Hot-melt adhesive composition

Abstract

To provide a hot-melt adhesive composition which has improved heat-resistant holding power, without impairing excellent advantages such as environmental performance, convenience and power saving of a hot-melt adhesive.SOLUTION: A hot-melt adhesive composition is provided, containing: block copolymer component (A) including an asymmetric styrenic block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2); and a terpene phenol-based tackifier resin (B). In the hot-melt adhesive, a mass ratio (a1 / a2) of the asymmetric styrenic block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60, and a content of the block copolymer component (A) in the hot-melt adhesive composition is 30 mass% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hot melt pressure-sensitive adhesive composition, and more particularly, to a hot melt pressure-sensitive adhesive composition containing a block copolymer component including an asymmetric styrene-based block copolymer and a styrene-conjugated diene diblock copolymer, and a terpene phenol-based tackifying resin. [Background technology]

[0002] Hot melt pressure sensitive adhesives are environmentally friendly as they do not use solvents, and are widely used in bookbinding, food packaging, sanitary materials, textiles, building materials, automotive, etc. In addition, they do not require a drying oven, which offers the advantage of convenience and labor savings, and the performance requirements for hot melt pressure sensitive adhesives are increasing day by day.

[0003] Among hot melt pressure sensitive adhesives, those containing styrene-conjugated diene block copolymers such as styrene-isoprene block copolymers or styrene-butadiene block copolymers have an excellent balance of initial tack, adhesive strength, and holding power, and are therefore used in hygiene materials such as adhesive tapes, disposable diapers, and sanitary napkins. These hot melt pressure sensitive adhesives usually contain a styrene-conjugated diene block copolymer and a tackifying resin, and optionally a softener (plasticizer) and stabilizer.

[0004] For example, in order to facilitate application at relatively low temperatures, extend the open time, and improve holding power in such hot melt pressure sensitive adhesives, a hot melt pressure sensitive adhesive composition has been proposed in which a tackifying resin is blended into a block copolymer composition obtained by blending, in a specific ratio, an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer in which two aromatic vinyl polymer blocks have different weight average molecular weights with an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having a different specific structure (Patent Document 1). Furthermore, for the purposes of facilitating application at relatively low temperatures, lengthening the open time, and improving holding power and tackiness, a hot melt pressure-sensitive adhesive composition has been proposed in which an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer in which two aromatic vinyl polymer blocks have different weight-average molecular weights is blended in a specific ratio with an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having a specific structure different from that of the aromatic vinyl polymer block copolymer to form a block copolymer composition, and a tackifier resin containing a specific amount of aromatic monomer units is blended with this (Patent Document 2). Furthermore, for the purpose of achieving both softener retention and die-cutting properties and improving tackiness in low-temperature environments, a hot-melt pressure-sensitive adhesive composition has been proposed in which an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer is blended with a block copolymer having a specific structure, and further a tackifier resin, a softener, and a wax are blended (Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2010 / 157507 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-254983 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-207127 Summary of the Invention [Problem to be solved by the invention]

[0006] Among the performance requirements for hot melt adhesives and adhesives, for example, In anticipation of applications for fixing components such as electronic parts and the like, there is a demand for performance that allows high holding power to be maintained even in high temperature environments (hereinafter referred to as heat-resistant holding power). However, the above-mentioned conventional hot-melt pressure-sensitive adhesive compositions have been insufficient in terms of heat-resistant holding power. Although the hot melt pressure-sensitive adhesive compositions described in Patent Documents 1 to 3 have been investigated for their holding power at 40°C, they do not have the ability to maintain high holding power even in a high temperature environment.

[0007] An object of the present invention is to provide a hot melt pressure-sensitive adhesive composition that has improved heat resistance retention without impairing the excellent advantages of hot melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor saving. [Means for solving the problem]

[0008] In view of the above circumstances, the present inventors have conducted extensive research and have found that a hot melt pressure-sensitive adhesive composition containing a block copolymer component (A) comprising an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2) in a specific mass ratio, and containing a terpene phenol-based tackifying resin (B) as a tackifying resin, can improve heat resistance retention without impairing the excellent advantages of hot melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor-saving, and have thus completed the present invention.

[0009] That is, the present invention provides a hot melt pressure-sensitive adhesive composition containing a block copolymer component (A) including an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), and a terpene phenol-based tackifying resin (B), the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60; The present invention relates to a hot melt pressure-sensitive adhesive composition, wherein the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 30% by mass or more.

[0010] It is preferable that the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 30% by mass or more and 50% by mass or less, and the content of the terpene phenol-based tackifying resin (B) in the hot melt pressure-sensitive adhesive composition is 4% by mass or more and 25% by mass or less.

[0011] The content of the terpene phenol tackifying resin (B) in the hot melt pressure-sensitive adhesive composition is preferably 10% by mass or more and 20% by mass or less.

[0012] Furthermore, it is preferable that the content of the terpene phenol-based tackifying resin (B) is 10 parts by mass or more and 70 parts by mass or less relative to 100 parts by mass of the block copolymer component (A).

[0013] The hot melt pressure-sensitive adhesive composition preferably further contains a paraffin oil-based plasticizer.

[0014] The paraffin oil-based plasticizer has a kinematic viscosity of 300 mm at 40°C. 2 / second or more is preferable. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a hot melt pressure-sensitive adhesive composition having improved heat resistance retention without impairing the excellent advantages of hot melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor saving. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Hot melt pressure sensitive adhesive composition] The present invention provides a hot melt pressure-sensitive adhesive composition comprising a block copolymer component (A) including an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), and a terpene phenol-based tackifying resin (B), the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60; The present invention relates to a hot melt pressure-sensitive adhesive composition, wherein the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 30% by mass or more.

[0017] Generally, a "pressure-sensitive adhesive" refers to a bonding material that adheres simply by contact and immediately exhibits practically usable adhesive strength without the need for a liquid-to-solid state change. In contrast, a bonding material that requires a liquid-to-solid state change to exhibit practically usable adhesive strength is called an "adhesive." To exhibit adhesive strength, adhesives require a process of changing from a liquid to a solid, such as solvent evaporation, cooling, or a chemical reaction, and therefore require substantial solidification time.

[0018] <Block copolymer component (A)> The block copolymer component (A) used in the present invention contains an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2).

