antistatic ability of the ionic compound is lowered, and the optical member cannot be sufficiently protected.

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

Therefore, the present invention has been intensively studied in view of the above circumstances. As a result, even when the optical member such as a polarizing plate is pasted and stored in a high temperature environment, the antistatic property and the stability of the stripping voltage with time are stable. It aims at providing the adhesive composition which can achieve property, the adhesive sheet formed with the said adhesive composition, and the optical member to which the said adhesive sheet is affixed.

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

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

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

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

The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition on at least one surface of a base film, and contains the ionic group inside and / or on the surface of the pressure-sensitive adhesive layer. Preferably silicone is present.

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

In the pressure-sensitive adhesive sheet of the present invention, the ionic group-containing silicone is preferably present on the surface of the separator that contacts the pressure-sensitive adhesive layer.

The optical member of the present invention is preferably attached with the pressure-sensitive adhesive sheet or a pressure-sensitive adhesive sheet obtained by peeling the separator from the pressure-sensitive adhesive sheet.

The present invention uses a pressure-sensitive adhesive composition containing a specific ionic group-containing silicone, so that a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition is used for an optical member such as a polarizing plate. Even when pasted and stored in a high temperature environment, it is useful because it can achieve excellent antistatic properties and stability over time of the stripping voltage.

It is typical sectional drawing which shows one structural example of the adhesive sheet (surface protection film) which concerns on this invention. It is explanatory drawing which shows the measuring method of peeling voltage.

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

<Overall structure of adhesive sheet (surface protective film)>
The pressure-sensitive adhesive sheet disclosed herein is generally in a form referred to as a pressure-sensitive adhesive tape, pressure-sensitive adhesive label, pressure-sensitive adhesive film, etc., and 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 protective film for protecting the surface of the optical component during processing or transport of the optical component. The pressure-sensitive adhesive layer in the surface protective film is typically formed continuously, but is not limited to such a form, and is formed in a regular or random pattern such as a spot or stripe. It may be an adhesive layer. In addition, the surface protective film disclosed herein may be in the form of a roll or a single sheet.

<Base film>
The pressure-sensitive adhesive sheet (surface protective film) of the present invention has a base film. In the technology disclosed herein, the resin material constituting the base film can be used without any particular limitation. For example, transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, It is preferable to use a material excellent in properties such as flexibility and dimensional stability. In particular, since the base film has flexibility, the pressure-sensitive adhesive composition can be applied by a roll coater or the like, and can be wound up into a roll shape, which is useful.

Examples of the substrate film (substrate, 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 A plastic film composed of a resin material having a main resin component (a main component of the resin component, typically a component occupying 50% by mass or more) such as an acrylic polymer such as polymethyl methacrylate; It can be preferably used as the substrate film. Other examples of the resin material include styrene polymers such as polystyrene and acrylonitrile-styrene copolymers; olefin polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, and ethylene-propylene copolymers; Examples of the resin material include vinyl chloride polymers; amide polymers such as nylon 6, nylon 6,6, and aromatic polyamide. Still other examples of the resin material include imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers. , Arylate polymers, polyoxymethylene polymers, epoxy polymers and the like. A base film made of a blend of two or more of the above-described polymers may be used.

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

In the resin material constituting the base film, various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, and a colorant (pigment, dye, etc.) may be blended as necessary. For example, a known or conventional surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of a primer may be performed. Such surface treatment can be, for example, a treatment for improving the adhesion between the base film and the pressure-sensitive adhesive layer (the anchoring property of the pressure-sensitive adhesive layer).

In the pressure-sensitive adhesive sheet (surface protective film) of the present invention, a plastic film subjected to an antistatic treatment can be used as the base film. Use of the substrate film is preferable because charging of the pressure-sensitive adhesive sheet itself when peeled is suppressed. In addition, the base film is a plastic film, and by applying an antistatic treatment to the plastic film, it is possible to reduce the charge of the pressure-sensitive adhesive sheet itself and to have an excellent antistatic ability to the adherend. In addition, there is no restriction | limiting in particular as a method to provide an antistatic function, A conventionally well-known method can be used, for example, antistatic resin which consists of an antistatic agent and a resin component, a conductive polymer, and a conductive substance. Examples thereof include a method of applying a conductive resin, a method of depositing or plating a conductive material, a method of kneading an antistatic agent, and the like.

The thickness of the substrate film is usually about 5 to 200 μm, preferably about 10 to 100 μm. When the thickness of the base film is within the above range, it is preferable because the workability for bonding to the adherend and the workability for peeling from the adherend are excellent.

