Adhesive agent composition, hot-melt adhesive agent composition, and adhesive agent

Abstract

Provided is an adhesive agent composition which contains an alkyl radical scavenger and a block copolymer composition containing a specific block copolymer A1 represented by general formula (1) and a specific block copolymer A2 represented by general formula (2), and in which the weight average molecular weight (Mw) of the entire block copolymer composition is 300,000-800,000, and the contained amount of the alkyl radical scavenger is 0.05-2 parts by mass with respect to 100 parts by mass of the contained amount of the block copolymer composition.

Description

Adhesive composition, hot melt adhesive composition and adhesive

[0001] The present invention relates to a pressure-sensitive adhesive composition, and a hot-melt pressure-sensitive adhesive composition and pressure-sensitive adhesive obtained using the pressure-sensitive adhesive composition.

[0002] Hot melt adhesives have the property of solidifying in a short time when cooled from a heated and molten state, making them capable of efficiently bonding a variety of products, and since they do not require solvents, they are adhesives that are highly safe for the human body, and are therefore used in a variety of fields.For example, hot melt adhesives are used as sealing adhesives for packaging paper, cardboard, and film for food, clothing, electronic devices, cosmetics, etc., as adhesives for bonding components that constitute sanitary products such as disposable diapers and sanitary products when they are produced, and as adhesives that constitute the adhesive layers of adhesive tapes and labels.

[0003] As a base polymer for constituting a hot melt pressure-sensitive adhesive, various thermoplastic resins are used, and for example, it is known to use an aromatic-conjugated diene copolymer such as a styrene-isoprene block copolymer or a styrene-butadiene block copolymer.

[0004] For example, Patent Document 1 discloses a composition containing a block copolymer containing an aromatic vinyl monomer unit, an antioxidant (I), an antioxidant (II), and an optional antioxidant (III), in which the antioxidant (I) is a compound containing a hindered phenol structure in which two ortho-positions of a hydroxyl group bonded to a benzene ring are substituted with t-butyl groups, the antioxidant (II) is a compound containing a sulfur atom in the molecule (excluding the antioxidant (I)), the antioxidant (III) is a polymer alkyl radical scavenger, and the antioxidant (III) is a polymer alkyl radical scavenger. the content of the antioxidant (I) is within a range of 0.05 to 1.00 parts by mass relative to 100 parts by mass of the block copolymer, the content of the antioxidant (II) is within a range of 0.10 to 1.00 parts by mass relative to 100 parts by mass of the block copolymer, the total content of the antioxidant (I), the antioxidant (II) and the antioxidant (III) is within a range of 0.15 to 1.50 parts by mass relative to 100 parts by mass of the block copolymer, and the content of conjugated diene dimer in the composition is 10 ppm by weight or less relative to the composition.

[0005] Japanese Patent Application Laid-Open No. 2020-117663

[0006] In recent years, there has been a demand for further improvement in adhesive properties, and there is a demand for a technique that can improve adhesive properties beyond those of Patent Document 1.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure-sensitive adhesive composition that has excellent processability and can provide a pressure-sensitive adhesive having excellent pressure-sensitive adhesive properties.

[0008] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a pressure-sensitive adhesive composition comprising a block copolymer composition containing a specific block copolymer A1 or a specific block copolymer A2 and having a total weight average molecular weight (Mw) of 300,000 to 800,000, and blending therewith a specific amount of an alkyl radical scavenger, and have thereby completed the present invention.

[0009] That is, according to the present invention, the following adhesive composition is provided.

[0010] [1] A pressure-sensitive adhesive composition comprising a block copolymer composition containing a block copolymer A1 represented by the following general formula (1) or a block copolymer A2 represented by the following general formula (2), and an alkyl radical scavenger, wherein the weight average molecular weight (Mw) of the entire block copolymer composition is 300,000 to 800,000, and the content of the alkyl radical scavenger is 0.05 to 2 parts by mass per 100 parts by mass of the content of the block copolymer composition. (Ar １ -D １ ) ｍ X １ (D ２ ) ｎ (1) (In general formula (1), Ar １ is an aromatic monovinyl polymer block, and D １ and D ２ are conjugated diene polymer blocks, m is an integer of 1 or more, n is an integer of 1 or more, and m+n is an integer of 3 or more; X １ is a residue of a multifunctional coupling agent. ｐ X (2) (In general formula (2), Ar is an aromatic monovinyl polymer block, D is a conjugated diene polymer block, p is an integer of 3 or more, and X is a residue of a polyfunctional coupling agent.)

[0011] [2] The pressure-sensitive adhesive composition according to [1], wherein the molecular weight distribution (Mw / Mn) of the block copolymer A1 or the block copolymer A2 is 1.40 or less, and the total content of the block copolymer A1 and the block copolymer A2 in the block copolymer composition is 10% by mass or more. [3] The pressure-sensitive adhesive composition according to [1] or [2], wherein the block copolymer composition further comprises a diblock copolymer B represented by the following general formula (3) or a polymer C represented by the following general formula (4), wherein the molecular weight distribution (Mw / Mn) of the diblock copolymer B or the polymer C is 1.20 or less, the total content of the diblock copolymer B and the polymer C in the block copolymer composition is 60% by mass or less, the content of aromatic monovinyl monomer units in the block copolymer composition is 5 to 40% by mass, and the type A hardness of the block copolymer composition measured using a durometer hardness tester (type A) in accordance with JIS K6253 is 25 to 65. ３ -D ３ (3) D ４ (4) (In the general formula (3) and the general formula (4), Ar ３ is an aromatic monovinyl polymer block, and D ３ and D ４ and each represent a conjugated diene polymer block.) [4] The pressure-sensitive adhesive composition according to any one of [1] to [3], which has a melt index of 1.5 to 50 g / 10 min measured in accordance with ASTM D1238 (G condition, 200°C, 5 kg load). [5] The block copolymer composition comprises the block copolymer A1, and D in the block copolymer A1 ２ Ar relative to the mass of the branched chain represented by １ -D １ The mass ratio of the branched chains ((Ar １ -D １ ) / D ２ [6] The pressure-sensitive adhesive composition according to any one of [1] to [4], wherein the ratio of D to D is 1.0 / 0.15 to 1.0 / 1.75. ２The weight average molecular weight (Mw(D ２ )) to Ar １ -D １ Conjugated diene polymer block D in the branched chain represented by １ Weight average molecular weight (Mw(D １ )) ratio ((Mw(D １ )) / (Mw(D ２ [7] The pressure-sensitive adhesive composition according to any one of [1] to [5], wherein the ratio of the t-butyl-2-hydroxybenzoate ratio to the alkyl radical scavenger ratio is 1.0 / 0.3 to 1.0 / 1.1. [8] The pressure-sensitive adhesive composition according to any one of [1] to [7], wherein the polyfunctional coupling agent is a compound having two or more radically polymerizable groups in the molecule. [9] The pressure-sensitive adhesive composition according to any one of [1] to [8], wherein the polyfunctional coupling agent is divinylbenzene.

[10] The pressure-sensitive adhesive composition according to any one of [1] to [9], wherein the conjugated diene polymer block is an isoprene polymer block.

[11] The pressure-sensitive adhesive composition according to any one of [1] to [9], wherein the alkyl radical scavenger is at least one selected from 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate and 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate.

[11] The pressure-sensitive adhesive composition according to any one of [1] to

[10] , further comprising at least one antioxidant selected from a hindered phenol-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, and a benzofuranone-based antioxidant, wherein the content of the antioxidant is 0.01 to 10 parts by mass relative to 100 parts by mass of the content of the block copolymer composition.

[0012] Furthermore, according to the present invention, there are provided the following hot melt adhesive composition and adhesive, which are produced using the above adhesive composition.

[0013]

[12] A hot-melt adhesive composition comprising the adhesive composition according to any one of [1] to

[11] , a tackifying resin, and a crosslinking agent, wherein the content of the tackifying resin is 10 to 400 parts by mass and the content of the crosslinking agent is 0.01 to 50 parts by mass relative to 100 parts by mass of the block copolymer composition in the adhesive composition.

[13] The hot-melt adhesive composition according to

[12] , which contains 0 to 200 parts by mass of a plasticizer relative to 100 parts by mass of the block copolymer composition in the adhesive composition.

[14] A adhesive comprising the hot-melt adhesive composition according to

[12] or

[13] , wherein the adhesive is obtained by crosslinking the block copolymer A1 or A2 in the hot-melt adhesive composition.

[0014] According to the present invention, it is possible to provide a composition for adhesives that has excellent processability and can give adhesives having excellent adhesive properties.

[0015] <Adhesive Composition> The adhesive composition of the present invention contains a block copolymer composition described below and an alkyl radical scavenger.

[0016] The adhesive composition of the present invention has excellent processability, can be suitably subjected to processing that applies a strong shear stress (for example, twin-screw extrusion processing), and can provide an adhesive having excellent hot-melt processability. Furthermore, in addition to excellent processability, the adhesive composition of the present invention has excellent crosslinkability, and can provide an adhesive having excellent adhesive properties (heat resistance stability, adhesion at high temperatures, and initial adhesion).

[0017] 1. Block Copolymer Composition The block copolymer composition used in the present invention contains a block copolymer A1 represented by general formula (1) or a block copolymer A2 represented by general formula (2), and the weight average molecular weight (Mw) of the entire block copolymer composition is 300,000 to 800,000. The block copolymer composition used in the present invention may contain either block copolymer A1 or block copolymer A2, or may contain both.

[0018] The block copolymer composition used in the present invention constitutes the polymer component containing a conjugated diene polymer block in the pressure-sensitive adhesive composition of the present invention, and contains a block copolymer A1 represented by general formula (1) or a block copolymer A2 represented by general formula (2).

[0019] (1-1) Block Copolymer A1 The block copolymer A1 is a block copolymer represented by the following general formula (1): (Ar １ -D １ ) ｍ X １ (D ２ ) ｎ (1) (In general formula (1), Ar １ is an aromatic monovinyl polymer block, and D １ and D ２ are conjugated diene polymer blocks, m is an integer of 1 or more, n is an integer of 1 or more, and m+n is an integer of 3 or more; X １ is a residue of a polyfunctional coupling agent.

[0020] In the general formula (1), Ar １ -D １ and D ２ are respectively, X １ and m is a branched chain bonded to X １ Ar bonded to １ -D １ n is the number of branched chains represented by X １ D bound to ２ m+n is the number of branched chains represented by Ar １ -D １ Branched chains represented by D ２The total number of branched chains represented by Ar represents the number of branches of the block copolymer A1. １ is an aromatic monovinyl polymer block, and D １ and D ２ is a conjugated diene polymer block.

[0021] In the general formula (1), m is an integer of 1 or more, n is an integer of 1 or more, and m+n is an integer of 3 or more. That is, the block copolymer A1 has a branched structure formed from three or more branched chains, and the branched chains include Ar １ -D １ A branched chain (a diblock chain containing an aromatic monovinyl polymer block and a conjugated diene polymer block) represented by the formula D ２ The branched chain (conjugated diene polymer block chain) includes both the branched chain represented by the formula:

[0022] In general formula (1), m+n is an integer of 3 or more, and is not particularly limited, but is preferably an integer of 4 to 20, more preferably an integer of 5 to 15, and even more preferably an integer of 6 to 10. When m+n is within the above range, the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive, can be further improved. m+n is an integer of 3 or more, and is not particularly limited, but is preferably an integer of 4 to 20, more preferably an integer of 5 to 15, and even more preferably an integer of 6 to 10. When m+n is within the above range, the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive can be further improved. １ -D １ Branched chains represented by D ２ The branched chain structure represented by the formula (I) and the coupling conditions (such as the type and amount of the polyfunctional coupling agent used) can be adjusted.

[0023] The block copolymer A1 may be composed of only one type of block copolymer having a substantially uniform structure, or may be composed of two or more types of block copolymers having substantially different structures.

[0024] Furthermore, the block copolymer A1 may be a mixture of block copolymers in which any of m, n, and m + n is different. When the average molecular weight of the block copolymer A1 is determined by measurement using high performance liquid chromatography (described later) and m, n, and m + n are calculated, the average values ​​of m, n, and m + n of multiple block copolymers in the mixture are calculated, and therefore these calculated values ​​may not necessarily be integers. However, in the present invention, integers that are closest to the calculated values ​​may be specified as m, n, and m + n.

[0025] (1-1-1) Aromatic monovinyl polymer block Ar １ Aromatic monovinyl polymer block Ar constituting block copolymer A1 １ is a polymer block having an aromatic monovinyl monomer unit as a constituent unit. １ The aromatic monovinyl monomer used to constitute the aromatic monovinyl monomer unit is not particularly limited as long as it is an aromatic vinyl compound having one radically polymerizable group, and examples thereof include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene, 2,4-dibromostyrene, and vinylnaphthalene. Among these, it is preferable to use styrene as the aromatic monovinyl monomer. These aromatic monovinyl monomers are used in the aromatic monovinyl polymer block Ar １ Each of these may be used alone or in combination of two or more.

[0026] Aromatic monovinyl polymer block Ar １may contain a monomer unit other than the aromatic monovinyl monomer unit. Examples of the monomer constituting the monomer unit other than the aromatic monovinyl monomer unit include a conjugated diene monomer such as 1,3-butadiene or isoprene (2-methyl-1,3-butadiene), an α,β-unsaturated nitrile monomer, an unsaturated carboxylic acid or acid anhydride monomer, an unsaturated carboxylic acid ester monomer, and a non-conjugated diene monomer. The aromatic monovinyl polymer block Ar １ The content of monomer units other than aromatic monovinyl monomer units in the above is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0027] Aromatic monovinyl polymer block Ar １ Weight average molecular weight (Mw(Ar １ ) is not particularly limited, but can be in the range of 7,000 to 18,000, preferably in the range of 7,500 to 17,000, and more preferably in the range of 8,000 to 16,000.

[0028] In the present invention, the weight average molecular weight (Mw) and number average molecular weight (Mn) of a polymer block, a branched chain, a block copolymer, a block copolymer composition, etc. are determined as polystyrene-equivalent values ​​measured by high performance liquid chromatography. More specifically, the weight average molecular weight and number average molecular weight are measured by the method described in the Examples.

