JP7451938B2 - Adhesive compositions and adhesive products - Google Patents

Description

The present invention relates to an adhesive composition and an adhesive product, and more particularly to an adhesive composition and an adhesive product containing a (meth)acrylic adhesive polymer.

Acrylic pressure-sensitive adhesives are used in a wide range of applications because they have advantages such as excellent weather resistance and transparency, and a high degree of freedom in design. In addition, various materials such as plastic, paper, metal, wood, glass, fiber fabric, etc. are applied to the objects to which acrylic adhesives are applied (for example, see Patent Document 1 and Patent Document 2). .

Patent Document 1 discloses that a thermal adhesive tape partially coated with an adhesive material such as acrylic resin is inserted between fiber fabrics, and the fabrics are bonded together by heat fusing. has been done. Further, Patent Document 2 describes a fiber fabric containing a vinyl polymer having a glass transition point of 30°C or more and 200°C or less and a number average molecular weight of 500 or more and 10,000 or less, and an acrylic adhesive polymer. A pressure-sensitive adhesive composition for bonding is disclosed.

Japanese Patent Application Publication No. 2002-338908 JP 2019-11382 Publication

In the case of the method of joining fabrics together using a thermal adhesive tape described in Patent Document 1, the adhesive strength is not sufficient, and there is a risk that the bonded area may peel off if tensile stress is applied to the bonded area or if it is used repeatedly. .

It is also assumed that articles manufactured using acrylic adhesives will be used in high-temperature environments. For example, clothing manufactured by bonding fiber fabrics together using an acrylic adhesive may be exposed to a high temperature environment of about 80° C. by using a dryer or washing with hot water. However, the cohesive force of acrylic pressure-sensitive adhesives tends to decrease in high-temperature environments, and there is a concern that the adhesive portion may peel off when used in high-temperature environments. In addition, so-called unsewn clothing, in which fiber fabrics are bonded together using an adhesive rather than sewn together using a sewing machine, has high peel strength under high temperature conditions, as well as high peel strength under room temperature conditions. It is required to be resistant to peeling even under tensile stress and repeated use.

The present invention has been made in view of the above problems, and its main purpose is to provide a pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive layer with high peel strength under high temperature conditions and room temperature conditions.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by creating an adhesive composition containing a (meth)acrylic adhesive polymer having a specific structure. The present invention was completed based on these findings. According to the present invention, the following means are provided.

[1] A polymer block A having a glass transition point of 50° C. or higher, and a polymer block B having a glass transition point of 10° C. or lower and mainly consisting of structural units derived from a (meth)acrylic monomer. and a multi-block copolymer in which the total number of the polymer block A and the polymer block B in one molecule is 4 or more.

[2] The multi-block copolymer according to [1], wherein the ratio of the polymer block A to the total amount of the polymer block A and the polymer block B is 5 mol% or more and 40 mol% or less. Adhesive composition.
[3] The adhesive composition of [1] or [2], wherein the multi-block copolymer has three or more of the polymer blocks A in one molecule.
[4] The multi-block copolymer is a polymer having, as the polymer block A, at least one selected from the group consisting of a structural unit derived from a styrene compound and a structural unit derived from an imide group-containing vinyl compound. The adhesive composition according to any one of [1] to [3], which contains a block.

[5] The multi-block copolymer includes, as the polymer block A, a first polymer block and a second polymer block having a different composition of constituent monomer units from the first polymer block. The pressure-sensitive adhesive composition according to any one of [1] to [4], comprising:
[6] The first polymer block is a polymer block having a structural unit derived from a styrene compound, and the second polymer block is a polymer block having a structural unit derived from a (meth)acrylic monomer. The pressure-sensitive adhesive composition of [5], which is a polymer block having the following.
[7] The adhesive composition of [5] or [6], wherein the first polymer block and the second polymer block have a structural unit derived from an imide group-containing vinyl compound.

[8] The polymer block B has a structural unit derived from at least one selected from the group consisting of an alkyl (meth)acrylate compound and an alkoxyalkyl (meth)acrylate compound, [1] to [7] Any one of the adhesive compositions.
[9] The adhesive composition according to any one of [1] to [7], wherein the polymer block B has a structural unit derived from a hydroxyalkyl (meth)acrylate compound.
[10] Any one of [1] to [9], wherein the multi-block copolymer is a pentablock copolymer in which the total number of the polymer blocks A and the polymer blocks B is 5. adhesive composition.
[11] An adhesive product comprising a support and an adhesive layer formed on the support using the adhesive composition of any one of [1] to [10] above.

According to the adhesive composition of the present invention, it is possible to obtain an adhesive layer that exhibits high peel strength both under high temperature conditions and under room temperature conditions.

The present disclosure will be described in detail below. In addition, in this specification, "(meth)acrylic" means acrylic and/or methacryl, and "(meth)acrylate" means acrylate and/or methacrylate. Moreover, "(meth)acryloyl group" means an acryloyl group and/or a methacryloyl group.

《Adhesive composition》
The adhesive composition of the present invention is a multi-block copolymer (hereinafter also referred to as "multi-block copolymer (P)") having a polymer block A as a hard segment and a polymer block B as a soft segment. ). Below, the multi-block copolymer (P) blended into the present adhesive composition and the components blended as needed will be explained in detail.

<Multi-block copolymer (P)>
The multi-block copolymer (P) has a total of four or more polymer blocks A and polymer blocks B. The multi-block copolymer (P) is a copolymer that can form pseudo-crosslinks by forming a microphase separation structure or the like. When the copolymer forms a pseudo-crosslinked structure in the pressure-sensitive adhesive layer, the cohesive force tends to improve, which is preferable since the adhesive strength can be increased.

(Polymer block A)
Polymer block A is a polymer block having a glass transition point of 50°C or higher. The multi-block copolymer (P) has good heat resistance and durability because the glass transition point (hereinafter also referred to as "glass transition point TgA") of the polymer block A is 50 ° C. or higher. be able to. The multi-block copolymer (P) preferably has a plurality of polymer blocks A in one molecule. When the multi-block copolymer (P) has a plurality of polymer blocks A in one molecule, the structures of each block of the plurality of polymer blocks A may be the same or different from each other.

Examples of the monomers constituting the polymer block A include styrene compounds, imide group-containing vinyl compounds, (meth)acrylic monomers, and the like.

Styrene compounds include styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, vinylxylene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, -Ethylstyrene, p-n-butylstyrene, p-isobutylstyrene, pt-butylstyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, p-chloromethylstyrene, p-chlorostyrene, divinyl Examples include benzene. As the styrene compound, one or more of these can be used.

When the polymer block A has a structural unit derived from a styrene compound, the content of the structural unit derived from the styrene compound is preferably 5 mol% or more with respect to all constituent monomer units of the polymer block A. It is more preferably 10 mol% or more, still more preferably 20 mol% or more. Further, the upper limit of the content of the structural unit derived from the styrene compound with respect to all the constituent monomer units of the polymer block A is not particularly limited, and can be set at 100 mol% or less. The upper limit of the content of structural units derived from styrene compounds is preferably 95 mol% or less, more preferably 90 mol% or less, based on all constituent monomer units of polymer block A, and Preferably it is 80 mol% or less.

Examples of imide group-containing vinyl compounds include maleimide compounds such as maleimide and N-substituted maleimide compounds; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, and N-2-ethylhexylitacone. imide, N-cyclohexyl citraconimide, N-lauryl citraconimide, and other itaconimide compounds; N-methyl citraconimide, N-ethyl citraconimide, N-butyl citraconimide, N-octyl citraconimide, N-2-ethylhexyl citraconimide, Citraconimide compounds such as N-cyclohexylcitraconimide and N-laurylcitraconimide; N-(2-(meth)acryloyloxyethyl)succinimide, N-(2-(meth)acryloyloxyethyl)maleimide, N-( 2-(meth)acryloyloxyethyl)phthalimide, N-(4-(meth)acryloyloxybutyl)succinimide, N-(4-(meth)acryloyloxybutyl)maleimide, N-(4-(meth)acryloyloxybutyl)maleimide, ) Acryloyloxybutyl) phthalic acid imide and other (meth)acrylimide compounds. As the imide group-containing vinyl compound, a maleimide compound can be suitably used.

（式（１）中、Ｒ^１は水素原子、炭素数１～３のアルキル基、シクロヘキシル基、フェニル基、又は、フェニル基の任意の位置にヒドロキシ基、炭素数１～２のアルコキシ基、アセチル基又はハロゲン原子が結合した置換フェニル基を表す。） Maleimide compounds include maleimide and N-substituted maleimide compounds. Examples of N-substituted maleimide compounds include N-methylmaleimide, N-ethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn-butylmaleimide, N-isobutylmaleimide, N-tert-butylmaleimide, N- - N-alkyl substituted maleimide compounds such as pentylmaleimide, N-hexylmaleimide, N-heptylmaleimide, N-octylmaleimide, N-laurylmaleimide, N-stearylmaleimide; N- such as N-cyclopentylmaleimide, N-cyclohexylmaleimide, etc. Cycloalkyl-substituted maleimide compounds; N-aralkyl-substituted maleimide compounds such as N-benzylmaleimide; N-phenylmaleimide, N-(4-hydroxyphenyl)maleimide, N-(4-acetylphenyl)maleimide, N-(4-methoxy Examples include N-aryl-substituted maleimide compounds such as phenyl)maleimide, N-(4-ethoxyphenyl)maleimide, N-(4-chlorophenyl)maleimide, and N-(4-bromophenyl)maleimide. Among the above, the maleimide compound used in the production of the polymer block A is a maleimide compound represented by the following formula (1) in that it can improve the heat resistance and adhesiveness of the multi-block copolymer (P). The compounds represented are preferred.

