Composition, hot-melt pressure-sensitive adhesive, and laminate

Abstract

A composition comprising a block copolymer (A) and a tackifier (B), wherein the block copolymer (A) includes a block structural unit (a1) and a block structural unit (a2), the block structural unit (a1) includes, as a main component, a polyester unit (a1-1) including a unit derived from an aliphatic diol (a1-1-1) and an aliphatic dicarboxylic acid (a1-1-2), and the block structural unit (a2) includes, as a main component, a unit (a2-1) derived from at least one selected from the group consisting of hydroxy carboxylic acids and hydroxy carboxylic acid condensates.

Description

Composition, Hot-Melt Adhesive, and Laminate

[0001] The present invention relates to a composition, a hot-melt adhesive, and a laminate.

[0002] A hot-melt adhesive is an adhesive obtained by coating in a heated and melted state and then cooling. Since it does not use a solvent in the manufacturing process, it is a highly safe and environmentally friendly adhesive. Therefore, hot-melt adhesives are widely used in fields such as paper processing, woodworking, and electronics, and development is also actively carried out.

[0003] For example, Patent Document 1 describes an adhesive composition containing a urethane prepolymer having a hydroxyl group, which is a reaction product of a polyol, a polyfunctional polyol, and a polyisocyanate, which is a copolymer of a monomer mixture containing a monomer having a lactic acid unit and a monomer having at least one of a lactone unit and an aliphatic hydroxycarboxylic acid unit. Patent Document 2 describes that it can be used as a hot-melt adhesive by blending an adhesion promoter with a caprolactone-lactide copolymer. Patent Document 3 describes a hot-melt adhesive composition containing a polyester polymer selected from the group consisting of a polylactic acid-based polymer and a polyhydroxyalkanoic acid-based polymer and a polyester plasticizer.

[0004] JP 2021-169586 AWO 2019 / 059834 AWO 2022 / 073006

[0005] Conventionally, many compositions suitable for hot-melt adhesives have been reported, but there is a demand for a composition that is more excellent in the balance of adhesive strength, holding power, and tackiness when used as a hot-melt adhesive.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a composition excellent in the balance of adhesive strength, holding power, and tackiness, a hot-melt adhesive containing the composition, and a laminate containing the composition.

[0007] As a result of diligent research to solve the above problems, the inventors have conceived the present invention described below and found that it can solve the problems. That is, the present invention is as follows.

[0008] [1] A composition comprising a block copolymer (A) and a tackifier (B), wherein the block copolymer (A) comprises a block structural unit (a1) and a block structural unit (a2), the block structural unit (a1) mainly comprises a polyester unit (a1-1) containing units derived from an aliphatic diol (a1-1-1) and an aliphatic dicarboxylic acid (a1-1-2), and the block structural unit (a2) mainly comprises a unit (a2-1) derived from at least one selected from the group consisting of hydroxycarboxylic acids and hydroxycarboxylic acid condensates. [2] The composition according to [1] above, satisfying the following formulas (1) and (2). |Contact angle (x) - Contact angle (z)| ≤ 10° (1) |Contact angle (y) - Contact angle (z)| ≥ 5° (2) (In formulas (1) and (2), the contact angle (x) is the contact angle of the polymer consisting of the block structure unit (a1) with water, the contact angle (y) is the contact angle of the polymer consisting of the block structure unit (a2) with water, and the contact angle (z) is the contact angle of the tackifier (B) with water.) [3] The composition according to [1] or [2] above, wherein the number average molecular weight of the block copolymer (A) is greater than 10,000. [4] The composition according to any one of [1] to [3] above, wherein the block structure unit (a2) mainly consists of a polylactic acid unit (a2-1-1) containing a unit derived from at least one selected from the group consisting of lactic acid and lactic acid condensates. [5] The composition according to any one of [1] to [4] above, wherein the aliphatic diol (a1-1-1) has an alkyl group as a branched chain and the main chain has 3 or more carbon atoms. [6] The composition according to [5] above, wherein the branched chain is a methyl group. [7] The composition according to any one of [1] to [6] above, wherein the total number of carbon atoms of the aliphatic diol (a1-1-1) is 4 to 18. [8] The composition according to any one of [1] to [7] above, wherein the aliphatic diol (a1-1-1) is 3-methyl-1,5-pentanediol. [9] The composition according to any one of [1] to [8] above, wherein the total number of carbon atoms of the aliphatic dicarboxylic acid (a1-1-2) is 4 to 18.

[10] The composition according to any one of [1] to [9] above, wherein the melting point of the block copolymer (A) is 125°C or higher.

[11] The composition according to any one of [1] to

[10] , wherein the content of block structural units (a2) in the block copolymer (A) is 15 to 65% by mass.

[12] The composition according to any one of [1] to

[11] , comprising a plasticizer (C).

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

[12] .

[14] A laminate comprising the composition according to any one of [1] to

[12] .

[15] A laminate comprising the hot melt adhesive according to

[13] .

[0009] According to the present invention, it is possible to provide a composition having an excellent balance of adhesive strength, holding power, and tackiness, a hot melt adhesive containing the composition, and a laminate containing the composition.

[0010] The following description is based on an example of an embodiment of the present invention. However, the embodiments shown below are illustrative examples for realizing the technical concept of the present invention, and the present invention is not limited to the following description. In this specification, preferred forms of embodiments are shown, but combinations of two or more individual preferred forms are also preferred forms. When there are several numerical ranges for matters indicated by numerical ranges, a preferred form can be made by selectively combining their lower and upper limits. Also, when a numerical range is described as "XX to YY", it means "XX or more and YY or less". In this specification, "~ unit" (where "~" indicates a polymer) means "a unit derived from ~". For example, "polylactic acid unit" means "a unit derived from polylactic acid", and "polyester unit" means "a unit derived from polyester". In this specification, the "main chain" of an aliphatic diol means a straight chain that links two hydroxyl groups together. Also, "branched chain" means a molecular chain other than the main chain in a molecule. In this specification, the "main component" in a structural unit means the unit with the highest content (mass%) among the units that constitute the structural unit. The "main component" in a structural unit has a content of, for example, 50% by mass or more, 70% by mass or more in one embodiment, 80% by mass or more in another embodiment, 85% by mass or more in another embodiment, 90% by mass or more in another embodiment, and 100% by mass in another embodiment. In this specification, "solids" means the components excluding the solvent. The solids of a resin composition means the components of the resin composition excluding the solvent.

[0011] [Composition] The composition of this embodiment is a composition comprising a block copolymer (A) and a tackifier (B), wherein the block copolymer (A) comprises a block structural unit (a1) and a block structural unit (a2), the block structural unit (a1) mainly comprises a polyester unit (a1-1) containing units derived from an aliphatic diol (a1-1-1) and an aliphatic dicarboxylic acid (a1-1-2), and the block structural unit (a2) mainly comprises a unit (a2-1) derived from at least one selected from the group consisting of hydroxycarboxylic acids and hydroxycarboxylic acid condensates.

