Adhesive sheet

Abstract

The pressure-sensitive adhesive sheet (1a) is provided with a pressure-sensitive adhesive layer (11). The adhesive layer (11) contains an elastomer and a tackifier. The elastomer contains 25% or more by mass of styrene. The tackifier has a softening point of 100 DEG C or more. The ratio RET of the content of the tackifier to the content of the elastomer in the adhesive layer (11) is 0.1-0.8. The adhesive sheet (1a) satisfies the condition that the tensile force (FA) [N / 20mm] > the adhesive force (FB) [N / 20mm]. The adhesive sheet (1a) has an adhesive force FC of 1.0 N / 20 mm or more. The adhesive force FB is a 90 DEG peel adhesive force [N / 20 mm] measured after the ambient temperature of a test piece produced from the adhesive sheet (1a) is maintained for 7 days at 100 DEG C in a state in which the test piece is attached to a test plate.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet. Background Art

[0002] Conventionally, there are known PSA sheets that are intended to be peeled off after being attached to an adherend.

[0003] For example, Patent Document 1 describes a pressure-sensitive adhesive tape that can be re-detached without residue or damage by stretching substantially on the adhesive surface. This pressure-sensitive adhesive tape comprises at least one adhesive layer formed by foaming microspheres and at least one carrier B. The pressure-sensitive adhesive A forming the adhesive layer comprises an elastomer portion (a1) based on at least one polyvinyl aromatic-polydiene block copolymer and a predetermined adhesive resin portion (a2). The pressure-sensitive adhesive A optionally includes a softening resin portion (a3).

[0004] Patent Document 2 describes an adhesive mounting assembly that can be attached or bonded to a surface and removed from the surface without damaging the surface. The adhesive mounting assembly comprises a backing, a first adhesive region, a second adhesive region, a non-adhesive region, and a mounting device. The first and second adhesive regions are regions on the first main flat surface of the backing. The non-adhesive region is, for example, positioned between the first and second adhesive regions. The mounting device is adjacent to the backing. The non-adhesive region is, for example, adjacent to the mounting device.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-138649

[0008] Patent Document 2: Japanese Patent Application No. 2019-534059 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] The techniques described in Patent Documents 1 and 2 do not contemplate the prolonged exposure of a PSA sheet to an adherend to a high temperature environment. Therefore, these techniques require further study from the perspective of peeling after prolonged exposure to a high temperature environment. Furthermore, the initial adhesive strength of a PSA sheet is also important for securing components.

[0011] Therefore, the present invention provides a PSA sheet that is advantageous in terms of having a predetermined adhesive strength to an adherend from the initial stage and being able to be peeled from the adherend after being exposed to a high-temperature environment for a long period of time.

[0012] Solutions for solving problems

[0013] The present invention provides an adhesive sheet, wherein the adhesive sheet comprises an adhesive layer comprising an elastomer and a tackifier, wherein the elastomer contains 25% or more of styrene by mass, the tackifier has a softening point of 100° C. or higher, the ratio of the content of the tackifier in the adhesive layer to the content of the elastomer by mass is 0.1 to 0.8, and the adhesive sheet satisfies a tensile force F A [N / 20mm]>Adhesion F B [N / 20mm], the tensile force F A The maximum test force F1 in the tensile test of the test piece prepared from the adhesive sheet, the cross-sectional area S1 [mm 2 ] and the thickness t of the adhesive sheet A [mm] expressed as F1·t A 20 / S1, the adhesive sheet has an adhesive force F of 1.0 N / 20 mm or more C The test piece in the tensile test is a rectangle with a width of 10 mm and a length of 40 mm when viewed from above. The distance between the chucks in the tensile test is 10 mm. The test speed in the tensile test is 1000 mm / min. The adhesive force F B The 90° peeling strength (N / 20 mm) is measured by attaching a test piece made of the adhesive sheet to a test plate, maintaining the test piece at an ambient temperature of 100°C for 7 days, and then peeling the test piece from the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022. C The 90° peel strength [N / 20 mm] is measured by peeling a test piece prepared from the PSA sheet from the test plate within 1 minute after the PSA sheet is attached to the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022.