(In formula (1), R ¹ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a phenyl group, or a hydroxy group, an alkoxy group having 1 to 2 carbon atoms, an acetyl group at any position of the phenyl group) or a substituted phenyl group to which a halogen atom is bonded.)

The content of the structural unit derived from the imide group-containing vinyl compound can be appropriately set within a range of 100 mol % or less based on all the constituent monomer units of the polymer block A. When the polymer block A contains a structural unit derived from an imide group-containing vinyl compound, it is preferable in that a multi-block copolymer (P) having excellent heat resistance and adhesiveness can be obtained. The content of the structural unit derived from the imide group-containing vinyl compound is preferably 5 mol% or more, more preferably 10 mol% or more, and still more preferably 20 mol%, based on the total constituent monomer units of the polymer block A. % or more.

The upper limit of the content of the structural unit derived from the imide group-containing vinyl compound is preferably 90 mol% or less, more preferably 70 mol% or less, and even more preferably is 65 mol% or less. In particular, it is more preferable that the content of the structural unit derived from the imide group-containing vinyl compound is 70 mol % or less, since the adhesiveness of the multi-block copolymer (P) can be sufficiently ensured. In the polymer block A, the content of the structural unit derived from the monomer is explained as follows: When the multi-block copolymer (P) has a plurality of polymer blocks A in one molecule, the content of the structural unit derived from the monomer is It represents the total content in the combined block A.

Examples of the (meth)acrylic monomer include alkyl (meth)acrylate compounds, alkoxyalkyl (meth)acrylate compounds, and (meth)acrylamide compounds. Among these, the alkyl (meth)acrylate compound is a chain alkyl ester of (meth)acrylic acid, and specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylate. Isopropyl acid, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, (meth)acrylic acid 2 - Ethylhexyl, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, etc. Can be mentioned. As the alkyl (meth)acrylate compound, one or more of these can be used.

Examples of the alkoxyalkyl (meth)acrylate compounds include methoxymethyl (meth)acrylate, ethoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and n-(meth)acrylate. Propoxyethyl, n-butoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, n-propoxypropyl (meth)acrylate, n-butoxypropyl (meth)acrylate, ( Examples include methoxybutyl meth)acrylate, ethoxybutyl (meth)acrylate, n-propoxybutyl (meth)acrylate, and n-butoxybutyl (meth)acrylate. As the alkoxyalkyl (meth)acrylate compound, one or more of these can be used.

(Meth)acrylamide compounds include (meth)acrylamide, tert-butyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, (meth)acryloylmorpholine, N -methylol acrylamide, N-methoxymethyl acrylamide, N-methoxybutylacrylamide, diacetone (meth)acrylamide, and the like. As the (meth)acrylamide compound, one or more of these can be used.

When polymer block A has a structural unit derived from a (meth)acrylic monomer, the content of the structural unit derived from a (meth)acrylic monomer is equal to the total constituent monomer of polymer block A. It is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, based on the unit. Furthermore, the upper limit of the content of the structural unit derived from the (meth)acrylic monomer with respect to all the constituent monomer units of the polymer block A is not particularly limited; It is preferably 70 mol% or less, more preferably 50 mol% or less, and even more preferably 40 mol% or less.

The styrene compound has a property of improving the polymerizability of an imide group-containing vinyl compound (preferably a maleimide compound). Therefore, when an imide group-containing vinyl compound is used as the constituent monomer unit of the polymer block A, it is preferable to improve the polymerizability of the imide group-containing vinyl compound by using a styrene compound in combination. When the multi-block copolymer (P) includes a polymer block having a structural unit derived from a styrene compound and a structural unit derived from an imide group-containing vinyl compound, in the polymer block, the imide group-containing vinyl compound The content of the structural unit derived from the styrene compound is preferably 0.01 to 100 mol, more preferably 0.1 to 10 mol, and still more preferably 0.01 to 100 mol, per 1 mol of the structural unit derived from styrene compound. The amount is 2 to 5 mol, particularly preferably 0.5 to 1.5 mol.

Polymer block A is selected from the group consisting of styrenic compounds and imide group-containing vinyl compounds, in that a multi-block copolymer (P) with better heat resistance and adhesiveness can be obtained. It is preferable to have at least a structural unit derived from at least one type of compound (hereinafter also referred to as "structural unit U1"), which includes a styrene compound and an imide group-containing vinyl compound, an alkyl (meth)acrylate compound, and It is more preferable to have a structural unit derived from at least one compound selected from the group consisting of alkoxyalkyl (meth)acrylate compounds. The proportion of the structural unit U1 in the polymer block A is preferably 30 mol% or more, more preferably 50 mol% or more, and 70 mol% or more, based on the total constituent monomer units that the polymer block A has. More preferably, it is mol% or more. The number of structural units U1 that the polymer block A has can be one or more.

When the multi-block copolymer (P) has multiple types of polymer blocks A in one molecule, the multi-block copolymer (P) has a first polymer block A ¹ as the polymer block A, It has a second polymer block ^A2 having a different composition of constituent monomer units from the first polymer block ^A1 . In this case, in the plurality of polymer blocks A of the multi-block copolymer (P), polymer block A ¹ and polymer block A ² further undergo phase separation, resulting in phase separation consisting of polymer block A. It becomes possible to make the structure smaller. As a result, the polymer easily softens at a temperature higher than the glass transition point of one of the first polymer block ^A1 and the second polymer block ^A2 , and can adhere to the adherend at high temperatures. This is preferable in that it becomes possible to obtain a multiblock copolymer (P) that exhibits higher peel strength under these conditions.

The compositions of the constituent monomer units of the first polymer block A ¹ and the second polymer block A ² are not particularly limited. From the viewpoint of improving cohesive force, the first polymer block A ¹ preferably has a structural unit derived from a styrene compound, and from the viewpoint of obtaining a polymer block exhibiting a high glass transition point and reactivity. From this viewpoint, it is preferable to have a structural unit derived from a styrene compound and a structural unit derived from an imide group-containing vinyl compound. In the first polymer block ^A1 , the structural unit derived from the styrene compound is preferably 10 mol% or more, more preferably 20 mol% or more, and still more preferably 30 mol% or more. Further, the structural unit derived from the styrene compound in the first polymer block ^A1 is preferably 90 mol% or less, more preferably 80 mol% or less, and still more preferably 70 mol% or less.

The second polymer block A ² is composed of the monomer units contained in the first polymer block A ¹ and the monomers contained in the polymer block B in that it can further improve fluidity during thermocompression bonding. It is preferable that it has a unit. From this point of view, the second polymer block ^A2 preferably has a structural unit derived from a (meth)acrylic monomer, and a structural unit derived from a (meth)acrylic monomer and an imide group. It is more preferable to have a structural unit derived from a vinyl compound contained therein. Among these, from the viewpoint of achieving both fluidity during thermocompression bonding and peel strength under high temperature conditions, the second polymer block ^A2 is composed of an alkyl (meth)acrylate compound and an alkoxyalkyl (meth)acrylate compound. It is preferable to have a structural unit derived from at least one selected from the group consisting of compounds and a structural unit derived from an imide group-containing vinyl compound, and an alkyl acrylate compound having an alkyl group having 1 to 4 carbon atoms and a carbon It is particularly preferable to have at least one kind selected from the group consisting of alkoxyalkyl acrylate compounds having several alkoxyalkyl groups and a structural unit derived from a maleimide compound.

Polymer block A is a monomer copolymerizable with the above-mentioned monomers and contains structural units derived from monomers other than those mentioned above, within a range that does not impair the effect of the multi-block copolymer (P). may have. Examples of the monomer include amide group-containing vinyl compounds (N-vinylacetamide, N-vinylformamide, N-vinylisobutyramide, etc.), N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylamino Examples include ethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. These compounds may be used alone or in combination of two or more.

The glass transition point TgA of the polymer block A may be 50° C. or higher, but is preferably from the viewpoint of imparting good heat resistance and good adhesion in a high temperature environment to the multi-block copolymer (P). is 60°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher. In addition, the glass transition point TgA is preferably 350°C or lower, and preferably 280°C or lower, since there is a high degree of freedom in the usable constituent monomer units and the heating temperature during bonding can be lowered. The temperature is more preferably 270°C or lower, even more preferably 260°C or lower.