[0012] The composition of this embodiment exhibits an excellent balance of adhesiveness, holding power, and tackiness. Although the detailed reasons for this are unknown, it is presumed to be as follows. The composition of this embodiment includes a block copolymer (A) containing a block structure unit (a1) mainly composed of polyester units, a block structure unit (a2) mainly composed of a unit (a2-1) selected from the group consisting of hydroxycarboxylic acids and hydroxycarboxylic acid condensates, and a tackifier (B). With this configuration, the composition is presumed to have a good balance of adhesiveness derived from the wettability of the block structure unit (a1), holding power derived from the cohesive force of the block structure unit (a2), and tackiness derived from the tackifier (B). Furthermore, the composition of this embodiment has excellent adhesiveness, holding power, and tackiness even without containing a crosslinking agent, and can be reversibly softened, melted, and hardened repeatedly, making it suitable for use as a hot melt adhesive.

[0013] <Block Copolymer (A)> Block copolymer (A) contains block structural units (a1) and block structural units (a2). The inclusion of block structural units (a1) in block copolymer (A) that mainly consist of polyester units (a1-1) improves the adhesive strength of the composition. Furthermore, the inclusion of block structural units (a2) in block copolymer (A) that mainly consist of units (a2-1) derived from at least one selected from the group consisting of hydroxycarboxylic acids and hydroxycarboxylic acid condensates improves the holding power of the composition.

[0014] From the viewpoint of obtaining a composition with an excellent balance of adhesiveness, holding power, and tackiness, it is preferable that the block copolymer (A) satisfies the following formulas (1) and (2): |Contact angle (x) - Contact angle (z)| ≤ 10° (1) |Contact angle (y) - Contact angle (z)| ≥ 5° (2) In formulas (1) and (2), the contact angle (x) is the contact angle of the polymer consisting of block structural units (a1) with water, the contact angle (y) is the contact angle of the polymer consisting of block structural units (a2) with water, and the contact angle (z) is the contact angle of the tackifier (B) described later with water. From the viewpoint of compatibility between the block structural units (a1) and the tackifier (B), |Contact angle (x) - Contact angle (z)| is preferably 10° or less, more preferably 8° or less, even more preferably 5° or less, even more preferably 3° or less, even more preferably 1° or less, and may be 0°. The contact angle (y) - contact angle (z) is preferable as the numerical value increases from the viewpoint of maintaining the crystallinity of the block structure unit (a2). For example, it may be 5° or more, 8° or more, or 10° or more. The contact angle (x), contact angle (y), and contact angle (z) were measured in accordance with the static drop method of JIS R3257:1999. Specifically, ion-exchanged water was dropped onto sheets obtained by molding each component under the molding conditions described below, and the contact angle with water was measured under the following contact angle measurement conditions. More specifically, it can be measured by the method described in the examples. <Molding Conditions> The component to be measured (polymer consisting of block structural units (a1), polymer consisting of block structural units (a2), or tackifier (B)) is sandwiched between a 50 μm thick polyester film and a 50 μm thick release polyester film. Using a vacuum heat press device "IMC-183B" (manufactured by Imoto Seisakusho Co., Ltd.), the pressure is reduced to -0.1 MPaG using an oil rotary pump. For components with a softening point below 25°C, the press is applied at 25°C, and for components with a softening point of 25°C or higher, the press is applied at 80 kN for 1 minute at a temperature approximately 20 to 30°C higher than the softening point or melting point. Subsequently, the press is applied at 8 MPaG for 1 minute using a cooling press device equipped with water flow cooling to form a sheet with a thickness of 50 μm.The softening point is a value obtained by measurement in accordance with JIS K6863:1994, and the melting point is a value obtained by measurement in accordance with JIS K7121:2012. <Contact angle measurement conditions> Measuring device: OCA20 (manufactured by Eiko Seiki Co., Ltd.) Temperature: 23℃ Solvent: Ion-exchanged water droplet quantity: 2.0 μL Measurement time: Within 5 seconds after dropping.

[0015] From the viewpoint of suitability as a hot-melt adhesive that can be reversibly softened, melted, and hardened repeatedly, it is preferable that the block copolymer (A) does not contain units derived from the isocyanate component.

[0016] ≪Block Structure Unit (a1)≫ The block structure unit (a1) mainly contains polyester units (a1-1) which contain units derived from aliphatic diols (a1-1-1) and aliphatic dicarboxylic acids (a1-1-2).

[0017] The content of block structural units (a1) in block copolymer (A) is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 55% by mass or more, and even more preferably 60% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, even more preferably 77% by mass or less, and even more preferably 75% by mass or less. That is, the content of block structural units (a2) in block copolymer (A) is preferably 40 to 85% by mass, more preferably 50 to 80% by mass, even more preferably 55 to 77% by mass, and even more preferably 60 to 75% by mass. If the content of block structural units (a1) in block copolymer (A) is 35% by mass or more, the adhesive strength of the composition tends to be better. Also, if the content of block structural units (a1) in block copolymer (A) is 85% by mass or less, the holding power of the composition tends to be better.

[0018] <Polyester Units (a1-1)> The content of polyester units (a1-1) in the block structure unit (a1) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass. Furthermore, there is no upper limit on the amount of polyester units (a1-1) contained in the block structure unit (a1), for example, it may be 100% by mass or less.

[0019] The polyester unit (a1-1) may or may not contain units derived from monomers other than the aliphatic diol (a1-1-1) and the aliphatic dicarboxylic acid (a1-1-2). The monomers other than the aliphatic diol (a1-1-1) and the aliphatic dicarboxylic acid (a1-1-2) are not particularly limited as long as they do not impair the effects of the present invention. The total amount of aliphatic diol (a1-1-1) and aliphatic dicarboxylic acid (a1-1-2) in the polyester unit (a1-1) is preferably 90 mol% or more, more preferably 95 mol% or more, even more preferably 99 mol% or more, and may be 100 mol%.

[0020] (Aliphatic diol (a1-1-1)) The carbon number of the main chain of aliphatic diol (a1-1-1) is preferably 3 or more, more preferably 4 or more, from the viewpoint of exhibiting better adhesiveness, and preferably 8 or less, even more preferably 7 or less, from the viewpoint of exhibiting better biodegradability. That is, the carbon number of the main chain of aliphatic diol (a1-1-1) is preferably 3 to 8, more preferably 4 to 7. The total carbon number of aliphatic diol (a1-1-1) is preferably 4 or more, more preferably 5 or more, from the viewpoint of exhibiting better adhesiveness, and preferably 18 or less, more preferably 12 or less, even more preferably 9 or less, from the viewpoint of exhibiting better biodegradability. That is, the total carbon number of aliphatic diol (a1-1-1) is preferably 4 to 18, more preferably 5 to 12, even more preferably 5 to 9. In this specification, "total carbon number" means the carbon number of the main chain when there is no branched chain, and the sum of the carbon number of the main chain and the carbon number of the branched chain when there is a branched chain.

[0021] Aliphatic diols (a1-1-1) preferably have alkyl groups as branched chains, from the viewpoint of suppressing crystallization of block structural units (a1) and exhibiting superior biodegradability, as well as superior adhesiveness. When aliphatic diols (a1-1-1) have alkyl group branched chains, the block structural units (a1) tend to become amorphous polymers, so it is presumed that during biodegradation, microorganisms can more easily penetrate the polymer structure, resulting in superior biodegradability. However, being an amorphous polymer is only one factor that affects biodegradability. This is because biodegradation is thought to occur through a combination of various factors, such as whether microorganisms recognize the amorphous structure as food, whether enzymes and microorganisms can easily approach it, steric hindrance of branched chains, melting point, and crystallinity. Therefore, it is not the case that biodegradability is obtained simply because a polymer is amorphous.

