Adhesive composition and production method for adhesive composition

Abstract

Provided are: an adhesive composition that is highly bio-based and has suitable adhesion and high thermal resistance; and a production method for the same. This adhesive composition comprises: a block copolymer (X) that includes a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound; and a tackifier (Y). The block copolymer (X) includes, as the polymer block (B), at least one polymer block (B-1) containing a structural unit derived from β-farnesene, and the block copolymer (X) includes at least one block copolymer selected from the group consisting of a non-hydrogenated block copolymer (X0), which is a block copolymer that has not been hydrogenated, and a hydrogenated block copolymer (X1), which is a block copolymer that has been hydrogenated and which has a degree of hydrogenation of less than 50 mol%.

Description

Adhesive composition and method for producing adhesive composition

[0001] The present invention relates to an adhesive composition and a method for producing an adhesive composition.

[0002] Pressure-sensitive adhesive compositions comprising a block copolymer of a polymer block containing structural units derived from an aromatic vinyl compound such as styrene and a polymer block containing structural units derived from a conjugated diene compound are known. Such pressure-sensitive adhesive compositions are widely used because they have predetermined adhesive properties and excellent application workability. In recent years, there has been a growing demand for pressure-sensitive adhesive compositions that are environmentally friendly and contain natural ingredients. For example, Patent Document 1 describes an adhesive composition comprising a block copolymer containing a polystyrene block and a polyfarnesene block. β-Farnesene, which is used to form the polyfarnesene block, is obtained by fermenting sugars from sugarcane, and therefore can increase the biomass ratio of the adhesive composition.

[0003] Special Publication No. 2012-502135

[0004]

[0013] In recent years, as the applications of pressure-sensitive adhesive compositions comprising the above-mentioned block copolymers have expanded, there are cases where the pressure-sensitive adhesive compositions are required to have high heat resistance in addition to appropriate pressure-sensitive adhesive properties. For this reason, the reality is that there is still room for improvement in pressure-sensitive adhesive compositions comprising the above-mentioned block copolymers.

[0005] Therefore, an object of the present invention is to provide a pressure-sensitive adhesive composition that has a high bio-based content and is also provided with appropriate pressure-sensitive adhesive properties and high heat resistance, and a method for producing the same.

[0006] The present inventors have found that in a pressure-sensitive adhesive composition comprising a block copolymer (X) including a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound, and a tackifier (Y), the above-mentioned problems can be solved by specifying the structural unit derived from the conjugated diene compound in the polymer block (B), and have thus completed the present invention.

[0007] The present invention relates to the following items [1] to

[13] . [1] A pressure-sensitive adhesive composition comprising: a block copolymer (X) including a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound; and a tackifier (Y), wherein the block copolymer (X) includes, as the polymer block (B), at least one polymer block (B-1) containing a structural unit derived from β-farnesene, and the block copolymer (X) comprises at least one selected from the group consisting of an unhydrogenated block copolymer (X0) that is a block copolymer that has not been hydrogenated, and a hydrogenated block copolymer (X1) that is a block copolymer that has been hydrogenated and has a hydrogenation rate of less than 50 mol%. [2] The pressure-sensitive adhesive composition according to item [1] above, wherein the content of the tackifier (Y) is 50 to 170 parts by mass relative to 100 parts by mass of the block copolymer (X). [3] The pressure-sensitive adhesive composition according to the above [1] or [2], wherein the block copolymer (X) does not contain a diblock copolymer composed of polymer block (A) and polymer block (B), or the content of the diblock copolymer in the block copolymer (X) is more than 0 mass% and less than 60 mass%. [4] The pressure-sensitive adhesive composition according to any one of the above [1] to [3], wherein at least one selected from the group consisting of an unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol% is crosslinked. [5] The pressure-sensitive adhesive composition according to any one of the above [1] to [4], wherein the block copolymer (X) has a glass transition temperature (Tg) of −52° C. or lower. [6] The pressure-sensitive adhesive composition according to any one of the above [1] to [5], further comprising at least one selected from the group consisting of a liquid rubber component (Za), a biomass-derived plasticizer (Zb), and a synthetic plasticizer (Zc). [7] The pressure-sensitive adhesive composition according to any one of the above-mentioned [1] to [6], further comprising a liquid rubber component (Za), wherein the liquid rubber component (Za) comprises at least one selected from the group consisting of an unhydrogenated liquid rubber (Za0) that is a liquid rubber that has not been hydrogenated, and a hydrogenated liquid rubber (Za1) that is a hydrogenated liquid rubber and has a hydrogenation rate of 90 mol% or less.[8] The pressure-sensitive adhesive composition according to any one of the above [1] to [7], having a 180° peel strength of 10.0 N / 25 mm or more, measured at a temperature of 23°C and a peel rate of 200 mm / min in accordance with JIS Z 0237: 2009. [9] The pressure-sensitive adhesive composition according to the above [4], having a shear interface fracture temperature (SAFT) of 200°C or more, calculated from the weight drop time under the following conditions: adhesive area of ​​25 mm x 25 mm, weight of 500 g, temperature range of 40 to 205°C, and heating rate of 0.5°C / min in accordance with ASTM D3654M: 2019.

[10] The pressure-sensitive adhesive composition according to any one of the above [1] to [9], having a biobased content of 10 to 100 mass%, measured in accordance with ASTM D6866-21.

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

[10] , wherein the vinyl bond content in the polymer block (B-1) is 3 to 20 mol %.

[12] The pressure-sensitive adhesive composition according to any one of the above [1] to

[11] , wherein the content of the polymer block (A) in the block copolymer (X) is 40 mass % or less.

[13] A method for producing the pressure-sensitive adhesive composition according to any one of the above [1] to

[12] , comprising: (I) a step of dissolving the block copolymer (X) and the tackifier (Y) in a solvent and then distilling off the solvent, or (II) a step of melt-kneading the block copolymer (X) and the tackifier (Y).

[0008] According to the present invention, it is possible to provide a pressure-sensitive adhesive composition that has a high bio-based content and is provided with appropriate pressure-sensitive adhesive properties and high heat resistance, and a method for producing the same.

[0009] Hereinafter, embodiments of the present invention will be described. The present invention also includes any embodiment in which the matters described in this specification are arbitrarily selected or arbitrarily combined. In this specification, preferred definitions can be selected arbitrarily, and combinations of preferred definitions can be considered more preferable. In this specification, the expression "XX to YY" means "XX or more and YY or less." In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), lower and upper limits described in stages can be independently combined. For example, from the description "preferably 10 to 90, more preferably 30 to 60," the "preferable lower limit (10)" and the "more preferable upper limit (60)" can be combined to form "10 to 60."

[0010] [Adhesive Composition] The adhesive composition according to an embodiment of the present invention comprises a block copolymer (X) including a polymer block (A) containing structural units derived from an aromatic vinyl compound and a polymer block (B) containing structural units derived from a conjugated diene compound, and a tackifier (Y). The block copolymer (X) comprises at least one polymer block (B-1) containing structural units derived from β-farnesene as the polymer block (B). The block copolymer (X) further comprises at least one selected from the group consisting of an unhydrogenated block copolymer (X0) that is a block copolymer that has not been hydrogenated, and a hydrogenated block copolymer (X1) that is a block copolymer that has been hydrogenated and has a hydrogenation rate of less than 50 mol%.

[0011] The adhesive composition can have a high biobased content because the polymer block (B) contained in the block copolymer (X) contains at least one polymer block (B-1) containing a structural unit derived from β-farnesene. Furthermore, by containing the polymer block (B-1) containing a structural unit derived from β-farnesene, the block copolymer (X) has a low viscosity and flexibility, and the adhesive composition containing the block copolymer (X) can easily conform to the irregularities of an adherend. Furthermore, the block copolymer (X) contains at least one selected from the group consisting of an unhydrogenated block copolymer (X0), which is a block copolymer that has not been hydrogenated, and a hydrogenated block copolymer (X1), which is a block copolymer that has been hydrogenated and has a hydrogenation rate of less than 50 mol%. Therefore, the block copolymer (X) has many double bonds, has high crosslinkability, and can be easily crosslinked with a low dose of energy rays such as ultraviolet (UV) radiation. In particular, the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol% are considered to have higher reactivity than, for example, a hydrogenated block copolymer having a hydrogenation rate of 50 mol% or more, because the branched double bonds are thought to be involved in the crosslinking reaction. Therefore, crosslinking can increase the heat resistance of the pressure-sensitive adhesive composition, and can ensure appropriate pressure-sensitive adhesive properties.

[0012] The pressure-sensitive adhesive composition may contain only the block copolymer (X) and the tackifier (Y), or may contain the block copolymer (X), the tackifier (Y), and other components. The total content of the block copolymer (X) and the tackifier (Y) in the pressure-sensitive adhesive composition is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the total mass of the pressure-sensitive adhesive composition. It may also be 100% by mass or less, 95% by mass or less, or 90% by mass or less. In other words, the total content of the block copolymer (X) and the tackifier (Y) in the pressure-sensitive adhesive composition is preferably 50 to 100% by mass, based on the total mass of the pressure-sensitive adhesive composition. When forming a pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition, a method can be used in which the pressure-sensitive adhesive composition is dissolved in a suitable solvent, coated on a suitable support or adherend, and dried to form a coating film. The pressure-sensitive adhesive composition can also be used as a hot-melt pressure-sensitive adhesive composition. In this case, the adhesive composition is heated to reduce the viscosity and then supplied onto the first adherend, or the adhesive composition is placed on the first adherend and then heated to reduce the viscosity, and then a second adherend is placed on top of the adhesive composition, thereby adhesively adhering the two adherends.

[0013] <Block Copolymer (X)> The block copolymer (X) comprises a polymer block (A) containing structural units derived from an aromatic vinyl compound and a polymer block (B) containing structural units derived from a conjugated diene compound. The block copolymer (X) comprises, as the polymer block (B), at least one polymer block (B-1) containing structural units derived from β-farnesene. Therefore, the biobased content of the pressure-sensitive adhesive composition can be increased compared to a case in which the polymer block (B-1) is not contained. Furthermore, since the polymer block (B-1) contains structural units derived from β-farnesene, and this β-farnesene has a bulky side chain, it is believed that the entanglement of molecules is reduced, resulting in a lower viscosity and an increased affinity between the tackifier (Y) and the block copolymer (X). As a result, the pressure-sensitive adhesive composition can contain a high content of the tackifier (Y). The polymer block (B) will be described in detail later.

[0014] As described above, the block copolymer (X) comprises at least one selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, and may further comprise a hydrogenated block copolymer having a hydrogenation rate of 50 mol% or more to adjust the hydrogenation rate. The block copolymer (X) preferably consists essentially of the unhydrogenated block copolymer (X0), the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, or both the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, and more preferably consists essentially of the unhydrogenated block copolymer (X0). Here, "substantially" means that the block copolymer may comprise only the unhydrogenated block copolymer (X0) or the hydrogenated block copolymer (X1), or may also comprise components, such as hydrogenated block copolymers having a hydrogenation rate of 50 mol% or more, which are inevitably present during the production of the block copolymer.

[0015] When the block copolymer (X) contains both an unhydrogenated block copolymer (X0) and a hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, the unhydrogenated block copolymer used to obtain the latter is preferably the same as the former, from the viewpoint of facilitating the attainment of desired physical properties. However, as long as the effects of the present invention are not impaired, an unhydrogenated block copolymer having a molecular weight different from that of the former, or an unhydrogenated block copolymer having a structural unit different from that of the former, may be used as the unhydrogenated block copolymer to obtain the latter.

[0016] When the block copolymer (X) contains a hydrogenated block copolymer having a hydrogenation rate of 50 mol % or more for adjusting the hydrogenation rate as described above, the content thereof is not particularly limited, but from the viewpoint of making it easier to adjust the hydrogenation rate while ensuring the desired performance of the block copolymer (X), it is preferably 0 to 60 mass %, more preferably 0 to 50 mass %, based on the mass of the block copolymer (X).

[0017]

[0113] The glass transition temperature (Tg) of the block copolymer (X) is preferably -52°C or lower, more preferably -54°C or lower, and even more preferably -57°C or lower, from the viewpoint of easily ensuring the cold resistance of the adhesive composition and the adhesive strength during high-speed peeling.

[0018] Hereinafter, each component constituting the block copolymer (X) will be described, but unless otherwise specified, these descriptions apply to both the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1).

[0019] (Polymer Block (A)) The polymer block (A) contains a structural unit derived from an aromatic vinyl compound (hereinafter, sometimes referred to as an "aromatic vinyl compound unit"). Examples of such aromatic vinyl compounds include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 2,4,6-trimethylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 1-vinylnaphthalene, 2-vinylnaphthalene, vinylanthracene, N,N-diethyl-4-aminoethylstyrene, vinylpyridine, 4-methoxystyrene, monochlorostyrene, dichlorostyrene, and divinylbenzene. These aromatic vinyl compounds may be used alone or in combination of two or more. Among these, styrene, α-methylstyrene, and 4-methylstyrene are preferred, and styrene is more preferred.

[0020] The polymer block (A) may contain structural units derived from monomers other than aromatic vinyl compounds, such as monomers constituting the polymer block (B) described below. However, the content of aromatic vinyl compound units in the polymer block (A) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. The upper limit of the content of aromatic vinyl compound units in the polymer block (A) may be 100% by mass, 99% by mass, or 98% by mass. In other words, the content of aromatic vinyl compound units in the polymer block (A) is preferably 60 to 100% by mass.

[0021] The block copolymer (X) may have at least one polymer block (A). When the block copolymer (X) has two or more polymer blocks (A), the polymer blocks (A) may be the same or different. In this specification, "different polymer blocks" means that the polymer blocks are different in at least one of the monomer units constituting the polymer blocks, the weight-average molecular weight, the stereoregularity, and, when a plurality of monomer units are present, the ratio of the respective monomer units and the copolymerization form (random, Taber, block). From the viewpoint of the heat resistance and adhesion retention (creep property) of the pressure-sensitive adhesive composition, it is preferable that the block copolymer (X) has two or more polymer blocks (A).

[0022] The content of polymer block (A) in block copolymer (X) (when multiple polymer blocks (A) are present, the total content thereof) is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less, and particularly preferably 25% by mass or less, from the viewpoint of flexibility, and is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, from the viewpoint of the balance between adhesive strength and heat resistance. In other words, the content of polymer block (A) in block copolymer (X) is preferably 3 to 35% by mass. The content of polymer block (A) in block copolymer (X) is １ The value was determined by H-NMR measurement, more specifically, the value was measured according to the method described in the Examples.

[0023] From the viewpoints of coatability and heat resistance, the weight average molecular weight (Mw) of the polymer block (A) is preferably 3,000 to 60,000, more preferably 4,000 to 50,000, even more preferably 5,000 to 40,000, still more preferably 5,500 to 30,000, and even more preferably 6,000 to 20,000. The weight average molecular weight (Mw) of the polymer block (A) can be adjusted to the above range, for example, by adjusting the amount of the aromatic vinyl compound relative to the polymerization initiator used in the polymerization.

[0024] The "weight average molecular weight" described in this specification and claims is a weight average molecular weight calculated in terms of standard polystyrene by gel permeation chromatography (GPC), and the detailed measurement method can be the same as that described in the Examples.

[0025] (Polymer Block (B)) The polymer block (B) contains a structural unit derived from a conjugated diene compound (hereinafter, sometimes abbreviated as a "conjugated diene compound unit"). The block copolymer (X) used in the present invention contains, as the polymer block (B), at least one polymer block (B-1) containing a structural unit derived from β-farnesene.

[0026] The block copolymer (X) used in the present invention may further contain, as the polymer block (B), a polymer block (B-2) that contains structural units derived from a conjugated diene compound other than β-farnesene but does not contain structural units derived from β-farnesene, in addition to the polymer block (B-1). The polymer blocks (B-1) and (B-2) will be described in detail later.

[0027] From the viewpoint of suppressing crystallization of the polymer block (B) and ensuring strength, the total content of structural units derived from β-farnesene in the polymer block (B) is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, still more preferably 40% by mass or more, even more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. There is no particular upper limit, and it may be 100% by mass, 99% by mass or less, or 98% by mass or less. In other words, the total content of structural units derived from β-farnesene in the polymer block (B) is preferably 10 to 100% by mass.

[0028] The polymer block (B) may contain a structural unit derived from β-farnesene and a structural unit derived from at least one selected from the group consisting of butadiene, isoprene, and myrcene. In this case, (a) the block copolymer (X) may contain the above-mentioned polymer block (B-1) and polymer block (B-2), and the polymer block (B-2) may contain a structural unit derived from at least one selected from the group consisting of butadiene, isoprene, and myrcene, or (b) the polymer block (B-1) may contain a structural unit derived from β-farnesene and a structural unit derived from at least one selected from the group consisting of butadiene, isoprene, and myrcene.

[0029] The content of conjugated diene compound units in the total amount of polymer block (B) (i.e., the total content of structural units derived from β-farnesene and structural units derived from conjugated diene compounds other than β-farnesene) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably substantially 100% by mass, from the viewpoints of flexibility and biobasedness. There is no particular upper limit, and it may be 100% by mass, 99% by mass, or 98% by mass. In other words, the content of conjugated diene compound units in the total amount of polymer block (B) is preferably 60 to 100% by mass. The content of the conjugated diene compound units in the total amount of polymer block (B) is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 65 mol% or more, still more preferably 80 mol% or more, particularly preferably 90 mol% or more, and most preferably substantially 100 mol%. The upper limit of the content of the conjugated diene compound units in the total amount of polymer block (B) may be 100 mol%, 99 mol%, or 98 mol%. In other words, the content of the conjugated diene compound units in the total amount of polymer block (B) is preferably 30 to 100 mol%.