When the multi-block copolymer (P) has a first polymer block A ¹ and a second polymer block A ² , the glass transition point of the first polymer block A ¹ and the second polymer block Preferably, the temperature is different from the glass transition point of ^A2 . Specifically, the glass transition point of the first polymer block ^A1 is preferably 120°C or higher, more preferably 130°C or higher, even more preferably 150°C or higher, and even more preferably 170°C. It is particularly preferable that it is above. The glass transition point of the second polymer block ^A2 is preferably less than 120°C, more preferably 110°C or less. Further, the temperature difference between the glass transition point of the first polymer block ^A1 and the glass transition point of the second polymer block ^A2 is preferably 30°C or higher, more preferably 50°C or higher, and still more preferably 70°C or higher. ℃ or higher is preferable because the effect of achieving both fluidity during thermocompression bonding and peel strength under high temperature conditions can be sufficiently obtained.

In addition, in this specification, the glass transition point of a polymer is a value measured by differential scanning calorimetry (DSC). The details of the measurement method can follow the operations described in the Examples below. The glass transition point of each polymer block is a value determined by producing a homopolymer of the polymer block to be measured and performing DSC measurement of the homopolymer. The glass transition point of the polymer can be arbitrarily selected by changing the type and composition of the constituent monomers.

The number average molecular weight of polymer block A is preferably in the range of 500 to 40,000. When the number average molecular weight is 500 or more, the cohesive force of the multi-block copolymer (P) can be sufficiently ensured, and when it is 40,000 or less, the peel strength against the adherend can be made sufficiently high. This is preferable because it allows for The number average molecular weight of the polymer block A is more preferably 1,000 or more, still more preferably 2,000 or more, even more preferably 6,000 or more, particularly preferably 9,000 or more. Further, the number average molecular weight of the polymer block A is more preferably 35,000 or less, still more preferably 30,000 or less, particularly preferably 25,000 or less. The molecular weight of polymer block A is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

In addition, when a plurality of polymer blocks A exist in one molecule of the multi-block copolymer (P), the "number average molecular weight of the polymer block A" means that one molecule of the multi-block copolymer (P) It means the number average molecular weight of the entire plurality of polymer blocks A. For example, when the multi-block copolymer (P) is an ABABA type pentablock copolymer, the number average molecular weight of the polymer block A in the pentablock copolymer is the number average molecular weight of the three polymer blocks A. This is the sum of the molecular weights.

When the multi-block copolymer (P) has a first polymer block A ¹ and a second polymer block A ² , the number average molecular weight per polymer block A (i.e., one first The number average molecular weight of each of the polymer block A ¹ and one second polymer block A ² ) is preferably in the range of 500 to 30,000. The number average molecular weight per polymer block A is more preferably 1,000 or more, still more preferably 1,500 or more, particularly preferably 2,000 or more. Further, the number average molecular weight per polymer block A is more preferably 25,000 or less, still more preferably 20,000 or less, particularly preferably 15,000 or less.

It is preferable that the polymer block A has the property of phase-separating from the polymer block B. Having such properties is preferable in that the multi-block copolymer (P) can easily form a microphase-separated structure. A person skilled in the art can easily design a polymer block A that phase separates from a polymer block B based on the common general knowledge at the time of filing this application. For example, the difference ΔSP (absolute value) when comparing the SP value of polymer block A and the SP value of polymer block B calculated by a known calculation method of SP value, which is a solubility parameter (for example, Fedors method), is 0. .01 or more. The difference ΔSP may be, for example, 0.05 or more, 0.1 or more, 0.2 or more, or 0.5 or more. In the case of the Fedors method, the SP value is R. F. It can be calculated by the calculation method described in "Polymer Engineering and Science" 14(2), 147 (1974) written by John Fedors. In addition, the SP value can be determined by observing the structure of the intended multi-block copolymer (P) using an electron microscope, atomic force microscope, small-angle X-ray scattering, etc. to easily estimate the phase separation between blocks. You can also do it.

(Polymer block B)
Polymer block B is a polymer block having a glass transition point of 10° C. or lower and exhibits adhesiveness. When the glass transition point (hereinafter also referred to as "glass transition point TgB") of polymer block B is 10° C. or lower, the multi-block copolymer (P) exhibits good adhesiveness. The multi-block copolymer (P) may have only one polymer block B in one molecule, or may have a plurality of polymer blocks B. The number of polymer blocks B that the multi-block copolymer (P) has is preferably one or two from the viewpoint of efficient production. When the multi-block copolymer (P) has a plurality of polymer blocks B in one molecule, the structures of each block of the plurality of polymer blocks B may be the same or different from each other.

Polymer block B is a polymer block whose main component is a structural unit derived from a (meth)acrylic monomer. The structural unit derived from the (meth)acrylic monomer that polymer block B has is preferably 50 mol% or more, and 70 mol% or more based on the total constituent monomer units of polymer block B. The content is more preferably 80 mol% or more, even more preferably 90 mol% or more. In addition, in the polymer block B, the content of the structural unit derived from the monomer is explained when the multi-block copolymer (P) has a plurality of polymer blocks B in one molecule. Refers to the total content in combined block B.

Polymer block B is derived from a compound represented by the following formula (2) as a constituent monomer unit in that a polymer having a sufficiently low glass transition point TgB and good adhesiveness can be obtained. It is preferable to have a structural unit.
_CH2 = ^CR1 -C(=O)-O-( ^R2O )n- ^R3 ...(2)
(In formula (2), R ¹ represents a hydrogen atom or a methyl group, R ² represents a linear or branched alkylene group having 2 to 6 carbon atoms, and R ³ represents a hydrogen atom or a C 1 to 20 alkylene group. Represents an alkyl group or an aryl group having 6 to 20 carbon atoms. n represents 0 or an integer of 1 to 100. When n is 2 or more, multiple R ^3s in the formula may be the same or different from each other. .)

Examples of the compound represented by the above formula (2) include alkyl (meth)acrylate compounds, alkoxyalkyl (meth)acrylate compounds, hydroxyalkyl (meth)acrylate compounds, and polyalkylene glycol mono(meth)acrylate compounds. etc. Regarding these specific examples, as the alkyl (meth)acrylate compound and the alkoxyalkyl (meth)acrylate compound, the alkyl (meth)acrylate compound and Examples include alkoxyalkyl (meth)acrylate compounds and the like.

The hydroxyalkyl (meth)acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. , 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

The polyalkylene glycol mono(meth)acrylate compound is a compound where n in the above formula (2) is 2 or more. n is preferably 50 or less, more preferably 30 or less. Specific examples of polyalkylene glycol mono(meth)acrylate compounds include polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and polyethylene glycol-polypropylene glycol mono(meth)acrylate. ) acrylate, etc.

Polymer block B is derived from at least one monomer (hereinafter also referred to as "monomer C1") selected from the group consisting of an alkyl (meth)acrylate compound and an alkoxyalkyl (meth)acrylate compound. It is preferable to have a structural unit that does the following. In polymer block B, the content of structural units derived from monomer C1 is preferably 20 to 100 mol%, and 50 to 100 mol%, based on the total constituent monomer units of polymer block B. %, more preferably 80 to 100 mol %, even more preferably 90 to 100 mol %, particularly preferably 95 to 100 mol %. When the content of the structural unit derived from the monomer C1 is within the above range, a multi-block copolymer (P) with good adhesive properties tends to be obtained.

As the monomer C1, among the above, alkyl acrylate compounds having an alkyl group having 4 to 12 carbon atoms and 2 carbon atoms are used because they can obtain a multi-block copolymer (P) with excellent flexibility. At least one selected from the group consisting of alkoxyalkyl acrylate compounds having ~8 alkoxyalkyl groups is preferred. In addition, when taking adhesive performance into consideration, the monomer C1 is selected from the group consisting of an alkyl acrylate compound having an alkyl group having 4 to 8 carbon atoms and an alkoxyalkyl acrylate compound having an alkoxyalkyl group having 2 to 3 carbon atoms. At least one selected type is more preferred.

Polymer block B may have only structural units derived from the compound represented by the above formula (2), but is a compound different from the compound represented by the above formula (2), and It may further have a structural unit derived from a compound copolymerizable with the compound represented by the above formula (2) (hereinafter also referred to as "other monomer"). The other monomer may be a (meth)acrylic monomer or may be a monomer other than the (meth)acrylic monomer. As other monomers, one type or two or more types can be used.

When producing the polymer block B, by using a vinyl monomer having a crosslinkable functional group, the polymer block B can have a structure having a crosslinkable structural unit. It is preferable that the polymer block B has a crosslinkable structural unit because the heat resistance and high temperature adhesiveness of the adhesive layer obtained using the adhesive composition can be improved. Vinyl monomers having crosslinkable functional groups are not particularly limited, but include, for example, unsaturated carboxylic acids, unsaturated acid anhydrides, hydroxy group-containing vinyl compounds, epoxy group-containing vinyl compounds, and reactive silicon group-containing vinyl compounds. etc.