[0014] Effects of the Invention

[0015] Such a pressure-sensitive adhesive sheet is advantageous in that it has a predetermined adhesive strength to an adherend from the initial stage and can be peeled from the adherend after being exposed to a high-temperature environment for a long period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a cross-sectional view schematically showing an example of the pressure-sensitive adhesive sheet of the present invention.

[0017] Figure 2 It is a cross-sectional view schematically showing an example of use of the pressure-sensitive adhesive sheet.

[0018] Figure 3 It is a cross-sectional view schematically showing another example of a PSA sheet. DETAILED DESCRIPTION

[0019] The embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0020] like Figure 1 As shown, the adhesive sheet 1a has an adhesive layer 11. The adhesive sheet 1a is, for example, a single-layer structure and only has an adhesive layer 11. The adhesive layer 11 contains an elastomer and a tackifier. The elastomer contains styrene in an amount of 25% or more by mass. The styrene content of the elastomer can be determined, for example, by carbon 13 nuclear magnetic resonance (C13 NMR) 13 The tackifier has a softening point of 100°C or higher. The softening point of the tackifier can be determined, for example, by the ring and ball method. The ratio R of the tackifier content in the adhesive layer 11 to the elastomer content is ET The tensile force F in the adhesive sheet 1a is 0.1 to 0.8. A [N / 20mm]>Adhesion F B [N / 20mm] condition. Tensile force F A The maximum test force F1 in the tensile test of the test piece made of the adhesive sheet 1a and the cross-sectional area S1 [mm 2 ] and the thickness t of the adhesive sheet 1a A [mm] expressed as F1·t A 20 / S1. The test piece in the tensile test is a rectangle with a width of 10 mm and a length of 40 mm when viewed from above. The distance between the chucks in the tensile test is 10 mm. The test speed in the tensile test is 1000 mm / min. The tensile test is conducted in accordance with Japanese Industrial Standard (JIS) K6251, except for parts otherwise specified. Adhesion F B The 90° peel strength (N / 20mm) is measured by attaching a test piece made from the adhesive sheet 1a to a test plate, maintaining the test piece at an ambient temperature of 100°C for 7 days, and then peeling the test piece from the test plate in accordance with JIS Z 0237:2022. Furthermore, the adhesive sheet 1a has an adhesive strength F of 1.0 N / 20 mm or greater. C Adhesion F C The 90° peel strength [N / 20 mm] is measured by peeling the PSA sheet 1a from the test plate within 1 minute after a test piece prepared from the PSA sheet 1a is attached to the test plate in accordance with JIS Z 0237:2022.

[0021] like Figure 2As shown, the adhesive sheet 1a can be used to provide the bonding structure 2. For example, the bonding structure 2 is obtained by pressing the adhesive sheet 1a between the adherend 3a and the adherend 3b. The bonding structure 2 can be exposed to a high temperature environment (for example, above 100°C) for a long time (for example, more than 168 hours). In addition, the adhesive sheet 1a can be peeled off from the adherend 3a and the adherend 3b after use of the bonding structure 2 and recycled. This helps promote the recycling of the adherend 3a and the adherend 3b, which is also ideal from the perspective of environmental protection.

[0022] According to the research of the present inventors, if the adherend joined by the adhesive sheet is exposed to a high temperature environment for a long time, the adhesive sheet is easily broken when the adhesive sheet is peeled off from the adherend, and it becomes complicated by peeling off the adhesive sheet. In addition, the adhesive of the adhesive sheet is easily left on the adherend, and it is also worried that the adhesive remaining on the adherend will hinder the recycling of the adherend. On the other hand, it is also important that the adhesive sheet plays a prescribed adhesive force in a state of being attached to the adherend for a long time or under a high temperature environment.

[0023] In the adhesive sheet 1a, the organic combination of the following features (a), (b) and (c) can exert the desired adhesive force on the adherend and can satisfy the tensile force F A > Adhesion F B As a result, when the adhesive sheet 1a is peeled from the adherend after being exposed to a high temperature environment for a long time, the adhesive sheet 1a is unlikely to break, and the adhesive and other components of the adhesive sheet 1a are unlikely to remain on the adherend. Therefore, the adhesive sheet 1a can be easily recycled.

[0024] (a) The elastomer contained in the adhesive layer 11 contains 25% by mass or more of styrene.

[0025] (b) The softening point of the tackifier contained in the adhesive layer 11 is 100° C. or higher.

