JP2010185016A - Solvent type repeelable adhesive composition and repeelable adhesive product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To find out a solvent type repeelable adhesive composition which maintains transparency, adhesion reliability, high speed easy peelability and compatibility at a high level and which forms an adhesive layer hardly causing peeling electrification for the purpose of applying it to a surface protection film for optical films, and to provide a repeelable adhesive product obtained by using the composition and having good properties. <P>SOLUTION: The solvent type repeelable adhesive composition includes a cross-linking agent, an adhesive polymer having a functional group which reacts with the cross-linking agent, and an antistatic agent whose 0.1 mass% aqueous solution has a pH of 3.5-8.5. The repeelable adhesive product includes a supporting base material and an adhesive layer which is obtained from the adhesive composition and formed on at least one surface of the supporting base material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a re-peeling adhesive product that is peeled off again after being attached to an adherend, and exhibits excellent peelability even at high-speed peeling, and a solvent mold for producing this pressure-sensitive adhesive product It is related with the adhesive composition. More specifically, the present invention relates to an adhesive product for re-peeling for protecting the surface of optical members such as an optical polarizing plate (TAC), a retardation plate, an EMI (electromagnetic wave) shield film, an antiglare film, and an antireflection film. It is.

  For liquid crystal displays (LCD), plasma displays (PDP), etc., optical films having various functions, such as optical polarizing plates (TAC), retardation plates, EMI (electromagnetic wave) shield films, antiglare films, reflections, etc. A prevention film or the like is laminated and used. These optical films have a protective film affixed to the surface in order to prevent surface damage during the display manufacturing process and performance inspection stage. It is peeled off in the assembly process.

  The surface protection film is required to have transparency that does not interfere with performance inspection, punching processing, adhesion reliability that does not cause blistering or peeling during autoclaving and aging processing, and high-speed easy peeling that can be smoothly peeled off during high-speed peeling by machines And adaptability to the adherend.

  The present inventors have found a solvent-type re-peeling pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in high-speed peelability for the purpose of applying to an optical film surface protective film, and have already filed an application ( Patent Document 1).

  However, recently, antistatic performance has been required for surface protective films. This is because static electricity is generated when the surface protective film is peeled off at high speed by a machine, and this static electricity causes dust or cut scraps of the optical film to adhere to the optical film. This is because a problem arises in that the alignment of the liquid crystal panel is disturbed and the liquid crystal panel cannot be inspected.

  In order to suppress the generation of static electricity during the high-speed peeling of the surface protective film (hereinafter referred to as peeling charging), a method of adding an antistatic agent to the film substrate (for example, Patent Document 2), charging on the surface opposite to the adhesive layer There is a method of providing a prevention layer (for example, Patent Document 3), but it is insufficient to suppress peeling charge.

  For this reason, it was considered to add an antistatic agent to the pressure-sensitive adhesive layer itself. For example, Patent Document 4 discloses a surface protective film containing an alkyltrimethylammonium salt and an acrylic polymer having a hydroxyl group. Although this technique can suppress peeling electrification, there is a problem that the adhesive strength at the time of low-speed peeling is lowered, and the adhesion reliability is lowered.

JP 2008-74976 A Japanese Patent Laid-Open No. 4-292934 Japanese Patent Laid-Open No. 7-26223 JP 2005-131957 A

  Therefore, in the present invention, for the purpose of applying to the surface protection film of an optical film, an adhesive that maintains transparency, adhesion reliability, high-speed easy peelability and conformability at a high level and hardly causes peeling charge. An object was to find a solvent-type re-peeling pressure-sensitive adhesive composition capable of forming an agent layer and to provide a re-peeling pressure-sensitive adhesive product having good characteristics using this composition.

  The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention has a crosslinking agent, a pressure-sensitive adhesive polymer having a functional group capable of reacting with the crosslinking agent, and a 0.1% by mass aqueous solution having a pH of 3.5 to 8.5. It contains an antistatic agent.

  A mode in which the pressure-sensitive adhesive polymer includes a mixture of a low Tg polymer (A) having a glass transition temperature (Tg) of less than 0 ° C. and a high Tg polymer (B) having a Tg of 0 ° C. or more, the low Tg polymer (A ) And the above-described high Tg polymer (B) and any of the embodiments including a block polymer may be employed. In the latter embodiment, the pressure-sensitive adhesive polymer may further contain the high Tg polymer (B).

  The antistatic agent is preferably a cationic antistatic agent, and more preferably a quaternary ammonium salt.

  The crosslinking agent is preferably a polyisocyanate compound, and may be a mixture of an aromatic polyisocyanate compound and an aliphatic and / or alicyclic polyisocyanate compound.

  The present invention also includes a re-peeling pressure-sensitive adhesive product in which a pressure-sensitive adhesive layer obtained from the solvent-based re-peeling pressure-sensitive adhesive composition of the present invention is formed on at least one surface of a support substrate. This re-peeling pressure-sensitive adhesive product is preferably used as a surface protective film for an optical member.

  In the present invention, the antistatic agent having a 0.1% by weight aqueous solution having a pH of 3.5 to 8.5 is used, but the reason is not clear. The present invention succeeded in finding a solvent-type re-peeling pressure-sensitive adhesive composition capable of forming an excellent pressure-sensitive adhesive layer. Therefore, the adhesive product for re-peeling suitable as a surface protection film for optical members was able to be provided.

  First, the solvent-based re-peeling pressure-sensitive adhesive composition according to the present invention will be described. However, the scope of the present invention is not limited to these descriptions, and the gist of the present invention is not impaired except for the following examples. Changes can be made as appropriate within the range.

  The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention (hereinafter sometimes simply referred to as a pressure-sensitive adhesive composition) forms a pressure-sensitive adhesive layer by applying to a support base and then drying (removing the solvent). Is. The essential components of the pressure-sensitive adhesive composition are a cross-linking agent, a pressure-sensitive adhesive polymer capable of reacting with the cross-linking agent, and an antistatic agent in which the pH of a 0.1% by mass aqueous solution is 3.5 to 8.5. The “polymer” in the present invention includes not only a homopolymer but also a copolymer or a ternary or higher copolymer. The “monomer” of the present invention is an addition polymerization type monomer.

<Adhesive polymer>
The pressure-sensitive adhesive polymer used in the present invention is not particularly limited as long as it is a polymer that can react with a crosslinking agent described later and can exhibit adhesiveness. “Can react with the crosslinking agent” means that a functional group having reactivity with the functional group of the crosslinking agent is introduced into the polymer. For example, if the crosslinking agent has an isocyanate group. The pressure-sensitive adhesive polymer preferably has a hydroxyl group and / or a carboxyl group, and if the crosslinking agent has an epoxy group, the pressure-sensitive adhesive polymer preferably has a carboxyl group. In terms of reactivity, a combination in which the crosslinking agent has an isocyanate group and the pressure-sensitive adhesive polymer has a hydroxyl group is preferable.

  However, for the purpose of the present invention, it is preferable to select a pressure-sensitive adhesive polymer that is excellent in conformability and free from adherend contamination while balancing the low-speed peel adhesive strength and the high-speed peel adhesive strength. Therefore, a low Tg polymer (A) having a Tg of less than 0 ° C. for expressing the adhesive strength and a high Tg polymer (B) having a Tg of 0 ° C. or higher for preventing an increase in the high-speed peel adhesive strength are used in combination. It is preferable. In addition, if it is a low Tg polymer (A) whose Tg is less than 0 degreeC, it can be used independently as an adhesive polymer of this invention.

<Low Tg polymer (A) having a Tg of less than 0 ° C.>
A low Tg polymer (A) having a Tg of less than 0 ° C. (hereinafter simply referred to as “low Tg polymer (A)”) is used for developing adhesive force. The Tg of the low Tg polymer (A) is preferably −20 ° C. or lower, more preferably −35 ° C. or lower. However, if the Tg of the low Tg polymer (A) is lower than -80 ° C, the cohesive force tends to decrease, and the adhesive residue tends to occur, such being undesirable.

Here, the Tg of the polymer can be determined by DSC (differential scanning calorimeter), DTA (differential thermal analyzer), and TMA (thermomechanical analyzer). In addition, since the Tg of the homopolymer is described in various documents (for example, the polymer handbook), the Tg of the copolymer can be calculated from the Tg _n (K) of the various homopolymers and the mass fraction (W _n ) of the monomer as follows. It can also be obtained by an expression.

ここで Ｗ_ｎ ；各モノマーの質量分率
Ｔｇ_ｎ；各モノマーのホモポリマーのＴｇ（Ｋ）

Where W _n ; mass fraction of each monomer
Tg _n : Tg (K) of homopolymer of each monomer

  The Tg of the main homopolymer is 106 ° C. for polyacrylic acid, 8 ° C. for polymethyl acrylate, −22 ° C. for polyethyl acrylate, −54 ° C. for poly n-butyl acrylate, and −70 ° C. for poly 2-ethylhexyl acrylate. Poly-2-hydroxyethyl acrylate is −15 ° C., poly-2-hydroxyethyl methacrylate is 71 ° C., polymethyl methacrylate is 105 ° C., polyvinyl acetate is 30 ° C., polyacrylonitrile is 125 ° C., and polystyrene is 100 ° C.