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

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

When the pressure-sensitive adhesive layer uses an acrylic pressure-sensitive adhesive, the (meth) acrylic polymer, which is a pressure-sensitive polymer constituting the acrylic pressure-sensitive adhesive, is an alkyl having 1 to 14 carbon atoms as a raw material monomer constituting the pressure-sensitive adhesive layer. A (meth) acrylic monomer having a group can be used as the main monomer. As said (meth) acrylic-type monomer, 1 type (s) or 2 or more types can be used. By using the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, it becomes easy to control the peeling force (adhesive strength) to the adherend (protected body) to be low and light peeling. A pressure-sensitive adhesive sheet (surface protective film) having excellent properties and removability can be obtained. In the present invention, the (meth) acrylic polymer refers to an acrylic polymer and / or a methacrylic polymer, and the (meth) acrylate refers to acrylate and / or methacrylate.

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

In particular, in the case of a surface protective film as the pressure-sensitive adhesive sheet of the present invention, n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl ( (Meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n- Suitable examples include (meth) acrylic monomers having an alkyl group having 4 to 14 carbon atoms such as tetradecyl (meth) acrylate. In particular, by using a (meth) acrylic monomer having an alkyl group having 4 to 14 carbon atoms, it becomes easy to control the peel strength (adhesive strength) to the adherend low and has excellent removability. It becomes.

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

In the pressure-sensitive adhesive composition of the present invention, the (meth) acrylic polymer preferably contains a hydroxyl group-containing (meth) acrylic monomer as a raw material monomer. As said hydroxyl group containing (meth) acrylic-type monomer, 1 type (s) or 2 or more types can be used. By using the hydroxyl group-containing (meth) acrylic monomer, it becomes easy to control the crosslinking of the pressure-sensitive adhesive composition, and as a result, balance between improvement of wettability by flow and reduction of peeling force (adhesive strength) in peeling. It becomes easier to control. Furthermore, unlike carboxyl groups and sulfonate groups that can generally act as cross-linking sites, hydroxyl groups have moderate interactions with ionic group-containing silicones, which are antistatic components (antistatic agents), and oxyalkylene group-containing compounds. Therefore, it can be suitably used also in terms of antistatic properties.

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

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

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

As the polymerizable monomer other than the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms used in the (meth) acrylic polymer, and the hydroxyl group-containing (meth) acrylic monomer, A carboxyl group-containing (meth) acrylic monomer can be used. By using the carboxyl group-containing (meth) acrylic monomer, the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) can suppress an increase in the adhesive strength over time, re-peelability, adhesive strength increase prevention, and workability In addition, the cohesive force of the pressure-sensitive adhesive layer and the shearing force are excellent, which is preferable.

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

The carboxyl group-containing (meth) acrylic monomer is preferably 0 to 5% by mass and preferably 0 to 3% by mass with respect to 100% by mass of the total amount of monomer components constituting the (meth) acrylic polymer. More preferably, it is 0 to 2% by mass, still more preferably 0 to 0.19% by mass. When the amount exceeds 5% by mass, a large number of acid functional groups such as carboxyl groups having a large polar action are present, and when an ionic group-containing silicone or an oxyalkylene group-containing compound as an antistatic component is blended, the antistatic component For example, the interaction of an acid functional group such as a carboxyl group is not preferable because ionic conduction is hindered, conductivity efficiency is lowered, and sufficient antistatic properties may not be obtained.

When the hydroxyl group-containing (meth) acrylic monomer and the carboxyl group-containing (meth) acrylic monomer are used in combination, the total amount of monomer components constituting the (meth) acrylic polymer is 100% by mass. The carboxyl group-containing (meth) acrylic monomer is preferably contained in an amount of 0.01 to 0.19% by mass. By adjusting within the above range, a pressure-sensitive adhesive composition excellent in re-peelability and anti-adhesiveness-preventing property can be obtained while maintaining the antistatic property, which is effective.

Further, the (meth) acrylic monomer having an alkyl group having 1 to 14 carbon atoms, the hydroxyl group-containing (meth) acrylic monomer, and the carboxyl group-containing (meth) acrylic used in the (meth) acrylic polymer. Any other polymerizable monomer other than the monomer can be used without particular limitation as long as it does not impair the characteristics of the present invention. For example, cohesive strength / heat resistance improving components such as cyano group-containing monomers, vinyl ester monomers, aromatic vinyl monomers, amide group-containing monomers, imide group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, N-acryloylmorpholine In addition, a component having a functional group functioning as an improvement in peeling strength (adhesive strength) such as a vinyl ether monomer or as a crosslinking base point can be appropriately used. Among them, it is preferable to use a nitrogen-containing monomer such as a cyano group-containing monomer, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, and N-acryloylmorpholine. Use of a nitrogen-containing monomer is useful because it can secure an appropriate peeling force (adhesive strength) that does not cause floating or peeling, and can provide a pressure-sensitive adhesive sheet (surface protective film) excellent in shearing force. . These polymerizable monomers can be used alone or in combination of two or more.

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

Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, and N, N-diethyl. Examples include methacrylamide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, and diacetone acrylamide.

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

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

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

Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethyl styrene, α-methyl styrene, and other substituted styrene.

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, isobutyl vinyl ether, and the like.

