JP6892803B2 - Adhesive composition - Google Patents

Description

The present invention relates to an adhesive composition containing an acrylic block copolymer suitable for an adhesive or the like.

It has been conventionally known to use an acrylic block copolymer or a composition containing an acrylic block copolymer as an adhesive.
For example, a methacrylic acid alkyl ester-based polymer having a glass transition temperature of 110 ° C. or higher and syndiotacticity of 70% or higher at both ends of a (meth) acrylic acid alkyl ester-based polymer block having a glass transition temperature of 30 ° C. or lower. A block copolymer composition containing a block-bonded triblock copolymer, a (meth) acrylic acid alkyl ester-based diblock copolymer, and a pressure-sensitive adhesive comprising the composition are known (Patent Document 1). reference). Further, a pressure-sensitive adhesive composition containing a specific diblock copolymer composed of a methacrylic acid alkyl ester-based polymer block and an acrylic acid alkyl ester-based polymer block and a (meth) acrylic acid ester-based triblock copolymer is known. (See Patent Document 2). Further, a pressure-sensitive adhesive composition containing a triblock copolymer composed of a specific methacrylic acid alkyl ester-based polymer block and an acrylic acid alkyl ester-based polymer block and a diblock copolymer is known (Patent Document 3). reference).

Japanese Unexamined Patent Publication No. 11-323072 Japanese Unexamined Patent Publication No. 2004-002736 Japanese Unexamined Patent Publication No. 2005-307063

The pressure-imparting resins and plasticizers specifically studied in the pressure-sensitive adhesives and pressure-sensitive adhesive compositions described in the above patent documents are limited, and there is still room for improvement in transparency, bleed resistance, adhesive properties, and the like. is there. An object of the present invention is to provide an adhesive composition containing an acrylic block copolymer having excellent transparency, bleed resistance, and adhesive properties.

As a result of diligent studies to achieve the above object, the present inventors have made an adhesive composition containing a specific acrylic triblock copolymer and a specific tackifier resin in a specific blending ratio. It has been found that a viscous adhesive composition containing an acrylic block copolymer having excellent transparency, bleed resistance, adhesive properties and the like can be obtained.

According to the present invention, the above object is
[1] (i) It has two polymer blocks (A1) and (A2) composed of methacrylic acid ester units and one polymer block (B) composed of acrylic acid ester units, and (A1)-(B). )-(A2) Acrylic having a block structure, a weight average molecular weight (Mw) of 50,000 to 250,000, and a total content of the polymer blocks (A1) and (A2) of 35% by mass or less. A viscous adhesive composition containing 100 parts by mass of the system triblock copolymer (I) and 1 to 190 parts by mass of the tackifier resin (ii).
[2] (i) It has two polymer blocks (A1) and (A2) composed of methacrylic acid ester units and one polymer block (B) composed of acrylic acid ester units, and (A1)-(B). )-(A2) Acrylic having a block structure, a weight average molecular weight (Mw) of 50,000 to 250,000, and a total content of the polymer blocks (A1) and (A2) of 35% by mass or less. Adhesive composition containing 100 parts by mass of the system triblock copolymer (I), 1 to 190 parts by mass of the tackifier resin (ii), and 80 parts by mass or less of the plasticizer (iii);
Is achieved by providing.

According to the present invention, an adhesive composition containing an acrylic block copolymer having excellent transparency, bleed resistance, adhesive properties and the like can be obtained.

Hereinafter, the present invention will be described in detail. In the present specification, "(meth) acrylic acid ester" is a general term for "methacrylic acid ester" and "acrylic acid ester", and "(meth) acrylic" is a general term for "methacrylic acid" and "acrylic". It is a generic term.

(Acrylic triblock copolymer (I))
The acrylic triblock copolymer (I) contained in the adhesive composition of the present invention is composed of two polymer blocks (A1) and (A2) composed of methacrylic acid ester units and an acrylic acid ester unit. It has one polymer block (B), has a (A1)-(B)-(A2) block structure, has a weight average molecular weight (Mw) of 50,000 to 250,000, and has a polymer block (A1)-(B)-(A2). The total content of A1) and (A2) is 35% by mass or less.

(Polymer blocks (A1) and (A2))
The acrylic triblock copolymer (I) has a polymer block composed of methacrylic acid ester units (A1) and a polymer block composed of two methacrylic acid ester units (A2).

Examples of the methacrylic acid ester that is a constituent unit of the polymer blocks (A1) and (A2) include methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, and methacrylic acid. Isobutyl, sec-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, methacrylic acid Methacrylic acid esters without functional groups such as isobornyl, phenyl methacrylate, benzyl methacrylate; methoxyethyl methacrylate, ethoxyethyl methacrylate, diethylaminoethyl methacrylate, 2-hydroxyethyl methacrylate, 2-aminoethyl methacrylate, Examples thereof include methacrylic acid esters having functional groups such as glycidyl methacrylate and tetrahydrofurfuryl methacrylate.

Among these, methacrylic acid ester having no functional group is preferable from the viewpoint of improving the heat resistance and durability of the obtained polymer, and methyl methacrylate, ethyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, etc. Isobornyl methacrylate and phenyl methacrylate are more preferable, and methyl methacrylate is further preferable because the phase separation between the polymer blocks (A1) and (A2) and the polymer block (B) becomes clearer and the cohesive force becomes higher. .. The polymer blocks (A1) and (A2) may be composed of one kind of these methacrylic acid esters, or may be composed of two or more kinds. Further, the acrylic triblock copolymer (I) has two polymer blocks (A1) and (A2) as polymer blocks composed of methacrylic acid ester units, and these polymer blocks (A1) and The methacrylic acid esters constituting (A2) may be the same or different. The proportion of the methacrylic acid ester unit contained in the polymer blocks (A1) and (A2) is preferably 60% by mass or more in each of the polymer blocks (A1) and (A2), and is 80%. By mass% or more is more preferable, 90% by mass or more is further preferable, and 95% by mass or more is further preferable. Further, the ratio of the methacrylic acid ester units of the polymer blocks (A1) and (A2) may be 100% by mass.

The stereoregularity of the methacrylic acid ester units contained in the polymer blocks (A1) and (A2) composed of the methacrylic acid ester units may be the same or different from each other.

In the acrylic triblock copolymer (I), the total content of the polymer blocks (A1) and (A2) is 35% by mass or less, preferably 30% by mass or less, and preferably 25% by mass or less. More preferably, it is more preferably 20% by mass or less. The total content of the polymer blocks (A1) and (A2) is preferably 4% by mass or more, and more preferably 8% by mass or more. When the total content of the polymer blocks (A1) and (A2) is within the above range, excellent cohesive force is obtained when the acrylic triblock copolymer (I) is used in the adhesive composition. It develops and improves tack and adhesive strength. Further, the adhesive composition tends to have more excellent heat-resistant adhesiveness and holding power. Further, the contents of the polymer blocks (A1) and (A2) contained in the acrylic triblock copolymer (I) may be the same or different.

The glass transition temperature (Tg) of each of the polymer blocks (A1) and (A2) is preferably 60 to 140 ° C, more preferably 70 to 130 ° C, and further preferably 80 to 130 ° C. preferable. When the glass transition temperature is in this range, the polymer blocks (A1) and (A2) act as physical pseudo-crosslink points at the normal operating temperature of the adhesive, and cohesive force is exhibited. When used in an adhesive composition, it has excellent adhesive properties, durability, heat resistance, and the like. The glass transition temperature in the present specification is the extrapolation start temperature of the curve obtained by DSC measurement.

The Tg of each of the polymer blocks (A1) and (A2) may be the same or different. Even when the Tg of each of the polymer blocks (A1) and (A2) is different, it is preferable that the Tg of both polymer blocks is in the above range.

(Polymer block (B))
The acrylic triblock copolymer (I) has one polymer block (B) made of an acrylic acid ester unit.

Examples of the acrylic acid ester serving as a constituent unit of the polymer block (B) include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, and acrylate. sec-butyl, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, isobornyl acrylate, acrylic acid Acrylic acid esters without functional groups such as lauryl, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate; methoxyethyl acrylate, ethoxyethyl acrylate, 2-hydroxyethyl acrylate, 2 acrylate -Acrylic acid esters having a functional group such as aminoethyl, glycidyl acrylate, tetrahydrofurfuryl acrylate, diethylaminoethyl acrylate, and phenoxyethyl acrylate can be mentioned.

