JP5496583B2 - Solvent-type re-peeling pressure-sensitive adhesive composition and re-peeling pressure-sensitive adhesive product - Google Patents

Description

  The present invention is a re-peeling product that is peeled again after being attached to an adherend, exhibits excellent peelability even at high-speed peeling, and has excellent antistatic performance, and The present invention relates to a solvent-type pressure-sensitive adhesive composition for producing a pressure-sensitive adhesive product. More specifically, an adhesive product for re-peeling for protecting the surface of an optical member such as an optical polarizing plate (TAC), a phase difference plate, an EMI (electromagnetic wave) shield film, an antiglare (antiglare) film, an antireflection film and the like. It is about.

  Liquid crystal displays, plasma displays, etc. are laminated with optical films having various functions, such as optical polarizing plates (TAC), retardation plates, EMI (electromagnetic wave) shield films, antiglare films, antireflection films, and the like. It is 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 protective film must have transparency that does not interfere with the performance test, and “familiarity” (wetability and stickability) that can be quickly applied to an adherend without biting air bubbles. It is important that there is no increase in adhesive strength after sticking to the adherend, no adherend adherence to the adherend, and the like. Furthermore, recently, as the size of the display has increased, the protective film has also increased in area, so that the peeling process has been mechanized, and as a result, the ability to easily perform high-speed peeling with a machine has become an important required characteristic.

  If the Tg of the pressure-sensitive adhesive polymer is simply increased in order to ensure this high-speed peelability, the adhesive strength and conformability during low-speed peel will be reduced, which is not practical. If the adhesive force at the time of low-speed peeling is low, for example, in the manufacturing process of the polarizing plate, there arises a disadvantage that the surface protective film is peeled off during each process such as punching, inspection, phase, and panel assembly. Further, if the conformability is poor, bubbles enter between the polarizing plate surface and the surface protective film, and in particular, an autoclave treatment or an aging treatment causes swelling and tunneling, which hinders the inspection process.

  Therefore, in the surface protective film, high speed peelability, low speed peelability, conformability and the like are important characteristics. However, on the other hand, the adhesive layer also requires antistatic performance in order to prevent troubles such as static electricity generated during high-speed peeling by machines, failure of electronic components, and adhesion of dust etc. to optical members. Is done. Conventionally, a surfactant acting as an antistatic agent has been added to the pressure-sensitive adhesive layer, but this causes surface contamination due to bleeding out or the like.

  Therefore, it has been performed to impart conductivity to the pressure-sensitive adhesive layer by combining a pressure-sensitive adhesive polymer having an alkylene oxide structure and a metal salt compound (for example, Patent Documents 1 and 2). Examination of these technologies revealed that the antistatic performance is good, but the adhesive with good conformability (wetting) has too high a high-speed peelability, and the crosslinking degree of the pressure-sensitive adhesive polymer is adjusted to reduce the high-speed peelability. Then, it turned out that low-speed peeling adhesive force falls significantly. That is, it was difficult to obtain a pressure-sensitive adhesive having all the characteristics of high-speed peelability, conformability, and adhesive strength at low-speed peel.

Japanese Patent Application Laid-Open No. 2005-206776 JP 2005-314579 A

  Therefore, in the present invention, for the purpose of applying to a surface protective film for optical members, etc., both high-speed peelability and conformability, which are contradictory properties, can be compatible, low-speed adhesive strength is also excellent, and antistatic performance is excellent A solvent-type re-peeling pressure-sensitive adhesive composition that can form a pressure-sensitive adhesive layer was found, and the problem was to provide a re-peeling pressure-sensitive adhesive product with good characteristics.

The present invention is a solvent-type re-peeling pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in antistatic performance,
A pressure-sensitive adhesive product in which a pressure-sensitive adhesive layer having a thickness of 20 μm obtained from the solvent-type re-peeling pressure-sensitive adhesive composition is formed on a polyethylene terephthalate film substrate having a thickness of 38 μm is prepared. When the 180 ° adhesive strength to an acrylic plate at 65% is measured, it is 1.6 N / 25 mm or less at high speed peeling at 30 m / min, and the adhesive strength at high speed peeling is 0.3 m / min at low speed peeling. The divided value is 18.0 or less, and the surface resistivity of the pressure-sensitive adhesive layer is less than 10 ¹³ Ω.

  When a 4 cm square sample is cut out from the adhesive product and placed on an adherend having a surface with an uneven height difference of 5 to 6 μm, the entire surface of the sample becomes wet with respect to the adherend. Is preferably 60 seconds or less.

  The present invention also includes a re-peeling pressure-sensitive adhesive product in which a pressure-sensitive adhesive layer obtained from the solvent-type re-peeling pressure-sensitive adhesive composition is formed on at least one surface of a support substrate. It is preferable to use for the surface protection film for optical members.

  The present invention also relates to a solvent-type re-peeling pressure-sensitive adhesive composition containing a pressure-sensitive adhesive polymer, wherein the pressure-sensitive adhesive polymer has a polymer structure having a glass transition temperature of 0 ° C. or higher and a carbon number of 4 to 12. A polymer structure synthesized from a raw material monomer component containing an alkyl (meth) acrylate (A) having an alkyl group, an alkylene oxide chain-containing monomer (B) and a functional group-containing monomer (C) as essential components, and a metal salt The compound is compounded.

  The pressure-sensitive adhesive polymer is preferably a graft polymer having a polymer structure having a glass transition temperature of 0 ° C. or higher in the side chain, and the graft polymer comprises a macromonomer (E) having a polymer structure having a glass transition temperature of 0 ° C. or higher. It is preferable that it is copolymerized. At this time, in 100% by mass of the raw material monomer component of the graft polymer, the alkyl (meth) acrylate (A) is 25 to 85% by mass, the alkylene oxide chain-containing monomer (B) is 5 to 70% by mass, and the functional group-containing monomer (C ) Is 0.3 to 8% by mass, the other monomer (D) is preferably 0 to 10% by mass, and the macromonomer (E) is preferably 3 to 30% by mass.

  It is a preferred embodiment of the present invention that the alkylene oxide chain-containing monomer is a monomer represented by the following formula (1).

[In the formula (1), R ¹ is an alkenyl group having 2 to 5 carbon atoms, and R and R ′ are either a hydrogen atom and one is a methyl group, or both are hydrogen atoms, R ² is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and n is an added mole number of alkylene oxide, which is 1 to 50. ]

In the present invention, the pressure-sensitive adhesive polymer comprises a polymer having a glass transition temperature of 0 ° C. or higher, the alkyl (meth) acrylate (A), the alkylene oxide chain-containing monomer (B), and the functional group-containing monomer (C ) As an essential component, a solvent-type re-peeling pressure-sensitive adhesive composition (mixture type) which is a mixture with a polymer synthesized from a raw material monomer component is also included. In this case, a polymer having a glass transition temperature of 0 ° C. or more and a raw material monomer component containing an alkyl (meth) acrylate (A), an alkylene oxide chain-containing monomer (B) and a functional group-containing monomer (C) as essential components are synthesized. When the total of the obtained polymers is 100% by mass, the polymer having a glass transition temperature of 0 ° C. or higher is preferably 3 to 30 % by mass. Also in this mixture type, the alkylene oxide chain-containing monomer is preferably a monomer represented by the above formula (1).

The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention produces a pressure-sensitive adhesive product in which a 20 μm-thick pressure-sensitive adhesive layer obtained from this pressure-sensitive adhesive composition is formed on a 38 μm-thick polyethylene terephthalate film substrate, When the adhesive strength of this adhesive product at 180 ° to an acrylic plate at 23 ° C. and 65% relative humidity was measured, it was 1.6 N / 25 mm or less at a high speed peeling of 30 m / min, and the adhesive strength at high speed peeling was 0.3 m. It is preferable that the value divided by the adhesive force at low speed peeling per minute is 18.0 or less, and the surface resistivity of the pressure-sensitive adhesive layer is less than 10 ¹³ Ω. In addition, when the pressure-sensitive adhesive product was prepared, a 4 cm square sample was cut out and placed on an adherend having a surface with an uneven height difference of 5 to 6 μm, the entire surface of the sample was against the film. It is also preferred that the time until wetting is 60 seconds or less.