[0026] (c) R ET It is 0.1 to 0.8.

[0027] In the adhesive sheet 1a, the adhesive force F C When the pressure-sensitive adhesive strength is 1.0 N / 20 mm or greater, the pressure-sensitive adhesive sheet 1 a can exhibit a predetermined pressure-sensitive adhesive strength immediately after being attached to an adherend.

[0028] The elastomer contained in the adhesive layer 11 contains 25% or more of styrene by mass, which tends to increase the tensile strength of the adhesive layer 11. Therefore, the adhesive sheet 1a is less likely to break when peeled from the adherend after prolonged exposure to high temperatures, making it easier to recover the adhesive sheet 1a.

[0029] The styrene content of the elastomer contained in the adhesive layer 11 may be 30% or more, 35% or more, or 40% or more by mass, and may be 70% or less, 60% or less, or 50% or less, for example.

[0030] The softening point of the tackifier contained in adhesive layer 11 is 100°C or higher. This prevents the adhesive strength of adhesive layer 11 from being excessively high relative to the tensile strength of adhesive sheet 1a, even when adhesive sheet 1a is bonded to an adherend and exposed to a high-temperature environment for a long period of time. Consequently, when adhesive sheet 1a is peeled from an adherend after prolonged exposure to a high-temperature environment, the adhesive and other components of the adhesive sheet 1a are less likely to remain on the adherend.

[0031] The softening point of the binder-imparting agent may be 105° C. or higher, or 110° C. or higher. The softening point of the binder-imparting agent may be, for example, 160° C. or lower, 150° C. or lower, or 140° or lower.

[0032] R ET When the ratio R is 0.1 or more, the adhesive sheet 1a can easily have the desired adhesive force to the adherend. ET By setting the ratio to 0.8 or less, even when the adhesive sheet 1a is exposed to a high temperature environment for a long time while bonded to an adherend, the adhesive strength of the adhesive layer 11 is easily prevented from being excessively high. Therefore, when the adhesive sheet 1a is peeled from the adherend after being exposed to a high temperature environment for a long time, the adhesive and the like of the adhesive sheet 1a are less likely to remain on the adherend.

[0033] R ET It can be 0.15 or more, 0.2 or more, or 0.25 or more. ET It can be 0.75 or less, or 0.7 or less. ET It may fall within a range defined by a lower limit value selected from the group consisting of 0.1, 0.15, 0.2, and 0.25 and an upper limit value selected from the group consisting of 0.8, 0.75, and 0.7.

[0034] Tensile force F A As long as the tensile force F A > Adhesion F B The conditions are not limited to specific values. A For example, it is 10 [N / 20 mm] or more. This makes it more difficult for the pressure-sensitive adhesive sheet 1a to break when it is peeled from an adherend after being exposed to a high-temperature environment for a long period of time.

[0035] Tensile force F AIt can be 15 [N / 20mm] or more, 20 [N / 20mm] or more, 25 [N / 20mm] or more, 30 [N / 20mm] or more, 35 [N / 20mm] or more, or 40 [N / 20mm] or more. A For example, it may be 100 [N / 20 mm] or less, may be 90 [N / 20 mm] or less, or may be 80 [N / 20 mm] or less.

[0036] Adhesion F B As long as the tensile force F A > Adhesion F B The conditions are not limited to specific values. B For example, it may be 5 [N / 20mm] or more, 10 [N / 20mm] or more, 15 [N / 20mm] or more, 20 [N / 20mm] or more, or 25 [N / 20mm] or more. B For example, it may be 80 [N / 20 mm] or less, may be 75 [N / 20 mm] or less, or may be 70 [N / 20 mm] or less.

[0037] Adhesion F C It may be 2 [N / 20mm] or more, 5 [N / 20mm] or more, or 10 [N / 20mm] or more. C For example, it may be 80 [N / 20 mm] or less, may be 70 [N / 20 mm] or less, or may be 60 [N / 20 mm] or less.