[0029] (1-1-2) Conjugated diene polymer block D １ Conjugated diene polymer block D constituting block copolymer A1 １ is a polymer block having a conjugated diene monomer unit as a constituent unit. Conjugated diene polymer block D １The conjugated diene monomer used to constitute the conjugated diene monomer unit is not particularly limited as long as it is a conjugated diene compound, and examples thereof include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these conjugated diene monomers, it is preferable to use 1,3-butadiene and / or isoprene, and it is particularly preferable to use isoprene. Conjugated diene polymer block D １ is particularly preferably an isoprene polymer block. １ By constituting the conjugated diene polymer block D with isoprene monomer units, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive. １ In the above, each of them can be used alone or in combination of two or more thereof. １ A hydrogenation reaction may be carried out on a part of the unsaturated bonds of the conjugated diene polymer block D. １ may be a non-hydrogenated conjugated diene polymer block or a hydrogenated conjugated diene polymer block.

[0030] Conjugated diene polymer block D １ may contain a monomer unit other than the conjugated diene monomer unit. Examples of the monomer constituting the monomer unit other than the conjugated diene monomer unit include an aromatic monovinyl monomer such as styrene or α-methylstyrene, an α,β-unsaturated nitrile monomer, an unsaturated carboxylic acid or acid anhydride monomer, an unsaturated carboxylic acid ester monomer, and a non-conjugated diene monomer. Conjugated diene polymer block D １ The content of monomer units other than conjugated diene monomer units in the copolymer is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0031] Conjugated diene polymer block D １ Weight average molecular weight (Mw(D １)) is preferably in the range of 20,000 to 140,000, more preferably in the range of 25,000 to 120,000, and even more preferably in the range of 30,000 to 100,000.

[0032] (1-1-3) Ar １ -D １ Ar constituting the branched chain block copolymer A1 represented by １ -D １ The branched chain represented by the formula (I) may be produced by using any coupling agent, or may be produced without using any coupling agent. １ -D １ The branched chain represented by Ar may contain a residue of a coupling agent in each polymer block or between each polymer block, or may not contain a residue of a coupling agent. １ -D １ The branched chain represented by the formula (I) is preferably produced without using a coupling agent, and does not contain residues of a coupling agent in each polymer block or between each polymer block.

[0033] Ar １ -D １ The weight average molecular weight (Mw(Ar １ -D １ )) is preferably in the range of 30,000 to 150,000, more preferably in the range of 35,000 to 130,000, and even more preferably in the range of 40,000 to 110,000.

[0034] Ar １ -D １ The molecular weight distribution (Mw / Mn) of the branched chains represented by the formula (I) is preferably in the range of 1.20 or less, more preferably in the range of 1.00 to 1.20, even more preferably in the range of 1.00 to 1.18, particularly preferably in the range of 1.00 to 1.13, and particularly preferably in the range of 1.00 to 1.10.

[0035] (1-1-4) D２ D constituting the branched chain block copolymer A1 represented by ２ The branched chain represented by the formula (I) is a polymer block chain having conjugated diene monomer units as constituent units.

[0036] Conjugated diene polymer block D ２ The conjugated diene monomer used to constitute the conjugated diene monomer unit is not particularly limited as long as it is a conjugated diene compound, and examples thereof include 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these conjugated diene monomers, it is preferable to use 1,3-butadiene and / or isoprene, and it is particularly preferable to use isoprene. Conjugated diene polymer block D ２ is particularly preferably an isoprene polymer block. ２ By forming the branched chain represented by the formula (I) with isoprene monomer units, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the pressure-sensitive adhesive obtained. ２ In the branched chain represented by the formula (I), each of them can be used alone or in combination of two or more. ２ That is, a hydrogenation reaction may be carried out on a part of the unsaturated bonds of the branched chain represented by the following formula: ２ may be a non-hydrogenated conjugated diene polymer block or a hydrogenated conjugated diene polymer block.

[0037] D ２ The branched chain represented by the formula (I) may contain a monomer unit other than the conjugated diene monomer unit. Examples of the monomer constituting the monomer unit other than the conjugated diene monomer unit include an aromatic monovinyl monomer such as styrene or α-methylstyrene, an α,β-unsaturated nitrile monomer, an unsaturated carboxylic acid or acid anhydride monomer, an unsaturated carboxylic acid ester monomer, and a non-conjugated diene monomer. Conjugated diene polymer block D ２The content of monomer units other than conjugated diene monomer units in the copolymer is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0038] D ２ The weight average molecular weight (Mw(D ２ ) is not particularly limited, but is preferably in the range of 20,000 to 140,000, more preferably in the range of 25,000 to 120,000, and even more preferably in the range of 30,000 to 100,000.

[0039] (1-1-5) Residue X of a polyfunctional coupling agent １ Residue X of a polyfunctional coupling agent in block copolymer A1 １ Examples of the coupling agent that forms the formula include Ar １ -D １ Branched chains represented by D ２ and a block copolymer having a total of three or more branched chains.

[0040] Examples of polyfunctional coupling agents include silane compounds such as halogenated silanes such as tetrachlorosilane and tetrabromosilane, and alkoxysilanes such as tetramethoxysilane and tetraethoxysilane; tin compounds such as halogenated tin tetrachlorotin; epoxy compounds such as polycarboxylic acid esters and epoxidized soybean oil; and compounds having two or more radical polymerizable groups in the molecule. Among these, preferred are those capable of forming a polymer by reacting the coupling agents with each other, and more preferred are compounds having two or more radical polymerizable groups in the molecule.

[0041] Examples of compounds having two or more radically polymerizable groups in the molecule include radically polymerizable aromatic compounds having an aromatic ring and two or more radically polymerizable groups in the molecule, such as aromatic divinyl compounds, aromatic trivinyl compounds, and aromatic tetravinyl compounds; and radically polymerizable aliphatic compounds having an aliphatic group and two or more radically polymerizable groups in the molecule, such as pentaerythritol tetraacrylate. The radically polymerizable group is preferably a group containing a carbon-carbon double bond, and more preferably a vinyl group.

[0042] Specific examples of aromatic divinyl compounds include divinylbenzene (DVB), divinyltoluene, divinylxylene, divinylanthracene, divinylnaphthalene, divinyldurene, 1,2-bis(4-vinylphenyl)ethane, etc. Specific examples of aromatic trivinyl compounds include trivinylbenzene, etc. Specific examples of aromatic tetravinyl compounds include tetravinylbenzene, etc.

[0043] In the present invention, the polyfunctional coupling agent is preferably a compound having two or more radically polymerizable groups in the molecule, more preferably a radically polymerizable aromatic compound having an aromatic ring and two or more radically polymerizable groups in the molecule, even more preferably an aromatic divinyl compound, and particularly preferably divinylbenzene. By using these coupling agents, it is possible to easily obtain a block copolymer A1 having the number of branches (m+n) within the above-mentioned suitable range, and it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition and the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0044] (1-1-6) Block Copolymer A1 In the block copolymer A1, D ２ Ar relative to the mass of the branched chain represented by １ -D １ The mass ratio of the branched chains ((Ar １ -D １ ) / D ２) is not particularly limited, but is preferably 1.0 / 0.15 to 1.0 / 1.75, more preferably 1.0 / 0.20 to 1.0 / 1.25, even more preferably 1.0 / 0.25 to 1.0 / 0.75, and particularly preferably 1.0 / 0.25 to 1.0 / 0.5. １ -D １ ) / D ２ ) in the above range, the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive can be further improved.

[0045] In the block copolymer A1, D ２ The weight average molecular weight (Mw(D ２ )) to Ar １ -D １ Conjugated diene polymer block D in the branched chain represented by １ Weight average molecular weight (Mw(D １ )) ratio ((Mw(D １ )) / (Mw(D ２ ))) is not particularly limited, but is preferably 1.0 / 0.3 to 1.0 / 1.1, more preferably 1.0 / 0.5 to 1.0 / 1.07, even more preferably 1.0 / 0.7 to 1.0 / 1.05, and particularly preferably 1.0 / 0.9 to 1.0 / 1.03. １ )) / (Mw(D ２ By setting the above ranges, the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive can be further improved.

[0046] The weight-average molecular weight (MwA1) of the block copolymer A1 is preferably in the range of 300,000 to 800,000, more preferably in the range of 330,000 to 700,000, even more preferably in the range of 360,000 to 650,000, particularly preferably in the range of 380,000 to 600,000, and most preferably in the range of 400,000 to 550,000. By setting the weight-average molecular weight (MwA1) of the block copolymer A1 in the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0047] The molecular weight distribution (Mw / Mn) of the block copolymer A1 is preferably 1.40 or less, more preferably 1.00 to 1.30, even more preferably 1.00 to 1.20, particularly preferably 1.00 to 1.18, and most preferably 1.00 to 1.16. By setting the molecular weight distribution (Mw / Mn) of the block copolymer A1 within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the pressure-sensitive adhesive obtained.

[0048] The content of aromatic monovinyl monomer units in block copolymer A1 (the proportion of aromatic monovinyl monomer units to all monomer units constituting block copolymer A1) is preferably in the range of 5 to 40 mass%, more preferably in the range of 9 to 35 mass%, even more preferably in the range of 12 to 30 mass%, particularly preferably in the range of 15 to 28 mass%, and most preferably in the range of 18 to 26 mass%. By setting the content of aromatic monovinyl monomer units in block copolymer A1 within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0049] The vinyl bond content in the conjugated diene monomer units of the block copolymer A1 (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units constituting the block copolymer A1) is preferably in the range of 1 to 20% by mass, more preferably in the range of 1 to 15% by mass, and particularly preferably in the range of 1 to 10% by mass.

[0050] (1-2) Block Copolymer A2 The block copolymer composition used in the present invention may contain the block copolymer A2 described below instead of the block copolymer A1, or may contain the block copolymer A2 together with the block copolymer A1.

[0051] The block copolymer A2 is represented by the following general formula (2): (Ar-D) ｐ X (2) (in general formula (2), Ar is an aromatic monovinyl polymer block, D is a conjugated diene polymer block, p is an integer of 3 or more, and X is a residue of a polyfunctional coupling agent).

[0052] In general formula (2), Ar-D is a branched chain bonded to X, and p is the number of branched chains represented by Ar-D bonded to X, and therefore represents the number of branches in block copolymer A2. Also, Ar is an aromatic monovinyl polymer block, and D is a conjugated diene polymer block.

[0053] In general formula (2), p is an integer of 3 or greater. That is, block copolymer A2 has a branched structure formed from three or more branched chains, and the branched chains are branched chains represented by Ar-D (diblock chains containing an aromatic monovinyl polymer block and a conjugated diene polymer block).

[0054] In general formula (2), p is an integer of 3 or more, and is not particularly limited, but is preferably an integer of 4 to 20, more preferably an integer of 5 to 15, and even more preferably an integer of 6 to 10. When p is within the above range, the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive, can be further improved. p can be adjusted by adjusting the structure of the branched chain represented by Ar-D and the coupling conditions (such as the type and amount of the polyfunctional coupling agent used).

[0055] The block copolymer A2 may be composed of only one type of block copolymer having a substantially uniform structure, or may be composed of two or more types of block copolymers having substantially different structures.

[0056] Furthermore, the block copolymer A2 may be a mixture of block copolymers having different p values. When the average molecular weight of the block copolymer A2 is determined by measurement using high performance liquid chromatography, which will be described later, and p is calculated, the average value of p of the multiple block copolymers in the mixture is calculated, and therefore, these calculated values ​​may not necessarily be integers. However, in the present invention, the integer that is closest to the calculated value may be specified as p.

[0057] (1-2-1) Aromatic Monovinyl Polymer Block Ar The aromatic monovinyl polymer block Ar constituting the block copolymer A2 is a polymer block having an aromatic monovinyl monomer unit as a constituent unit. The aromatic monovinyl monomer used to constitute the aromatic monovinyl monomer unit of the aromatic monovinyl polymer block Ar is the aromatic monovinyl polymer block Ar of the block copolymer A1. １ Examples of the aromatic monovinyl monomers usable in the aromatic monovinyl polymer block Ar include those similar to the aromatic monovinyl monomers used to constitute the aromatic monovinyl monomer units in the above-mentioned formula (1), and among these, styrene is preferred. The aromatic monovinyl monomers can be used alone or in combination of two or more in the aromatic monovinyl polymer block Ar.

[0058] The aromatic monovinyl polymer block Ar may contain a monomer unit other than the aromatic monovinyl monomer unit. Examples of the monomer constituting the monomer unit other than the aromatic monovinyl monomer unit include a conjugated diene monomer such as 1,3-butadiene or isoprene (2-methyl-1,3-butadiene), an α,β-unsaturated nitrile monomer, an unsaturated carboxylic acid or acid anhydride monomer, an unsaturated carboxylic acid ester monomer, and a non-conjugated diene monomer. The content of the monomer unit other than the aromatic monovinyl monomer unit in the aromatic monovinyl polymer block Ar is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0059] The weight average molecular weight (Mw(Ar)) of the aromatic monovinyl polymer block Ar is not particularly limited, but can be within the range of 7,000 to 18,000, preferably within the range of 7,500 to 17,000, and more preferably within the range of 8,000 to 16,000.

[0060] (1-2-2) Conjugated diene polymer block D The conjugated diene polymer block D constituting the block copolymer A2 is a polymer block having a conjugated diene monomer unit as a constituent unit. The conjugated diene monomer used to constitute the conjugated diene monomer unit of the conjugated diene polymer block D is the same as that of the conjugated diene polymer block D of the block copolymer A1. １Examples of the conjugated diene monomers include those similar to those used to constitute the conjugated diene monomer units of (1), and among these, it is preferable to use 1,3-butadiene and / or isoprene, and it is particularly preferable to use isoprene. The conjugated diene polymer block D is particularly preferably an isoprene polymer block. By constituting the conjugated diene polymer block D with isoprene monomer units, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive. These conjugated diene monomers can be used alone or in combination of two or more in the conjugated diene polymer block D. Furthermore, a hydrogenation reaction may be performed on part of the unsaturated bonds of the conjugated diene polymer block D. That is, the conjugated diene polymer block D may be a non-hydrogenated conjugated diene polymer block or a hydrogenated conjugated diene polymer block.