Specific examples of vinyl monomers having crosslinkable functional groups include (meth)acrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, cinnamic acid, and unsaturated dicarboxylic acids as unsaturated carboxylic acids. Monoalkyl esters (monoalkyl esters of maleic acid, fumaric acid, itaconic acid, citraconic acid, etc.), etc.; unsaturated acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, etc.;
Hydroxyalkyl (meth)acrylate compounds and polyalkylene glycol monomers exemplified as monomers that can be used in the production of polymer block A exemplified as compounds represented by formula (2) above as hydroxy group-containing vinyl compounds (meth)acrylate compounds, unsaturated alcohols such as allyl alcohol, and hydroxyl group-containing styrenic compounds such as o-hydroxystyrene, m-hydroxystyrene, and p-hydroxystyrene;
As the epoxy group-containing vinyl compound, epoxy group-containing (meth)acrylic acid ester compounds such as glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, 3,4-epoxycyclohexylmethyl (meth)acrylate, etc. ;
Vinyl silane compounds such as vinyltrimethoxysilane, vinyltritoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane as reactive silicon group-containing vinyl compounds; trimethoxysilylpropyl (meth)acrylate, triethoxy (meth)acrylate Silyl group-containing (meth)acrylic acid ester compounds such as silylpropyl, methyldimethoxysilylpropyl (meth)acrylate, and dimethylmethoxysilylpropyl (meth)acrylate; silyl group-containing vinyl ether compounds such as trimethoxysilylpropyl vinyl ether; Examples include silyl group-containing vinyl ester compounds such as vinyl methoxysilyl undecanoate. Further, as the vinyl monomer having a crosslinkable functional group, an oxazoline group-containing vinyl compound, an isocyanate group-containing vinyl compound, or the like may be used. In producing the polymer block B, one type or two or more types of vinyl monomers having a crosslinkable functional group can be used.

When polymer block B has a crosslinkable structural unit, the content of the crosslinkable structural unit is preferably 0.01 mol% or more, more preferably is 0.1 mol% or more, more preferably 0.5 mol% or more. By setting the content of crosslinkable structural units in polymer block B to 0.01 mol% or more, a multiblock that forms a good crosslinked structure and exhibits higher heat resistance and better adhesion under high temperature conditions. It becomes easier to obtain the copolymer (P). In addition, the upper limit of the content of the crosslinkable structural unit is not particularly limited, but from the viewpoint of ensuring sufficient flexibility of the resulting adhesive layer, The content is preferably 30 mol% or less, more preferably 20 mol% or less, still more preferably 15 mol% or less, particularly preferably 10 mol% or less.

Among the above, the crosslinkable structural unit that polymer block B has is preferably a structural unit derived from a (meth)acrylic monomer. Among these, at least one selected from the group consisting of (meth)acrylic acid, hydroxyalkyl (meth)acrylate compounds, epoxy group-containing (meth)acrylic ester compounds, and silyl group-containing (meth)acrylic ester compounds. More preferably, it is a structural unit derived from a species monomer. Moreover, since the adhesive strength of the polymer block B tends to be high, it is particularly preferable that the crosslinkable structural unit is a structural unit derived from a hydroxyalkyl (meth)acrylate compound. As the hydroxyalkyl (meth)acrylate compound, from the viewpoint of adhesive performance, compounds having a hydroxyalkyl group having 2 to 8 carbon atoms are preferred, and compounds having a hydroxyalkyl group having 2 or 3 carbon atoms are particularly preferred.

When polymer block B has a structural unit derived from a hydroxyalkyl (meth)acrylate compound, the content of the structural unit derived from the hydroxyalkyl (meth)acrylate compound is determined from the viewpoint of forming a good crosslinked structure. It is preferably 0.01 mol% or more, more preferably 0.1 mol% or more, and still more preferably 0.5 mol% or more, based on all the constituent monomer units of polymer block B. In addition, from the viewpoint of ensuring sufficient flexibility of the adhesive layer, the content of structural units derived from the hydroxyalkyl (meth)acrylate compound is preferably set relative to all constituent monomer units of the polymer block B. is 20 mol% or less, more preferably 12 mol% or less, still more preferably 7 mol% or less.

In addition to the above, other monomers include, for example, aliphatic cyclic ester compounds of (meth)acrylic acid, alkenyl ester compounds of (meth)acrylic acid, aromatic ester compounds of (meth)acrylic acid, and aliphatic ester compounds of (meth)acrylic acid. Vinyl compounds, aromatic vinyl compounds, amide group-containing vinyl compounds, polyalkylene glycol mono(meth)acrylate compounds, polyfunctional (meth)acrylate compounds, polyfunctional alkenyl compounds, nitrile group-containing unsaturated compounds, dialkyl unsaturated dicarboxylic acids Examples include ester compounds. The amounts used can be appropriately set depending on each compound within a range that does not impair the effects of the present invention.

(Structure of multi-block copolymer (P))
As long as the multi-block copolymer (P) has a total of 4 or more polymer blocks A and polymer blocks B in one molecule, the number of polymer blocks A and polymer blocks B in one molecule and each The composition of the polymer block is not particularly limited. Multi-block copolymer (P) exhibits high peel strength under high temperature conditions and can also have sufficiently high peel strength under room temperature conditions. It is preferable to increase the proportion of A and the number of polymer blocks A.

From this point of view, in the multi-block copolymer (P), it is preferable that the number of polymer blocks A is larger than the number of polymer blocks B. Specifically, the number of polymer blocks A in one molecule is preferably greater than the number of polymer blocks B. It is preferable that the number is three or more. The number of polymer blocks A is more preferably 3 or more and 10 or less, and even more preferably 3 or more and 6 or less, from the viewpoint of efficiency when producing the multi-block copolymer (P). . In addition, the number of polymer blocks B in one molecule is not particularly limited, but from the viewpoint of efficiently producing a multi-block copolymer (P) that has sufficiently high peel strength both under high temperature conditions and room temperature conditions. From these, one or two pieces are preferable, and one piece is more preferable.

From the viewpoint of achieving both the effect of improving peel strength under high temperature conditions and room temperature conditions and manufacturing efficiency, the multi-block copolymer (P) has a total number of polymer blocks A and B of 4. Preferably, it is a block copolymer having 7 to 7 pieces. Specific examples of the multi-block copolymer (P) include the following block copolymers (1) to (9). In addition, in the following (1) to (9), A ¹ and A ² are both polymer blocks A, and among these, A ¹ is the first polymer block, and A ² is the second polymer block. be.

(1) Tetra block copolymer (A ¹ BA ² A ¹ ) consisting of polymer block A ¹ /polymer block B /polymer block A ² /polymer block A ¹ .
(2) A pentablock copolymer (A ¹ A ² BA ² A ¹ ) consisting of polymer block A ¹ /polymer block A ² /polymer block B /polymer block A ² /polymer block A ¹ .
(3) A pentablock copolymer (A ² A ¹ BA ¹ A ² ) consisting of polymer block A ² /polymer block A ¹ /polymer block B /polymer block A ¹ /polymer block A ² .
(4) A (A ¹ BA ¹ BA ¹ ) pentablock copolymer consisting of polymer block A 1 /polymer block B/polymer block ^{A 1} /polymer block B/polymer block A ¹ .
(5) A (A ¹ BA ² BA ¹ ) pentablock copolymer consisting of polymer block A 1 /polymer block B/polymer block ^{A 2} /polymer block B/polymer block A ¹ .
(6) A (A ² BA ¹ BA ² ) pentablock copolymer consisting of polymer block A ² /polymer block B/polymer block A ¹ /polymer block B/polymer block A ² .
(7) Hexablock (A ¹ BA ¹ BA ¹ A ² ) consisting of polymer block A ¹ /polymer block B /polymer block A ¹ /polymer block B /polymer block A ¹ /polymer block A ² Copolymer.
(8) Consisting of polymer block A ¹ /polymer block B / polymer block A ¹ /polymer block B / polymer block A ¹ /polymer block B / polymer block A ¹ (A ¹ BA ¹ BA ^{1 BA1} ) Heptablock copolymer.
(9) Consisting of polymer block A ¹ /polymer block A ² /polymer block B /polymer block A ¹ /polymer block B /polymer block A ² /polymer block A ¹ (A ¹ A ² BA ¹ BA ² A ¹ ) heptablock copolymer.

When the multi-block copolymer (P) is a polymer with a symmetrical structure, polymer block A and polymer block B tend to form a pseudo-crosslinked structure, which improves peel strength under high temperature conditions and room temperature environments. This is preferable in that an excellent block copolymer can be obtained. From this point of view, among the above (1) to (9), (2) to (4), (8) and (9) are preferable for the multi-block copolymer (P), and (2) to (4) are preferable. ) is more preferable. Further, the multi-block copolymer (P) is preferably a pentablock copolymer in which the total number of polymer blocks A and B is 5 in terms of production efficiency.

The multi-block copolymer (P) may further have polymer blocks other than polymer block A and polymer block B (hereinafter also referred to as "other polymer blocks"). The proportion of other polymer blocks in the multi-block copolymer (P) is preferably 10 mol% or less, and 5 mol% or less, based on the total monomer units of the multi-block copolymer (P). More preferably, it is 1 mol% or less.