[0038] In the adhesive layer 11, the difference D obtained by subtracting the SP value of the tackifier from the SP value of the elastomer is not limited to a specific value. In the adhesive layer 11, for example, -5.0 MPa is satisfied. 0.5 ≤D≤1.5MPa 0.5 conditions. As a result, in the adhesive layer 11, the elastomer and the tackifier are easily compatible, and the adhesive sheet 1a is more likely to have the desired adhesion to the adherend. The SP value is Hildebrand's SP value. For example, the calculation software Hansen Solubility Parameters in Practice (HSPiP) can be used to infer the SP value of the elastomer and the SP value of the tackifier. In the calculation using HSPiP, the molecular structure recorded in the SMILES (Simplified Molecular Input Line Entry Specification) notation is input. In addition, for example, the calculation of the SP values of the elastomer and the tackifier is based on the composition of structural units such as styrene.

[0039] The SP value of the elastic body is, for example, 15 to 20 MPa. 0.5 , can also be 16 ~ 20MPa 0.5 , can also be 17 ~ 19MPa 0.5 .

[0040] The SP value of the thickener is, for example, 17 to 21 MPa. 0.5 , can also be 18 ~ 21MPa 0.5 .

[0041] In the adhesive layer 11, D may be -4.5 MPa 0.5 Above, can also be -4.0MPa 0.5 Above, can also be -3.5MPa 0.5 Above, can also be -3.0MPa 0.5 Above, can also be -2.5MPa 0.5 Above, can also be -2.0MPa 0.5 Above. D can be 1.5MPa 0.5 Below, can also be 1.0MPa 0.5 Below, can also be 0.5MPa 0.5 Below, 0MPa is also possible 0.5 Below, can also be -0.5MPa 0.5 Below, can also be -1.0MPa 0.5 the following.

[0042] The tensile strength of the elastic body contained in the adhesive layer 11 is not limited to a specific value. For example, the tensile strength is 10 MPa or more. A It is easy to grow larger, and the pressure-sensitive adhesive sheet 1a is less likely to break when peeled from an adherend after being exposed to a high-temperature environment for a long time.

[0043] The tensile strength of the elastomer may be 15 MPa or more, or 20 MPa or more. The tensile strength of the elastomer contained in the adhesive layer 11 may be, for example, 50 MPa or less, 45 MPa or less, or 40 MPa or less.

[0044] The elastomer contained in the adhesive layer 11 is, for example, a styrene block copolymer. Examples of the styrene block copolymer include styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butadiene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-isobutylene-styrene block copolymer, and styrene-isoprene-propylene-styrene block copolymer.

[0045] The tackifier is not limited to a specific substance as long as it has a softening point of 100°C or above. The tackifier is, for example, a specified resin. Examples of such resins include rosin-based tackifier resins, terpene-based tackifier resins, hydrocarbon-based tackifier resins, phenol-based tackifier resins, ketone-based tackifier resins, polyamide-based tackifier resins, epoxy-based tackifier resins, and elastic-based tackifier resins. Examples of rosin-based tackifier resins include unmodified rosin, modified rosin, rosin phenol-based resins, and rosin ester-based resins. Examples of terpene-based tackifier resins include terpene-based resins, terpene-phenol-based resins, styrene-modified terpene-based resins, aromatic-modified terpene-based resins, and hydrogenated terpene-based resins. Examples of hydrocarbon-based tackifier resins include aliphatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic / aromatic petroleum resins, aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone-based resins, and coumarone-indene-based resins. Examples of aromatic hydrocarbon resins include styrene resins and xylene resins. Examples of phenolic tackifying resins include alkylphenol resins, xylene formaldehyde resins, resol resins, and novolak resins. The tackifier is preferably an alicyclic hydrocarbon or aromatic hydrocarbon resin.

[0046] The thickness of the adhesive layer 11 is not limited to a specific value. The adhesive layer 11 has a thickness of, for example, 30 to 500 μm. The thickness of the adhesive layer 11 may be 50 μm or more, or 75 μm or more. The thickness of the adhesive layer 11 may be 400 μm or less, or 350 μm or less.

[0047] The adhesive layer 11 may contain a filler. This facilitates adjusting the viscosity of the adhesive layer 11 to a desired range. The filler material is not limited to a specific material. Fillers include, for example, inorganic substances. Examples of inorganic substances include calcium carbonate, magnesium carbonate, clay, talc, mica, bentonite, silica, alumina, aluminum silicate, and aluminum. The adhesive layer 11 may also contain no filler.