[0061] The conjugated diene polymer block D may contain a monomer unit other than a conjugated diene monomer unit. Examples of the monomer constituting the monomer unit other than the conjugated diene monomer unit include an aromatic monovinyl monomer such as styrene or α-methylstyrene, an α,β-unsaturated nitrile monomer, an unsaturated carboxylic acid or acid anhydride monomer, an unsaturated carboxylic acid ester monomer, and a non-conjugated diene monomer. The content of the monomer unit other than the conjugated diene monomer unit in the conjugated diene polymer block D is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0062] The weight average molecular weight (Mw(D)) of the conjugated diene polymer block D is preferably in the range of 20,000 to 140,000, more preferably in the range of 25,000 to 120,000, and even more preferably in the range of 30,000 to 100,000.

[0063] (1-2-3) Branched Chain Represented by Ar-D The branched chain represented by Ar-D constituting the block copolymer A2 may be produced using any coupling agent, or may be produced without using a coupling agent. That is, the branched chain represented by Ar-D may contain a residue of a coupling agent in each polymer block or between each polymer block, or may not contain a residue of a coupling agent. From the viewpoint of being able to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition and the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive, it is preferred that the branched chain represented by Ar-D is produced without using a coupling agent and does not contain a residue of a coupling agent in each polymer block or between each polymer block.

[0064] The weight average molecular weight of the branched chain represented by Ar-D (Mw(Ar-D)) is preferably in the range of 30,000 to 150,000, more preferably in the range of 35,000 to 130,000, and even more preferably in the range of 40,000 to 110,000.

[0065] The molecular weight distribution (Mw / Mn) of the branched chains represented by Ar-D is preferably in the range of 1.20 or less, more preferably in the range of 1.00 to 1.20, even more preferably in the range of 1.00 to 1.18, particularly preferably in the range of 1.00 to 1.13, and particularly preferably in the range of 1.00 to 1.10.

[0066] (1-2-4) Residue X of Polyfunctional Coupling Agent The coupling agent that forms the residue X of the polyfunctional coupling agent in the block copolymer A2 may be any coupling agent that can bond with the branched chains represented by Ar-D to give a block copolymer having a total of three or more branched chains.

[0067] The polyfunctional coupling agent forming the residue X of the polyfunctional coupling agent is the residue X of the polyfunctional coupling agent in the block copolymer A1. １Examples of coupling agents that form the above-mentioned coupling agent include those mentioned above. The polyfunctional coupling agent is preferably a compound having two or more radically polymerizable groups in the molecule, more preferably a radically polymerizable aromatic compound having an aromatic ring and two or more radically polymerizable groups in the molecule, even more preferably an aromatic divinyl compound, and particularly preferably divinylbenzene. By using these coupling agents, it is possible to easily obtain a block copolymer A2 having a branch number (p) within the above-mentioned suitable range, and it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0068] (1-2-5) Block Copolymer A2 The weight average molecular weight (MwA2) of the block copolymer A2 is preferably in the range of 300,000 to 800,000, more preferably in the range of 340,000 to 750,000, even more preferably in the range of 380,000 to 700,000, particularly preferably in the range of 420,000 to 650,000, and most preferably in the range of 450,000 to 600,000. By setting the weight average molecular weight (MwA2) of the block copolymer A2 to be in the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0069] The molecular weight distribution (Mw / Mn) of the block copolymer A2 is preferably 1.40 or less, more preferably 1.00 to 1.30, even more preferably 1.00 to 1.20, particularly preferably 1.00 to 1.18, and most preferably 1.00 to 1.16. By setting the molecular weight distribution (Mw / Mn) of the block copolymer A2 within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the pressure-sensitive adhesive obtained.

[0070] The content of aromatic monovinyl monomer units in block copolymer A2 (the proportion of aromatic monovinyl monomer units to all monomer units constituting block copolymer A2) is preferably in the range of 5 to 40 mass%, more preferably in the range of 9 to 35 mass%, even more preferably in the range of 12 to 30 mass%, particularly preferably in the range of 15 to 28 mass%, and most preferably in the range of 18 to 26 mass%. By setting the content of aromatic monovinyl monomer units in block copolymer A2 within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0071] The vinyl bond content in the conjugated diene monomer units of block copolymer A2 (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units constituting block copolymer A2) is preferably in the range of 1 to 20 mass %, more preferably in the range of 1 to 15 mass %, and particularly preferably in the range of 1 to 10 mass %.

[0072] (1-3) Diblock Copolymer B The block copolymer composition used in the present invention may contain a diblock copolymer B in addition to the block copolymer A1 or the block copolymer A2.

[0073] The diblock copolymer B is represented by the following general formula (3): ３ -D ３ (3) (In formula (3), Ar ３ is an aromatic monovinyl polymer block, and D ３ is a conjugated diene polymer block.) It is a diblock copolymer represented by the formula:

[0074] When the block copolymer composition contains the block copolymer A1, the diblock copolymer B is usually the same as Ar constituting the block copolymer A1. １ -D １ In this case, the aromatic monovinyl polymer block Ar constituting the diblock copolymer B has a similar structure to the branched chain represented by the formula (I), but it may have a different structure. ３ and conjugated diene polymer block D ３Regarding the aromatic monovinyl polymer block Ar in the block copolymer A1, １ and conjugated diene polymer block D １ According to the method for producing the block copolymer A1 described later, the structure of the diblock copolymer B is usually the same as that of Ar constituting the block copolymer A1. １ -D １ The branched chain may have the same structure as that represented by the following formula:

[0075] When the block copolymer composition contains block copolymer A2, diblock copolymer B usually has the same structure as the branched chain represented by Ar-D constituting block copolymer A2, but it may have a different structure. In this case, the aromatic monovinyl polymer block Ar constituting diblock copolymer B ３ and conjugated diene polymer block D ３ can be the same as the aromatic monovinyl polymer block Ar and the conjugated diene polymer block D in the block copolymer A2, and the preferred embodiments are also the same. According to the production method of the block copolymer A2 described later, the structure of the diblock copolymer B can usually be the same as the structure of the branched chain represented by Ar-D constituting the block copolymer A2.

[0076] The diblock copolymer B may be produced using any coupling agent, or may be produced without using a coupling agent, but it is preferable that the diblock copolymer B does not contain residues of a coupling agent in each polymer block or between each polymer block.

[0077] The weight average molecular weight (MwB) of the diblock copolymer B is preferably in the range of 30,000 to 150,000, more preferably in the range of 35,000 to 130,000, and even more preferably in the range of 40,000 to 110,000.

[0078] The molecular weight distribution (Mw / Mn) of the diblock copolymer B is preferably in the range of 1.20 or less, more preferably in the range of 1.00 to 1.20, even more preferably in the range of 1.00 to 1.18, particularly preferably in the range of 1.00 to 1.13, and particularly preferably in the range of 1.00 to 1.10.

[0079] The content of aromatic monovinyl monomer units in diblock copolymer B (the proportion of aromatic monovinyl monomer units relative to all monomer units constituting diblock copolymer B) is preferably within the range of 5 to 40 mass%, more preferably within the range of 9 to 35 mass%, even more preferably within the range of 12 to 30 mass%, particularly preferably within the range of 15 to 28 mass%, and most preferably within the range of 18 to 26 mass%.

[0080] The vinyl bond content in the conjugated diene monomer units of the diblock copolymer B (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units constituting the diblock copolymer B) is preferably in the range of 1 to 20% by mass, more preferably in the range of 1 to 15% by mass, and particularly preferably in the range of 1 to 10% by mass.

[0081] The diblock copolymer B constituting the block copolymer composition used in the present invention may be composed of only one type of diblock copolymer B having a substantially uniform structure, or may be composed of two or more types of diblock copolymers B having substantially different structures.

[0082] (1-4) Polymer C The block copolymer composition used in the present invention may contain polymer C in addition to block copolymer A1 or block copolymer A2 and, if necessary, diblock copolymer B. In one embodiment of the present invention, the block copolymer composition may consist only of block copolymer A1, block copolymer A2, diblock copolymer B, and polymer C, or may consist only of block copolymer A1, diblock copolymer B, and polymer C, or may consist only of block copolymer A2, diblock copolymer B, and polymer C.

[0083] The polymer C is represented by the following general formula (4): ４ (4) (In formula (4), D ４ is a conjugated diene polymer block.) It is a conjugated diene polymer having conjugated diene monomer units as constituent units.

[0084] Polymer C is a conjugated diene polymer having a conjugated diene monomer unit as a constituent unit. The conjugated diene monomer used to constitute the conjugated diene monomer unit of polymer C is conjugated diene polymer block D constituting block copolymer A1. ２ Examples of the conjugated diene monomer used to form the conjugated diene polymer block D include those mentioned above. Among them, 1,3-butadiene and / or isoprene are preferred, and isoprene is particularly preferred. ４ is particularly preferably an isoprene polymer block. By constituting polymer C with isoprene monomer units, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive. These conjugated diene monomers can be used in polymer C either alone or in combination of two or more. Furthermore, a hydrogenation reaction may be carried out on part of the unsaturated bonds of polymer C. That is, conjugated diene polymer block D ４ may be a non-hydrogenated conjugated diene polymer block or a hydrogenated conjugated diene polymer block.

[0085] Polymer C may contain a monomer unit other than a conjugated diene monomer unit. Examples of the monomer constituting the monomer unit other than a conjugated diene monomer unit include an aromatic monovinyl monomer such as styrene or α-methylstyrene, an α,β-unsaturated nitrile monomer, an unsaturated carboxylic acid or acid anhydride monomer, an unsaturated carboxylic acid ester monomer, and a non-conjugated diene monomer. The content of the monomer unit other than a conjugated diene monomer unit in Polymer C is preferably 20% by mass or less, more preferably 10% by mass or less, and particularly preferably substantially 0% by mass.

[0086] When the block copolymer composition contains the block copolymer A1, the polymer C is usually a conjugated diene polymer block D constituting the block copolymer A1. ２ When the block copolymer composition contains the block copolymer A1, the polymer C has a similar structure to the conjugated diene polymer block D in the block copolymer A1, but may have a different structure. ２ According to the method for producing the block copolymer A1 described later, the structure of the polymer C is usually the same as that of the conjugated diene polymer block D constituting the block copolymer A1. ２ It can have a similar configuration.

[0087] The weight average molecular weight (MwC) of polymer C is preferably in the range of 20,000 to 140,000, more preferably in the range of 25,000 to 120,000, and even more preferably in the range of 30,000 to 100,000.

[0088] The molecular weight distribution (Mw / Mn) of polymer C is preferably in the range of 1.20 or less, more preferably in the range of 1.00 to 1.20, even more preferably in the range of 1.00 to 1.18, particularly preferably in the range of 1.00 to 1.13, and particularly preferably in the range of 1.00 to 1.10. By setting the molecular weight distribution (Mw / Mn) of polymer C in the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the pressure-sensitive adhesive to be obtained.

[0089] The vinyl bond content in the conjugated diene monomer units of polymer C (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units constituting polymer C) is preferably in the range of 1 to 20 mass%, more preferably in the range of 1 to 15 mass%, and particularly preferably in the range of 1 to 10 mass%.

[0090] The polymer C may be composed of only one type of polymer C having a substantially uniform structure, or may be composed of two or more types of polymer C having substantially different structures.

[0091] (1-5) Block Copolymer Composition The block copolymer composition used in the present invention contains, in addition to the above-mentioned block copolymer A1 or block copolymer A2, a diblock copolymer B and a polymer C, as necessary, and the weight average molecular weight (Mw) of the entire block copolymer composition is 300,000 to 800,000.

[0092] In the present invention, the weight average molecular weight (Mw) of the entire block copolymer composition means the weight average molecular weight (Mw) of all polymer components, including the conjugated diene polymer block, that constitute the block copolymer composition. For example, when the block copolymer composition is composed of block copolymer A1, block copolymer A2, diblock copolymer B, and polymer C, the weight average molecular weight (Mw) of the entire block copolymer composition means the weight average molecular weight (Mw) of all polymer components composed of block copolymer A1, block copolymer A2, diblock copolymer B, and polymer C.

[0093] The weight-average molecular weight (Mw) of the entire block copolymer composition used in the present invention is within the range of 300,000 to 800,000. When the weight-average molecular weight (Mw) of the entire block copolymer composition is within the above range, the pressure-sensitive adhesive composition of the present invention has excellent processability and can provide a pressure-sensitive adhesive having excellent pressure-sensitive adhesive properties. From the viewpoint of further improving the processability and crosslinkability of the pressure-sensitive adhesive composition and the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive, the weight-average molecular weight (Mw) of the entire block copolymer composition is preferably within the range of 320,000 to 750,000, more preferably within the range of 340,000 to 700,000, even more preferably within the range of 360,000 to 650,000, and particularly preferably within the range of 380,000 to 600,000.

[0094] The molecular weight distribution of the entire block copolymer composition, represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferably within a range of 1.01 to 2.50, more preferably within a range of 1.02 to 2.20, and even more preferably within a range of 1.02 to 2.0.

[0095] When the block copolymer composition contains block copolymer A1, the content of block copolymer A1 in the block copolymer composition is preferably in the range of 10% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, particularly preferably 80 to 99% by mass, and most preferably 90 to 98% by mass, when the total mass of the block copolymer composition is taken as 100% by mass. By setting the content of block copolymer A1 in the block copolymer composition within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0096] When the block copolymer composition contains block copolymer A2, the content of block copolymer A2 in the block copolymer composition is preferably in the range of 10% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, particularly preferably 80 to 99% by mass, and most preferably 90 to 98% by mass, when the total mass of the block copolymer composition is taken as 100% by mass. By setting the content of block copolymer A2 in the block copolymer composition within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0097] The total content of block copolymer A1 and block copolymer A2 in the block copolymer composition is preferably in the range of 10% by mass or more, more preferably 40% by mass or more, even more preferably 60% by mass or more, particularly preferably 80 to 99% by mass, and most preferably 90 to 98% by mass, when the total mass of the block copolymer composition is taken as 100% by mass. By setting the total content of block copolymer A1 and block copolymer A2 in the block copolymer composition within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive.