[0019] The asymmetric styrene block copolymer (a1) is an asymmetric styrene block copolymer, and "asymmetric" means that the lengths of the styrene blocks at both ends are different. The "styrene block copolymer" is a block copolymer having at least a polymer block mainly composed of structural units derived from styrene and a polymer block mainly composed of structural units derived from a conjugated diene.

[0020] The polymer block mainly composed of structural units derived from styrene may contain not only styrene monomers but also structural units derived from styrene-based monomers other than styrene, as long as the effects of the present invention are not impaired. Examples of styrene-based monomers other than styrene include α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, pt-butylstyrene, 2,4-dimethylstyrene, vinylnaphthalene, and vinylanthracene. The styrene-based monomers other than styrene may be used alone or in combination of two or more.

[0021] Examples of the conjugated diene in the polymer block composed of structural units derived from a conjugated diene include butadiene, isoprene, chloroprene, 2,3-dimethylbutadiene, 1,3-pentadiene, and 1,3-hexadiene. Of these, butadiene and isoprene are preferred, with isoprene being particularly preferred. The conjugated dienes may be used alone or in combination of two or more.

[0022] Examples of the asymmetric styrene-based block copolymer (a1) include an asymmetric styrene-isoprene-styrene block copolymer (hereinafter also referred to as an asymmetric SIS) and an asymmetric styrene-butadiene-styrene block copolymer (hereinafter also referred to as an asymmetric SBS), and the asymmetric styrene-isoprene-styrene block copolymer is preferred.

[0023] The asymmetric styrene-based block copolymer (a1) may be used alone or in combination of two or more.

[0024] The asymmetric styrene-based block copolymer (a1) can be synthesized by a known method, for example, the method described in JP-A-08-505897.

[0025] The styrene content of the asymmetric styrene block copolymer (a1) is, for example, 1% by mass or more and 40% by mass or less, for example, 5% by mass or more and 35% by mass or less, for example, 10% by mass or more and 30% by mass or less, where the asymmetric styrene block copolymer (a1) is taken as 100% by mass. However, the range of the content can be appropriately adjusted as long as the effects of the present invention are not impaired. The range is 1% by mass, 2% by mass, 3% by mass, 4% by mass, 5% by mass, 6% by mass, 7% by mass, 8% by mass, 9% by mass, 10% by mass, 11% by mass, 12% by mass, 13% by mass, 14% by mass, 15% by mass, 16% by mass, 17% by mass, 18% by mass, 19% by mass, 20% by mass, 21% by mass, 22% by mass, 23% by mass. %, 24% by mass, 25% by mass, 26% by mass, 27% by mass, 28% by mass, 29% by mass, 30% by mass, 31% by mass, 32% by mass, 33% by mass, 34% by mass, 35% by mass, 36% by mass, 37% by mass, 38% by mass, 39% by mass, and 40% by mass. When the styrene content of the asymmetric styrene-based block copolymer (a1) is within this range, the hot-melt pressure-sensitive adhesive composition of the present invention can further improve the heat resistance holding power without compromising the excellent advantages of hot-melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor saving.

[0026] The styrene-conjugated diene diblock copolymer (a2) is a diblock copolymer formed by bonding a polymer block consisting of structural units derived at least mainly from styrene and a polymer block consisting of structural units derived from a conjugated diene.

[0027] The polymer block mainly composed of structural units derived from styrene may contain not only styrene monomers but also structural units derived from styrene-based monomers other than styrene within the range that does not impair the effects of the present invention, and those listed above as the asymmetric styrene-based block copolymer (a1) can be used.

[0028] As the conjugated diene in the polymer block comprising structural units derived from a conjugated diene, those exemplified above for the asymmetric styrene-based block copolymer (a1) can be used.

[0029] Examples of the styrene-conjugated diene diblock copolymer (a2) include a styrene-isoprene diblock copolymer (hereinafter also referred to as an SI diblock) and a styrene-butadiene diblock copolymer (hereinafter also referred to as an SB diblock), and the styrene-isoprene diblock copolymer is preferred.

[0030] The styrene-conjugated diene diblock copolymer (a2) may be used alone or in combination of two or more.

[0031] In the hot melt pressure-sensitive adhesive composition of the present invention, the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60, and preferably 30 / 70 to 40 / 60.

[0032] The styrene-conjugated diene diblock copolymer (a2) can be obtained, for example, by an anionic polymerization method, such as a method in which alkyllithium is used as a catalyst to sequentially polymerize a conjugated diene and styrene, a method in which a conjugated diene and styrene are polymerized separately and then bonded together by an appropriate method, or a method in which a conjugated diene and styrene monomer are mixed in advance and then polymerized.

[0033] The block copolymer component (A) used in the present invention can be prepared, for example, by separately producing an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2) and mixing them by a conventional method such as kneading or solution mixing. Alternatively, the asymmetric styrene-based block copolymer (a1) may be prepared by adding a styrene monomer to the copolymer, synthesizing the asymmetric styrene-based block copolymer (a1), and then recovering the mixture from the solvent. The latter preparation method may be, for example, the method described in JP 2015-67807 A.

[0034] The block copolymer component (A) used in the present invention may be a commercially available product, and examples thereof include, but are not limited to, the following. For example, "Quintac (registered trademark) 3190" manufactured by Zeon Corporation, "Quintac (registered trademark) 3390" manufactured by Zeon Corporation, "Quintac (registered trademark) SL-186" manufactured by Zeon Corporation, and "Quintac (registered trademark) SL-196" manufactured by Zeon Corporation can be used.

[0035] The content of the block copolymer component (A) is 30% by mass or more, for example, 30% by mass to 50% by mass, based on 100% by mass of the hot melt pressure-sensitive adhesive composition of the present invention. However, the content range can be adjusted appropriately as long as the effects of the present invention are not impaired. The range can be adjusted by arbitrarily combining the lower and upper limits from 30% by mass, 31% by mass, 32% by mass, 33% by mass, 34% by mass, 35% by mass, 36% by mass, 37% by mass, 38% by mass, 39% by mass, 40% by mass, 41% by mass, 42% by mass, 43% by mass, 44% by mass, 45% by mass, 46% by mass, 47% by mass, 48% by mass, 49% by mass, and 50% by mass. By ensuring that the content of the block copolymer component (A) is within this range, the hot melt pressure-sensitive adhesive composition of the present invention can further improve heat resistance retention without impairing the excellent advantages of hot melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor savings.