[0048] The filler content in the adhesive layer 11 is not limited to a specific value. The ratio of the filler content in the adhesive layer 11 to the elastomer content, measured on a mass basis, is, for example, 0.05 or greater, 0.1 or greater, or 0.2 or greater. The ratio of the filler content in the adhesive layer 11 to the elastomer content is, for example, 3 or less, 2.5 or less, 2 or less, 1.5 or less, 1 or less, or 0.5 or less.

[0049] From various viewpoints, the adhesive sheet 1a can be modified. For example, the adhesive sheet 1a can be Figure 3The adhesive sheet 1b is constructed as shown. With respect to the adhesive sheet 1b, except for the parts specifically described, it is constructed in the same manner as the adhesive sheet 1a. The components of the adhesive sheet 1b that are identical or corresponding to the components of the adhesive sheet 1a are marked with the same reference numerals, and detailed descriptions are omitted. The descriptions related to the adhesive sheet 1a also apply to the adhesive sheet 1b as long as they are not technically inconsistent.

[0050] like Figure 3 As shown, the adhesive sheet 1b includes a foam substrate 12, and the adhesive layer 11 is disposed on the substrate 12. With this configuration, the foam substrate 12 easily deforms to match the adherends, and even when the distance between the adherends is large, the adhesive sheet 1b easily fills the gap between the adherends.

[0051] The adhesive sheet 1b, for example, includes a pair of adhesive layers 11, with a substrate 12 disposed between the adhesive layers 11. The pair of adhesive layers 11 form a first surface 11a and a second surface 11b, which serve as both end surfaces in the thickness direction of the adhesive sheet 1b. The adhesive sheet 1b can be modified to include a single adhesive layer in contact with one main surface of the substrate 12.

[0052] The substrate 12 may have, for example, a closed-cell structure, an open-cell structure, or a semi-closed-cell and semi-open-cell structure. In the case of a semi-closed-cell and semi-open-cell structure, the substrate 12 includes open cells before compression deformation. For example, when the substrate 12 is compressed to produce a compressive strain of 50% or more, the open cells become clogged, thereby transforming the structure into a closed-cell structure.

[0053] The material forming the substrate 12 is not limited to a specific material. The substrate 12 may be, for example, a rubber foam, a polyurethane foam, a silicone foam, or an acrylic foam.

[0054] When the substrate 12 is a rubber foam, the rubber can be an olefin elastomer, a styrene elastomer, a butyl elastomer, a vinyl chloride elastomer, or a natural rubber. Examples of olefin elastomers are ethylene-propylene rubber (EPM) and ethylene-propylene-diene rubber (EPDM). Styrene elastomers include styrene-butadiene rubber (SBR), styrene-butadiene-styrene rubber (SBS), styrene-isoprene-styrene rubber (SIS), styrene-ethylene-butadiene rubber, styrene-ethylene-butylene-styrene rubber (SEBS), styrene-isobutylene-styrene block rubber (SIBS), and styrene-isoprene-propylene-styrene rubber. Examples of butyl elastomers include butyl rubber, polyisobutylene rubber, polybutene, polyisoprene rubber, and nitrile rubber (NBR). Examples of vinyl chloride elastomers include chloroprene rubber and chlorosulfonated polyethylene rubber.

[0055] The thickness of the substrate 12 is not limited to a specific value and may be, for example, 0.5 to 40 mm, 1 to 40 mm, 1 to 30 mm, 1 to 20 mm, or 2 to 20 mm.

[0056] Example

[0057] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[0058] <Example 1>

[0059] Kraton's SBS resin D1155 and Arakawa Chemical Industries' tackifier ARKON M-115 were kneaded at a ratio of 100 parts by mass and 35 parts by mass, respectively, to form a mixture. This mixture was hot-pressed at 150°C and 4 MPa to produce the 100 μm-thick PSA sheet of Example 1. The styrene content of SBS resin D1155 was 40% by mass. The softening point of ARKON M-115 was 115°C according to the ring and ball method.

[0060] <Example 2 and Example 3>

[0061] PSA sheets of Example 2 and Example 3 were obtained in the same manner as in Example 1 except that the amount of the tackifier added was changed to 10 parts by mass and 50 parts by mass, respectively.

[0062] <Example 4>

[0063] A PSA sheet of Example 4 was obtained in the same manner as in Example 1, except that SBS resin TUFPRENE A manufactured by Asahi Kasei Corporation was used instead of SBS resin D1155. TUFPRENE is a registered trademark. The thickness of the PSA sheet of Example 4 was 300 μm. The styrene content of TUFPRENE A was 40% by mass.