Above all, from the viewpoint of transparency and flexibility when prepared as an adhesive composition, it is represented by the general formula CH ₂ = CH-COOR ¹ (in the formula, R ¹ represents an organic group having 1 to 10 carbon atoms). Acrylic acid ester is more preferable, and acrylic acid is used because the phase separation between the polymer blocks (A1) and (A2) and the polymer block (B) becomes clear and the adhesive composition exhibits high cohesiveness. Methyl, ethyl acrylate, isopropyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, tert-butyl acrylate, amyl acrylate, isoamyl acrylate, n- acrylate Acrylic acid esters without functional groups such as hexyl, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, isobornyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate Even more preferable. Further, methyl acrylate and n-butyl acrylate are obtained from the viewpoint that the adhesive composition has appropriate adhesiveness at room temperature and exhibits stable adhesive force under a wide temperature range and a wide peeling speed condition. , 2-Ethylhexyl acrylate, n-octyl acrylate and isooctyl acrylate are more preferred, and n-butyl acrylate is particularly preferred.

The polymer block (B) may be composed of one kind of these acrylic acid esters, or may be composed of two or more kinds. The proportion of the acrylic acid ester unit contained in the polymer block (B) is preferably 60% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, still more preferably 95% by mass or more. Moreover, the ratio of the acrylic acid ester unit of the polymer block (B) may be 100% by mass.

In the acrylic triblock copolymer (I), the content of the polymer block (B) is usually 65% by mass or more, preferably 70% by mass or more, and more preferably 75% by mass or more. It is preferably 80% by mass or more, and more preferably 80% by mass or more. The content of the polymer block (B) is preferably 96% by mass or less, and more preferably 92% by mass or less. When the content of the polymer block (B) is within the above range, when the acrylic triblock copolymer (I) is used in the adhesive composition, excellent cohesive force is exhibited, and the tackiness is increased. Adhesive strength is further improved.

The glass transition temperature (Tg) of the polymer block (B) is preferably −100 to 30 ° C., more preferably −80 to 10 ° C., and even more preferably −70 to 0 ° C. When the glass transition temperature is in this range, it can have excellent tack and adhesive strength when used in an adhesive composition.

The polymer blocks (A1) and (A2) and the polymer block (B) may contain each other's monomer components as long as the effects of the present invention are not impaired. For example, it may have a tapered structure at the boundary between the polymer block (A1) or (A2) and the polymer block (B). Further, the polymer block (A1) or (A2) and the polymer block (B) may not contain each other's monomer components.

Further, the polymer blocks (A1) and (A2) and the polymer block (B) may contain other monomers, if necessary. Examples of such other monomers include vinyl-based monomers having a carboxyl group such as (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, and fumaric acid; (meth) acrylamide, (meth) acrylonitrile, and the like. Vinyl-based monomers having functional groups such as vinyl acetate, vinyl chloride, vinylidene chloride; aromatic vinyl-based monomers such as styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene; butadiene, isoprene, etc. Conjugate diene-based monomers; olefin-based monomers such as ethylene, propylene, isobutene, and octene; lactone-based monomers such as ε-caprolactone and valerolactone. When each polymer block contains these other monomers, the content thereof is preferably 20% by mass or less, more preferably 10% by mass, based on the total mass of the monomers constituting each polymer block. % Or less, more preferably 5% by mass or less.

The acrylic triblock copolymer (I) has a (A1)-(B)-(A2) block structure in which the polymer block (A1), the polymer block (B), and the polymer block (A2) are bonded in this order. Has. When the acrylic triblock copolymer (I) has this structure, an adhesive composition having excellent adhesive strength, holding power, and cohesive strength can be obtained.

The weight average molecular weight (Mw) of the acrylic triblock copolymer (I) is 50,000 to 250,000. From the viewpoint of cohesive force and handleability at the time of manufacture, it is preferably 70,000 to 250,000, more preferably 100,000 to 250,000, and 130,000 to 250,000. Is even more preferable. If the Mw of the acrylic triblock copolymer (I) is less than 50,000, the cohesive force may be inferior. Further, if Mw exceeds 250,000, the handleability at the time of manufacturing may be inferior.

The molecular weight distribution (Mw / Mn) of the acrylic triblock copolymer (I) is preferably 1.0 to 1.5, and more preferably 1.0 to 1.4. The weight average molecular weight (Mw) and the number average molecular weight (Mn) in the present specification are the standard polystyrene-equivalent weight average molecular weight and the number average molecular weight obtained by gel permeation chromatography (GPC) measurement.

The method for producing the acrylic triblock copolymer (I) used in the present invention is not particularly limited as long as a polymer satisfying the conditions of the present invention regarding the chemical structure can be obtained, and conforms to a known method. The method can be adopted. Generally, as a method of obtaining a block copolymer having a narrow molecular weight distribution, a method of living-polymerizing a monomer as a constituent unit is adopted. Examples of such a living polymerization method include a method of living polymerization using an organic rare earth metal complex as a polymerization initiator (see JP-A-06-93060), and an alkali metal or alkaline soil using an organic alkali metal compound as a polymerization initiator. A method of living anion polymerization in the presence of a mineral acid such as a salt of a similar metal (see Japanese Patent Application Laid-Open No. 05-507737), living anion polymerization using an organic alkali metal compound as a polymerization initiator in the presence of an organic aluminum compound. (Refer to JP-A-11-335432), Atom Transfer Radical Polymerization Method (ATRP) (Macromolecular Chemistry and Physics, 2000, Vol. 201, p. 1108 to 1114) and the like.

Among the above production methods, the method of living anionic polymerization using an organoalkali metal compound as a polymerization initiator in the presence of an organoaluminum compound results in high transparency of the obtained block copolymer, a small amount of residual monomers, and an odor. It is preferable because it can suppress the generation of air bubbles after bonding when used as an adhesive composition. Furthermore, the molecular structure of the methacrylic ester polymer block becomes highly syndiotactic, which has the effect of increasing the heat resistance of the adhesive composition, and can be industrially polymerized in the living room under relatively mild temperature conditions. It is also preferable in that the environmental load (mainly the power required for the refrigerator for controlling the polymerization temperature) is small in the case of production.

Examples of the organoaluminum compound include the following general formula (1).
AlR ² R ³ R ⁴ (1)
(In the formula (1), R ² , R ³ and R ⁴ each have an alkyl group which may independently have a substituent, a cycloalkyl group which may have a substituent, and a substituent. Table represents an aryl group which may have a substituent, an aralkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, or an N, N-disubstituted amino group. Or, R ² is one of the groups described above, and R ³ and R ⁴ together form an allylene oxy group which may have a substituent.) Examples include aluminum compounds.

The organoaluminum compound represented by the general formula (1) is isobutylbis (2,6-di-tert-butyl-4-methylphenoxy) from the viewpoint of high living property of polymerization and ease of handling. Aluminum, isobutylbis (2,6-di-tert-butylphenoxy) aluminum, isobutyl [2,2'-methylenebis (4-methyl-6-tert-butylphenoxy)] aluminum and the like are preferable.

Examples of the organic alkali metal compound include alkyllithium and alkyldilithium such as n-butyllithium, sec-butyllithium, isobutyllithium, tert-butyllithium, n-pentyllithium and tetramethylenedilithium; phenyllithium, p. -Aryllithium and aryldilithium such as trilllithium and lithium naphthalene; aralkyllithium and aralkyldilithium such as dilithium produced by the reaction of benzyllithium, diphenylmethyllithium, diisopropenylbenzene and butyllithium; lithium such as lithiumdimethylamide Amid; Examples thereof include lithium alkoxides such as methoxylithium and ethoxylithium. These may be used alone or in combination of two or more. Of these, alkyllithium is preferable because of its high polymerization initiation efficiency, and tert-butyllithium and sec-butyllithium are more preferable, and sec-butyllithium is even more preferable.

The living anionic polymerization is usually carried out in the presence of a solvent that is inert to the polymerization reaction. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as chloroform, methylene chloride and carbon tetrachloride; ethers such as tetrahydrofuran and diethyl ether, and toluene is preferably used. Be done.

The block copolymer is, for example, a step of forming a desired polymer block (polymer block (A1), polymer block (B), etc.) at a desired living polymer terminal obtained by polymerizing a monomer. It can be produced by stopping the polymerization reaction after repeating the process a desired number of times. Specifically, for example, in the presence of an organic aluminum compound, the first step and the second polymer block for polymerizing the monomer forming the first polymer block with a polymerization initiator composed of an organic alkali metal compound are used. The active terminal of the obtained polymer is subjected to a multi-step polymerization step including a second step of polymerizing the polymer to be formed and a third step of polymerizing the monomer forming the third polymer block. The acrylic triblock copolymer (I) can be produced by reacting with alcohol or the like to stop the polymerization reaction. According to the above method, a triblock copolymer composed of a polymer block (A1) -polymer block (B) -polymer block (A2) can be produced.