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

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

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

The alkylene oxide group-containing reactive monomer may be used alone or in combination of two or more, but the total content is the total amount of monomer components of the (meth) acrylic polymer. Among these, 0 to 20% by mass is preferable, and 0 to 10% by mass is more preferable. If the content of the alkylene oxide group-containing reactive monomer exceeds 20% by mass, the interaction with the ionic group-containing silicone and the oxyalkylene group-containing compound is increased, ionic conduction is hindered, and antistatic properties are reduced. This is not preferable.

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

It is more preferable that the alkylene oxide group-containing reactive monomer is a reactive monomer having an ethylene oxide group. By using a reactive monomer-containing (meth) acrylic polymer having an ethylene oxide group as a base polymer, the compatibility between the base polymer and the ionic group-containing silicone or oxyalkylene group-containing compound is improved, and the adherence to the adherend is improved. Bleed is suitably suppressed, and a low-staining adhesive composition is obtained.

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

Specific examples of the (meth) acrylic acid alkylene oxide adduct include, for example, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, polyethylene glycol-polybutylene glycol (meth) ) Acrylate, polypropylene glycol-polybutylene glycol (meth) acrylate, 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.

Specific examples of the reactive surfactant include, for example, an anionic reactive surfactant having a (meth) acryloyl group or an allyl group, a nonionic reactive surfactant, and a cationic reactive surfactant. Can be given.

The (meth) acrylic polymer preferably has a weight average molecular weight (Mw) of 100,000 to 5,000,000, more preferably 200,000 to 4,000,000, still more preferably 300,000 to 3,000,000, and most preferably 300,000 to 950,000. It is. When the weight average molecular weight is smaller than 100,000, the adhesive force tends to be generated due to the reduced cohesive force of the pressure-sensitive adhesive layer. On the other hand, when the weight average molecular weight exceeds 5 million, the fluidity of the polymer is lowered, and the wettability to the adherend (for example, polarizing plate) becomes insufficient, and the adherend and the adhesive sheet (surface protective film) There is a tendency to cause blisters generated between the pressure-sensitive adhesive layer. In addition, a weight average molecular weight means what was obtained by measuring by GPC (gel permeation chromatography).

Further, the glass transition temperature (Tg) of the (meth) acrylic polymer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower (usually −100 ° C. or higher). When the glass transition temperature is higher than 0 ° C., the polymer hardly flows, for example, the wettability to the polarizing plate which is an optical member becomes insufficient, and between the polarizing plate and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (surface protective film). There is a tendency to cause blisters to occur. In particular, when the glass transition temperature is −61 ° C. or lower, an adhesive layer excellent in wettability to a polarizing plate and light release properties can be easily obtained. In addition, the glass transition temperature of a (meth) acrylic-type polymer can be adjusted in the said range by changing the monomer component and composition ratio to be used suitably.

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

Any appropriate urethane-based pressure-sensitive adhesive can be adopted when a urethane-based pressure-sensitive adhesive is used for the pressure-sensitive adhesive layer. As such a urethane type adhesive, Preferably, what consists of a urethane type polymer which is an adhesive polymer obtained by making a polyol and a polyisocyanate compound react is mentioned. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, and the like.

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

Further, examples of the silicone pressure-sensitive adhesive include addition reaction curable silicone pressure-sensitive adhesives and peroxide curable silicone pressure-sensitive adhesives. Among these silicone pressure-sensitive adhesives, peroxides (benzoyl peroxide and the like) are not used, and decomposition products are not generated. Therefore, an addition reaction curable silicone pressure-sensitive adhesive is preferable.

As the curing reaction of the addition reaction curable silicone pressure-sensitive adhesive, for example, when obtaining a polyalkyl silicone pressure-sensitive adhesive, generally, a method of curing a polyalkylhydrogensiloxane composition with a platinum catalyst can be mentioned.

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

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

Further, the ionic group contained in one or more of R ₁ to R ₄ is preferably an ionic group having an ammonium cation group or a phosphonium cation group. Among them, one or more of R ₁ to R ₄ are preferably composed of a cation structure and an anion component represented by the following formula (a) or (b), or represented by (c) or (d) The zwitterionic structure is preferred.

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

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

On the other hand, the anion component is not particularly limited. For example, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , C ₄ F ₉ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (C ₄ F ₉ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) _n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF _{^{3 CO) N -, C 9}} H 19 COO -, (CH 3) _{^{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.

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

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

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

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

The content of the ionic group-containing silicone is 100 parts by mass of an adhesive polymer (main polymer, for example, (meth) acrylic polymer, urethane polymer, silicone polymer, etc.) constituting the pressure-sensitive adhesive composition. On the other hand, it is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 7.5 parts by mass, still more preferably 0.03 to 5.5 parts by mass, and most preferably 0.04 to 4. 8 parts by mass. Within the above range, even when the pressure-sensitive adhesive sheet of the present invention is affixed to an optical member or the like and stored in a high-temperature environment, the antistatic property, the stability of the stripping voltage over time, and the light release property (re-use (Peelability) can be satisfied, which is preferable. In order to satisfy stain resistance, the amount is preferably 0.01 to 5.5 parts by mass with respect to 100 parts by mass of the adhesive polymer.