  In order to obtain the low Tg polymer (A), it is preferable to use the alkyl (meth) acrylate (a-1) and the functional group-containing monomer (a-2) in combination. The alkyl (meth) acrylate (a-1) is necessary for ensuring adhesive strength, and the functional group-containing monomer (a-2) has a low Tg polymer (A) with a functional group for reacting with a crosslinking agent described later. It is a monomer to be introduced into.

  The alkyl (meth) acrylate (a-1) preferably has 4 to 12 carbon atoms in the alkyl group from the viewpoint of adhesive properties. This carbon number is preferably 4 to 10, more preferably 4 to 8. If the carbon number is less than 4 (3 or less) or more than 12 (13 or more), the adhesive strength may be reduced. Specifically, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, amyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) ) Acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) ) Acrylate, dodecyl (meth) acrylate, etc., among which butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate and isooctyl acrylate are more preferable. These may be used alone or in combination of two or more, and is not limited.

  As the functional group-containing monomer (a-2), 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone-modified hydroxy (meth) acrylate, α- (hydroxymethyl) ) Hydroxyl group-containing (meth) acrylates such as mono (meth) acrylate of polyester diol obtained from methyl acrylate, α- (hydroxymethyl) ethyl acrylate, phthalic acid and propylene glycol; (meth) acrylic acid, silica Unsaturated monocarboxylic acids such as cinnamic acid and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and citraconic acid; carboxyl group-containing monomers such as monoesters of these unsaturated dicarboxylic acids; amino groups and amides Group Examples include (meth) acrylates having any of a poxy group and the like. Of these, hydroxyl group-containing (meth) acrylates are preferred.

  The alkyl (meth) acrylate (a-1) is preferably used in the range of 50 to 99.9% by mass in 100% by mass of the raw material monomer of the low Tg polymer (A). More preferably, it is 60-99.7 mass%, More preferably, it is 70-99.5 mass%. If the usage-amount of alkyl (meth) acrylate (a-1) is in the said range, the adhesive obtained will show sufficient adhesive force and tack, However, When less than 50 mass%, adhesive strength and There is a possibility that the wettability to the adherend may be insufficient, and if it exceeds 99.9% by mass, the amount of the functional group-containing monomer (a-2) that becomes a crosslinking point is too small, and the high-speed adhesive force may be too high. There is.

  The functional group-containing monomer (a-2) is preferably 0.1 to 10% by mass. If there are few functional groups, the speed of crosslinking reaction will become slow, or high-speed adhesive force will become large too much, but if it exceeds 10 mass%, the adhesive strength of adhesive and the wettability to the adherend will tend to decrease. Therefore, it is not preferable. The amount of the functional group-containing monomer (a-2) used is more preferably 0.3 to 8% by mass, and still more preferably 0.5 to 6% by mass.

  In synthesizing the low Tg polymer, another monomer (a-3) may be copolymerized. The other monomer (a-3) can be copolymerized with the alkyl (meth) acrylate (a-1) and the functional group-containing monomer (a-2), and (a-1) and (a -2) other monomers. For example, alkyl (meth) acrylates other than the alkyl (meth) acrylate (a-1); halogen-substituted products of aliphatic unsaturated hydrocarbons such as ethylene and butadiene and aliphatic unsaturated hydrocarbons such as vinyl chloride; Aromatic unsaturated hydrocarbons such as styrene and α-methylstyrene; vinyl esters such as vinyl acetate; vinyl ethers; esters of allyl alcohol and various organic acids; ethers of allyl alcohol and various alcohols; acrylonitrile, etc. Of unsaturated cyanide compounds. These may be used alone or in combination of two or more, and is not limited. The other monomer (a-3) is preferably 0 to 49.9% by mass in 100% by mass of the raw material monomer mixture. When it exceeds 49.9 mass%, since the quantity of an alkyl (meth) acrylate (a-1) or a functional group containing monomer (a-2) decreases as a result, a desired adhesion characteristic cannot be obtained. A more preferred upper limit is 40% by mass, and a still more preferred upper limit is 30% by mass.

  The most preferred embodiment of the low Tg polymer (A) is a polymer obtained from a raw monomer mixture comprising 2-ethylhexyl acrylate, butyl acrylate, and hydroxyethyl acrylate. This polymer has good adhesive properties and also approximates the refractive index of polyvinyl acetate or polymethyl acrylate suitable as a high Tg polymer (B), so the haze of the resulting adhesive layer is reduced. be able to. When the total of 2-ethylhexyl acrylate, butyl acrylate, and hydroxyethyl acrylate is 100% by mass, 2-ethylhexyl acrylate is 20 to 80% by mass, butyl acrylate is 20 to 80% by mass, and hydroxyethyl acrylate is 0.8%. 5-5 mass% is preferable. Of course, the above-mentioned (a-1) to (a-3) other than these can also be used in combination, but when applied to applications where haze is important, 2-ethylhexyl acrylate, butyl acrylate, and hydroxyethyl The monomer other than acrylate is preferably 10% by mass or less.

  The low Tg polymer (A) preferably has a mass average molecular weight (Mw) of 100,000 or more from the viewpoint of improving the adhesive properties. In addition, when the grafting and / or block polymerization method described later is adopted, the molecular weight of only the low Tg polymer (A) cannot be measured, but in that case, the total of the low Tg polymer (A) and the high Tg polymer (B) The Mw is preferably 50,000 to 800,000. Within this range, the adhesive force in the re-peeling process does not become excessive, and particularly when the heat treatment by an autoclave or the like is performed after being attached to the adherend, the optical member is damaged or the optical member from the liquid crystal cell. The surface protective film can be peeled without causing troubles such as peeling. If the total Mw of the low Tg polymer (A) and the high Tg polymer (B) is less than 50,000, an increase in adhesive strength after heat treatment may occur, which is not preferable. Further, when the total Mw of the low Tg polymer (A) and the high Tg polymer (B) exceeds 800,000, the fluidity of the pressure-sensitive adhesive is lowered, and there are irregularities subjected to anti-glare (AG) treatment or the like. When the polarizing plate is used as an adherend, the pressure-sensitive adhesive may not sufficiently wet the polarizing plate surface. The range of Mw in the whole of the more preferable low Tg polymer (A) and high Tg polymer (B) is 100,000 to 600,000.

<High Tg polymer (B) with Tg of 0 ° C. or higher>
A high Tg polymer (B) having a Tg of 0 ° C. or higher (hereinafter simply referred to as a high Tg polymer (B)) has an effect of suppressing an increase in high-speed peeling force, and the Tg must be 0 ° C. or higher. Don't be. In order to further improve the high-speed peelability, the Tg of the high Tg polymer (B) is preferably 5 ° C. or higher. However, if the Tg of the high Tg polymer (B) is too high, although it may be a slightly adhesive type for re-peeling, the adhesive strength may be insufficient. Therefore, it is preferably less than 80 ° C, preferably 75 ° C or less, and 70 ° C. The following is more preferable.

  In the high Tg polymer (B), it is preferable that a functional group having reactivity with a crosslinking agent to be blended later is introduced. By crosslinking the high Tg polymer (B), the high Tg polymer (B) having a relatively low molecular weight that causes adherend contamination is increased in molecular weight, thereby suppressing adherend contamination. Examples of the functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group.

  In order to introduce the functional group into the high Tg polymer (B), the functional group-containing monomer (a-2) may be used as a raw material monomer of the high Tg polymer (B). Also in the case of the high Tg polymer (B), a hydroxyl group is preferable as the functional group, and therefore it is preferable to use hydroxyl group-containing (meth) acrylates among the functional group-containing monomer (a-2). These functional group-containing monomers are preferably 0.1 to 10% by mass in 100% by mass of the raw material monomer of the high Tg polymer (B). When the amount of the functional group-containing monomer used is less than 0.1% by mass, the amount of the functional group in the high Tg polymer (B) decreases, and the effect of suppressing adherend contamination is not sufficiently exhibited, which is not preferable. On the other hand, if it exceeds 10% by mass, the adhesive strength increases with time after adhesion to an adherend (adhesion progress), which is not preferable. The use amount of the functional group-containing monomer is more preferably 0.3 to 8% by mass, and further preferably 0.5 to 6% by mass.

  As the copolymerization partner of the functional group-containing monomer in obtaining the high Tg polymer (B), any known radical polymerizable monomer can be used, but the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition of the present invention. In order to reduce the haze, vinyl acetate is preferably used. Since the refractive index of the vinyl acetate polymer is close to the refractive index of the (meth) acrylate polymer (particularly a polymer containing 2-ethylhexyl acrylate or butyl acrylate) which is the main component of the low Tg polymer (A), It is because a haze becomes small and it becomes suitable as a film for surface protection of an optical film. Therefore, the high Tg polymer (B) is preferably obtained from a raw material monomer that essentially contains vinyl acetate and the functional group-containing monomer. At this time, 70-99.9 mass% of vinyl acetate is preferable, 80-99.9 mass% is more preferable, 90-99.9 mass% is further more preferable.

  Instead of vinyl acetate, methyl acrylate may be used as a copolymerization partner for the functional group-containing monomer. Adhesiveness and familiarity are improved. The methyl acrylate is preferably 70 to 99.9% by mass, more preferably 80 to 99.9% by mass, and still more preferably 90 to 99.9% by mass.