[0036] <Terpene phenol-based tackifying resin (B)> Examples of the terpene phenol-based tackifying resin (B) used in the present invention include terpene phenol resins obtained by reacting a terpene compound with a phenol compound by a known method, and hydrogenated resins thereof.

[0037] Examples of the terpene compounds include α-pinene, β-pinene, dipentene, limonene, camphene, etc., with α-pinene and β-pinene being preferred, and α-pinene being more preferred. These compounds may be used alone or in combination of two or more.

[0038] Examples of the phenolic compound include phenol, cresol, xylenol, bisphenol, etc., and phenol is preferred. These compounds may be used alone or in combination of two or more.

[0039] The terpene phenol-based tackifying resin (B) used in the present invention preferably has a softening point of 100° C. or higher and 170° C. or lower, and more preferably 125° C. or higher and 150° C. or lower. In this specification, the softening point is measured in accordance with JIS K6863 (1994).

[0040] The terpene phenol-based tackifying resin (B) used in the present invention may be a commercially available product, examples of which include, but are not limited to, the following. For example, Yasuhara Chemical Co., Ltd.'s "YS Polyster U130" (softening point 130±5°C), Yasuhara Chemical Co., Ltd.'s "YS Polyster U115" (softening point 115±5°C), Yasuhara Chemical Co., Ltd.'s "YS Polyster T160" (softening point 160±5°C), Yasuhara Chemical Co., Ltd.'s "YS Polyster T130" (softening point 130±5°C), Yasuhara Chemical Co., Ltd.'s "YS Polyster T115" (softening point 115±5°C), Yasuhara Chemical Co., Ltd.'s "YS Polyster T100" (softening point 100±5°C), Yasuhara Chemical Co., Ltd.'s "YS Polyster S145" (softening point 145±5°C), Yasuhara Chemical Co., Ltd.'s "YS Polyster G150" (softening point 150 ... "YS Polyster G125" (softening point 125±5°C) manufactured by Yasuhara Chemical Co., Ltd., "YS Polyster N125" (softening point 125±5°C) manufactured by Yasuhara Chemical Co., Ltd., "YS Polyster K140" (softening point 140±5°C) manufactured by Yasuhara Chemical Co., Ltd., "YS Polyster K125" (softening point 125±5°C) manufactured by Yasuhara Chemical Co., Ltd., "YS Polyster TH130" (softening point 130±5°C) manufactured by Yasuhara Chemical Co., Ltd., "YS Polyster UH115" (softening point 115±5°C) manufactured by Yasuhara Chemical Co., Ltd., "Tamanol (registered trademark) 803L" (softening point 145°C or higher and 160°C or lower) manufactured by Arakawa Chemical Industries, Ltd., and "Tamanol (registered trademark) 901" (softening point 125°C or higher and 135°C or lower) manufactured by Arakawa Chemical Industries, Ltd. can be used. These may be used alone or in combination of two or more.

[0041] The content of the terpene phenol-based tackifying resin (B) is, for example, 4% by mass or more and 25% by mass or less, based on the total mass of the hot-melt pressure-sensitive adhesive composition of the present invention. However, the content range can be appropriately adjusted as long as the effects of the present invention are not impaired. This range can be adjusted by arbitrarily combining the lower and upper limits from 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, and 25% by mass, relative to 100% by mass of the hot-melt pressure-sensitive adhesive composition of the present invention. By ensuring that the content of the terpene phenol-based tackifying resin (B) is within this range, the hot-melt pressure-sensitive adhesive composition of the present invention can further improve its heat resistance retention without impairing the excellent advantages of hot-melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor-saving. Within the above range, the content of the terpene phenol-based tackifying resin (B) in the hot-melt pressure-sensitive adhesive composition of the present invention is preferably in the range of 10% by mass or more and 20% by mass or less. By ensuring that the content is within this range, deterioration of adhesive strength over time can be further suppressed, and the hot-melt pressure-sensitive adhesive composition of the present invention can be particularly suitably used in pressure-sensitive adhesive tape applications such as pressure-sensitive adhesive sheets, pressure-sensitive adhesive labels, protective films, masking tapes, and process tapes.

[0042] Furthermore, the terpene phenol-based tackifying resin (B) is contained in an amount of, for example, 10 to 70 parts by mass per 100 parts by mass of the block copolymer component (A). However, the content range can be appropriately adjusted as long as the effects of the present invention are not impaired. The ranges are 10 parts by mass, 11 parts by mass, 12 parts by mass, 13 parts by mass, 14 parts by mass, 15 parts by mass, 16 parts by mass, 17 parts by mass, 18 parts by mass, 19 parts by mass, 20 parts by mass, 21 parts by mass, 22 parts by mass, 23 parts by mass, 24 parts by mass, 25 parts by mass, 26 parts by mass, 27 parts by mass, 28 parts by mass, 29 parts by mass, 30 parts by mass, 31 parts by mass, 32 parts by mass, 33 parts by mass, 34 parts by mass, 35 parts by mass, 36 parts by mass, 37 parts by mass, 38 parts by mass, 39 parts by mass, 40 parts by mass, and 41 parts by mass per 100 parts by mass of the block copolymer component (A). The amount can be adjusted by arbitrarily combining the lower and upper limits from among 41 parts by mass, 42 parts by mass, 43 parts by mass, 44 parts by mass, 45 parts by mass, 46 parts by mass, 47 parts by mass, 48 ​​parts by mass, 49 parts by mass, 50 parts by mass, 51 parts by mass, 52 parts by mass, 53 parts by mass, 54 parts by mass, 55 parts by mass, 56 parts by mass, 57 parts by mass, 58 parts by mass, 59 parts by mass, 60 parts by mass, 61 parts by mass, 62 parts by mass, 63 parts by mass, 64 parts by mass, 65 parts by mass, 66 parts by mass, 67 parts by mass, 68 parts by mass, 69 parts by mass, and 70 parts by mass. For example, the amount can be 10 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the block copolymer component (A), such as 55 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the block copolymer component (A). By setting the content of the terpene phenol-based tackifying resin (B) to 10 parts by mass or more and 70 parts by mass or less per 100 parts by mass of the block copolymer component (A), the hot melt pressure-sensitive adhesive composition of the present invention can further improve heat resistance retention without compromising the excellent advantages of hot melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor saving.