<Oxyalkylene group-containing compound>
The pressure-sensitive adhesive composition of the present invention preferably contains an oxyalkylene group-containing compound, more preferably contains an organopolysiloxane having an oxyalkylene chain, and contains an organopolysiloxane having an oxyalkylene main chain. More preferably. By using the organopolysiloxane, it is presumed that the surface free energy on the surface of the pressure-sensitive adhesive is reduced and light release is realized.

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

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

As the organopolysiloxane, those having a siloxane-containing site (siloxane site) as the main chain and an oxyalkylene chain bonded to the end of the main chain are used. By using the organosiloxane having the oxyalkylene chain, it is presumed that the compatibility with the (meth) acrylic polymer and the antistatic component is balanced and light release is realized.

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

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

Furthermore, the end of the oxyalkylene chain may be an alkoxy group or a hydroxyl group, but more preferably an alkoxy group. When a separator is bonded to the surface of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface, an organopolysiloxane having a hydroxyl group at the end causes an interaction with the separator, and adhesion (peeling) occurs when the separator is peeled off from the surface of the pressure-sensitive adhesive layer. The power may increase.

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 and a preferred embodiment is obtained. Furthermore, you may have reactive substituents, such as a (meth) acryloyl group, an allyl group, and a hydroxyl group, in a molecule | numerator. The organopolysiloxane may be used alone or in combination of two or more.

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

In addition to the above-described organosiloxane having (bonding) an oxyalkylene chain, it is also possible to use an organosiloxane having (bonding) an oxyalkylene chain in the side chain. It is more preferable to use an organosiloxane having an oxyalkylene chain. As the organopolysiloxane, a known organopolysiloxane having a polyoxyalkylene side chain can be used as appropriate, and is preferably represented by the following formula (3).

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

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

Specific examples of the organosiloxane having an oxyalkylene chain in the side chain include, for example, trade names KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF as commercially available products. -945, KF-640, KF-642, KF-643, KF-6022, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017, X-22 -2516 (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 (above, Toray Manufactured by Uconing), TSF-4440, TSF-4441, TSF-4445, TSF-4450, TSF-4446, TSF-4442, TSF-4460 (manufactured by Momentive Performance Materials), BYK-333, BYK-307, Examples include BYK-377, BYK-UV3500, BYK-UV3570 (manufactured by Big Chemie Japan). These compounds may be used alone or in combination of two or more.

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

The pressure-sensitive adhesive composition may contain an oxyalkylene group-containing compound that does not contain organopolysiloxane. By containing the said compound in an adhesive, the adhesive which was further excellent in the wettability to a to-be-adhered body can be obtained.

Specific examples of the oxyalkylene group-containing compound not containing the organopolysiloxane include, for example, polyoxyalkylene alkylamine, polyoxyalkylene diamine, polyoxyalkylene fatty acid ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene alkyl phenyl ether. , Nonionic surfactants such as polyoxyalkylene alkyl ether, polyoxyalkylene alkyl allyl ether, polyoxyalkylene alkyl phenyl allyl ether; polyoxyalkylene alkyl ether sulfate ester salt, polyoxyalkylene alkyl ether phosphate ester salt, Oxyalkylene alkylphenyl ether sulfate ester salt, polyoxyalkylene alkylphenyl ether phosphate Anionic surfactants such as salt of salts; other cationic surfactants having polyoxyalkylene chains (polyalkylene oxide chains), amphoteric surfactants, polyether compounds having polyoxyalkylene chains (and their Derivatives), acrylic compounds having a polyoxyalkylene chain (and derivatives thereof), and the like. Moreover, you may mix | blend a polyoxyalkylene chain containing monomer as a polyoxyalkylene chain containing compound. Such polyoxyalkylene chain-containing compounds may be used alone or in combination of two or more.

Specific examples of the polyether compound (polyether component) having a polyoxyalkylene chain include a block copolymer of polypropylene glycol (PPG) -polyethylene glycol (PEG), a block copolymer of PPG-PEG-PPG, Examples thereof include a block copolymer of PEG-PPG-PEG. Examples of the derivative of the polyether compound having a polyoxyalkylene chain include an oxypropylene group-containing compound (PPG monoalkyl ether, PEG-PPG monoalkyl ether, etc.) whose terminal is etherified, and oxypropylene whose terminal is acetylated Group-containing compounds (terminal acetylated PPG and the like), and the like.

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

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

Further, as the monomer unit (component), other monomer units (components) other than the (meth) acrylic acid alkylene oxide can also be used. Specific examples of other monomer components include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) ) Acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) ) Acrylates, isodecyl (meth) acrylates, n-dodecyl (meth) acrylates, n-tridecyl (meth) acrylates, n-tetradecyl (meth) acrylates and other acrylates and / or methacrylates having an alkyl group of 1 to 14 carbon atoms And the like.