  In addition to vinyl acetate, methyl acrylate and other functional group-containing monomers, other monomers that can be used for the synthesis of high Tg polymer (B) include (meth) acrylic acid, methyl methacrylate, ethyl having a high homopolymer Tg. (Meth) acrylate, acrylonitrile, styrene and the like are preferable. In addition, the monomers (a-1) and (a-3) exemplified as the raw material monomers for the low Tg polymer (A) are also the types and amounts so that the Tg of the high Tg polymer (B) is 0 ° C. or higher. It can be used if selected. The molecular weight Mw of the high Tg polymer (B) is preferably about 2000 to 100,000. A more preferable range of Mw is about 20,000 to 90,000.

<Combination method of low Tg polymer (A) and high Tg polymer (B)>
The pressure-sensitive adhesive polymer of the present invention may use a low Tg polymer (A) alone, but is preferably a combination of a low Tg polymer (A) and a high Tg polymer (B). This combination, that is, the method for producing the pressure-sensitive adhesive polymer of the present invention includes the following aspects (i) to (iv).

(I) A mode in which a low Tg polymer (A) having a Tg of less than 0 ° C. and a high Tg polymer (B) having a Tg of 0 ° C. or higher are blended. In order to obtain the pressure-sensitive adhesive polymer in this mode, the low Tg polymer (A) And the high Tg polymer (B) may be polymerized separately, and then both may be mixed (blended). The polymerization method is not particularly limited, but solution polymerization that allows easy removal of the heat of polymerization is preferred. Examples of the polymerization solvent include aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate; alicyclic hydrocarbons such as cyclohexane; and aliphatic hydrocarbons such as hexane and pentane. However, it is not particularly limited as long as the polymerization reaction is not inhibited. These solvents may be used alone or in combination of two or more. What is necessary is just to determine the usage-amount of a solvent suitably.

  Reaction conditions such as polymerization reaction temperature and reaction time are not particularly limited, and may be set as appropriate according to, for example, the composition and amount of the monomer. Further, the reaction pressure is not particularly limited, and may be any of normal pressure (atmospheric pressure), reduced pressure, and increased pressure. The polymerization reaction is desirably performed in an inert gas atmosphere such as nitrogen gas.

  The polymerization catalyst (polymerization initiator) is not particularly limited. Methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, lauroyl peroxide, t-butyl peroxy octoate , T-butyl peroxybenzoate, organic peroxides such as trade name “NIPER (registered trademark) BMT-K40” (manufactured by NOF Corporation; mixture of m-toluoyl peroxide and benzoyl peroxide), '-Azobisisobutyronitrile (Nippon Hydrazine Kogyo Co., Ltd .; “ABN-R”), 2,2′-azobis (2-methylbutyronitrile) (Nippon Hydrazine Kogyo Co., Ltd .; “ABN-E”), 2,2'-azobis (2,4-dimethylvaleronitrile) (Nippon Hydrazine Industries) Ltd.; "ABN-V") azo compounds such like. In addition, known molecular weight regulators represented by mercaptans such as dodecyl mercaptan can also be used.

  In order to blend the low Tg polymer (A) and the high Tg polymer (B), the solutions of both may be mixed with a disper or the like. In the aspect of (i), when the total of the low Tg polymer (A) and the high Tg polymer (B) is 100% by mass, the low Tg polymer (A) is 80 to 96% by mass, and the high Tg polymer (B It is preferable to mix so that it may become 4-20 mass%. By using both in this range, the adhesive strength, conformability, high-speed easy peelability and the like are well balanced.

(Ii) A mode in which a low Tg polymer (A) having a Tg of less than 0 ° C. and a high Tg polymer (B) having a Tg of 0 ° C. or higher are grafted by a two-stage polymerization method. In this method, the monomer for (B) is polymerized by solution polymerization, and then the monomer for the low Tg polymer (A) is polymerized in the presence of the high Tg polymer (B) solution. In this two-stage polymerization method, the addition of the low Tg polymer (A) monomer to the reactor is started after the polymerization rate of the high Tg polymer (B) monomer reaches about 70 to 95% by mass, or a separate high Tg polymer is used. It is preferable to synthesize (B) and add the monomer for the low Tg polymer (A) after adding the high Tg polymer (B) solution to the reactor. The polymerization rate (% by mass) is a ratio of the mass of the monomer in the reaction vessel converted into a polymer (non-volatile content), and can be easily obtained by measuring the non-volatile content. The monomer for the low Tg polymer (A) is preferably added dropwise to the reactor together with the polymerization initiator. Mw of the obtained graft polymer (hereinafter referred to as graft polymer (C)) can be increased. In addition, as a polymerization initiator, it is preferable to utilize organic peroxides, such as a benzoyl peroxide. It is easy to cause a hydrogen abstraction reaction from the high Tg polymer (B), and the graft polymer (C) can be obtained with high efficiency.

  In this two-stage polymerization method, the high Tg polymer (B) is preferably used so as to be 10 to 35% by mass (including the post-added high Tg polymer (B)).

  By the two-stage polymerization, a polymer (C) obtained by grafting a low Tg polymer (A) onto a high Tg polymer (B) is obtained. In addition, when the above configuration is reversed and the monomer for the high Tg polymer (B) is polymerized in the presence of the low Tg polymer (A), the graft obtained by grafting the high Tg polymer (B) onto the low Tg polymer (A). A polymer (C) is obtained. In any embodiment, a part of the high Tg polymer (B) or the low Tg polymer (A) homopolymer may be generated. What is necessary is just to use these mixtures as an adhesive polymer.

  The Mw of the graft polymer (C) is preferably 50,000 to 800,000. Within this range, the adhesive force in the re-peeling process does not become excessive, and particularly when the heat treatment by an autoclave or the like is performed after being attached to the adherend, the optical member is damaged or the optical member from the liquid crystal cell. The surface protective film can be peeled without causing troubles such as peeling. When Mw is smaller than 50,000, there is a possibility that an increase in adhesive strength after heat treatment may occur, which is not preferable. Moreover, when Mw exceeds 800,000, the fluidity | liquidity of an adhesive will fall and when an uneven | corrugated polarizing plate which performed the glare-proof (AG) process etc. will be used as an adherend, an adhesive will carry out polarizing plate surface. There is a risk that it will not be able to wet sufficiently. A more preferable range of Mw is 100,000 to 600,000.

  The high Tg polymer (B) polymerized separately can be further blended after the two-stage polymerization of the high Tg polymer (B) and the low Tg polymer (A) is completed, and used as an adhesive polymer. The composition of the post-added high Tg polymer (B) is preferably the same as the initially polymerized (or added to the reactor) high Tg polymer (B), but the molecular weight may be different, As a result, the effect of reducing the adhesive strength of high-speed peeling appears. Moreover, the high Tg polymer (B) initially added to the reactor and the high Tg polymer (B) to be added later may be synthesized at the same time. The process can be simplified.

(Iii) A mode in which a low Tg polymer (A) having a Tg of less than 0 ° C. and a high Tg polymer (B) having a Tg of 0 ° C. or higher are grafted by a macromonomer method. In addition, a method using a macromonomer, an ionic polymerization method, a method of introducing a branch polymer into a main chain polymer by a polymer reaction, and the like are also known. In order to synthesize the second graft polymer of the present invention (hereinafter referred to as graft polymer (D)), it is easy to control the molecular weight of the main chain polymer and the branch polymer, it is possible to suppress the formation of a homopolymer, and A macromonomer method that can easily link the main chain polymer and the branch polymer is suitable. Specifically, the graft polymer (D) may be synthesized by converting the high Tg polymer (B) into a macromonomer in order to make it a branched polymer.

  The macromonomer (b-1) is a monomer in which a radical polymerizable double bond is introduced at the end of the high Tg polymer (B). Although there are various methods for synthesizing the macromonomer (b-1), a high Tg polymer (B) is polymerized using a chain transfer agent having a functional group, and the end of the high Tg polymer (B) is linked. Introducing a functional group derived from a transfer agent and chemically reacting a monomer having a functional group capable of reacting with the functional group and a radical polymerizable double bond with the functional group at the end of the high Tg polymer (B). Is relatively simple.

  In the present invention, a compound having a carboxyl group and / or a hydroxyl group and at least one thiol group in the same molecule is preferably used as the chain transfer agent. For example, thioglycolic acid, 2-mercaptopropionic acid, Carboxyl group-containing mercapto compounds such as 3-mercaptopropionic acid, thiomalic acid, mercaptostearic acid, mercaptoacetic acid, mercaptobutyric acid, mercaptooctanoic acid, mercaptobenzoic acid, mercaptonicotinic acid, cysteine, N-acetylcysteine, mercaptothiazole acetic acid, Examples thereof include hydroxyl group-containing mercapto compounds such as mercaptoethanol. These chain transfer agents are preferably about 0.05 to 1 part by mass with respect to 100 parts by mass of the monomer for the high Tg polymer (B).

  When the mercapto compound has a carboxyl group, an aliphatic epoxy monomer such as glycidyl (meth) acrylate, allyl glycidyl ether or 4-hydroxybutyl acrylate glycidyl ether; an alicyclic ring such as 3,4-epoxycyclohexylmethyl (meth) acrylate By reacting a formula epoxy monomer; 2- (vinyloxyethoxy) ethyl (meth) acrylate; 2-isopropenyl-2-oxazoline; N- (meth) acryloylaziridine; 3- (meth) acryloxymethyloxetane These monomers are bonded to the high Tg polymer (B) via a chain transfer agent to obtain the macromonomer (b-1). When the mercapto compound has a hydroxyl group, (meth) acryloyl isocyanate; (meth) acryloyl ethyl isocyanate, (meth) acryloyl alkyl isocyanate such as (meth) acryloylpropyl isocyanate; 2- (meth) acryloyloxyethyl isocyanate; (Meth) acryloyloxyalkyl isocyanates such as 3- (meth) acryloyloxypropyl isocyanate; isocyanate monomers such as 3-isopropenyl-α, α′-dimethylbenzyl isocyanate; 2- (vinyloxyethoxy) ethyl (meth) What is necessary is just to make acrylate etc. react. Hereinafter, these monomers for introducing a double bond at the terminal of the high Tg polymer (B) may be referred to as a monomer for macromonomer (b-2).