The ratio of polymer block A to polymer block B in the multi-block copolymer (P) is the ratio of polymer block A to the total amount of polymer block A and polymer block B (hereinafter referred to as "hard segment ratio"). ) is preferably 5 mol % or more. When the hard segment ratio is 5 mol% or more, the polymer has a polymer block A that forms a phase-separated structure and can serve as a pseudo-crosslinking point, and a polymer block B that serves as a soft segment, which provides excellent performance under high-temperature conditions. It is easy to obtain an adhesive that exhibits peel strength. In addition, when the hard segment ratio is 40 mol% or less, the polymer in the adhesive layer exhibits sufficient fluidity during thermal bonding, ensuring high adhesive strength and increasing peel strength under room temperature conditions. Therefore, it is preferable.

From this viewpoint, the hard segment ratio is more preferably 7 mol% or more, still more preferably 10 mol% or more, and even more preferably 11 mol% or more. Further, the hard segment ratio is more preferably 30 mol% or less, even more preferably 25 mol% or less, even more preferably 20 mol% or less, and particularly preferably 17 mol% or less. preferable. Note that the hard segment ratio is a value calculated from the amount of monomer charged and the amount of monomer consumption measured by gas chromatograph (GC).

From the viewpoint of exhibiting good adhesive properties, the number average molecular weight (Mn) of the multi-block copolymer (P) is preferably 10,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. Particularly preferred is 80,000 or more. In addition, Mn of the multi-block copolymer (P) is preferably 1,000,000 or less, more preferably 700,000 or less, from the viewpoint of sufficiently ensuring processability such as good fluidity and coatability. , 500,000 or less is more preferable, and 300,000 or less is particularly preferable. The range of Mn of the multi-block copolymer (P) is preferably 10,000 or more and 1,000,000 or less, more preferably 30,000 or more and 700,000 or less, and still more preferably 50,000 or more. 500,000 or less. The molecular weight of the multi-block copolymer (P) is a polystyrene equivalent value measured by GPC.

Regarding the multi-block copolymer (P), the molecular weight distribution expressed as the ratio of weight average molecular weight (Mw) to Mn (Mw/Mn) is determined by forming a pseudo-crosslinked structure and improving adhesive properties (adhesiveness, cohesiveness, etc.). ) is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.5 or less. The lower limit of Mw/Mn of the multi-block copolymer (P) is not particularly limited and can be 1.0 or more.

The reason why the pressure-sensitive adhesive composition of the present invention is able to form a pressure-sensitive adhesive layer exhibiting high peel strength both at high temperatures and at room temperature is not clear, but the following may be considered. When an adhesive layer is formed from a block copolymer having a hard segment (polymer block A) and a soft segment (polymer block B), in the adhesive layer, due to microphase separation between the hard segment and the soft segment, , a sea-island structure consisting of hard segments is formed within the soft segments. At this time, when a triblock copolymer consisting of hard segment (A)-soft segment (B)-hard segment (A) is used as the block copolymer, the sea-island structure becomes relatively large. When a multi-block copolymer (P) is used, the sea-island structure can be made smaller by subdividing the hard segments. It is considered that this makes it easier for the hard segments and soft segments to mix in the multi-block copolymer (P). Therefore, in the multi-block copolymer (P), the hard segments act as crosslinking points at room and high temperatures and exhibit high adhesive strength, but at higher temperatures during thermocompression bonding, the hard segments tend to flow ( In other words, it is presumed that the multi-block copolymer (P) flows easily), which causes the multi-block copolymer (P) to firmly adhere to the adherend.

<Method for producing multi-block copolymer (P)>
The multi-block copolymer (P) has a polymer block A and a polymer block B, and as long as it is possible to obtain a polymer in which the total number of polymer blocks A and polymer blocks B is 4 or more. The manufacturing method is not particularly limited and can be obtained by any known manufacturing method. Examples of methods for producing the multi-block copolymer (P) include methods that utilize various controlled polymerization methods such as living radical polymerization and living anionic polymerization, and methods that couple polymers having functional groups with each other. be able to. Among these, the living radical polymerization method is preferred because it is easy to operate and can be applied to a wide range of monomers.

For living radical polymerization, any process such as a batch process, a semi-batch process, a dry continuous polymerization process, a continuous stirred tank type process (CSTR), etc. may be employed. Furthermore, various polymerization methods can be applied, such as bulk polymerization without using a solvent, solvent-based solution polymerization, water-based emulsion polymerization, mini-emulsion polymerization, or suspension polymerization.

There are no particular restrictions on the type of living radical polymerization, and examples include reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxy radical polymerization (NMP), atom transfer radical polymerization (ATRP), and organic tellurium compounds. Various polymerization methods can be employed, such as a polymerization method using an organic antimony compound (TERP method), a polymerization method using an organic antimony compound (SBRP method), a polymerization method using an organic bismuth compound (BIRP method), and an iodine transfer polymerization method. Among these, the RAFT method, NMP method and ATRP method are preferred from the viewpoint of polymerization controllability and ease of implementation.

In the RAFT method, controlled polymerization proceeds via a reversible chain transfer reaction in the presence of a specific polymerization control agent (RAFT agent) and a general free radical polymerization initiator. As the RAFT agent, various known RAFT agents such as dithioester compounds, xanthate compounds, trithiocarbonate compounds, and dithiocarbamate compounds can be used. As the RAFT agent, a monofunctional agent having only one active site may be used, or a bifunctional or more functional agent may be used. It is preferable to use a bifunctional RAFT agent because it is easy to efficiently obtain a block copolymer with a multi-block structure. Further, the amount of the RAFT agent used is appropriately adjusted depending on the monomer used, the type of RAFT agent, etc.

Known radical polymerization initiators such as azo compounds, organic peroxides, and persulfates can be used as polymerization initiators during polymerization by the RAFT method, but they are safe and easy to handle, and are suitable for use during radical polymerization. Azo compounds are preferred because side reactions are less likely to occur. Specific examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2, 4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1- carbonitrile), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), and the like. Only one type of radical polymerization initiator may be used, or two or more types may be used in combination. The usage ratio of the radical polymerization initiator is not particularly limited, but from the viewpoint of performing the polymerization reaction stably and obtaining a polymer with a smaller molecular weight distribution, the usage amount of the radical polymerization initiator is set to 0.000% per mole of the RAFT agent. The amount is preferably 0.01 mol or more and 0.5 mol or less, and more preferably 0.01 mol or more and 0.2 mol or less.

The reaction temperature during the polymerization reaction by the RAFT method is preferably 40°C or more and 100°C or less, more preferably 45°C or more and 90°C or less, and even more preferably 50°C or more and 80°C or less. It is preferable that the reaction temperature is 40° C. or higher because the polymerization reaction can proceed smoothly. Further, it is preferable that the reaction temperature is 100° C. or less, since side reactions can be suppressed and restrictions regarding usable initiators and solvents are relaxed.

（式（３）中、Ｒ^１は炭素数１～２のアルキル基又は水素原子であり、Ｒ^２は炭素数１～２のアルキル基又はニトリル基であり、Ｒ^３は－（ＣＨ_２）ｍ－、ｍは０～２の整数であり、Ｒ^４及びＲ^５は、それぞれ独立に炭素数１～４のアルキル基である。式中の複数のＲ^４は、互いに同一でも異なっていてもよい。） In the NMP method, a specific alkoxyamine compound having nitroxide or the like is used as a living radical polymerization initiator, and polymerization proceeds via nitroxide radicals derived from the living radical polymerization initiator. In the production of the multi-block copolymer (P), there is no particular restriction on the type of nitroxide radical, and commercially available nitroxide-based polymerization initiators can be used. From the viewpoint of polymerization controllability when polymerizing a monomer containing an acrylate, it is preferable to use a compound represented by the following formula (3) as the nitroxide compound.

(In formula (3), R ¹ is an alkyl group having 1 to 2 carbon atoms or a hydrogen atom, R ² is an alkyl group having 1 to 2 carbon atoms or a nitrile group, and R ³ is -(CH ₂ )m -, m are integers of 0 to 2, and R ⁴ and R ⁵ are each independently an alkyl group having 1 to 4 carbon atoms. Plural R ⁴ in the formula may be the same or different from each other. .)

The nitroxide compound represented by the above formula (3) undergoes primary dissociation upon heating to approximately 70 to 80°C, and undergoes an addition reaction with the vinyl monomer. At this time, it is possible to obtain a polyfunctional polymerization precursor by adding a nitroxide compound to a vinyl monomer having two or more vinyl groups. Next, the vinyl monomer can be subjected to living polymerization by subjecting the polymerization precursor to secondary dissociation under heating. In this case, since the polymerization precursor has two or more active sites in the molecule, a polymer with a narrower molecular weight distribution can be obtained. From the viewpoint of easily obtaining the multi-block copolymer (P) efficiently, it is preferable to use a bifunctional polymerization precursor having two active sites in the molecule. The amount of the nitroxide compound to be used is appropriately adjusted depending on the type of monomer and nitroxide compound used.

（式（４）中、Ｒ^６及びＲ^７は、それぞれ独立に炭素数１～４のアルキル基である。式中の複数のＲ^６は互いに同一でも異なっていてもよく、式中の複数のＲ^７は互いに同一でも異なっていてもよい。） When producing the multi-block copolymer (P) by the NMP method, 0.001 to 0.001 to 0.00% of the nitroxide radical represented by the following formula (4) is added to 1 mole of the nitroxide compound represented by the above formula (3). Polymerization may be carried out by adding within the range of 2 moles.