  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. The product is preferably used for a surface protective film for optical members.

  The pressure-sensitive adhesive polymer used in the present invention has a polymer structure having a glass transition temperature (Tg) of 0 ° C. or higher and a polymer structure capable of improving adhesive properties and conformability. A re-peeling pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having excellent strength and conformability to an adherend and also having an antistatic ability could be provided. Therefore, it was possible to provide an adhesive product for re-peeling suitable for protecting the surface of optical members such as various displays and polarizing plates. In particular, it is suitable for an optical film having fine irregularities on its surface such as an antiglare (AG) -treated polarizing plate.

  The present inventors have been researching adhesives for re-peeling for a long time, and high Tg polymer and low Tg polymer blocks and / or polymers having a grafted structure have high-speed release properties and low-speed adhesion properties. It has been found that power and conformability are good in a good balance, and an application has already been filed (Japanese Patent Application No. 2008-72224). However, the technique described in the above application sometimes lacks the antistatic ability of the pressure-sensitive adhesive layer. Then, when many antistatic agents were examined, it was found that the use of a metal salt compound can impart good antistatic ability to the pressure-sensitive adhesive layer, and the present invention has been conceived. Hereinafter, the present invention will be described in detail. 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.

  The pressure-sensitive adhesive polymer used in the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention (hereinafter sometimes simply referred to as a pressure-sensitive adhesive composition) has a polymer structure having a glass transition temperature (Tg) of 0 ° C. or higher, and a carbon number. It has a polymer structure synthesized from a raw material monomer component containing an alkyl (meth) acrylate (A) having 4 to 12 alkyl groups, an alkylene oxide chain-containing monomer (B) and a functional group-containing monomer (C) as essential components. Is.

  In the pressure-sensitive adhesive composition of the present invention, a polymer structure having a Tg of 0 ° C. or higher (hereinafter sometimes simply referred to as a high Tg polymer structure), an alkyl (meth) acrylate (A), an alkylene oxide chain-containing monomer (B) and “Having” a polymer structure synthesized from a raw material monomer component containing the functional group-containing monomer (C) as an essential component (hereinafter sometimes simply referred to as an alkylene oxide polymer structure) is a block and / or graft polymer. When one type of pressure-sensitive adhesive polymer means to have both polymer structures, a polymer having a high Tg polymer structure (hereinafter sometimes simply referred to as a high Tg polymer) and a polymer having an alkylene oxide polymer structure (hereinafter, May be simply referred to as an alkylene oxide polymer) Results forming the adhesive polymer is, if the pressure-sensitive adhesive polymer is a means having both polymer structure (hereinafter, simply referred to as mixture type) is.

  A high Tg polymer structure is necessary to suppress an increase in high speed peel force. The alkylene oxide polymer structure ensures compatibility, and also helps to develop conductivity because ions generated by dissociation of the metal salt compound can move through the alkylene oxide chain. For this reason, both polymer structures are required for the pressure-sensitive adhesive polymer of the present invention.

[Block and / or graft polymer]
First, the case where the pressure-sensitive adhesive polymer is a block and / or graft polymer having both a high Tg polymer structure and an alkylene oxide polymer structure will be described. In the following, the graft polymer will be described, but the preferred monomer species and the amount thereof are the same for the block polymer.

  The graft polymer of the present invention is a polymer whose main chain exhibits adhesive force, and has a structure in which a high Tg polymer structure is grafted to this main chain.

[Alkyl (meth) acrylate (A)]
The first essential monomer component for obtaining the main chain of the graft polymer is an alkyl (meth) acrylate (A) having an alkyl group having 4 to 12 carbon atoms, thereby ensuring adhesive strength. From the viewpoint of adhesive properties, the alkyl group preferably has 4 to 10 carbon atoms, more preferably 4 to 9 carbon atoms. If the carbon number is less than 4 (3 or less) or more than 12 (13 or more), the adhesive strength may be reduced.

When considering the Tg of a polymer obtained only from an alkyl (meth) acrylate (A), it is necessary from the viewpoint of adhesive properties that it is lower than the Tg (0 ° C. or higher) of the side chain (branched polymer: high Tg polymer). The alkyl (meth) acrylate (A) is preferably selected so that the Tg is less than 0 ° C. The Tg of the polymer obtained only from the alkyl (meth) acrylate (A) is more preferably −20 ° C. or less, and further preferably −35 ° C. or less. However, Tg lower than −80 ° C. is not preferable because the cohesive force tends to decrease and adherend contamination tends to occur. The Tg of the homopolymer is described in various documents (for example, polymer handbooks), and the Tg of the copolymer is obtained from the following formula from the Tg _n (K) of each homopolymer and the mass fraction (W _n ) of the monomer. be able to.

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

  Specific examples of the alkyl (meth) acrylate (A) include 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, Examples include isononyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, and the like. Soviet nonyl acrylate is preferable. These may be used alone or in combination of two or more, and is not limited.

  The alkyl (meth) acrylate (A) is preferably used in the range of 25 to 85% by mass in 100% by mass of the raw material monomer component of the graft polymer. If the usage-amount of an alkyl (meth) acrylate (A) is in this range, the obtained adhesive will have a good balance of high-speed peelability, low-speed adhesive strength and conformability. If it is out of the above range, as a result, there are too many or too few other essential monomer components, which may result in insufficient low-speed adhesive strength and conformability, or high-speed adhesive strength. As for the usage-amount of an alkyl (meth) acrylate (A), 35-80 mass% is more preferable, More preferably, it is 55-80 mass%. The raw material monomer component for the branch polymer is also included in 100% by mass of the raw material monomer component of the graft polymer.

[Alkylene oxide chain-containing monomer (B)]
The second essential monomer component constituting the main chain of the graft polymer of the present invention is an alkylene oxide chain-containing monomer (B). This alkylene oxide chain-containing monomer (B) is used for enhancing the conformability and for dissolving the metal salt compound in the pressure-sensitive adhesive layer to develop antistatic ability. The alkylene oxide chain-containing monomer (B) is preferably an alkylene oxide chain-containing (meth) acrylic monomer and / or an alkylene oxide chain-containing monomer represented by the following formula (1).

[In the formula (1), R ¹ is an alkenyl group having 2 to 5 carbon atoms, and R and R ′ are either a hydrogen atom and one is a methyl group, or both are hydrogen atoms, R ² is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and n is an added mole number of alkylene oxide, which is 1 to 50. ]

  An alkylene oxide chain-containing (meth) acrylic monomer (hereinafter sometimes simply referred to as monomer (B-1)) has a (meth) acrylic monomer having an ethylene oxide (EO) chain and a propylene oxide (PO) chain. (Meth) acrylic monomers, (meth) acrylic monomers having both, and the like. The number of moles of ethylene oxide and / or propylene oxide added in the monomer (B-1) is preferably 1 to 30 moles and more preferably 2 to 10 moles from the viewpoint of improving the wettability due to the flow of the pressure-sensitive adhesive polymer. The terminal of the alkylene oxide chain may remain a hydroxyl group or may be substituted with another functional group such as a methyl group.

  A suitable monomer (B-1) can be represented by the following formula (2).

[R ″ is a hydrogen atom or a methyl group, and R, R ′ and R ² have the same meaning as in formula (1). N is 1 to 30.]