The polymerization temperature is preferably 0 to 100 ° C. when forming the polymer blocks (A1) and (A2), and −50 to 50 ° C. when forming the polymer block (B). When the polymerization temperature is lower than the above range, the progress of the reaction is slowed down, and it takes a long time to complete the reaction. On the other hand, when the polymerization temperature is higher than the above range, the deactivation of the living polymer terminal increases, the molecular weight distribution becomes wide, and a desired block copolymer cannot be obtained. Further, the polymer blocks (A1) and (A2) and the polymer block (B) can be polymerized in the range of 1 second to 20 hours, respectively.

(Adhesive-imparting resin)
The adhesive composition of the present invention contains a tackifier resin. By including the tackifier resin in the adhesive composition of the present invention, the adhesiveness, tackiness and compatibility are improved. In addition, it is a preferable aspect that the pressure-sensitive adhesive composition of the present invention does not contain a plasticizer described later.

As the tackifier resin that can be blended in the pressure-sensitive adhesive composition of the present invention, any of the tackifier resins conventionally used in pressure-sensitive adhesives can be used and is not particularly limited. For example, a rosin-based resin (rosin, Rosin derivatives, hydrogenated rosin derivatives, etc.), terpene resins, terpenphenol resins, (hydrogenated) petroleum resins, styrene resins, xylene resins, hydride aromatic copolymers, phenolic resins, kumaron-indene resins And so on.

In the present invention, the rosin-based resin is an amber-colored, amorphous natural resin obtained from pine, and its main component is a mixture of abietic acid and its isomers. Further, the rosin-based resin also includes those modified by esterification, polymerization, hydrogenation, etc. by utilizing the reactivity of this abietic acid or its isomer. For example, unmodified rosins (eg, tall rosins, gum rosins, and wood rosins), polymerized rosins, disproportionated rosins, hydrogenated rosins, maleic acid modified rosins, fumaric acid modified rosins, and esters thereof (eg, glycerin esters, penta Examples thereof include erythritol ester, methyl ester, ethyl ester, butyl ester, ethylene glycol ester, etc.) and those modified by hydrogenation (hereinafter, also referred to as hydrogenation), etc., particularly from the viewpoint of heat resistance and color resistance. Hydrogenated rosin ester is preferably used.

In the present invention, the terpene-based resin is an oligomer obtained by polymerizing a raw material containing a terpene-based monomer. Further, the terpene-based resin also includes an oligomer obtained by modifying the oligomer obtained in this manner by hydrogenation or the like. Terpenes generally mean polymers of isoprene (C ₅ H ₈ ) and are classified into _{monoterpenes (C 10} H ₁₆ ), sesquiterpenes (C ₁₅ H ₂₄ ), diterpenes (C ₂₀ H _{32), etc.} To. The terpene-based monomer is a monomer having these as a basic skeleton. -Terpinene, terpinene, 1,8-cineole, 1,4-cineole, α-terpineneol, β-terpineneol, γ-terpineneol, sabinene, paramentadiens, curenes and the like can be mentioned. Further, the raw material containing terpene monomer, terpene monomer and other copolymerizable monomers, for example coumarone based monomers such as benzofuran (C ₈ H ₆ O); styrene, alpha- Vinyl aromatic compounds such as methylstyrene, vinyltoluene, divinyltoluene, 2-phenyl-2-butene; phenol, cresol, xylenol, propylphenol, norylphenol, hydroquinone, resorcin, methoxyphenol, bromophenol, bisphenol A, bisphenol F And the like may be contained. Examples of the oligomer obtained by polymerizing a raw material containing another monomer copolymerizable with the terpene-based monomer include a terpene phenol-based resin and the like. In addition, the oligomer obtained in this way modified by hydrogenation or the like is also included in the terpene resin.

In the present invention, the (hydrogenated) petroleum-based resin is composed of a C ₅ fraction, a C ₉ fraction, _{a purified component of the C 5} fraction, a purified component of the C ₉ fraction, or a mixture of these fractions or purified components. It is an oligomer obtained by polymerizing a raw material. Further, the oligomer obtained in this manner modified by hydrogenation or the like is also included in the above (hydrogenated) petroleum-based resin. Note that the C ₅ fraction, typically, cyclopentadiene, dicyclopentadiene, isoprene, 1,3-pentadiene, 2-methyl-1-butene, 2-methyl-2-butene, 1-pentene, 2-pentene and Cyclopentene and the like are included, and the C ₉ distillate usually contains styrene, allylbenzene, α-methylstyrene, vinyltoluene, β-methylstyrene, indene and the like. In addition, the C ₉ fraction may contain a small amount of the C ₈ fraction and the C _{10 fraction.}

The (hydrogenated) petroleum resin, C ₅ fraction or C ₅ resins the purified components were the raw material, C ₉ fraction or C ₉ resins the purified components to the raw material, C ₅ fraction or purified components thereof the a C ₉ fraction or mixture with its purified components were the raw material is roughly classified into C ₅ -C ₉ copolymer resin. Among these, hydrogenated petroleum-based resins are preferably used from the viewpoint of heat resistance and color resistance.

In the present invention, the aromatic hydrocarbon-based resins such as styrene-based resin, xylene-based resin, hydrogenated aromatic copolymer, and phenol-based resin are, for example, styrene, α-methylstyrene, vinyltoluene, β-methylstyrene, and divinyltoluene. , 2-Phenyl-2-butene, methoxystyrene, t-butylstyrene, chlorostyrene, inden, methylinden, phenol, cresol, xylenol, propylphenol, norylphenol, hydroquinone, resorcin, methoxyphenol, bromophenol, bisphenol A, It is an oligomer obtained by polymerizing a raw material composed of bisphenol F or a mixture thereof. Further, the oligomer obtained in this manner modified by hydrogenation or the like is also included. In addition, Kumaron-inden resin and the like can also be mentioned. Among these, a styrene resin is preferably used from the viewpoint of compatibility, heat resistance, and color resistance.

These tackifier resins may be contained alone or in combination of two or more. When two or more of these tackifier resins are contained, it is desirable because the adhesive strength and tack balance are excellent. The softening point of the tackifier resin is preferably 50 to 160 ° C. from the viewpoint of exhibiting high adhesive strength.

The content of the tackifier resin is 1 to 190 parts by mass with respect to 100 parts by mass of the acrylic triblock copolymer (I). When the tackifier resin is a rosin-based resin, a terpenphenol-based resin, a styrene-based resin, a xylene-based resin, a hydrogenated aromatic copolymer, a phenol-based resin, a kumaron-inden-based resin, etc., the content of the tackifier resin is within the above range. If there is, the balance of adhesive strength, tackiness and cohesive strength of the adhesive composition is excellent. From the viewpoint of achieving both higher adhesive force, tackiness and cohesive force, the content of the tackifier resin is preferably 10 to 180 parts by mass with respect to 100 parts by mass of the acrylic triblock copolymer (I). More preferably, it is 15 to 170 parts by mass.

On the other hand, when the tackifier resin is a terpene resin composed of only (hydrogenated) petroleum resin and terpene monomer, the content is increased from the viewpoint of compatibility with the acrylic triblock copolymer. It tends to be difficult. From the viewpoint of adhesive strength, tack and cohesive strength, and compatibility, the content of the tackifier resin is preferably 2 to 40 parts by mass with respect to 100 parts by mass of the acrylic triblock copolymer (I). It is more preferably 2 to 20 parts by mass.

(Plasticizer)
The adhesive composition of the present invention may contain a plasticizer. By containing a plasticizer in the adhesive composition of the present invention, an adhesive composition having an excellent balance between adhesive strength and tack can be obtained, and more generally, the adhesive composition as a whole can be obtained. Cost can be reduced.

Examples of such plasticizers include phthalates such as dibutylphthalate, din-octylphthalate, bis (2-ethylhexyl) phthalate, bis (2-ethylhexyl) terephthalate, din-decylphthalate and diisodecylphthalate; Adipanoic acid esters such as bis (2-ethylhexyl) adipate, diisodecyl adipate, din-octyl adipate; sebacic acid esters such as bis (2-ethylhexyl) sebacate, din-butyl sebacate; bis (2-ethylhexyl) azelate, etc. Azelaic acid esters; citrate esters such as tributyl acetyl citrate; paraffins such as chlorinated paraffins; glycols such as polypropylene glycol; epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil; trioctyl Phthalate esters such as phosphate and triphenyl phosphate; subphosphate esters such as triphenyl phosphite; esters of adipic acid and 1,3-butylene glycol, esters of benzoic acid and dipropylene glycol, etc. Kind: Low molecular weight polymers such as low molecular weight polybutene, low molecular weight polyisobutylene, low molecular weight polyisoprene; acrylic oligomers such as n-butyl polyacrylate and 2-ethylhexyl polyacrylate; Diana process oil PW series (Idemitsu Kosan Co., Ltd.) , SUNPURE LW70 and P series (manufactured by Nippon Sun Oil Co., Ltd.) and other paraffin oils; SUNPURE N90 and NX90, SUNTHENE series (manufactured by Japan Sun Oil Co., Ltd.) and other naphthenic oils; Aroma-based oils such as (manufactured by company) and Vivatec500 (manufactured by H & R) can be mentioned, and these are used alone or in combination of two or more.