(In formula (4), R ⁶ and R ⁷ are each independently an alkyl group having 1 to 4 carbon atoms. R ⁶ in the formula may be the same or different from each other, and R 6 in the formula ^R7 may be the same or different.)

By adding 0.001 mol or more of the nitroxide radical represented by the above formula (4), the time required for the concentration of the nitroxide radical to reach a steady state can be shortened. This is preferable in that it becomes possible to control the polymerization to a higher degree and to obtain a polymer with a narrower molecular weight distribution. On the other hand, if the amount of nitroxide radical added is too large, polymerization may not proceed. A more preferred amount of nitroxide radical added is in the range of 0.01 to 0.5 mol, and a still more preferred amount is in the range of 0.05 to 0.2 mol, per 1 mol of the nitroxide compound.

The reaction temperature in the NMP method is preferably 50°C or more and 140°C or less, more preferably 60°C or more and 130°C or less, even more preferably 70°C or more and 120°C or less, particularly preferably 80°C or more and 120°C. It is as follows. When the reaction temperature is 50° C. or higher, the polymerization reaction can proceed smoothly. On the other hand, if the reaction temperature is 140° C. or lower, side reactions such as radical chain transfer tend to be suppressed.

In the ATRP method, a polymerization reaction is generally performed using an organic halide as an initiator and a transition metal complex as a catalyst. The organic halide used as the initiator may be monofunctional, or may be difunctional or more functional. It is preferable to use a bifunctional compound from the viewpoint of efficiently obtaining the multi-block copolymer (P). As the type of halogen, bromide and chloride are preferred. The reaction temperature in the ATRP method is preferably 20°C or more and 200°C or less, more preferably 50°C or more and 150°C or less. It is preferable to set the reaction temperature to 20° C. or higher because the polymerization reaction can proceed smoothly.

When obtaining a pentablock copolymer consisting of polymer block A ¹ /polymer block A ² /polymer block B /polymer block A ² /polymer block A ¹ by the living radical polymerization method, for example, each block is The desired pentablock copolymer may be obtained by sequential polymerization. In this case, first, as a first polymerization step, a polymer block A ¹ is obtained using constituent monomers of the polymer block A ¹ . Next, as a second polymerization step, the constituent monomers of polymer block A ² are used to obtain polymer block A 2, and as a third polymerization step, polymer block A ² is obtained using the constituent monomers of polymer block B. Then, as a fourth polymerization step, polymerization is performed using the constituent monomers of polymer block A ² , and further, as a fifth polymerization step, polymerization is performed using the constituent monomers of polymer block A ¹ . A pentablock copolymer of the A ¹ A ² BA ² A ¹ type can be obtained. As the polymerization initiator, it is preferable to use the monofunctional polymerization initiator or polymerization precursor described above.

It is preferable to manufacture by a method including the three-stage polymerization process shown below, since the desired product can be obtained more efficiently. That is, in the first polymerization step, the constituent monomers of the polymer block A ¹ are used to obtain the polymer block A ¹ , and then in the second polymerization step, the constituent monomers of the polymer block A ² are polymerized. Polymer block ^A2 is obtained. As a result, an A ¹ A ² A ¹ type triblock copolymer consisting of polymer block A ¹ -polymer block A ² -polymer block A ¹ can be obtained. Furthermore, as a third polymerization step, the constituent monomers of polymer block B are polymerized to obtain polymer block B. This produces an A ^{1 A 2} BA 2 A ¹ type pentablock copolymer consisting of polymer block A ¹ -polymer block A ² -polymer block B - polymer block A ² -polymer block A ¹ . Obtainable. In this case, as the polymerization initiator, it is preferable to use one or more of a bifunctional polymerization initiator, a polymerization precursor, and a polymerization control agent. According to this method, the manufacturing process can be simplified compared to the case where each block is manufactured by sequential polymerization.

Polymerization of the multi-block copolymer (P) may be carried out in the presence of a chain transfer agent, if necessary. Known chain transfer agents can be used, and specifically, ethanethiol, 1-propanethiol, 2-propanethiol, 1-butanethiol, 2-butanethiol, 1-hexanethiol, 2-hexane. Alkyl groups having 2 to 20 carbon atoms such as thiol, 2-butylbutane-1-thiol, 1,1-dimethyl-1-pentanethiol, 1-dodecanethiol, tert-tetradecanethiol, 1-hexadecanethiol and 1-octadecanethiol In addition to alkylthiol compounds having the following, examples include mercaptoacetic acid, mercaptopropionic acid, 2-mercaptoethanol, and the like. As the chain transfer agent, one or more of these can be used.

In producing the multi-block copolymer (P), a polymerization solvent known in living radical polymerization can be used. Specifically, aromatic compounds such as benzene, toluene, xylene and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate; ketone compounds such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, dimethyl sulfoxide, Examples include alcohol and water. Alternatively, the polymerization may be carried out in a manner such as bulk polymerization without using a polymerization solvent.

<Other ingredients>
The multi-block copolymer (P) can be used alone as an adhesive material, but if necessary, components such as polymers and additives other than the multi-block copolymer (P) (hereinafter referred to as "other components") may be used. ) may be used by blending it into the adhesive composition. Below, other components that may be blended into the present adhesive composition will be explained.

(Crosslinking agent)
When the multi-block copolymer (P) has a crosslinkable functional group in at least one of polymer block A and polymer block B, a crosslinking agent capable of reacting with the crosslinkable functional group is blended into the adhesive composition. Good too. In addition, by further performing heat treatment or the like as necessary, an adhesive suitable for the intended use can be obtained.

As a crosslinking agent (curing agent), a glycidyl compound having two or more glycidyl groups, an isocyanate compound having two or more isocyanate groups, an aziridine compound having two or more aziridinyl groups, an oxazoline compound having an oxazoline group, a metal chelate compound, Examples include butylated melamine compounds. Among these, isocyanate compounds are preferred because they have excellent adhesive properties under high temperature conditions.

Specific examples of crosslinking agents include glycidyl compounds such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and tetraglycidyl xylene diamine. , 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, polyfunctional glycidyl compounds such as trimethylolpropane polyglycidyl ether;
Isocyanate compounds include diphenylmethane diisocyanate (MDI), tolylene diisocyanate, naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), etc. Aromatic isocyanate compounds; aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI); isophorone diisocyanate (IPDI), cyclohexyl diisocyanate (CHDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI) ); Modified isocyanate compounds such as urethane modified products, dimers, trimers, carbodiimide modified products, urea modified products, isocyanurate modified products, oxazolidone modified products, isocyanate group-terminated prepolymers, etc. ;
As the aziridine compound, 1,6-bis(1-aziridinylcarbonylamino)hexane, 1,1'-(methylene-di-p-phenylene)bis-3,3-aziridylurea, ethylenebis-(2-aziridylurea), lysinylpropionate), 2,4,6-triaziridinyl-1,3,5-triazine, and trimethylolpropane-tris-(2-aziridinylpropionate).

When the adhesive composition contains a crosslinking agent, its content is not particularly limited, but is usually 0.01 to 10% by mass, preferably 0.01 to 10% by mass, based on the content of the multiblock copolymer (P). The amount is 0.03 to 5% by weight, more preferably 0.05 to 2% by weight.

(tackifier)
The adhesive composition may further contain a tackifier. Examples of the tackifier include rosin derivatives such as rosin ester, gum rosin, tall oil rosin, hydrogenated rosin ester, maleated rosin, and disproportionated rosin ester; terpene phenol resin, α-pinene, β-pinene, limonene, etc. (hydrogenated) petroleum resins; coumaron-indene resins; hydrogenated aromatic copolymers; styrene resins; phenolic resins; xylene resins; (meth)acrylic acid ester oligomers, etc. . One type of tackifier may be used alone, or two or more types may be used in combination.

As the tackifier, a (meth)acrylic acid ester oligomer can be suitably used from the viewpoint of transparency and the like. The glass transition point of the (meth)acrylic ester oligomer used as a tackifier is usually 10 to 300°C, preferably 15 to 250°C, more preferably 20 to 200°C, even more preferably 30 to 150°C. It is. When the glass transition point of the (meth)acrylic ester oligomer is within the above range, the effect of improving adhesion by adding the (meth)acrylic ester oligomer can be further enhanced. More specifically, a (meth)acrylic acid ester oligomer having a glass transition point of 30 to 150° C. and a polystyrene equivalent number average molecular weight of 500 to 10,000 measured by GPC can be suitably used.

The content of the tackifier is preferably 0 to 40% by mass, more preferably 0 to 20% by mass, and even more preferably 0 to 10% by mass, based on the total amount of the multiblock copolymer (P). %.

Other additives that may be added to the adhesive composition include, for example, plasticizers, antioxidants, ultraviolet absorbers, anti-aging agents, flame retardants, fungicides, silane coupling agents, fillers, colorants, etc. can be mentioned. The content of the additive can be appropriately set depending on the various compounds within a range that does not impair the effects of the present invention.