[0022] In aliphatic diol (a1-1-1), the number of branched chains is preferably one or two, more preferably one. The branched chains are preferably a methyl group, an ethyl group, and a propyl group, more preferably a methyl group and an ethyl group, and even more preferably a methyl group. If aliphatic diol (a1-1-1) has multiple branched chains, each branched chain may be the same or different. From the viewpoint of readily reacting with dicarboxylic acids and easily producing triblock copolymers, it is preferable that the branched chains of aliphatic diol (a1-1-1) are located at least γ-position away from the hydroxyl group and are methyl groups with low steric hindrance. Furthermore, from the viewpoint of superior biodegradability, it is preferable that aliphatic diol (a1-1-1) has hydroxyl groups at both ends of the main chain.

[0023] From the viewpoint of exhibiting superior biodegradability and superior adhesive strength, it is preferable that the aliphatic diol (a1-1-1) has an alkyl group as a branched chain and the main chain has 3 or more carbon atoms.

[0024] Examples of aliphatic diols (a1-1-1) include 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, 1,2-pentanediol, 1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 1,4-pentanediol, and 2-methyl-2,4-pentanediol. Examples include 1,5-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 2-ethyl-1,6-hexanediol, and 2-methyl-1,8-octanediol. The aliphatic diol (a1-1-1) is preferably 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, and 2,4-diethyl-1,5-pentanediol, and more preferably 3-methyl-1,5-pentanediol. Aliphatic diols (a1-1-1) may be used individually or in combination of two or more types.

[0025] (Aliphatic dicarboxylic acid (a1-1-2)) The total number of carbon atoms in aliphatic dicarboxylic acid (a1-1-2) is preferably 4 or more from the viewpoint of exhibiting better adhesiveness, and preferably 18 or less, more preferably 12 or less, and even more preferably 8 or less from the viewpoint of exhibiting better biodegradability. That is, the total number of carbon atoms in aliphatic dicarboxylic acid (a1-1-2) is preferably 4 to 18, more preferably 4 to 12, and even more preferably 4 to 8.

[0026] Examples of aliphatic dicarboxylic acids (a1-1-2) include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonamethylenedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, heptadecanedioic acid, octadecanedicarboxylic acid, and the like. The aliphatic dicarboxylic acid (a1-1-2) is preferably succinic acid, adipic acid, and sebacic acid, and more preferably adipic acid. The aliphatic dicarboxylic acid (a1-1-2) may be used alone or in combination of two or more types.

[0027] (Preferred combination of aliphatic diol (a1-1-1) and aliphatic dicarboxylic acid (a1-1-2)) From the viewpoint of obtaining a composition with an excellent balance of adhesiveness, holding power, and tackiness, the preferred combination of aliphatic diol (a1-1-1) and aliphatic dicarboxylic acid (a1-1-2) is 3-methyl-1,5-pentanediol and adipic acid.

[0028] (Ratio of aliphatic diol (a1-1-1) to aliphatic dicarboxylic acid (a1-1-2)) The molar ratio of the charges when reacting aliphatic diol (a1-1-1) and aliphatic dicarboxylic acid (a1-1-2) [aliphatic diol (a1-1-1) / aliphatic dicarboxylic acid (a1-1-2)] is preferably 1.4 / 1 to 1 / 1.4, more preferably 1.2 / 1 to 1 / 1.2.

[0029] <Units other than polyester units (a1-1) (a1-2)> The block structure unit (a1) may contain units other than polyester units (a1-1) (a1-2). The monomers constituting the unit (a1-2) are not particularly limited as long as they do not impair the effects of the present invention. The content ratio of units (a1-2) in the block structure unit (a1) is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less, and may be 0% by mass.

[0030] <Number-average molecular weight of block structural unit (a1)> From the viewpoint of exhibiting superior adhesive strength, the number-average molecular weight of block structural unit (a1) is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 15,000 or more, and even more preferably 20,000 or more. From the viewpoint of exhibiting superior hot-melt coating properties, it is preferably 100,000 or less, more preferably 90,000 or less, even more preferably 80,000 or less, and even more preferably 70,000 or less. That is, the number-average molecular weight of block structural unit (a1) is preferably 5,000 to 100,000, more preferably 10,000 to 90,000, even more preferably 15,000 to 80,000, and even more preferably 20,000 to 70,000. The number-average molecular weight of block structural unit (a1) can be determined by gel permeation chromatography (GPC), and specifically can be measured by the method described in the examples.

[0031] ≪Block Structural Unit (a2)≫ The block structural unit (a2) mainly contains a unit (a2-1) (hereinafter also simply referred to as "unit (a2-1)") derived from at least one selected from the group consisting of hydroxycarboxylic acids and hydroxycarboxylic acid condensates.

[0032] The content of block structural units (a2) in the block copolymer (A) is preferably 15% by mass or more, more preferably 20% by mass or more, even more preferably 23% by mass or more, and even more preferably 25% by mass or more, preferably 60% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and even more preferably 40% by mass or less. That is, the content of block structural units (a2) in the block copolymer (A) is preferably 15 to 60% by mass, more preferably 20 to 50% by mass, even more preferably 23 to 45% by mass, and even more preferably 25 to 40% by mass. If the content of block structural units (a2) in the block copolymer (A) is 15% by mass or more, the composition tends to have better retention strength. Also, if the content of block structural units (a2) in the block copolymer (A) is 65% by mass or less, the composition tends to have better adhesive strength.

[0033] <Unit (a2-1)> The content of unit (a2-1) in the block structure unit (a2) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass. Furthermore, there is no upper limit on the amount of unit (a2-1) contained in the block structure unit (a2), for example, it may be 100% by mass or less.

[0034] The unit (a2-1) may or may not contain units derived from monomers other than hydroxycarboxylic acids and hydroxycarboxylic acid condensates. The monomers other than hydroxycarboxylic acids and hydroxycarboxylic acid condensates are not particularly limited as long as they do not impair the effects of the present invention. The total amount of units derived from hydroxycarboxylic acids and hydroxycarboxylic acid condensates in unit (a2-1) is preferably 90 mol% or more, more preferably 95 mol% or more, even more preferably 99 mol% or more, and may be 100 mol%.

[0035] Examples of hydroxycarboxylic acids include aliphatic hydroxycarboxylic acids, alicyclic hydroxycarboxylic acids, and aromatic hydroxycarboxylic acids. Examples of aliphatic hydroxycarboxylic acids include 10-hydroxyoctadecanoic acid, lactic acid, hydroxyacrylic acid, 2-hydroxy-2-methylpropionic acid, and hydroxybutyric acid. Examples of alicyclic hydroxycarboxylic acids include hydroxymethylcyclohexanecarboxylic acid, hydroxymethylnorbornenecarboxylic acid, and hydroxymethyltricyclodecanoic acid. Examples of aromatic hydroxycarboxylic acids include hydroxybenzoic acid, hydroxytoluic acid, hydroxynaphthic acid, 3-(hydroxyphenyl)propionic acid, hydroxyphenylacetic acid, and 3-hydroxy-3-phenylpropionic acid. Examples of hydroxycarboxylic acid condensates include condensates of the above hydroxycarboxylic acids. Among these, lactic acid and lactic acid condensates are preferred from the viewpoint of obtaining a composition with a superior balance of adhesiveness, retention, and tackiness. In other words, the block structural unit (a2) preferably contains as its main component a polylactic acid unit (a2-1-1) which contains a unit derived from at least one selected from the group consisting of lactic acid and lactic acid condensates.