The content of the plasticizer is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, and 60 parts by mass or less with respect to 100 parts by mass of the acrylic triblock copolymer (I). Is even more preferable. When the content of the plasticizer is in the above range, a viscous adhesive composition having excellent transparency and bleed resistance can be obtained. In addition, in order to obtain the effect of containing the plasticizer in the adhesive composition, it is desirable that it is usually contained in an amount of 5 parts by mass or more with respect to 100 parts by mass of the acrylic triblock copolymer (I).

The adhesive composition of the present invention contains other polymers; softeners, heat stabilizers, light stabilizers, antistatic agents, flame retardants, foaming agents, colorants, as long as the effects of the present invention are not impaired. Additives such as a dye, a refractive index adjuster, a filler, a curing agent, and an antistatic agent may be contained. These other polymers and additives may be contained alone or in combination of two or more.

Other polymers include, for example, acrylic resins such as polymethyl methacrylate and (meth) acrylic acid ester copolymers; polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polybutene-1, poly-4-methyl. Olefin-based resins such as Penten-1, polynorbornene; Ethylene-based ionomers; Polystyrene, styrene-maleic anhydride copolymers, high-impact polystyrene, AS resin, ABS resin, AES resin, AAS resin, ACS resin, MBS resin, etc. Polystyrene resin; styrene-methyl methacrylate copolymer; polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polylactic acid; polyamide such as nylon 6, nylon 66, polyamide elastomer; polycarbonate; polyvinyl chloride; polyvinylidene chloride; polyvinyl Alcohol; ethylene-vinyl alcohol copolymer; polyacetal; vinylidene fluoride; polyurethane; modified polyphenylene ether; polyphenylene sulfide; silicone rubber modified resin; acrylic rubber; silicone rubber; styrene-based thermoplastic elastomer such as SEPS, SEBS, SIS, etc. ; Examples include olefin-based rubbers such as IR, EPR, and EPDM. Among these, from the viewpoint of compatibility with the acrylic triblock copolymer (I) contained in the adhesive composition, acrylic resin, ethylene-vinyl acetate copolymer, AS resin, polylactic acid, Polyvinylidene fluoride and styrene-based thermoplastic elastomers are preferable, and (meth) acrylic acid ester copolymers are more preferable.

Examples of the filler include inorganic fibers such as glass fiber and carbon fiber, and organic fibers; inorganic fillers such as calcium carbonate, talc, titanium oxide, silica, clay, barium sulfate and magnesium carbonate; carbon black and the like. .. When inorganic fibers and organic fibers are contained, durability is imparted to the obtained adhesive composition. When the inorganic filler is contained, heat resistance and weather resistance are imparted to the obtained adhesive composition.

When the adhesive composition of the present invention contains a curing agent, it can be suitably used as a curing adhesive. Examples of the curing agent include photocuring agents such as UV curing agents, heat curing agents, and the like, and examples thereof include benzoins, benzoin ethers, benzophenones, anthraquinones, benzyls, acetophenones, and diacetyls. .. Specifically, benzoin, α-methylol benzoin, α-t-butyl benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n-propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α-methylol benzoin methyl ether, α −methoxybenzoin methyl ether, benzoinphenyl ether, benzophenone, 9,10-anthraquinone, 2-ethyl-9,10-anthraquinone, benzyl, 2,2-dimethoxy-1,2-diphenylethane-1-one (2,2) −Dimethoxy-2-phenylacetophenone), diacetyl and the like. The curing agent may be contained alone or in combination of two or more.

From the viewpoint of enhancing the effect of the above-mentioned curing agent, for example, acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-halogenated acrylic acid, crotonic acid, cinnamic acid, sorbic acid, maleic acid, itaconic acid, and acrylic acid ester. , Methacrylic acid ester, crotonic acid ester, maleic acid ester and other esters; acrylamide; methacrylic amide; N-methylol acrylamide, N-hydroxyethyl acrylamide, N, N- (dihydroxyethyl) acrylamide and other acrylamide derivatives; N-methylol methacrylic Methacrylic amide derivatives such as amide, N-hydroxyethyl methacrylic amide, N, N- (dihydroxyethyl) methacrylic amide; vinyl ester; vinyl ether; mono-N-vinyl derivative; monomer such as styrene derivative; Oligomers and the like contained as constituents may be further contained in the adhesive composition of the present invention. From the viewpoint of increasing durability, esters such as acrylic acid ester, methacrylic acid ester, crotonic acid ester, and maleic acid ester; vinyl ether; styrene derivative; and an oligomer containing the monomer as a constituent are preferable. Further, in addition to these monomers, a cross-linking agent composed of a bifunctional or higher functional monomer or oligomer may be further contained.

When the adhesive composition of the present invention contains an anti-adhesive agent, improvement in handleability can be expected. Examples of the anti-sticking agent include fatty acids such as stearic acid and palmitic acid; fatty acid metal salts such as calcium stearate, zinc stearate, magnesium stearate, potassium palmitate, and sodium palmitate; polyethylene wax, polypropylene wax, and montanic acid. Waxes such as waxes; low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene; acrylic resin powders; polyorganosiloxanes such as dimethylpolysiloxane; octadecylamine, alkyl phosphate, fatty acid esters, ethylene bisstearylamide, etc. Examples thereof include amide-based resin powder, fluororesin powder such as ethylene tetrafluoride resin, molybdenum disulfide powder, silicone resin powder, silicone rubber powder, and silica.

The method for producing the adhesive composition of the present invention is not particularly limited, and for example, each component is usually mixed or kneaded using a known mixing or kneading device such as a kneader ruder, an extruder, a mixing roll, or a Banbury mixer. It can be manufactured by mixing at a temperature in the range of ~ 250 ° C. Further, it may be produced by dissolving each component in an organic solvent, mixing the components, and then distilling off the organic solvent. The obtained adhesive composition can be used by being melted by heating, or may be dissolved in a solvent and used as a solution type adhesive. Examples of the solvent include toluene, ethyl acetate, ethylbenzene, methylene chloride, chloroform, tetrahydrofuran, methyl ethyl ketone, dimethyl sulfoxide, toluene-ethanol mixed solvent and the like. Of these, toluene, ethylbenzene, ethyl acetate and methyl ethyl ketone are preferable.

When the adhesive composition of the present invention is used by heating and melting, it is preferable that the melt viscosity is low from the viewpoint of processability and handleability. On the other hand, from the viewpoint of achieving both the adhesive properties of the pressure-sensitive adhesive composition and high holding power (creep resistance), it is preferable that the melt viscosity is high.
The adhesive composition of the present invention is adhesive in the form of an adhesive layer made of the adhesive composition, a laminate containing the adhesive layer (for example, a laminated film or a laminated sheet), or the like. Suitable for adhesive products.

In order to form the adhesive layer, when the adhesive composition of the present invention is used by heating and melting, for example, a hot melt coating method, a T-die method, an inflation method, a calendar molding method, a lamination method and the like are used. It can be used to form a sheet or film. When the melt viscosity of the pressure-sensitive adhesive composition of the present invention is high, for example, when the melt viscosity at 180 ° C. exceeds 20,000 mPa · s, it is heated and melted from a T die in order to heat and melt at a higher temperature. A hot melt coating method in which an object is applied onto the support in a non-contact manner is preferable from the viewpoints of controlling the thickness of the adhesive layer, homogeneity, and the heat resistance required for the support. When the adhesive composition of the present invention is used by dissolving it in a solvent, for example, a heat-resistant material such as polyethylene terephthalate or a flat plate or roll such as a steel belt is used as a support, and a bar coater or a roll is used on the flat plate or roll. A method of applying a solution in which a composition containing an acrylic triblock copolymer (I) and a tackifier resin is dissolved in a solvent using a roll coater, a die coater, a comma coater, or the like, and removing the solvent by drying. A viscous adhesive layer can be formed using (solution casting method).

The method for removing the solvent by drying is not particularly limited, and a conventionally known method can be used, but it is preferable to perform drying in a plurality of steps. When drying is performed in multiple stages, the first stage is dried at a relatively low temperature in order to suppress foaming due to the rapid volatilization of the solvent, and the second and subsequent stages are sufficiently dried. A method of drying at a high temperature is more preferable in order to remove the solvent.