  The polymerization of the high Tg polymer (B) used for the macromonomer (b-1) may be performed by a known method, and as long as the chain transfer agent is used in the preferred amount, the same polymerization method as in the embodiment (i) described above. Can be adopted.

  By the polymerization, a high Tg polymer (B) having a carboxyl group or a hydroxyl group derived from the chain transfer agent used for the production of the high Tg polymer (B) at one end is obtained. After obtaining the high Tg polymer (B), a radical polymerizable double bond introduction reaction is subsequently carried out. The macromonomer monomer (b-2) having reactivity with a carboxyl group or a hydroxyl group at one end of the high Tg polymer (B) is directly added to, for example, a solution of the high Tg polymer (B) after polymerization. Alternatively, it may be added after diluted with a solvent or the like. Further, if necessary, a catalyst suitable for each reaction can be appropriately selected and used.

  For example, when synthesizing a high Tg polymer (B) using a chain transfer agent having a carboxyl group and introducing a radical polymerizable double bond using the monomer for macromonomer (b-2) having a glycidyl group Can use an esterification catalyst to allow the reaction to proceed rapidly. As the esterification catalyst, amines such as triethylamine; quaternary ammonium salts such as tetraethylammonium chloride; phosphorus compounds such as triphenylphosphine, etc., which are commonly used as esterification catalysts may be used. The reaction temperature is preferably about 70 to 120 ° C., and the reaction time is preferably about 2 to 10 hours. The end point of the reaction can be determined by acid value measurement or the like.

In the case of synthesizing a high Tg polymer (B) using a chain transfer agent having a hydroxyl group and introducing a radical polymerizable double bond using the monomer for macromonomer (b-2) having an isocyanate group In order to accelerate the reaction, a known metal catalyst or amine catalyst can be used. Examples of the metal catalyst include dibutyltin dilaurate, tin octoate, dibutyltin di (2-ethylhexanoate), lead 2-ethylhexanoate, 2-ethylhexyl titanate, 2-ethylhexanoate iron, 2- Examples include ethyl hexanoate cobalt, zinc naphthenate, cobalt naphthenate, and tetra-n-butyltin. Examples of amine catalysts include tertiary amines such as tetramethylbutanediamine. The reaction is preferably performed at about 50 to 100 ° C. for about 30 minutes to 10 hours. The end point of the reaction can be confirmed by the disappearance of the peak around 2270 cm ⁻¹ derived from the NCO group by IR measurement.

  The radical polymerizable double bond introduction reaction may be performed by adding a polymerization inhibitor as necessary. Specific examples of the polymerization inhibitor include hydroquinone, methylhydroquinone, t-butylhydroquinone, p-methoxyphenol, and the like, but are not particularly limited.

  As the reaction ratio, the monomer for macromonomer (b-2) is 0.8 to 1 (molar ratio) with respect to the functional group derived from the chain transfer agent at the terminal of the high Tg polymer (B), for example, carboxyl group or hydroxyl group. ) Is preferable.

  The macromonomer (b-1) of the high Tg polymer (B) is obtained by the radical polymerizable double bond introduction reaction. Then, this macromonomer (b-1) and the monomer for low Tg polymer (A) used as a principal chain polymer are polymerized. Use the macromonomer (b-1) so that the macromonomer (b-1) is about 3 to 30% by mass in a total of 100% by mass of the monomer for the main chain polymer and the low Tg polymer (A). Is preferred. If it is less than 3% by mass, the high-speed peelability may be insufficient. If it is more than 30% by mass, the adhesive force at low speed may be lowered or the conformability may be lowered, which is not preferable. The more preferable usage-amount of a macromonomer (b-1) is 5-25 mass%. As the polymerization method, the same polymerization method as in the above embodiment (i) can be employed.

  By polymerizing the monomer for the low Tg polymer (A) that becomes the main chain polymer with the macromonomer (b-1), a graft polymer (D) obtained by grafting the high Tg polymer (B) onto the low Tg polymer (A) is obtained. . The Mw of the graft polymer (D) is preferably 50,000 to 800,000 (more preferably 100,000 to 600,000) for the same reason as that for the graft polymer (C).

(Iv) A mode in which a low Tg polymer (A) having a Tg of less than 0 ° C. and a high Tg polymer (B) having a Tg of 0 ° C. or higher are linked by block polymerization. As a method for producing a block polymer, an organometallic compound is used as an initiator. In addition to a method of performing ionic polymerization, a method of performing radical polymerization using an iniferter, a method of performing radical polymerization using a polyvalent mercaptan (for example, Japanese Patent No. 2842782, Japanese Patent No. 3385177) and the like. A method using a polyvalent mercaptan is preferable because it is inexpensive.

  Examples of polyvalent mercaptans include trimethylolpropane trithioglycolate, trimethylolpropane trithiopropionate, pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, dipentaerythritol hexakisthioglycolate, dipentaerythritol. At least one compound selected from hexakisthiopropionate is preferred. A so-called star block polymer is obtained in which the same number of polymer chains as the valence of mercaptan extend radially from the polyvalent mercaptan residue. The amount of polyvalent mercaptan used is preferably about 0.1 to 2 parts by mass with respect to 100 parts by mass of the monomer.

  In the present invention, the monomer for the high Tg polymer (B) is first polymerized in the presence of a polyvalent mercaptan. When the polymerization rate of the monomer for the high Tg polymer (B) reaches 70% or more (more preferably 80% or more, more preferably 90% or more), the polymerization is started by adding the monomer for the low Tg polymer (A). . In the polymerization of the block polymer, as long as the polyvalent mercaptan is used in the above preferred amount, the same polymerization method as in the above-described embodiment (i) can be employed.

  Thereby, the star-shaped block polymer which the block polymer which the low Tg polymer (A) part connected with the high Tg polymer (B) part extended radially is obtained. The Mw of the star block polymer is preferably 50,000 to 800,000 (more preferably 100,000 to 600,000) for the same reason as in the case of the graft polymer (C).

<Crosslinking agent>
The pressure-sensitive adhesive composition of the present invention essentially contains a crosslinking agent. As the crosslinking agent, a compound having two or more functional groups capable of reacting with the functional groups of the low Tg polymer (A) and the high Tg polymer (B) is used.

  For example, if the low Tg polymer (A) and the high Tg polymer (B) have a hydroxyl group, a polyisocyanate compound is preferred as the cross-linking agent, and if it has a carboxyl group, a polyisocyanate compound or polyepoxy Compounds and the like are preferred.

  Examples of the polyepoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A type epoxy resin, N, N, N ′, N′-tetraglycidyl-m-xylene. Examples thereof include diamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine and the like.

  In terms of reactivity, the low Tg polymer (A) and the high Tg polymer (B) have a hydroxyl group, and it is preferable to use a polyisocyanate compound as a crosslinking agent. As the polyisocyanate compound, any of an aromatic polyisocyanate compound, an aliphatic or alicyclic polyisocyanate compound can be used.

  Examples of aromatic polyisocyanate compounds include bifunctional or trifunctional diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate, metaxylylene diisocyanate, 1,5-naphthalene diisocyanate, and triphenylmethane triisocyanate. Functional aromatic polyisocyanates; adduct compounds obtained by reacting these polyisocyanates with polyhydric alcohols such as dipropylene glycol, diethylene glycol, 1,6-hexanediol, and trimethylolpropane; the aromatic polyisocyanates Uretdione compounds, biuret compounds, isocyanurate compounds and the like which are dimers or trimers of the same class. Among these, tolylene diisocyanate-based polyisocyanate compounds are particularly preferable in that they have an excellent balance between low-speed peel adhesive strength and high-speed peel adhesive strength.

  More specifically, “Coronate (registered trademark) L”, “Coronate 2030”, “Millionate (registered trademark) MR-100”, “Millionate 200” (all manufactured by Nippon Polyurethane Industry Co., Ltd.); Trademark) E1240 "," Desmodur M100 "(all from Sumika Bayer Urethane Co., Ltd.);" Takenate (registered trademark) 500 "," Takenate D-110N "," Cosmonate (registered trademark) ND "(all Mitsui Chemical polyurethane) and the like are commercially available. These can be used alone or in combination of two or more.

  Examples of the aliphatic or alicyclic polyisocyanate compound include aliphatic or alicyclic compounds such as hexamethylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, norbornene diisocyanate, and hydrogenated products of the above aromatic polyisocyanates. Polyisocyanates; adduct compounds obtained by reacting these polyisocyanates with polyhydric alcohols such as dipropylene glycol, diethylene glycol, 1,6-hexanediol, trimethylolpropane; the above aliphatic or alicyclic groups Examples thereof include uretdione compounds, biuret compounds, isocyanurate compounds which are dimers or trimers of polyisocyanates. Among these, a hexamethylene diisocyanate-based polyisocyanate compound is particularly preferable because it is excellent in the balance between the conformability and the high-speed peeling adhesive force.