[0036] <Units other than unit (a2-1) (a2-2)> The block structure unit (a2) may contain units other than unit (a2-1) (a2-2). The monomers constituting unit (a2-2) are not particularly limited as long as they do not impair the effects of the present invention. The content ratio of unit (a2-2) in the block structure unit (a2) is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less, and may be 0% by mass.

[0037] <Polylactic acid units (a2-1-1)> The content of polylactic acid units (a2-1-1) in the block structure unit (a2) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 85% by mass or more, and even more preferably 90% by mass or more, and may be 100% by mass. Furthermore, there is no upper limit on the amount of polylactic acid units (a2-1-1) contained in the block structure unit (a2), for example, it may be 100% by mass or less.

[0038] The polylactic acid constituting the polylactic acid unit (a2-1-1) may be prepared by direct condensation of lactic acid, or by ring-opening polymerization of lactic acid condensates such as lactide. As the lactic acid, for example, at least one selected from the group consisting of L-lactic acid, D-lactic acid, and DL-lactic acid can be used. As the lactide, for example, at least one selected from the group consisting of L-lactide, D-lactide, DL-lactide, and meso-lactide can be used. Furthermore, the polylactic acid can be poly-L-lactic acid, poly-D-lactic acid, poly-DL-lactic acid, or stereocomplex polylactic acid obtained by mixing poly-L-lactic acid and poly-D-lactic acid. From the viewpoint of cost, availability of raw materials, and handling of the block copolymer (a2), poly-L-lactic acid, poly-D-lactic acid, and poly-DL-lactic acid are preferred, and poly-L-lactic acid and poly-D-lactic acid are more preferred. On the other hand, from the viewpoint of the cost and complexity of synthesis, it is preferable that the polylactic acid is not a stereocomplex polylactic acid. From the viewpoint of exhibiting better biodegradability, the block structural unit (a2) preferably contains 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, of structural units derived from poly-L-lactic acid or poly-D-lactic acid. For example, one preferred embodiment is that the block structural unit (a2) consists of structural units derived from poly-L-lactic acid or poly-D-lactic acid, that is, 100% by mass of structural units derived from poly-L-lactic acid or poly-D-lactic acid.

[0039] <Number-average molecular weight of block structural units (a2)> From the viewpoint of exhibiting superior retention, the number-average molecular weight of block structural units (a2) is preferably 1,000 or more, more preferably 5,000 or more, even more preferably 10,000 or more, and even more preferably 12,500 or more. From the viewpoint of exhibiting superior hot-melt coating properties, it is preferably 200,000 or less, more preferably 160,000 or less, even more preferably 120,000 or less, and even more preferably 100,000 or less. That is, the number-average molecular weight of block structural units (a1) is preferably 1,000 to 200,000, more preferably 5,000 to 160,000, even more preferably 10,000 to 120,000, and even more preferably 12,500 to 100,000. Note that when the block copolymer (A) has multiple block structural units (a2), the number-average molecular weight of block structural units (a2) means the sum of all blocks. The number-average molecular weight of the block structural unit (a2) can be determined from the number-average molecular weight of the block copolymer (A), described later, and the mass content of the block structural unit (a2).

[0040] <Structural unit ratio (mass ratio) of block structural unit (a1) and block structural unit (a2)> With respect to a total of 100 mass% of block structural unit (a1) and block structural unit (a2), block structural unit (a2) is preferably 15 mass% or more, more preferably 20 mass% or more, even more preferably 23 mass% or more, and even more preferably 25 mass% or more. Also, with respect to a total of 100 mass% of block structural unit (a1) and block structural unit (a2), block structural unit (a2) is preferably 60 mass% or less, more preferably 50 mass% or less, even more preferably 45 mass% or less, and even more preferably 40 mass% or less. That is, with respect to a total of 100 mass% of block structural unit (a1) and block structural unit (a2), block structural unit (a2) is preferably 15 to 60 mass%, more preferably 20 to 50 mass%, even more preferably 23 to 45 mass%, and even more preferably 25 to 40 mass%. If the proportion of the above block structure unit (a2) is 15% by mass or more, the composition tends to have better holding power. Also, if the proportion of the above block structure unit (a2) is 65% by mass or less, the composition tends to have better adhesive power. The mass ratio of block structure unit (a1) and block structure unit (a2) is: １ It can be determined by H-NMR, and specifically by the method described in the examples.

[0041] <<Number-average molecular weight of block copolymer (A)>>From the viewpoint of exhibiting more excellent adhesive strength, holding power, and peelability, the number-average molecular weight of the block copolymer (A) is preferably more than 10,000, more preferably 30,000 or more, still more preferably 40,000 or more, and even more preferably 50,000 or more. From the viewpoint of productivity, it is preferably 300,000 or less, more preferably 240,000 or less, still more preferably 180,000 or less, and even more preferably 150,000 or less. That is, the number-average molecular weight of the block copolymer (A) is preferably more than 10,000 and 300,000 or less, more preferably 30,000 to 240,000, still more preferably 40,000 to 180,000, and even more preferably 50,000 to 150,000. The number-average molecular weight of the block copolymer (A) can be determined by gel permeation chromatography (GPC), and specifically, it can be measured by the method described in the examples.

[0042] <<Bonding form of block copolymer (A)>>The bonding form of the block copolymer (A) is preferably a triblock type and a diblock type, and more preferably a triblock type. The block copolymer (A) may be a mixture of a triblock type and a diblock type. Specifically, the bonding form is preferably [block structural unit (a2)] - [block structural unit (a1)] - [block structural unit (a2)].

[0043] <<Glass transition temperature of block copolymer (A)>>From the viewpoint of exhibiting more excellent adhesive force and holding force, the glass transition temperature of the block copolymer (A) is preferably -40°C or lower, more preferably -45°C or lower, still more preferably -50°C or lower. Although the lower limit of the glass transition temperature of the block copolymer (A) is preferably lower, for example, it may be -80°C or higher, -70°C or higher, or -65°C or higher. That is, the glass transition temperature of the block copolymer (A) is preferably -80 to -40°C, more preferably -70 to -45°C, still more preferably -65 to -50°C. The glass transition temperature of the block copolymer (A) is a value obtained by measuring in accordance with JIS K7121:2012 and can be determined by a differential scanning calorimeter.

[0044] <<Melting point of block copolymer (A)>>From the viewpoint of more excellent holding force at high temperatures, the melting point of the block copolymer (A) is preferably 125°C or higher, more preferably 135°C or higher, still more preferably 140°C or higher, and even more preferably 145°C or higher. From the viewpoint of more excellent hot melt coating properties, it is preferably 180°C or lower, more preferably 175°C or lower, still more preferably 170°C or lower, and even more preferably 165°C or lower. That is, the melting point of the block copolymer (A) is preferably 125 to 180°C, more preferably 135 to 175°C, still more preferably 140 to 170°C, and even more preferably 145 to 165°C. The melting point of the block copolymer (A) is a value obtained by measuring in accordance with JIS K7121:2012 and can be determined by a differential scanning calorimeter.