  Specific examples of the monomer (B-1) include methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxytripropylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) ) Alkoxypolyalkylene glycol (meth) acrylates such as acrylate, ethoxytriethylene glycol (meth) acrylate, butoxydiethylene glycol (meth) acrylate, butoxytriethylene glycol (meth) acrylate; phenoxydiethylene glycol (meth) acrylate, phenoxytriethylene glycol Aryloxypolyalkylene glycol (meth) acrylates such as (meth) acrylates Rate acids; 2-ethylhexyl diglycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate and the like, may be used alone or two or more thereof.

In addition, as the alkenyl group having 2 to 5 carbon atoms represented by R ¹ in the monomer represented by the above formula (1) (hereinafter sometimes referred to as monomer (B-2)), the following (i) vinyl Group, (ii) isopropenyl group, (iii) allyl group, (iv) methallyl group, (v) 3-butenyl group, (vi) 2-methyl-1-butenyl group, (vii) 3-methyl-1- Examples include butenyl group, (viii) 2-methyl-3-butenyl group, and (ix) 3-methyl-3-butenyl group. Among these, (iii) allyl group, (iv) methallyl group, and (ix) 3-methyl-3-butenyl group are preferable.

Moreover, as a C1-C8 hydrocarbon group shown by R < ² > in Formula 1 in a monomer (B-2), a methyl group, an ethyl group, a propyl group, an isopropyl group, a neopentyl group, a hexyl group, for example, Examples thereof include aliphatic hydrocarbon groups such as heptyl group and octyl group; aromatic hydrocarbon groups such as phenyl group, benzyl group and cresyl group. Among these, from the viewpoint of handleability, a hydrocarbon group having 1 to 4 carbon atoms or a hydrogen atom is preferable, and a hydrogen atom or a methyl group is more preferable. The case where R ¹ is a methallyl group and R ² is a hydrogen atom can be represented by the following chemical formula.

[R and R ′ are either a hydrogen atom and either a methyl group, or both are hydrogen atoms, and n is 1 to 50. ]

  These monomers (B-1) and (B-2) can be mixed and used as the monomer (B). As for the usage-amount of a monomer (B), about 5-70 mass% is preferable in 100 mass% of raw material monomer components of a graft polymer. If the amount is less than 5% by mass, the solubility of the metal salt may be too small and the metal salt may be precipitated. If the amount exceeds 70% by mass, the adhesive force and cohesive force of the adhesive product may be insufficient. It is not preferable. A more preferable amount of the monomer (B) is 7 to 60% by mass, and further preferably 15 to 40% by mass.

[Functional group-containing monomer (C)]
The 3rd essential monomer component for comprising the principal chain of the graft polymer of this invention is a functional group containing monomer (C) used as a crosslinking point. This is because the cross-linking reaction between the additional cross-linking agent and the graft polymer can increase the balance between high-speed peelability, conformability, and low-speed adhesive force in a balanced manner. Specific examples of the functional group-containing monomer (C) include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, caprolactone-modified hydroxy (meth) acrylate, α- (hydroxy Methyl) methyl acrylate, α- (hydroxymethyl) ethyl acrylate, hydroxyl group-containing (meth) acrylates such as mono (meth) acrylate of polyester diol obtained from phthalic acid and propylene glycol; (meth) acrylic acid, 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; Amido group And (meth) acrylates having any of epoxy groups and the like.

  Among the above, hydroxyl group-containing (meth) acrylates having a hydroxyl group as a functional group are preferable. In particular, when the hydroxyl group is located away from the (meth) acryloyl group, the cross-linking reactivity and conformability are improved. Therefore, when the amount of the cross-linking agent is to be reduced or the conformability to the adherend is particularly important. Is a (meth) acrylate (for example, 4-hydroxybutyl (meth) acrylate) in which a hydroxyl group is bonded to an alkyl group (propyl group or more) having a larger number of carbon atoms than 2-hydroxyethyl (meth) acrylate. It is preferable to use it.

  These functional group-containing monomers (C) are preferably 0.1 to 10% by mass in 100% by mass of the raw material monomer component of the graft polymer. When the amount of the functional group-containing monomer (C) used is less than 0.1% by mass, the amount of the functional group in the graft polymer decreases, the degree of cross-linking and cohesion of the adhesive is insufficient, and the adhesive strength becomes too large. Or adhesive residue may occur. Moreover, when it exceeds 10 mass%, since there exists a possibility that conformability may fall or the adhesive force at the time of low speed peeling may become small, it is unpreferable. 0.3-8 mass% is more preferable, and the usage-amount of a functional group containing monomer (C) has more preferable 0.5-6 mass%.

  In the synthesis of the graft polymer in the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention, another monomer (D) may be copolymerized. The other monomer (D) is a monomer that can be copolymerized with the essential monomer components (A) to (C) and that is other than these monomers. For example, alkyl (meth) acrylates other than the alkyl (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate; aromatic ring-containing (meth) acrylates such as benzyl (meth) acrylate; fats such as ethylene and butadiene Of aromatic unsaturated hydrocarbons and aliphatic unsaturated hydrocarbons such as vinyl chloride; aromatic unsaturated hydrocarbons such as styrene and α-methylstyrene; vinyl ethers; allyl alcohol and various organic acids Examples include esters; ethers of allyl alcohol and various alcohols; unsaturated cyanide compounds such as acrylonitrile; vinyl acetate and the like. These may be used alone or in combination of two or more, and is not limited. The other monomer (D) is preferably suppressed to within 10% by mass in 100% by mass of the raw material monomer component of the graft polymer. If it exceeds 10% by mass, the amount of the essential monomer components (A) to (C) decreases as a result, so that desired adhesive properties cannot be obtained.

[High Tg polymer structure]
The graft polymer of the present invention has a polymer structure having a Tg of 0 ° C. or more in the side chain (branch). Since a high Tg polymer structure having a Tg of 0 ° C. or higher is grafted to the side chain, deformation of the pressure-sensitive adhesive layer is suppressed and reduction of the adhesive force during high-speed peeling is achieved.

  The Tg of the polymer that becomes the side chain (hereinafter sometimes simply referred to as “branched polymer”) must be 0 ° C. or higher. However, in order to further improve the high-speed peelability, the Tg of the branched polymer is 5 degreeC or more is preferable. However, if the Tg of the branched polymer is too high, the adhesive force at the time of low-speed peeling may be insufficient, so that it is preferably 160 ° C. or lower, more preferably 80 ° C. or lower, and further preferably 40 ° C. or lower.

  Specific examples of monomers that can be used in the branched polymer include vinyl acetate (Tg of homopolymer (hereinafter the same) = 30.0 ° C.), methyl acrylate (Tg = 9.9 ° C.), acrylic acid (Tg = 105.9 ° C.). ), Methyl methacrylate (Tg = 104.9 ° C.), cyclohexyl methacrylate (Tg = 65.9 ° C.), benzyl acrylate (Tg = 6.0 ° C.), isobornyl acrylate (Tg = 94.0 ° C.), isoborn Nyl methacrylate (Tg = 145.0 ° C.), acrylonitrile (Tg = 95.0 ° C.), styrene (Tg = 100.0 ° C.) and the like can be mentioned. These may be used alone or in combination of two or more. Can do.

  Further, if the Tg of the copolymer calculated by the above formula is 0 ° C. or higher, various monomers exemplified as the monomers (A) to (D) may be used in combination when obtaining the branched polymer. .

  The molecular weight of the branched polymer is preferably about 15000 to 100,000 in terms of mass average molecular weight (Mw). This branched polymer forms a microdomain structure (fine island) in the pressure-sensitive adhesive layer. This suppresses deformation of the pressure-sensitive adhesive layer at the time of peeling, and can reduce the adhesive strength at the time of high-speed peeling. However, if the Mw of the branch polymer is too large, it becomes difficult to form a microdomain structure, and at the time of high-speed peeling. Adhesive strength reduction action decreases. Therefore, Mw is preferably within the above range, and more preferably 20,000 to 70,000.