[0043] The hot melt pressure-sensitive adhesive composition of the present invention may contain a tackifying resin other than a terpene phenol type, as long as the effect of the present invention is not impaired. Examples of tackifying resins other than phenol-based resins include phenolic resins, modified phenolic resins, xylene phenolic resins, xylene resins, cyclopentadiene-phenolic resins, aliphatic petroleum resins, hydrogenated aliphatic petroleum resins, aromatic petroleum resins, hydrogenated aromatic petroleum resins, aliphatic / aromatic copolymer petroleum resins, hydrogenated aliphatic / aromatic copolymer petroleum resins, phenol-modified petroleum resins, rosin ester resins, hydrogenated rosin ester resins, low-molecular-weight polystyrene resins, terpene resins, and hydrogenated terpene resins, with hydrogenated aromatic petroleum resins, hydrogenated aliphatic / aromatic copolymer petroleum resins, and hydrogenated rosin ester resins being preferred. These may be used alone or in combination of two or more.

[0044] Aliphatic petroleum resins and hydrogenated aliphatic petroleum resins include C5 petroleum resins, C5 partially hydrogenated petroleum resins, and C5 fully hydrogenated petroleum resins. Aromatic petroleum resins and hydrogenated aromatic petroleum resins include C9 petroleum resins, C9 partially hydrogenated petroleum resins, and C9 fully hydrogenated petroleum resins. Aliphatic / aromatic copolymer petroleum resins and hydrogenated aliphatic / aromatic copolymer petroleum resins include C5 / C9 petroleum resins, C5 / C9 partially hydrogenated petroleum resins, and C5 / C9 fully hydrogenated petroleum resins. Among these specific examples, C9 fully hydrogenated petroleum resins and C5 / C9 partially hydrogenated petroleum resins are preferred. These may be used alone or in combination of two or more. C5 petroleum resins are resins obtained by cationic polymerization of unsaturated monomers such as isoprene, 1,3-pentadiene, methylbutene, pentene, and cyclopentadiene, which are petroleum fractions having 4 to 5 carbon atoms (C5 fractions). C9 petroleum resins are resins obtained by cationic polymerization of monomers such as vinyltoluene, alkylstyrene, and indene, which are petroleum fractions having 8 to 10 carbon atoms (C9 fractions). C5 / C9 petroleum resins are resins obtained by copolymerizing the above C5 fraction and the above C9 fraction.

[0045] Commercially available C9 fully hydrogenated petroleum resins include Arakawa Chemical Industries, Ltd.'s "Alcon (registered trademark) P-100" (softening point 100°C±5°C), Arakawa Chemical Industries, Ltd.'s "Alcon (registered trademark) P-115" (softening point 115°C±5°C), Arakawa Chemical Industries, Ltd.'s "Alcon (registered trademark) P-125" (softening point 125°C±5°C), and Arakawa Chemical Industries, Ltd.'s "Alcon (registered trademark) P-140" (softening point 140°C±5°C). Furthermore, an example of a commercially available C5 / C9 partially hydrogenated petroleum resin is "Imarv (registered trademark) S-100" (softening point 100°C) manufactured by Idemitsu Kosan Co., Ltd. Furthermore, an example of the hydrogenated rosin ester resin is "Foralin 5020F" manufactured by Eastman Chemical Co., Ltd.

[0046] When the hot-melt pressure-sensitive adhesive composition of the present invention also contains a tackifying resin other than a terpene phenol-based resin, the content of the tackifying resin is, for example, 15% by mass to 40% by mass, e.g., 25% by mass to 40% by mass, based on the total mass of the hot-melt pressure-sensitive adhesive composition of the present invention. However, the content range can be appropriately adjusted as long as the effects of the present invention are not impaired. The range can be adjusted by arbitrarily combining the lower and upper limits from 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, and 40% by mass, relative to 100% by mass of the hot-melt pressure-sensitive adhesive composition of the present invention. By ensuring that the content of the non-terpene phenol-based tackifying resin is within this range, the hot melt pressure-sensitive adhesive composition of the present invention can further improve heat resistance retention without compromising the excellent advantages of hot melt pressure-sensitive adhesives, such as environmental friendliness, convenience, and labor saving.

[0047] <Plasticizer> The hot-melt pressure-sensitive adhesive composition of the present invention may contain a plasticizer. Examples of such plasticizers include paraffin oil-based plasticizers, benzoate ester plasticizers, organic ester plasticizers, and phosphoric acid plasticizers, with paraffin oil-based plasticizers being preferred. Examples of the paraffin oil-based plasticizers include naphthenic process oils, white mineral oils, mineral oils, paraffin wax, and liquid paraffin, with naphthenic process oils and paraffin wax being preferred. These may be used alone or in combination of two or more.

[0048] As the paraffin oil-based plasticizer, commercially available products can be used, examples of which include, but are not limited to, the following: For example, "Diana Process Oil PW-90" manufactured by Idemitsu Kosan Co., Ltd. and "Diana Process Oil PW-380" manufactured by Idemitsu Kosan Co., Ltd. can be used.

[0049] The paraffin oil-based plasticizer has a kinematic viscosity of 300 mm at 40°C. 2 The kinematic viscosity at 40°C is measured in accordance with the JIS K 2283 kinematic viscosity test. The paraffin oil-based plasticizer preferably has a kinematic viscosity of 300 mm / s or more at 40°C. 2 / second or more, the heat resistance retention can be further improved.

[0050] When a plasticizer is used in the hot melt pressure-sensitive adhesive composition of the present invention, the content of the plasticizer is, for example, 0.001% by mass or more and 30% by mass or less, for example, 5% by mass or more and 25% by mass or less, for example, 10% by mass or more and 20% by mass or less, relative to 100% by mass of the hot melt pressure-sensitive adhesive composition of the present invention.

[0051] <Other additives> In addition to the above-mentioned components, the hot-melt pressure-sensitive adhesive composition of the present invention may contain additives commonly used in pressure-sensitive adhesives, etc., within the scope of not impairing the effects of the present invention. Examples of such additives include, but are not limited to, antioxidants, ultraviolet absorbers, fillers, pigments, dyes, antistatic agents, flame retardants, antifoaming agents, antibacterial agents, deodorizers, etc.

[0052] Examples of antioxidants include naphthylamine-based, p-phenylenediamine-based, quinoline-based, phenol-based, hindered phenol-based, and hindered amine-based antioxidants, and among these, hindered phenol-based antioxidants are preferably used. These can be used alone or in combination of two or more. An example of a commercially available hindered phenol-based antioxidant is "EVANOX (registered trademark) 10" manufactured by Everspring Chemical Company.