[0030] The mixing ratio of the conjugated diene compounds in the entire polymer block (B) [β-farnesene / conjugated diene compounds other than β-farnesene] (mass ratio) is not particularly limited as long as the effects of the present invention are not impaired, but from the viewpoints of increasing the biobased content and reducing viscosity, it is preferably 3 / 97 to 100 / 0, more preferably 40 / 60 to 100 / 0, even more preferably 50 / 50 to 100 / 0, still more preferably 70 / 30 to 100 / 0, still more preferably 80 / 20 to 100 / 0, still more preferably 85 / 15 to 100 / 0, and particularly preferably 90 / 10 to 100 / 0. From the viewpoint of increasing cohesive strength, it is preferably 3 / 97 to 90 / 10, more preferably 5 / 95 to 85 / 15, even more preferably 10 / 90 to 45 / 55, and particularly preferably 15 / 85 to 40 / 60. From the viewpoint of the balance between the degree of bio-based content, low viscosity, and cohesive strength, the ratio may be 25 / 75 to 65 / 35, or may be 30 / 70 to 60 / 40.

[0031] As long as the objectives and effects of the present invention are not impaired, polymer block (B) may contain structural units derived from polymerizable monomers other than conjugated diene compounds. In this case, the content of structural units derived from polymerizable monomers other than conjugated diene compounds in polymer block (B) is preferably 70 mol% or less, more preferably 50 mol% or less, even more preferably 35 mol% or less, even more preferably 20 mol% or less, and particularly preferably 10 mol% or less. There is no particular restriction on the lower limit of the content of structural units derived from polymerizable monomers other than conjugated diene compounds, but it may be 0 mol% or 5 mol%. In other words, the content of structural units derived from polymerizable monomers other than conjugated diene compounds in polymer block (B) is preferably 0 to 70 mol%.

[0032] The total weight average molecular weight of the polymer blocks (B) in the block copolymer (X) is preferably 30,000 to 300,000, more preferably 40,000 to 250,000, and even more preferably 50,000 to 200,000, before hydrogenation, from the viewpoints of coatability, heat resistance, and the like.

[0033] (Polymer Block (B-1)) The polymer block (B-1) contains a structural unit (b11) derived from β-farnesene (hereinafter, sometimes simply referred to as "structural unit (b11)"). The content of the structural unit (b11) in the polymer block (B-1) is preferably 1 to 100% by mass. The structural unit (b11) has a long and bulky side chain in the molecule, and therefore, when the polymer block (B-1) contains the structural unit (b11), the flexibility of the block copolymer (X) is improved. From this viewpoint, the content of the structural unit (b11) in the polymer block (B-1) is more preferably 10 to 100% by mass, even more preferably 20 to 100% by mass, even more preferably 30 to 100% by mass, particularly preferably 50 to 100% by mass, and most preferably 100% by mass, i.e., the polymer block (B-1) consists solely of the structural unit (b11). Furthermore, because β-farnesene is bio-derived, the amount of conjugated diene compounds other than β-farnesene, such as petroleum-derived butadiene and isoprene, used can be reduced, thereby reducing dependency on petroleum. From this viewpoint, the content of the structural unit (b11) in the polymer block (B-1) is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, even more preferably 70 to 100% by mass, and even more preferably 80 to 100% by mass. Furthermore, when the polymer block (B-1) contains the structural unit (b12) described below, the content of the structural unit (b11) in the polymer block (B-1) is preferably 1 to 99% by mass, more preferably 10 to 99% by mass, even more preferably 20 to 99% by mass, even more preferably 30 to 99% by mass, and particularly preferably 50 to 99% by mass.

[0034] The polymer block (B-1) may contain a structural unit (b12) (hereinafter also simply referred to as "structural unit (b12)") derived from a conjugated diene compound other than β-farnesene, and the content of the structural unit (b12) in the polymer block (B-1) is preferably 0 to 99 mass%. Such conjugated diene compounds are preferably conjugated diene compounds not having a farnesene skeleton, such as isoprene, butadiene, 2,3-dimethyl-butadiene, 2-phenyl-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 1,3-cyclohexadiene, 2-methyl-1,3-octadiene, 1,3,7-octatriene, myrcene, and chloroprene. These may be used alone or in combination of two or more. Among these, isoprene, butadiene, and myrcene are preferred, and isoprene and butadiene are more preferred. When the polymer block (B-1) contains the structural unit (b12), the content of the structural unit (b12) is more preferably 90% by mass or less, even more preferably 80% by mass or less, even more preferably 70% by mass or less, and particularly preferably 50% by mass or less.

[0035] The polymer block (B-1) may contain structural units other than the structural unit (b11) and the structural unit (b12). The total content of the structural unit (b11) and the structural unit (b12) in the polymer block (B-1) is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 100% by mass.

[0036] The weight average molecular weight (Mw) of the polymer block (B-1) is preferably 30,000 to 300,000, more preferably 40,000 to 250,000, and even more preferably 50,000 to 200,000, from the viewpoints of coatability and heat resistance.

[0037] The block copolymer (X) used in the present invention may contain only the polymer block (B-1) as the polymer block (B), or may further contain the polymer block (B-2) described below. From the viewpoint of the dispersibility of the tackifier (Y), the content of the polymer block (B-1) in the entire polymer block (B) is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, based on the total mass of the polymer block (B). There is no particular upper limit, and it may be 100% by mass or less, 95% by mass or less, or 90% by mass or less. In other words, the content of the polymer block (B-1) in the entire polymer block (B) is preferably 50 to 100% by mass.

[0038] (Polymer Block (B-2)) In addition to the polymer block (B-1), the block copolymer (X) can further include, as the polymer block (B), a polymer block (B-2) containing a structural unit (b22) described below. The polymer block (B-2) does not contain a structural unit derived from β-farnesene. That is, the content of the structural unit (b21) derived from β-farnesene (hereinafter also simply referred to as "structural unit (b21)") in the polymer block (B-2) is 0% by mass.

[0039] Conjugated diene compounds constituting the structural unit (b22) (hereinafter also simply referred to as "structural unit (b22)") derived from a conjugated diene compound other than β-farnesene include the same conjugated diene compounds constituting the structural unit (b12) described above, and preferred examples include isoprene, butadiene, and myrcene. Of these, isoprene and butadiene are more preferred. These may be used alone or in combination of two or more. Furthermore, the polymer block (B-2) may contain structural units other than the structural unit (b22).

[0040] The content of the structural unit (b22) in the polymer block (B-2) is more preferably from 60 to 100% by mass, even more preferably from 80 to 100% by mass, even more preferably from 90 to 100% by mass, and particularly preferably 100% by mass.

[0041] The weight average molecular weight of the polymer block (B-2) is preferably from 4,000 to 200,000, more preferably from 4,500 to 150,000, and even more preferably from 5,000 to 100,000, from the viewpoint of coatability.

[0042] (Bonding Form) The block copolymer (X) contains at least one polymer block (A) and at least one polymer block (B). The bonding form of the polymer block (A) and the polymer block (B) is not particularly limited, and may be linear, branched, radial, or a combination of two or more thereof. Among these, a form in which the blocks are bonded linearly is preferred. As the linear bonding form, when the polymer block (A) is represented by A and the polymer block (B) is represented by B, it is expressed as (A-B) ｌ , A-(B-A) ｍ , or B-(A-B) ｎ Examples of the bonding form include those represented by the formula: where l, m, and n each independently represent an integer of 1 or greater. When the block copolymer (X) contains at least one polymer block (A) and at least one polymer block (B-1), the bonding form preferably has blocks in the order of polymer block (A), polymer block (B-1), and polymer block (A), and is a triblock copolymer represented by A-B1-A. In other words, the block copolymer (X) is preferably a triblock copolymer represented by A-B1-A.

[0043] When the block copolymer (X) contains polymer block (B-1) and polymer block (B-2) as the polymer block (B), the bonding form of the multiple polymer blocks is not particularly limited and may be linear, branched, radial, or a combination of two or more thereof. Among these, a form in which the blocks are bonded linearly is preferred. The block copolymer (X) preferably has a structure having blocks in the order of polymer block (B-1), polymer block (A), and polymer block (B-2) (i.e., a structure of B1-A-B2). Specifically, the block copolymer (X) may be a tetrablock copolymer represented by B1-A-B2-A, a pentablock copolymer represented by B1-A-B2-A-B1, or a copolymer represented by B1-A-(B2-A)ｐ -B1, B1-A- (B2-A-B1) ｑ , B1-(A-B2-A-B1) ｒ (p, q, and r each independently represent an integer of 2 or greater), and particularly preferably a pentablock copolymer represented by B1-A-B2-A-B1. That is, when block copolymer (X) contains polymer block (B-1) and polymer block (B-2) as polymer block (B), block copolymer (X) is preferably a pentablock copolymer represented by B1-A-B2-A-B1.

[0044] Here, in this specification, when polymer blocks of the same type are linearly bonded via a divalent coupling agent or the like, the entirety of the bonded polymer blocks is treated as a single polymer block. Accordingly, polymer blocks that should strictly be expressed as A-X-A (X represents a coupling agent residue) are expressed as a whole as A. In this specification, since this type of polymer block containing a coupling agent residue is treated as above, for example, a block copolymer containing a coupling agent residue and that should strictly be expressed as B1-A-B2-X-B2-A-B1 is expressed as B1-A-B2-A-B1 and is treated as an example of a pentablock copolymer.

[0045] Furthermore, the two or more polymer blocks (A) in the above-mentioned block copolymer (X) may each be a polymer block consisting of the same structural units or a polymer block consisting of different structural units. Similarly, when the block copolymer (X) has two or more polymer blocks (B-1) or two or more polymer blocks (B-2), the respective polymer blocks may each be a polymer block consisting of the same structural units or a polymer block consisting of different structural units. For example, in the two polymer blocks (A) in a triblock copolymer represented by A-B-A, the types of aromatic vinyl compounds in the respective polymer blocks may be the same or different.

[0046] When the block copolymer (X) contains the polymer block (A) and the polymer block (B-1) but does not contain the polymer block (B-2), the mass ratio of the polymer block (A) to the polymer block (B-1) [(A) / (B-1)] is preferably 1 / 99 to 70 / 30, more preferably 5 / 95 to 60 / 40, even more preferably 10 / 90 to 50 / 50, still more preferably 15 / 85 to 40 / 60, and even more preferably 15 / 85 to 35 / 65. When the mass ratio is within this range, a pressure-sensitive adhesive composition having good pressure-sensitive adhesive strength and a high bio-based degree can be obtained. When the block copolymer (X) comprises the polymer block (A), the polymer block (B-1), and the polymer block (B-2), the mass ratio of the polymer block (A) to the polymer block (B-1) [(A) / (B-1)] is preferably 1 / 99 to 70 / 30, more preferably 5 / 95 to 60 / 40, even more preferably 10 / 90 to 50 / 50, even more preferably 20 / 80 to 40 / 60, and even more preferably 25 / 75 to 35 / 65. Within this range, a pressure-sensitive adhesive composition having excellent pressure-sensitive adhesive strength and cohesive strength can be obtained.

[0047] In the block copolymer (X), the mass ratio of the polymer block (A) to the total amount of the polymer block (B-1) and the polymer block (B-2), [(A) / ((B-1)+(B-2)], is preferably 1 / 99 to 70 / 30. Within this range, a pressure-sensitive adhesive composition having an excellent balance between viscosity and elasticity is more easily obtained. From this viewpoint, the mass ratio [(A) / ((B-1)+(B-2)] is more preferably 1 / 99 to 60 / 40, even more preferably 10 / 90 to 40 / 60, still more preferably 10 / 90 to 30 / 70, and still more preferably 15 / 85 to 25 / 75.

[0048] When the block copolymer (X) contains the polymer block (A), the polymer block (B-1), and the polymer block (B-2), the total content of the structural unit (b11) and the structural unit (b21) relative to the total amount of the polymer block (B-1) and the polymer block (B-2) in the block copolymer [((b11) + (b21)) / ((B-1) + (B-2)] is preferably 40 to 90 mass%, more preferably 50 to 80 mass%, and even more preferably 60 to 70 mass%, from the viewpoint of flexibility.

[0049] When the block copolymer (X) contains the polymer block (A) and the polymer block (B-1) but does not contain the polymer block (B-2), the total content of the polymer block (A) and the polymer block (B-1) in the block copolymer (X) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. That is, the total content of the polymer block (A) and the polymer block (B-1) in the block copolymer (X) is, for example, 80 to 100% by mass. Furthermore, when the block copolymer (X) contains the polymer block (A), the polymer block (B-1), and the polymer block (B-2), the total content of these polymer blocks (A), (B-1), and (B-2) in the block copolymer (X) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. That is, the total content of the polymer blocks (A), (B-1), and (B-2) in the block copolymer (X) is, for example, 80 to 100% by mass.

[0050] From the viewpoint of suppressing a decrease in the dispersibility of the tackifier (Y), the content of the polymer block (B-2) in the entire polymer block (B) is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, and may be 10% by mass or more, or 20% by mass or more, but is preferably 0% by mass. In other words, the content of the polymer block (B-1) in the entire polymer block (B) is preferably 0 to 50% by mass.

[0051] (Amount of Vinyl Bonds in Polymer Block (B)) There are no particular limitations on the bonding form of the conjugated diene compound, as long as it does not impair the objects and effects of the present invention. For example, when the structural units constituting polymer block (B) are structural units derived from β-farnesene, structural units derived from β-farnesene and butadiene, or structural units derived from β-farnesene and isoprene, the bonding forms of β-farnesene, butadiene, and isoprene can be 1,2-bonds, 1,13-bonds, and 3,13-bonds in the case of β-farnesene, 1,2-bonds and 1,4-bonds in the case of butadiene, and 1,2-bonds, 3,4-bonds, and 1,4-bonds in the case of isoprene. Only one type of these bonding forms may be present, or two or more types may be present. Among these, the 1,2-bond and 3,13-bond of β-farnesene, the 1,2-bond of butadiene, and the 1,2-bond and 3,4-bond of isoprene are considered to be vinyl bond units, and the content of vinyl bond units is considered to be the vinyl bond amount. Note that the carbon position numbers of β-farnesene are assigned in the following order:

[0052]

[0053] In the block copolymer (X), the vinyl bond content of the polymer block (B-1) is preferably 20 mol % or less, more preferably 15 mol % or less, and even more preferably 10 mol % or less, from the viewpoint of lowering the glass transition temperature (Tg) of the polymer block (B-1) and from the viewpoint of ease of production. Furthermore, although not particularly limited, the lower limit of the vinyl bond content in the polymer block (B-1) may be 3 mol % or more, 4 mol % or more, or 5 mol % or more, from the viewpoint of ease of production. In other words, the vinyl bond content in the polymer block (B-1) is preferably 3 to 20 mol %. Here, the vinyl bond content can be determined according to the method described in the Examples. １The vinyl bond content is a value calculated by H-NMR measurement. When a plurality of polymer blocks (B-1) are present in the block copolymer (X), it is sufficient that the vinyl bond content of at least one of the polymer blocks (B-1) is within the above range, and the vinyl bond content of all of the polymer blocks (B-1) may be within the above range. The vinyl bond content can be adjusted to the above range, for example, by adjusting the type and addition amount of a Lewis base used as a co-catalyst (vinylating agent) during polymerization.

[0054] From the viewpoints of ease of production and lowering Tg, the vinyl bond content in polymer block (B-2) is preferably 20 to 45 mol%, more preferably 25 to 44 mol%, and even more preferably 30 to 43 mol%. The total vinyl bond content in polymer block (B) is preferably 3 to 45 mol%, more preferably 4 to 44 mol%, and even more preferably 5 to 43 mol%.

[0055] (Polymer Blocks Composed of Other Monomers) In addition to the polymer block (A), the polymer block (B-1) and the polymer block (B-2), the block copolymer (X) may contain polymer blocks composed of other monomers, as long as the effects of the present invention are not impaired.

[0056] Examples of such other monomers include unsaturated hydrocarbon compounds such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, and 1-eicosene; and functional group-containing unsaturated compounds such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile, maleic acid, fumaric acid, crotonic acid, itaconic acid, 2-acryloylethanesulfonic acid, 2-methacryloylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, vinylsulfonic acid, vinyl acetate, and methyl vinyl ether. These may be used alone or in combination of two or more. When the block copolymer (X) has other polymer blocks, the content thereof is preferably 10% by mass or less, more preferably 5% by mass or less.

[0057] From the viewpoint of facilitating improved heat resistance, it is preferable that block copolymer (X) does not contain a diblock copolymer consisting of polymer block (A) and polymer block (B), or that the content of the diblock copolymer in block copolymer (X) is more than 0% by mass and less than 60% by mass. In the latter case, the content of the diblock copolymer in block copolymer (X) is more preferably more than 0% by mass and less than 50% by mass, even more preferably more than 0% by mass and less than 40% by mass, even more preferably more than 0% by mass and less than 30% by mass, even more preferably more than 0% by mass and less than 20% by mass, and even more preferably more than 0% by mass and less than 10% by mass. In other words, the total content of multiblock copolymers containing a total of three or more polymer blocks (A) and polymer blocks (B) in block copolymer (X) is preferably more than 40% by mass and less than 100% by mass. Note that components such as unreacted polymer block (A) and unreacted polymer block (B) usually account for less than 1% by mass of the resulting block copolymer (X) and are therefore negligible. Therefore, when such unreacted components are present, the above mass ratio may be set with these components removed.