  The mass of the branch polymer is preferably about 3 to 30% by mass of the entire graft polymer. Therefore, it is preferable that the content of the monomer for the branch polymer is 3 to 30% by mass in 100% by mass of the raw material monomer component of the graft polymer. 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. A more preferable amount of the monomer used for the branch polymer is 5 to 25% by mass.

  As a method for synthesizing a graft polymer, a macromonomer method, an ionic polymerization method, a method for introducing a branch polymer by a polymer reaction, and the like are known. In order to synthesize the graft polymer of the present invention, a macromonomer method that can easily control the molecular weight of the main chain polymer and the branch polymer, suppress homopolymer formation, and easily connect the main chain polymer to the branch polymer is suitable. Specifically, a method of synthesizing a graft polymer using a macromonomer (E) having a polymer structure having a Tg of 0 ° C. or higher is preferable.

  The macromonomer (E) is a monomer in which a radical polymerizable double bond is introduced at the end of the above branch polymer. There are various methods for synthesizing a macromonomer, and a functional group derived from a chain transfer agent is introduced into the end of the branched polymer by polymerizing a branch polymer using a chain transfer agent having a functional group. A method in which a monomer having a functional group capable of reacting with a radical polymerizable double bond is chemically reacted with the functional group at the end of the branched polymer 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 branch polymer.

  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 branch polymer via a chain transfer agent to obtain a macromonomer (E). 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 branch polymer may be referred to as a monomer (E ′) for the macromonomer (E).

  For the polymerization of the macromonomer (E) branch polymer, a known method may be used, and in particular, solution polymerization in which removal of polymerization heat is easy is preferable. 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.

  The reaction conditions such as the polymerization reaction temperature and reaction time are not particularly limited as long as the appropriate amount of the chain transfer agent is used, and may be appropriately set 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 peroxyoctate , T-butyl peroxybenzoate, organic peroxide such as trade name “Niper BMT-K40” (manufactured by NOF Corporation; mixture of m-toluoyl peroxide and benzoyl peroxide), and 2,2′-azobis Isobutyronitrile (manufactured by Nippon Finechem; “ABN-R”), 2,2′-azobis (2-methylbutyronitrile) (manufactured by Nippon Finechem; “ABN-E”), 2,2′-azobis (2,4-dimethylvaleronitrile) (Nippon Finechem Co., Ltd .; “ABN” V ") azo compounds such like.

  By the said method, the branch polymer which has the carboxyl group or hydroxyl group derived from the chain transfer agent used for the production | generation of a branch polymer in one terminal is obtained. After obtaining the branched polymer, the radical polymerization double bond is introduced continuously. The macromonomer (E) monomer (E ′) having reactivity with a carboxyl group or hydroxyl group at one end of the branched polymer is diluted, for example, directly into the branched polymer solution after polymerization or with a solvent or the like. What is necessary is just to add. Further, if necessary, a catalyst suitable for each reaction can be appropriately selected and used.

  For example, when synthesizing a branch polymer using a chain transfer agent having a carboxyl group and introducing a radical polymerizable double bond using the monomer (E ′) for the macromonomer (E) having a glycidyl group, An esterification catalyst can be used 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 addition, when a chain polymer having a hydroxyl group is used to synthesize a branch polymer and a radical polymerizable double bond is introduced using the monomer (E ′) for the macromonomer (E) having an isocyanate group, In order to accelerate the reaction, a known metal catalyst or amine catalyst can be used. Examples of metal catalysts include dibutyltin dilaurate, tin octoate, dibutyltin di (2-ethylhexanoate), 2-ethylhexanoate lead, 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.

  The reaction ratio is preferably 0.8 to 1 (molar ratio) with respect to the functional group derived from the chain transfer agent at the end of the branch polymer, such as a carboxyl group or a hydroxyl group.

  The macromonomer (E) is preferably about 3 to 30% by mass in 100% by mass of the raw material monomer component for obtaining the graft polymer. 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. A more preferable amount of the macromonomer (E) used is 5 to 25% by mass.

  In the most preferred embodiment of the graft polymer of the present invention, the monomer (A) is butyl acrylate and / or 2-ethylhexyl acrylate, the monomer (B) is methoxytriethylene glycol (meth) acrylate, or methoxypolyethylene glycol (meth) acrylate. And at least one selected from the group consisting of hydroxypolyethyleneglycol-3-methyl-3-butenyl, wherein the functional group-containing monomer (C) is 2-hydroxyethyl acrylate and / or 4-hydroxybutyl acrylate, (E) is a polymer obtained from a monomer component in which the polymer structure is polymethyl acrylate.

  The graft polymer can be obtained by a known polymerization method, and is preferably polymerized by a solution polymerization method in that a solvent-type re-peeling pressure-sensitive adhesive composition can be easily obtained. As the solvent used in the solution polymerization, any of the solvents exemplified in the polymerization of the branched polymer for the macromonomer (E) can be used. Although the solvent type re-peeling pressure-sensitive adhesive composition of the present invention contains a solvent as an essential component, it is preferable to use the same solvent as the polymerization solvent. What was obtained by completion | finish of superposition | polymerization can be used as a solvent-type re-peeling adhesive composition raw material as it is.

  Reaction conditions such as polymerization reaction temperature and reaction time may be appropriately set according to, for example, the composition and amount of the monomer, and are not particularly limited. 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. As the polymerization catalyst (polymerization initiator), any of the initiators exemplified when grafting the branched polymer can be used. In the polymerization of the graft polymer, it is not necessary to use a functional group-containing chain transfer agent, and therefore known molecular weight regulators represented by mercaptans such as dodecyl mercaptan can be used.

  The graft polymer preferably has a mass average molecular weight (Mw) of 100,000 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 100,000, there is a possibility that the adhesive strength after heat treatment may increase, 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 120,000 to 600,000.

  The Tg of the graft polymer is low even if the Tg of the branched polymer is 0 ° C. or higher because the Tg of the polymer constituting the main chain is low. Specifically, −20 ° C. or lower is preferable, and −35 ° C. or lower is more preferable. However, Tg lower than −80 ° C. is not preferable because the cohesive force tends to decrease and adherend contamination tends to occur.

[Mixture type]
In the solvent-type re-peeling pressure-sensitive adhesive composition of the present invention, in addition to the type using the graft polymer as a pressure-sensitive adhesive polymer, a high Tg polymer and an alkylene oxide polymer for expressing adhesive force are mixed, There are mixture types that form an adhesive polymer. The alkylene oxide polymer is a monomer other than the macromonomer (E) in synthesizing the main chain polymer of the graft polymer, that is, an alkyl (meth) acrylate monomer (A), an alkylene oxide chain-containing monomer (B), and a functional group It synthesize | combines from the raw material monomer component which consists of a monomer (C) and another monomer (D) as needed. The preferred embodiment is the same as that for the graft polymer.

  The ratio of the alkyl (meth) acrylate monomer (A), the alkylene oxide chain-containing monomer (B), the functional group-containing monomer (C) and the other monomer (D) used as necessary is 100% by mass of the raw material monomer component. It is preferable that (A) is 35 to 85% by mass, (B) is 5 to 65% by mass, (C) is 0.3 to 8% by mass, and (D) is 0 to 10% by mass.

  As the high Tg polymer, the same type of monomer as that of the above-mentioned graft polymer can be used, and the preferred embodiment is the same as that of the branch polymer. However, since it is not necessary to modify the macromonomer (E), it is not necessary to use a functional group-containing chain transfer agent and it is not necessary to react the monomer for macromonomer (E ′). It may be used as a polymer.

  The high Tg polymer and the alkylene oxide polymer are incompatible with each other because the Tg is different and the compositions are different. However, the high Tg polymer and the alkylene oxide polymer adopt a sea-island structure and exhibit without impairing the action effect of each polymer. In the present invention, a high Tg polymer is dispersed as islands to suppress an increase in adhesive force during high speed peeling. The high Tg polymer is required to be 3% by mass or more, and if it is less than this, the above effect will be insufficient. More preferably, it is 4 mass% or more, More preferably, it is 5 mass% or more. However, if the amount is too large, the low-speed adhesive strength and the conformability are reduced, so the content is preferably 30% by mass or less, and more preferably 20% by mass or less.