  More specifically, for example, “Coronate HX”, “Coronate HL”, “Coronate 2234” (all manufactured by Nippon Polyurethane Industry); “Death Module N3400”, “Death Module Z4480 BA” (all Sumika Bayer) "Takenate 600", "Takenate 700", "Takenate D-120N", "Cosmonate NBDI" (all manufactured by Mitsui Chemicals Polyurethanes); "Duranate (registered trademark) D-201", "Duranate" 24A-100 "," Duranate TSE-100 "(manufactured by Asahi Kasei Co., Ltd.) and the like are commercially available. These can be used alone or in combination of two or more.

  When an aromatic polyisocyanate compound and an aliphatic or alicyclic polyisocyanate compound are used in combination, the conformability can be improved while balancing low-speed peel adhesive strength and high-speed peel adhesive strength. This is an embodiment. In mixing and using an aromatic polyisocyanate compound and an aliphatic or alicyclic polyisocyanate compound, the aromatic / aliphatic or alicyclic group preferably has a mass ratio of 90/10 to 10/90, 80/20 to 20/80 is more preferable.

  These crosslinking agents are preferably added so as to be 0.1 to 2 equivalents when the total of the functional groups of the low Tg polymer (A) and the high Tg polymer (B) is 1 equivalent. If the amount of the crosslinking agent is too small, the cohesive force of the resulting pressure-sensitive adhesive may be insufficient and the high-speed peeling adhesive force may become too large. On the other hand, if it exceeds 2 equivalents, the conformability (wettability) is extremely lowered, which is not preferable. A more preferable amount of the crosslinking agent is 0.2 to 1.5 equivalents.

  As crosslinking accelerators, dibutyltin dilaurate, tin octoate, dibutyltin di (2-ethylhexanoate), lead 2-ethylhexanoate, 2-ethylhexyl titanate, 2-ethylhexanoate iron, 2-ethyl Hexanoate cobalt, zinc naphthenate, cobalt naphthenate, tetra-n-butyltin, or the like may be used.

<Antistatic agent>
In the pressure-sensitive adhesive composition of the present invention, an antistatic agent having a 0.1% by mass aqueous solution having a pH of 3.5 to 8.5 is also contained as an essential component. This antistatic agent is necessary for suppressing peeling charge. An antistatic agent having a pH of less than 3.5 in a 0.1% by weight aqueous solution or an antistatic agent having a pH exceeding 8.5 has a small effect of suppressing the peeling charge even if the amount of use is increased, and conversely has an adhesive property. It is not preferable because it deteriorates. A more preferable lower limit of the pH is 4.0, and an upper limit is 8.0.

  The antistatic agent exhibiting a pH in the above range is considered to have moderate compatibility with the pressure-sensitive adhesive polymer used in the present invention. That is, if the compatibility between the pressure-sensitive adhesive polymer and the antistatic agent is too good, the antistatic agent is difficult to bleed on the surface of the pressure-sensitive adhesive layer, and thus the peeling charge suppressing effect is not exhibited. On the other hand, if the compatibility is too bad, almost all of the added antistatic agent bleeds on the surface of the pressure-sensitive adhesive layer, causing adherend contamination. However, since the antistatic agent having a pH in the above range bleeds on the surface even when used in a small amount and shows a good peeling charge suppressing effect, it does not cause adherend contamination, so the pressure-sensitive adhesive polymer used in the present invention It is thought that it has moderate compatibility without excess and deficiency.

  The antistatic agent that can be used in the present invention is not limited as long as it exhibits a pH in the above range, and any of a nonionic antistatic agent, an anionic antistatic agent, and a cationic antistatic agent can be used. Examples of the nonionic antistatic agent include “Neugen (registered trademark) ET-83” (Daiichi Kogyo Seiyaku Co., Ltd .; polyoxyethylene oleyl seryl ether). Examples of the anionic antistatic agent include “Homogenol (registered trademark) L-100” (manufactured by Kao Corporation; special polymer surfactant), “Exel (registered trademark)” (manufactured by Kao Corporation; stearic acid monoglyceride), “ Plysurf (registered trademark) M28F "(Daiichi Kogyo Seiyaku Co., Ltd .;) and the like.

  Among the above, as the antistatic agent, a cationic antistatic agent is preferable. The cationic antistatic agent is an antistatic agent having a cationic group such as primary to tertiary amine salt, quaternary ammonium salt, imidazolinium salt, pyridinium salt and the like. Specifically, “Katiogen (registered trademark) ES-O (Daiichi Kogyo Seiyaku Co., Ltd .; octyldimethylethylammonium ethyl sulfate),“ Katiogen (registered trademark) ES-L-9 (Daiichi Kogyo Seiyaku Co., Ltd .; Lauril) Dimethylethylammonium ethyl sulfate), “Elegan (registered trademark) 264WAX” (manufactured by NOF Corporation), “Nopcostat (registered trademark) 092” (amine salt type; manufactured by San Nopco), “DM-50PM” (Yoshimura Oil Chemical Co., Ltd.) Alkylamine quaternary ammonium salt), “Elix (registered trademark) SEI-52” (manufactured by Yoshimura Oil Chemical Co., Ltd .; alkylamide quaternary ammonium salt), “Elik NP-85R” (manufactured by Yoshimura Oil Chemical Co., Ltd .; alkylamide) Quaternary ammonium salt), "Eleique LS-30" (manufactured by Yoshimura Oil Chemical Co., Ltd .; alkyl amide quaternary ammonia) Unsalted) and the like, may be used alone or two or more thereof. Of these, quaternary ammonium salts are preferred. More preferred is the “Elelique” series which are alkylamide trialkylammonium salts. These have a structure in which a long-chain alkyl group is bonded to a trialkylammonium salt moiety via an amide group, and it is considered that excellent peeling charge suppressing ability is exhibited due to this structure.

  The antistatic agent is preferably 0.005 to 3 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive polymer. When the amount is less than 0.005 parts by mass, the ability to suppress peeling charge may be insufficient. A more preferable lower limit of the amount of the antistatic agent is 0.1 part by mass. On the other hand, when the amount is more than 3 parts by mass, the adhesive properties, particularly the low-speed peeling adhesive force, tends to decrease, such being undesirable. The amount of the antistatic agent is preferably as small as possible if the peeling charge suppressing effect is exhibited, and the preferable upper limit is 2 parts by mass, more preferably 1 part by mass, and still more preferably 0.5 parts by mass.

<Solvent-type re-peeling pressure-sensitive adhesive composition>
The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive polymer produced by combining the low Tg polymer (A) and the high Tg polymer (B) by the method described in (i) to (iv). And a crosslinking agent and the above-mentioned antistatic agent, it is preferable from the viewpoint of coating properties to mix and mix the crosslinking agent and the antistatic agent in the adhesive polymer solution.

  The nonvolatile content of the pressure-sensitive adhesive composition is not particularly limited, but is preferably, for example, 10 to 80% by mass, more preferably 20 to 70% by mass, and further preferably 25 to 60% by mass. In order to increase the storage stability of the pressure-sensitive adhesive composition before blending the cross-linking agent, it is better that the non-volatile content is 40% by mass or more, as in the case of applying immediately after preparing the pressure-sensitive adhesive composition, When it is not necessary to consider storage stability, the non-volatile content may be prepared so as to have a viscosity suitable for coating. When the non-volatile content is less than 10% by mass, drying after application or the like takes a long time, which may reduce productivity. Moreover, when it exceeds 80 mass%, the viscosity of the whole composition will become high, handling property and applicability | paintability may lack, and there exists a possibility that it may become impractical. As the solvent for the pressure-sensitive adhesive composition, any of the polymerization solvents described above can be used, and as described above, the same solvent as the polymerization solvent is preferable.

  The pressure-sensitive adhesive composition of the present invention includes known crosslinking accelerators, tackifiers, modifiers, pigments, colorants, fillers, anti-aging agents, UV absorbers, UV stabilizers, and antistatic agents described above. Additives such as antistatic agents may be added as long as the object of the present invention is not impaired.

<Removable adhesive product>
The pressure-sensitive adhesive composition of the present invention is used for production of a re-peeling pressure-sensitive adhesive product. An adhesive product (adhesive tape or sheet), base having an adhesive layer formed on one side of the substrate by applying the adhesive composition on a supporting substrate or release paper and forming a dry coating film thereof. A pressure-sensitive adhesive product having a pressure-sensitive adhesive layer formed on both surfaces of the material and a pressure-sensitive adhesive product having only a pressure-sensitive adhesive layer without a substrate can be obtained. In the case of producing a paper base adhesive product, it is also possible to employ a method in which an adhesive composition is applied on a release paper to form an adhesive layer and then transferred to a paper base material. In forming the pressure-sensitive adhesive layer, it is desirable to perform heat drying under conditions where the solvent scatters (for example, at about 50 to 120 ° C. for about 30 to 180 seconds).

  As the base material, conventionally known papers such as fine paper, kraft paper, crepe paper, glassine paper; plastics such as polyethylene, polypropylene, polyester, polystyrene, polyethylene terephthalate, polyvinyl chloride, cellophane; woven fabric, non-woven fabric, etc. Textile products: These laminates can be used. When used for protecting the surface of an optical film, the support substrate is preferably a transparent film such as polyethylene terephthalate.