[0058] From the viewpoint of improving heat resistance, the pressure-sensitive adhesive composition preferably has at least one crosslinked component selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%. Crosslinking of at least one component selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) improves heat resistance, while the presence of the tackifier (Y) ensures a predetermined pressure-sensitive adhesive property. Examples of a method for crosslinking at least one component selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) include a method in which a photoradical polymerization initiator and a crosslinking agent, which will be described later, are incorporated into the pressure-sensitive adhesive composition and then irradiated with ultraviolet light. Components other than the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) may also be crosslinked. For example, at least one component selected from the group consisting of the tackifier (Y) and the liquid rubber component (Z), which will be described later, may also be crosslinked.

[0059] <Method for Producing Block Copolymer (X)> When the block copolymer (X) is, for example, an unhydrogenated block copolymer (X0) containing polymer block (A) and polymer block (B-1), or when the block copolymer (X) is an unhydrogenated block copolymer (X0) containing polymer block (A), polymer block (B-1), and polymer block (B-2), it can be suitably produced by a polymerization step such as anionic polymerization. Furthermore, when the block copolymer (X) is a hydrogenated block copolymer (X1), it can be suitably produced by a step of hydrogenating carbon-carbon double bonds in structural units derived from a conjugated diene compound in the unhydrogenated block copolymer (X0).

[0060] (Polymerization Step) The unhydrogenated block copolymer (X0) can be produced by a solution polymerization method or the methods described in JP-A Nos. 2012-502135 and 2012-502136. Among these, solution polymerization is preferred, and known methods such as ionic polymerization methods such as anionic polymerization and cationic polymerization, and radical polymerization can be applied. Among these, anionic polymerization is preferred. In the anionic polymerization method, an aromatic vinyl compound, β-farnesene, and optionally a conjugated diene compound other than β-farnesene are sequentially added in the presence of a solvent, an anionic polymerization initiator, and, if necessary, a Lewis base, to obtain the unhydrogenated block copolymer (X0). Examples of the anionic polymerization initiator include alkali metals such as lithium, sodium, and potassium; alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium; lanthanoid rare earth metals such as lanthanum and neodymium; and compounds containing the alkali metals, alkaline earth metals, and lanthanoid rare earth metals. Among these, compounds containing alkali metals and alkaline earth metals are preferred, and organic alkali metal compounds are more preferred.

[0061] Examples of the organic alkali metal compound include organic lithium compounds such as methyl lithium, ethyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, stilbene lithium, dilithiomethane, dilithionaphthalene, 1,4-dilithiobutane, 1,4-dilithio-2-ethylcyclohexane, and 1,3,5-trilithiobenzene; sodium naphthalene, and potassium naphthalene. Among these, organic lithium compounds are preferred, with n-butyl lithium and sec-butyl lithium being more preferred, and sec-butyl lithium being even more preferred. The organic alkali metal compound may be reacted with a secondary amine such as diisopropylamine, dibutylamine, dihexylamine, or dibenzylamine to form an organic alkali metal amide. The amount of the organic alkali metal compound used in the polymerization varies depending on the molecular weight of the unhydrogenated block copolymer (X0), but is usually in the range of 0.01 to 3 mass % based on the total amount of the aromatic vinyl compound, β-farnesene, and the conjugated diene compound other than β-farnesene.

[0062] The solvent is not particularly limited as long as it does not adversely affect the anionic polymerization reaction, and examples thereof include saturated aliphatic hydrocarbons such as n-pentane, isopentane, n-hexane, n-heptane, and isooctane; saturated alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; and aromatic hydrocarbons such as benzene, toluene, and xylene. These may be used alone or in combination of two or more. There is no particular limit to the amount of solvent used.

[0063] The Lewis base plays a role in controlling the microstructure of structural units derived from β-farnesene and structural units derived from conjugated diene compounds other than β-farnesene. Examples of such Lewis bases include ether compounds such as dibutyl ether, diethyl ether, tetrahydrofuran, dioxane, and ethylene glycol diethyl ether; pyridine; tertiary amines such as N,N,N',N'-tetramethylethylenediamine and trimethylamine; alkali metal alkoxides such as potassium t-butoxide; and phosphine compounds. When a Lewis base is used, the amount thereof is usually preferably in the range of 0.01 to 1,000 molar equivalents per mole of the anionic polymerization initiator.

[0064] The polymerization reaction temperature is typically about −80 to +150°C, preferably 0 to 100°C, and more preferably 10 to 90°C. The polymerization reaction may be carried out batchwise or continuously. The unhydrogenated block copolymer (X0) can be produced by continuously or intermittently supplying each monomer to the polymerization reaction solution so that the amounts of aromatic vinyl compound, β-farnesene, and conjugated diene compound other than β-farnesene present in the polymerization reaction system are within a specific range, or by sequentially polymerizing each monomer in the polymerization reaction solution so that a specific ratio is achieved. The polymerization reaction can be terminated by adding an alcohol such as methanol or isopropanol as a polymerization terminator. The unhydrogenated block copolymer (X0) can be isolated by pouring the resulting polymerization reaction solution into a poor solvent such as methanol to precipitate it, or by washing the polymerization reaction solution with water, separating it, and then drying it. Methods for isolating the unhydrogenated block copolymer (X0) include a method of solidifying the resin component (steam stripping) and a spray-drying method in which a polymer solution is heated to a high temperature and a high pressure and then sprayed under normal pressure to extract the resin component.

[0065] When the block copolymer (X) is a triblock copolymer represented by the formula A-B1-A, examples of methods for producing the block copolymer (X) include: [i] a method of polymerizing polymer block (A), polymer block (B-1), and polymer block (A) in this order; and [ii] a method of polymerizing polymer block (A) and polymer block (B-1) in this order and coupling the ends of polymer block (B-1) together using a coupling agent. In this embodiment, the method [i] is preferred from the viewpoint of efficient production. Note that when the block copolymer (X) further contains polymer block (B-2), it can also be produced by a method similar to the above method.

[0066] Examples of the coupling agent include divinylbenzene; polyfunctional epoxy compounds such as epoxidized 1,2-polybutadiene, epoxidized soybean oil, and tetraglycidyl-1,3-bisaminomethylcyclohexane; halides such as tin tetrachloride, tetrachlorosilane, trichlorosilane, trichloromethylsilane, dichlorodimethylsilane, and dibromodimethylsilane; methyl benzoate, ethyl benzoate, phenyl benzoate, diethyl oxalate, diethyl malonate, diethyl adipate, and dimethyl phthalate. ester compounds such as dimethyl carbonate, dimethyl terephthalate, etc.; carbonate compounds such as dimethyl carbonate, diethyl carbonate, diphenyl carbonate, etc.; alkoxysilane compounds such as diethoxydimethylsilane, trimethoxymethylsilane, triethoxymethylsilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, tetrakis(2-ethylhexyloxy)silane, bis(triethoxysilyl)ethane, 3-aminopropyltriethoxysilane, etc.; 2,4-tolylene diisocyanate, etc.

[0067] In this polymerization step, an unmodified block copolymer may be obtained as described above, or a modified block copolymer may be obtained as follows. In the case of a modified block copolymer, the unhydrogenated block copolymer (X0) may be modified before the hydrogenation step described below. Examples of functional groups that can be introduced include an amino group, an alkoxysilyl group, a hydroxyl group, an epoxy group, a carboxyl group, a carbonyl group, a mercapto group, an isocyanate group, and an acid anhydride group. Examples of methods for modifying the unhydrogenated block copolymer (X0) include adding, before adding a polymerization terminator, a coupling agent capable of reacting with the polymerization active terminals, such as tin tetrachloride, tetrachlorosilane, dichlorodimethylsilane, dimethyldiethoxysilane, tetramethoxysilane, tetraethoxysilane, 3-aminopropyltriethoxysilane, tetraglycidyl-1,3-bisaminomethylcyclohexane, or 2,4-tolylenediisocyanate; a polymerization terminal modifier such as 4,4'-bis(diethylamino)benzophenone or N-vinylpyrrolidone; or other modifiers described in JP 2011-132298 A. Furthermore, the isolated copolymer can also be grafted with maleic anhydride or the like for use. The functional group may be introduced at either the polymerization terminal or the side chain of the unhydrogenated block copolymer (X0). Furthermore, the functional groups may be of one type or a combination of two or more types. The modifier is preferably used in an amount of 0.01 to 10 molar equivalents per mole of the anionic polymerization initiator.

[0068] (Hydrogenation Step) The block copolymer (X) may be converted to a hydrogenated block copolymer (X1) by subjecting the unhydrogenated block copolymer (X0) or modified block copolymer obtained by the above-described method to a hydrogenation step. Known methods can be used for the hydrogenation method. For example, the hydrogenation reaction is carried out in the presence of a hydrogenation catalyst such as a Ziegler catalyst; a nickel, platinum, palladium, ruthenium, or rhodium metal catalyst supported on carbon, silica, diatomaceous earth, or an organometallic complex containing cobalt, nickel, palladium, rhodium, or ruthenium metal, in a solution obtained by dissolving the unhydrogenated block copolymer (X0) in a solvent that does not affect the hydrogenation reaction. In the hydrogenation step, the hydrogenation reaction may be carried out by adding a hydrogenation catalyst to the polymerization reaction solution containing the unhydrogenated block copolymer (X0) obtained by the above-described production method. In this embodiment, the hydrogenation catalyst is preferably palladium carbon, in which palladium is supported on carbon. In the hydrogenation reaction, the hydrogen pressure is preferably 0.1 to 20 MPa, the reaction temperature is preferably 100 to 200°C, and the reaction time is preferably 1 to 20 hours. The hydrogenated block copolymer (X1) can be isolated by pouring the hydrogenated reaction solution obtained in the above step into a poor solvent such as methanol to precipitate the hydrogenated block copolymer (X1), or by washing the hydrogenated reaction solution with water, separating it, and then drying it. Methods for isolating the hydrogenated block copolymer (X1) include coagulating the resin component (steam stripping), and spray drying, in which a polymer solution is heated to a high temperature and high pressure and sprayed under normal pressure to extract the resin component.

[0069] As described above, the block copolymer (X) preferably consists essentially of the unhydrogenated block copolymer (X0), essentially of the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%, or essentially of both the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol%. That is, the hydrogenation rate of the block copolymer (X) is preferably 0 mol% or more and less than 50 mol%. From the viewpoint of ensuring appropriate adhesive properties while facilitating enhanced heat resistance, the hydrogenation rate of the block copolymer (X) is preferably 0 to 49 mol%, more preferably 0 to 48 mol%, and even more preferably 0 to 47 mol%. The hydrogenation rate can be adjusted to the above range by, for example, controlling the amount of hydrogenation catalyst added and the reaction time.

[0070] Examples of the carbon-carbon double bond in the conjugated diene compound unit present in the unhydrogenated block copolymer (X0) include the carbon-carbon double bond in the conjugated diene compound unit in the polymer block (B-1). When the unhydrogenated block copolymer (X0) further contains a polymer block (B-2), examples of the carbon-carbon double bond in the conjugated diene compound unit in the polymer block (B-1) and the polymer block (B-2) include the carbon-carbon double bond in the conjugated diene compound unit in the polymer block (B-1) and the polymer block (B-2). In this specification, although the polymer block (B-1) and the polymer block (B-2) in the hydrogenated block copolymer (X1) are hydrogenated, they are referred to as "polymer block (B-1)" and "polymer block (B-2)" as before hydrogenation. The hydrogenation rate is the ratio of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1). １ It can be calculated from the values ​​of both H-NMR measurements, more specifically, by the method described in the Examples.

[0071] From the viewpoint of coatability and heat resistance, the weight average molecular weight (Mw) of the unhydrogenated block copolymer (X0) is preferably 4,000 to 1,500,000, more preferably 9,000 to 1,000,000, even more preferably 30,000 to 800,000, and even more preferably 50,000 to 500,000. The molecular weight distribution (Mw / Mn) of the unhydrogenated block copolymer (X0) is preferably 1 to 6, more preferably 1 to 4, even more preferably 1 to 3, and even more preferably 1 to 2. When the molecular weight distribution is within the above range, the viscosity of the unhydrogenated block copolymer (X0) varies little, making it easy to handle.

[0072] From the viewpoint of coatability and heat resistance, the weight average molecular weight (Mw) of the hydrogenated block copolymer (X1) is preferably 4,000 to 1,500,000, more preferably 9,000 to 1,000,000, even more preferably 30,000 to 800,000, and even more preferably 50,000 to 500,000. The molecular weight distribution (Mw / Mn) of the hydrogenated block copolymer (X1) is preferably 1 to 6, more preferably 1 to 4, even more preferably 1 to 3, and even more preferably 1 to 2. When the molecular weight distribution is within the above range, the viscosity of the hydrogenated block copolymer (X1) varies little, making it easy to handle. Note that the molecular weight distribution (Mw / Mn) in this specification refers to a value measured by the method described in the Examples section below.

[0073] From the viewpoint of heat resistance, etc., the weight average molecular weight (Mw) of the block copolymer (X) is preferably 30,000 to 450,000, more preferably 35,000 to 400,000, even more preferably 40,000 to 350,000, particularly preferably 45,000 to 300,000, and most preferably 50,000 to 250,000. The weight average molecular weight of the block copolymer (X) can be adjusted to the above range by, for example, adjusting the amount of monomer relative to the polymerization initiator.

[0074] <Tackifier (Y)> A wide variety of tackifiers (Y) can be selected depending on the application and required performance of the resulting pressure-sensitive adhesive composition. The tackifier (Y) is not particularly limited, but examples thereof include rosin-based compounds such as natural rosin, polymerized rosin, modified rosin, glycerol ester of natural rosin, glycerol ester of modified rosin, pentaerythritol ester of natural rosin, pentaerythritol ester of modified rosin, hydrogenated rosin, pentaerythritol ester of hydrogenated rosin; copolymers of natural terpene, three-dimensional polymers of natural terpene, aromatic modified terpene resins, hydrogenated products of aromatic modified terpene resins and derivatives thereof, terpene phenolic resins, hydrogenated products of terpene phenolic resins and derivatives thereof, terpene resins (monoterpene, diterpene, triterpene, polyperene, etc.), hydrogenated terpene resins, hydrogenated products of hydrogenated terpene resins. Examples of petroleum hydrocarbon compounds include terpene compounds such as olefins and derivatives thereof; pinene resins; aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated aliphatic petroleum hydrocarbon resins and derivatives thereof, aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated aromatic petroleum hydrocarbon resins, derivatives of hydrogenated aromatic petroleum hydrocarbon resins, hydrogenated aromatic modified alicyclic hydrocarbon resins (DCPD-C9 resins) and / or derivatives thereof, dicyclopentadiene resins, hydrogenated dicyclopentadiene resins and derivatives thereof, C5 / C9 copolymer resins, hydrogenated C5 / C9 copolymer resins and derivatives thereof, cycloaliphatic petroleum hydrocarbon resins, and hydrogenated cycloaliphatic petroleum hydrocarbon resins and derivatives thereof; and aromatic group-containing resins. Note that a C5 / C9 copolymer is a copolymerized petroleum resin polymerized using a mixture of C5 fraction and C9 fraction as a raw material.

[0075] Commercially available hydrogenated products and derivatives thereof are not particularly limited, and include Arcon P90, Arcon P100, Arcon P115, Arcon P125, Arcon P140, Arcon M90, Arcon M100, Arcon M115, Arcon M135, Estergum H, Estergum HP, and Hyperl, all manufactured by Arakawa Chemical Co., Ltd.; and Rigalite R1010, Rigalite R1090, Rigalite R1100, Rigalite S5100, and Rigalite R1200, all manufactured by Eastman Chemical Co., Ltd. 7100, Rigalite C6100, East Tack C100W, East Tack C100L, East Tack C100R, East Tack C115W, East Tack C115R, Steperite E, Foral AXE, Steperite Ester 10E, Yasuhara Chemical Co., Ltd.'s Clearon P105, Clearon P115, Clearon P125, Clearon P135, Clearon P150, Clearon M105, Clearon M115, Clearon K100, Clearon Aron K110, Clearon K4100, Clearon K4090, YS Polystar UH, Exxon Corporation's Escoretz 5340, Escoretz 5320, Escoretz 5300, Escoretz 5380, Escoretz 5400, Escoretz 227E, Escoretz 5600, Escoretz 5690, Zeon Corporation's Quinton A100, Quinton B170, Quinton M100, Quinton R100, Quinton S195, Quinton D100, and Quinton Quinton U185, Quinton DX395, Quinton 390N, Quinton N180, Quinton G100B, Quinton G115, Quinton E200SN, Quinton D200, Quinton 1105, Quinton 1325, Quinton 1340, Idemitsu Kosan's Imave S100, Imave S110, Imave P100, Imave P125, Imave P140, Rika Finetech Co., Ltd.'s Ricarosin F, and TonenGeneral Sekiyu K.K.'s T-REZ OP501, T-REZ PR801, T-REZ HA125, T-REZ HB125.