  The above graft polymer may be used as an alkylene oxide polymer and mixed with a high Tg polymer to form a mixture type.

[Metal salt compounds]
In the following description, when the graft polymer is used alone as the pressure-sensitive adhesive polymer, both of the case where the high Tg polymer and the alkylene oxide polymer are used as the pressure-sensitive adhesive polymer are collectively referred to as the pressure-sensitive adhesive polymer.

  The solvent-type re-peeling pressure-sensitive adhesive composition of the present invention contains a metal salt compound. The metal salt compound is dissociated into metal ions by the action of alkylene oxide in the pressure-sensitive adhesive layer. Since this metal ion can move through the alkylene oxide chain, the pressure-sensitive adhesive layer becomes conductive and exhibits antistatic ability.

Examples of the metal salt compound include one kind of cation selected from alkali metals such as lithium, sodium and potassium, and alkaline earth metals such as magnesium, halogen ions such as chlorine ions and iodine ions, perchlorate ions, thiocyanates. Examples thereof include inorganic salts composed of one kind of anions such as acid ions, trifluoromethanesulfonate ions, and toluenesulfonate ions; organic salts such as lithium stearylsulfonate; quaternary ammonium salts; and the like. Of these ionic compounds, lithium salts are particularly preferred because they have a relatively low energy during ion dissociation and high mobility in a solvent described later. Specific examples of the compound include LiBr, LiI, LiClO ₄ , LiSCN, LiCF ₃ SO _{3 and the} like.

  It is preferable that a metal salt compound shall be 0.1-10 mass parts with respect to 100 mass parts of adhesive polymers. If the amount is too small, the antistatic ability of the pressure-sensitive adhesive layer may be insufficient. When there are too many metal salt compounds, there exists a possibility of depositing and contaminating a to-be-adhered body, it is unpreferable.

  A conventionally known organic antistatic agent can also be used in combination. For example, a cation type antistatic agent having a cationic functional group such as quaternary ammonium salt, pyridinium salt, primary, secondary or tertiary amino group; sulfonate, sulfate ester, phosphonate, phosphate ester Anionic antistatic agent having an anionic functional group such as salt; amphoteric antistatic agent such as alkylbetaine and derivatives thereof, imidazoline and derivatives thereof, alanine and derivatives thereof; amino alcohol and derivatives thereof, glycerin and derivatives thereof, polyethylene Nonionic antistatic agents such as glycol and derivatives thereof; ion conductive polymers obtained by (co) polymerizing these cationic, anionic and zwitterionic ion-conducting monomers. . These antistatic agents may be used alone or in combination of two or more.

[Crosslinking agent]
In addition to the pressure-sensitive adhesive polymer, the pressure-sensitive adhesive composition of the present invention preferably contains a crosslinking agent in order to control the cohesive force and the crosslinking density. As a crosslinking agent, the compound which has 2 or more of functional groups which can react with the functional group which a functional group containing monomer (C) has in 1 molecule is used. For example, if the pressure-sensitive adhesive polymer has a hydroxyl group as a result of using a hydroxyl group-containing monomer as the functional group-containing monomer (C), a polyfunctional isocyanate compound having two or more isocyanate groups in one molecule is preferable. . Moreover, if the adhesive polymer has a carboxyl group, a polyfunctional isocyanate compound, a polyfunctional epoxy compound, etc. are preferable. From the viewpoint of reactivity, a combination of a hydroxyl group and a polyfunctional isocyanate compound is most preferable.

  Examples of the polyfunctional isocyanate compound include aromatic polyisocyanates such as xylylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, and tolylene diisocyanate; hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated products of the above aromatic polyisocyanates, and the like. Aliphatic or alicyclic polyisocyanates; dimers or trimers of these polyisocyanates; adducts composed of these polyisocyanates and polyols such as trimethylolpropane, and the like.

  More specifically, for example, “Coronate L-55E”, “Coronate HX”, “Coronate HL-S”, “Coronate 2234”, “Aquanate 200”, “Aquanate 210” (all of which are Nippon Polyurethane) “Coronate” and “Aquanate” are registered trademarks); “Desmodule N3400” (manufactured by Sumitomo Bayer Urethane (currently Bayer AG); “Desmodule” is a registered trademark); -201 "," Duranate E-405-80T "," Duranate 24A-100 "," Duranate TSE-100 "(all manufactured by Asahi Kasei Corporation;" Duranate "is a registered trademark);" Takenate D-110N "," Takenate D-120N ”,“ Takenate M-631N ”,“ MT-Olestar NP1200 ”(Mitsui Made Gakusha; "Takenate", "I Star" are commercially available and is a registered trademark), etc., it is available. These can be used alone or in combination of two or more.

  Among these, a modified burette of hexamethylene diisocyanate (HMDI) (trifunctional; for example, “Duranate 24A-100” (manufactured by Asahi Kasei Co., Ltd.)) has a high-speed release property, a conformability, and an adhesive strength at low-speed release. This is particularly preferable in terms of the balance of the two characteristics. Moreover, “Duranate TSE-100” and “Coronate L-55E”, which is an adduct of tolylene diisocyanate and trimethylolpropane, are also suitable in that they can control the high-speed release property and the adhesive force at the time of low-speed release in a balanced manner. It is.

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

  These crosslinking agents are preferably added so as to be 0.1 to 2.5 equivalents when the total of the functional groups of the pressure-sensitive adhesive polymer is 1 equivalent. When the amount of the cross-linking agent is less than 0.1 equivalent, the cohesive force is insufficient and the high-speed peel adhesive force may become too large. On the other hand, if it exceeds 2.5 equivalents, the conformability (wettability) is extremely lowered, which is not preferable. A more preferable amount of the crosslinking agent is 0.3 to 2 equivalents.

[Solvent-type re-peeling pressure-sensitive adhesive composition]
The non-volatile content of the pressure-sensitive adhesive composition for solvent-type re-peeling of the present invention is not particularly limited, but is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, and still more preferably 25 to 25%. 60% by mass. In particular, in coating, it is preferable from the viewpoint of coating work to adjust the non-volatile content to 20 to 50% by mass. 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.

  Addition of known crosslinking accelerators, tackifiers, modifiers, pigments, colorants, fillers, anti-aging agents, UV absorbers, UV stabilizers, antistatic agents, etc. to the pressure-sensitive adhesive composition of the present invention An agent may be added as long as the object of the present invention is not impaired.

[Removable adhesive products]
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) in which an adhesive layer is formed on one side of a substrate by applying the adhesive composition on the substrate or release paper and forming a dry coating film thereof, the substrate A pressure-sensitive adhesive product having a pressure-sensitive adhesive layer formed on both sides thereof, or a pressure-sensitive adhesive product having only a pressure-sensitive adhesive layer having no 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 substrate is preferably a transparent film such as polyethylene terephthalate. In general, the thickness of the substrate is preferably 200 μm or less, more preferably 5 to 100 μm, and still more preferably about 10 to 50 μm. An antistatic layer may be provided on one side or both sides of these base materials in order to prevent charging during peeling. Moreover, in order to improve adhesiveness with an adhesive layer, you may perform well-known easy adhesion processing, such as a corona discharge process, to an adhesive layer formation surface.