The concentration of the composition containing the acrylic triblock copolymer (I) and the tackifier resin in the solution is appropriately determined in consideration of the solubility of the composition in the solvent, the viscosity of the obtained solution, and the like. The preferred lower limit is 5% by mass, and the preferred upper limit is 70% by mass.

The above-mentioned laminate is obtained by laminating various base materials such as paper, cellophane, plastic material, cloth, wood, and metal with the adhesive layer made of the adhesive composition of the present invention. A base material layer made of a transparent material is suitable because the adhesive composition of the present invention is excellent in transparency and weather resistance, and thus a transparent laminate can be obtained. Examples of the base material layer made of a transparent material include polyethylene terephthalate, triacetyl cellulose, polyvinyl alcohol, cycloolefin resin, styrene-methyl methacrylate copolymer, polypropylene, polyethylene, polyvinyl chloride, and ethylene-vinyl acetate copolymer. , Polypolymers such as polycarbonate, polymethylmethacrylate, polyethylene or polypropylene and copolymers of various monomers, mixtures of two or more of these polymers, and a base material layer made of glass or the like. It is not limited.

The structure of the laminate includes, for example, a two-layer structure consisting of an adhesive layer made of the adhesive composition of the present invention and a base material layer, and two layers of the base material layer and the adhesive adhesive composition of the present invention. A three-layer structure consisting of an adhesive layer (base material layer / adhesive layer / base material layer), and two different adhesive layers composed of the base material layer and the adhesive composition of the present invention (base material layer / adhesive layer / base material layer). A) and a four-layer structure of the adhesive layer (b) and the base material layer (base material layer / adhesive layer (a) / adhesive layer (b) / base material layer), the base material layer and the invention A four-layer structure (base material layer / adhesive layer (a)) consisting of an adhesive layer (a) made of the adhesive composition of the present invention, an adhesive layer (c) made of another material, and a base material layer. ) / Adhesive layer (c) / Base material layer), 5 layers of 3 layers of base material layer and 2 layers of adhesive layer composed of the adhesive composition of the present invention (base material layer / adhesive) (Assembly layer / base material layer / adhesive layer / base material layer) and the like, but are not limited thereto.

The thickness ratio of the laminate is not particularly limited, but is in the range of base material layer / adhesive layer = 1/1000 to 1000/1 from the viewpoint of the adhesiveness, durability, and handleability of the obtained adhesive product. It is preferably in the range of 1/200 to 200/1, and more preferably in the range of 1/200 to 200/1.

When producing the above-mentioned laminate, the adhesive layer and the base material layer may be formed and then bonded together by a lamination method or the like, or the adhesive layer may be formed directly on the base material layer. Good. Further, the layer structure may be formed at once by co-extruding the adhesive layer and the base material layer to produce a laminate as, for example, a co-extruded film or a co-extruded sheet.

In the laminate of the present invention, in order to enhance the adhesion between the base material layer and the adhesive layer, the surface of the base material layer may be subjected to surface treatment such as corona discharge treatment or plasma discharge treatment in advance. Further, an anchor layer may be formed on at least one surface of the adhesive layer and the base material layer by using an adhesive resin or the like.

Examples of the resin used for the anchor layer include ethylene-vinyl acetate copolymers, ionomers, block copolymers (for example, styrene-based triblock copolymers such as SIS and SBS, and diblock copolymers). Examples thereof include ethylene-acrylic acid copolymers and ethylene-methacrylic acid copolymers. The anchor layer may be one layer or two or more layers.

When forming the anchor layer, the method is not particularly limited, and for example, a method of applying a solution containing the above resin to the base material layer to form the anchor layer, a composition containing the above resin or the like as the anchor layer, and the like. Examples thereof include a method of forming an anchor layer on the surface of the base material layer by heating and melting with a T-die or the like.

Further, when forming the anchor layer, the above resin serving as the anchor layer and the adhesive composition of the present invention may be coextruded and the anchor layer and the adhesive layer may be integrally laminated on the surface of the base material layer. , The resin to be the anchor layer and the adhesive composition may be sequentially laminated on the surface of the base material layer, and when the base material layer is a plastic material, the plastic material to be the base material layer and the anchor The resin to be a layer and the adhesive composition may be co-extruded at the same time.

The adhesive adhesive composed of the adhesive adhesive composition of the present invention can be used for various purposes. Further, the adhesive layer made of the adhesive composition can be used alone as an adhesive sheet, and a laminate containing the adhesive layer can also be applied to various uses. For example, for protection such as surface protection, for masking, for bundling, for packaging, for office work, for labels, for decoration / display, for joining, for dicing tape, for sealing, for anticorrosion / waterproof, for medical / sanitary, glass Adhesive adhesive for shatterproofing, electrical insulation, holding and fixing electronic devices, semiconductor manufacturing, optical display film, adhesive optical film, electromagnetic wave shield, or encapsulant for electrical and electronic parts Examples include tapes, films or sheets. Specific examples will be given below.

Adhesive adhesives, adhesive tapes, films, etc. for surface protection can be used for various materials such as metals, plastics, rubber, and wood. , Can be used to protect the surface of optical members. Examples of the automobile member include a painted outer panel, a wheel, a mirror, a window, a light, a light cover, and the like. The optical members include various image display devices such as liquid crystal displays, organic EL displays, plasma displays, and field emission displays; polarizing films, polarizing plates, retardation plates, light guide plates, diffusers, and optical disk constituent films such as DVDs; electrons. -Precision fine coated face plates for optical applications can be mentioned.

Applications such as adhesives for masking, tapes and films include masking during manufacturing of printed boards and flexible printed boards; masking during plating and soldering with electronic devices; manufacturing of vehicles such as automobiles, vehicles and construction. Examples include painting, printing, and masking when civil work is closed.

Bundling applications include wire harnesses, electric wires, cables, fibers, pipes, coils, windings, steel materials, ducts, plastic bags, foods, vegetables, flowers and the like.
Examples of packaging applications include heavy-duty packaging, export packaging, corrugated cardboard box sealing, and can seals.

Examples of office use include general-purpose office work, sealing, book repair, drafting, memos, and the like.
Labels include prices, product displays, tags, POPs, stickers, stripes, nameplates, decorations, advertisements, and the like.

The above labels include paper, processed paper (paper that has been subjected to aluminum vapor deposition processing, aluminum laminating processing, varnish processing, resin processing, etc.), synthetic paper, and other paper; made of cellophane, plastic material, cloth, wood, and metal. Examples thereof include labels using a film or the like as a base material. Specific examples of the base material include high-quality paper, art paper, cast paper, thermal paper, foil paper; polyethylene terephthalate film, polyvinyl chloride film, OPP film, polylactic acid film, synthetic paper, synthetic paper thermal, and overlay. Examples include films. Above all, the adhesive composition of the present invention is excellent in transparency and weather resistance, and can be suitably used for a label using a base material made of a transparent material. Further, since the adhesive composition of the present invention is less discolored with time, it can be suitably used for a thermal label using thermal paper or synthetic paper thermal as a base material.

Examples of the adherend of the label include plastic products such as plastic bottles and foamed plastic cases; paper and cardboard products such as cardboard boxes; glass products such as glass bottles; metal products; and other inorganic material products such as ceramics. Be done.

The label made of a laminate containing an adhesive layer made of the adhesive composition of the present invention has little adhesion enhancement during storage at a temperature slightly higher than room temperature (for example, 40 ° C), and can be peeled off without adhesive residue after use. it can. Moreover, it can be attached to the adherend even at a low temperature (-40 to + 10 ° C.) and will not peel off even when stored at a low temperature (-40 to + 10 ° C.).

Examples of decorative / display applications include danger display stickers, line tapes, wiring markings, phosphorescent tapes, reflective sheets, and the like.
Adhesive optical film applications include, for example, polarizing films, polarizing plates, retardation films, viewing angle enlargement films, brightness improving films, antireflection films, antiglare films, color filters, light guide plates, diffusion films, prism sheets, electromagnetic wave shielding films. , Near-infrared absorbing film, functional composite optical film, ITO bonding film, impact resistance imparting film, brightness improving film, visibility improving film, etc., forming an adhesive layer on at least part or all of one side or both sides Optical film and the like. Such an adhesive type optical film includes a film in which an adhesive layer made of the adhesive composition of the present invention is formed on a protective film used for surface protection of the optical film. The adhesive optical film is suitably used for various image display devices such as liquid crystal display devices, PDPs, organic EL display devices, electronic papers, game machines, and mobile terminals.

Examples of electrical insulation applications include protective coating or insulation of coils, interlayer insulation of motors and transformers, and the like.
Examples of applications for holding and fixing electronic devices include carrier tape, packaging, fixing of cathode ray tubes, splicing, and rib reinforcement.