[0076] Commercially available tackifiers other than the above-mentioned various hydrogenated products and derivatives thereof include Ester Gum AA-L, Ester Gum A, Ester Gum AAV, Ester Gum, Ester Gum 105, Ester Gum AT, Bencel A, Bencel AZ, Bencel C, Bencel D125, Bencel D160, Super Ester, Tamanor, Pine Crystal, and Aradigm, all manufactured by Arakawa Chemical Industries, Ltd. , Wingtack 10, Wingtack 95, Wingtack 98, Wingtack Extra, Wingtack RWT-7850, Wingtack PLUS, Wingtack ET, Wingtack STS, Wingtack 86, Norsolnene manufactured by Cray Valley, and Piccotac 8095 and Piccotac 109 manufactured by Eastman Chemical Company No. 5, Piccotac 1098, Piccotac 1100, Escorez 1102, Escorez 1202, Escorez 1204LS, Escorez 1304, Escorez 1310, Escorez 1315, Escorez 224, Escorez 2101, Escorez 213, Escorez 807 manufactured by ExxonMobil Chemical Company, and Sylvagum and and Sylvalite manufactured by Ashland; Piccolyte manufactured by Ashland; YS Resin PX, YS Resin PXN, YS Polystar U, YS Polystar T, YS Polystar S, YS Polystar G, YS Polystar N, YS Polystar K, YS Polystar TH, YS Resin TO, YS Resin TR, YS Resin SX manufactured by Yasuhara Chemical Co., Ltd.; and Marukarets M manufactured by Maruzen Petrochemical Co., Ltd.

[0077] The aliphatic tackifiers, such as the aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated aliphatic petroleum hydrocarbon resins (C5 resins) and derivatives thereof, C5 / C9 copolymer resins, and hydrogenated C5 / C9 copolymer resins and derivatives thereof, preferably have an aliphatic hydrocarbon group content of 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 88% by mass or more, and still more preferably 95% by mass or more. The aliphatic tackifiers can be produced by homopolymerizing or copolymerizing a monomer having an aliphatic group and a polymerizable unsaturated group.

[0078] Monomers having an aliphatic group and a polymerizable unsaturated group include, but are not limited to, natural and synthetic terpenes containing C5 or C6 cyclopentyl or cyclohexyl groups, and other monomers that can be used in copolymerization include, but are not limited to, 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene, terpenes, terpene-phenolic resins, and the like.

[0079] The aromatic tackifiers, such as the aromatic petroleum hydrocarbon resins (C9 resins) and C5 / C9 copolymer resins, preferably have an aromatic hydrocarbon group content of 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 88% by mass or more, and still more preferably 95% by mass or more. The aromatic tackifiers can be produced by homopolymerizing or copolymerizing monomers each having an aromatic group and a polymerizable unsaturated group.

[0080] Monomers having an aromatic group and a polymerizable unsaturated group include, but are not limited to, styrene, α-methylstyrene, vinyltoluene, methoxystyrene, tert-butylstyrene, chlorostyrene, and indene monomers (including methylindene). Other monomers that can be used in copolymerization include, but are not limited to, 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, 2-methyl-2-butene, cyclopentadiene, dicyclopentadiene, terpene, and terpene-phenol resins. Commercially available aromatic tackifiers include Endex 155, Crystallex 1120, Crystallex 3085, Crystallex 3100, Crystallex 5140, Crystallex F100, Plastrin 240, Plastrin 290, and Picotex 100, all manufactured by Eastman Chemical Company; and Nitto Resin Coumarone G-90, V-120, and V-120S, all manufactured by Nippon Paint Chemical Industry Co.

[0081] Tackifiers that have affinity for the glass phase blocks of block copolymers, such as resins having an aromatic ring between molecules, can also be used. Examples of such resins include, but are not limited to, aromatic group-containing resins such as homopolymers or copolymers containing vinyltoluene, styrene, α-methylstyrene, coumarone, or indene as structural units. Among these, KristAlEx and PlAstolylN (trade names, manufactured by Eastman Chemical Company), which contain α-methylstyrene, are preferred. These tackifiers can be used alone or in combination of two or more. From the viewpoint of imparting good adhesive properties to the pressure-sensitive adhesive composition, the content of the tackifier (Y) is preferably 50 to 170 parts by mass, more preferably 60 to 150 parts by mass, and even more preferably 70 to 120 parts by mass, relative to 100 parts by mass of the block copolymer (X).

[0082] <Plasticizer (Z)> The pressure-sensitive adhesive composition may contain a plasticizer (Z). When the pressure-sensitive adhesive composition contains the plasticizer (Z), the coatability and adhesive properties are improved. Examples of the plasticizer (Z) include a liquid rubber component (Za), a biomass-derived plasticizer (Zb), a synthetic plasticizer (Zc), and a vegetable oil (Zd). These are preferably plasticizers that do not have a carboxy group. These may be contained alone, or two or more may be contained in combination. In one aspect of the present invention, the pressure-sensitive adhesive composition further contains at least one selected from the group consisting of a liquid rubber component (Za), a biomass-derived plasticizer (Zb), and a synthetic plasticizer (Zc).

[0083] (Liquid Rubber Component (Za)) The liquid rubber component (Za) contained in the pressure-sensitive adhesive composition is a synthetic rubber having a melt viscosity at 38°C (hereinafter also referred to as "38°C melt viscosity") of 2,000 Pa s or less. The 38°C melt viscosity of the liquid rubber component (Za) can be measured using a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.). The liquid rubber component (Za) may be a non-hydrogenated liquid rubber or a hydrogenated liquid rubber. In this specification, "liquid rubber component (Za)" includes a liquid rubber before hydrogenation (hereinafter sometimes referred to as unhydrogenated liquid rubber (Za0)) and a liquid rubber obtained by hydrogenating the unhydrogenated liquid rubber (Za0) (hereinafter sometimes referred to as hydrogenated liquid rubber (Za1)). The liquid rubber component (Za) may contain both the unhydrogenated liquid rubber (Za0) and the hydrogenated liquid rubber (Za1). The liquid rubber component (Za) will be described below, but unless otherwise specified, this description applies to both the unhydrogenated liquid rubber (Za0) and the hydrogenated liquid rubber (Za1).

[0084] Examples of the liquid rubber component (Za) include liquid diene-based rubbers such as liquid polyfarnesene rubber, liquid isoprene rubber, liquid butadiene rubber, and liquid styrene butadiene rubber. Among these, from the viewpoint of the balance between the melt viscosity at 38°C and the flexibility of the adhesive composition, liquid polyfarnesene rubber and liquid butadiene rubber are preferred, and liquid polyfarnesene rubber is more preferred. The liquid diene-based rubber may contain other monomer units such as conjugated diene compound units other than β-farnesene, isoprene, and butadiene, and aromatic vinyl compound units. The liquid diene-based rubber is a polymer containing at least one of β-farnesene, isoprene, and butadiene units in an amount of 50% by mass or more relative to the total monomer units constituting the polymer. The total content of the β-farnesene units, isoprene units and butadiene units is preferably 60% by mass or more and 100% by mass or less, and more preferably 70% by mass or more and 100% by mass or less, based on the total monomer units constituting the liquid diene rubber.

[0085] The liquid rubber component (Za) can be prepared by a known method, for example, by polymerizing at least one selected from the group consisting of β-farnesene, isoprene, and butadiene, and a monomer added as needed, by a method such as emulsion polymerization or solution polymerization, etc. Among these, the solution polymerization method is particularly preferred.

[0086] Furthermore, the hydrogenated liquid rubber (Za1) can be obtained by hydrogenating the polymerized monomers (i.e., the unhydrogenated liquid rubber (Za0)) in the same manner as in the production method of the hydrogenated block copolymer (X1) described above.

[0087]

[0044] From the viewpoints of compatibility with the block copolymer (X), adhesive properties, and heat resistance, the above-mentioned pressure-sensitive adhesive composition preferably further contains a liquid rubber component (Za), and the liquid rubber component (Za) preferably contains at least one selected from the group consisting of an unhydrogenated liquid rubber (Za0) that is a liquid rubber that has not been hydrogenated, and a hydrogenated liquid rubber (Za1) that is a hydrogenated liquid rubber having a hydrogenation rate of 90 mol% or less.

[0088] The liquid rubber component (Za) is preferably composed essentially of unhydrogenated liquid rubber (Za0) alone, or essentially of hydrogenated liquid rubber (Za1) having a hydrogenation rate of 90 mol% or less, or essentially of both unhydrogenated liquid rubber (Za0) and hydrogenated liquid rubber (Za1) having a hydrogenation rate of 90 mol% or less, and more preferably composed essentially of unhydrogenated liquid rubber (Za0). Here, "substantially" means that in addition to an embodiment consisting solely of the unhydrogenated liquid rubber (Za0) and an embodiment consisting solely of the hydrogenated liquid rubber (Za1), it may also be composed of an embodiment containing components such as hydrogenated liquid rubber having a hydrogenation rate of more than 90 mol%, which are inevitably present in the process of producing the liquid rubber component.

[0089] In the pressure-sensitive adhesive composition, the content of the liquid rubber component (Za) is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, still more preferably 30 parts by mass or more, even more preferably 31 parts by mass or more, still more preferably 40 parts by mass or more, even more preferably 46 parts by mass or more, still more preferably 50 parts by mass or more, and particularly preferably 51 parts by mass or more, relative to 100 parts by mass of the block copolymer (X), and from the viewpoint of suppressing bleeding, is preferably 300 parts by mass or less, more preferably 270 parts by mass or less, even more preferably 250 parts by mass or less, and still more preferably 230 parts by mass or less. In other words, the content of the liquid rubber component (Za) is preferably 10 to 300 parts by mass relative to 100 parts by mass of the block copolymer (X).

[0090] From the viewpoints of dispersibility and heat resistance, the weight average molecular weight of the liquid rubber component (Za) is preferably 2,000 to 30,000, more preferably 2,500 to 25,000, even more preferably 3,000 to 20,000, still more preferably 3,500 to 17,000, and particularly preferably 4,000 to 15,000. The weight average molecular weight of the liquid rubber component (Za) can be adjusted to the above range, for example, by adjusting the amount of the conjugated diene compound relative to the polymerization initiator used in the polymerization.

[0091] From the viewpoint of ensuring dispersibility and adhesiveness in the block copolymer (X), the melt viscosity at 38°C of the liquid rubber component (Za) is preferably 0.1 to 1,000 Pa s, more preferably 0.2 to 500 Pa s, even more preferably 0.3 to 300 Pa s, and still more preferably 0.3 to 100 Pa s. The melt viscosity at 38°C of the liquid rubber component (Za) can be adjusted to the above range, for example, by adjusting the type of conjugated diene compound used or the hydrogenation rate of the polymer thereof, or by adjusting the weight average molecular weight of the liquid rubber component (Za) used.

[0092] The weight average molecular weight (Mw) of the unhydrogenated liquid rubber (Za0) is preferably 3,000 to 200,000, more preferably 4,000 to 100,000, even more preferably 5,000 to 50,000, and even more preferably 8,000 to 15,000, from the viewpoint of adhesiveness. The molecular weight distribution (Mw / Mn) of the unhydrogenated liquid rubber (Za0) is preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, and even more preferably 1 to 2. When the molecular weight distribution is within the above range, the viscosity of the unhydrogenated liquid rubber (Za0) varies little, making it easy to handle. From the viewpoint of adhesive properties, the weight average molecular weight (Mw) of the hydrogenated liquid rubber (Za1) is preferably 3,000 to 300,000, more preferably 5,000 to 250,000, even more preferably 10,000 to 200,000, and even more preferably 15,000 to 150,000. The molecular weight distribution (Mw / Mn) of the hydrogenated liquid rubber (Za1) is preferably 1 to 5, more preferably 1 to 4, even more preferably 1 to 3, and even more preferably 1 to 2. When the molecular weight distribution is within the above range, the viscosity of the hydrogenated liquid rubber (Za1) varies little, making it easy to handle.

[0093] (Biomass-derived plasticizer (Zb)) The pressure-sensitive adhesive composition may contain a biomass-derived plasticizer (Zb). From the viewpoint of oil bleeding, the biomass-derived plasticizer (Zb) is preferably a biomass-derived plasticizer having no carboxy group. Specific preferred examples of the biomass-derived plasticizer (Zb) include compounds represented by the following general formula (1) and compounds represented by the following general formula (2). These may be used alone or in combination of two or more.

[0094] However, in the general formula (1), n １ ~n ３ are each independently 1 or 3, and R １ ~R ６ are each independently a hydrogen atom or an unsubstituted hydrocarbon group, and R １ and R ２ The total number of carbon atoms in R is 14, ３ and R ４ The total number of carbon atoms in R is 14, ５ and R ６ The total number of carbon atoms in R is 14, １ ~R ６ may have a branched structure.

[0095] In the general formula (2), n ４ and n ５ are each independently 1 or 3, and R ７ ~R １０ are each independently a hydrogen atom or an unsubstituted hydrocarbon group, and R ７ and R ８ The total number of carbon atoms in R is 14, ９ and R １０ The total number of carbon atoms in R is 14, ７ ~R １０ may have a branched structure.

[0096] (Specific Examples of Compounds Represented by General Formula (1)) Specific examples of compounds represented by general formula (1) include compounds represented by the following structural formulas (1-1) to (1-8).

[0097] (The compound represented by structural formula (1-1) is a compound represented by general formula (1), R １ = H, R ２ =C １４ H ２９ , R ３ =C １４ H ２９ , R ４ = H, R ５ = H, R ６ =C １４ H ２９ , n １ = 1, n ２ = 1, n ３ = 1 compound.)

[0098] (The compound represented by structural formula (1-2) is a compound represented by general formula (1), R １ = H, R ２ =C １４ H ２９ , R ３ =C １４ H ２９ (branch), R ４ = H, R ５ = H, R ６ =C １４ H ２９ (branch), n １ = 1, n ２ = 1, n ３ = 1 compound.)

[0099] (The compound represented by structural formula (1-3) is a compound represented by general formula (1), R １ = H, R ２ =C １４ H ２９ (branch), R ３ =C １０ H ２１ , R ４ =C ４ H ９ , R ５ = H, R ６ =C １４ H ２９ , n １ = 3, n ２ = 1, n ３ = 1 compound.)

[0100]

[0101] (The compound represented by structural formula (1-4) is a compound represented by general formula (1), R １ = H, R ２ =C １４ H ２９ (branch), R ３ =C １１ H ２３ (branch), R ４ =C ３ H ７ , R ５ =C ３ H ７ , R ６ =C １１ H ２３ , n １ = 3, n ２ = 1, n ３ = 1 compound.) (The compound represented by structural formula (1-5) is a compound represented by general formula (1), R １ =C ６ H １３ , R ２ =C ８ H １７ , R ３ =C ３ H ７ , R ４ =C １１ H ２３ (branch), R ５ =C ９ H １９ , R ６ =C ５ H １１ , n １ = 1, n ２ = 3, n ３ = 1 compound.)

[0102] (The compound represented by structural formula (1-6) is a compound represented by general formula (1), R １ = H, R ２ =C １４ H ２９ , R ３ =C ３ H ７ , R ４ =C １１ H ２３ (branch), R ５ =C １１ H ２３ (branch), R ６ =C ３ H７ , n １ = 3, n ２ = 3, n ３ = 3 compound.)

[0103] (The compound represented by structural formula (1-7) is a compound represented by general formula (1), R １ =C １０ H ２１ , R ２ =C ４ H ９ , R ３ =C ３ H ７ , R ４ =C １１ H ２３ , R ５ =C １１ H ２３ , R ６ =C ３ H ７ , n １ = 3, n ２ = 3, n ３ = 3 compound.)

[0104] (The compound represented by structural formula (1-8) is a compound represented by general formula (1), R １ =C ９ H １９ (branch), R ２ =C ５ H １１ , R ３ =C ５ H １１ , R ４ =C ９ H １９ , R ５ =C ９ H １９ , R ６ =C ５ H １１ , n １ = 3, n ２ = 3, n ３ = 3 compound.)

[0105] (Specific Examples of Compounds Represented by General Formula (2)) Specific examples of compounds represented by general formula (2) include compounds represented by the following structural formulas (2-1) to (2-8).

[0106] (The compound represented by structural formula (2-1) is a compound represented by general formula (2), R ７ =C １４ H ２９ , R ８ = H, R ９ =C １４ H ２９ , R １０ = H, n ４ = 1, n ５ = 1 compound.)

[0107] (The compound represented by structural formula (2-2) is a compound represented by general formula (2), R ７ =C １４ H ２９ (branch), R ８ = H, R ９ =C １４ H ２９ (branch), R １０ = H, n ４ = 1, n ５ = 1 compound.)

[0108] (The compound represented by structural formula (2-3) is a compound represented by general formula (2), R ７ =C １４ H ２９ , R ８ = H, R ９ =C １０ H ２１ , R １０ =C ４ H ９ , n ４ = 1, n ５ = 1 compound.)

[0109]

[0110] (The compound represented by structural formula (2-4) is a compound represented by general formula (2), R ７ =C １１ H ２３ , R ８ =C ３ H ７ , R ９ =C １１ H ２３ (branch), R １０ =C ３ H ７ , n ４ = 1, n ５= 1 compound.) (The compound represented by structural formula (2-5) is a compound represented by general formula (2), R ７ =C ５ H １１ , R ８ =C ９ H １９ , R ９ =C ３ H ７ , R １０ =C １１ H ２３ (branch), n ４ = 1, n ５ = 3 compound.)

[0111] (The compound represented by structural formula (2-6) is a compound represented by general formula (2), R ７ =C ３ H ７ , R ８ =C １１ H ２３ (branch), R ９ =C ３ H ７ , R １０ =C １１ H ２３ (branch), n ４ = 3, n ５ = 3 compound.)