The present adhesive composition may be a liquid composition in which the multiblock copolymer (P) and other components blended as necessary are dissolved or dispersed in a solvent. Examples of the solvent used for preparing the pressure-sensitive adhesive composition include an organic solvent capable of dissolving the multi-block copolymer (P), and an aqueous medium capable of dispersing the multi-block copolymer (P). Specific examples of the organic solvent include aprotic polar solvents, phenol solvents, alcohol solvents, ester solvents, ketone solvents, ether solvents, hydrocarbon solvents, and the like. The organic solvent may be one type of these or a mixed solvent of two or more types.

When the adhesive composition is liquid, the solid content concentration in the adhesive composition (i.e., the ratio of the mass of components other than the solvent in the adhesive composition to the total mass of the adhesive composition) is not particularly limited. is preferably 1 to 70% by mass. It is preferable that the solid content concentration is 1% by mass or more because it is possible to form an adhesive layer with sufficient thickness. In addition, a solid content concentration of 70% by mass or less is preferred because good coatability can be ensured and a pressure-sensitive adhesive layer with a uniform thickness can be easily formed. The solid content concentration in the adhesive composition is more preferably 5 to 50% by mass, and still more preferably 10 to 45% by mass.

By coating the present adhesive composition on a support such as a separator to form an adhesive layer, adhesive products such as adhesive sheets and adhesive tapes can be obtained. This adhesive product can be used as an adhesive for bonding adherends together.

As the support, a resin film (separator) made of various resin materials, a base material, etc. are used. Examples of the resin material forming the separator include polyester resins such as polyethylene terephthalate, polyether sulfone resins, acetate resins, polycarbonate resins, and polyolefin resins. Examples of the base material include, but are not limited to, fiber fabrics, resin films, elastomer sheets, papers, metal films, and the like.

The adhesive layer is formed, for example, by applying a liquid adhesive composition to a support by a known coating method and removing the solvent, preferably by drying treatment such as heating. The heating temperature and heating time for forming the adhesive layer may be set appropriately as long as the solvent can be removed, and may be appropriately set depending on the solvent, solid content concentration, etc. of the adhesive composition.

The adhesive product may be in a so-called base material-less embodiment in which the adhesive layer is sandwiched between two types of separators having different peel strengths, or may be one in which one of the objects to be bonded is a base material. Further, there are no particular restrictions on the shape of the adhesive product, and it may be appropriately set depending on the usage situation. For example, the adhesive sheet may be sheet-like, roll-like, cut into strips, or may have any shape depending on the joint location. The thickness of the adhesive layer in the adhesive product may be appropriately set depending on the object to be joined, the area and shape of the joint, etc. The thickness of the adhesive layer is usually 1 to 200 μm. Further, in order to make the adhesive layer of the adhesive product have a desired thickness, the adhesive layer of the adhesive product may be formed by laminating a plurality of adhesive layers.

In order to bond the adhesive layer formed using the present adhesive composition to an adherend, first, by heating (preferably heat-pressing) the laminate in which the adhesive layer is bonded to the adherend. It can be carried out. When bonding the adhesive layer to the adherend by heat compression bonding, the pressure at the time of bonding may be appropriately set so as to obtain a desired bonding strength. Moreover, it is preferable that the heating temperature is lower than the heat resistance temperature of the adherend to be used. When the adhesive layer formed using this adhesive composition is made of fiber fabric as an adherend, the bonded area remains flexible even if the resin impregnates the network of the fiber fabric during thermocompression bonding, and the adhesive layer remains flexible and has a high It is preferable in that it can be bonded with strength.

The adhesive composition and adhesive product of the present invention can be applied to various uses. Specifically, it can be applied to, for example, clothing (including fashion goods), electronic equipment, interior or exterior parts for automobiles, optical equipment, handicraft supplies, toys, household goods, household goods, furniture, etc. can. In particular, the adhesive composition of the present disclosure can maintain the flexibility and feel of fabrics even on fibers, and can form an adhesive layer with high adhesiveness. , woven fabrics, knitted fabrics, nonwoven fabrics, lace, leather (natural leather, synthetic leather, artificial leather, etc.), fur, etc.), and in particular, it can be suitably used for textile fabrics for clothing.

The fiber fabrics to be joined are not particularly limited, and include fiber fabrics used for clothing and handicrafts, such as synthetic fibers such as polyester, polyamide, and acrylic fibers; recycled fibers such as rayon and cupro; semi-synthetic fibers such as acetate; Natural fibers such as cotton, linen, wool, etc. can be used as appropriate. Furthermore, the surfaces of the fiber fabrics to be joined may be subjected to water-repellent treatment or the like. Clothes manufactured using the present adhesive composition are not particularly limited, and include, for example, everyday clothes, Japanese clothes, ethnic clothes, underwear (for example, unsewn lingerie products, innerwear products, etc.), It can be used as an adhesive in the production of clothing for a wide range of purposes, such as clothes, tops, bottoms, outdoor gear, workwear, uniforms, formal wear, swimwear, sportswear, socks, hats, shoes, etc., as well as for handicrafts. .

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. In the following, "parts" and "%" mean parts by mass and % by mass unless otherwise specified. The analysis method and manufacturing method of the polymer used in the Examples and Comparative Examples are as follows.

<Molecular weight measurement>
Using a gel permeation chromatography device (model name "HLC-8320", manufactured by Tosoh Corporation), the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were obtained under the following conditions. Furthermore, the molecular weight distribution (Mw/Mn) was calculated from the obtained values.
○Measurement conditions Column: Tosoh TSKgel SuperMultiporeHZ-M x 4 Column temperature: 40°C
Eluent: Tetrahydrofuran Detector: RI
Flow rate: 600μL/min
In addition, when a polymer has a plurality of polymer blocks with the same monomer composition in one molecule, the total number average molecular weight of the polymer blocks is expressed as "Total number average molecular weight". That is, in the case of an A ¹ A ² BA ² A ¹ type pentablock copolymer, the "Total number average molecular weight" of the polymer block A ¹ is the sum of the two polymer blocks A ¹ that the pentablock copolymer has. is the sum of the number average molecular weights of

<Hard segment ratio of polymer>
The hard segment ratio of the polymer was identified and calculated from the amount of monomer charged and the amount of monomer consumed by gas chromatography (GC) measurement.

<Measurement of glass transition point (Tg)>
The glass transition point (Tg) of the polymer was determined from the intersection of the baseline of the heat flux curve obtained using a differential scanning calorimeter and the tangent at the inflection point. The heat flux curve shows that approximately 10 mg of the sample was cooled to -50°C, held for 5 minutes, then raised to 300°C at a rate of 10°C/min, then cooled to -50°C, held for 5 minutes, and then cooled to 10°C. The temperature was raised to 350° C./min.
Measuring equipment: DSC6220 manufactured by SII Nanotechnology
Measurement atmosphere: Under nitrogen atmosphere The glass transition temperature of each polymer block was determined by producing a homopolymer of the polymer block to be measured and performing differential scanning calorimetry (DSC) measurement according to the measurement method described above. .

1. Synthesis of polymer [Synthesis example 1]
In a 3L flask equipped with a stirrer and a thermometer, dibenzyl trithiocarbonate (hereinafter also referred to as "DBTTC") (1.33 g) was added as a RAFT agent, and 2,2'-azobis(2-methylbutyro) was added as a polymerization initiator. nitrile) (hereinafter also referred to as "ABN-E") (0.17 g), styrene (hereinafter also referred to as "St") (26 g) as a monomer, and N-phenylmaleimide (hereinafter also referred to as "PhMI"). ) (44 g) and acetonitrile (330 g) as a solvent were charged, the mixture was sufficiently degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70°C. After 3 hours, the reaction was stopped by cooling to room temperature. The obtained polymer block ^A1 had an Mn of 10,400. Next, 2-methoxyethyl acrylate (hereinafter also referred to as "MEA") (45 g) and PhMI (60 g) as monomers were charged into a 3 L flask containing the polymer block ^A1 , and thoroughly removed by nitrogen bubbling. Then, polymerization was started in a constant temperature bath at 70°C. After 6 hours, the reaction was stopped by cooling to room temperature. The obtained polymer block A ¹ A ² A ¹ had an Mn of 19,200. Furthermore, ABN-E (0.17 g) as a polymerization initiator, MEA (776 g) as a monomer, and 2-hydroxyethyl acrylate (hereinafter referred to as "HEA") were added to ^{a 3} L flask containing the polymer block A ¹ A 2 A 1. ) (50 g) and n-butyl acrylate (hereinafter referred to as "BA") (169 g) were charged, sufficiently degassed by nitrogen bubbling, and polymerization was started in a constant temperature bath at 70°C. After 6 hours, it was cooled to room temperature, the solid content concentration was adjusted to 30% by adding acetonitrile, and the A ¹ A ² BA ² A ¹ type multiblock copolymer (hereinafter referred to as "polymer (P A pressure-sensitive adhesive solution was obtained containing the following: The obtained multi-block copolymer had Mn of 118,000 and Mw/Mn of 2.06.