[0064] <Example 5>

[0065] A PSA sheet of Example 5 was obtained in the same manner as in Example 1 except that SBS resin TR-2003 manufactured by ENEOS Materials was used instead of SBS resin D1155. The thickness of the PSA sheet of Example 5 was 100 μm. The styrene content of TR-2003 was 43% by mass.

[0066] <Example 6>

[0067] SBS resin TR-2003 manufactured by ENSOS Materials, tackifier ARKON M-115 manufactured by Arakawa Chemical Industries, Ltd., and ground calcium carbonate (filler) manufactured by MARUO CALCIUM were kneaded at a ratio of 100 parts by mass, 40 parts by mass, and 35 parts by mass, respectively, to form a mixture. This mixture was hot-pressed at 150°C and 4 MPa to produce a 100 μm thick adhesive sheet of Example 6.

[0068] <Example 7>

[0069] A PSA sheet was obtained in the same manner as in Example 1. A laminate was obtained by attaching the PSA sheet to one main surface of Nitto Denko Corporation's foam EE-1000. The foam EE-1000 was an EPDM foam with an open-cell structure. The thickness of the foam EE-1000 was 5 mm. A pressure of 2 kPa was applied to the laminate in an oven maintained at 140°C for 5 minutes to bond the PSA sheet to the foam. This yielded the PSA sheet of Example 7.

[0070] <Example 8>

[0071] A pressure-sensitive adhesive sheet of Example 8 was obtained in the same manner as in Example 7 except that SUPER SHEET H, a polyurethane foam manufactured by Nippon Hakujyo Co., Ltd., was used instead of the foam EE-1000.

[0072] <Example 9>

[0073] A pressure-sensitive adhesive sheet of Example 9 was obtained in the same manner as in Example 7 except that TE800H, a silicone foam manufactured by Zhejiang Tianyi Materials Co., Ltd., was used instead of the foam EE-1000.

[0074] <Example 10>

[0075] A pressure-sensitive adhesive sheet of Example 10 was obtained in the same manner as in Example 7 except that HYPERJOINT H7012, an acrylic foam tape manufactured by Nitto Denko Corporation, was used instead of the foam EE-1000. HYPERJOINT is a registered trademark.

[0076] <Example 11>

[0077] A PSA sheet of Example 11 was obtained in the same manner as in Example 1 except that the amount of the tackifier was changed to 70 parts by mass and the thickness of the PSA sheet was adjusted to 300 μm.

[0078] <Comparative Examples 1 and 2>

[0079] PSA sheets of Comparative Example 1 and Comparative Example 2 were obtained in the same manner as in Example 1 except that the amount of the tackifier was changed to 5 parts by mass and 70 parts by mass, respectively.

[0080] Comparative Example 3

[0081] A PSA sheet of Comparative Example 3 was obtained in the same manner as in Example 1, except that SBS resin D0243 manufactured by Kraton Corporation was used instead of SBS resin D1155. The styrene content in SBS resin D0243 was 24% by mass.

[0082] Comparative Example 4

[0083] A PSA sheet of Comparative Example 4 was obtained in the same manner as in Example 1, except that tackifier T-REZ RB100 manufactured by ENEOS was used instead of tackifier ARKON M-115. The softening point of T-REZ RB100 was 100° C. according to the ring and ball method.

[0084] <Comparative Example 5>

[0085] A PSA sheet of Comparative Example 5 was obtained in the same manner as in Example 1, except that tackifier PENSEL C manufactured by Arakawa Chemical Industries, Ltd. was used instead of tackifier ARKON M-115. The softening point of PENSEL C was 120° C. according to the ring and ball method.

[0086] <Comparative Example 6>

[0087] A PSA sheet of Comparative Example 6 was obtained in the same manner as in Example 1, except that tackifier ARKON M90 manufactured by Arakawa Chemical Industries, Ltd. was used instead of tackifier ARKON M-115. The softening point of ARKON M90 was 90° C. according to the ring and ball method.

[0088] <Comparative Example 7>

[0089] A PSA sheet of Comparative Example 7 was obtained in the same manner as in Example 1, except that SIS resin Quintac 3433N manufactured by ZEON Corporation was used instead of SBS resin D1155. The styrene content in Quintac 3433N was 15% by mass. Quintac is a registered trademark.