[0045] <Method for Producing Block Copolymer (A)> A known method can be used to produce block copolymer (A). A known method for producing block copolymer (A) may be, for example, a method in which a polyester constituting the polyester unit (a1-1) is synthesized, and the polyester is polymerized with at least one selected from the group consisting of hydroxycarboxylic acid and hydroxycarboxylic acid condensates. The above polyester can be synthesized by a known method. For example, a polyester can be synthesized by reacting an aliphatic diol (a1-1-1) and an aliphatic dicarboxylic acid (a1-1-2) using an esterification catalyst (e.g., tin octoate, tin chloride, tin oxide). When polymerizing the polyester with at least one selected from the group consisting of hydroxycarboxylic acid and hydroxycarboxylic acid condensates, it is preferable to use a ring-opening polymerization catalyst (e.g., tin octoate, tin chloride, tin oxide). Examples of polymerization reactions include solution polymerization, melt polymerization, and interfacial polycondensation, and known polymerization reaction conditions can be set for all of these.

[0046] Another known method for producing the block copolymer (A) is, for example, to synthesize a polymer constituting a unit (a2-1) derived from at least one selected from the group consisting of hydroxycarboxylic acids and hydroxycarboxylic acid condensates, and a polyester constituting a polyester unit (a1-1), and then to react the polymer and the polyester. When the block structural unit (a2) is a polylactic acid unit (a2-1-1) containing a unit derived from at least one selected from the group consisting of lactic acid and lactic acid condensates, the polylactic acid constituting the polylactic acid unit (a2-1-1) can be synthesized by known methods. For example, polylactic acid may be synthesized by directly reacting lactic acid by a condensation method, or polylactic acid may be synthesized by reacting lactide by a ring-opening polymerization method. When polymerizing polylactic acid and polyester, it is preferable to use an esterification catalyst (for example, tin octylate, tin chloride, tin oxide, etc.). Polymerization reactions include solution polymerization, melt polymerization, interfacial polycondensation, etc., and known polymerization reaction conditions can be set for all of them.

[0047] <Tackifier (B)> The composition of this embodiment includes a tackifier (B). The inclusion of tackifier (B) gives the composition excellent tackiness and adhesiveness. In this specification, tackifier (B) is an oligomer that is not included in the block copolymer (A), can impart tackiness when added, has a softening point of 25°C or higher, and has a number average molecular weight of 10,000 or less. The softening point of tackifier (B) is a value obtained by measurement in accordance with JIS K6863:1994.

[0048] The softening point of the tackifier (B) is preferably 40 to 200°C, more preferably 50 to 170°C, and even more preferably 60 to 150°C, from the viewpoint of exhibiting superior adhesive strength and holding power.

[0049] Examples of tackifiers (B) include rosin-based tackifying resins, terpene-based tackifying resins, hydrocarbon-based tackifying resins, styrene-based tackifying resins, and acrylic-based tackifying resins. Among these, rosin-based tackifying resins, terpene-based tackifying resins, and hydrocarbon-based tackifying resins are preferred from the viewpoint of further improving adhesive strength, and alicyclic saturated hydrocarbon-based tackifying resins are more preferred. Tackifiers (B) may be used alone or in combination of two or more types.

[0050] Examples of rosin-based tackifying resins include unmodified rosin (raw rosin) such as gum rosin, wood rosin, and tall oil rosin; modified rosin obtained by hydrogenation, disproportionation, polymerization, etc. (hydrogenated rosin, disproportionated rosin, polymerized rosin, and other chemically modified rosin; the same applies hereinafter); and various other rosin derivatives. Examples of the above rosin derivatives include rosin esters such as those obtained by esterifying unmodified rosin with alcohols (i.e., rosin esters) and modified rosin with alcohols (i.e., modified rosin esters); unsaturated fatty acid modified rosins obtained by modifying unmodified rosin or modified rosin with unsaturated fatty acids; unsaturated fatty acid modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing the carboxyl groups in unmodified rosin, modified rosin, unsaturated fatty acid modified rosins, or unsaturated fatty acid modified rosin esters; metal salts of rosins (especially rosin esters) such as unmodified rosin, modified rosin, and various rosin derivatives; and rosinphenol resins obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and then thermal polymerization. Among these, rosin ester-based tackifiers are preferred.

[0051] Examples of terpene-based tackifying resins include terpene resins such as α-pinene polymers, β-pinene polymers, and dipentene polymers; and modified terpene resins obtained by modifying these terpene resins (phenol modification, aromatic modification, hydrogenation modification, hydrocarbon modification, etc.). Examples of the above modified terpene resins include terpene phenol resins, aromatically modified terpene resins (e.g., styrene terpene resins), and hydrogenated terpene resins. Among these, aromatically modified terpene resins are preferred. From the above terpene-based tackifying resins (e.g., aromatically modified terpene resins), one or more types with different characteristics (e.g., softening point) may be used in combination. Among these, terpene phenol resins are preferred.

[0052] Examples of hydrocarbon-based tackifying resins include aliphatic (C5) petroleum resins, aromatic (C9) petroleum resins, aliphatic / aromatic copolymer (C5 / C9) petroleum resins, hydrogenated versions thereof (for example, alicyclic petroleum resins obtained by hydrogenating aromatic petroleum resins (alicyclic saturated hydrocarbon resins)), various modified versions thereof (for example, maleic anhydride modified versions), coumarone resins, indencoumarone resins, and various other hydrocarbon-based resins. Among these, indencoumarone resins are preferred. Hydrocarbon-based tackifying resins may be used alone or in combination of two or more types.

[0053] Examples of styrene-based tackifying resins include styrene homopolymers, α-methylstyrene homopolymers, α-methylstyrene / styrene copolymers, styrene / aliphatic copolymers, α-methylstyrene / styrene / aliphatic copolymers, C9 petroleum resins, C5 / C9 petroleum resins, phenol-modified styrene resins, and hydrogenated versions thereof. Styrene-based tackifying resins may be used individually or in combination of two or more types.

[0054] Examples of acrylic tackifying resins include acrylic tackifying resins based on acrylic polymers (homopolymers or copolymers) that use one or more alkyl (meth)acrylate esters as monomer components. Specific examples of alkyl (meth)acrylate esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and (meth) Examples of C1-20 alkyl esters of (meth)acrylate include nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. The above acrylic polymer may optionally contain units corresponding to other monomer components copolymerizable with the above alkyl (meth)acrylate.

[0055] <Plasticizer (C)> From the viewpoint of providing a composition with excellent handling properties, the composition may or may not contain a plasticizer (C). In this specification, plasticizer (C) is a compound other than block copolymer (A) that has a softening point of less than 25°C and causes a decrease in melt viscosity and storage modulus when added. The softening point of plasticizer (C) is a value obtained by measurement in accordance with JIS K6863:1994. The plasticizer (C) is preferably biodegradable in any of the following environments: industrial compost, household compost, soil, or marine. For example, aliphatic polyesters, plant esters such as rapeseed oil and castor oil, triacetin, synthetic esters such as diethyl phthalate and triethyl citrate, polyols such as ethylene glycol and trimethylolpropane, and their derivatives, and sugars such as sorbitol are examples of suitable plasticizers. These may be used individually or in combination of two or more. The amount of plasticizer (C) in the composition can be determined appropriately depending on the application.