[Synthesis example 2]
A ¹ A ² BA ² A ¹ type was prepared in the same manner as in Synthesis Example 1 except that the RAFT agent, polymerization initiator, monomer, and type and amount of solvent used were changed as shown in Table 1. An adhesive solution containing a multi-block copolymer (hereinafter also referred to as "polymer (P-2)") was obtained. The obtained multi-block copolymer had Mn of 86,000 and Mw/Mn of 3.24. The molecular weight at the time of synthesizing the polymer block A ¹ (that is, the total number average molecular weight of the polymer block A ¹ ) is Mn 10,700, and the molecular weight at the time of synthesizing the polymer block A ¹ A ² A ¹ . The Mn was 16,300.

[Synthesis example 3]
A ¹ BA 1 BA ¹ type was obtained by polymerizing in the same manner as in Synthesis Example 1 except that the RAFT agent, polymerization initiator, monomer, and solvent type and amount used were changed as shown in Table ² . An adhesive solution containing a multi-block copolymer (hereinafter also referred to as "polymer (P-3)") was obtained. Specifically, first, polymer block A ¹ and polymer block A ¹ BA ¹ were obtained in order, and then St and MEA were polymerized as monomers into a 3 L flask containing polymer block A ¹ BA ¹ . An adhesive solution containing the polymer (P-3) was obtained by charging it together with an initiator and performing polymerization (second polymerization of polymer block ^A1 ). The obtained multi-block copolymer had Mn of 118,000 and Mw/Mn of 1.98. The molecular weight at the time of synthesizing the polymer block A ¹ was Mn 9,800, and the molecular weight at the time of synthesizing the polymer block A ¹ BA ¹ was Mn 108,200.

[Synthesis example 4]
MEA (421 g), HEA (21 g), BA (78 g), and ethyl acetate (770 g) were placed in a 4-necked flask with an internal volume of 3 L, and the mixed solution was thoroughly degassed by bubbling nitrogen gas and mixed. The internal temperature of the liquid was raised to 75°C, and 2,2'-azobis(2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., V-65) (0.35 g) was charged to initiate polymerization. After 5 hours, ethyl acetate was added so that the solid content was 30% by mass to obtain an ethyl acetate solution of an acrylic adhesive polymer (hereinafter also referred to as "polymer (Q-1)"). The obtained polymer (Q-1) had a Mn of 92,0000, a Mw/Mn of 8.72, and a Tg of -35°C.

[Synthesis example 5]
Polymer block A ¹ was synthesized in the same manner as in Synthesis Example 1, except that the RAFT agent, polymerization initiator, monomer, and type and amount of solvent used were changed as listed in Table 1, and the reaction was stopped. After that, the polymer block ^A1 was obtained by reprecipitation purification from methanol and vacuum drying. Next, the obtained polymer block A ¹ and the monomers and polymerization initiator shown in Table 1 are charged, and polymerization is carried out in the same manner as in Synthesis Example 1 to obtain an A ¹ BA ¹ type triblock copolymer. (hereinafter also referred to as "polymer (Q-2)") was obtained. The obtained triblock copolymer had Mn of 160,000 and Mw/Mn of 1.77. The molecular weight at the time of synthesis of the polymer block ^A1 was Mn 10,900.

[Synthesis example 6]
By performing the same operation as in Synthesis Example 5, except that the type and amount of the RAFT agent, polymerization initiator, monomer, and solvent used were changed as shown in Table 1, A ¹ BA ¹ type tritrium was prepared. An adhesive solution containing a block copolymer (hereinafter also referred to as "polymer (Q-3)") was obtained. The obtained triblock copolymer had Mn of 145,800 and Mw/Mn of 1.81. The molecular weight at the time of synthesis of polymer block ^A1 was Mn 20,800.

In addition, in Synthesis Examples 5 and 6, polymer block B was synthesized using polymer block A recovered by reprecipitation purification and drying, whereas in Synthesis Examples 1 and 2, polymer block B containing polymer block A was synthesized. Since polymer block B was synthesized using a polymer solution, in Table 1, "*" was written in the column of "polymer block A" under "synthesis of polymer block B." In Table 1, the notation "-" means that the compound was not used.

2. Preparation and evaluation of adhesive composition [Example 1]
An adhesive composition having a solid content concentration of 30% by mass of the polymer (P-1) obtained in Synthesis Example 1 above was placed on a polyethylene terephthalate (PET) separator with a thickness of 38 μm to form an adhesive layer after drying. The coating was applied to a thickness of 100 μm. Ethyl acetate was removed by drying the adhesive composition at 100° C. for 6 minutes. After drying, a PET separator having a thickness of 38 μm and having a different peeling force from the above separator was attached to obtain a pressure-sensitive adhesive film sample with a double-sided separator. Using the obtained adhesive film sample, evaluation was performed by the method shown below. The evaluation results are shown in Table 3. Table 3 also shows the composition ratio and physical properties of the polymer. Note that the numerical values listed in the monomer column of Table 3 represent the monomer composition [mol %] of the polymer. The monomer composition of the polymer was calculated from the amount charged and the amount of monomer consumed by GC measurement.

<Evaluation of peel strength at 23°C>
Two polyester fabrics were bonded together using an adhesive film sample cut into a width of 10 mm to obtain a laminate in which polyester fabric/adhesive film/polyester fabric were laminated in this order. The obtained laminate was compressed by hot press treatment (conditions: 130° C., 3 kg/cm ² , 10 seconds). The laminate after pressure bonding was used as a test piece, and the T-type peel strength [N /10mm] was measured.
<Evaluation of 80°C peel strength>
The T-shaped peel strength [N/10 mm] was measured in the same manner as in "Evaluation of 23°C peel strength" except that the measurement temperature for peel strength was changed from 23°C to 80°C.

[Examples 2 and 3 and Comparative Examples 1 to 3]
Various evaluations were performed in the same manner as in Example 1 using the adhesive compositions (solid content concentration 30% by mass) obtained in each of Synthesis Examples 2 to 6. The results are shown in Table 3.

As shown in Table 3, in Examples 1 to 3 using adhesive compositions containing the multi-block copolymer (P), the 80°C peel strength was as high as 3.3 N/10 mm or more. The peel strength at 23° C. also showed a high value of 11.3 N/10 mm or more. From these results, the adhesive compositions of Examples 1 to 3 showed that the fabrics were difficult to separate from each other both at high temperatures and at room temperature.

On the other hand, in Comparative Example 1 using the polymer (Q-1) consisting only of soft segments, both the 80°C peel strength and the 23°C peel strength were lower than those of Examples 1 to 3, and in particular, the 80°C peel strength was 0. The lowest value was 2N/mm. In addition, in Comparative Example 2 using Polymer (Q-1), which is a triblock copolymer, the 23°C peel strength was equivalent to Examples 1 to 3, but the 80°C peel strength was 1. It was as low as .2N/10mm, and the adhesive part was easy to peel off under high temperature conditions. In Comparative Example 3 using a triblock copolymer (polymer (Q-3)) having the same proportion of hard segments as in Example 2, both the 80°C peel strength and the 23°C peel strength were lower than those in Example 1. It was lower than 3.

From the above results, it is clear that an adhesive composition containing the multi-block copolymer (P) can provide an adhesive that exhibits high peel strength both under high temperature conditions and room temperature conditions. Ta.

Claims (10)

It has a polymer block A having a glass transition point of 50°C or higher, and a polymer block B having a glass transition point of 10°C or lower and mainly consisting of structural units derived from a (meth)acrylic monomer, and contains a multi-block copolymer in which the total number of the polymer block A and the polymer block B in one molecule is 4 or more,
The multi-block copolymer is an adhesive composition in which the ratio of the polymer block A to the total amount of the polymer block A and the polymer block B is 5 mol% or more and 40 mol% or less. The adhesive composition according to claim 1 , wherein the multi-block copolymer has three or more polymer blocks A in one molecule. The multi-block copolymer includes, as the polymer block A, a polymer block having at least one type selected from the group consisting of a structural unit derived from a styrene compound and a structural unit derived from an imide group-containing vinyl compound. , the pressure-sensitive adhesive composition according to claim 1 or 2 . The multi-block copolymer includes, as the polymer block A, a first polymer block and a second polymer block having a composition of constituent monomer units different from that of the first polymer block. , the adhesive composition according to any one of claims 1 to 3 . The first polymer block is a polymer block having a structural unit derived from a styrene compound,
The adhesive composition according to claim 4 , wherein the second polymer block is a polymer block having a structural unit derived from a (meth)acrylic monomer. The adhesive composition according to claim 4 or 5 , wherein the first polymer block and the second polymer block have a structural unit derived from an imide group-containing vinyl compound. Any one of claims 1 to 6 , wherein the polymer block B has a structural unit derived from at least one selected from the group consisting of an alkyl (meth)acrylate compound and an alkoxyalkyl (meth)acrylate compound. The adhesive composition described in . The adhesive composition according to any one of claims 1 to 7 , wherein the polymer block B has a structural unit derived from a hydroxyalkyl (meth)acrylate compound. The adhesive according to any one of claims 1 to 8 , wherein the multi-block copolymer is a pentablock copolymer in which the total number of the polymer blocks A and the polymer blocks B is five. agent composition. An adhesive product comprising a support and an adhesive layer formed on the support using the adhesive composition according to any one of claims 1 to 9 .