[0053] When other additives are used in the hot melt pressure-sensitive adhesive composition of the present invention, the content thereof is, for example, 0.001% by mass or more and 5% by mass or less, for example, 0.01% by mass or more and 3% by mass or less, relative to 100% by mass of the hot melt pressure-sensitive adhesive composition of the present invention.

[0054] Preferred examples of the hot melt pressure sensitive adhesive composition of the present invention are as follows.

[0055] A hot melt pressure-sensitive adhesive composition comprising a block copolymer component (A) including an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), a terpene phenol-based tackifying resin (B), and a tackifying resin other than a terpene phenol-based resin, the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60; the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 45% by mass or more and 50% by mass or less; the content of the terpene phenol-based tackifying resin (B) in the hot-melt pressure-sensitive adhesive composition is 9.5% by mass or more and 20% by mass or less; The hot melt pressure-sensitive adhesive composition, wherein the content of the non-terpene phenol tackifier resin in the hot melt pressure-sensitive adhesive composition is 30% by mass or more and 40% by mass or less.

[0056] A hot melt pressure-sensitive adhesive composition comprising a block copolymer component (A) containing an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), a terpene phenol-based tackifying resin (B), a tackifying resin other than a terpene phenol-based resin, and a paraffin oil-based plasticizer, the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60; the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 40% by mass or more and 45% by mass or less; the content of the terpene phenol-based tackifying resin (B) in the hot-melt pressure-sensitive adhesive composition is 10% by mass or more and 20% by mass or less; the content of the non-terpene phenol tackifier resin in the hot-melt pressure-sensitive adhesive composition is 20% by mass or more and 30% by mass or less; The hot-melt pressure-sensitive adhesive composition, wherein the content of the paraffin oil-based plasticizer in the hot-melt pressure-sensitive adhesive composition is 10% by mass or more and 15% by mass or less.

[0057] A hot melt pressure-sensitive adhesive composition comprising a block copolymer component (A) containing an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), a terpene phenol-based tackifying resin (B), a tackifying resin other than a terpene phenol-based resin, and a paraffin oil-based plasticizer, the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60; the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 30% by mass or more and 40% by mass or less; the content of the terpene phenol-based tackifying resin (B) in the hot-melt pressure-sensitive adhesive composition is 4% by mass or more and 16% by mass or less; the content of the non-terpene phenol-based tackifier resin in the hot-melt pressure-sensitive adhesive composition is 30% by mass or more and 45% by mass or less; The hot-melt pressure-sensitive adhesive composition, wherein the content of the paraffin oil-based plasticizer in the hot-melt pressure-sensitive adhesive composition is 10% by mass or more and 15% by mass or less.

[0058] A hot melt pressure-sensitive adhesive composition comprising a block copolymer component (A) containing an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), a terpene phenol-based tackifying resin (B), a tackifying resin other than a terpene phenol-based resin, and a paraffin oil-based plasticizer, the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60 to 40 / 60; the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 35% by mass or more and 40% by mass or less; the content of the terpene phenol-based tackifying resin (B) in the hot-melt pressure-sensitive adhesive composition is 15% by mass or more and 20% by mass or less; the content of the non-terpene phenol tackifier resin in the hot melt pressure-sensitive adhesive composition is 25% by mass or more and 30% by mass or less; The hot-melt pressure-sensitive adhesive composition, wherein the content of the paraffin oil-based plasticizer in the hot-melt pressure-sensitive adhesive composition is 15% by mass or more and 20% by mass or less.

[0059] A hot melt pressure-sensitive adhesive composition comprising a block copolymer component (A) containing an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), a terpene phenol-based tackifying resin (B), a tackifying resin other than a terpene phenol-based resin, and a paraffin oil-based plasticizer, the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60 to 40 / 60; the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 30% by mass or more and 35% by mass or less; the content of the terpene phenol-based tackifying resin (B) in the hot-melt pressure-sensitive adhesive composition is 20% by mass or more and 25% by mass or less; the content of the non-terpene phenol tackifier resin in the hot melt pressure-sensitive adhesive composition is 25% by mass or more and 30% by mass or less; The hot-melt pressure-sensitive adhesive composition, wherein the content of the paraffin oil-based plasticizer in the hot-melt pressure-sensitive adhesive composition is 15% by mass or more and 20% by mass or less.

[0060] In the present invention, heat-resistant holding power means the ability to maintain high holding power even in a high-temperature environment, and high temperature refers to, for example, 100°C or higher, for example, 90°C or higher, for example, 80°C or higher, for example, 70°C or higher, or for example, 60°C or higher. Furthermore, "maintaining holding power" specifically refers to a process in which the hot-melt pressure-sensitive adhesive composition of the present invention is applied to a general-purpose substrate for pressure-sensitive adhesive tape or the like to prepare a pressure-sensitive adhesive tape, and the pressure-sensitive adhesive tape is then attached to a general-purpose stainless steel plate, for example, so that the adhesive area is 25 mm × 25 mm, to prepare a test specimen with the pressure-sensitive adhesive tape attached thereto; one end of the stainless steel plate is fastened with a fastener at the above-mentioned temperature so that the test specimen hangs down vertically; and after leaving it for, for example, 10 minutes or more, a load is applied to the lower end of the pressure-sensitive adhesive tape attached to the test specimen with a weight of, for example, 500 g, for example, 1 kg, for example, 2 kg; and the time until the pressure-sensitive adhesive tape slips off the stainless steel plate due to this load is, for example, 1 hour or more, for example, 2 hours or more, for example, 5 hours or more, for example, 6 hours or more, for example, 24 hours or more, for example, 48 hours or more, for example, 96 hours or more, for example, 168 hours or more, for example, 200 hours or more. The time it takes for the adhesive tape to slip off the stainless steel plate can vary within the above-mentioned range of time depending on the temperature range referred to as the high temperature, the time it is left at a high temperature within the above-mentioned temperature range, and the weight of the weight applied.

[0061] <Method for producing hot melt pressure sensitive adhesive composition> The hot-melt pressure-sensitive adhesive composition can be produced by a known method, and the production method is not particularly limited. For example, a method in which the block copolymer component (A), the terpene phenol tackifying resin (B), and optionally a tackifying resin other than the terpene phenol, the plasticizer, and the various additives are charged into a stirring kneader equipped with a heating device and kneaded while heating is performed may be mentioned.