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

In a more preferred embodiment, the polyoxyalkylene chain-containing compound not containing the organopolysiloxane is a compound having at least a part of a (poly) ethylene oxide chain. 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. It is done. In particular, when a PPG-PEG-PPG block copolymer is used, a pressure-sensitive adhesive excellent in low contamination can be obtained. As the polyethylene oxide chain-containing compound, the mass of the (poly) ethylene oxide chain in the entire polyoxyalkylene chain-containing compound not containing the organopolysiloxane is preferably 5 to 90% by mass, more preferably 5 to 85%. % By weight, more preferably 5 to 80% by weight, most preferably 5 to 75% by weight.

The molecular weight of the polyoxyalkylene chain-containing compound not containing the organopolysiloxane is suitably a number average molecular weight (Mn) of 50,000 or less, preferably 200 to 30,000, more preferably 200 to 10,000, 200 to 5000 is preferably used. When Mn is larger than 50000, the compatibility with the acrylic polymer is lowered and the pressure-sensitive adhesive layer tends to be whitened. If Mn is less than 200, contamination with the polyoxyalkylene compound may easily occur. In addition, Mn means the value of polystyrene conversion obtained by GPC (gel permeation chromatography) here.

Specific examples of commercially available polyoxyalkylene chain-containing compounds that do not contain the organopolysiloxane include, for example, Adekapluronic 17R-4, Adekapluronic 25R-2 (all of which are manufactured by ADEKA), Latem PD- 420, Latemul PD-420, Latemul PD-450, Emulgen 120 (manufactured by Kao), Aqualon HS-10, KH-10, Neugen EA-87, EA-137, EA-157, EA-167, EA-177 ( As mentioned above, Daiichi Kogyo Seiyaku Co., Ltd.) can be mentioned.

The content of the oxyalkylene group-containing compound is 100 parts by mass of an adhesive polymer (main polymer such as (meth) acrylic polymer, urethane polymer, silicone polymer, etc.) constituting the pressure-sensitive adhesive composition. Is preferably 0.01 to 5.0 parts by mass, more preferably 0.02 to 2 parts by mass, still more preferably 0.03 to 1.6 parts by mass, and most preferably 0.1 to 0. 8 parts by mass. Within the above range, the antistatic property and light releasability (removability) of the pressure-sensitive adhesive sheet of the present invention can be easily achieved, which is preferable.

<Crosslinking agent>
In the pressure-sensitive adhesive sheet (surface protective film) of the present invention, the pressure-sensitive adhesive composition preferably contains a crosslinking agent. Moreover, in this invention, it can be set as an adhesive layer using the said adhesive composition. For example, in the case where the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive containing the (meth) acrylic polymer, the constitutional unit, the structural ratio, the selection and addition ratio of the cross-linking agent, etc. are appropriately determined. By adjusting and crosslinking, a pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer) having more excellent heat resistance can be obtained.

As the cross-linking agent used in the present invention, an isocyanate compound, an epoxy compound, a melamine resin, an aziridine derivative, a metal chelate compound, or the like may be used. In particular, the use of an isocyanate compound is a preferred embodiment. Moreover, these compounds may be used independently and may be used in mixture of 2 or more types.

Examples of the isocyanate compounds include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), dimer acid diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1, Alicyclic isocyanates such as 3-bis (isocyanatomethyl) cyclohexane, aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate (XDI), and the isocyanate compound Allophanate bond, biuret bond, isocyanurate bond, uretdione bond, urea bond, carbodiimide bond Uretonimine bond, polyisocynate modified products thereof obtained by modifying the like oxadiazinetrione bond. For example, as commercial products, the product names Takenate 300S, Takenate 500, Takenate 600, Takenate D165N, Takenate D178N (above, manufactured by Takeda Pharmaceutical Company Limited), Sumijoule T80, Sumijoule L, Death Module N3400 (above, Sumika Bayer Urethane) Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like. These isocyanate compounds may be used alone, or may be used in combination of two or more, and a bifunctional isocyanate compound and a trifunctional or higher isocyanate compound may be used in combination. By using a cross-linking agent in combination, it is possible to achieve both stickiness and resilience (adhesiveness to a curved surface), and a pressure-sensitive adhesive sheet with better adhesion reliability can be obtained.

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

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

Examples of the melamine resin include hexamethylol melamine. Examples of the aziridine derivative include commercially available product names HDU, TAZM, TAZO (manufactured by Mutual Yakugyo Co., Ltd.) and the like.