Examples of semiconductor manufacturing include protection of silicon wafers.
Examples of the bonding application include various bonding fields, automobiles, trains, electric devices, printing plate fixing, construction, name plate fixing, general household use, rough surface, uneven surface, bonding to curved surfaces and the like.

Examples of sealing applications include sealing for heat insulation, vibration isolation, waterproofing, moisture proofing, soundproofing or dustproofing.
Examples of anticorrosion / waterproof applications include anticorrosion of gas and water pipes, anticorrosion of large diameter pipes, and anticorrosion of civil engineering buildings.

For medical and hygiene applications, analgesic and anti-inflammatory agents (plaster, pap), ischemic heart disease therapeutic agents, female hormone replacement agents, bronchial dilators, cancer pain relievers, quitting aids, adhesive plasters, antipruritic patches, Percutaneous absorbents such as keratin softeners; First aid adhesive plasters (with bactericides), surgical dressing / surgical tapes, adhesive plasters, hemostatic bonds, human excrement treatment equipment tapes (artificial anal fixation tapes), suture tapes, antibacterial tapes , Fixed taping, self-adhesive bandage, oral mucosa sticking tape, sports tape, hair removal tape, etc.; beauty applications such as face pack, eye moisturizing sheet, keratin peeling pack; cooling sheet, thermal cairo, dustproof, Examples include waterproofing and pest catching.
Examples of encapsulants for electronic and electrical parts include liquid crystal monitors and solar cells.

Hereinafter, the present invention will be specifically described with reference to Examples, Comparative Examples and the like, but the present invention is not limited to the following examples. In Production Examples 1 to 6 shown below, the monomers and other compounds were dried and purified by a conventional method, degassed with nitrogen, and used. In addition, the transfer and supply of monomers and other compounds to the reaction system was carried out in a nitrogen atmosphere.

In the following examples, the weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the polymer (polymer forming the block) and the block copolymer are determined by GPC in terms of polystyrene-equivalent molecular weight. It was. The measuring devices and conditions used in GPC are as follows.
[GPC measurement equipment and conditions]
・ Equipment: GPC equipment "HLC-8020" manufactured by Tosoh Corporation
-Separation column: "TSKgel GMHXL", "G4000HXL" and "G5000HXL" manufactured by Tosoh Corporation are connected in series.-Eluent: tetrahydrofuran-Eluent flow rate: 1.0 ml / min-Column temperature: 40 ° C.
-Detection method: Differential refractometer (RI)
Further, in the following example, the content of each polymer block in the block copolymer was ^{determined by 1} H-NMR measurement. ^{1 The} measuring equipment and conditions used in the 1 H-NMR measurement are as follows.

[ ¹ Equipment and conditions for 1 H-NMR measurement]
・ Equipment: Nuclear magnetic resonance equipment "JNM-LA400" manufactured by JEOL Ltd.
・ Deuterated solvent: Deuterated chloroform
In ¹ H-NMR spectrum, signals in the vicinity of 3.6ppm and 4.0ppm, respectively, the ester group of methyl methacrylate unit (-O-CH ₃₎ and acrylic acid ester unit of the ester group (-O-C H ₂ It belongs to −CH ₂ −CH ₂ −CH ₃ ), and the content of each polymer block was determined by the ratio of the integrated values.
The evaluation of the pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer composed of the pressure-sensitive adhesive composition was performed by the following method.

[Compatibility]
The compatibility was evaluated by the appearance 24 hours after the preparation of the adhesive tape having the pressure-sensitive adhesive layer having a thickness of 25 μm prepared by the method described later. If the adhesive tape is colorless and transparent and no white turbidity is seen, it is rated as "A" (good compatibility), and if it is uneven or cloudy, it is rated as "B" (poor compatibility).

[Bleed property]
The appearance of the adhesive tape having the adhesive layer having a thickness of 25 μm produced by the method described later and immediately after 24 hours was observed, and the evaluation was made by oozing out the liquid material from the surface of the adhesive layer of the adhesive tape. "A" if no bleeding of the liquid material from the surface of the adhesive layer is observed immediately after production or 24 hours after production, and "b" if liquid material oozes from the surface of the tape 24 hours after production. And said.

[Adhesive properties]
At 25 ° C., the resistance when the thumb was pressed against the surface of the adhesive layer of the produced adhesive tape and peeled off was sensory evaluated in three stages (1, 2, 3) as a tack feeling, and this was used as an index of the adhesive characteristics. Here, the larger the number, the higher the adhesiveness (tackiness), "3" indicates a good tackiness, and "2" indicates a tackiness, indicating that the adhesive is suitable as an adhesive. On the other hand, "1" was unsuitable as an adhesive without a feeling of tackiness.

[Thermal stability]
Thermal stability was performed by evaluating the color change in appearance of the obtained adhesive tape before and after heat treatment at 180 ° C. for 3 hours. When the color change could not be confirmed in appearance before and after the heat treatment, it was evaluated as "○", and when the color change could be confirmed, it was evaluated as "Δ".

[Melting viscosity]
The pressure-sensitive adhesive composition prepared by melt-kneading using a kneader described later was set in a B-type viscometer, and the melt viscosity when heated to 160 ° C. and 180 ° C. was measured. The spindle is No. 29 was used.

[Holding power (creep)]
Measured according to JIS Z0237. That is, the produced adhesive tape having a thickness of 25 μm was attached to a stainless steel (SUS304) plate (bright annealed product) with a width of 25 mm and a length of 25 mm, and a load of 500 g was suspended at a temperature of 60 ° C. The deviation distance was calculated.

<< Production Example 1 >> [Production of acrylic triblock copolymer (I-1)]
(1) A three-way cock was attached to a 3 L three-necked flask, the inside was replaced with nitrogen, and then 1408 g of toluene and 32.7 g of 1,2-dimethoxyethane were added while stirring at room temperature, followed by isobutylbis (2,). 6-di-t-Butyl-4-methylphenoxy) Add 48.6 g of a toluene solution containing 24.5 mmol of aluminum, and add 2.39 g of a cyclohexane solution of sec-butyllithium containing 4.08 mmol of sec-butyllithium. added.
(2) Subsequently, 32.6 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring at room temperature for 60 minutes.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 410 g of n-butyl acrylate was added dropwise over 2 hours, and after the addition was completed, the mixture was stirred at −30 ° C. for 5 minutes.
(4) Further, 45.3 g of methyl methacrylate was added thereto, and the mixture was stirred overnight at room temperature.
(5) After adding 15 g of methanol to stop the polymerization reaction, the obtained reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Then, the liquid precipitate was collected and dried to obtain 445 g of an acrylic triblock copolymer (I-1). The weight average molecular weight (Mw) of the obtained acrylic triblock copolymer (I-1) was determined by measuring GPC by the above method. In addition, the total content of the polymer block composed of methyl methacrylate units in the acrylic triblock copolymer (I-1) was determined by the above-mentioned ^{1 H-NMR measurement.}

<< Production Example 2 >> [Production of acrylic triblock copolymer (I-2)]
(1) A three-way cock was attached to a 3 L three-necked flask, the inside was replaced with nitrogen, and then 1409 g of toluene and 32.7 g of 1,2-dimethoxyethane were added while stirring at room temperature, followed by isobutylbis (2,). 6-di-t-Butyl-4-methylphenoxy) Add 48.6 g of a toluene solution containing 24.5 mmol of aluminum, and add 1.50 g of a cyclohexane solution of sec-butyllithium containing 2.55 mmol of sec-butyllithium. added.
(2) Subsequently, 22.7 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring at room temperature for 60 minutes.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 434 g of n-butyl acrylate was added dropwise over 2 hours, and after the addition was completed, the mixture was stirred at −30 ° C. for 5 minutes.
(4) Further, 29.4 g of methyl methacrylate was added thereto, and the mixture was stirred overnight at room temperature.
(5) After adding 15 g of methanol to stop the polymerization reaction, the obtained reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Then, the liquid precipitate was collected and dried to obtain 440 g of an acrylic triblock copolymer (I-2). The weight average molecular weight (Mw) of the obtained acrylic triblock copolymer (I-2) was determined by measuring GPC by the above method. In addition, the total content of the polymer block composed of methyl methacrylate units in the acrylic triblock copolymer (I-2) was determined by the above-mentioned ^{1 H-NMR measurement.}