[0098] The content of diblock copolymer B in the block copolymer composition is preferably in the range of 60% by mass or less, more preferably in the range of 40% by mass or less, even more preferably in the range of 20% by mass or less, particularly preferably in the range of 0.5 to 15% by mass, and most preferably in the range of 1 to 10% by mass, when the total mass of the block copolymer composition is taken as 100% by mass. By setting the content of diblock copolymer B in the block copolymer composition within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0099]

[0044] The content of polymer C in the block copolymer composition is preferably in the range of 60% by mass or less, more preferably in the range of 40% by mass or less, even more preferably in the range of 20% by mass or less, particularly preferably in the range of 0.5 to 15% by mass, and most preferably in the range of 1 to 10% by mass, when the total mass of the block copolymer composition is taken as 100% by mass. By setting the content of polymer C in the block copolymer composition within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0100] The total content of the diblock copolymer B and the polymer C in the block copolymer composition is preferably in the range of 90% by mass or less, more preferably in the range of 60% by mass or less, even more preferably in the range of 40% by mass or less, particularly preferably in the range of 1 to 20% by mass, and most preferably in the range of 2 to 10% by mass, when the total mass of the block copolymer composition is taken as 100% by mass. By setting the total content of the diblock copolymer B and the polymer C in the block copolymer composition within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0101] When the block copolymer composition contains block copolymer A1, the ratio of the contents of block copolymer A1, diblock copolymer B, and polymer C in the block copolymer composition (content of block copolymer A1 / content of diblock copolymer B / content of polymer C) is preferably 10 to 100 / 0 to 60 / 0 to 60, more preferably 40 to 100 / 0 to 40 / 0 to 40, still more preferably 60 to 100 / 0 to 20 / 0 to 20, particularly preferably 80 to 99 / 0.5 to 15 / 0.5 to 15, and most preferably 90 to 98 / 1 to 10 / 1 to 10, based on mass.

[0102] When the block copolymer composition contains block copolymer A2, the ratio of the contents of block copolymer A2, diblock copolymer B, and polymer C in the block copolymer composition (content of block copolymer A2 / content of diblock copolymer B / content of polymer C) is preferably 10 to 100 / 0 to 60 / 0 to 60, more preferably 40 to 100 / 0 to 40 / 0 to 40, still more preferably 60 to 100 / 0 to 20 / 0 to 20, particularly preferably 80 to 99 / 0.5 to 15 / 0.5 to 15, and most preferably 90 to 98 / 1 to 10 / 1 to 10, based on mass.

[0103] The ratio of the total content of block copolymer A1 and block copolymer A2, the content of diblock copolymer B, and the content of polymer C in the block copolymer composition (total content of block copolymer A1 and block copolymer A2 / content of diblock copolymer B / content of polymer C) is, by mass, preferably 10 to 100 / 0 to 60 / 0 to 60, more preferably 40 to 100 / 0 to 40 / 0 to 40, even more preferably 60 to 100 / 0 to 20 / 0 to 20, particularly preferably 80 to 99 / 0.5 to 15 / 0.5 to 15, and most preferably 90 to 98 / 1 to 10 / 1 to 10,

[0104]

[0033] The content of aromatic monovinyl monomer units in the block copolymer composition, i.e., the proportion of aromatic monovinyl monomer units relative to the total amount of the block copolymer composition, i.e., the proportion of aromatic monovinyl monomer units relative to all block copolymer components of the block copolymer composition (hereinafter, this may be referred to as the "total aromatic monovinyl monomer unit content") is preferably in the range of 5 to 40 mass%, more preferably in the range of 9 to 35 mass%, even more preferably in the range of 12 to 30 mass%, particularly preferably in the range of 15 to 28 mass%, and most preferably in the range of 18 to 26 mass%. By setting the total aromatic monovinyl monomer unit content within the above range, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0105] The total aromatic monovinyl monomer unit content can be easily adjusted by taking into account the aromatic monovinyl monomer unit content of each polymer that constitutes block copolymer composition and adjusting the blending amount of each polymer.In addition, if all the polymer components that constitute block copolymer composition are only composed of aromatic monovinyl monomer unit and conjugated diene monomer unit, according to the method described in Rubber Chem.Technol., 45,1295 (1972), by ozonolysis of polymer components, and then reducing with lithium aluminum hydride, conjugated diene monomer unit part is decomposed, and only aromatic monovinyl monomer unit part can be extracted, so that the total aromatic monovinyl monomer unit content can be easily measured.

[0106] The vinyl bond content in the conjugated diene monomer units in the block copolymer composition (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units constituting the block copolymer composition) is preferably in the range of 1 to 20 mass %, more preferably in the range of 1 to 15 mass %, and particularly preferably in the range of 1 to 10 mass %.

[0107] The Type A hardness of the block copolymer composition is preferably 25 to 65, more preferably 26 to 64, and even more preferably 27 to 63. When the Type A hardness of the block copolymer composition is within the above range, the processability of the pressure-sensitive adhesive composition can be further improved. The Type A hardness is a value measured using a durometer hardness tester (Type A) in accordance with JIS K6253.

[0108] The content of the block copolymer composition in the pressure-sensitive adhesive composition is preferably 90 to 99.95 mass%, more preferably 93 to 99.9 mass%, even more preferably 96 to 99.85 mass%, particularly preferably 98 to 99.8 mass%, and most preferably 99 to 99.75 mass%, which can further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the resulting pressure-sensitive adhesive.

[0109] 2. Alkyl Radical Scavenger The pressure-sensitive adhesive composition of the present invention contains an alkyl radical scavenger in addition to the block copolymer composition.

[0110] The alkyl radical scavenger used in the present invention is a compound that captures alkyl radicals generated from polymer components. The alkyl radicals may be alkyl radicals generated by cleavage of the main chain or side chain of a polymer component such as a block copolymer by heat, light, or the like.

[0111] As the alkyl radical scavenger, a compound containing an acryloyl group or a methacryloyl group in the molecule is preferred, and a compound containing an acryloyl group or a methacryloyl group and a hydroxyphenyl group in the molecule is more preferred. The hydroxyphenyl group may be a hydroxyphenyl group in which at least one of the two ortho positions of the hydroxyl group bonded to the benzene ring is substituted with a group containing two or more carbon atoms. As the alkyl radical scavenger, at least one selected from 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate and 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate is more preferred. These may be used alone or in combination of two or more.

[0112] The content of the alkyl radical scavenger in the pressure-sensitive adhesive composition is 0.05 to 2 parts by mass relative to 100 parts by mass of the content of the block copolymer composition in the pressure-sensitive adhesive composition. If the content of the alkyl radical scavenger is too low, the processability is poor, processing that applies a strong shear stress (for example, twin-screw extrusion) cannot be suitably carried out, and the obtained hot-melt pressure-sensitive adhesive composition will have poor hot-melt processability. On the other hand, if the content of the alkyl radical scavenger is too high, the crosslinkability will be poor, and the obtained pressure-sensitive adhesive will have poor pressure-sensitive adhesive properties.

[0113] In the present invention, the phrase "the content of the alkyl radical scavenger is 0.05 to 2 parts by mass relative to 100 parts by mass of the content of the block copolymer composition" means "the content of the alkyl radical scavenger is 0.05 to 2 parts by mass relative to 100 parts by mass of the total content of polymer components (block copolymer composition) containing conjugated diene polymer blocks in the composition for pressure-sensitive adhesive." For example, when the polymer components (block copolymer composition) containing conjugated diene polymer blocks in the composition for pressure-sensitive adhesive consist only of block copolymer A1, block copolymer A2, diblock copolymer B and polymer C, the phrase "the content of the alkyl radical scavenger is 0.05 to 2 parts by mass relative to 100 parts by mass of the content of the block copolymer composition" means "the content of the alkyl radical scavenger is 0.05 to 2 parts by mass relative to 100 parts by mass of the total content of block copolymer A1, block copolymer A2, diblock copolymer B and polymer C in the composition for pressure-sensitive adhesive." Hereinafter, with regard to the content of each component other than the alkyl radical scavenger, the expression "per 100 parts by mass of the content of the block copolymer composition" can be read as "per 100 parts by mass of the total content of polymer components (block copolymer composition) including the conjugated diene polymer block."

[0114] The content of the alkyl radical scavenger in the pressure-sensitive adhesive composition is not particularly limited as long as it is 0.05 to 2 parts by mass relative to 100 parts by mass of the block copolymer composition in the pressure-sensitive adhesive composition, but is preferably 0.1 to 1.5 parts by mass, more preferably 0.15 to 1 part by mass, even more preferably 0.18 to 0.8 parts by mass, and particularly preferably 0.2 to 0.5 parts by mass relative to 100 parts by mass of the block copolymer composition. By setting the content of the alkyl radical scavenger in the pressure-sensitive adhesive composition within the above ranges, it is possible to further improve the processability and crosslinkability of the pressure-sensitive adhesive composition, as well as the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive.

[0115] 3. Antioxidant The pressure-sensitive adhesive composition of the present invention preferably contains an antioxidant in addition to the block copolymer composition and alkyl radical scavenger. Examples of the antioxidant include hindered phenol-based antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, and benzofuranone-based antioxidants. The pressure-sensitive adhesive composition of the present invention may consist solely of the block copolymer composition, alkyl radical scavenger, and antioxidant.

[0116] (3-1) Hindered Phenol-Based Antioxidants Examples of the hindered phenol-based antioxidants include compounds having a hydroxyphenyl group in which at least one of the two ortho-positions of a hydroxyl group bonded to a benzene ring is substituted with a group containing two or more carbon atoms.

[0117] Specific examples of the hindered phenol antioxidant include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, 3-(3,5-di-tert-butyl-4- hydroxyphenyl) stearyl propionate, 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene, tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane, 2,6-di-t-butyl-4-((4,6-bis(octylthio)-1,3,5-triazin-2-yl)amino)-phenol, and the like. Among these, pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate] and 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol are preferred, and pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate] and 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol are more preferred.

[0118] The content of the hindered phenol-based antioxidant in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 0 to 5 parts by mass, more preferably 0.01 to 2 parts by mass, even more preferably 0.02 to 1 part by mass, particularly preferably 0.05 to 0.5 parts by mass, and most preferably 0.1 to 0.3 parts by mass, relative to 100 parts by mass of the block copolymer composition in the pressure-sensitive adhesive composition. By setting the content of the hindered phenol-based antioxidant within the above range, the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive can be further improved.

[0119] (3-2) Phosphorus-Based Antioxidants Examples of phosphorus-based antioxidants include monophosphite compounds and diphosphite compounds.

[0120] Specific examples of the monophosphite compound include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl)phosphite, tris(dinonylphenyl)phosphite, tris(2,4-di-t-butylphenyl)phosphite, tris(2-t-butyl-4-methylphenyl)phosphite, tris(cyclohexylphenyl)phosphite, 2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene.

[0121] Specific examples of diphosphite compounds include 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl phosphite), 4,4'-isopropylidene-bis(phenyl-di-alkyl(C12 to C15) phosphite), 4,4'-isopropylidene-bis(diphenyl monoalkyl(C12 to C15) phosphite), 1,1,3-tris(2-methyl-4-di-tridecyl phosphite-5-t-butylphenyl)butane, tetrakis(2,4-di-t-butylphenyl)-4,4 and diphosphite compounds such as cyclic neopentanetetraylbis(isodecyl phosphite), cyclic neopentanetetraylbis(nonylphenyl phosphite), cyclic neopentanetetraylbis(2,4-di-t-butylphenyl phosphite), cyclic neopentanetetraylbis(2,4-dimethylphenyl phosphite), and cyclic neopentanetetraylbis(2,6-di-t-butylphenyl phosphite).

[0122] Among these, monophosphite compounds are preferred, and tris(nonylphenyl)phosphite, tris(dinonylphenyl)phosphite and tris(2,4-di-t-butylphenyl)phosphite are more preferred.

[0123] The content of the phosphorus-based antioxidant in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 0 to 5 parts by mass, more preferably 0.01 to 2 parts by mass, even more preferably 0.02 to 1 part by mass, particularly preferably 0.05 to 0.5 parts by mass, and most preferably 0.1 to 0.3 parts by mass, relative to 100 parts by mass of the block copolymer composition in the pressure-sensitive adhesive composition. By setting the content of the phosphorus-based antioxidant within the above range, the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive can be further improved.

[0124] (3-3) Sulfur-Based Antioxidants Examples of sulfur-based antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, laurylstearyl 3,3-thiodipropionate, pentaerythritol-tetrakis-(β-lauryl-thio-propionate), 3,9-bis(2-dodecylthioethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, and the like.

[0125] The content of the sulfur-based antioxidant in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 0 to 5 parts by mass, more preferably 0.01 to 2 parts by mass, even more preferably 0.02 to 1 part by mass, particularly preferably 0.05 to 0.5 parts by mass, and most preferably 0.1 to 0.3 parts by mass, relative to 100 parts by mass of the block copolymer composition in the pressure-sensitive adhesive composition. By setting the content of the sulfur-based antioxidant within the above range, the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive can be further improved.

[0126] (3-4) Benzofuranone-Based Antioxidants The benzofuranone-based antioxidant may be any compound having a benzofuranone skeleton, and is preferably a 3-arylbenzofuran-2-one having a benzofuranone skeleton and further having an aryl group as a substituent on the side chain of the furan ring. Specific examples of benzofuranone-based antioxidants include 5,7-di-tert-butyl-3-(3,4-dimethylphenyl)-3H-benzofuran-2-one.

[0127] The content of the benzofuranone-based antioxidant in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 0 to 5 parts by mass, more preferably 0.01 to 2 parts by mass, even more preferably 0.02 to 1 part by mass, particularly preferably 0.05 to 0.5 parts by mass, and most preferably 0.1 to 0.3 parts by mass, relative to 100 parts by mass of the block copolymer composition in the pressure-sensitive adhesive composition. By setting the content of the benzofuranone-based antioxidant within the above range, the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive can be further improved.

[0128] (3-5) Antioxidant The antioxidant is preferably at least one selected from a hindered phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant, and more preferably at least one selected from a hindered phenol-based antioxidant and a phosphorus-based antioxidant. The antioxidant may be used alone or in combination of two or more. For example, one or more hindered phenol-based antioxidants may be used as the antioxidant, or a hindered phenol-based antioxidant and a phosphorus-based antioxidant may be used in combination as the antioxidant.