  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

[Adhesive properties of adhesive layer]
The pressure-sensitive adhesive composition of the present invention produced a pressure-sensitive adhesive product in which a pressure-sensitive adhesive layer having a thickness of 20 μm obtained from this pressure-sensitive adhesive composition was formed on a polyethylene terephthalate film substrate having a thickness of 38 μm. When the 180 ° adhesive strength to an acrylic plate at 65 ° C. and a relative humidity of 65% is measured, the 180 ° adhesive strength at 23 ° C. is preferably 1.6 N / 25 mm or less at a peeling speed of 30 m / min (high speed peeling). 1.2 N / mm or less is more preferable. Further, the value obtained by dividing the adhesive force in high-speed peeling by the adhesive force in low-speed peeling at a peeling speed of 0.3 m / min is preferably 18.0 or less. In the unit “N / 25 mm”, the portion “/ 25 mm” means the width of the pressure-sensitive adhesive sheet bonded to the adherend.

  In addition, the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive product produced in the same manner as described above, and a 4 cm square sample is cut out and placed on an adherend having a surface with an uneven height difference of 5 to 6 μm. In addition, the time until the entire surface of the sample gets wet with respect to the adherend (familiar time) is preferably 60 seconds or less, and more preferably 45 seconds or less. This is because the shorter the time until conforming, the better the conformability. In measuring the conforming time, before placing the sample on the adherend, about 1 to 2 mm from one side of the sample is attached to the adherend by hand in advance, and the conforming time is measured. Here, “the entire surface of the sample is wet” refers to a state in which the air existing between the adhesive product sample and the adherend surface is released and the sample is in close contact with the unevenness of the adherend surface. Specifically, when the adhesive product sample comes into close contact with the adherend surface as the air escapes, the sample can be seen through, so that the contact state can be visually observed. The uneven height difference is expressed as the distance between the top of the maximum peak and the bottom of the maximum valley when the surface of the adherend is analyzed by, for example, a laser microscope.

  Since the adhesive product for re-peeling of the present invention may be used for a surface protective film for optical members, an anti-glare film that is a representative example of a film that is difficult to adapt among optical members as an adherend used in the measurement of the familiar time. Is preferably used. The anti-glare film is provided in order to improve the visibility by suppressing the reflection of light emitted from an external light source such as a fluorescent lamp in image display such as a liquid crystal display (LCD) or a cathode ray tube display (CRT). It is a film. For this reason, fine irregularities are formed on the surface of the anti-glare film, which diffuses the reflected light and prevents the viewer from feeling dazzling. An anti-glare film is usually obtained by applying a coating liquid in which a light-transmitting diffusing agent such as silica or resin beads is dispersed in a binder resin to the surface of a transparent substrate such as PET and then curing it with heat, UV, or the like. It is manufactured. The surface roughness (Ra) is about 0.05 to 0.4 μm.

[Antistatic performance of adhesive layer]
The surface resistivity of the pressure-sensitive adhesive layer is preferably less than 10 ¹³ Ω. More preferably, it is 10 ¹² Ω or less. The surface resistivity can be measured by using a surface resistance meter or the like. A specific measurement method will be described later.

  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. In the following description, “%” indicates “mass%” and “part” indicates “part by mass” unless otherwise specified.

Moreover, Tg shown in each synthesis example is Tg calculated by the calculation formula. The following values were used for the Tg of the homopolymer of each monomer.
Poly (MA): 9.9 ° C
Poly (MMA): 104.9 ° C
Poly (VAc): 30.0 ° C
Poly (2EHA): -70.0 ° C
Poly (BA): -54.2 ° C
Poly (MTG-A): -50.0 ° C
Poly (AM90G): -30 ° C
Poly (HEGMB): -30 ° C
Poly (HEA): -15.0 ° C
Poly (4HBA): -32.0 ° C

Synthesis Example 1 (Synthesis of Macromonomer (E1))
First, polymethyl acrylate (PMA) to be a branch polymer was synthesized. 280 parts of methyl acrylate (MA), 0.9 part of 2-mercaptoethanol as chain transfer agent, 512 parts of ethyl acetate as solvent, equipped with thermometer, stirrer, inert gas introduction tube, reflux condenser and dropping funnel Added to the flask. Under stirring, the temperature of the flask was raised to 80 ° C. while flowing nitrogen gas, and “ABN-R” (manufactured by Nihon Finechem; 2,2′-) diluted with 13.9 parts of ethyl acetate as a polymerization initiator. 0.14 parts of azobisisobutyronitrile) was charged into the flask to initiate polymerization.

  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-R” and 56 parts of ethyl acetate was dropped into the flask over 1 hour 30 minutes. did. After completion of dropping, 112 parts of ethyl acetate was added while washing the dropping funnel. Thereafter, aging was carried out at 80 ° C. for 2 hours and 50 minutes to complete the reaction.

  Next, a radical polymerizable double bond introduction reaction with respect to the PMA was performed. 1400 parts of the above PMA solution, 3.99 parts of “Karenz MOI (registered trademark)” (manufactured by Showa Denko KK; 2-isocyanatoethyl methacrylate), “ANTAGE-W400” (manufactured by Kawaguchi Chemical Industry Co., Ltd .; 2, 0.42 part of 2′-methylenebis (4-methyl-6-tert-butylphenol), 42 parts of ethyl acetate as a diluting / washing solvent, equipped with a thermometer, a stirrer, a gas introduction tube, a reflux condenser and a dropping funnel While stirring, a mixed gas of nitrogen gas and oxygen gas was bubbled to raise the internal temperature of the flask to 70 ° C., and 0.98 parts of dibutyltin dilaurate diluted with 14 parts of ethyl acetate as a reaction catalyst was added. The addition reaction was started, and the addition reaction was carried out for 4 hours while maintaining the internal temperature of the flask at 70 ° C. to complete the reaction. Black monomer (E1) solution nonvolatile concentration of 45.8 percent, Mw is the method of measuring .Mw was 45,000 later. Tg of the macromonomer (E1) is 10 ° C..

Synthesis Example 2 (Synthesis of macromonomer (E2))
A macromonomer (E2) was synthesized in the same manner as in Synthesis Example 1 except that the monomer composition of the branched polymer was changed to 280 parts of MA and 420 parts of methyl methacrylate (MMA). The resulting macromonomer (E2) solution had a nonvolatile content concentration of 46.0% and Mw of 49,000. The macromonomer (E2) has a Tg of 60 ° C.

Synthesis Example 3 (Synthesis of macromonomer (E3))
The monomer composition of the branched polymer was changed to 700 parts of vinyl acetate (VAc), and "Karenz MOI" was changed to 3.63 parts of "Karenz AOI (registered trademark)" (Showa Denko KK; 2-isocyanatoethyl acrylate). Except for the above, a macromonomer (E3) was synthesized in the same manner as in Synthesis Example 1. The resulting macromonomer (E3) solution had a nonvolatile content concentration of 43.0% and Mw of 35,000. This macromonomer (E3) has a Tg of 30 ° C.

Synthesis Example 4 (Synthesis of macromonomer (E4))
A macromonomer (E4) was synthesized in the same manner as in Synthesis Example 3 except that the monomer composition of the branched polymer was changed to 280 parts of ethyl acrylate (EA) and 420 parts of MMA. The resulting macromonomer (E4) solution had a nonvolatile content concentration of 45.5% and Mw of 52,000. The macromonomer (E4) has a Tg of 40 ° C.

Synthesis Example 5 (Synthesis of pressure-sensitive adhesive polymer 1)
In a flask equipped with a thermometer, a stirrer, an inert gas introduction tube, a reflux condenser and a dropping funnel, the macromonomer (E1) is 80 parts in terms of non-volatile content and 208 parts of 2-ethylhexyl acrylate (2EHA) as the monomer (A) And 20 parts of n-butyl acrylate (BA), “MTG-A” as a monomer (B) (manufactured by Kyoeisha Chemical Co .; methoxypolyethylene glycol acrylate; in formula (2), R ″, R and R ′ are all H, R ² is a methyl group, n is 3) 160 parts, monomer (C) is 12 parts of 2-hydroxyethyl acrylate (HEA), chain transfer agent is n-dodecyl mercaptan (nDM) 0.4 part, These were mixed well with 328 parts of ethyl acetate and added, and the internal temperature of the flask was raised to 89 ° C. while flowing nitrogen gas with stirring. "ABN-E" (manufactured by Nippon Finechem Co., Ltd .; 0.08 part of 2,2'-azobis (2-methylbutyronitrile) diluted with 4 parts of ethyl acetate as a polymerization initiator was charged into the flask and polymerized. Was started.