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

The content of the crosslinking agent used in the present invention is, for example, preferably 0.01 to 20 parts by mass, and 0.1 to 15 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. More preferred is 0.5 to 10 parts by mass, still more preferred is 1 to 6 parts by mass. When the content is less than 0.01 parts by mass, the crosslinking formation by the crosslinking agent becomes insufficient, the cohesive force of the resulting pressure-sensitive adhesive layer becomes small, and sufficient heat resistance may not be obtained, It tends to cause glue residue. On the other hand, when the content exceeds 20 parts by mass, the cohesive force of the polymer is large, the fluidity is lowered, and the wettability to the adherend (for example, polarizing plate) becomes insufficient, and the adherend and the pressure-sensitive adhesive. There is a tendency to cause blisters generated between the layer (adhesive composition layer). Furthermore, when the amount of the crosslinking agent is large, the peeling charging property tends to be lowered. These crosslinking agents may be used alone or in combination of two or more.

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

The content of the crosslinking catalyst is not particularly limited, but is preferably about 0.0001 to 1 part by mass, for example, 0.001 to 0.5 part with respect to 100 parts by mass of the (meth) acrylic polymer. Part by mass is more preferable. Within the above range, when the pressure-sensitive adhesive layer is formed, the speed of the cross-linking reaction is high, and the pot life of the pressure-sensitive adhesive composition is lengthened.

Furthermore, the pressure-sensitive adhesive composition may contain a compound that causes keto-enol tautomerism. For example, in a pressure-sensitive adhesive composition containing a cross-linking agent or a pressure-sensitive adhesive composition that can be used by blending a cross-linking agent, an embodiment including a compound that causes the keto-enol tautomerism can be preferably employed. Thereby, the excessive viscosity raise and gelation of an adhesive composition after a crosslinking agent mixing | blending can be suppressed, and the effect of extending the pot life of an adhesive composition may be implement | achieved. When at least an isocyanate compound is used as the crosslinking agent, it is particularly meaningful to contain a compound that causes keto-enol tautomerism. This technique can be preferably applied when, for example, the pressure-sensitive adhesive composition is in an organic solvent solution or a solvent-free form.

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

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

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

<Adhesive layer and adhesive sheet (surface protective film)>
The pressure-sensitive adhesive sheet of the present invention is formed by forming the pressure-sensitive adhesive layer on at least one surface of a substrate film. In this case, the pressure-sensitive adhesive composition is generally crosslinked after the pressure-sensitive adhesive composition is applied. As a matter of course, it is also possible to transfer a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition after crosslinking to a substrate film or the like.

The method for forming the pressure-sensitive adhesive layer on the base film is not particularly limited. For example, the pressure-sensitive adhesive layer is formed by applying the pressure-sensitive adhesive composition (solution) to the base film and removing the polymerization solvent by drying. It is produced by forming on a base film. Thereafter, curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. In addition, when the pressure-sensitive adhesive composition is applied on the base film to prepare a pressure-sensitive adhesive sheet, the pressure-sensitive adhesive composition includes at least one solvent other than the polymerization solvent so that the pressure-sensitive adhesive composition can be uniformly applied onto the base film. May be newly added.

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

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

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

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

The material constituting the separator includes paper and plastic film, but 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. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer Examples thereof 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 since it is excellent in workability for bonding to the pressure-sensitive adhesive layer and workability for peeling from the pressure-sensitive adhesive layer. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as.

In the pressure-sensitive adhesive sheet of the present invention, the ionic group-containing silicone is preferably present (applied) on the surface of the separator that contacts the pressure-sensitive adhesive layer (see FIG. 1). When the separator is attached to the pressure-sensitive adhesive layer due to the presence of the ionic group-containing silicone on the surface of the separator that contacts the pressure-sensitive adhesive layer (applied or forming a coating film) In addition, the ionic group-containing silicone is transferred (transferred) from the separator surface to the pressure-sensitive adhesive layer surface, and the pressure-sensitive adhesive layer is attached to the surface of the adherend (for example, a polarizing plate) in a high-temperature environment. Even when stored, the ionic group-containing silicone does not penetrate into the adherend (from the surface of the adherend to the inside of the adherend), and the release charging characteristics are stable over time, and antistatic performance over a long period of time. Is maintained, which is a preferred embodiment.

<Optical member>
The optical member of the present invention is preferably pasted (protected) by the pressure-sensitive adhesive sheet. Since the pressure-sensitive adhesive sheet is excellent in antistatic properties and stability over time of the stripping voltage, it can be used for surface protection applications (surface protection film) during processing, transportation, shipment, etc. It is useful for protecting the surface. In particular, since it can be used for plastic products and the like that are likely to generate static electricity, it is very useful for antistatic applications in the technical fields related to optical and electronic parts where charging is a particularly serious problem.

Hereinafter, some examples related to the present invention will be described. However, the present invention is not intended to be limited to the specific examples. In the following description, “part” and “%” are based on mass unless otherwise specified. Further, the blending amount (addition amount) in the table is shown.