[0129] The content of the antioxidant in the pressure-sensitive adhesive composition (when two or more types of antioxidants are used, the total content of these antioxidants) is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, even more preferably 0.1 to 2 parts by mass, particularly preferably 0.15 to 1 part by mass, and most preferably 0.2 to 0.5 parts by mass, relative to 100 parts by mass of the block copolymer composition in the pressure-sensitive adhesive composition. By setting the content of the antioxidant within the above range, the pressure-sensitive adhesive properties of the obtained pressure-sensitive adhesive can be further improved.

[0130] 4. Pressure-sensitive adhesive composition The melt index of the pressure-sensitive adhesive composition of the present invention, as a value measured in accordance with ASTM D1238 (G conditions, 200°C, 5 kg load), is preferably in the range of 1.5 to 50 g / 10 min, more preferably in the range of 2 to 40 g / 10 min, even more preferably in the range of 3 to 30 g / 10 min, and particularly preferably in the range of 4 to 20 g / 10 min. By setting the melt index of the pressure-sensitive adhesive composition within the above range, the processability of the pressure-sensitive adhesive composition can be further improved. The melt index of the pressure-sensitive adhesive composition can be adjusted by adjusting the molecular weight and monomer composition of each polymer constituting the block copolymer composition, the weight average molecular weight of the entire block copolymer composition, etc.

[0131]

[0033] 5. Manufacturing Method of Pressure-Sensitive Adhesive Composition

[0034] A suitable example of a manufacturing method of a pressure-sensitive adhesive composition of the present invention is a manufacturing method comprising: a solution preparation step of preparing a solution of a block copolymer composition containing block copolymer A1 or block copolymer A2; an addition step of adding an alkyl radical scavenger to the solution of block copolymer composition obtained in the solution preparation step to obtain a mixed solution; and a recovery step of removing the solvent from the mixed solution obtained in the addition step to recover a solid pressure-sensitive adhesive composition. Such a manufacturing method will be described below.

[0132] (5-1) Solution Preparation Step In the solution preparation step, the method for preparing a solution of a block copolymer composition containing block copolymer A1 or block copolymer A2 is not particularly limited. For example, a polymerization solution containing the block copolymer composition may be obtained by polymerizing monomers for forming the block copolymer composition, and this polymerization solution may be used as a solution of the block copolymer composition in the adding step described below. Alternatively, a solid block copolymer composition may be obtained by any method, and then the solid block copolymer composition may be dissolved in a solvent to obtain a solution of the block copolymer composition, and this solution may be used in the adding step described below. As a method for preparing a solution of the block copolymer composition, the method for producing a block copolymer composition containing block copolymer A1 or the method for producing a block copolymer composition containing block copolymer A2 described below is preferred.

[0133] The block copolymer composition used in the present invention can be produced all at once by the production method described below, but it may also be produced by preparing block copolymer A1 or block copolymer A2 and arbitrarily mixing separately prepared diblock copolymer B, polymer C, and block copolymer D.

[0134] (5-1-1) Method for Producing a Block Copolymer Composition Containing Block Copolymer A1 Suitable examples of the method for producing a block copolymer composition containing block copolymer A1 include a production method comprising: a polymerization step of polymerizing an aromatic monovinyl monomer in a polymerization solvent using an organolithium initiator to obtain an aromatic monovinyl polymer block chain; a polymerization step of polymerizing a conjugated diene monomer in the presence of the aromatic monovinyl polymer block chain in a polymerization solvent using an organolithium initiator to obtain a diblock chain and a conjugated diene polymer block chain; and a coupling step of reacting the diblock chain and the conjugated diene polymer block chain with a polyfunctional coupling agent.

[0135] (Polymerization Step) The organolithium initiator used in the polymerization step can be any known initiator capable of initiating the polymerization of an aromatic monovinyl monomer and a conjugated diene monomer. Specific examples include organomonolithium initiators such as methyllithium, n-propyllithium, n-butyllithium, and sec-butyllithium. Among these, n-butyllithium is preferred. The amount of organolithium initiator used may be calculated according to the molecular weight of the desired polymer using a method well known to those skilled in the art. In the present invention, the use of an organolithium initiator allows the polymerization reaction to proceed with living properties, resulting in the presence of a polymer having an active end in the polymerization reaction system. Therefore, in the present invention, the polymer chain obtained in the polymerization step can be one having an active end.

[0136] The polymerization solvent is not particularly limited as long as it is inert to the organolithium initiator, and examples thereof include open-chain hydrocarbon solvents, cyclic hydrocarbon solvents, and mixtures thereof. Examples of open-chain hydrocarbon solvents include n-butane, isobutane, n-hexane, or mixtures thereof; 1-butene, isobutylene, trans-2-butene, cis-2-butene, or mixtures thereof; 1-pentene, trans-2-pentene, cis-2-pentene, or mixtures thereof; n-pentane, isopentane, neo-pentane, or mixtures thereof; and 1-pentene, trans-2-pentene, cis-2-pentene, or mixtures thereof. Examples of cyclic hydrocarbon solvents include aromatic hydrocarbons such as benzene, toluene, and xylene; and alicyclic hydrocarbons such as cyclohexane. From the viewpoint of controlling the polymerization temperature and the molecular weight distribution, it is preferable to use a mixture of an open-chain hydrocarbon solvent and a cyclic hydrocarbon solvent, and these are used in a mass ratio of "open-chain hydrocarbon solvent:cyclic hydrocarbon solvent" of preferably 5:95 to 50:50, more preferably 10:90 to 40:60.

[0137] The polymerization reaction can also be carried out in the presence of a polar compound. The use of a polar compound can adjust the polymerization initiation rate and molecular weight distribution. Examples of polar compounds include aromatic or aliphatic ethers or tertiary amines having a dielectric constant (25°C) of 2.5 to 5.0. Specific examples of polar compounds include aromatic ethers such as diphenyl ether and anisole; aliphatic ethers such as diethyl ether and dibutyl ether; tertiary monoamines such as trimethylamine, triethylamine, and tripropylamine; and tertiary polyamines such as tetramethylethylenediamine and tetraethylethylenediamine. These polar compounds can be used alone or in combination of two or more. The amount of polar compound used is preferably 0.001 to 50 moles, more preferably 0.005 to 10 moles, per mole of organolithium initiator.

[0138] The method for polymerizing the aromatic monovinyl monomer is not particularly limited, and any of the commonly used methods may be used, such as batch polymerization in which the entire amount of the aromatic monovinyl monomer and the entire amount of the initiator are charged into a polymerization system all at once and reacted; continuous polymerization in which they are continuously fed into a polymerization system and reacted; and a method in which polymerization is carried out using a portion of the monomer and initiator to a predetermined conversion rate, and then the remaining monomer and initiator are added to continue the polymerization. The polymerization is usually carried out at a temperature in the range of 0°C to 90°C, preferably 20°C to 80°C. When it is difficult to control the reaction temperature, it is preferable to use a reaction vessel equipped with a reflux condenser and control the temperature by reflux cooling.

[0139] Under the above conditions, an aromatic monovinyl monomer is polymerized in a solvent using an organolithium initiator to obtain a solution containing an aromatic monovinyl polymer block chain. The aromatic monovinyl polymer block chain obtained by polymerization usually has an active terminal. The aromatic monovinyl polymer block chain obtained has an active terminal. １ ) or aromatic monovinyl polymer block (Ar ３), the amount of the monomer used in this polymerization step is １ ) and aromatic monovinyl polymer block (Ar ３ ) may be determined depending on the weight average molecular weight of the copolymer.

[0140] Next, an organolithium initiator and a conjugated diene monomer are added to the solution containing the obtained aromatic vinyl polymer block chain, and polymerization is carried out. This results in a solution containing a diblock chain and a conjugated diene polymer block chain. The diblock chain and the conjugated diene polymer block chain obtained by polymerization usually have an active terminal. In addition, the obtained diblock chain has an aromatic monovinyl polymer block (Ar １ ) and aromatic monovinyl polymer block (Ar ３ ) in the polymer chain that will form a conjugated diene polymer block (D １ ) or a conjugated diene polymer block (D ３ Further, the resulting conjugated diene polymer block chain further comprises a polymer chain that forms a conjugated diene polymer block (D ２ ) and polymer C. Therefore, the amount of the monomer used in this polymerization step is １ ), conjugated diene polymer block (D ２ ), conjugated diene polymer block (D ３ ) and the weight average molecular weight of polymer C. The polymerization reaction temperature, polymerization time, and polymerization pressure may be controlled within the same ranges as those for the polymerization of the aromatic monovinyl monomer. During the polymerization of the conjugated diene monomer, the vinyl bond content in the conjugated diene monomer unit may be adjusted using the above-mentioned polar compound as a randomizer.

[0141] (Coupling Step) Next, a polyfunctional coupling agent is added to the solution containing the diblock chain and the conjugated diene polymer block chain. This causes the active terminals of the diblock chain and the conjugated diene polymer block chain to react with the polyfunctional coupling agent, resulting in three or more branched chains being bonded via the residue of the polyfunctional coupling agent, thereby forming block copolymer A1. As the polyfunctional coupling agent, those described above can be used. Alternatively, a compound that has the effect of accelerating the coupling reaction can be added.

[0142] The amount of the polyfunctional coupling agent used is adjusted to an appropriate amount depending on the number of branched chains in the block copolymer A1 and the content of the block copolymer A1 in the block copolymer composition. The amount of the polyfunctional coupling agent used is preferably within the range of 0.0001 to 20 mol, more preferably 0.01 to 10 mol, and even more preferably 0.02 to 6 mol, per mol of the organolithium initiator. By setting the amount of the polyfunctional coupling agent used within the above range, it is possible to suppress the by-production of polymer components other than the block copolymer A1, and it is possible to easily obtain the desired block copolymer composition containing the block copolymer A1.

[0143] The appropriate amount of polyfunctional coupling agent used can be calculated based on the number of branched chains in the target block copolymer A1 and the content of block copolymer A1 in the block copolymer composition. However, since deactivation of the organolithium initiator or polyfunctional coupling agent occurs in an actual polymerization reaction, it is advisable to conduct a preliminary experiment to determine the optimal value. Furthermore, if necessary, a reaction terminator such as methanol can be used to adjust the coupling rate. Furthermore, by adjusting the amount of polyfunctional coupling agent used or using a reaction terminator, the diblock chains and conjugated diene polymer block chains obtained in the polymerization step can be left unreacted and ultimately recovered as diblock copolymer B and polymer C.

[0144] The reaction temperature is preferably 10 to 150° C., more preferably 30 to 130° C., and even more preferably 40 to 90° C. The time required for the reaction varies depending on the conditions, but is usually within 48 hours, preferably 0.5 to 10 hours.

[0145] By the above method, a solution of a block copolymer composition containing the block copolymer A1 can be prepared.

[0146] (5-1-2) Method for Producing Block Copolymer Composition Containing Block Copolymer A2 Suitable examples of the method for producing a block copolymer composition containing block copolymer A2 include a production method comprising: a polymerization step of polymerizing an aromatic monovinyl monomer in a polymerization solvent using an organolithium initiator to obtain a solution containing an aromatic monovinyl polymer block chain; a polymerization step of adding a conjugated diene monomer to the solution containing the aromatic monovinyl polymer block chain and polymerizing the resulting mixture to obtain a diblock chain; and a coupling step of reacting the diblock chain with a polyfunctional coupling agent.

[0147] (Polymerization Step) The polymerization step of polymerizing an aromatic monovinyl monomer in a polymerization solvent using an organolithium initiator to obtain a solution containing an aromatic monovinyl polymer block chain can be carried out in the same manner as the corresponding polymerization step in the method for producing a block copolymer composition containing block copolymer A1, and preferred embodiments are also the same.

[0148] Specifically, an aromatic monovinyl monomer can be polymerized in a solvent using an organolithium initiator to obtain a solution containing an aromatic monovinyl polymer block chain. The aromatic monovinyl polymer block chain obtained by polymerization usually has an active terminal. The obtained aromatic monovinyl polymer block chain can be an aromatic monovinyl polymer block (Ar) or an aromatic monovinyl polymer block (Ar ３ ), the amount of the monomer used in this polymerization step is determined based on the amount of the aromatic monovinyl polymer block (Ar) and the amount of the aromatic monovinyl polymer block (Ar ３ ) may be determined depending on the weight average molecular weight of the copolymer.

[0149] Next, a conjugated diene monomer is added to the solution containing the obtained aromatic vinyl polymer block chain, and polymerization is carried out. This allows a solution containing a diblock chain to be obtained. The diblock chain obtained by polymerization usually has an active terminal. The obtained diblock chain also includes an aromatic monovinyl polymer block (Ar) and an aromatic monovinyl polymer block (Ar ３ In the polymer chain that will form the conjugated diene polymer block (D) or the conjugated diene polymer block (D ３ Therefore, the amount of the monomer used in this polymerization step is determined based on the amount of the conjugated diene polymer block (D) and the amount of the conjugated diene polymer block (D ３ The polymerization reaction temperature, polymerization time, and polymerization pressure may be controlled within the same ranges as those for the polymerization of the aromatic monovinyl monomer. In addition, the vinyl bond content in the conjugated diene monomer unit may be adjusted by using the above-mentioned polar compound as a randomizer during the polymerization of the conjugated diene monomer.

[0150] (Coupling Step) Next, a polyfunctional coupling agent is added to the solution containing the diblock chain. This causes the active terminal of the diblock chain to react with the polyfunctional coupling agent, resulting in three or more branched chains being bonded via the residue of the polyfunctional coupling agent, forming block copolymer A2. As the polyfunctional coupling agent, those described above can be used. Alternatively, a compound that promotes the coupling reaction can be added.

[0151] The amount of the polyfunctional coupling agent used is adjusted to an appropriate amount depending on the number of branched chains in block copolymer A2 and the content of block copolymer A2 in the block copolymer composition. The amount of the polyfunctional coupling agent used is preferably within the range of 0.0001 to 20 mol, more preferably 0.01 to 10 mol, and even more preferably 0.02 to 6 mol, per mol of the organolithium initiator. By using the polyfunctional coupling agent in the above range, the by-production of polymer components other than block copolymer A2 can be suppressed, and the desired block copolymer composition containing block copolymer A2 can be easily obtained.