[0112] (The compound represented by structural formula (2-7) is a compound represented by general formula (2), R ７ =C ３ H ７ , R ８ =C １１ H ２３ , R ９ =C ３ H ７ , R １０ =C １１ H ２３ , n ４ = 3, n ５ = 3 compound.)

[0113] (The compound represented by structural formula (2-8) is a compound represented by general formula (2), R ７ =C ５ H １１ , R ８ =C ９ H１９ , R ９ =C ５ H １１ , R １０ =C ９ H １９ , n ４ = 3, n ５ = 3 compound.)

[0114] An example of a product of the biomass-derived plasticizer (Zb) is VIVA-B-FIX10227, manufactured by H&R (a mixture having a structure represented by the above general formula (1), biobased content (ASTM D6866-21): 100% by mass). In order to easily ensure appropriate adhesive properties and from the viewpoint of coatability, the content of the biomass-derived plasticizer (Zb) in the pressure-sensitive adhesive composition is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and is also preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less. In other words, the content of the biomass-derived plasticizer (Zb) in the pressure-sensitive adhesive composition is preferably 3 to 40% by mass. When the total amount of the biomass-derived plasticizer (Zb) and other plasticizers is 100 parts by mass, the content of the biomass-derived plasticizer (Zb) is preferably 40 parts by mass or more, more preferably 60 parts by mass or more, even more preferably 80 parts by mass or more, even more preferably 90 parts by mass or more, particularly preferably 95 parts by mass or more, and most preferably 100 parts by mass.

[0115] The biobased content of the biomass-derived plasticizer (Zb) is not particularly limited, but from the viewpoint of further reducing the environmental load, it is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 85% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and most preferably 100% by mass.

[0116] The kinematic viscosity of the biomass-derived plasticizer (Zb) at 40° C. is not particularly limited, but is preferably 100 cSt or less, more preferably 80 cSt or less, and even more preferably 60 cSt or less.

[0117] The melting point of the biomass-derived plasticizer (Zb) is not particularly limited, but is preferably −70° C. or higher, more preferably −60° C. or higher, even more preferably −50° C. or higher, and is preferably 20° C. or lower, more preferably 10° C. or lower, even more preferably 0° C. or lower.

[0118] (Synthetic Plasticizer (Zc)) Examples of the synthetic plasticizer (Zc) include oil-based softeners such as paraffinic, naphthenic, and aromatic process oils, mineral oil, and white oil; phthalic acid derivatives such as dioctyl phthalate and dibutyl phthalate; liquid co-oligomers of ethylene and α-olefins; liquid paraffin; polybutene; low-molecular-weight polyisobutylene; liquid polydienes such as liquid polybutadiene, liquid polyisoprene, liquid polyisoprene / butadiene copolymer, liquid styrene / butadiene copolymer, and liquid styrene / isoprene copolymer; and hydrogenated or modified products thereof. These may be used alone or in combination of two or more.

[0119] Among these, from the viewpoint of compatibility with the block copolymer (X), paraffinic and naphthenic process oils; liquid co-oligomers of ethylene and α-olefins; liquid paraffin; and low-molecular-weight polyisobutylene are preferred, and paraffinic and naphthenic process oils are more preferred.

[0120]

[0047] From the viewpoints of easily ensuring appropriate adhesive properties and coatability, the content of the synthetic plasticizer (Zc) in the pressure-sensitive adhesive composition is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less. In other words, the content of the synthetic plasticizer (Zc) in the pressure-sensitive adhesive composition is preferably 3 to 40% by mass.

[0121] (Vegetable Oil (Zd)) Examples of the vegetable oil (Zd) include plant-derived oils and fats such as castor oil, cottonseed oil, linseed oil, safflower oil, rapeseed oil, soybean oil, safflower oil, Japan wax, pine oil, corn oil, peanut oil, olive oil, palm oil, palm olein, and palm stearin, as well as interesterified oils, hydrogenated oils, and fractionated oils thereof. These may be used alone or in combination of two or more. Among these, from the viewpoint of compatibility with the block copolymer (X), crude palm oil, refined palm oil, crude palm stearin, refined palm stearin, crude palm olein, refined palm olein, and hydrogenated products thereof are preferred, and hydrogenated products of refined palm stearin are more preferred.

[0122] The biobased content of the vegetable oil (Zd) is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, still more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0123]

[0044] From the viewpoints of easily ensuring appropriate adhesive properties and coatability, the content of the vegetable oil (Zd) in the pressure-sensitive adhesive composition is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and is preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less. In other words, the content of the vegetable oil (Zd) in the pressure-sensitive adhesive composition is preferably 3 to 40% by mass.

[0124] <Other Components> The pressure-sensitive adhesive composition may contain components other than the block copolymer (X), tackifier (Y), and plasticizer (Z). Examples of such components include antioxidants, crosslinking agents, photoradical polymerization initiators, heat aging inhibitors, light stabilizers, antistatic agents, release agents, flame retardants, foaming agents, pigments, dyes, and brighteners. The pressure-sensitive adhesive composition may also contain a solvent as described in the "Method for producing pressure-sensitive adhesive composition" section below. Representative other components will be described below.

[0125] (Antioxidant) Examples of the antioxidant include hindered phenol-based antioxidants, phosphorus-based antioxidants, hydroxylamine-based antioxidants, hindered phenol / phosphorus mixed antioxidants, and oxygen absorbers.

[0126] Examples of hindered phenol antioxidants include IRGANOX 1010 (manufactured by BASF), Adeka Stab AO-60 (manufactured by ADEKA Corporation), Sumilizer BP-101 (manufactured by Sumitomo Chemical Co., Ltd.) (pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]), IRGANOX 1035 (manufactured by BASF) (2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]), and IRGANOX 1076 (manufactured by BASF) (octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate). butyl-4-hydroxyphenyl)propionate), IRGANOX 1098 (manufactured by BASF) (N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide)), IRGANOX 1135 (manufactured by BASF) (isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate), IRGANOX 1330 (manufactured by BASF) (1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene), IRGANOX 1726 (manufactured by BASF) (4,6-bis( ... (dodecylthiomethyl)-o-cresol), IRGANOX 1425 (manufactured by BASF) (bis(3,5-di-t-butyl-4-hydroxybenzylphosphonate ethyl) calcium (50%), polyethylene wax (50%)), IRGANOX 1520 (manufactured by BASF) (2,4-bis[(octylthio)methyl]-o-cresol), IRGANOX 245 (manufactured by BASF) (triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate]), IRGANOX 259 (manufactured by BASF) (1,6-hexyl xanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]), IRGANOX 3114 (manufactured by BASF) (tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate), IRGANOX 5057 (manufactured by BASF) (octylated diphenylamine), IRGANOX 565 (manufactured by BASF) (2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine), Cyanox CY1790 (manufactured by Sun Chemical Co., Ltd.) (1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid), Adekastab AO-40 (manufactured by ADEKA Corporation), Sumilizer BBM (manufactured by Sumitomo Chemical Co., Ltd.) (4,4'-butylidenebis(3-methyl-6-t-butylphenol)), Adekastab AO-50 (manufactured by ADEKA Corporation), Sumilizer BP-76 (manufactured by Sumitomo Chemical Co., Ltd.) (stearyl-β-(3 ,5-di-t-butyl-4-hydroxyphenyl)propionate), Adekastab AO-80 (manufactured by ADEKA Corporation), Sumilizer GA-80 (manufactured by Sumitomo Chemical Co., Ltd.) (3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]-undecane).

[0127] Examples of phosphorus-based antioxidants include IRGAFOS12 (manufactured by BASF, molecular weight 1462.9) (6,6',6''-[nitrilotris(ethyleneoxy)]tris(2,4,8,10-tetra-tert-butylbenzo[d,f][1,3,2]dioxaphosphepine)), IRGAFOS38 (manufactured by BASF, molecular weight 514) (ethyl bis(2,4-di-tert-butyl-6-methylphenyl) phosphite), and IRGAFOS168 (manufactured by BASF, molecular weight 646 ), ADK STAB 2112 (manufactured by ADEKA CORPORATION), SUMIRAIZER P-16 (manufactured by Sumitomo Chemical Co., Ltd.) (tris(2,4-di-t-butylphenyl)phosphite), ADK STAB PEP-8 (manufactured by ADEKA CORPORATION) (distearyl pentaerythritol diphosphite), ADK STAB PEP-36 (manufactured by ADEKA CORPORATION) (cyclic neopentanetetraylbis(2,6-di-t-butyl-4-methylphenyl)phosphite), and the like.

[0128] An example of the hydroxylamine-based antioxidant is IRGASTAB FS 042 (manufactured by BASF) (N,N-dioctadecylhydroxylamine).

[0129] Examples of the hindered phenol / phosphorus mixed antioxidant include IRGANOX B 225 (manufactured by BASF) (IRGAFOS168:IRGANOX1010=1:1), IRGANOX215 (manufactured by BASF) (IRGAFOS168:IRGANOX1010=2:1), IRGANOX220 ​​(manufactured by BASF) (IRGAFOS168:IRGANOX1010=3:1), and IRGANOX921 (manufactured by BASF) (IRGAFOS168:IRGANOX1076=2:1).

[0130] The oxygen absorber may be, for example, an iron powder oxygen absorber. Typically, the iron powder oxygen absorber has a surface area of ​​0.5 m ２ For 100 parts by weight of iron powder having a saturation of 1 / g or more, 0.1 to 50 parts by weight of a metal halide, for example, a halide of an alkali metal or alkaline earth metal such as sodium chloride, sodium bromide, calcium chloride, or magnesium chloride, such as chlorine, bromine, or iodine, is used in combination. A mixture of the two may be used, or the surface of the iron powder may be coated with a metal halide. The oxygen absorber used in the present invention may be further combined with porous particles such as zeolite impregnated with water to further promote the oxidation of iron by oxygen.

[0131] The content of the antioxidant is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 7 parts by mass, and even more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the total of the block copolymer (X), the tackifier resin (Y), and the plasticizer (Z).

[0132] (Crosslinking Agent) When the pressure-sensitive adhesive composition contains a crosslinking agent, the heat resistance of the pressure-sensitive adhesive composition can be further improved by crosslinking at least the block copolymer (X) with the crosslinking agent. Furthermore, when the pressure-sensitive adhesive composition contains a crosslinking agent and a photoradical polymerization initiator, the pressure-sensitive adhesive property of the pressure-sensitive adhesive composition can be reduced by irradiation with light such as UV light, and the pressure-sensitive adhesive composition can be preferably used for applications and pressure-sensitive adhesive products that require the property of being releasable from an adherend when temporary fixation of the adherend is no longer necessary, such as dicing tape for temporary fixation of semiconductor wafers. The crosslinking agent is preferably a polythiol derived from mercaptocarboxylic acid, more preferably a polythiol derived from 3-mercaptopropionic acid. The polythiol (B) preferably has a plurality of mercaptoacyloxy groups in the molecule, more preferably 2 to 6 mercaptoacyloxy groups. Here, specific examples of the mercaptoacyloxy group include a 3-mercaptopropionyloxy group [HS-(CH ２ ) ２ —COO—], 3-mercaptobutyloxy group [HS—CH(CH ３ )-CH ２ When the mercaptocarboxylic acid-derived polythiol (B) is blended with, for example, a photoradical polymerization initiator, a thiyl radical is generated by the radical derived from the photoradical polymerization initiator, and the thiyl radical is added to the unsaturated bond of the allyl ether group and / or vinyl ether, thereby accelerating the curing (crosslinking) reaction.

[0133] Specific examples of the polythiol (B) include tetraethylene glycol bis(3-mercaptopropionate) represented by the following chemical formula (I), trimethylolpropane tris(3-mercaptopropionate) represented by the following chemical formula (II), tris[(3-mercaptopropionyloxy)-ethyl]isocyanurate represented by the following chemical formula (III), pentaerythritol tetrakis(3-mercaptopropionate) represented by the following chemical formula (IV), dipentaerythritol hexakis(3-mercaptopropionate) represented by the following chemical formula (V), 1,4-bis(3-mercaptobutyryloxy)butane represented by the following chemical formula (VI), pentaerythritol tetrakis(3-mercaptobutyrate) represented by the following chemical formula (VII), and tetramethylolpropane tris(3-mercaptobutyrate) represented by the following chemical formula (VII). 1,3,5-tris(3-mercaptobutyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione represented by formula (VIII), 1,4-bis(3-mercaptobutyryloxy)butane represented by formula (IX) below, pentaerythritol tetrakis(3-mercaptobutyrate) represented by formula (X) below, 1,3,5-tris(2-(3-sulfanylbutanoyloxy)ethyl)-1,3,5-triazinane-2,4,6-trione represented by formula (XI) below, trimethylolpropane tris(3-mercaptobutyrate) represented by formula (XII) below, 1,4-butanediol bis(3-mercaptopropionate) represented by formula (XIII) below, and tris(mercaptoacetic acid)trimethylolpropane represented by formula (XIIV) below are preferred. These polythiols (B) may be used singly or in combination of two or more.

[0134]

[0135]

[0136]

[0137]

[0138] The pressure-sensitive adhesive composition may contain a monomer having a radically polymerizable carbon-carbon double bond as a crosslinking agent. The term "monomer having a radically polymerizable carbon-carbon double bond" refers to a monomer that can be polymerized by generating radicals when exposed to active energy rays or heat using the aforementioned photoradical polymerization initiator. Examples of monomers having a radically polymerizable carbon-carbon double bond include monosubstituted vinyl compounds such as styrene, acrylate, acrylamide, acrylonitrile, vinyl acetate, and vinyl chloride; 1,1-disubstituted vinyl compounds such as α-methylstyrene, methacrylate, and methacrylamide; cyclic olefins such as acenaphthylene and N-substituted maleimides; and conjugated diene compounds such as butadiene and isoprene. Among these, (meth)acrylates are preferred, and monofunctional (meth)acrylates, bifunctional (meth)acrylates, and trifunctional or higher polyfunctional (meth)acrylates can be used. Hereinafter, acrylates, which are monomers having a radically polymerizable carbon-carbon double bond, may be referred to as "acrylic crosslinking agents."

[0139] Examples of monofunctional (meth)acrylates include alkyl mono(meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate; cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and isobornyl (meth)acrylate; alicyclic mono(meth)acrylates such as dicyclopentenyl (meth)acrylate and dicyclopentenyloxyethyl (meth)acrylate; dicyclopentenyl group-containing mono(meth)acrylates such as phenyl acrylate and benzyl acrylate; phenoxy group-containing mono(meth)acrylates such as phenoxyhydroxypropyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate and phenoxypolyethylene glycol (meth)acrylate; alkoxyalkyl mono(meth)acrylates such as 2-butoxyethyl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and butoxyhydroxypropyl (meth)acrylate; amino group-containing (meth)acrylates such as N,N-diethylaminoethyl (meth)acrylate and N,N-dimethylaminoethyl (meth)acrylate; epoxy compounds such as glycidyl (meth)acrylate alkoxy group-containing (meth)acrylates; alkoxydialkylene glycol mono(meth)acrylates such as methoxydiethylene glycol (meth)acrylate and methoxydipropylene glycol (meth)acrylate; fluorine group-containing (meth)acrylates such as tetrafluoropropyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate; nonylphenoxy polyethylene glycol (meth)acrylate, nonylphenoxy polypropylene glycol (meth)acrylate, morpholine (meth)acrylate, and the like.

[0140] Examples of bifunctional (meth)acrylates include alkylene glycol di(meth)acrylates such as 1,4-butanediol di(meth)acrylate, neopentyl glycol diacrylate, 1,6-hexanediol di(meth)acrylate (also known as "1,6-bis(acryloyloxy)hexane") and 1,9-nonanediol di(meth)acrylate; polyalkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate and tripropylene glycol di(meth)acrylate; di(meth)acrylates having an ester group-containing diol skeleton, such as hydroxypivalic acid ester neopentyl glycol di(meth)acrylate; alicyclic di(meth)acrylates, such as dicyclopentanyl di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and ethoxylated hydrogenated bisphenol A di(meth)acrylate; hydroxypropyl di(meth)acrylate, diethylene glycol bis(hydroxypropyl(meth)acrylate), and propoxylated bisphenol A bis(hydroxyfluoropropyl(meth)acrylate).

[0141] Examples of the tri- or higher functional polyfunctional (meth)acrylate include trimethylolpropane-type polyfunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and hydroxypropylated trimethylolpropane tri(meth)acrylate; pentaerythritol-type polyfunctional (meth)acrylates such as pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and monohydroxypentaerythritol tri(meth)acrylate; and isocyanurate-type polyfunctional (meth)acrylates such as tris((meth)acryloxyethyl)isocyanurate.

[0142] The content of the crosslinking agent is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 7 parts by mass, and even more preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the total of the block copolymer (X), the tackifier resin (Y), and the plasticizer (Z).

[0143] (Photoradical Polymerization Initiator) As the photoradical polymerization initiator, an intramolecular cleavage type photoradical polymerization initiator and / or a hydrogen abstraction type photoradical polymerization initiator can be used. Examples of the intramolecular cleavage type photoradical polymerization initiator include benzoin derivatives, benzil ketals [e.g., Fujifilm Wako Pure Chemical Industries, Ltd., trade name: Irgacure 651 (2,2-dimethoxy-1,2-diphenylethan-1-one)], α-hydroxyacetophenones [e.g., Fujifilm Wako Pure Chemical Industries, Ltd., trade name: Darocur 1173 (2-hydroxy-2-methyl-1-phenylpropan-1-one), Irgacure 184 (1-hydroxycyclohexyl phenyl ketone), Irgacure 127 (2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methyl-1-one), and Irgacure 2959 (1-[4-(2-hydroxyethoxy)-phenyl] -2-hydroxy-2-methyl-1-propan-1-one)], α-aminoacetophenones [for example, Fujifilm Wako Pure Chemical Industries, Ltd., trade name: Irgacure 907 (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one), Irgacure 369 (2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1)], combinations of α-aminoacetophenones with thioxanthones (for example, isopropylthioxanthone, diethylthioxanthone), acylphosphine oxides [for example, Fujifilm Wako Pure Chemical Industries, Ltd., trade name: Irgacure 819 (bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide)], and the like.