  One hour after the start of the reaction, 0.04 part of “ABN-E” diluted with 4 parts of ethyl acetate was added as a polymerization initiator. From 3 to 4 hours after the start of the reaction, 1.2 parts of “ABN-R” diluted with 36.8 parts of ethyl acetate was added in three portions as a booster (post-initiator). . Thereafter, it was further aged at 78 ° C. for 2 hours. The resulting solution of the pressure-sensitive adhesive polymer 1 had a nonvolatile content concentration of 46.2% and Mw of 254,000. The Tg of this pressure-sensitive adhesive polymer 1 is −60 ° C.

Synthesis Example 6 (Synthesis of pressure-sensitive adhesive polymer 2)
Among the monomers initially charged in the flask, the macromonomer (E1) is changed to the macromonomer (E2), 2EHA 128 parts and BA 20 parts as the monomer (A), 240 parts "MTG-A" as the monomer (B), chain transfer agent The adhesive polymer 2 was synthesized in the same manner as in Synthesis Example 5 except that 0.5 part of nDM was used. The solution of the obtained adhesive polymer 2 had a nonvolatile content concentration of 46.0% and Mw of 23,000. This adhesive polymer 2 has a Tg of −60 ° C.

Synthesis Example 7 (Synthesis of pressure-sensitive adhesive polymer 3)
Among the monomers initially charged in the flask, the macromonomer (E1) is changed to the macromonomer (E3), 2EHA 125.2 parts and BA 20 parts as the monomer (A), “MTG-A” 240 parts as the monomer (B), monomer Adhesive polymer 3 was synthesized in the same manner as in Synthesis Example 5 except that 14.8 parts of 4-hydroxybutyl acrylate (4HBA) was used as (C) and 0.5 parts of nDM was used as the chain transfer agent. The solution of the obtained adhesive polymer 3 had a nonvolatile content concentration of 45.9% and Mw of 24,000,000. The Tg of this pressure-sensitive adhesive polymer 3 is −60 ° C.

Synthesis Example 8 (Synthesis of pressure-sensitive adhesive polymer 4)
The adhesive polymer 4 was synthesized in the same manner as in Synthesis Example 6 except that the macromonomer (E1) was changed to the macromonomer (E4) among the monomers initially charged in the flask. The solution of the obtained adhesive polymer 4 had a nonvolatile content concentration of 46.4% and Mw of 262,000. This adhesive polymer 4 has a Tg of −60 ° C.

Synthesis Example 9 (Synthesis of pressure-sensitive adhesive polymer 5)
Among the monomers initially charged in the flask, the macromonomer (E1) is 120 parts in terms of nonvolatile content, 128 parts of 2EHA and 20 parts of BA as the monomer (A), 240 parts of “MTG-A” as the monomer (B), and nDM0 as the chain transfer agent The pressure-sensitive adhesive polymer 5 was synthesized in the same manner as in Synthesis Example 5 except that 6 parts were used. The solution of the obtained adhesive polymer 5 had a nonvolatile content concentration of 46.0% and Mw of 145,000. This adhesive polymer 5 has a Tg of −56 ° C.

Synthesis Example 10 (Synthesis of pressure-sensitive adhesive polymer 6)
Among the monomers initially charged in the flask, 200 parts of “MTG-A” and “AM90G” (manufactured by Shin-Nakamura Chemical Co., Ltd .; methoxypolyethylene glycol acrylate; R (2), R ″, R, R ′) as monomers (B) Are H, R ² is a methyl group, and n is 9) except that 40 parts were used, and a pressure-sensitive adhesive polymer 6 was synthesized in the same manner as in Synthesis Example 5. The solution of the resulting pressure-sensitive adhesive polymer 6 was non-volatile. The partial concentration was 46.3% and the Mw was 135,000. The Tg of this pressure-sensitive adhesive polymer 6 was -54 ° C.

Synthesis Example 11 (Synthesis of pressure-sensitive adhesive polymer 7)
Among the monomers initially charged in the flask, 200 parts of “MTG-A” and hydroxypolyethyleneglycol-3-methyl-3-butenyl (in formula (1), R ¹ is (ix), R, R The pressure-sensitive adhesive polymer 7 was synthesized in the same manner as in Synthesis Example 5 except that 40 parts of 'and R ² were H, n was 10; HEGMB). The solution of the obtained pressure-sensitive adhesive polymer 7 had a nonvolatile content concentration of 45.8% and Mw of 12.8 million. The adhesive polymer 7 has a Tg of −54 ° C.

Synthesis Example 12 (Synthesis of pressure-sensitive adhesive polymer 8)
Of the monomers initially charged in the flask, the macromonomer (E2) was 120 parts in a non-volatile content, the monomer (A) was 368 parts and BA 20 parts, the monomer (B) was not used, and nDM 0.15 part was used as a chain transfer agent. Except for the above, an adhesive polymer 8 was synthesized in the same manner as in Synthesis Example 9. The solution of the obtained pressure-sensitive adhesive polymer 8 had a nonvolatile content concentration of 46.6% and Mw of 1490,000. This adhesive polymer 8 has a Tg of −68 ° C.

Synthesis Example 13 (Synthesis of pressure-sensitive adhesive polymer 9)
In a flask equipped with a thermometer, stirrer, inert gas introduction tube, reflux condenser and dropping funnel, 208 parts of 2EHA and 20 parts of BA as monomer (A), 160 parts of “MTG-A” as monomer (B), monomer ( As C), 12 parts of HEA was used, 0.07 part of nDM was used as a chain transfer agent, and these were mixed well with 384 parts of ethyl acetate and added. Macromonomer (E) was not used. While stirring the nitrogen gas, raise the internal temperature of the flask to 92 ° C., and add 0.1 part of “ABN-E” diluted with 0.9 part of ethyl acetate as a polymerization initiator to the flask. Polymerization was started.

  One hour after the start of the reaction, 0.2 part of “ABN-E” diluted with 1.8 parts of ethyl acetate was added as a polymerization initiator. From 3.5 hours to 5 hours after the start of the reaction, “ABN-V” (manufactured by Nippon Finechem Co., Ltd .; 2,2′-azobis (2,4- Dimethylvaleronitrile) 0.8 parts was added in 4 portions, and then further aged for 2 hours at 78 ° C. The solution of the resulting adhesive polymer 9 had a nonvolatile content concentration of 48.9% and Mw was The pressure-sensitive adhesive polymer 9 has a Tg of −60 ° C.

Synthesis Example 14 (Preparation of pressure-sensitive adhesive polymer (mixture type) 10)
20 parts of the non-volatile content of the macromonomer (E3) was added to 100 parts of the non-volatile content of the pressure-sensitive adhesive polymer 9, and the mixture was sufficiently stirred to obtain a pressure-sensitive adhesive polymer 10. The Tg of the pressure-sensitive adhesive polymer 10 is −60 ° C.

Experimental example [Characteristic evaluation]
Tables 1 and 2 also show the polymer properties in each example and the results of the property evaluation using the pressure-sensitive adhesive polymer solution. The characteristic evaluation method is as follows.

[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%

[Preparation of adhesive composition and production of adhesive product (test tape)]
About the adhesive polymer solution obtained by each synthesis example, the non volatile matter was prepared to 34% with ethyl acetate. Table 1 shows 250 ppm (mass basis) of dibutyltin dilaurate as a cross-linking accelerator and 100 units of duranate (registered trademark) 24A-100 (hexamethylene diisocyanate bullet modified product; trifunctional; manufactured by Asahi Kasei Co., Ltd.) per 100 parts of polymer. In addition, the metal salt compounds of the types and amounts shown in the table were added so that the equivalent amount was obtained, and the whole was well stirred to obtain a pressure-sensitive adhesive composition.