[0056] <Other Components in the Composition> The composition may or may not contain other components besides the block copolymer (A), tackifier (B), and plasticizer (C). Examples of other components include polymers other than the block copolymer (A), softeners, antioxidants, inorganic fillers, lubricants, light stabilizers, processing aids, colorants such as pigments and dyes, flame retardants, antistatic agents, matting agents, silicone oils, antiblocking agents, UV absorbers, mold release agents, foaming agents, antibacterial agents, antifungal agents, fragrances, etc. These other components may be used individually or in combination of two or more. The content of other components in the composition is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

[0057] <Content of each component in the composition> From the viewpoint of exhibiting better adhesiveness and holding power, the content of block copolymer (A) in the composition is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, and from the viewpoint of exhibiting better tackiness, it is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. That is, the content of block copolymer (A) in the composition is preferably 15 to 80% by mass, more preferably 20 to 75% by mass, and even more preferably 25 to 70% by mass.

[0058] The content of the tackifier (B) in the composition is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoint of exhibiting better tackiness, and preferably 60% by mass or less, more preferably 55% by mass or less, and even more preferably 50% by mass or less, from the viewpoint of exhibiting better adhesive strength and holding power. That is, the content of the tackifier (B) in the composition is preferably 15 to 60% by mass, more preferably 20 to 55% by mass, and even more preferably 25 to 50% by mass.

[0059] When the composition contains a plasticizer (C), the content of the plasticizer (C) in the composition is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of improving handling properties, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, from the viewpoint of obtaining the effects of the present invention more efficiently. That is, the content of the plasticizer (C) in the composition is preferably 5 to 50% by mass, more preferably 8 to 40% by mass, and even more preferably 10 to 35% by mass.

[0060] [Method for Producing the Composition] The method for producing the composition is not limited as long as the effects of the present invention are achieved. For example, it can be produced by mixing a block copolymer (A), a tackifier (B), and a plasticizer (C) which may be added as needed, using a known mixing or kneading device such as a kneader-ruder, extruder, mixing roll, or Banbury mixer. Alternatively, it may be produced by dissolving each component in an organic solvent, mixing them, and then distilling off the organic solvent. Examples of organic solvents include chloroform, toluene, ethyl acetate, ethylbenzene, methylene chloride, tetrahydrofuran, methyl ethyl ketone, dimethyl sulfoxide, and a toluene-ethanol mixed solvent. Among these, chloroform is preferred.

[0061] [Hot Melt Adhesive] The composition of this embodiment can be used as a hot melt adhesive. The hot melt adhesive of this embodiment can also be used in the form of an adhesive sheet made of the hot melt adhesive, an adhesive layer containing the hot melt adhesive, or a laminate (for example, a laminated film or laminated sheet) containing the adhesive layer. That is, according to the present invention, it is possible to provide an adhesive sheet made of the above composition, an adhesive layer containing the above composition, and a laminate containing the above composition.

[0062] The hot-melt adhesive of this embodiment can be used after heating and melting, or it may be dissolved in a solvent and used as a solution-type adhesive. When the hot-melt adhesive of this embodiment is used after heating and melting, for example, it can be formed into a sheet or film shape using a hot-melt coating method, T-die method, inflation method, calendering method, lamination method, press molding method, etc. When the hot-melt adhesive of this embodiment is used after dissolving it in a solvent, for example, a heat-resistant material such as polyethylene terephthalate or a flat plate or roll such as a steel belt can be used as a support, and a solution of the hot-melt adhesive dissolved in a solvent can be coated onto these using a bar coater, roll coater, die coater, comma coater, etc., and the solvent can be removed by drying (solution casting method) to form the adhesive layer.

[0063] The hot-melt adhesive of this embodiment can be used for a variety of applications. Furthermore, the adhesive layer containing the hot-melt adhesive can be used as an adhesive sheet on its own, and the laminate containing the hot-melt adhesive can also be applied to a variety of applications. Examples include adhesives, adhesive tapes, films, or sheets for surface protection, masking, bundling, packaging, office use, labeling, decoration / display, joining, dicing tape, sealing, corrosion and waterproofing, medical and sanitary use, glass shatter prevention, electrical insulation, holding and fixing electronic equipment, semiconductor manufacturing, optical display films, adhesive optical films, electromagnetic shielding, or sealing materials for electrical and electronic components.

[0064] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0065] The compounds used in the examples and comparative examples are as follows: • Poly((3-methyl-1,5-pentanediol)-alt-(adipic acid)): "Kuraray Polyol P-6010" (manufactured by Kuraray Co., Ltd.) • Adipic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) • Tin octoate (manufactured by Tokyo Chemical Industry Co., Ltd.) • Toluene (manufactured by Kishida Chemical Co., Ltd.) • L-lactide (manufactured by Tokyo Chemical Industry Co., Ltd.) • Methanol (manufactured by Fujifilm Wako Pure Chemical Industries Ltd.) • 2-methyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) • Potassium titanium oxalate dihydrate (manufactured by Kanto Chemical Co., Ltd.) • Tackifier 1: Phenolic modified indencumarone resin "Novares® CA 100" (manufactured by Rain Carbon Inc.) • Tackifier 2: Rosin ester "Polimelt P88" (manufactured by Respol Resinas) • Tackifier 3: Terpene phenol resin "YS Polystar N125" (manufactured by Yasuhara Chemical Co., Ltd.) • Tackifier 4: Hydrogenated petroleum resin "Alcon P-100" (manufactured by Arakawa Chemical Industries, Ltd.) • Tackifier 5: Rosin ester "Pine Crystal D-6011" (manufactured by Arakawa Chemical Industries, Ltd.) • Tackifier 6: Rosin ester "Pine Crystal D-6021" (manufactured by Arakawa Chemical Industries, Ltd.) • Plasticizer 1: Poly((3-methyl-1,5-pentanediol)-alt-(adipic acid)) "Kuraray Polyol P-6010" (manufactured by Kuraray Co., Ltd.)

[0066] The physical properties of the block copolymer (A), polymer, and composition in the examples and comparative examples were measured or evaluated by the following methods.

[0067] (1) Weight-average molecular weight (Mw) and number-average molecular weight (Mn) of block copolymers and polymers were determined by gel permeation chromatography (GPC) on a standard polystyrene basis, with weight-average molecular weight (Mw) and number-average molecular weight (Mn) being calculated. <GPC measurement conditions> Apparatus: GPC apparatus "HLC-8220" manufactured by Tosoh Corporation Separation column: "TSKgel SuperMultiporeHZ-M" manufactured by Tosoh Corporation (column diameter = 4.6 mm, column length = 15 cm) (two columns connected in series) Eluent: Tetrahydrofuran (THF) Eluent flow rate: 0.35 mL / min Column temperature: 40°C Detection method: Differential refractive index (RI) Injection volume: 10 μL Concentration: 1 mg / 1 mL (block copolymer or polymer / THF)