[0144] Examples of hydrogen abstraction type photoradical polymerization initiators include a combination of benzophenones and amines, and a combination of thioxanthone and amines. An intramolecular cleavage type and a hydrogen abstraction type may also be used in combination. Among these, oligomerized α-hydroxyacetophenone and acrylated benzophenones are preferred. More specific examples include oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] [e.g., Lamberti S.p.A., trade name: ESACUREKIP150, etc.], acrylated benzophenone [e.g., Daicel U.C.B., trade name: Ebecryl P136, etc.], and imide acrylate.

[0145] In addition to these, 1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, a mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2,4,6-trimethylbenzoylphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphenylethoxyphosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-methyl-1-[(4-methylthio)phenyl] [4-(methylphenylthio)phenyl]-2-morpholinopropan-1-one, benzoyl methyl ether, benzoyl ethyl ether, benzoyl butyl ether, benzoyl isopropyl ether, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-[4-(1-methylvinyl)phenyl]propanol oligomer, a mixture of 2-hydroxy-2-methyl-[4-(1-methylvinyl)phenyl]propanol oligomer and 2-hydroxy-2-methyl-1-phenyl-1-propanone, isopropylthioxanthone, methyl o-benzoylbenzoate, and [4-(methylphenylthio)phenyl]phenylmethane can also be used.

[0146]

[0047] The amount of the photoradical polymerization initiator contained in the pressure-sensitive adhesive composition is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 3 parts by mass, relative to 100 parts by mass in total of the block copolymer (X), tackifier resin (Y), and plasticizer (Z) contained in the pressure-sensitive adhesive composition. In addition, a known photosensitizer can also be used in combination with the photoradical polymerization initiator.

[0147]

[0043] <Physical Properties of Pressure-sensitive Adhesive Composition> (Bio-based Degree) From the viewpoint of reducing petroleum-derived raw materials and ease of production, the bio-based degree of the pressure-sensitive adhesive composition, measured in accordance with ASTM D6866-21, is preferably 10 to 100 mass%, more preferably 10 to 90 mass%, even more preferably 13 to 85 mass%, still more preferably 15 to 80 mass%, still more preferably 17 to 78 mass%, still more preferably 19 to 76 mass%, still more preferably 25 to 74 mass%, still more preferably 30 to 72 mass%, still more preferably 35 to 70 mass%, and particularly preferably 38 to 70 mass%. The bio-based degree is measured in detail by the method described in the Examples.

[0148] (Haze) According to the pressure-sensitive adhesive composition, the haze, which is an index correlated with compatibility, can be reduced, and for example, it is possible to make it 35% or less, 10% or less, or 5% or less. The haze is measured in accordance with JIS K 7136:2000, and in detail, is measured by the method described in the Examples.

[0149] (180° Peel Strength) The 180° peel strength of the pressure-sensitive adhesive composition, measured in accordance with JIS Z 0237:2009 at a temperature of 23°C and a peel speed of 200 mm / min, is preferably 10.0 N / 25 mm or more, more preferably 15.0 N / 25 mm or more, and even more preferably 20.0 N / 25 mm or more, from the viewpoint of ensuring high pressure-sensitive adhesive properties. In the case of applications requiring relatively low pressure-sensitive adhesive properties, from the viewpoint of ensuring the minimum necessary pressure-sensitive adhesive properties while easily preventing the occurrence of adhesive residue, it is preferably 2.0 to 9.5 N / 25 mm, more preferably 3.0 to 9.0 N / 25 mm, even more preferably 3.5 to 8.5 N / 25 mm, and still more preferably 4.0 to 8.0 N / 25 mm. The 180° peel strength is measured in detail by the method described in the Examples.

[0150] (SAFT) The adhesive composition has a cross-sectional fracture temperature (SAFT) calculated from the weight drop time under the conditions of an adhesive area of ​​25 mm x 25 mm, a weight of 500 g, a temperature range of 40 to 205°C, and a heating rate of 0.5°C / min in accordance with ASTM D3654M:2019, which is preferably 95°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher, from the viewpoint of ensuring sufficient heat resistance. When higher heat resistance is required, the SAFT is preferably 130°C or higher, more preferably 150°C or higher, even more preferably 180°C or higher, still more preferably 200°C or higher, still more preferably 205°C or higher, and particularly preferably higher than 205°C. The SAFT is measured in detail by a method described in the Examples.

[0151] (Melt Viscosity Measured at 180°C) From the viewpoint of processability and ease of application as a hot-melt adhesive composition, the melt viscosity of the adhesive composition measured at 180°C is preferably 16,000 mPa s or less, more preferably 15,000 mPa s or less, even more preferably 14,500 mPa s or less, and still more preferably 14,000 Pa s or less. From the viewpoint of ease of handling as a hot-melt adhesive composition, the melt viscosity is preferably 1,000 mPa s or more, more preferably 1,500 mPa s or more, even more preferably 1,800 mPa s or more, and still more preferably 2,000 mPa s or more. In other words, the melt viscosity of the adhesive composition measured at 180°C is preferably 1,000 to 16,000 mPa s. The melt viscosity of the adhesive composition means the viscosity measured at 180°C using a Brookfield viscometer (B-type viscometer).

[0152] [Method for producing pressure-sensitive adhesive composition] A method for producing a pressure-sensitive adhesive composition according to an embodiment of the present invention comprises: (I) a step of dissolving the block copolymer (X) and the tackifier (Y) in a solvent and then distilling off the solvent; or (II) a step of melt-kneading the block copolymer (X) and the tackifier (Y).

[0153] The above-mentioned production method (I) (hereinafter also referred to as "production method (I)") preferably comprises the steps of: preparing a mixed solution by mixing a solution (X') containing a block copolymer (X) and a first solvent, and a solution (Y') containing a tackifier (Y) and a second solvent (step 1-1); and obtaining a resin component by removing the first and second solvents contained in the mixed solution (step 1-2). Examples of the first solvent and the second solvent include cyclopentane, cyclohexane, cycloheptane, and cyclooctane. The first solvent and the second solvent may be the same or different. In production method (I), the use of a solvent reduces the constraints on the viscosity of the usable tackifier (Y). This allows for a greater degree of freedom in the design of the pressure-sensitive adhesive composition. Furthermore, it becomes easier to use a tackifier (Y) with a high viscosity, which makes it easier to improve the physical properties, such as the adhesion retention, of the pressure-sensitive adhesive composition.

[0154] In the production method (I), the block copolymer (X) and the tackifier (Y) may be added simultaneously to a common solvent, or the block copolymer (X) may be added to a solvent and then the tackifier (Y) may be added to the solvent, or the tackifier (Y) may be added to a solvent and then the block copolymer (X) may be added to the solvent. Alternatively, the block copolymer (X) and the tackifier (Y) may be melt-kneaded in advance to prepare a mixture, which may then be dissolved in a solvent. When the plasticizer (Z) is used, it is preferable to dissolve the block copolymer (X), the tackifier (Y), and the plasticizer (Z) in a solvent. Alternatively, any two of the block copolymer (X), the tackifier (Y), and the plasticizer (Z) may be mixed first, the mixture may be dissolved in a solvent, and the remaining component may be dissolved in the resulting solution. Alternatively, the mixture may be dissolved in a first solvent, the remaining component may be dissolved in the first solvent or a second solvent different from the first solvent, and the resulting solutions may be mixed. Alternatively, the block copolymer (X) and the plasticizer (Z) may be melt-kneaded in advance to prepare a mixture, to which the tackifier (Y) is added and dissolved in a solvent. In any of the above methods, other additives may be added at an appropriate timing. When dissolving each of the components in a solvent, there is no particular limitation as to which of the component to be dissolved and the solvent is added relative to the other; the component may be added to the solvent, or the solvent may be added to the component.

[0155] In the above step 1-2, examples of a method for extracting the polymer from the mixed solution include a method for solidifying the resin component (steam stripping) and a spray-drying method in which the polymer solution is heated to a high temperature and a high pressure and then sprayed under normal pressure to extract the resin component.

[0156]

[0044] The above-mentioned production method (II) (hereinafter also referred to as "production method (II)") has a step (step 2-1) of melt-kneading the block copolymer (X) and the tackifier (Y). The production method (II) has the advantages that it does not require a solvent and that it is easy to produce a wide variety of pressure-sensitive adhesive compositions in small lots using the same production equipment.

[0157] In the melt-kneading step (step 2-1), in the method for producing a pressure-sensitive adhesive composition, it is preferable to melt the block copolymer (X) and then add the tackifier (Y) and then perform melt-kneading, from the viewpoint of easily increasing the dispersibility of the tackifier (Y).

[0158] In the above step 2-1, from the viewpoint of easily increasing productivity, it is preferable to use a twin-screw extruder and add the tackifier (Y) to the molten block copolymer (X) midway through the extrusion path of the twin-screw extruder and perform melt kneading. When the above plasticizer (Z) is used, the plasticizer (Z) may be mixed in advance with at least one selected from the group consisting of the block copolymer (X) and the tackifier (Y), and the other component or other additives may be added to this mixture. In this case, a pressure-sensitive adhesive composition in which the plasticizer (Z) is diluted to a predetermined concentration can be prepared by preparing a mixture in which the plasticizer (Z) such as the liquid rubber component (Za) is contained at a relatively high concentration relative to the block copolymer (X), and then adding the tackifier (Y) to this mixture and melt kneading.

[0159] [Method of Using the Pressure-Sensitive Adhesive Composition] The pressure-sensitive adhesive composition according to this embodiment can be used in various methods, such as those described below. - Method of Use (i): The pressure-sensitive adhesive composition is used as a pressure-sensitive adhesive as is, and two adherends are pressure-bonded via a layer of the pressure-sensitive adhesive composition (pressure-sensitive adhesive layer). In this case, the pressure-sensitive adhesive composition may be applied to at least one of the two adherends, and then the two adherends may be pressed relative to each other via the pressure-sensitive adhesive layer, or the two adherends may be arranged with a small space between them, and the pressure-sensitive adhesive composition may be filled into the space. The pressure-sensitive adhesive layer may be formed by coating directly onto the adherend, or a pressure-sensitive adhesive layer formed by coating on a temporary support may be transferred onto the adherend. Note that, when forming a pressure-sensitive adhesive layer or filling a space with the pressure-sensitive adhesive composition, it is preferable to dissolve the pressure-sensitive adhesive composition in a solvent in advance to increase its fluidity. - Method of Use (ii): Heat to reduce the viscosity before use. When the pressure-sensitive adhesive composition has a high melt viscosity or when it is necessary to apply it without using a solvent, it is preferable to heat the pressure-sensitive adhesive composition to soften it to a predetermined viscosity before use. In this method of use, the pressure-sensitive adhesive composition can be heated and softened before being applied to at least one of two adherends, or the pressure-sensitive adhesive composition can be applied to at least one of two adherends and then heated to soften it, and the two adherends can be pressed relative to each other via the softened pressure-sensitive adhesive composition. Alternatively, the two adherends can be arranged with a small space between them, and the space can be filled with a heat-molten pressure-sensitive adhesive composition. - Method of use (iii): The pressure-sensitive adhesive composition is used after being irradiated with UV light to cause crosslinking. In this case, it is preferable to form a pressure-sensitive adhesive layer according to the procedure described in the above method of use (i) or (ii), and then crosslink the pressure-sensitive adhesive composition by irradiation with UV light before bonding the adherends together. When at least one of the adherends is UV-transparent, it is also possible to bond one adherend to the other via the pressure-sensitive adhesive layer, or to fill the space between the two adherends with the pressure-sensitive adhesive composition, and then irradiate the pressure-sensitive adhesive composition with UV light via the UV-transparent adherend to crosslink the pressure-sensitive adhesive composition. In this method of use, it is preferable to irradiate with UV light within a range that does not excessively reduce the adhesiveness of the adhesive layer.Usage method (iv): After adhesively bonding the adherends, if necessary, UV light is irradiated to peel the adherends. In a state in which two adherends are adhesively bonded by a pressure-sensitive adhesive layer formed by any of the above usage methods (i) to (iii), the pressure-sensitive adhesive layer is irradiated with UV light to promote crosslinking and reduce the adhesive properties of the pressure-sensitive adhesive layer. This allows the pressure-sensitive adhesive layer to be easily peeled off from the adherends. When the pressure-sensitive adhesive composition contains a crosslinking agent, from the viewpoint of avoiding surface curing inhibition due to oxygen inhibition, it is preferable, for example, to cover the pressure-sensitive adhesive composition with an oxygen-blocking film such as a polypropylene film, a polyethylene terephthalate film, or a Teflon (registered trademark) film to prevent the surface from coming into contact with oxygen, and then irradiate with UV light through the oxygen-blocking film, or to irradiate with UV light in an atmosphere in which oxygen has been replaced with an inert gas such as nitrogen gas or carbon dioxide gas.

[0160] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way. β-Farnesene (purity 97.6% by mass, manufactured by Amyris, Inc.) was purified using 3 Å molecular sieves and distilled under a nitrogen atmosphere to remove hydrocarbon impurities such as zingiberene, bisabolene, farnesene epoxide, farnesol isomers, E,E-farnesol, squalene, ergosterol, and several dimers of farnesene, before being used in the following polymerization. The materials used in the following examples and comparative examples are as follows:

[0161] <Block copolymers> - Unhydrogenated block copolymer (X-1) of Production Example 1 described below - Hydrogenated block copolymer (X-2) of Production Example 2 described below - Hydrogenated block copolymer (X-3) of Production Example 3 described below - Unhydrogenated block copolymer (X-4) of Production Example 4 described below - Unhydrogenated block copolymer (X-5) of Production Example 5 described below - Styrene-isoprene-styrene block copolymer Product name: Quintac 3421, manufactured by Zeon Corporation <Tackifiers (Y)> - Product name: Arcon P90, hydrogenated petroleum resin manufactured by Arakawa Chemical Industries, Ltd., softening point 90±5°C - Product name: Arcon P125, hydrogenated petroleum resin manufactured by Arakawa Chemical Industries, Ltd., softening point 125±5°C - Product name: Arcon M135, partially hydrogenated petroleum resin manufactured by Arakawa Chemical Industries, Ltd., softening point 135±5°C - Product name: YS RESIN TO105, Yasuhara Chemical Co., Ltd., aromatic modified terpene resin, softening point 105±5°C. Product name: T-REZ HA085, ENEOS Corporation, hydrogenated petroleum resin (DCPD), softening point 85°C±5°C. Product name: T-REZ RB100, ENEOS Corporation, aliphatic hydrocarbon resin (C5), softening point 100°C±5°C. Product name: YS POLYSTER TH130, Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 130±5°C. Product name: CLEARON P150, Yasuhara Chemical Co., Ltd., hydrogenated terpene resin, softening point 152°C±5°C. Product name: CLEARON M115, Yasuhara Chemical Co., Ltd., aromatic modified hydrogenated terpene resin, softening point 115°C±5°C. <Liquid rubber component (Za)> Unhydrogenated liquid rubber (Z-1) of Production Example 6 described below Unhydrogenated liquid rubber (Z-2) of Production Example 7 described below <Biomass-derived plasticizer (Zb)> Product name VIVA-B-FIX 10227, natural product-derived oil manufactured by H&R <Synthetic plasticizer (Zc)> Product name PW-90, paraffinic process oil manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity (40°C): 90 mm ２ / s <Antioxidant> Product name: Adekastab AO-60, manufactured by ADEKA Corporation. Melting point: 110-130°C, molecular weight: 1,178 <Photoradical polymerization initiator> Product name: Irgacure 651, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 2,2-dimethoxy-2-phenylacetophenone <Crosslinking agent> Tris(mercaptoacetic acid)trimethylolpropane, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. 1,6-bis(acryloyloxy)hexane, manufactured by Tokyo Chemical Industry Co., Ltd.

[0162] [Measurement Methods] Details of the methods for measuring the physical properties of the polymers obtained in the following Production Examples are as follows. (1) Measurement of Weight Average Molecular Weight and Molecular Weight Distribution The following items were measured by GPC (gel permeation chromatography). Specifically, the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of each component were determined by GPC in terms of standard polystyrene equivalent molecular weight. - Weight average molecular weight of polymer block (A) - Weight average molecular weight of polymer block (B) - Weight average molecular weight of unhydrogenated block polymer - Molecular weight distribution of unhydrogenated block polymer - Weight average molecular weight of hydrogenated block polymer - Molecular weight distribution of hydrogenated block polymer - Weight average molecular weight of unhydrogenated liquid rubber - Molecular weight distribution of unhydrogenated liquid rubber The measuring equipment and conditions were as follows. Apparatus: GPC apparatus "HLC-8320GPC" manufactured by Tosoh Corporation Separation column: Column "TSKgel Super HZ4000" manufactured by Tosoh Corporation Eluent: tetrahydrofuran Eluent flow rate: 0.7 mL / min Sample concentration: 5 mg / 10 mL Column temperature: 40°C The weight average molecular weight of each polymer block in the block copolymer was determined by measuring a sampled liquid each time the polymerization of each polymer block was completed in the production process.