<< Production Example 3 >> [Production of acrylic triblock copolymer (I-3)]
(1) A three-way cock was attached to a 3 L three-necked flask, the inside was replaced with nitrogen, and then 1409 g of toluene and 32.7 g of 1,2-dimethoxyethane were added while stirring at room temperature, followed by isobutylbis (2,). 6-di-t-Butyl-4-methylphenoxy) Add 48.6 g of a toluene solution containing 24.5 mmol of aluminum, and add 1.85 g of a cyclohexane solution of sec-butyllithium containing 3.15 mmol of sec-butyllithium. added.
(2) Subsequently, 32.6 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring at room temperature for 60 minutes.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 410 g of n-butyl acrylate was added dropwise over 2 hours, and after the addition was completed, the mixture was stirred at −30 ° C. for 5 minutes.
(4) Further, 45.3 g of methyl methacrylate was added thereto, and the mixture was stirred overnight at room temperature.
(5) After adding 15 g of methanol to stop the polymerization reaction, the obtained reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Then, the liquid precipitate was collected and dried to obtain 445 g of an acrylic triblock copolymer (I-3). The weight average molecular weight (Mw) of the obtained acrylic triblock copolymer (I-3) was determined by measuring GPC by the above method. In addition, the total content of the polymer block composed of methyl methacrylate units in the acrylic triblock copolymer (I-3) was determined by the above-mentioned ^{1 H-NMR measurement.}

<< Production Example 4 >> [Production of acrylic triblock copolymer (I-4)]
(1) A three-way cock was attached to a 3 L three-necked flask, the inside was replaced with nitrogen, and then 1302 g of toluene and 65.1 g of 1,2-dimethoxyethane were added while stirring at room temperature, followed by isobutylbis (2,). 6-di-t-Butyl-4-methylphenoxy) Add 120.0 g of a toluene solution containing 60.3 mmol of aluminum, and add 4.34 g of a cyclohexane solution of sec-butyllithium containing 7.50 mmol of sec-butyllithium. added.
(2) Subsequently, 53.9 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring at room temperature for 60 minutes.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 360 g of n-butyl acrylate was added dropwise over 2 hours, and after the addition was completed, the mixture was stirred at −30 ° C. for 5 minutes.
(4) Further, 53.9 g of methyl methacrylate was added thereto, and the mixture was stirred overnight at room temperature.
(5) After adding 20 g of methanol to stop the polymerization reaction, the obtained reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Then, the liquid precipitate was collected and dried to obtain 440 g of an acrylic triblock copolymer (I-4). The weight average molecular weight (Mw) of the obtained acrylic triblock copolymer (I-4) was determined by measuring GPC by the above method. In addition, the total content of the polymer block composed of methyl methacrylate units in the acrylic triblock copolymer (I-4) was determined by the above-mentioned ^{1 H-NMR measurement.}

<< Production Example 5 >> [Production of acrylic triblock copolymer (I-5)]
(1) A three-way cock was attached to a 3 L three-necked flask, the inside was replaced with nitrogen, and then 1409 g of toluene and 32.7 g of 1,2-dimethoxyethane were added while stirring at room temperature, followed by isobutylbis (2,). 6-di-t-Butyl-4-methylphenoxy) Add 48.6 g of a toluene solution containing 24.5 mmol of aluminum, and 2.55 g of a cyclohexane solution of sec-butyllithium containing 4.35 mmol of sec-butyllithium. added.
(2) Subsequently, 43.5 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring at room temperature for 60 minutes.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 360 g of n-butyl acrylate was added dropwise over 2 hours, and after the addition was completed, the mixture was stirred at −30 ° C. for 5 minutes.
(4) Further, 61.5 g of methyl methacrylate was added thereto, and the mixture was stirred overnight at room temperature.
(5) After adding 15 g of methanol to stop the polymerization reaction, the obtained reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Then, the liquid precipitate was collected and dried to obtain 450 g of an acrylic triblock copolymer (I-5). The weight average molecular weight (Mw) of the obtained acrylic triblock copolymer (I-5) was determined by measuring GPC by the above method. In addition, the total content of the polymer block composed of methyl methacrylate units in the acrylic triblock copolymer (I-5) was determined by the above-mentioned ^{1 H-NMR measurement.}

<< Production Example 6 >> [Production of acrylic triblock copolymer (I-6)]
(1) A three-way cock was attached to a 3 L three-necked flask, the inside was replaced with nitrogen, and then 1302 g of toluene and 65.1 g of 1,2-dimethoxyethane were added while stirring at room temperature, followed by isobutylbis (2,). 6-di-t-Butyl-4-methylphenoxy) Add 120.0 g of a toluene solution containing 60.3 mmol of aluminum, and add 4.34 g of a cyclohexane solution of sec-butyllithium containing 7.50 mmol of sec-butyllithium. added.
(2) Subsequently, 69.3 g of methyl methacrylate was added thereto. The reaction solution was initially colored yellow, but became colorless after stirring at room temperature for 60 minutes.
(3) Subsequently, the internal temperature of the polymerization solution was cooled to −30 ° C., 315 g of n-butyl acrylate was added dropwise over 2 hours, and after the addition was completed, the mixture was stirred at −30 ° C. for 5 minutes.
(4) Further, 65.9 g of methyl methacrylate was added thereto, and the mixture was stirred overnight at room temperature.
(5) After adding 20 g of methanol to stop the polymerization reaction, the obtained reaction solution was poured into 15 kg of methanol to precipitate a liquid precipitate. Then, the liquid precipitate was collected and dried to obtain 440 g of an acrylic triblock copolymer (I-6). The weight average molecular weight (Mw) of the obtained acrylic triblock copolymer (I-6) was determined by measuring GPC by the above method. In addition, the total content of the polymer block composed of methyl methacrylate units in the acrylic triblock copolymer (I-6) was determined by the above-mentioned ^{1 H-NMR measurement.}

Block structures of the acrylic triblock copolymers (I-1) to (I-6) obtained in Production Examples 1 to 6, weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), PMMA polymer block. Table 1 shows the total content of (polymer block composed of 100% by mass of methyl methacrylate). In Table 1, PMMA means a polymer block composed of 100% by mass of methyl methacrylate, and PnBA means a block composed of 100% by mass of n-butyl acrylate.

Further, in Examples and Comparative Examples, the following were used as the tackifier resin and the plasticizer.
(Adhesive-imparting resin)
・ Product name “Ysertack311” manufactured by Euro Yser, rosin ester ・ Product name “Ysertack316” manufactured by Euro Yser, rosin ester ・ Product name “Pensel D125” manufactured by Arakawa Chemical Industry Co., Ltd., Polymerized rosin ester ・ Product name “Pensel D160” Arakawa Chemical Made by Kogyo Co., Ltd., Polymerized rosin ester, trade name "KE311" Arakawa Chemical Industry Co., Ltd., Hydrosin rosin ester, trade name "FORAL 85E" made by Eastman, Hydrosin rosin ester, trade name "FORAL AX-E" made by Eastman , Rosinic acid, product name "YS polyster T160" manufactured by Yasuhara Chemical Co., Ltd., terpenphenol resin, product name "YS resin SX100" manufactured by Yasuhara Chemical Co., Ltd., aromatic hydrocarbon resin, product name "Kristalex F100" manufactured by Eastman, fragrance Group hydrocarbon resin, product name "Arkon P100" manufactured by Arakawa Chemical Industry Co., Ltd., hydrogenated petroleum resin, product name "Arkon M100" manufactured by Arakawa Chemical Industry Co., Ltd., hydrogenated petroleum resin (plasticizer)
・ Product name “DOP” manufactured by Shin Nihon Rika Co., Ltd., bis (2-ethylhexyl) phthalate ・ Product name “DOTP” manufactured by Eastman, bis (2-ethylhexyl) terephthalate ・ Product name “ATBC” manufactured by Asahi Kasei Finechem Co., Ltd. Tributyl acid, trade name "K-FLEX DP" manufactured by Kalama chemical, esterified product of benzoic acid and dipropylene glycol, trade name "Micryl 105" manufactured by Polychem, poly n-butyl acrylate oligomer, trade name "ARUFON UP1171" Toa Synthetic Co., Ltd. Company-made acrylate oligomer

[Example 1]
The acrylic triblock copolymer (I-1) obtained in Production Example 1 and the tackifier resin KE311 are added to toluene at the mass ratio shown in Table 2A below so that the total of these is 40% by mass. It was dissolved to prepare a toluene solution containing 40% by mass of the pressure-sensitive adhesive composition. The obtained toluene solution was coated on a polyethylene terephthalate film (Toyobo ester film E5000, thickness 50 μm) with a coater so that the thickness of the adhesive layer after drying was 25 μm, and then the film was coated at 100 ° C. for 3 minutes. The heat treatment was performed to prepare an adhesive tape in which a dry adhesive layer was formed on a polyethylene terephthalate film. The tackiness of the obtained adhesive tape was good, and it was "3". The appearance 24 hours after the preparation of the adhesive tape was transparent, and the compatibility was good "A". Further, no bleeding of the liquid substance was observed from the surface of the adhesive layer immediately after the production of the adhesive tape and 24 hours after the production, and the bleeding property was "a". Moreover, when the color change of the obtained adhesive tape before and after the heat treatment at 180 ° C. for 3 hours was evaluated, the color change could not be confirmed in appearance and the thermal stability was "◯". The evaluation results are shown in Table 2A.