[0090] <Comparative Example 8>

[0091] A PSA sheet of Comparative Example 8 was obtained in the same manner as in Example 1 except that the amount of the tackifier added was changed to 100 parts by mass.

[0092] (SP value)

[0093] The Hildebrand SP values of the SBS resin, SIS resin, and tackifier used in each Example and Comparative Example were calculated using the calculation software HSPiP. The molecular structures were input using SMILES notation, and the calculation was performed taking into account the composition of each structural unit in the SBS and SIS resins. Furthermore, the difference D, obtained by subtracting the SP value of the tackifier from the SP value of the SBS or SIS resin, was calculated. The results are shown in Tables 1 and 2.

[0094] (Tensile test)

[0095] A tensile test was performed using a test piece made of the adhesive sheet of each embodiment and each comparative example and the SBS resin and SIS resin used in each embodiment or each comparative example. The test piece is a rectangle with a width of 10 mm and a length of 40 mm when viewed from above. The tensile test was performed under the conditions of room temperature, a test speed of 1000 mm / min and a distance between the chucks of 10 mm. Other conditions of the tensile test were determined in accordance with JIS K6251. The tensile strength [MPa] and the tensile force F were calculated according to the following formulas (1) and (2): A The results are shown in Tables 1 and 2.

[0096] Tensile strength [MPa] = maximum test force [N] / cross-sectional area of test piece [mm 2 Formula (1)

[0097] Tensile force F A [N / 20mm] = 20mm × thickness of test piece [mm] × maximum test force [N] / cross-sectional area of test piece [mm 2 Formula (2)

[0098] (90° peel adhesion strength measurement)

[0099] Test pieces were made using the adhesive sheets of each embodiment and each comparative example. The test piece was a rectangle with a length of 100 mm and a width of 20 mm when viewed from above. A 50 μm polyethylene terephthalate (PET) film was adhered to one main surface of the test piece as a substrate. The foam or foam of the adhesive sheets of Examples 7 to 10 was adhered to the PET film for the substrate using an acrylic double-sided tape No. 5000NS manufactured by Nitto Denko Corporation. The test piece was placed on a test plate made of SUS304 with a thickness of 1.5 mm, and a 2 kg roller was moved back and forth once on the test piece to adhere it. After the test piece was attached to the test plate, no load was applied to the test piece, and it was peeled off within 1 minute from the attachment, and the initial 90° peeling adhesion F was measured in accordance with JIS Z 0237:2022. C The peeling speed was adjusted to 300 mm / min. The results are shown in Tables 1 and 2.

[0100] In addition to the following aspects, the initial 90° peel adhesion F C The peel strength after the durability test was similarly measured. After the test piece was attached to the test plate, no load was applied to the test piece and the test piece and the test plate were stored in an oven maintained at 100°C for 7 days. The test piece was then removed from the oven and allowed to cool naturally at room temperature for 1 hour. The 90° peel strength F was then measured according to JIS Z 0237:2022. B The results are shown in Tables 1 and 2.

[0101] (Evaluation of Recyclability of PSA Sheet)

[0102] The adhesive sheets of each embodiment and each comparative example were placed on a plate having a thickness of 1.5 mm made of SUS304, and a 2 kg roller was moved back and forth once on the adhesive sheet to attach the adhesive sheet to the plate. The test piece was stored together with the test plate in an oven maintained at 100 ° C for 7 days. Then, the test piece was taken out of the oven, cooled naturally at room temperature for 1 hour, and then the end of the adhesive sheet was grasped by hand and peeled off from the plate at a speed of about 300 mm / min. In this case, the recyclability of the adhesive sheet was evaluated according to the following benchmark. The results are shown in Table 1.

[0103] Good: The adhesive sheet is not broken, and no adhesive residue from the adhesive sheet remains on the plate.

[0104] Disadvantages: The adhesive sheet was broken and / or adhesive residue from the adhesive sheet was observed on the plate.