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

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

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

<Measurement of 70 ° C storage peeling voltage>
The pressure-sensitive adhesive sheet according to each example was cut to a size of 70 mm in width and 130 mm in length, the release liner was peeled off, and then bonded to a glass plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length) : 100 mm) was pressure-bonded with a hand roller so that one end of the pressure-sensitive adhesive sheet protruded 30 mm from the end of the polarizing plate.
After leaving this sample in an environment of 70 ° C. for 120 hours, as shown in FIG. 2, it was set at a predetermined position on a sample fixing base 30 having a height of 20 mm. The end of the pressure-sensitive adhesive sheet (surface protective film) 1 that protruded 30 mm from the polarizing plate 20 was fixed to an automatic winder (not shown), and was peeled so that the peeling angle was 150 ° and the peeling speed was 30 m / min. The potential measuring device 40 (model “STATIRON DZ-4”, manufactured by Sicid Electrostatic Co., Ltd.) in which the potential of the adherend (polarizing plate) surface generated at this time is fixed at a position 30 mm in height from the center of the polarizing plate 20. ), “70 ° C. storage peeling voltage” was measured. The measurement was performed in an environment of 23 ° C. and 50% RH.

In addition, as an initial peeling band voltage and 70 degreeC preservation | save peeling voltage (kV) (absolute value) in this invention, Preferably it is 0.55 or less, More preferably, it is 0.5 or less, Furthermore, Preferably, it is 0.45 or less. Within the above range, the pressure-sensitive adhesive sheet peeled off at the initial stage and after storage at 70 ° C. for 120 hours is not charged, is excellent in antistatic properties and peeling charging characteristics over time, and is excellent in workability. .

<Presence of contamination (contamination resistance)>
After the pressure-sensitive adhesive sheet according to each example was cut to a size of 50 mm in width and 80 mm in length and the separator was peeled off, bubbles were formed in the TAC polarizing plate (manufactured by Nitto Denko Corporation, SEG1423DU polarizing plate, width: 70 mm, length: 100 mm). While being put, it was pressure-bonded with a hand roller to prepare an evaluation sample. The evaluation sample was allowed to stand in an environment of 70 ° C. for 120 hours, and then the pressure-sensitive adhesive sheet was peeled off from the adherend by hand, and the bubble marks on the adherend surface at that time were visually observed. In the evaluation, a case where no bubble trace was observed was marked as ◯, and a case where a bubble trace was recognized was marked as x.

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

<Preparation of acrylic polymer (2)>
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 91 parts by mass of 2-ethylhexyl acrylate (2EHA), 9 parts by mass of 4-hydroxybutyl acrylate (4HBA), acrylic acid (AA) 0.02 parts by mass, 0.22 parts by mass of 2,2′-azobisisobutyronitrile as a polymerization initiator and 150 parts by mass of ethyl acetate were introduced, nitrogen gas was introduced while gently stirring, and the liquid in the flask A polymerization reaction was carried out for 6 hours while maintaining the temperature at around 65 ° C. to prepare an acrylic polymer (2) solution (40 mass%). The acrylic polymer (2) had a weight average molecular weight (Mw) of 540,000.

<Example 1>
[Preparation of acrylic adhesive solution]
The acrylic polymer (1) solution (40% by mass) is diluted with ethyl acetate to 20% by mass, and ionic group-containing silicone (X-40-2450, 5 parts by weight (manufactured by Shin-Etsu Chemical Co., Ltd.) diluted to 10% with ethyl acetate (solid content 0.5 parts by weight), and isocyanurate of hexamethylene diisocyanate, a trifunctional isocyanate compound (made by Tosoh Corporation) as a crosslinking agent , Coronate HX) 2 parts by mass (solid content 2 parts by mass), 3 parts by mass of dibutyltin dilaurate (1% by mass ethyl acetate solution) (solid content 0.03 parts by mass) as a crosslinking catalyst, mixed and stirred, An acrylic pressure-sensitive adhesive solution was prepared.

[Preparation of antistatic film]
Antistatic by diluting 10 parts by weight of antistatic agent (manufactured by Solvex, Microsolver RMd-142, mainly composed of tin oxide and polyester resin) with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol An agent solution was prepared.
The obtained antistatic agent solution was applied onto a polyethylene terephthalate (PET) film (thickness: 38 μm) using a Meyer bar and dried at 130 ° C. for 1 minute to remove the solvent and remove the antistatic layer (thickness). Thickness: 0.2 μm) to form an antistatic film.

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

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

<Example 3>
Instead of the acrylic polymer (1) used in Example 1, an acrylic polymer (2) was used, and 0.5 parts by mass of an oxyalkylene group-containing compound KF353 (manufactured by Shin-Etsu Chemical Co., Ltd.) containing an organopolysiloxane was added. And the adhesive sheet was produced by the method similar to Example 1. FIG.

<Example 4>
Instead of the acrylic polymer (1) used in Example 1, an acrylic polymer (2) was used, and an oxyalkylene group-containing compound latemul PD-420 (manufactured by Kao Corporation) 0.2 containing no organopolysiloxane was used. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 with the addition of parts by mass.