[0062] The heating temperature during kneading is not particularly limited as long as it is a temperature equal to or higher than the softening points of the block copolymer component (A) and the terpene phenol-based tackifying resin (B) used, and is preferably 100° C. to 200° C., more preferably 120° C. to 180° C. The kneading time is not particularly limited as long as the mixture becomes homogeneous, and is, for example, 5 minutes to 300 minutes, 30 minutes to 180 minutes, or 60 minutes to 120 minutes.

[0063] <Adhesive body and its manufacturing method> An adhesive body can be formed by a method including a coating step of applying the hot melt pressure-sensitive adhesive composition of the present invention to one surface of a first substrate to form a pressure-sensitive adhesive layer, and a bonding step of bonding the first substrate and a second substrate via the pressure-sensitive adhesive layer.

[0064] The substrates used as the first substrate and the second substrate are not particularly limited, and examples thereof include wood-based materials such as paper and wood; porous substrates made from natural materials such as cellulose-based materials and cotton-based materials, and fabric materials such as nonwoven fabrics; plastic materials such as polyvinyl chloride resin, polyolefin (polypropylene, polyethylene, ethylene-propylene copolymer, etc.), polyurethane, polyester, epoxy, nylon, polycarbonate, acrylic, ABS, polycarbonate (PC) ABS, etc.; rubber materials such as natural rubber and synthetic rubber; metal materials such as aluminum, iron, stainless steel, etc.; and inorganic materials such as ceramics. The shape of each substrate is not particularly limited and may be, for example, a sheet, foil, plate, molded product, etc. Furthermore, each substrate may be made of only one type of material, or may be made of two or more types of material.

[0065] In the coating step, known methods can be used to coat the substrate, such as spiral spray coating, slot coater coating, curtain spray coating, roll coater coating, omega coating, dot coating, and bead coating. The temperature for application to the substrate can be appropriately selected depending on the viscosity of the hot-melt pressure-sensitive adhesive composition, and the composition can be applied in a molten state by heating at a temperature of 140° C. or higher and 200° C. or lower. The application step may also be a step of applying the composition to a release film or release paper and then transferring it to the first substrate. The precoated substrate (first substrate containing a pressure-sensitive adhesive layer) obtained after the coating step may be directly subjected to the next bonding step, or may be stored before being subjected to the next bonding step. During storage, a release film or release paper may be adhered to the exposed pressure-sensitive adhesive layer. When the surface of the first substrate not having the pressure-sensitive adhesive layer is a surface treated with a release film, release paper, or release coating such as silicone, the precoated substrate may be rolled into a cylindrical shape and stored. The coating step may also be a step of coating the hot melt pressure-sensitive adhesive composition of the present invention onto a release film or release paper, then further overlapping a release film or release paper to sandwich the hot melt pressure-sensitive adhesive composition of the present invention between the release films or release papers to produce a so-called substrate-less double-sided tape, and then peeling off one of the release films or release papers to attach the precoated substrate to a first substrate. In this case, the other release film or release paper is adhered to the pressure-sensitive adhesive layer of the precoated substrate, and in the adhesion step described below, the other release film or release paper is peeled off and the precoated substrate is adhered to a second substrate.

[0066] The bonding step is a step of pressure-bonding the precoated substrate and the second substrate. Since the hot-melt pressure-sensitive adhesive layer formed from the hot-melt pressure-sensitive adhesive composition of the present invention has adhesiveness even when not heated, the bonding step does not require a heating step, and the bonding can also be achieved by pressure-bonding. If necessary, the hot-melt pressure-sensitive adhesive layer may be re-melted by heat activation. Heat activation may be performed by, for example, heating, ultrasonic waves, high frequency waves, microwaves, or the like, but is not particularly limited. When reactivation is performed, it may be performed immediately before, simultaneously with, or after pressure bonding of the precoated substrate and the second substrate. When heat activation is performed, the temperature should be such that the hot melt pressure-sensitive adhesive layer melts, for example, the surface temperature of the hot melt pressure-sensitive adhesive layer is 100°C or higher and 200°C or lower, preferably 100°C or higher and 180°C or lower.

[0067] The pressure-bonding method is not particularly limited, and may be a known method such as a known press pressure-bonding method, vacuum forming method, etc. Furthermore, since the hot-melt pressure-sensitive adhesive composition of the present invention can be applied and bonded without heating, pressure-bonding can be achieved by a simple method such as using fingers, a trowel, or a roller without using any equipment.

[0068] The hot melt pressure-sensitive adhesive composition of the present invention can be used in a variety of applications, including pressure-sensitive adhesive tape applications such as pressure-sensitive adhesive sheets, pressure-sensitive adhesive labels, protective films, masking tapes, and process tapes; applications for fixing automobile interior materials and electronic components; applications for processing clothing and other fibers; applications for joining nonwoven fabrics and other fabric materials; and applications for joining plastic parts together.

[0069] Adhesive tapes such as adhesive sheets, adhesive labels, protective films, masking tapes, and process tapes can be produced by known methods, and as described above, a hot melt adhesive composition is applied to one side of a substrate, which is then wound up in the form of a tape log, and cut to an arbitrary width, thereby forming the tape into a tape shape. When the hot melt pressure-sensitive adhesive composition of the present invention is used as a pressure-sensitive adhesive layer of a pressure-sensitive adhesive sheet, a pressure-sensitive adhesive label, a protective film, a masking tape, a tape for processes, or the like, a method may be employed in which a solvent is added to the hot melt pressure-sensitive adhesive composition of the present invention, the composition is coated, and the solvent is then thoroughly removed in a drying oven to form a pressure-sensitive adhesive layer.