[Examples 2-35]
Toluene solution containing 40% by mass of the pressure-sensitive adhesive composition as in Example 1 except that the composition of the pressure-sensitive adhesive composition is changed to the composition (A-2 to A-35) shown in Tables 2A to C, respectively. And an adhesive tape having an adhesive layer having a thickness of 25 μm formed on a polyethylene terephthalate film were produced, and the obtained adhesive tape was evaluated. The evaluation results are shown in Table 2A, Table 2B, and Table 2C.

[Comparative Example 1]
Similar to Example 1, the preparation of a toluene solution containing 40% by mass of the pressure-sensitive adhesive composition and the thickness were increased, except that the composition of the pressure-sensitive adhesive composition was changed to the composition (B-1) shown in Table 2B. An adhesive tape having a 25 μm adhesive layer formed on a polyethylene terephthalate film was produced, and the obtained adhesive tape was evaluated. There was almost no tack feeling of the obtained adhesive tape, and it was "1". The appearance 24 hours after the preparation of the adhesive tape was opaque, and the compatibility was poor and the value was "B". Further, no bleeding of the liquid substance was observed from the surface of the adhesive layer immediately after the production of the adhesive tape and 24 hours after the production, and the bleeding property was "a". Since it was prepared from a rosin ester that was not hydrogenated as a pressure-imparting resin, the color change of the obtained pressure-sensitive adhesive tape before and after treatment at 180 ° C. for 3 hours was large, and the thermal stability was "Δ". The evaluation results are shown in Table 2B.

[Comparative Examples 2 and 3]
Preparation of a toluene solution containing 40% by mass of the pressure-sensitive adhesive composition in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive composition is changed to the composition (B-2, B-3) shown in Table 2B, respectively. An adhesive tape having an adhesive layer having a thickness of 25 μm formed on a polyethylene terephthalate film was produced, and the obtained adhesive tape was evaluated. There was almost no tack feeling of the obtained adhesive tape, and it was "1". The appearance 24 hours after the preparation of the adhesive tape was opaque, and the compatibility was poor and the value was "B". Further, no bleeding of the liquid substance was observed from the surface of the adhesive layer immediately after the production of the adhesive tape and 24 hours after the production, and the bleeding property was "a". Since hydrogenated rosin ester and aromatic hydrocarbon resin were used as the tackifying resin, the color change of the obtained adhesive tape before and after treatment at 180 ° C. for 3 hours was small, and the thermal stability was "○". there were. The evaluation results are shown in Table 2B.

[Comparative Example 4]
Similar to Example 1, the preparation of a toluene solution containing 40% by mass of the pressure-sensitive adhesive composition and the thickness were increased, except that the composition of the pressure-sensitive adhesive composition was changed to the composition (B-4) shown in Table 2C. An adhesive tape having a 25 μm adhesive layer formed on a polyethylene terephthalate film was produced, and the obtained adhesive tape was evaluated. There was almost no tack feeling of the obtained adhesive tape, and it was "1". The appearance 24 hours after the preparation of the adhesive tape was transparent, and the compatibility was good "A". On the other hand, 24 hours after the preparation of the adhesive tape, oozing of the liquid material from the surface of the adhesive layer was observed, and the bleeding property was "b". Since the hydrogenated rosin ester was used as the pressure-imparting resin, the color change of the obtained pressure-sensitive adhesive tape before and after the treatment at 180 ° C. for 3 hours was small, and the thermal stability was “◯”. The evaluation results are shown in Table 2C.

[Example 36]
Table 2D shows the acrylic triblock copolymer (I-3) obtained in Production Example 3 and the acrylic triblock copolymer (I-2) obtained in Production Example 2 in a kneader set at 160 ° C. It was charged based on the compounding ratio and melted uniformly. After that, the temperature of the kneader was set to 145 ° C., "YS resin SX100" was added as a tackifier resin based on the compounding ratio shown in Table 2D, and the mixture was melt-kneaded until uniform, and then "ATBC" was added as a plasticizer. It was added based on the compounding ratios shown in Table 2D and melt-kneaded until uniform to obtain a viscous adhesive composition. The melt viscosities of the obtained adhesive composition were 217,000 mPa · s (160 ° C.) and 57,500 mPa · s (180 ° C.). The thickness of the adhesive layer was applied to the obtained adhesive composition on a polyethylene terephthalate film (Toyo Boseki Ester Film E5000, thickness 50 μm) using a non-contact hot melt coater (ITW Dynatec, cross coater). An adhesive tape having an adhesive layer formed on a polyethylene terephthalate film was produced by hot-melt coating at 170 ° C. so as to have a diameter of 25 μm.

The tackiness of the obtained adhesive tape was good, and it was "3". The appearance 24 hours after the preparation of the adhesive tape was transparent, and the compatibility was good "A". Further, no bleeding of the liquid substance was observed from the surface of the adhesive layer immediately after the production of the adhesive tape and 24 hours after the production, and the bleeding property was "a". Moreover, when the color change of the obtained adhesive tape before and after the heat treatment at 180 ° C. for 3 hours was evaluated, the color change could not be confirmed in appearance and the thermal stability was "◯". In addition, the holding force (creep) was only 0.5 mm, which was a high holding force. The evaluation results are shown in Table 2D.

[Examples 37 to 39]
The pressure-sensitive adhesive composition was prepared by melt-kneading in the same manner as in Example 36 except that the composition of the pressure-sensitive adhesive composition was changed to the composition (A-37 to A-39) shown in Table 2D. An adhesive tape having an adhesive layer having a thickness of 25 μm formed on a polyethylene terephthalate film was prepared using a hot melt coater (Cross coater manufactured by ITW Dynatec), and the obtained adhesive tape was evaluated. Only in Example 38, no plasticizer was added when the pressure-sensitive adhesive composition was prepared, and in Example 39, the melt coating temperature was set to 155 ° C. The evaluation results are shown in Table 2D.

As shown in the above examples, the appearance of the adhesive composition of the present invention and the adhesive tape obtained from the adhesive composition was transparent, there was no bleeding, and the adhesive properties were good. On the other hand, as in Comparative Examples 1 to 3, the adhesive composition containing the tackifier resin in an amount outside the range of the present invention and the adhesive tape obtained from the adhesive composition had a poor appearance and poor adhesive performance. Further, as in Comparative Example 4, the appearance of the adhesive composition containing the plasticizer in an amount outside the range of the present invention and the adhesive tape obtained from the adhesive tape is transparent and good, but the plasticizer bleeds on the tape surface. However, the adhesive performance was also poor. As in Examples 1-9, 13, 16-21, 24, 26-39, hydrogenated rosin ester, aromatic hydrocarbon resin, hydrogenated petroleum-based resin having excellent heat resistance as the tackifier resin. It can also be seen that when a resin is used, it is difficult to color even under high temperature storage, which is more preferable. Further, it can be seen that when the melt viscosity of the pressure-sensitive adhesive composition is high and no plasticizer is used as in Example 38, the holding power (creep resistance) of the obtained pressure-sensitive adhesive tape tends to be higher. It can be seen that even when a plasticizer is used as in Examples 36 and 37, when the melt viscosity of the pressure-sensitive adhesive composition is high, the holding power (creep resistance) of the obtained pressure-sensitive adhesive tape tends to be high.

From the above, it can be seen that the appearance of the adhesive composition of the present invention and the adhesive tape obtained from the adhesive composition is transparent, there is no bleeding, and excellent performance as adhesive properties is exhibited.

Claims (1)

(I) It has two polymer blocks (A1) and (A2) composed of methacrylic acid ester units and one polymer block (B) composed of acrylic acid ester units, and (A1)-(B)-( A2) Acrylic triblock having a block structure, a weight average molecular weight (Mw) of 50,000 to 250,000, and a total content of polymer blocks (A1) and (A2) of 35% by mass or less. A viscous adhesive composition containing 100 parts by mass of the copolymer (I) and 1 to 190 parts by mass of the tackifier resin (ii).
It contains only the acrylic triblock copolymer (I) as the acrylic block copolymer.
The adhesive composition contains only the acrylic triblock copolymer (I) and the tackifier resin .
The methacrylic ester serving as a constituent unit of the polymer blocks (A1) and (A2) is methyl methacrylate.
The acrylic acid ester serving as a constituent unit of the polymer block (B) is at least one selected from methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate and isooctyl acrylate.
Adhesive composition.