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

<Example 8>
[Preparation of urethane adhesive solution]
As a polyol, 85 parts by mass of Preminol S3011 (manufactured by Asahi Glass Co., Ltd., Mn = 10000) which is a polyol having three hydroxyl groups, Sanniks GP3000 (manufactured by Sanyo Chemical Co., Ltd., Mn = 3000) 13 which is a polyol having three hydroxyl groups 2 parts by mass of Sannix GP1000 (Sanyo Kasei Co., Ltd., Mn = 1000) which is a polyol having three hydroxyl groups, 18 parts by mass of an isocyanate compound as a crosslinking agent (Coronate HX: C / HX, manufactured by Nippon Polyurethane Co., Ltd.) As a catalyst, iron (III) acetylacetonate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.04 parts by mass, ionic group-containing silicone X-40-2450 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 parts by mass, as a diluting solvent 210 mass parts of ethyl acetate was mix | blended and the urethane type adhesive solution was obtained. And the adhesive sheet which adjusted the heating conditions etc. and the thickness of the adhesive layer obtained by the method similar to Example 1 was produced.

<Example 9>
(Preparation of silicone adhesive solution)
As a silicone adhesive, “X-40-3229” (solid content 60 mass%, manufactured by Shin-Etsu Chemical Co., Ltd.) is 100 mass parts in solid content, and as a platinum catalyst, “CAT-PL-50T” (Shin-Etsu Chemical Co., Ltd.). 0.5 parts by mass), 0.5 parts by mass of ionic group-containing silicone X-40-2450 (manufactured by Shin-Etsu Chemical Co., Ltd.) and 100 parts by mass of toluene as a solvent were blended to obtain a silicone pressure-sensitive adhesive solution. . And the adhesive sheet which adjusted the heating conditions etc. and the thickness of the adhesive layer obtained by the method similar to Example 1 was produced.

<Comparative Examples 1 to 4>
Instead of the ionic group-containing silicone used in Example 2, an adhesive sheet was prepared in the same manner as in Example 2 except that the ionic compounds listed in Table 1 were used.

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

Table 1 shows the results of the above-described blending contents, various measurements and evaluations for the pressure-sensitive adhesive sheets according to Examples and Comparative Examples. The abbreviations in Table 1 will be described below.

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

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

  

From Table 1, it was confirmed that in all Examples, the antistatic property and the stability over time of the stripping voltage were excellent. Moreover, when adjusting and mix | blending the compounding quantity of ionic group containing silicone to the desired range, it has confirmed that it was excellent also in stain resistance (low pollution property).

On the other hand, from Table 1, in all comparative examples, since an antistatic agent such as an ionic liquid was used instead of the ionic group-containing silicone, the antistatic property and the stability over time of the peeling band voltage were improved compared to the examples. Inferiority was confirmed. In particular, since no ionic group-containing silicone was used, there was a case where a large increase in peeling voltage was observed over time, and the ionic compound contained in the pressure-sensitive adhesive layer permeated the polarizing plate surface over time. That is the reason.

The pressure-sensitive adhesive sheet disclosed herein protects the optical member during production, transportation and the like of 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. Therefore, it is suitable as a surface protective film. In particular, surface protective films (optical surfaces) applied to optical members such as polarizing plates (polarizing films) for liquid crystal display panels, wave plates, phase difference plates, optical compensation films, brightness enhancement films, light diffusion sheets, and reflective sheets It is useful as a protective film.

1: Adhesive sheet (surface protective film)
1 ': Adhesive sheet with separator (surface protective film)
DESCRIPTION OF SYMBOLS 10: Acrylic board 11: Separator 12: Ionic group containing silicone coating film 13: Adhesive layer 14: Base film 20: Polarizing plate 30: Sample fixing stand 40: Potential measuring device

Claims (7)

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

   

   
   (R ₁ to R ₄ may be the same or different and include any of an alkyl group having 1 to 10 carbon atoms, an alkoxy group, an aryl group, an alicyclic group, a fluorine-substituted alkyl group, and an ionic group, One or more of R ₁ to R ₄ contain an ionic group, and n is an integer of 0 to 100.)
2. The pressure-sensitive adhesive composition according to claim 1, comprising an oxyalkylene group-containing compound.
3. The pressure-sensitive adhesive composition according to claim 1 or 2, comprising at least one selected from the group consisting of an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive.
4. Having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 3, on at least one side of the base film;
   The pressure-sensitive adhesive sheet, wherein the ionic group-containing silicone is present inside and / or on the surface of the pressure-sensitive adhesive layer.
5. The pressure-sensitive adhesive sheet according to claim 4, wherein a separator is affixed to the surface of the pressure-sensitive adhesive layer opposite to the surface in contact with the base film.
6. The pressure-sensitive adhesive sheet according to claim 5, wherein the ionic group-containing silicone is present on a surface of the separator that contacts the pressure-sensitive adhesive layer.
7. An optical member comprising the pressure-sensitive adhesive sheet according to claim 4 or a pressure-sensitive adhesive sheet obtained by peeling the separator from the pressure-sensitive adhesive sheet according to claim 5 or 6.
   

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