[0163] (2) Method for measuring hydrogenation rate: The unhydrogenated block copolymer and the hydrogenated block copolymer were each dissolved in a deuterated chloroform solvent (CDCl ３ ) and heated at 50°C using a Lambda-500 (manufactured by JEOL Ltd.). １H-NMR was measured. The hydrogenation rate of the hydrogenated block copolymer was calculated from the peak attributable to styrene appearing at 6.5 to 7.5 ppm and the peak of the protons of the carbon-carbon double bond appearing at 4.5 to 6.0 ppm in the obtained spectrum (peak attributable to the carbon-carbon double bond) using the following formula: Hydrogenation rate (mol %) = {1 - (ratio of the peak area attributable to the carbon-carbon double bond to the peak area attributable to styrene in the hydrogenated block copolymer) / (ratio of the peak area attributable to the carbon-carbon double bond to the peak area attributable to styrene in the unhydrogenated block copolymer)} × 100

[0164] (3) Vinyl bond content The block copolymer before hydrogenation was dissolved in a deuterated chloroform solvent (CDCl ３ ) and dissolved in １ H-NMR measurement was carried out [apparatus: "ADVANCE 400 Nano bay" (manufactured by Bruker), measurement temperature: 30°C]. The vinyl bond amount of polymer block (B) was calculated from the ratio of the peak area corresponding to the 3,13-bond unit and the 1,2-bond unit in β-farnesene to the total peak area of ​​the structural units derived from β-farnesene. Furthermore, for liquid rubber component (Z-1) described below, the vinyl bond amount was calculated in the same manner as above, and for liquid rubber component (Z-2), the vinyl bond amount was calculated from the ratio of the peak area corresponding to the 1,2-bond unit of butadiene to the total peak area of ​​the structural units derived from butadiene, in the same manner as above.

[0165] (4) Melt Viscosity of Liquid Rubber Component (Za) at 38°C The melt viscosity of the liquid rubber component (Za) at 38°C was measured using a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.).

[0166] (5) Glass Transition Temperature (Tg) A disk-shaped test piece having a diameter of 8 mm and a thickness of 1 mm was cut out from the adhesive layer (Y) produced using a compression press molding machine. Dynamic viscoelasticity measurement was performed on this test piece using an ARES-G2 rheometer (manufactured by TA Instruments) under the following conditions: -100°C to +50°C, a frequency of 1 Hz, and a strain of 0.1%, and the loss tangent (tan δ) was measured at this time, and the peak top temperature was taken as Tg. (Dynamic viscoelasticity measurement device and measurement conditions) Parallel plates: diameter 8 mm Vibration mode: torsional vibration Strain amount: 0.1% Frequency: 1 Hz Measurement temperature: -100 to +50°C Heating rate: 3°C / min

[0167] Production Example 1 Production of Unhydrogenated Block Copolymer (X-1) A nitrogen-purged, dried pressure vessel was charged with 62.4 kg of cyclohexane as a solvent and 0.0535 kg of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and the temperature was raised to 50°C. After that, 1.40 kg of styrene (1) was added and polymerization was carried out for 1 hour, followed by the addition of 12.79 kg of β-farnesene and polymerization for 2 hours, and further the addition of 1.40 kg of styrene (2) and polymerization for 1 hour to obtain a polystyrene-poly(β-farnesene)-polystyrene triblock copolymer (hereinafter also referred to as "unhydrogenated block copolymer (X-1)").

[0168] [Production Example 2] Production of hydrogenated block copolymer (X-2) A nitrogen-purged, dried pressure vessel was charged with 62.4 kg of cyclohexane as a solvent and 0.0535 kg of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and the temperature was raised to 50 ° C. After that, 1.40 kg of styrene (1) was added and polymerization was carried out for 1 hour, followed by 12.79 kg of β-farnesene and polymerization for 2 hours, and then 1.40 kg of styrene (2) was added and polymerization was carried out for 1 hour, to obtain a reaction solution containing a polystyrene-poly(β-farnesene)-polystyrene triblock copolymer. Palladium carbon (palladium loading: 5 mass%) was added as a hydrogenation catalyst to this reaction solution in an amount of 2.5 mass% relative to the triblock copolymer, and the reaction was carried out for 10 hours under conditions of a hydrogen pressure of 2 MPa and 150 ° C. After allowing to cool and releasing the pressure, the palladium carbon was removed by filtration, and the filtrate was concentrated and further dried in vacuo to obtain a hydrogenated product of polystyrene-poly(β-farnesene)-polystyrene triblock copolymer (hereinafter also referred to as "hydrogenated block copolymer (X-2)").

[0169] Production Example 3 Production of Hydrogenated Block Copolymer (X-3) A hydrogenated product of polystyrene-poly(β-farnesene)-polystyrene triblock copolymer (hereinafter also referred to as "hydrogenated block copolymer (X-3)") was obtained in the same manner as in Production Example 2, except that palladium on carbon (palladium loading: 5% by mass) was used as the hydrogenation catalyst in an amount of 5% by mass relative to the triblock copolymer.

[0170] Production Example 4 Production of Unhydrogenated Block Copolymer (X-4) A pressure-resistant vessel that had been purged with nitrogen and dried was charged with 62.4 kg of cyclohexane as a solvent and 0.0535 kg of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and the temperature was raised to 50°C. After that, 1.40 kg of styrene (1) was added and polymerization was carried out for 1 hour, and subsequently 6.40 kg of β-farnesene was added and polymerization was carried out for 2 hours to obtain a polystyrene-poly(β-farnesene) diblock copolymer (hereinafter also referred to as "unhydrogenated block copolymer (X-4)").

[0171] Production Example 5 Production of Unhydrogenated Block Copolymer (X-5) A nitrogen-purged, dried pressure vessel was charged with 62.4 kg of cyclohexane as a solvent and 0.0460 kg of sec-butyllithium (10.5 mass% cyclohexane solution) as an anionic polymerization initiator, and the temperature was raised to 50°C. After that, 2.34 kg of styrene (1) was added and polymerization was carried out for 1 hour, subsequently 10.92 kg of β-farnesene was added and polymerization was carried out for 2 hours, and further 2.34 kg of styrene (2) was added and polymerization was carried out for 1 hour, thereby obtaining a polystyrene-poly(β-farnesene)-polystyrene triblock copolymer (hereinafter also referred to as "unhydrogenated block copolymer (X-5)").

[0172] Various physical properties were measured according to the above-mentioned measurement procedures for each of the block copolymers obtained in Production Examples 1 to 5. The measurement results are shown in Table 1 together with their compositions.

[0173]

[0174] The details of notes *1 to *4 in Table 1 are as follows: *1: Indicates the content [mass %] of structural units derived from β-farnesene in polymer block (B). *2: Indicates the mass ratio between the content of polymer block (A) and the total content of polymer block (A) and polymer block (B). *3: "St-F-St" indicates a polystyrene-poly(β-farnesene)-polystyrene triblock copolymer. "St-F" indicates a polystyrene-poly(β-farnesene) diblock copolymer. *4: Indicates the hydrogenation rate of carbon-carbon double bonds relative to the conjugated diene compound units in the unhydrogenated block copolymer, which is the block copolymer before hydrogenation; specifically, indicates the value measured by the method described in the Examples.

[0175] As shown in Table 1, the unhydrogenated block copolymer (X-1) of Production Example 1, the hydrogenated block copolymer (X-2) of Production Example 2, the hydrogenated block copolymer (X-3) of Production Example 3, the unhydrogenated block copolymer (X-4) of Production Example 4, and the unhydrogenated block copolymer (X-5) of Production Example 5 all have structural units derived from β-farnesene. Note that, since the polymer block (B) in each case contains only structural units derived from β-farnesene, the vinyl bond content of the polymer block (B-1) is also the vinyl bond content of the polymer block (B). The unhydrogenated block copolymer (X-1), the hydrogenated block copolymer (X-2), the hydrogenated block copolymer (X-3), and the unhydrogenated block copolymer (X-5) each have a polystyrene-poly(β-farnesene)-polystyrene triblock skeleton. The unhydrogenated block copolymer (X-4) has a polystyrene-poly(β-farnesene) diblock skeleton and has a weight-average molecular weight smaller than those of the above-mentioned (X-1), (X-2), (X-3), and (X-5). The unhydrogenated block copolymers (X-1), (X-4), and (X-5) are not hydrogenated, and the hydrogenated block copolymer (X-2) has a hydrogenation rate of less than 50 mol%. On the other hand, the hydrogenated block copolymer (X-3) has a hydrogenation rate of 50 mol% or more.

[0176] Production Example 6 Production of Unhydrogenated Liquid Rubber (Z-1) A pressure-resistant vessel that had been purged with nitrogen and dried was charged with 20.2 kg of cyclohexane as a solvent and 3.70 kg of s-butyllithium as a polymerization initiator, and the vessel was heated to 50°C. After that, 40.2 kg of β-farnesene was added and polymerization was carried out for 2 hours to obtain poly-β-farnesene rubber (hereinafter also referred to as "unhydrogenated liquid rubber (Z-1)").

[0177] [Production Example 7] Production of Unhydrogenated Liquid Rubber (Z-2) A nitrogen-purged, dried pressure vessel was charged with 23.0 kg of hexane as a solvent and 3.08 kg of n-butyllithium as a polymerization initiator, and the vessel was heated to 50°C. After that, 0.2 kg of N,N,N',N'-tetramethylethylenediamine and 25.0 kg of butadiene were added and polymerization was carried out for 2 hours to obtain polybutadiene rubber (hereinafter also referred to as "unhydrogenated liquid rubber (Z-2)").

[0178] The unhydrogenated liquid rubbers obtained in Production Examples 6 and 7 were subjected to measurements of various physical properties according to the above-mentioned procedures. The measurement results are shown in Table 2 together with their compositions. In addition, among the annotations *5 in Table 2, "Far" represents poly-β-farnesene and "Bd" represents polybutadiene.

[0179]

[0180] As is clear from Table 2, the unhydrogenated liquid rubber (Z-1) of Production Example 6 has a polyfarnesene structure and a high biobased content. Furthermore, since it has a small vinyl bond content and a low melt viscosity at 38°C, it is easy to uniformly disperse it in the pressure-sensitive adhesive composition of the present invention and also to improve its coatability. On the other hand, the unhydrogenated liquid rubber (Z-2) of Production Example 7 has a polybutadiene structure and does not contain any naturally occurring components, so it is difficult to increase the biobased content of the pressure-sensitive adhesive composition. On the other hand, since it has a higher vinyl bond content than the unhydrogenated liquid rubber (Z-1), it is easy to increase the crosslinkability by irradiation with energy rays such as ultraviolet rays. Therefore, it is clear that it is possible to achieve a good balance between the pressure-sensitive adhesive properties and heat resistance of the pressure-sensitive adhesive composition.

[0181] Next, examples of the adhesive composition will be described.

[0182] [Evaluation Methods] Details of the methods for measuring the physical properties and the evaluation methods for the evaluation items of the pressure-sensitive adhesive compositions obtained in the following Examples and Comparative Examples are as follows.

[0183] (6) Bio-based Content The bio-based content of each component used to prepare the pressure-sensitive adhesive composition and each pressure-sensitive adhesive composition was measured in accordance with ASTM D6866-21. Specifically, each of the components was combusted, and the CO ２ The CO ２ Using an accelerator mass spectrometer (AMS), １４ The concentration of CO in the atmosphere was measured. ２ in １４ The concentration of C and the measured １４The biobased content was calculated by comparing the concentration of C with that of the block copolymer (X), tackifier (Y), and plasticizer (Z) used in the above Examples and Comparative Examples, and based on the biobased content of each component, using the following formula: Biobased content of adhesive composition (mass%) = (X1 × X2 / 100) + (Y1 × Y2 / 100) + (Z1 × Z2 / 100) In the above formula, X1 represents the mass ratio (mass%) of the block copolymer (X) relative to the total mass of the adhesive composition, Y1 represents the mass ratio (mass%) of the tackifier (Y) relative to the total mass of the adhesive composition, and Z1 represents the mass ratio (mass%) of the plasticizer (Z) relative to the total mass of the adhesive composition. X2 (mass%) represents the biobased content of the block copolymer (X), Y2 (mass%) represents the biobased content of the tackifier (Y), and Z2 (mass%) represents the biobased content of the plasticizer (Z).

[0184] (7) Coating Thickness The coating thickness of the pressure-sensitive adhesive composition prepared in the Examples and Comparative Examples was measured using a digital thickness meter (product name SMD-565J-L, manufactured by TECLOK CORPORATION).

[0185]

[0044] (8) Peel test The PET films on which a coating film of the pressure-sensitive adhesive composition produced in the Examples and Comparative Examples had been formed were cut to a width of 25 mm, and attached to a smooth stainless steel plate (product name SUS304, thickness 1 mm, manufactured by ACC Co.) so that the coating film was in contact with the stainless steel plate, and then pressed using a 2 kg rubber roller at a speed of 10 mm / min, and then allowed to stand for 24 hours in an atmosphere of 23±1°C and humidity of 50±5%. Thereafter, a 180° peel test was carried out in accordance with JIS Z 0237:2009 at a temperature of 23°C and a peel speed of 200 mm / min, and the 180° peel strength was measured.

[0186] (9) Ball Tack The PET films on which coating films of the pressure-sensitive adhesive compositions were formed, which were produced in the Examples and Comparative Examples, were measured for ball tack property values ​​in accordance with JIS Z0237:2009.

[0187] (10) Shear Interfacial Fracture Temperature (SAFT) For the PET films on which a coating film of the pressure-sensitive adhesive composition was formed, produced in the Examples and Comparative Examples, the weight drop time was measured in accordance with ASTM D3654M:2019 under the conditions of an adhesive area of ​​25 mm × 25 mm, a weight of 500 g, a temperature range of 40 to 205°C, and a temperature rise rate of 0.5°C / min, and this was taken as SAFT.

[0188] (11) Haze The haze of the PET films on which the coating films of the pressure-sensitive adhesive compositions were formed, which were produced in the examples and comparative examples, was measured in accordance with JIS K 7136:2000.

[0189] (12) Melt Viscosity at 180°C The melt viscosity at 180°C of the pressure-sensitive adhesive compositions prepared in the Examples and Comparative Examples was measured using a Brookfield viscometer (manufactured by BROOKFIELD ENGINEERING LABS. INC.).

[0190] Examples A1 to A9 and Comparative Examples CA1 to CA5 A solution was prepared by dissolving each component in the amounts shown in Table 3 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solid content concentration (TS) to 25 mass%, thereby preparing a pressure-sensitive adhesive composition for coating diluted to a ratio of 20 parts by mass per 60 parts by mass of cyclohexane. In this specification, the TS of a pressure-sensitive adhesive composition diluted with a solvent refers to the concentration of the solids (total of the block copolymer, tackifier, and plasticizer) in the pressure-sensitive adhesive composition diluted with the solvent. This pressure-sensitive adhesive composition for coating was applied to a polyethylene terephthalate (PET) film at a speed of 50 mm / sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then heated and dried at 60°C for 30 minutes to form a coating film of the pressure-sensitive adhesive composition with a thickness of 20 μm.

[0191] The coating films of the pressure-sensitive adhesive compositions of Examples A1 to A9 and Comparative Examples CA1 to CA5 thus prepared were subjected to measurements of various physical properties according to the measurement procedures described above. The measurement results are shown in Table 3 together with the compositions.

[0192]

[0193] As shown in Table 3, the pressure-sensitive adhesive compositions of Examples A1 to A9 have a high bio-based content, a high 180° peel strength, and good pressure-sensitive adhesive properties. Furthermore, the SAFT values ​​are 100°C or higher, which indicates that they have high heat resistance.

[0194] In contrast, the pressure-sensitive adhesive compositions of Comparative Examples CA1 to CA5, which do not contain either an "unhydrogenated block copolymer" or a "hydrogenated block copolymer having a hydrogenation rate of less than 50 mol%," all had 180° peel strengths lower than the values ​​in the above Examples, indicating that they have inferior pressure-sensitive adhesive properties compared to the pressure-sensitive adhesive compositions of the above Examples. Furthermore, the pressure-sensitive adhesive compositions of Comparative Examples CA2 and CA3 had smaller SAFT and 180° peel strength values, indicating that they have inferior heat resistance and pressure-sensitive adhesive properties compared to the pressure-sensitive adhesive composition of Example A3, which has the same composition except for using a "hydrogenated block copolymer having a hydrogenation rate of 50 mol% or more" or a "unhydrogenated block copolymer not containing a structural unit derived from farnesene" as the block copolymer. Furthermore, the pressure-sensitive adhesive composition of Comparative Example CA5 had smaller SAFT and 180° peel strength values, indicating that they have inferior heat resistance and pressure-sensitive adhesive properties compared to the pressure-sensitive adhesive composition of Example A1, which has the same composition except for using a "unhydrogenated block copolymer not containing a structural unit derived from farnesene" as the block copolymer.

[0063] Furthermore, the adhesive composition of Comparative Example CA1 has a smaller 180° peel strength value and is therefore inferior in adhesive properties compared to the adhesive compositions of Examples A1 and A5, which have the same composition except for using a "hydrogenated block copolymer having a hydrogenation rate of 50 mol% or more" as the block copolymer. Furthermore, the adhesive composition of Comparative Example CA4 has a smaller 180° peel strength value and is therefore inferior in adhesive properties compared to the adhesive composition of Example A8, which has the same composition except for using a "hydrogenated block copolymer having a hydrogenation rate of 50 mol% or more" as the block copolymer.