[0070] The adhesive sheets, adhesive labels, protective films, masking tapes, process tapes and other adhesive tapes produced using the hot melt adhesive composition of the present invention can be easily adhered to the above-mentioned substrates by the above-mentioned methods. [Example]

[0071] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0072] The abbreviations have the following meanings: (1) Block copolymer component 3190: Thermoplastic elastomer containing an asymmetric styrene-isoprene-styrene block copolymer (asymmetric SIS) and a styrene-isoprene diblock copolymer (SI diblock) [the mass ratio of the asymmetric SIS to the SI diblock (asymmetric SIS / SI diblock) is 40 / 60, and the styrene content of the asymmetric SIS is 30% by mass relative to 100% by mass of the asymmetric SIS] (Zeon Corporation, Quintac (registered trademark) 3190) 3433N: Thermoplastic elastomer containing a symmetric styrene-isoprene-styrene block copolymer (hereinafter also referred to as symmetric SIS) and a styrene-isoprene diblock copolymer (SI diblock) [the mass ratio of the symmetric SIS to the SI diblock (symmetric SIS / SI diblock) is 44 / 56, and the styrene content of the symmetric SIS is 18% by mass relative to 100% by mass of the symmetric SIS] (Quintac (registered trademark) 3433N, manufactured by Zeon Corporation). D1161JSP: A thermoplastic elastomer containing a symmetric styrene-isoprene-styrene block copolymer (symmetric SIS) and a styrene-isoprene diblock copolymer (SI diblock) [the mass ratio of the symmetric SIS to the SI diblock (symmetric SIS / SI diblock) is 81 / 19, and the styrene content of the symmetric SIS is 15% by mass relative to 100% by mass of the symmetric SIS] (Kraton (registered trademark) D1161JSP, manufactured by Kraton Polymer Japan Co., Ltd.) D1118ET: A thermoplastic elastomer containing a symmetric styrene-butadiene-styrene block copolymer (hereinafter also referred to as symmetric SBS) and a styrene-butadiene diblock copolymer (hereinafter also referred to as SB diblock) [the mass ratio of the symmetric SBS to the SB diblock (symmetric SBS / SB diblock) is 22 / 78, and the styrene content of the symmetric SBS is 33 mass% relative to 100 mass% of the symmetric SBS] (Kraton (registered trademark) D1118ET, manufactured by Kraton Polymer Japan Co., Ltd.) (2) Terpene phenol tackifying resin 803L: Terpene phenol resin (manufactured by Arakawa Chemical Industries, Ltd., Tamanor (registered trademark) 803L) (softening point 145℃ or higher and 160℃ or lower) G150: Terpene phenol resin (Yasuhara Chemical Co., Ltd., YS Polyster G150) (softening point 150±5°C) G125: Terpene phenol resin (Yasuhara Chemical Co., Ltd., YS Polyster G125) (softening point 125±5°C) K125: Terpene phenol resin (Yasuhara Chemical Co., Ltd., YS Polyster K125) (softening point 125±5°C) (3) Tackifying resins other than terpene phenolic resins P-100: Hydrogenated petroleum resin (manufactured by Arakawa Chemical Industries, Ltd., Alcon (registered trademark) P-100, softening point 100±5°C) P-115: Hydrogenated petroleum resin (manufactured by Arakawa Chemical Industries, Ltd., Alcon (registered trademark) P-115, softening point 115±5°C) P-125: Hydrogenated petroleum resin (manufactured by Arakawa Chemical Industries, Ltd., Alcon (registered trademark) P-125, softening point 125±5°C) P-140: Hydrogenated petroleum resin (manufactured by Arakawa Chemical Industries, Ltd., Alcon (registered trademark) P-140, softening point 140±5°C) S-100: Hydrogenated petroleum resin (Imave (registered trademark) S-100, manufactured by Idemitsu Kosan Co., Ltd., softening point 100°C) 5020F: Hydrogenated rosin methyl ester (Eastman Chemical Co., Foralin 5020F) (4) Plasticizer PW-90: Paraffin oil (Idemitsu Kosan Co., Ltd., Diana Process Oil PW-90) PW-380: Paraffin oil (Idemitsu Kosan Co., Ltd., Diana Process Oil PW-380) (5) Antioxidants E10: Hindered phenol-based antioxidant (Everspring Chemical Company, Evanox (registered trademark) 10)

[0073] [Example 1] Into a stirring kneader equipped with a heating device (manufactured by Moriyama Seisakusho Co., Ltd., SV1-1), 47.1 parts by mass of 3190, 9.8 parts by mass of 803L, 14.5 parts by mass of P-115, 21.6 parts by mass of S-100, 3.1 parts by mass of 5020F, and 3.9 parts by mass of E10 (total 1000 g) were charged, the temperature of the heating device was set to 160°C, and the mixture was kneaded while heating for 2 hours to obtain a uniform hot-melt pressure-sensitive adhesive composition (Example 1).

[0074] [Examples 2 to 11] Uniform hot-melt pressure-sensitive adhesive compositions (Examples 2 to 11) were obtained in the same manner as in Example 1, except that the compositions were changed to those shown in Table 1 below and the temperature of the heating device was set to 180° C. The content of each component in the composition in Table 1 below is expressed in parts by mass.

[0075] [Comparative Examples 1 to 4] Uniform hot-melt pressure-sensitive adhesive compositions (Comparative Examples 1 to 4) were obtained in the same manner as in Example 1, except that the compositions were changed to those shown in Table 2 below and the temperature setting of the heating device was changed to 180° C. The content of each component in the composition in Table 2 below is expressed in parts by mass.

[0076] [Table 1]

[0077] [Table 2]

[0078] <Evaluation of compatibility> When the appearance of the produced hot-melt pressure-sensitive adhesive compositions of Examples 1 to 11 and Comparative Examples 1 to 4 was visually transparent or uniformly milky, the compatibility was evaluated as ◯, and when it was non-uniform, the compatibility was evaluated as ×. The evaluation results are shown in Table 3 below.

[0079] <Heat resistance retention evaluation test> The heat resistance retention evaluation test was carried out with reference to JIS Z 0237:2022 and JIS Z1541:2009. Each of the hot-melt pressure-sensitive adhesive compositions of Examples 1 to 11 and Comparative Examples 1 to 4 was applied to a release paper placed on a hot plate heated to 180°C using a Baker applicator (YBA-1, manufactured by Yoshimitsu Seiki Co., Ltd.) to a thickness of 25 μm to form a hot-melt pressure-sensitive adhesive layer. The formed hot-melt pressure-sensitive adhesive layer was transferred to a 25 μm-thick polyethylene terephthalate (PET) film to prepare a pressure-sensitive adhesive tape. At room temperature (23±2°C), the pressure-sensitive adhesive tape was cut to a width of 25 mm and a length of 50 mm. This was then attached to a degreased stainless steel plate (SUS-BA plate, 1 mm thick) to give an adhesive area of ​​25 mm × 25 mm, and a 2 kg roller was rolled back and forth twice to press the tape together, producing a test specimen. One end of the SUS plate was fastened with a fastener so that the test specimen hung vertically in an incubator at 80°C, and after curing for 30 minutes, a load was applied to the lower end of the adhesive tape in an incubator at 80°C with a 1 kg weight, and the time until the adhesive tape slipped off the SUS plate due to this load was measured. The adhesive tape that did not slip off even after 24 hours or more was evaluated as ⊚, the adhesive tape that slipped off in 1 hour or more but less than 24 hours was evaluated as ◯, and the adhesive tape that slipped off in less than 1 hour was evaluated as ×. The evaluation results are shown in Table 3 below.