[0152] The appropriate amount of polyfunctional coupling agent used can be calculated based on the number of branched chains in the target block copolymer A2 and the content of block copolymer A2 in the block copolymer composition. However, since deactivation of the organolithium initiator or polyfunctional coupling agent occurs in an actual polymerization reaction, it is advisable to conduct a preliminary experiment to determine the optimal value. Furthermore, if necessary, a reaction terminator such as methanol can be used to adjust the coupling rate. Furthermore, by adjusting the amount of polyfunctional coupling agent used or using a reaction terminator, the diblock chains obtained in the polymerization step can be left unreacted and ultimately recovered as diblock copolymer B.

[0153] The conditions for the coupling step can be the same as those for the coupling step in the method for producing a block copolymer composition containing the block copolymer A1, and the preferred embodiments are also the same.

[0154] By the above method, a solution of a block copolymer composition containing the block copolymer A2 can be prepared.

[0155] (5-2) Addition Step In the addition step, an alkyl radical scavenger is added to the solution of the block copolymer composition containing the block copolymer A1 or the block copolymer A2 obtained as described above. Examples of the alkyl radical scavenger include those described above as the alkyl radical scavengers contained in the pressure-sensitive adhesive composition of the present invention.

[0156] In the addition step, in addition to the alkyl radical scavenger, a polymerization terminator and an antioxidant may be added, if necessary. Examples of the polymerization terminator include water, methanol, ethanol, propanol, hydrochloric acid, and citric acid. Examples of the antioxidant include those described above as antioxidants that can be contained in the pressure-sensitive adhesive composition of the present invention.

[0157]

[0123] In the adding step, the method for adding the alkyl radical scavenger, and the polymerization terminator and antioxidant used as needed may be a conventional method, and is not particularly limited as long as the method allows the target pressure-sensitive adhesive composition to be recovered in the recovering step described below.

[0158] By the above method, a mixed solution containing the block copolymer composition, the alkyl radical scavenger, and the antioxidant used as needed can be obtained.

[0159] (5-3) Recovery Step In the recovery step, the solvent is removed from the mixed solution obtained as described above to recover a solid pressure-sensitive adhesive composition.

[0160] The method for removing the solvent from the mixed solution to recover a solid pressure-sensitive adhesive composition is not particularly limited, and examples include methods of applying known methods such as direct drying or steam stripping to the mixed solution. When steam stripping or the like is applied to the solution to recover the polymer component as a slurry, the pressure-sensitive adhesive composition in the form of crumbs can be recovered by dehydrating it using any dehydrator such as an extruder-type squeezer. The crumbs may also be dried using any dryer such as a band dryer or an expansion extrusion dryer. Furthermore, the solid pressure-sensitive adhesive composition may be processed into pellets or the like according to a conventional method, as necessary, before use.

[0161] The pressure-sensitive adhesive composition of the present invention has excellent processability, and therefore can be suitably subjected to processing that applies a strong shear stress (for example, twin-screw extrusion processing). The pressure-sensitive adhesive composition of the present invention may be obtained through processing that applies a strong shear stress (for example, twin-screw extrusion processing).

[0162] When a strong shear stress is applied to the block copolymer composition, alkyl radicals are generated as molecular chains are cleaved by the shear stress. The alkyl radicals react with the residues (X) of the polyfunctional coupling agent in the block copolymer A1 or A2 contained in the block copolymer composition. １ or X), crosslinking of the block copolymer A1 or the block copolymer A2 proceeds, resulting in a decrease in the melt index. If a block copolymer composition with a significantly decreased melt index is used, the resulting pressure-sensitive adhesive will have poor hot-melt processability.

[0163] In contrast, the pressure-sensitive adhesive composition of the present invention contains block copolymer A1 or block copolymer A2 and an alkyl radical scavenger, and therefore even when subjected to processing that applies strong shear stress (for example, twin-screw extrusion), the progress of crosslinking associated with the above reaction is suppressed, and the change in melt index before and after processing is small. Therefore, such processing can be suitably performed on the pressure-sensitive adhesive composition of the present invention. Furthermore, even when the pressure-sensitive adhesive composition after such processing is used, a pressure-sensitive adhesive with excellent hot-melt processability can be obtained. The pressure-sensitive adhesive composition of the present invention has such excellent processability and can also provide a pressure-sensitive adhesive with excellent pressure-sensitive adhesive properties.

[0164] The problem of crosslinking progression accompanying the reaction of alkyl radicals with residues of polyfunctional coupling agents is a problem specific to the use of a polyfunctional coupling agent capable of providing a block copolymer having a total of three or more branched chains. On the other hand, when a coupling agent that cannot provide a block copolymer having a total of three or more branched chains, such as dichlorodimethylsilane, is used, the above-mentioned problem of crosslinking progression does not occur.

[0165]

[0033] 6. Hot-melt adhesive composition The hot-melt adhesive composition of the present invention contains the adhesive composition of the present invention described above, a tackifying resin, and a crosslinking agent. Since the hot-melt adhesive composition of the present invention contains the adhesive composition of the present invention described above, it is possible to provide an adhesive having excellent hot-melt processability and crosslinkability, as well as excellent adhesive properties (heat resistance stability, adhesion at high temperatures, and initial adhesion).

[0166] (6-1) Tackifying Resin Conventionally known tackifying resins can be used as the tackifying resin. Specific examples of tackifying resins include rosin; modified rosins such as disproportionated rosin and dimerized rosin; esters of rosin or modified rosins with polyhydric alcohols such as glycol, glycerin, and pentaerythritol; terpene resins; aliphatic, aromatic, alicyclic, or aliphatic-aromatic copolymer hydrocarbon resins or hydrogenated versions thereof; phenolic resins; and coumarone-indene resins. The preferred tackifying resins are aliphatic or aliphatic-aromatic copolymer hydrocarbon resins that are compatible with the block copolymer composition used in the present invention. One tackifying resin may be used alone, or two or more may be used in combination.

[0167] The content of the tackifying resin in the hot melt adhesive composition is preferably in the range of 10 to 400 parts by mass, more preferably in the range of 30 to 300 parts by mass, and even more preferably in the range of 60 to 200 parts by mass, relative to 100 parts by mass of the content of the block copolymer composition in the adhesive composition contained in the hot melt adhesive composition.

[0168] (6-2) Crosslinking Agent As the crosslinking agent, known crosslinking agents used in hot melt pressure-sensitive adhesive compositions can be used. Typical crosslinking systems include peroxide crosslinking systems, sulfur crosslinking systems, and photocrosslinking systems.

[0169] The peroxide crosslinking system includes a peroxide crosslinking agent, such as t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-t-butylperoxyhexane, 2,5-dimethyl-t-butylperoxyhexyne, 1,3-bis(t-butylperoxyisopropyl)benzene, p-chlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, and t-butylbenzoate.

[0170] In addition to these peroxide-based crosslinking agents, peroxide crosslinking systems generally use polyfunctional unsaturated compounds such as toluenepropane trimethacrylate, divinylbenzene, ethylene dimethacrylate, polyethylene glycol dimethacrylate, triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diaryl itaconate, and triallyl trimellitate as a vulcanization aid.

[0171] The sulfur crosslinking system includes a sulfur-based crosslinking agent. Examples of the sulfur-based crosslinking agent include sulfur such as powdered sulfur, sulfur flowers, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur; sulfur compounds such as sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, N,N'-dithiobis(hexahydro-2H-azepinone-2), phosphorus-containing polysulfide, and polymeric polysulfides; and further, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, and 2-(4'-morpholinodithio)benzothiazole. Furthermore, in addition to these sulfur-based crosslinking agents, the sulfur crosslinking system can also use sulfur vulcanization accelerators such as stearic acid, guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, and xanthate-based.

[0172] The photocrosslinking system may be any single compound or combination of compounds that responds to light, such as ultraviolet (UV) light, to generate free radicals that initiate the polymerization of one or more monomers without excessive termination. Known photocrosslinking systems include free radical photoinitiators such as quinones, benzophenones, benzoin ethers, allyl ketones, peroxides, biimidazoles, benzil dimethyl ketals, hydroxyalkylphenyl acetophones, dialkoxyactophenones, trimethylbenzoylphosphine oxide derivatives such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, aminoketones, benzoylcyclohexanols, methylthiophenylmorpholinoketones, morpholinophenylaminoketones, alpha-halogenoacetophenones, oxysulfonylketones, sulfonylketones, benzoyloxime esters, thioxanthrones such as 2-isopropylthioxanthone, camphorquinones, ketocoumarins, and Michler's ketone, among others. Alternatively, the photocrosslinking system may be a mixture of compounds, one of which provides free radicals when induced by a radiation-activated sensitizer. The photocrosslinking system is preferably sensitive to visible or ultraviolet (actinic) radiation. The photocrosslinking system may also use the above-mentioned polyfunctional unsaturated compounds in combination with a free radical photoinitiator.

[0173] The crosslinking agent used in the present invention is not limited to the above-mentioned crosslinking agents, and may be any agent that is sensitive to active energy rays such as electron beams or radioactive rays and is capable of crosslinking the hot melt pressure-sensitive adhesive composition.

[0174] The content of the crosslinking agent in the hot melt pressure-sensitive adhesive composition is preferably in the range of 0.01 to 50 parts by mass, more preferably in the range of 0.1 to 20 parts by mass, and even more preferably in the range of 0.5 to 10 parts by mass, relative to 100 parts by mass of the content of the block copolymer composition in the pressure-sensitive adhesive composition contained in the hot melt pressure-sensitive adhesive composition.

[0175] (6-3) Plasticizer The hot melt pressure-sensitive adhesive composition of the present invention may contain a plasticizer in addition to the pressure-sensitive adhesive composition, tackifying resin, and crosslinking agent described above.

[0176] The plasticizer (softener) is not particularly limited, but an organic compound that is liquid at room temperature (23°C) is preferably used. The type of plasticizer is not particularly limited as long as it is compatible with the block copolymer composition in the pressure-sensitive adhesive composition. Specifically, aromatic, paraffinic, or naphthenic process oils; liquid polymers such as polybutene and polyisobutylene, which are added to ordinary hot-melt pressure-sensitive adhesive compositions, can be used, and among these, paraffinic process oils or naphthenic process oils are particularly preferred. Note that one type of plasticizer may be used alone, or two or more types may be used in combination.

[0177] The content of the plasticizer in the hot melt adhesive composition is preferably in the range of 0 to 200 parts by mass, more preferably in the range of 1 to 100 parts by mass, and even more preferably in the range of 2 to 50 parts by mass, relative to 100 parts by mass of the content of the block copolymer composition in the adhesive composition contained in the hot melt adhesive composition. By setting the content of the plasticizer in the above range, it is possible to further improve the hot melt processability while suppressing bleeding.

[0178] (6-4) Other Components The hot melt adhesive composition of the present invention may contain polymers other than the above-mentioned essential components. Examples of such polymers include conjugated diene homopolymers such as polybutadiene and polyisoprene, aromatic vinyl-conjugated diene random copolymers such as (styrene-butadiene) random copolymers and (styrene-isoprene) random copolymers, aromatic vinyl homopolymers such as polystyrene, isobutylene polymers, acrylic polymers, ester polymers, ether polymers, urethane polymers, and polyvinyl chloride, all of which have elasticity at room temperature (23°C), but are not limited thereto. In the hot melt adhesive composition of the present invention, the content of such polymers is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, relative to 100 parts by mass of the content of the block copolymer composition in the adhesive composition contained in the hot melt adhesive composition.

[0179] An antioxidant can be added to the hot-melt pressure-sensitive adhesive composition of the present invention, if necessary. The type of antioxidant is not particularly limited, and examples thereof include those mentioned above as antioxidants that can be contained in the pressure-sensitive adhesive composition of the present invention. One antioxidant may be used alone, or two or more antioxidants may be used in combination. When the hot-melt pressure-sensitive adhesive composition of the present invention is produced using a pressure-sensitive adhesive composition containing an antioxidant, an antioxidant of the same type as the antioxidant contained in the pressure-sensitive adhesive composition or a different type may be further added, if necessary.

[0180]

[0047] The content of the antioxidant in the hot melt pressure-sensitive adhesive composition (when a pressure-sensitive adhesive composition containing an antioxidant is used, the total content of the antioxidant in the pressure-sensitive adhesive composition and the antioxidant added later) is not particularly limited, but is preferably in the range of 10 parts by mass or less, more preferably in the range of 0.5 to 5 parts by mass, relative to 100 parts by mass of the content of the block copolymer composition in the pressure-sensitive adhesive composition contained in the hot melt pressure-sensitive adhesive composition.

[0181]

[0043] The hot melt pressure-sensitive adhesive composition of the present invention may further contain other compounding ingredients such as wax, a heat stabilizer, an ultraviolet absorber, a filler, etc. The hot melt pressure-sensitive adhesive composition of the present invention is preferably a solvent-free composition that does not contain a solvent.

[0182] (6-5) Hot-melt adhesive composition In obtaining the hot-melt adhesive composition of the present invention, the method for mixing the block copolymer composition, the tackifying resin, the crosslinking agent, and other components used as needed is not particularly limited, and examples thereof include a method in which each component is dissolved in a solvent and mixed uniformly, and then the solvent is removed by heating, or a method in which each component is melt-mixed using a kneader or the like. Of these methods, melt-mixing is preferred from the viewpoint of more efficient mixing. The temperature during melt-mixing is not particularly limited, but is usually in the range of 100 to 200°C.

[0183]

[0033] The crosslinkability of the hot melt pressure-sensitive adhesive composition of the present invention is preferably set so that after crosslinking of the hot melt pressure-sensitive adhesive composition, 50% or more of the block copolymer composition has a high molecular weight, more preferably 70% or more, and even more preferably 80% or more. By having such crosslinkability, a pressure-sensitive adhesive having even more excellent pressure-sensitive adhesive properties (heat resistance stability, adhesion at high temperatures, and initial adhesion) can be obtained.

[0184] In order to obtain appropriate crosslinkability, the crosslinkability may be appropriately adjusted by selecting the vinyl bond content in the conjugated diene monomer unit in the block copolymer composition, the type and amount of blended components such as a crosslinking agent, and the irradiation dose of active energy rays such as light to be irradiated.

[0185] When ultraviolet rays are used as the active energy rays, ultraviolet rays sources such as high-pressure mercury lamps, low-pressure mercury lamps, excimer lasers, and metal halide lamps are used, and the irradiation dose is usually 0.03 to 5 J / cm. ２ It is preferable to select the temperature within the range where the temperature is ...