[0068] (2) Mass ratio (block structural unit (a1):block structural unit (a2)) １ The mass ratio (block structure unit (a1):block structure unit (a2)) between block structure unit (a1) and block structure unit (a2) was calculated using H-NMR. That is, １ The molar ratio of block structure unit (a1) was calculated from the area ratio of the signal around 0.9 ppm originating from block structure unit (a1), which is mainly composed of polyester units (a1), and the signal around 5.2 ppm originating from block structure unit (a2) (polylactic acid units) in the spectrum obtained by H-NMR. The mass ratio was obtained by multiplying this molar ratio by the molecular weight of the block structure unit, and the mass ratio of block structure unit (a2) when the sum of these mass ratios was adjusted to 100 was defined as the hard ratio. １ ¹H-NMR Measurement Conditions: Equipment: JEOL Ltd. Nuclear Magnetic Resonance Spectrometer "JNM-ECX400" Solvent: Deuterated chloroform Measurement Temperature: 50°C Number of Accumulations: 1024 Measurement Conditions: Heating Rate 10°C / min

[0069] (3) Glass transition temperature and melting point The glass transition temperature and melting point were measured using a differential scanning calorimeter in accordance with JIS K7121:2012. In this specification, the glass transition temperature is defined as the midpoint glass transition temperature in JIS K7121:2012, and the melting peak temperature is defined as the melting point. Specifically, under the following measurement conditions 2 ｎｄ The glass transition temperature and melting point were measured using run. <Measurement conditions for glass transition temperature> Using a differential scanning calorimetry analyzer "DSC822" (manufactured by Mettler Toledo Co., Ltd.), the block copolymer (A) or polymer at 25°C was heated to 200°C at a heating rate of 10°C / min (1 ｓｔ (run), held at 200°C for 5 minutes, then cooled from 200°C to 75°C at a rate of 10°C / min, and held at 75°C for 30 minutes (crystallization). Subsequently, cooled from 75°C to -50°C at a rate of 10°C / min, cooled from -50°C to -75°C at a rate of 5°C / min, and held at -75°C for 5 minutes. Subsequently, heated from -75°C to 250°C at a rate of 10°C / min (2 ｎｄ (run). If multiple peaks were observed, the melting point of the peak with the highest temperature was used as the melting point of the block copolymer or polymer.

[0070] (4) Softening point The softening points of the tackifier (B) and plasticizer (C) were measured in accordance with JIS K6863:1994. Specifically, the procedure was carried out as follows: A sample (tackifier (B) or plasticizer (C)) was filled into a ring specified in JIS K6863:1994 and held horizontally in a heat transfer medium. A steel ball (diameter 9.53 mm, mass 3.5 ± 0.05 g) specified in JIS K6863:1994 was placed in the center of the sample, and the temperature was increased. The softening point was defined as the temperature at which the sample or ball touched the bottom plate of the ring base due to the weight of the ball. The measurement results of the softening points of the tackifier (B) and plasticizer (C) used in the examples and comparative examples are shown in Table 1.

[0071]

[0072] (5) Adhesion (N / 10mm) The adhesive tapes obtained in the examples and comparative examples were cut to a width of 10 mm and a length of 100 mm, and attached to a bright-annealed stainless steel (SUS304) plate to form a test specimen. After storing the test specimen at room temperature for 24 hours, the adhesive tape was peeled off at a speed of 300 mm / min in a 180° direction under conditions of 23°C, and the adhesion force was measured using "AGS-50NX" (manufactured by Shimadzu Corporation). If stick-slip occurred, the maximum value was taken as the adhesion force.

[0073] (6) Holding force (minutes, mm) The adhesive tapes obtained in the examples and comparative examples were cut and attached to a stainless steel (SUS304) plate polished in the same direction with #360 waterproof sandpaper so that the adhesive surface was 25 mm wide and 25 mm long to prepare a test piece. A 1 kg weight was suspended from the test piece and left to stand for 240 minutes under conditions of 40°C, and evaluated according to the following criteria. A: The adhesive tape did not fall. B: The adhesive tape fell. If the adhesive tape fell within 240 minutes, the time until it fell was recorded. If the adhesive tape did not fall, the displacement distance of the adhesive tape after 240 minutes of standing was measured.

[0074] (7) Tackiness A ball tack test was conducted in accordance with JIS Z0237:2009. Specifically, adhesive tapes obtained in the examples and comparative examples were placed on a ball rolling device equipped with an inclined plate with an inclination angle of 30°, and balls conforming to JIS Z0237:2009 were rolled on it. The number of the ball that stopped on the adhesive tape was recorded. The higher the number of the ball, the better the tackiness.

[0075] (8) Peelability The stainless steel plate after peeling off the adhesive tape as described in "(5) Adhesion" above was visually inspected and evaluated according to the following criteria. G: No adhesive residue remains, and the peeled surface is smooth. B: Adhesive residue remains, and the peeled surface is not smooth.

[0076] (9) Contact Angle The contact angles of the polymer consisting of block structural units (a1) with water (contact angle (x)), the polymer consisting of block structural units (a2) with water (contact angle (y)), and the tackifier (B) with water (contact angle (z)) were measured in accordance with the static drop method of JIS R3257:1999. Specifically, each component was sandwiched between a 50 μm thick polyester film and a 50 μm thick release polyester film, and the pressure was reduced to -0.1 MPaG using a vacuum hot press device "IMC-183B" (manufactured by Imoto Seisakusho Co., Ltd.) with an oil rotary pump, and pressed at 80 kN for 1 minute at the temperature shown in Table 3. Subsequently, a sheet with a thickness of 50 μm was produced by pressing at 8 MPaG for 1 minute using a cooling press device equipped with water flow cooling. Subsequently, ion-exchanged water was dropped onto the molded sheet, and the contact angle with water was measured under the following conditions. The measurement results are shown in Table 3. <Measurement Conditions> Measuring device: OCA20 (manufactured by Eiko Seiki Co., Ltd.) Temperature: 23℃ Solvent: Ion-exchanged water Droplet volume: 2.0 μL Measurement time: Within 5 seconds after dropping

[0077] [Synthesis Example 1] In a flask equipped with a device for distilling off the generated liquid and a vacuum pump, 0.66 equivalents of adipic acid were added to "Kuraray Polyol P-6010," the pressure was reduced to 2,000 Pa and the reaction was carried out for 3 hours, then the pressure was reduced to 100 Pa and the reaction was carried out while checking as appropriate until the number average molecular weight reached 40,000, thereby obtaining a polymer (a polymer consisting of polymer (a-1) and polyester units (a1-1)). Toluene was added to the obtained polymer so that the solid content was 18% by mass, and the temperature was raised to 140°C to distill off 10% by mass of the added toluene and dehydrate the system. Subsequently, after cooling to 80°C, L-lactide was added so that the mass ratio of polymer / L-lactide was 60 / 40, and the amount of toluene that was distilled off as described above was added to adjust the solid content of the toluene solution of polymer and L-lactide to 30% by mass. Subsequently, when the temperature of the toluene solution of the polymer and L-lactide was raised to 100°C, 0.2% by mass of tin octylate was added relative to the polymer, and the mixture was reacted for 4 hours to obtain a toluene solution of block copolymer (A-1). This solution was further diluted by adding toluene to obtain a solid content of 20% by mass. Then, the toluene solution with a solid content of 20% by mass was added to twice the volume of methanol (by mass) of the total solution to precipitate the solid. The supernatant methanol was discarded, and the same volume of methanol (by mass) as the amount of toluene solution added was added again for washing. The methanol was discarded, and the recovered solid was dried in a vacuum dryer at 40°C to remove organic volatiles and obtain purified block copolymer (A-1). The polymer consisting of the obtained polyester units (a1-1) and block copolymer (A-1) were subjected to the above-described measurements and evaluations. The results are shown in Tables 2 and 3.