  The method for applying the pressure-sensitive adhesive composition to the substrate is not particularly limited, and a known method such as a roll coating method, a spray coating method, or a dipping method can be employed. In this case, any of a method for directly applying the pressure-sensitive adhesive composition to the substrate, a method for applying the pressure-sensitive adhesive composition to a release paper, and then transferring the coated material onto the substrate can be employed. After apply | coating an adhesive composition, an adhesive layer is formed on a base material by making it dry.

  For example, release paper may be attached to the surface of the pressure-sensitive adhesive formed on the substrate. The pressure-sensitive adhesive surface can be suitably protected and preserved. The release paper is peeled off from the pressure-sensitive adhesive surface when the pressure-sensitive adhesive product is used. In addition, when the pressure-sensitive adhesive surface is formed on one side of a base material such as a sheet or tape, a release agent layer may be formed by applying a known release agent to the back surface of the base material. By winding the pressure-sensitive adhesive sheet (tape) in a roll shape with the pressure-sensitive adhesive layer on the inside, the pressure-sensitive adhesive layer comes into contact with the release material layer on the back of the substrate, so that the pressure-sensitive adhesive surface is protected and preserved. The

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the scope of the present invention is not limited only to these examples. Unless otherwise specified, “%” indicates “mass%” and “part” indicates “part by mass”.

[Measurement Method of Mass Average Molecular Weight (Mw)]
Using “HLC-8220GPC” manufactured by Tosoh Corporation as a GPC measuring apparatus, measurement was performed under the following conditions, and a polystyrene standard sample converted value was defined as Mw.
Column: “TSKgel Super HZM-H” x 3 manufactured by Tosoh Corporation Solvent: Tetrahydrofuran Flow rate: 0.35 ml / min Injection volume: 10 μl / time Sample concentration: 0.2%

[Tg]
It is Tg calculated by the above formula. In addition, Tg of the homopolymer of each monomer is polyvinyl acetate: 30 ° C., polymethyl acrylate: 8 ° C., polybutyl acrylate: −54 ° C., poly 2-hydroxyethyl acrylate: −15 ° C., poly 2-ethylhexyl acrylate: −70 ° C.

Synthesis Example 1 [Synthesis of Low Tg Polymer (A)]
150 parts of n-butyl acrylate (BA), 335 parts of 2-ethylhexyl acrylate (2EHA) and 15 parts of 2-hydroxyethyl acrylate (HEA) were weighed and mixed well to prepare a monomer mixture. 40% of this monomer mixture and 240 parts of ethyl acetate were added to a flask equipped with a thermometer, stirrer, inert gas inlet tube, reflux condenser and dropping funnel. For dropwise addition comprising 60% of the remaining monomer mixture and 0.625 part of “Niper (registered trademark) BMT-K40” (manufactured by NOF Corp .; mixture of m-toluoyl peroxide and benzoyl peroxide) as a polymerization initiator The monomer mixture was placed in a dropping funnel and mixed well. While circulating nitrogen gas, the internal temperature of the flask was raised to 84 ° C., and 0.25 part of “Nyper BMT-K40” was charged into the flask to initiate polymerization. The dropping of the monomer mixture for dripping was started after 10 minutes had passed after the polymerization initiator was charged. The monomer mixture for dripping was dripped uniformly over 1 hour. After completion of the dropwise addition, 100 parts of ethyl acetate was added to the flask. After completion of the dropwise addition, 1 hour, 1 hour and a half, and 2 hours later, “ABN-E” (manufactured by Nippon Hydrazine Kogyo Co., Ltd., 2,2′-azobis (2-methylbutyrate) was used as a booster (post-added polymerization initiator). Nitrile)] and 0.25 parts of ethyl acetate. Further, aging was carried out for 3 hours under reflux conditions to obtain a low Tg polymer (A) having a Mw of 581,000 and a calculated Tg of -64 ° C. The composition and characteristics are shown in Table 1.

Synthesis Example 2 [Synthesis of high Tg polymer (B)]
112.8 parts of vinyl acetate (VAc) and 263 parts of ethyl acetate as a solvent were added to a flask equipped with a thermometer, a stirrer, an inert gas introduction tube, a reflux condenser and a dropping funnel. While flowing nitrogen gas under stirring, the internal temperature of the flask was raised to 75 ° C. and diluted with 1.1 parts of ethyl acetate as a polymerization initiator “Laurox” (manufactured by Kayaku Akzo; Lauroyl peroxide) 0 .12 parts was added to the flask to initiate the polymerization.

  After 30 minutes from the start of the reaction, a mixture consisting of 24 parts of VAc, 4.2 parts of HEA, 0.14 part of “Laurox” and 52 parts of ethyl acetate was added dropwise to the flask over 1 hour. Immediately after that, 0.7 parts of “Laurox” diluted with 6.3 parts of ethyl acetate was added as a booster, and then further aged at 76 ° C. for 2 hours, and a high Tg of 30% nonvolatile content synthesized from VAc and HEA An ethyl acetate solution of polymer (B) was obtained. The high Tg polymer (B) had a Tg of 28 ° C. and an Mw of 69,000. The composition and characteristics are shown in Table 1.

Synthesis Example 3 [Synthesis of Graft Polymer (C) by Two-stage Polymerization Method]
In a flask equipped with a thermometer, stirrer, inert gas introduction tube, reflux condenser and dropping funnel, 45 parts of high Tg polymer (B) obtained in Synthesis Example 2 above (15 parts as solid content), low As Tg polymer monomers, 27 parts of BA, 20.3 parts of 2EHA, 2.7 parts of HEA and 120 parts of ethyl acetate were charged and mixed well. While the nitrogen gas was circulated under stirring, the internal temperature of the flask was raised to 82 ° C., and 0.12 part of “Niper BMT-K40” was charged into the flask to initiate polymerization.

  After 15 minutes from the start of the reaction, a mixture of 63 parts of BA, 140.7 parts of 2EHA, 6.3 parts of HEA, 0.26 parts of “Nyper BMT-K40” and 152.4 parts of ethyl acetate was added over 1 hour. It was dripped in the flask. After the completion of the dropwise addition, 1.5 hours and 2.5 hours later, 1.1 parts of “ABN-E” and 54.9 parts of ethyl acetate were added in 3 portions as a booster. Thereafter, it was further aged at 78 ° C. for 2 hours. A graft polymer (C) having an Mw of 40,000 having a calculated Tg of −64 ° C. of the low Tg polymer portion was obtained. The composition and characteristics are shown in Table 2.

Synthesis Example 4 [Synthesis of Graft Polymer (D) by Macromonomer Method]
280 parts of methyl acrylate (MA), 0.9 part of 2-mercaptoethanol as chain transfer agent, 343 parts of ethyl acetate as solvent, equipped with thermometer, stirrer, inert gas introduction tube, reflux condenser and dropping funnel Added to the flask. While flowing nitrogen gas under stirring, the internal temperature of the flask was raised to 80 ° C., and 0.14 part of “ABN-E” diluted with 13.9 parts of ethyl acetate was added to the flask as a polymerization initiator. The polymerization was started.

  After 10 minutes from the start of the reaction, a mixture consisting of 420 parts of MA, 1.34 parts of 2-mercaptoethanol, 0.14 part of “ABN-E” and 14 parts of ethyl acetate was added dropwise to the flask over 1 hour. After completion of the dropping, the dropping funnel was washed with 112 parts of ethyl acetate and added to the flask. After 50 minutes from the end of dropping, 0.07 part of “ABN-R” (manufactured by Nippon Hydrazine Kogyo Co., Ltd .; 2,2′-azobisisobutyronitrile) diluted with 7 parts of ethyl acetate was added as a booster. did. After the addition, the mixture was further aged at 80 ° C. for 4 hours, and then 215 parts of ethyl acetate was added to complete the reaction. A high Tg polymer (polymethyl acrylate; PMA) for macromonomer was obtained.

  Next, a radical polymerizable double bond introduction reaction with respect to the PMA was performed. 1400 parts of the above PMA solution, 3.64 parts of “Karenz AOI (registered trademark)” (manufactured by Showa Denko KK; 2-acryloylethyl isocyanate) as a monomer for macromonomer, “ANTAGE-W400” [Kawaguchi Chemical Co., Ltd.] as a polymerization inhibitor 2,2′-methylenebis (4-methyl-6-tert-butylphenol)] and 42 parts of ethyl acetate were equipped with a thermometer, stirrer, gas inlet tube, reflux condenser and dropping funnel. Added to the flask. While stirring, a mixed gas of nitrogen gas and oxygen gas was circulated, the internal temperature of the flask was raised to 70 ° C., 0.28 parts of dibutyltin dilaurate was added as a reaction catalyst, and an addition reaction was started. The addition reaction was carried out for 3 hours while maintaining the internal temperature of the flask at 70 ° C. to complete the synthesis of the macromonomer. The macromonomer solution having a calculated Tg of 8 ° C. had a nonvolatile content concentration of 46.7% and Mw of 45,000.

  Next, in a flask equipped with a thermometer, a stirrer, an inert gas introduction tube, a reflux condenser and a dropping funnel, 205.6 parts of the macromonomer solution (96 parts as a solid content) as a monomer for a low Tg polymer 2EHA (232.8 parts) and HEA (7.2 parts) were added together with 0.34 parts of n-dodecyl mercaptan as a chain transfer agent and well mixed with 120 parts of ethyl acetate. While flowing nitrogen gas under stirring, the internal temperature of the flask was raised to 89 ° C., and 0.08 part of “ABN-E” diluted with 4 parts of ethyl acetate was added to the flask as a polymerization initiator, and polymerization was performed. Was started.