[0186] 7. Pressure-sensitive adhesive The pressure-sensitive adhesive of the present invention comprises the hot-melt pressure-sensitive adhesive composition of the present invention, and is obtained by crosslinking the block copolymer A1 or the block copolymer A2 in the hot-melt pressure-sensitive adhesive composition.

[0187]

[0033] In the pressure-sensitive adhesive of the present invention, from the viewpoint of further improving the pressure-sensitive adhesive properties, it is preferable that 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more of the block copolymer composition contained in the hot-melt pressure-sensitive adhesive composition is crosslinked. In particular, the pressure-sensitive adhesive composition of the present invention has excellent hot-melt processability and can provide a pressure-sensitive adhesive having excellent pressure-sensitive adhesive properties (heat resistance stability, adhesion at high temperatures, and initial adhesion), and is also excellent in crosslinkability. Therefore, even with a relatively small amount of energy, the crosslinking ratio of the block copolymer contained in the hot-melt pressure-sensitive adhesive composition can be made relatively high as described above, and a pressure-sensitive adhesive containing many crosslinked sites can be obtained.

[0188] The applications (objects to be adhesively bonded) of the hot-melt adhesive composition and adhesive of the present invention are not particularly limited, and they can be used for various adhesive applications to which hot-melt bonding is applicable. In particular, they are particularly suitable for use as adhesives for tapes, in which the hot-melt adhesive composition is melt-coated on a film-like substrate. For example, the hot-melt adhesive composition of the present invention can be melted by heating and then melt-coated on a substrate. Before the hot-melt adhesive composition completely solidifies, an adherend made of the same or a different material as the substrate can be pressed and bonded. In this case, the hot-melt adhesive composition can also be crosslinked to form an adhesive. The hot-melt adhesive composition of the present invention has excellent hot-melt processability, contributing to a reduction in the reject rate and an improvement in productivity in the production of such tapes. Furthermore, the resulting tapes have excellent adhesive properties (heat resistance stability, adhesion at high temperatures, and initial adhesion).

[0113] The hot melt pressure-sensitive adhesive composition and pressure-sensitive adhesive of the present invention can also be suitably used for hygiene products such as disposable paper diapers and sanitary napkins; food packaging such as frozen foods, fresh foods, and confectioneries; packaging of components such as automobile parts and machine parts; packaging of electrical products such as televisions, audio products, and refrigerators; bookbinding applications such as slips, books, and catalogs; bag making applications such as kraft bags, polypropylene bags, and polyethylene bags; clothing applications such as hemming coats, bonding leather and fabrics, and bonding interlinings; and the like.

[0189] The hot melt adhesive composition and adhesive of the present invention can also be applied to the production of labels. The label preferably comprises a support and an adhesive layer comprising the hot melt adhesive composition or adhesive of the present invention. The adhesive layer can usually be formed by applying the hot melt adhesive composition of the present invention to a support, drying it, and then crosslinking it as necessary.

[0190] The support to be used is not particularly limited and examples thereof include papers such as kraft paper, Japanese paper, fine paper, and synthetic paper; fabrics such as cotton cloth, staple fiber cloth, and polyester cloth; resin films such as cellophane film, polyvinyl chloride film, polypropylene film, and polyethylene film; metal foils such as aluminum foil and copper foil; nonwoven fabrics such as polyester nonwoven fabric and rayon nonwoven fabric, etc. The surface of these supports may be previously subjected to a corona discharge treatment or coated with a primary coating agent.

[0191] A label obtained using the hot melt pressure-sensitive adhesive composition or pressure-sensitive adhesive of the present invention may be cut, punched, or otherwise processed into an appropriate shape depending on its intended use. Furthermore, the pressure-sensitive adhesive layer of a label using the hot melt pressure-sensitive adhesive composition or pressure-sensitive adhesive of the present invention is not limited to being continuously formed. For example, the pressure-sensitive adhesive layer may be formed in a regular or random pattern, such as a dotted or striped pattern.

[0192] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and that provides similar effects is included within the technical scope of the present invention.

[0193] The present invention will be described in more detail below with reference to examples and comparative examples. In each example, parts and percentages are by weight unless otherwise specified.

[0194] Various measurements were carried out according to the following methods.

[0195] [Weight-average molecular weight and molecular weight distribution] The weight-average molecular weight was determined as polystyrene equivalent molecular weight by high-performance liquid chromatography using tetrahydrofuran as a carrier at a flow rate of 0.35 ml / min. The apparatus used was a Tosoh HLC8320, the column consisted of three connected Shodex (registered trademark) KF-404HQ columns manufactured by Showa Denko K.K. (column temperature: 40°C), and the detectors were a differential refractometer and an ultraviolet detector. The molecular weight was calibrated at 12 points using standard polystyrenes (5 to 3 million) manufactured by Polymer Laboratory.

[0196] [Content of Each Polymer in Block Copolymer Composition] The content of each polymer in the block copolymer composition was determined from the area ratio of the peaks corresponding to each polymer (block copolymer A1, block copolymer A2, diblock copolymer B, polymer C) in the chart obtained by the above-mentioned high performance liquid chromatography.

[0197] [Weight-Average Molecular Weight of Styrene Polymer Block of Block Copolymer] According to the method described in Rubber Chem. Technol., 45, 1295 (1972), the block copolymer was reacted with ozone and reduced with lithium aluminum hydride to decompose the isoprene polymer block of the block copolymer. Specifically, the following procedure was performed. 300 mg of sample was dissolved in a reaction vessel containing 100 ml of dichloromethane treated with molecular sieves. The reaction vessel was placed in a cooling bath and cooled to -25°C. Ozone generated by an ozone generator was then introduced into the reaction vessel while oxygen was flowing into the reaction vessel at a flow rate of 170 ml / min. Thirty minutes after the start of the reaction, the completion of the reaction was confirmed by introducing the gas flowing out of the reaction vessel into an aqueous potassium iodide solution. Next, 50 ml of diethyl ether and 470 mg of lithium aluminum hydride were placed in a nitrogen-purged reaction vessel. While cooling the reaction vessel with ice water, the solution reacted with ozone was slowly added dropwise to the reaction vessel. The reaction vessel was then placed in a water bath, gradually heated, and refluxed at 40°C for 30 minutes. Dilute hydrochloric acid was then added dropwise to the reaction vessel while stirring the solution, and the addition was continued until hydrogen generation was almost completely eliminated. After the reaction, the solid product formed in the solution was filtered and extracted with 100 ml of diethyl ether for 10 minutes. This extract and the filtrate were combined, and the solvent was distilled off to obtain a solid sample. The weight-average molecular weight of the sample thus obtained was measured according to the above-described method for measuring weight-average molecular weight, and the resulting value was taken as the weight-average molecular weight of the styrene polymer block.

[0198] [Weight-Average Molecular Weight of Isoprene Polymer Block of Block Copolymer] The weight-average molecular weight of the corresponding styrene polymer block was subtracted from the weight-average molecular weight of the block copolymer determined as described above, and the weight-average molecular weight of the isoprene polymer block was determined based on the calculated value.

[0199] [The mass ratio of the branched chains in the block copolymer A1 ((Ar １ -D １ ) / D ２ ) 2 mL of the polymer solution before the coupling step was sampled and mixed with 1 mL of excess methanol to inactivate the polymerization activity. This sample was analyzed by high performance liquid chromatography, and the mass ratio of the branched chains in the block copolymer A1 ((Ar １ -D １ ) / D ２ ) was sought.

[0200] [The ratio of the weight average molecular weight of the isoprene polymer block in the block copolymer A1 ((Mw(D １ )) / (Mw(D ２ In the same manner as above, the sample collected before the coupling step was analyzed by high performance liquid chromatography to determine the presence of Ar １ -D １ and D ２ After determining the weight average molecular weight of the styrene polymer block of block copolymer A1 determined by the above method, the weight average molecular weight ratio of the isoprene polymer block in block copolymer A1 ((Mw(D １ )) / (Mw(D ２ ))) was asked.

[0201] [Average Branch Number of Block Copolymer A1] The weight average molecular weight of block copolymer A1, Ar １ -D １ and D ２ and the weight average molecular weight of the branched chain in the block copolymer A1 ((Ar １ -D １ ) / D ２ ) The average branch number of the block copolymer A1 was calculated.

[0202] [Average Branch Number of Block Copolymer A2] In the same manner as described above, a sample collected before the coupling step was analyzed by high performance liquid chromatography to determine the weight average molecular weight of Ar-D. Then, the average branch number of block copolymer A2 was calculated from the weight average molecular weight of block copolymer A2 determined by the above method and the weight average molecular weight of Ar-D.

[0203] [Content of Styrene Units in the Whole Block Copolymer Composition] The styrene unit content was determined based on proton NMR measurement.

[0204] [Type A Hardness of Block Copolymer Composition] The type A hardness was measured using a durometer hardness tester (type A) in accordance with JIS K6253.

[0205] [Melt index of pressure-sensitive adhesive composition before and after twin-screw extrusion] The melt index of the crumb-like pressure-sensitive adhesive composition before twin-screw extrusion and the pellet-like pressure-sensitive adhesive composition after twin-screw extrusion was measured in accordance with ASTM D1238 (G condition, 200°C, 5 kg load). The smaller the change in melt index before and after twin-screw extrusion, the more excellent the processability of the pressure-sensitive adhesive composition can be determined.

[0206] [Hot melt processability] 10 g of the hot melt pressure-sensitive adhesive composition was sampled, and the melt viscosity (unit: mPa s) at 180°C was measured with a Thermocell-type Brookfield viscometer using a rotor No. 27. When the melt viscosity value was 500,000 mPa s or less, the hot melt processability was excellent and the pressure-sensitive adhesive was easy to manufacture by hot melt, and the composition was evaluated as "A". On the other hand, when the melt viscosity value exceeded 500,000 mPa s, the hot melt processability was poor and the composition was evaluated as "B".

[0207] [Adhesive Residue Test] The hot-melt pressure-sensitive adhesive composition was melt-coated onto a 25 μm-thick PET film to a thickness of 20 to 30 μm to obtain a coated sheet. This coated sheet was then cut to obtain a pre-crosslinked test piece. The pre-crosslinked test piece thus obtained was attached to a stainless steel plate by pressing with a 2 kg rubber roller at a speed of 300 mm / min under conditions of 23°C, and the specimen left at 100°C for 12 hours after attachment was used as a measurement sample. This measurement sample was subjected to a peel test at 23°C at a peel speed of 15 m / min using a high-speed peel tester "TE-701-S" manufactured by Tester Sangyo Co., Ltd. in accordance with PSTC-1 (180° Peel Adhesion Test by the US Adhesive Tape Committee) to determine the peel adhesion strength (N / m). The heat resistance stability of the pre-crosslinked hot-melt pressure-sensitive adhesive composition was evaluated by visually checking for adhesive residue on the stainless steel plate after peeling.

[0208] In addition, the test piece before crosslinking was subjected to 100 mJ / cm under a UV-C lamp. ２ The hot melt adhesive composition was crosslinked by irradiating ultraviolet light under the conditions of (a) to (b) to obtain a test piece having an adhesive layer. Using the obtained test piece, the peel strength (N / m) of the adhesive after crosslinking was determined and the heat resistance stability was evaluated. Specifically, a test piece in which no adhesive residue was visible was evaluated as "A", a test piece in which adhesive residue was visible in part was evaluated as "B", and a test piece in which adhesive residue was visible over the entire surface was evaluated as "C". It can be determined that the less adhesive residue there was, the more excellent the heat resistance stability.

[0209] [SAFT] A hot melt pressure-sensitive adhesive composition was melt-coated onto a 25 μm thick PET film to a thickness of 20 to 30 μm to obtain a coated sheet. This coated sheet was then cut to obtain a pre-crosslinked test piece. The pre-crosslinked test piece thus obtained was brought into contact with a stainless steel substrate so that the adhesive area was 10 × 25 mm, and pressure-bonded at a rate of 300 mm / min using a 2 kg rubber roller at 23°C to obtain a measurement sample. The shear failure temperature (SAFT) of the pre-crosslinked hot melt pressure-sensitive adhesive composition was measured for this measurement sample at a temperature increase rate of 0.5°C / min under a load of 500 g.

[0210] In addition, the test piece before crosslinking was subjected to 100 mJ / cm under a UV-C lamp. ２ The hot melt pressure-sensitive adhesive composition was crosslinked by irradiating ultraviolet light under the conditions of (a) to (c) to obtain a test piece having a pressure-sensitive adhesive layer. The shear failure temperature (SAFT) of the pressure-sensitive adhesive after crosslinking was measured using the obtained test piece. It can be determined that the higher the shear failure temperature (SAFT), the more excellent the high temperature adhesive performance (adhesion at high temperatures).

[0211] [Loop Tack] A hot melt pressure-sensitive adhesive composition was melt-coated onto a 25 μm PET film to a thickness of 20 to 30 μm to obtain a coated sheet. Next, this coated sheet was cut to obtain a pre-crosslinking test piece. Using the thus obtained pre-crosslinking test piece, the loop tack (N / 25 mm) of the pre-crosslinking hot melt pressure-sensitive adhesive composition was evaluated with a tensile tester at a test speed of 300 mm / min, a bonded area of ​​25 × 25 mm, and a temperature of 23°C, using a stainless steel plate as the adherend.

[0212] In addition, the test piece before crosslinking was subjected to 100 mJ / cm under a UV-C lamp. ２ The hot melt adhesive composition was irradiated with ultraviolet light under the conditions of (a) to (b) to crosslink the hot melt adhesive composition, thereby obtaining a test piece having an adhesive layer. Using the obtained test piece, the loop tack of the adhesive after crosslinking was evaluated. The larger the value, the better the initial adhesion.