[0078] [Synthesis Examples 2-6] Block copolymers (A-2) to (A-6) having the molecular weights (Mw and Mn) and hard ratios shown in Table 1 were synthesized in the same manner as in Example 1, except that the number-average molecular weight of the block structural unit (a1) was adjusted by adjusting the reaction time during the synthesis of the polymer consisting of polyester units (a1-1), and the mass ratio of the polymer consisting of polyester units (a1-1) to L-lactide was changed. The obtained polymer consisting of polyester units (a1-1) and block copolymers (A-2) to (A-6) were subjected to the measurements and evaluations described above. The results are shown in Table 2.

[0079] [Synthesis Example 7] 190 g of 2-methyl-1,3-propanediol and 281 g of adipic acid were added to a flask equipped with a device for distilling off the generated liquid and a vacuum pump, and the mixture was reacted at 220°C for 2 hours. 0.584 g of potassium titanium oxalate dihydrate was then added and the mixture was reacted for 6 hours. The reaction was carried out under reduced pressure to 100 Pa, while checking the reaction as needed until the number average molecular weight reached 26,000, thereby obtaining a polymer (a polymer (a-2) and a polyester unit (a1-1)). To the obtained polymer, toluene was added so that the solid content was 18% by mass, and the temperature was raised to 140°C to distill off 10% by mass of the added toluene and dehydrate the system. Subsequently, after cooling to 80°C, L-lactide was added so that the mass ratio of polymer / L-lactide was 67 / 33, and the amount of toluene that had been distilled off as described above was added to adjust the solid content of the toluene solution of the polymer and L-lactide to 30% by mass. Subsequently, when the temperature of the toluene solution of the polymer and L-lactide was raised to 100°C, 0.2% by mass of tin octylate was added relative to the polymer, and the mixture was reacted for 4 hours to obtain a toluene solution of block copolymer (A-7). This solution was further diluted by adding toluene to obtain a solid content of 20% by mass. Then, the toluene solution with a solid content of 20% by mass was added to twice the volume of methanol (by mass) of the total solution to precipitate the solid. The supernatant methanol was discarded, and the same volume of methanol (by mass) as the amount of toluene solution added was added again for washing. The methanol was discarded, and the recovered solid was dried in a vacuum dryer at 40°C to remove organic volatiles and obtain purified block copolymer (A-7). The polymer consisting of the obtained polyester units (a1-1) and block copolymer (A-7) were subjected to the above-described measurements and evaluations. The results are shown in Table 2.

[0080] [Comparative Synthesis Example 1] In a flask equipped with a device for distilling off the generated liquid and a vacuum pump, 0.66 equivalents of adipic acid were added to "Kuraray Polyol P-6010," the pressure was reduced to 2,000 Pa and the reaction was carried out for 3 hours. Then, the pressure was reduced to 100 Pa and the reaction was carried out while checking as needed until the number average molecular weight reached 40,000, thereby obtaining polymer (A'-1). The obtained polymer (A'-1) was subjected to the above-described measurements and evaluations. The results are shown in Tables 2 and 3.

[0081] [Comparative Synthesis Example 2] The above measurements and evaluations were performed on the polylactic acid polymer (A'-2) "INGEO 2003D" (manufactured by NatureWorks Co., Ltd.). The results are shown in Table 2.

[0082]

[0083]

[0084] [Examples 1-21 and Comparative Examples 1-3] (1) Production of the composition Block copolymer (A) or polymer, tackifier (B), and plasticizer (C) were dissolved in chloroform in the composition ratios shown in Tables 2-4, and then dried at 40°C using a vacuum dryer to remove organic volatiles and obtain the composition.

[0085] (2) Manufacturing of the adhesive sheet The obtained composition was sandwiched between a 50 μm thick polyester film and a 50 μm thick release polyester film. Using a vacuum heat press "IMC-183B" (manufactured by Imoto Seisakusho Co., Ltd.), the pressure was reduced to -0.1 MPaG using an oil rotary pump, preheated at 200°C for 4 minutes, and then pressed at 80 kN for 1 minute. Subsequently, it was pressed at 8 MPaG for 1 minute using a cooling press equipped with water flow cooling to produce an adhesive sheet made of the composition with a thickness of 50 μm. The obtained adhesive sheet was subjected to the measurements and evaluations described above. The results are shown in Tables 2 to 4.

[0086]

[0087]

[0088]

[0089] As shown in the examples, the composition of this embodiment, containing a specific block copolymer (A) and a tackifier (B), exhibits an excellent balance of adhesiveness, retention, and tackiness. Therefore, the industrial utility of the composition of this embodiment is extremely high.

Claims

1. A composition comprising a block copolymer (A) and a tackifier (B), wherein the block copolymer (A) comprises a block structural unit (a1) and a block structural unit (a2), the block structural unit (a1) mainly comprises a polyester unit (a1-1) containing units derived from an aliphatic diol (a1-1-1) and an aliphatic dicarboxylic acid (a1-1-2), and the block structural unit (a2) mainly comprises a unit (a2-1) derived from at least one selected from the group consisting of hydroxycarboxylic acids and hydroxycarboxylic acid condensates.

2. The composition according to claim 1, satisfying the following formulas (1) and (2): |Contact angle (x) - Contact angle (z)| ≤ 10° (1) |Contact angle (y) - Contact angle (z)| ≥ 5° (2) (In formulas (1) and (2), contact angle (x) is the contact angle of the polymer consisting of the block structure unit (a1) with water, contact angle (y) is the contact angle of the polymer consisting of the block structure unit (a2) with water, and contact angle (z) is the contact angle of the tackifier (B) with water.) 3. The composition according to claim 1 or 2, wherein the number average molecular weight of the block copolymer (A) is greater than 10,000.

4. The composition according to claim 1 or 2, wherein the block structure unit (a2) mainly comprises a polylactic acid unit (a2-1-1) containing a unit selected from the group consisting of lactic acid and lactic acid condensates.

5. The composition according to claim 1 or 2, wherein the aliphatic diol (a1-1-1) has an alkyl group as a branched chain and the main chain has 3 or more carbon atoms.

6. The composition according to claim 5, wherein the branched chain is a methyl group.

7. The composition according to claim 1 or 2, wherein the total number of carbon atoms in the aliphatic diol (a1-1-1) is 4 to 18.

8. The composition according to claim 1 or 2, wherein the aliphatic diol (a1-1-1) is 3-methyl-1,5-pentanediol.

9. The composition according to claim 1 or 2, wherein the total number of carbon atoms of the aliphatic dicarboxylic acid (a1-1-2) is 4 to 18.

10. The composition according to claim 1 or 2, wherein the melting point of the block copolymer (A) is 125°C or higher.

11. The composition according to claim 1 or 2, wherein the content of block structural units (a2) in the block copolymer (A) is 15 to 65% by mass.

12. The composition according to claim 1 or 2, comprising a plasticizer (C).

13. A hot melt adhesive comprising the composition according to claim 1 or 2.

14. A laminate comprising the composition according to claim 1 or 2.

15. A laminate comprising the hot melt adhesive described in claim 13.

Images