[0080] <Adhesion evaluation test> The adhesive strength evaluation test was carried out with reference to JIS Z 0237:2022. Each of the hot-melt pressure-sensitive adhesive compositions of Examples 1 to 11 and Comparative Examples 1 to 4 was applied to a release paper placed on a hot plate heated to 180°C using a Baker applicator (YBA-1, manufactured by Yoshimitsu Seiki Co., Ltd.) to a thickness of 25 μm to form a hot-melt pressure-sensitive adhesive layer. The formed hot-melt pressure-sensitive adhesive layer was transferred to a 25 μm-thick PET film to prepare a pressure-sensitive adhesive tape. At room temperature (23±2°C), the pressure-sensitive adhesive tape was cut to a width of 25 mm and a length of 130 mm, and the tape was attached to a degreased stainless steel plate (SUS-BA plate, thickness 1 mm) to a length of approximately 60 mm, taking care not to trap air bubbles, and a test specimen was prepared by pressing the tape back and forth twice using a 2 kg roller. After leaving this test piece at room temperature for 30 minutes, the adhesive tape was peeled off the SUS plate at a rate of 300 mm / min. The first 25 mm of peeling was ignored, and the peel force (N) for the next 50 mm was measured using an autograph (Shimadzu Corporation, AGS-J). The average peel force was calculated and used as the adhesive strength (N / 25 mm). The results are shown in Table 3 below.

[0081] <Loop Tack Evaluation Test> The hot-melt pressure-sensitive adhesive compositions of Examples 2 to 11 and Comparative Examples 1 to 4 were applied to a release paper placed on a hot plate heated to 180°C using a Baker applicator (YBA-1, manufactured by Yoshimitsu Seiki Co., Ltd.) to a thickness of 25 μm to form a hot-melt pressure-sensitive adhesive layer. The formed hot-melt pressure-sensitive adhesive layer was transferred to a 25 μm-thick PET film to prepare a pressure-sensitive adhesive tape. At room temperature (23±2°C), the pressure-sensitive adhesive tape was cut to a width of 25 mm and a length of 120 mm. The tape was then wound into a loop with a circumference of 10 mm, with the surface of the hot-melt pressure-sensitive adhesive layer (the surface coated with the hot-melt pressure-sensitive adhesive composition) facing outward. The back surface (non-adhesive surface) of the pressure-sensitive adhesive layer at the end was then overlapped to prepare a loop-shaped test specimen. The end of the test specimen was gripped with the gripping tool of an autograph (AGS-J, manufactured by Shimadzu Corporation) and attached to the upper side of a testing machine, and a flat stainless steel plate (SUS-BA plate, 1 mm thick) was attached to the lower side of the testing machine. The specimen was then lowered at a speed of 300 mm / min until the distance between the clamping position at the end and the stainless steel plate reached 20 mm and the loop came into contact with the SUS plate and spread out. Immediately thereafter, the specimen was peeled off from the SUS plate at a speed of 300 mm / min, and the resistance force (N) at this time was measured and recorded as the loop tack. The results are shown in Table 3 below.

[0082] [Table 3]

[0083] From the results shown in Table 3, the hot-melt pressure-sensitive adhesive composition of Example 1 of the present invention exhibited excellent adhesive strength and high performance in heat resistance retention. Furthermore, the hot-melt pressure-sensitive adhesive compositions of Examples 2 to 11 of the present invention exhibited excellent adhesive strength and loop tack, as well as high performance in heat resistance retention. In contrast, the hot-melt pressure-sensitive adhesive composition of Comparative Example 1, which did not contain the block copolymer component (A) used in the present invention and did not contain the terpene phenol tackifying resin (B) used in the present invention, exhibited poor heat resistance retention. Furthermore, the hot melt pressure-sensitive adhesive compositions of Comparative Examples 3 and 4, which contained the block copolymer component (A) used in the present invention but did not contain the terpene phenol-based tackifier resin (B) used in the present invention, exhibited poor heat resistance retention. Furthermore, the hot melt pressure-sensitive adhesive composition of Comparative Example 2, which contained the terpene phenol-based tackifier resin (B) used in the present invention but did not contain the block copolymer component (A) used in the present invention, exhibited poor heat resistance retention.

Claims

1. A hot melt pressure-sensitive adhesive composition comprising a block copolymer component (A) including an asymmetric styrene-based block copolymer (a1) and a styrene-conjugated diene diblock copolymer (a2), and a terpene phenol-based tackifying resin (B), the mass ratio (a1 / a2) of the asymmetric styrene-based block copolymer (a1) to the styrene-conjugated diene diblock copolymer (a2) is 22 / 78 to 40 / 60; The hot melt pressure-sensitive adhesive composition has a content of the block copolymer component (A) of 30% by mass or more.

2. 2. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the content of the block copolymer component (A) in the hot melt pressure-sensitive adhesive composition is 30% by mass or more and 50% by mass or less, and the content of the terpene phenol-based tackifying resin (B) in the hot melt pressure-sensitive adhesive composition is 4% by mass or more and 25% by mass or less.

3. 3. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the content of the terpene phenol-based tackifier resin (B) in the hot melt pressure-sensitive adhesive composition is 10% by mass or more and 20% by mass or less.

4. 2. The hot melt pressure-sensitive adhesive composition according to claim 1, wherein the content of the terpene phenol-based tackifier resin (B) is 10 parts by mass or more and 70 parts by mass or less relative to 100 parts by mass of the block copolymer component (A).

5. The hot melt pressure-sensitive adhesive composition according to claim 1, further comprising a paraffin oil-based plasticizer.

6. The paraffin oil-based plasticizer has a kinematic viscosity of 300 mm at 40°C. ２ The hot melt pressure-sensitive adhesive composition according to claim 5, wherein the viscosity is 1 / second or more.

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