[0213] [Crosslinkability] The hot melt adhesive composition was crosslinked under a UV-C lamp at 100 mJ / cm ２The hot-melt adhesive composition was crosslinked by irradiating light under the conditions of

[0049] to obtain a pressure-sensitive adhesive. Next, the hot-melt adhesive composition before crosslinking and the pressure-sensitive adhesive after crosslinking were measured by high performance liquid chromatography to evaluate crosslinkability. Specifically, when the molecular weight of block copolymer A1 or block copolymer A2 before crosslinking is increased by crosslinking, the peak area derived from block copolymer A1 or block copolymer A2 decreases. Utilizing this, the percentage decrease in the peak area derived from block copolymer A1 or block copolymer A2 before and after crosslinking was determined based on the peak area derived from block copolymer A1 or block copolymer A2 contained in the hot-melt adhesive composition before crosslinking. In the table, ">90(%)" means that the percentage decrease in peak area exceeded 90%. The greater the percentage decrease in peak area, the better the crosslinkability can be determined.

[0214] [Production Example 1] A 2-liter pressure-resistant reactor was used, and 400 g of a mixed solvent of n-butane / cyclohexane (30 / 70), 0.07 mmol of tetramethylethylenediamine, and 2.25 mmol of n-butyllithium initiator were added to the mixture. 22 g of styrene was added and polymerized at 30°C for 1 hour. 78 g of isoprene was then added, and polymerization was continued for approximately 1.5 hours while controlling the reaction temperature by reflux cooling so that the reaction temperature was between 50°C and 60°C. Next, divinylbenzene (DVB) was added as a coupling agent in an amount of 4 times the equivalent of the total n-butyllithium, and a coupling reaction was carried out for 2 hours. After this, 1 ml of methanol was added to the reaction mixture as a polymerization terminator, yielding a solution containing block copolymer composition (1). Using the resulting solution, the block copolymer composition (1) in the solution was measured as described above. The results are shown in Table 1.

[0215] [Production Example 2] Using a 2-liter pressure-resistant reactor, 400 g of a mixed solvent of n-butane / cyclohexane (30 / 70), 0.07 mmol of tetramethylethylenediamine, and 1.75 mmol of initiator n-butyllithium were added to 22 g of styrene, and polymerization was carried out at 30°C for 1 hour. Subsequently, 0.75 mmol of n-butyllithium and 78 g of isoprene were added, and polymerization was carried out for approximately 1.5 hours while controlling the reaction temperature by reflux cooling so that the reaction temperature was between 50°C and 60°C. Next, divinylbenzene (DVB) was added as a coupling agent in an amount of 4 times the equivalent of the total n-butyllithium, and a coupling reaction was carried out for 2 hours. After this, 1 ml of methanol was added as a polymerization terminator to the reaction mixture to obtain a solution containing block copolymer composition (2). Using the resulting solution, the block copolymer composition (2) in the solution was measured as described above. The results are shown in Table 1.

[0216] [Production Example 3] Using a 2-liter pressure-resistant reactor, 400 g of a mixed solvent of n-butane / cyclohexane (30 / 70), 0.07 mmol of tetramethylethylenediamine, and 2 mmol of n-butyllithium initiator were added to 25 g of styrene, and polymerization was carried out at 30°C for 1 hour. Subsequently, 75 g of isoprene was added, and polymerization was carried out for approximately 1.5 hours while controlling the temperature by reflux cooling so that the reaction temperature was between 50°C and 60°C. Next, dichlorodimethylsilane (DMDCS) was added as a coupling agent in an amount of 0.375 equivalents relative to the total amount of n-butyllithium, and a coupling reaction was carried out for 2 hours. Thereafter, 1 ml of methanol was added as a polymerization terminator to the reaction mixture to obtain a solution containing block copolymer composition (3). Using the obtained solution, the block copolymer composition (3) in the solution was measured as described above. The results are shown in Table 1.

[0217]

[0218] In the examples and comparative examples, the following alkyl radical scavengers and antioxidants were used. [Hindered phenol-based antioxidants] Irganox 1010: Pentaerythritol tetrakis[3-[3,5-di(tert-butyl)-4-hydroxyphenyl]propionate], manufactured by BASF Irganox 565: 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol, manufactured by BASF [Phosphorus-based antioxidants] Irgafos 168: Tris(2,4-di-tert-butylphenyl) phosphite, manufactured by BASF [Alkyl radical scavengers] Sumilizer GM: 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, manufactured by Sumitomo Chemical Co., Ltd. Sumilizer GS: 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate, manufactured by Sumitomo Chemical Co., Ltd.

[0219] Example 1-1 To a solution containing the block copolymer composition (1) obtained in Production Example 1, 0.1 parts of Irganox 1010, 0.2 parts of Irgafos 168, and 0.2 parts of Sumilizer GM were added, in amounts relative to 100 parts of the block copolymer composition (1), and mixed well. The resulting mixed solution was added dropwise in small amounts to warm water heated to 85 to 95°C to volatilize the solvent, and a crumb-like pressure-sensitive adhesive composition was recovered. The resulting crumb-like pressure-sensitive adhesive composition was charged into a twin-screw kneading extruder and subjected to twin-screw extrusion processing, thereby obtaining a pellet-like pressure-sensitive adhesive composition. The configuration of the twin-screw kneading extruder used and the twin-screw extrusion processing conditions are shown below.

[0220] [Configuration of twin-screw kneading extruder] Co-rotating twin-screw kneading extruder HK-25D (41D) (manufactured by Parker Corporation) φ25 mm, L / D=41, number of barrels=7 [Twin-screw kneading extrusion conditions] Barrel set temperature: 180°C Resin temperature: 210°C Rotation speed (rpm): 100 Feeding rate (gravimetric feeder used): 5 kg / h

[0221] The melt index of the crumb-like pressure-sensitive adhesive composition before the twin-screw extrusion processing and the pellet-like pressure-sensitive adhesive composition after the twin-screw extrusion processing was measured in the same manner as described above. The results are shown in Table 2.

[0222] Examples 1-2 to 1-6, Comparative Examples 1-1 to 1-6 Crumb-like pressure-sensitive adhesive compositions and pellet-like pressure-sensitive adhesive compositions were obtained in the same manner as in Example 1-1, except that the solution obtained in any one of Production Examples 1 to 3 shown in Table 2 was used as the solution containing the block copolymer composition, and that Irganox 1010, Irganox 565, Irgafos 168, Sumilizer GM and Sumilizer GS were used in the amounts shown in Table 2 relative to 100 parts of the block copolymer composition. Measurements were carried out in the same manner as in Example 1-1 using the obtained pressure-sensitive adhesive compositions. The results are shown in Table 2.

[0223]

[0224] Example 2-1 The pellet-shaped pressure-sensitive adhesive composition obtained in Example 1-1 was charged into an agitator blade type kneader, and to this was added 100 parts of a petroleum resin (aliphatic-aromatic copolymer hydrocarbon resin, trade name "Quinton S195", manufactured by Zeon Corporation), 10 parts of a naphthenic process oil (trade name "SUNPURE N100", manufactured by Nippon Sun Oil Co., Ltd.) as a softener (plasticizer), 1 part of crosslinking agent 1 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, Omnirad 819, manufactured by IGM ResinS), 1 part of crosslinking agent 2 (2-isopropylthioxanthone, 2-ITX, manufactured by IGM ResinS), and Irganox 1010, in amounts relative to 100 parts of the block copolymer composition (1) in the pressure-sensitive adhesive composition. After adding 1 part of the above and replacing the atmosphere in the system with nitrogen gas, the mixture was kneaded at 160°C for 1.5 hours to prepare a hot melt adhesive composition.

[0225] The hot melt pressure-sensitive adhesive compositions thus obtained were evaluated for hot melt processability, adhesive residue test, SAFT, loop tack and crosslinkability. The results are shown in Table 3.

[0226] [Examples 2-2 to 2-6, Comparative Examples 2-1 to 2-6] Hot-melt pressure-sensitive adhesive compositions were obtained in the same manner as in Example 2-1, except that the pressure-sensitive adhesive compositions obtained in the Examples or Comparative Examples shown in Table 3 were used instead of the pressure-sensitive adhesive composition obtained in Example 1-1. Measurements were carried out in the same manner as in Example 2-1 using the obtained hot-melt pressure-sensitive adhesive compositions. The results are shown in Table 3.

[0227]

[0228]

[0047] As shown in Table 3, the pressure-sensitive adhesive compositions containing a block copolymer composition comprising a block copolymer A1 represented by the general formula (1) or a block copolymer A2 represented by the general formula (2) and an alkyl radical scavenger, wherein the weight average molecular weight (Mw) of the whole block copolymer composition was 300,000 to 800,000 and the content of the alkyl radical scavenger was 0.05 to 2 parts by mass per 100 parts by mass of the content of the block copolymer composition, were capable of providing pressure-sensitive adhesives having excellent processability and excellent pressure-sensitive adhesive properties (Examples 1-1 to 1-6 and Examples 2-1 to 2-6).

[0229] On the other hand, when the block copolymer composition containing the block copolymer A1 or the block copolymer A2 was contained but no alkyl radical scavenger was contained, the change in melt index before twin-screw extrusion processing was large, and the hot-melt processability of the obtained hot-melt pressure-sensitive adhesive composition was poor, resulting in poor processability (Comparative Examples 1-1, 1-2, 1-4 and Comparative Examples 2-1, 2-2, 2-4).

[0230] Moreover, when the content of the alkyl radical scavenger was too high, the resulting adhesive had poor adhesive properties (Comparative Examples 1-3 and 2-3).

[0231] Furthermore, when the block copolymer composition containing the block copolymer A1 or the block copolymer A2 was not contained, the melt index before the twin-screw extrusion processing hardly changed, regardless of the presence or absence of an alkyl radical scavenger, but the adhesive properties of the obtained pressure-sensitive adhesive were inferior (Comparative Examples 1-5, 1-6 and Comparative Examples 2-5, 2-6).

Claims

1. A block copolymer composition comprising a block copolymer A1 represented by the following general formula (1) or a block copolymer A2 represented by the following general formula (2), and an alkyl radical scavenger, wherein the adhesive composition comprises The weight-average molecular weight (Mw) of the entire block copolymer composition is 300,000 to 800,000. A composition for adhesives in which the amount of the alkyl radical scavenger is 0.05 to 2 parts by mass per 100 parts by mass of the block copolymer composition. (Ar １ -D １ ) ｍ X １ (D ２ ) ｎ (1) (In general formula (1), Ar １ is an aromatic monovinyl polymer block, D １ and D ２ are each a conjugated diene polymer block, m is an integer of 1 or more, n is an integer of 1 or more, m + n is an integer of 3 or more, and X １ is a residue of a polyfunctional coupling agent.) (Ar-D) ｐ X (2) (In general formula (2), Ar is an aromatic monovinyl polymer block, D is a conjugated diene polymer block, p is an integer of 3 or more, and X is a residue of a polyfunctional coupling agent.)

2. The molecular weight distribution (Mw / Mn) of the block copolymer A1 or the block copolymer A2 is 1.40 or less. The adhesive composition according to claim 1, wherein the total content of the block copolymer A1 and the block copolymer A2 in the block copolymer composition is 10% by mass or more.

3. The block copolymer composition further comprises a diblock copolymer B represented by the following general formula (3) or a polymer C represented by the following general formula (4), The molecular weight distribution (Mw / Mn) of the diblock copolymer B or the polymer C is 1.20 or less. The total content of the diblock copolymer B and the polymer C in the block copolymer composition is 60% by mass or less. The content of aromatic monovinyl monomer units in the block copolymer composition is 5 to 40% by mass. The adhesive composition according to claim 1 or 2, wherein the block copolymer composition has a Type A hardness of 25 to 65 as measured using a durometer hardness tester (Type A) in accordance with JIS K6253. Ar ３ -D ３ (3) D ４ (4) (In general formulas (3) and (4), Ar ３ This is an aromatic monovinyl polymer block, D ３ and D ４ These are each conjugated diene polymer blocks.

4. The adhesive composition according to claim 1 or 2, wherein the melt index measured in accordance with ASTM D1238 (G conditions, 200°C, 5 kg load) is 1.5 to 50 g / 10 min.

5. The block copolymer composition comprises the block copolymer A1, In the block copolymer A1, D ２ For the mass of the branched chain represented by Ar １ -D １ The ratio of the masses of branched chains represented by (Ar １ -D １ ) / D ２ The adhesive composition according to claim 1 or 2, wherein the ratio is 1.0 / 0.15 to 1.0 / 1.

75.

6. The block copolymer composition contains the block copolymer A1, In the block copolymer A1, D ２ The weight-average molecular weight (Mw(D)) of a branched chain is represented by ２ )) vs. Ar １ -D １ Conjugated diene polymer block D in a branched chain, represented by １ Weight-average molecular weight (Mw(D) １ )) ratio ((Mw(D １ )) / (Mw(D ２ The adhesive composition according to claim 1 or 2, wherein the ratio is 1.0 / 0.3 to 1.0 / 1.

1.

7. The adhesive composition according to claim 1 or 2, wherein the polyfunctional coupling agent is a compound having two or more radical polymerizable groups in its molecule.

8. The adhesive composition according to claim 7, wherein the polyfunctional coupling agent is divinylbenzene.

9. The adhesive composition according to claim 1 or 2, wherein the conjugated diene polymer block is an isoprene polymer block.

10. The adhesive composition according to claim 1 or 2, wherein the alkyl radical scavenger is at least one selected from 2-[1-(2-hydroxy-3,5-di-t-pentylphenyl)ethyl]-4,6-di-t-pentylphenyl acrylate and 2-t-butyl-6-(3-t-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate.

11. It further contains at least one antioxidant selected from hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, and benzofuranone antioxidants. The adhesive composition according to claim 1 or 2, wherein the content of the antioxidant is 0.01 to 10 parts by mass per 100 parts by mass of the block copolymer composition.

12. A hot melt adhesive composition comprising the adhesive composition according to claim 1 or 2, a tackifying resin, and a crosslinking agent, A hot melt adhesive composition wherein the content of the tackifying resin is 10 to 400 parts by mass per 100 parts by mass of the block copolymer composition in the adhesive composition, and the content of the crosslinking agent is 0.01 to 50 parts by mass.

13. The hot melt adhesive composition according to claim 12, wherein the plasticizer is contained in an amount of 0 to 200 parts by mass per 100 parts by mass of the block copolymer composition in the adhesive composition.

14. A viscous adhesive comprising the hot melt viscous adhesive composition described in claim 12, A viscous adhesive obtained by crosslinking the block copolymer A1 or the block copolymer A2 in the hot melt viscous adhesive composition.