  After 10 minutes from the start of the reaction, 155.2 parts of 2EHA, 4.8 parts of HEA, 137 parts of the above macromonomer solution (64 parts as a solid content), 0.22 parts of n-dodecyl mercaptan, “ABN-E” 0.04 And a mixture of 160 parts of ethyl acetate was added dropwise to the flask over 1 hour. After completion of the dropping, the dropping funnel was washed with 40 parts of ethyl acetate and added to the flask.

  From the 3rd to 4th hour from the start of the reaction, 1.2 parts of “ABN-R” diluted with 36.8 parts of ethyl acetate was added in 3 portions as a booster. Thereafter, the mixture was further aged at 78 ° C. for 2 hours to obtain a graft polymer (D) having a high Tg polymer content of 28.5% and a calculated Tg of the low Tg polymer portion of −69 ° C. The solution of the obtained graft polymer (D) had a nonvolatile content concentration of 52.0% and Mw of 143,000. The composition and characteristics are shown in Table 2.

Synthesis Example 5 (Synthesis of star block polymer)
200 parts of MA, “PEMP” (manufactured by Sakai Chemical Industry; pentaerythritol tetrakis (3-mercaptopropionate)) as polyvalent mercaptan, 380 parts of ethyl acetate, thermometer, stirrer, inert gas introduction tube, To a flask equipped with a reflux condenser and dropping funnel. While flowing nitrogen gas under stirring, the internal temperature of the flask was raised to 80 ° C., and 0.1 part of “ABN-R” diluted with 9.9 parts of ethyl acetate was added to the flask as a polymerization initiator. The polymerization was started.

  After 10 minutes from the start of the reaction, a mixture consisting of 300 parts of MA, 6 parts of “PEMP”, 0.05 part of “ABN-R” and 145 parts of ethyl acetate was added dropwise to the flask over 1 hour and a half. After completion of the dropping, the dropping funnel was washed with 80 parts of ethyl acetate and added to the flask.

  After 4 hours and 40 minutes from the start of polymerization, 0.1 part of “ANTAGE-W400” and 10 parts of ethyl acetate were added to complete the reaction. The polymerization rate was 90.2%, calculated Tg 8 ° C., Mw 36,000. Of a high Tg polymer was obtained.

  Next, in a flask equipped with a thermometer, a stirrer, an inert gas introduction tube, a reflux condenser and a dropping funnel, 118.2 parts of the high Tg polymer solution (48 parts as a solid content), as a monomer for the low Tg polymer, 155.2 parts of 2EHA, 4.8 parts of HEA and 108 parts of ethyl acetate were charged and mixed well. While flowing nitrogen gas under stirring, the internal temperature of the flask was raised to 88 ° C., and 0.08 part of “ABN-E” diluted with 4 parts of ethyl acetate as a polymerization initiator was put into the flask to start polymerization. I let you.

  After 10 minutes from the start of the reaction, 177.3 parts of the above high Tg polymer solution (72 parts as solids), 232.8 parts of 2EHA, 7.2 parts of HEA, 0.04 part of “ABN-E”, and ethyl acetate The mixture with 176 parts was added dropwise into the flask over 1 hour. After completion of the dropping, the dropping funnel was washed with 40 parts of ethyl acetate and added to the flask. From 3 hours after the start of polymerization to 4 hours later, 1.2 parts of “ABN-R” and 36.8 parts of ethyl acetate were added in 3 portions as a booster. Thereafter, aging was carried out at 78 ° C. for 2 hours to obtain a star-shaped block polymer having a high Tg polymer portion content of 23.1%, a calculated Tg of the low Tg polymer portion of −67 ° C. and Mw of 276,000. The composition and characteristics are shown in Table 2.

Example 1
“Nopcostat (registered trademark) 092” having a pH of 7.05 in a 0.1% aqueous solution as the antistatic agent 1 with respect to 100 parts of the solid content of the solution of the low Tg polymer (A) obtained in Synthesis Example 1. (San Nopco; amine salt type cationic antistatic agent) 1.0 part, dibutyltin dilaurate 250 ppm as crosslinking accelerator, aliphatic polyisocyanate compound “Duranate (registered trademark) 24A-100” as crosslinking agent (Asahi Kasei Co., Ltd .; hexamethylene diisocyanate type, trifunctional biuret body) 3.7 parts (0.8 equivalent) was added and stirred well to obtain an adhesive composition.

  The pressure-sensitive adhesive composition was applied using a polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc .; thickness: 38 μm) as a supporting substrate so that the thickness after drying was 20 μm, and then at 100 ° C. for 2 minutes. An adhesive film was prepared by drying. After sticking and protecting the PET film which gave the mold release process on the surface of the adhesive layer, it was cured in an atmosphere of 23 ° C. for 1 week.

  The pressure-sensitive adhesive film after curing was evaluated for the adhesive property, the peeling charging property and the adherend contamination by the methods described later. The evaluation results are shown in Table 3.

Examples 2 and 3
As shown in Table 3, an adhesive film was obtained in the same manner as in Example 1 except that the kind and amount of the antistatic agent to be added were changed, and the adhesive properties, release charging properties and adherend were obtained by the methods described later. Contamination was evaluated. The evaluation results are shown in Table 3. In Table 3, antistatic agent 2 means “DM-50PM” (manufactured by Yoshimura Oil Chemical Co., Ltd .; alkylamine quaternary ammonium salt), and antistatic agent 3 is “ELIK (registered trademark) SEI-52”. (Yoshimura Oil Chemical Co., Ltd .; alkylamide trialkyl quaternary ammonium salt).

Example 4
As a crosslinking agent, in addition to aliphatic “Duranate (registered trademark) 24A-100”, aromatic “coronate L-55E” (manufactured by Nippon Polyurethane; Tolylene diisocyanate, trifunctional adduct) is used. The pressure-sensitive adhesive film was obtained in the same manner as in Example 3 except that the amount of the crosslinking agent to be added was changed to the amount shown in Table 3, and evaluated for the pressure-sensitive adhesive properties, peeling charging properties and adherend contamination by the methods described later. did. The evaluation results are shown in Table 3.

Example 5
As an adhesive polymer solution, 10 parts of the high Tg polymer (B) solution obtained in Synthesis Example 2 was mixed with 100 parts of the solid content of the low Tg polymer (A) solution obtained in Synthesis Example 1. A pressure-sensitive adhesive film was obtained in the same manner as in Example 2 except that the amount of the crosslinking agent to be added was changed to the amount shown in Table 3, and the pressure-sensitive adhesive properties, peeling charge properties and adherend contamination were obtained by the methods described later. Evaluated. The evaluation results are shown in Table 3.

Example 6
An adhesive film was obtained in the same manner as in Example 5 except that the antistatic agent to be added was changed to the antistatic agent 4 and the kind and amount of the crosslinking agent to be added were changed as described in Table 3. The properties, peel charge properties and adherend contamination were evaluated. The evaluation results are shown in Table 3. In Table 3, the antistatic agent 4 means “Eleique (registered trademark) LS-30” (manufactured by Yoshimura Oil Chemical Co., Ltd .; alkylamide trialkyl quaternary ammonium salt).

Example 7
The pressure-sensitive adhesive polymer solution obtained by mixing 19 parts of the high Tg polymer (B) solution obtained in Synthesis Example 2 with the solid content of 100 parts of the graft polymer (C) solution obtained in Synthesis Example 3 The adhesive film was obtained in the same manner as in Example 2 except that the amount of the crosslinking agent to be added was changed to the amount shown in Table 3, and the adhesive properties, peeling charging properties, and adherend contamination were determined by the methods described later. evaluated. The evaluation results are shown in Table 3.

Example 8
An adhesive film was obtained in the same manner as in Example 7 except that the antistatic agent to be added was changed to the antistatic agent 5 and the type and amount of the crosslinking agent to be added were changed as described in Table 3. The properties, peel charge properties and adherend contamination were evaluated. The evaluation results are shown in Table 3. In Table 3, the antistatic agent 5 means “Eleique (registered trademark) NP-85R” (manufactured by Yoshimura Oil Chemical Co., Ltd .; alkylamide trialkyl quaternary ammonium salt).

Example 9
Using the graft polymer (D) solution obtained in Synthesis Example 4 as the pressure-sensitive adhesive polymer solution, the pressure-sensitive adhesive film was obtained in the same manner as in Example 3 except that the amount of the crosslinking agent added was changed to the amount shown in Table 3. The adhesion characteristics, peeling charge characteristics and adherend contamination were evaluated by the methods described below. The evaluation results are shown in Table 3.

Examples 10-1, 10-2, 10-3
The amount of the antistatic agent to be added was changed to the amount shown in Table 3, and the adhesive film was obtained in the same manner as in Example 9 except that the type of crosslinking agent to be added and the amount were changed as shown in Table 3. The adhesion characteristics, peeling charge characteristics and adherend contamination were evaluated by the methods described below. The evaluation results are shown in Table 3.