  A polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc .; thickness 38 μm) is used as a supporting substrate, and the pressure-sensitive adhesive composition is applied so that the thickness after drying is 20 μm, and then dried at 100 ° C. for 2 minutes. Thus, an adhesive film was prepared. After sticking and protecting the PET film which gave the mold release process on the adhesive surface, it was cured for one week in an atmosphere at 23 ° C. The pressure-sensitive adhesive film after curing was conditioned for 24 hours in an atmosphere of 23 ° C. and a relative humidity of 65%, and then cut into an appropriate length with a width of 25 mm to prepare a test tape. The release film was peeled off during the test.

[Peeling adhesive strength]
The test tape is reciprocated once with a 2 kg rubber roller on a 3 mm thick acrylic plate (standard test plate manufactured by Nippon Test Panel Co., Ltd.) in an atmosphere of 23 ° C. and 65% relative humidity. After leaving for 24 hours after pressure bonding, the peeling speed was 0.3 m / min for low speed peeling and 30 m / min for high speed peeling, and 180 ° peeling adhesive strength was measured in an atmosphere of 23 ° C. according to JIS K 6854. . The table also shows the evaluation result of the high-speed peel adhesive strength and the evaluation result of the value obtained by dividing the high-speed peel adhesive strength by the low-speed peel adhesive strength (shown as “high speed / low speed”).

  In the case of the high-speed peel adhesive strength, the evaluation criteria were 1.6 N / 25 mm or less as ◯ and those exceeding 1.6 N / 25 mm as x. In the case of “high speed / low speed” (peeling speed dependence), 15 or less was marked with ◎, more than 15 and 18 or less with ◯, and more than 18 with x.

[Familiarity]
A test piece having a size of 4 cm × 4 cm is cut out from the test tape. The 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 value by “VK-9710” manufactured by Keyence Corporation) is adhered. And place the anti-glare film horizontally on a flat surface with the rough side facing 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 begins to get wet to the film until the entire test piece is fully adapted to the film is measured. Conformability is: ◎ if the entire test piece fits within 30 seconds, ○ if over 30 seconds but fit within 60 seconds, △ if over 60 seconds but within 120 seconds △ Those exceeding 120 seconds were evaluated as x.

[Surface resistivity (Ω)]
The surface resistivity of the pressure-sensitive adhesive layer was measured using “Digital Super Insulation / Micro Ammeter: DSM-8104” manufactured by Hioki Electric Co., Ltd. and an optional plate sample electrode “SME-883”. A sample was cut out from the test tape into a size of 5 cm × 5 cm. The measurement atmosphere was 23 ° C. and relative humidity 65%. The surface resistivity of the adhesive layer is less than 10 ¹² Ω ◎, less than 10 ¹² Omega than 10 ¹³ Ω ○, were evaluated over 10 ¹³ Omega as ×.

  In all of the examples of the present invention, it was confirmed that the adhesive strength at high speed peeling, high speed / low speed, good conformability, excellent adhesive properties in a well-balanced manner, and low surface resistivity. .

  Since the comparative example 1 did not add the metal salt compound, the surface resistivity is large. In Comparative Example 2, since “MTG-A” as the monomer (B) was not copolymerized, the conformability and the surface resistivity were inferior. In Comparative Example 3, since the macromonomer was not copolymerized, the pressure-sensitive adhesive polymer did not have a high Tg polymer structure. Therefore, the adhesive strength at the time of high-speed peeling was large, and the high-speed / low-speed was inferior.

  The pressure-sensitive adhesive polymer used in the present invention uses a pressure-sensitive adhesive polymer having a polymer structure having a glass transition temperature (Tg) of 0 ° C. or more and a polymer structure capable of improving adhesive properties and conformability. It was possible to provide a pressure-sensitive adhesive composition for re-peeling capable of forming a pressure-sensitive adhesive layer having excellent adhesive strength at low speed and conformability to an adherend. Moreover, since the metal salt compound was blended, the antistatic ability of the pressure-sensitive adhesive layer was improved. Accordingly, the pressure-sensitive adhesive product obtained using the pressure-sensitive adhesive composition has a surface of an optical member such as an optical polarizing plate (TAC), a retardation plate, an EMI (electromagnetic wave) shield film, an antiglare film, an antireflection film, or the like. It can be used as an adhesive product for re-peeling to protect. It can also be used as a protective film for the surface of other plastics and metal plates.

Claims (8)

A pressure-sensitive adhesive composition for solvent-type re-peeling containing a pressure-sensitive adhesive polymer, the pressure-sensitive adhesive polymer having a high Tg polymer structure having a glass transition temperature of 0 ° C. or higher and an alkyl group having 4 to 12 carbon atoms. An alkylene oxide polymer structure synthesized from a raw material monomer component containing an alkyl (meth) acrylate (A), an alkylene oxide chain-containing monomer (B) and a functional group-containing monomer (C) as essential components, and a metal salt compound Blended,
The pressure-sensitive adhesive polymer, Ri graft polymer der with the high Tg polymer structure in a side chain,
The solvent-type re-peeling pressure-sensitive adhesive composition, wherein the raw material monomer having a high Tg polymer structure is 3 to 30% by mass in 100% by mass of the raw material monomer component of the pressure-sensitive adhesive polymer . The solvent-based re-peeling pressure-sensitive adhesive composition according to claim 1, wherein the graft polymer is a copolymer of the macromonomer (E) having the high Tg polymer structure.   In 100% by mass of the raw material monomer component of the graft polymer, the alkyl (meth) acrylate (A) is 25 to 85% by mass, the alkylene oxide chain-containing monomer (B) is 5 to 70% by mass, the functional group-containing monomer ( The solvent type re-peeling pressure-sensitive adhesive according to claim 2, wherein C) is 0.3 to 8% by mass, the other monomer (D) is 0 to 10% by mass, and the macromonomer (E) is 3 to 30% by mass. Agent composition. The solvent-type re-peeling pressure-sensitive adhesive composition according to claim 1, wherein the alkylene oxide chain-containing monomer is a monomer represented by the following formula (1).
[In the formula (1), R ¹ is an alkenyl group having 2 to 5 carbon atoms, and R and R ′ are either a hydrogen atom and one is a methyl group, or both are hydrogen atoms, R ² is a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and n is an added mole number of alkylene oxide, which is 1 to 50. ] Prepare a pressure-sensitive adhesive products in which a pressure-sensitive adhesive layer of claim 1 Thickness 20μm obtained from solvent-removable pressure-sensitive adhesive composition described in any one of 4 is formed on a polyethylene terephthalate film substrate having a thickness of 38μm When the adhesive strength of this adhesive product at 180 ° to an acrylic plate at 23 ° C. and relative humidity of 65% was measured, it was 1.6 N / 25 mm or less at a high speed peeling of 30 m / min. The solvent type according to any one of claims 1 to 4 , wherein a value obtained by dividing by an adhesive force at a low speed peeling of 3 m / min is 18.0 or less, and a surface resistivity of the adhesive layer is less than 10 ¹³ Ω. Re-peeling pressure-sensitive adhesive composition. When a 4 cm square sample is cut out from the adhesive product and placed on an adherend having a surface with an uneven height difference of 5 to 6 μm, the entire surface of the sample becomes wet with respect to the adherend. solvent-removable pressure-sensitive adhesive composition according to any one of claims 1 to 5 times of 60 seconds or less. 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 any one of claims 1 to 6 is formed on at least one surface of a support substrate. The adhesive product for re-peeling according to claim 7 , which is used for a surface protective film for an optical member.