[0195] [Examples B1 to B9, Comparative Examples CB1 to CB2] A solution was prepared by dissolving each component in the amount shown in Table 4 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solids concentration (TS) to 25 mass%, thereby preparing a pressure-sensitive adhesive composition for coating diluted to a ratio of 20 parts by mass to 60 parts by mass of cyclohexane. This pressure-sensitive adhesive composition for coating was applied to a polyethylene terephthalate (PET) film at a speed of 50 mm / sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then heated and dried at 60°C for 30 minutes to form a coating film of the pressure-sensitive adhesive composition having a thickness of 20 μm.

[0196] Next, the coating film was irradiated with a UV dose of 300 mJ / cm under an oxygen atmosphere using an F300S&LC-6B UV conveyor system (manufactured by Heraeus). ２ , 500 mJ / cm ２ or 1,000 mJ / cm ２ The adhesive composition was then irradiated with UV light (wavelength 365 nm) to crosslink the adhesive composition.

[0197] The crosslinked coating films of the pressure-sensitive adhesive compositions of Examples B1 to B9 and Comparative Examples CB1 and CB2 thus prepared were subjected to measurements of various physical properties according to the above-mentioned measurement procedures. The measurement results are shown in Table 4 together with their compositions.

[0198]

[0199] As shown in Table 4, the pressure-sensitive adhesive compositions of Examples B1 to B9 have a high biobased content and are crosslinked, and therefore have a significantly increased SAFT value and high heat resistance compared to the pressure-sensitive adhesive compositions of Examples A1 to A9. In addition, the pressure-sensitive adhesive compositions of Examples B2 to B4 and those with UV light exposure doses of 300 and 500 mJ / cm ２ In Example B1, when the UV light irradiation dose was 1,000 mJ / cm, the 180° peel strength of the adhesive composition was high, and it was found that the adhesive composition had good adhesive properties. ２In Example B1, when the UV light irradiation dose was 300 mJ / cm, the 180° peel strength of the pressure-sensitive adhesive composition was low, but it was found to have a predetermined value of 2.5 N / 25 mm or more. ２ The SAFT value when the UV light irradiation dose was 500 and 1,000 mJ / cm ２ However, it is higher than the SAFT values ​​of the pressure-sensitive adhesive compositions of Examples A1 to A9 described above, and it can be seen that crosslinking can proceed to some extent even with a small amount of UV light irradiation.

[0200] In contrast, the pressure-sensitive adhesive composition of Comparative Example CB1 had a viscosity of 300 and 500 mJ / cm compared to the pressure-sensitive adhesive composition of Example B1, which had the same composition except that a "hydrogenated block copolymer having a hydrogenation rate of 50 mol% or more" was used as the block copolymer. ２ In other words, it can be understood that crosslinking is difficult to proceed when the UV irradiation dose is smaller than that of Example B1. ２ Similarly, the pressure-sensitive adhesive composition of Comparative Example CB2 also had a low SAFT value of 1,000 mJ / cm compared to the pressure-sensitive adhesive composition of Example B1, which had the same composition except for using an "unhydrogenated block copolymer not containing a structural unit derived from farnesene" as the block copolymer. ２ It can be seen that the SAFT value and 180° peel strength value after UV irradiation at 1000 kJ / cm2 were small, and the heat resistance and adhesiveness were poor.

[0201] [Examples C1 to C5 and Comparative Examples CC1 to CC5] A solution was prepared by dissolving each component in the amount shown in Table 5 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solids concentration (TS) to 25 mass%, thereby preparing a pressure-sensitive adhesive composition diluted to a ratio of 20 parts by mass to 60 parts by mass of cyclohexane. 10 g of this pressure-sensitive adhesive composition was poured into a box with release paper measuring W 5 cm × D 5 cm × H 2 cm, air-dried at room temperature for 48 hours, and then further dried at 60°C for 2 hours, thereby preparing a sheet with a thickness of 1 mm.

[0202] For the sheets of the pressure-sensitive adhesive compositions of Examples C1 to C5 and Comparative Examples CC1 to CC5 thus prepared, various physical properties were measured according to the measurement procedures described above. The measurement results are shown in Table 5 together with their compositions.

[0203]

[0204] As shown in Table 5, the adhesive compositions of Examples C1 to C5 have relatively small haze values, and it can be seen that the compatibility between the block copolymer and the tackifier is high.

[0205] In contrast, the pressure-sensitive adhesive compositions of Comparative Examples CC1 to CC5 have larger haze values ​​than the pressure-sensitive adhesive compositions of Examples C1 to C5, which have the same composition except that a "hydrogenated block copolymer having a hydrogenation rate of 50 mol % or more" was used as the block copolymer, and it is clear that the compatibility between the block copolymer and the tackifier is low.

[0206] [Examples D1 to D5 and Comparative Examples CD1 to CD2] Solutions were prepared by dissolving each component in the amounts shown in Table 6 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solids concentration (TS) to 25 mass%, thereby preparing a diluted composition with a ratio of 20 parts by mass to 60 parts by mass of cyclohexane. This composition was then air-dried at room temperature for 48 hours and then further dried at 60°C for 2 hours, thereby preparing a pressure-sensitive adhesive composition. The pressure-sensitive adhesive compositions of Examples D1 to D5 and Comparative Examples CD1 to CD2 prepared in this manner were measured for biobased content and melt viscosity at 180°C using the procedures described above. The measurement results, along with their compositions, are shown in Table 6.

[0207]

[0208]

[0111] As shown in Table 6, the pressure-sensitive adhesive compositions of Examples D1 to D5 had a high bio-based degree, a low melt viscosity at 180°C, and good fluidity when heated to 180°C, and it can be seen that they are suitable as hot-melt pressure-sensitive adhesive compositions.

[0209] In contrast, the adhesive compositions of Comparative Examples CD1 and CD2 have higher melt viscosities at 180°C than those of the Examples, and are found to have inferior fluidity when heated to 180°C to the adhesive compositions of the Examples.

[0210] The pressure-sensitive adhesive compositions of Examples D1 to D5 and Comparative Examples CD1 and CD2 were prepared using a solvent, but each pressure-sensitive adhesive composition may also be prepared by melt-kneading each component in the amount shown in Table 6. In this case, the same measurement results as those described above are obtained.

[0211] [Examples E1 to E6 and Comparative Examples CE1 to CE3] A solution was prepared by dissolving each component in the amount shown in Table 7 in cyclohexane. Next, cyclohexane was further added to the above solution to adjust the solids concentration (TS) to 25 mass%, thereby preparing a pressure-sensitive adhesive composition for coating diluted to a ratio of 20 parts by mass to 60 parts by mass of cyclohexane. This pressure-sensitive adhesive composition for coating was applied to a polyethylene terephthalate (PET) film at a speed of 50 mm / sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then heated and dried at 60°C for 30 minutes to form a coating film of the pressure-sensitive adhesive composition having a thickness of 20 μm.

[0212] Next, the coating film was irradiated with a UV dose of 300 mJ / cm under an oxygen atmosphere using an F300S&LC-6B UV conveyor system (manufactured by Heraeus). ２ , or 1,000 mJ / cm ２ The adhesive composition was then irradiated with UV light (wavelength 365 nm) to crosslink the adhesive composition.

[0213] The crosslinked coating films of the pressure-sensitive adhesive compositions of Examples E1 to E6 and Comparative Examples CE1 to CE3 thus prepared were subjected to measurements of various physical properties according to the above-mentioned measurement procedures. The measurement results are shown in Table 7 together with their compositions.

[0214]

[0215] As shown in Table 7, the pressure-sensitive adhesive compositions of Examples E1 to E6 were exposed to an irradiation dose of 300 mJ / cm ２It can be seen that the SAFT value is slightly lower when the UV irradiation dose is 1000 or more, and this tendency is slightly stronger when the crosslinking agent content is low. However, high SAFT values ​​are shown for all UV irradiation doses and crosslinking agent contents, and it can be seen that crosslinking can proceed appropriately with a small UV irradiation dose.

[0216] In contrast, the pressure-sensitive adhesive compositions of Comparative Examples CE1 to CE3 were irradiated with UV light at a dose of 300 mJ / cm ２ In this case, the UV irradiation dose is 1,000 mJ / cm ２ It can be seen that the SAFT values ​​are lower than in the case of Comparative Examples CE1 to CE3, and this tendency becomes more pronounced when the content of crosslinking agent is low. Specifically, compared to Examples E1 to E3 or E4 to E6, which have the same content of crosslinking agent as Comparative Examples CE1 to CE3, the pressure-sensitive adhesive compositions of Comparative Examples CE1 to CE3 have lower SAFT values ​​at the same irradiation dose, and also have lower SAFT values ​​at an irradiation dose of 1,000 mJ / cm. ２ The SAFT value at this time is 300 mJ / cm ２ As is clear from the comparison between Comparative Example CE2 and Example E2 or Example E5, when the content of the crosslinking agent is reduced, the degree of decrease in the SAFT value is large when the irradiation dose is 1,000 mJ / cm ２ The SAFT value at this time is 300 mJ / cm ２ In other words, it can be seen that in order to achieve a high SAFT, i.e., high heat resistance, the pressure-sensitive adhesive compositions of Comparative Examples CE1 to CE3 require a larger UV irradiation dose than the pressure-sensitive adhesive compositions of Examples E1 to E3 or E4 to E6, which have the same content of crosslinking agent as Comparative Examples CE1 to CE3, respectively.

[0217] [Example F1 and Comparative Example CF1] A pressure-sensitive adhesive composition was prepared in the same procedure as in Example B1, except that in the above-mentioned Example B1, 1,6-bis(acryloyloxy)hexane was used as the crosslinking agent instead of tris(mercaptoacetic acid)trimethylolpropane in the same amount by mass (Example F1). Further, in the above-mentioned Comparative Example CB1, a pressure-sensitive adhesive composition was prepared in the same procedure as in Comparative Example CB1, except that in the above-mentioned Comparative Example CB1, 1,6-bis(acryloyloxy)hexane was used as the crosslinking agent instead of tris(mercaptoacetic acid)trimethylolpropane in the same amount by mass (Comparative Example CF1).

[0218] This pressure-sensitive adhesive composition for coating was applied onto a polyethylene terephthalate (PET) film at a speed of 50 mm / sec using an automatic coater (PI-1020 AUTO FILM APPLICATOR, manufactured by Tester Sangyo Co., Ltd.), and then the film was dried by heating at 60°C for 30 minutes, thereby forming a coating film of the pressure-sensitive adhesive composition having a thickness of 20 µm.

[0219] Next, a plurality of test pieces were prepared by attaching an oxygen barrier film (a PET film manufactured by Toyobo Co., Ltd., thickness 50 μm) to the coating film. A plurality of test pieces to which the oxygen barrier film was not attached were also prepared. These test pieces were then irradiated with UV light (wavelength 365 nm) using an F300S&LC-6B UV conveyor system (manufactured by Heraeus) at the irradiation doses shown in Table 8 below, thereby crosslinking the pressure-sensitive adhesive composition. The test pieces to which the oxygen barrier film was attached were irradiated with UV light via the oxygen barrier film, and the adhesive composition was irradiated directly with UV light for the test pieces to which the oxygen barrier film was not attached.

[0220] The crosslinked coating films of the pressure-sensitive adhesive compositions of Example F1 and Comparative Example CF1 thus prepared were subjected to measurements of various physical properties according to the above-mentioned measurement procedures. The measurement results are shown in Table 8 together with their compositions.

[0221]

[0222] As shown in Table 8, the coating film crosslinked from the pressure-sensitive adhesive composition of Example F1 had a high SAFT value, indicating that a pressure-sensitive adhesive layer with high heat resistance could be obtained even when using the acrylic crosslinking agent 1,6-bis(acryloyloxy)hexane. In particular, it was found that when crosslinking was performed by irradiating UV light with an oxygen barrier film attached, the SAFT value increased even with a smaller irradiation dose compared to when UV light was irradiated without an oxygen barrier film (i.e., in the presence of oxygen). Furthermore, without UV light irradiation, the 180° peel strength of the pressure-sensitive adhesive composition of Example F1 was equivalent to the 180° peel strength (19 N / 25 mm) of the pressure-sensitive adhesive composition of Example A1 shown in Table 3. However, when an oxygen barrier film was attached and UV light was irradiated, the 180° peel strength was found to be significantly smaller, as shown in Table 8. Therefore, it can be seen that the pressure-sensitive adhesive composition can be easily peeled from an adherend by reducing its adhesive properties by light irradiation when necessary, and is therefore highly suitable for applications such as dicing tape. On the other hand, the coating film obtained by crosslinking the pressure-sensitive adhesive composition of Comparative Example CF1, which used the hydrogenated block copolymer (X-3), which is a hydrogenated block copolymer having a hydrogenation rate of 50% or more, had a smaller SAFT value than Example F1, indicating that the coating film was inferior in heat resistance.

[0223] The adhesive composition of the present invention has a high biobased content and provides suitable adhesive properties and high heat resistance. Therefore, it can be used by forming a coating to partially or completely cover a variety of articles, such as paper products, packaging materials, laminated wood panels, kitchen countertops, vehicles, labels, disposable diapers, hospital pads, feminine sanitary napkins, surgical drapes, tapes, cases, cartons, trays, medical devices, or bandages. It can also be used to bond any combination of a pair of adherends (including a combination of adherends made of the same material) selected from the group consisting of metal, wood, paper, plastic, rubber, glass, stone, granite, marble, masonry, porcelain, ceramics, tile, pottery, concrete, clay, sand, chalk, textiles, fabrics, nonwoven fabrics, leather, and composites thereof; sheets, strips, tapes, labels, tags, webs, discs, plates, films, and any molded articles. Furthermore, the adhesive composition of the present invention can be used as an adhesive layer of a dicing tape for temporarily fixing workpieces, such as semiconductor wafers and semiconductor devices.

[0033] The adhesive composition of the present invention can also be used as a hot-melt adhesive composition, which is reduced in viscosity by heating and adhesively bonds to the various adherends described above.

Claims

1. A block copolymer (X) including a polymer block (A) containing a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing a structural unit derived from a conjugated diene compound, and a tackifier (Y), The block copolymer (X) contains, as the polymer block (B), at least one polymer block (B-1) containing a structural unit derived from β-farnesene, The pressure-sensitive adhesive composition, wherein the block copolymer (X) comprises at least one selected from the group consisting of an unhydrogenated block copolymer (X0) which is a block copolymer that has not been hydrogenated, and a hydrogenated block copolymer (X1) which is a block copolymer that has been hydrogenated and has a hydrogenation rate of less than 50 mol%.

2. The pressure-sensitive adhesive composition according to claim 1, wherein the content of the tackifier (Y) is 50 to 170 parts by mass based on 100 parts by mass of the block copolymer (X).

3. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the block copolymer (X) does not contain a diblock material composed of the polymer block (A) and the polymer block (B), or the content of the diblock material in the block copolymer (X) is more than 0 mass% and less than 60 mass%.

4. 2. The pressure-sensitive adhesive composition according to claim 1, wherein at least one selected from the group consisting of the unhydrogenated block copolymer (X0) and the hydrogenated block copolymer (X1) having a hydrogenation rate of less than 50 mol% is crosslinked.

5. The pressure-sensitive adhesive composition according to claim 1, wherein the block copolymer (X) has a glass transition temperature (Tg) of -52°C or lower.

6. The pressure-sensitive adhesive composition according to claim 1, further comprising at least one selected from the group consisting of a liquid rubber component (Za), a biomass-derived plasticizer (Zb), and a synthetic plasticizer (Zc).

7. 2. The pressure-sensitive adhesive composition according to claim 1, further comprising a liquid rubber component (Za), the liquid rubber component (Za) comprising at least one selected from the group consisting of an unhydrogenated liquid rubber (Za0) which is a non-hydrogenated liquid rubber, and a hydrogenated liquid rubber (Za1) which is a hydrogenated liquid rubber and has a hydrogenation rate of 90 mol% or less.

8. The pressure-sensitive adhesive composition according to claim 1, having a 180° peel strength of 10.0 N / 25 mm or more, measured in accordance with JIS Z 0237:2009 at a temperature of 23°C and a peel speed of 200 mm / min.

9. The pressure-sensitive adhesive composition according to claim 1, wherein the adhesive composition has a shear interface fracture temperature (SAFT) of 200°C or higher, calculated from the weight drop time under the conditions of an adhesive area of ​​25 mm x 25 mm, a weight of 500 g, a temperature range of 40 to 205°C, and a heating rate of 0.5°C / min in accordance with ASTM D3654M:2019.

10. The adhesive composition according to claim 1, wherein the adhesive composition has a bio-based degree of 10 to 100 mass % as measured in accordance with ASTM D6866-21.

11. The pressure-sensitive adhesive composition according to claim 1, wherein the vinyl bond amount in the polymer block (B-1) is 3 to 20 mol %.

12. The pressure-sensitive adhesive composition according to claim 1 , wherein the content of the polymer block (A) in the block copolymer (X) is 40 mass % or less.

13. A method for producing the pressure-sensitive adhesive composition according to any one of claims 1 to 12, comprising the steps of: (I) a step of dissolving the block copolymer (X) and the tackifier (Y) in a solvent and then distilling off the solvent, or (II) A method for producing a pressure-sensitive adhesive composition, comprising a step of melt-kneading a block copolymer (X) and a tackifier (Y).