Example 11
Using the star-shaped block polymer solution obtained in Synthesis Example 5 as an adhesive polymer solution, the crosslinking agent to be added is “Duranate (registered trademark) D-201” (manufactured by Asahi Kasei Corporation; hexamethylene diisocyanate type, bifunctional adduct). In addition, an adhesive film was obtained in the same manner as in Example 2 except that the amount of the crosslinking agent was changed to the amount shown in Table 3, and the adhesive properties, peeling charging properties, and adherend contamination were evaluated by the methods described later. The evaluation results are shown in Table 3.

Example 12
An adhesive film was obtained in the same manner as in Example 11 except that the antistatic agent to be added was changed to the antistatic agent 4 and the kind and amount of the crosslinking agent to be added were changed as described in Table 3. The properties, peel charge properties and adherend contamination were evaluated. The evaluation results are shown in Table 3.

Comparative Example 1
An adhesive film was obtained in the same manner as in Example 1 except that the antistatic agent to be added was changed to the antistatic agent 6 and the addition amount was changed as described in Table 3. Characteristics and adherend contamination were evaluated. The evaluation results are shown in Table 3. In Table 3, antistatic agent 6 is “Neugen (registered trademark) TDS-30” (Daiichi Kogyo Seiyaku Co., Ltd .; polyion), which is a nonionic antistatic agent having a pH of 8.73 in a 0.1% aqueous solution. Oxyethylene tridecyl ether).

Comparative Example 2
The pressure-sensitive adhesive film was the same as in Example 9, except that the antistatic agent to be added was antistatic agent 7, the addition amount was 0.5 parts, and the addition amount of the crosslinking agent was changed as shown in Table 3. The adhesion characteristics, peeling charging characteristics and adherend contamination were evaluated by the methods described below. The evaluation results are shown in Table 3. In Table 3, antistatic agent 7 is “Antox EHD-400” (manufactured by Nippon Emulsifier Co., Ltd .; polyoxyethylene alkyl ether phosphate), an anionic antistatic agent having a pH of 3.08 in a 0.1% aqueous solution. Fate).

<Characteristic evaluation method>
[PH measurement method]
It dissolved in ion-exchange water so that content of an antistatic agent might be 0.1%, and pH at 25 degreeC was measured using the pH meter (the product made by HORIBA, pH meter F-21). When the solubility in water was low, the solution was heated to 50 to 60 ° C. and dissolved as necessary, and then the pH at 25 ° C. was measured. In the measurement, the pH meter was corrected using pH standard buffers (manufactured by Hayashi Junyaku Kogyo Co., Ltd.) having pHs of 4.0, 7.0 and 9.0.

[Low speed peel strength]
A commercially available polarizing plate (a polarizing film manufactured by Kennis Co., Ltd. (product code: 1-115-821)) fixed to a 3 mm thick acrylic plate with a double-sided tape is used as an adherend, and an atmosphere at 23 ° C. and a relative humidity of 65%. Below, the pressure-sensitive adhesive film cut to a width of 25 mm is reciprocated once by a 2 kgf rubber roller to be pressure-bonded. After the pressure bonding, the film was allowed to stand for 24 hours, and the 180 ° peel adhesive strength was measured according to JIS K 6854 at a peel rate of 0.3 m / min in an atmosphere of 23 ° C., and pass / fail was judged according to the following criteria.
◎: 0.05 N / 25 mm or more ○: 0.04 N / 25 mm or more, less than 0.05 N / 25 mm Δ: 0.03 N / 25 mm or more, less than 0.04 N / 25 mm ×: less than 0.03 N / 25 mm

[High speed peel adhesion]
A commercially available polarizing plate (a polarizing film manufactured by Kennis Co., Ltd. (product code: 1-115-821)) fixed to a 3 mm thick acrylic plate with a double-sided tape is used as an adherend, and an atmosphere at 23 ° C. and a relative humidity of 65%. Below, the pressure-sensitive adhesive film cut to a width of 25 mm is reciprocated once by a 2 kgf rubber roller, and is subjected to pressure bonding. After the pressure bonding, the film was allowed to stand for 24 hours, measured at 180 ° peel adhesive strength according to JIS K 6854 at a peel rate of 30 m / min in an atmosphere of 23 ° C.
◎: Less than 0.6 N / 25 mm ○: 0.6 N / 25 mm or more, less than 0.75 N / 25 mm Δ: 0.75 N / 25 mm or more, less than 0.9 N / 25 mm x: 0.9 N / 25 mm or more

[Familiarity]
A test piece having a size of 4 cm × 4 cm is cut out from the adhesive film. A rough surface of a commercially available anti-glare type liquid crystal protective film (BUFFALO; BOF-H141S) having an uneven height difference of 5.7 μm (laser microscope: measured by “VK-9710” manufactured by Keyence Corporation) is used as an adherend. Use and place the anti-glare film horizontally on a flat surface with the rough side up. In an atmosphere of 23 ° C. and 65% relative humidity, one side of the test piece is attached to the antiglare film about 1 to 2 mm from the end, and then the test piece is gently placed on the antiglare film. The time from when the test piece began to get wet to the anti-glare film until the entire surface was completely adapted to the anti-glare film was measured, and judged according to the following criteria.
◎: The entire surface of the test piece fits within 30 seconds. ○: The surface of the test piece fits within 30 seconds, but within 60 seconds. △: The surface of the test piece conforms within 60 seconds, but within 120 seconds. X: Over 120 seconds for the entire specimen to adjust

[Peeling voltage]
A test piece having a size of 4 cm × 6 cm is cut out from the adhesive film. A test piece is attached to a commercially available polarizing plate [a polarizing film (product code: 3-115-821) manufactured by Kennis Co., Ltd.] and left in an atmosphere of 23 ° C. and 65% relative humidity for 24 hours. After a predetermined time has passed, the adhesive film is peeled off from the polarizing plate by hand, and immediately polarized using a digital electrostatic potential measuring device (Kasuga Denki Co., Ltd .; KSD-0103S) with a distance of 5 cm between the sensor and the polarizing plate. The voltage of the plate was measured. The peeling charge suppression effect was judged as pass / fail according to the following criteria.
◎: Less than 0.5 kV ○: 0.5 kV or more, less than 1.0 kV Δ: 1.0 kV or more, less than 2.0 kV ×: 2.0 kV or more

[Adherent contamination]
A test piece was affixed to the above polarizing plate and left in a 50 ° C. atmosphere for 24 hours. After a predetermined time, the pressure-sensitive adhesive film was peeled off, the contamination state of the polarizing plate surface was visually observed, and the contamination property was judged according to the following criteria.
◎: No contamination is seen ○: Very little contamination is seen ×: Contamination is seen as a whole

  Since the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention uses a specific antistatic agent, for example, the surface protective film provided with the pressure-sensitive adhesive layer is hardly charged even during high-speed mechanical peeling. Therefore, the optical member that is the adherend is not inconvenienced. In particular, when a pressure-sensitive adhesive polymer that combines a high Tg polymer and a low Tg polymer is used, the balance between the low-speed peel adhesive strength and the high-speed peel adhesive strength is excellent, and the conformability to the adherend is good. Exhibits good adhesive properties that it does not cause adherend contamination.

  Therefore, the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention is suitable for producing a re-peeling pressure-sensitive adhesive product, and the obtained re-peeling pressure-sensitive adhesive product comprises an optical polarizing plate (TAC), a retardation plate, It is useful as a surface protective film to protect the surface of optical members such as EMI (electromagnetic wave) shield films, antiglare films, antireflection films and the like. It can also be used as a protective film for the surface of other plastics and metal plates.

Claims (10)

  A solvent-type re-peeling comprising a cross-linking agent, a pressure-sensitive adhesive polymer having a functional group capable of reacting with the cross-linking agent, and an antistatic agent having a 0.1% by mass aqueous solution having a pH of 3.5 to 8.5. Pressure-sensitive adhesive composition.   The solvent type according to claim 1, wherein the pressure-sensitive adhesive polymer comprises a mixture of a low Tg polymer (A) having a glass transition temperature (Tg) of less than 0 ° C and a high Tg polymer (B) having a Tg of 0 ° C or higher. Re-peeling pressure-sensitive adhesive composition.   The solvent-type re-peeling pressure-sensitive adhesive composition according to claim 1 or 2, wherein the pressure-sensitive adhesive polymer comprises a graft and / or block polymer of the low Tg polymer (A) and the high Tg polymer (B).   The solvent-based re-peeling pressure-sensitive adhesive composition according to claim 3, wherein the pressure-sensitive adhesive polymer further contains the high Tg polymer (B).   The solvent type re-peeling pressure-sensitive adhesive composition according to any one of claims 1 to 4, wherein the antistatic agent is a cationic antistatic agent.   6. The solvent-based re-peeling pressure-sensitive adhesive composition according to claim 5, wherein the cationic antistatic agent is a quaternary ammonium salt.   The said crosslinking agent is a polyisocyanate compound, The solvent-type re-peeling adhesive composition in any one of Claims 1-6.   The pressure-sensitive adhesive composition for solvent-based re-peeling according to claim 7, wherein the crosslinking agent is a mixture of an aromatic polyisocyanate compound and an aliphatic and / or alicyclic polyisocyanate compound.   A pressure-sensitive adhesive product for re-peeling, wherein a pressure-sensitive adhesive layer obtained from the solvent-type re-peelable pressure-sensitive adhesive composition according to claim 1 is formed on at least one surface of a support substrate.   The pressure-sensitive adhesive product for re-peeling according to claim 9, which is used as a surface protective film for an optical member.