[0105] As shown in Tables 1 and 2, the adhesive sheets of the examples have the following characteristics (a), (b), and (c). In the examples, the tensile force F A > Adhesion F BIn addition, it was confirmed that the recyclability of the adhesive sheet of the embodiment was better than that of Comparative Examples 2, 3, 6, and 7. Therefore, it was shown that the adhesive sheet of the embodiment was easy to be recycled by peeling even if it was exposed to a high temperature environment for a long time after being attached to the adherend. In addition, the initial 90° peeling adhesion F of the adhesive sheet of each embodiment was C The initial adhesive force of the adhesive sheets of each embodiment is higher than that of the adhesive sheets of Comparative Examples 1, 4, and 5, indicating that the adhesive sheets of each embodiment have good adhesive force from the beginning. According to the embodiment, it is shown that the specified adhesive force can be exerted from the beginning and the tensile force F can be achieved. A > Adhesion F B conditions.

[0106] (a) The elastomer (SBS resin) contains 25% by mass or more of styrene.

[0107] (b) The softening point of the tackifier is 100°C or higher.

[0108] (c) Ratio of the mass of the tackifier to the mass of the elastomer ET It is 0.1 to 0.8.

[0109] On the other hand, in Comparative Example 1, the ET The initial 90° peel adhesion F is 0.05. C In Comparative Example 2, the ET is 0.7, which does not meet the tensile force F A > Adhesion F B In Comparative Example 3, the styrene content in the SBS resin is 24% by mass, which does not meet the tensile strength F A > Adhesion F B In Comparative Examples 4 and 5, the initial 90° peel adhesion F C This indicates that in order for the adhesive sheet to exhibit the desired adhesiveness, the difference D in the SP value should be within a specified range (e.g., -5.0 MPa). 0.5 Above and 1.5MPa 0.5 In Comparative Example 6, the softening point of the thickener is 90°C, which does not satisfy the tensile force F A > Adhesion F B In Comparative Example 7, the styrene content in the SIS resin is 15% by mass, which does not satisfy the tensile force F A > Adhesion F B conditions.

[0110] A first embodiment of the present invention provides a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer comprising an elastomer and a tackifier, wherein the elastomer contains 25% or more of styrene by mass, the tackifier has a softening point of 100° C. or higher, the ratio of the content of the tackifier in the pressure-sensitive adhesive layer to the content of the elastomer by mass is 0.1 to 0.8, and the pressure-sensitive adhesive sheet satisfies a tensile force F A [N / 20mm]>Adhesion F B [N / 20mm], the tensile force F A The maximum test force F1 in the tensile test of the test piece prepared from the adhesive sheet, the cross-sectional area S1 [mm 2 ] and the thickness t of the adhesive sheet A [mm] expressed as F1·t A 20 / S1, the adhesive sheet has an adhesive force F of 1.0 N / 20 mm or more C The test piece in the tensile test is a rectangle with a width of 10 mm and a length of 40 mm when viewed from above. The distance between the chucks in the tensile test is 10 mm. The test speed in the tensile test is 1000 mm / min. The adhesive force F B The 90° peeling strength (N / 20 mm) is measured by attaching a test piece made of the adhesive sheet to a test plate, maintaining the test piece at an ambient temperature of 100°C for 7 days, and then peeling the test piece from the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022. C The 90° peel strength [N / 20 mm] is measured by peeling a test piece prepared from the PSA sheet from the test plate within 1 minute after the PSA sheet is attached to the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022.

[0111] A second aspect of the present invention provides the PSA sheet of the first aspect, wherein D, which is the difference between the SP value of the elastomer and the SP value of the tackifier, satisfies -5.0 MPa. 0.5 ≤D≤1.5MPa 0.5 conditions.

[0112] A third aspect of the present invention provides the PSA sheet according to the first or second aspect, wherein the elastomer has a tensile strength of 10 MPa or greater.

[0113] A fourth aspect of the present invention provides the PSA sheet according to any one of the first to third aspects, wherein the tensile force F A It is 10N / 20mm or more.

[0114] There is provided the PSA sheet according to any one of the first to fourth aspects.

[0115] A fifth aspect of the present invention provides the PSA sheet according to any one of the first to fourth aspects, further comprising a substrate which is a foam, wherein the PSA layer is disposed on the substrate.

[0116] [Table 1]

[0117]

[0118] [Table 2]

[0119]

Claims

1. An adhesive sheet, wherein: The pressure-sensitive adhesive sheet comprises a pressure-sensitive adhesive layer comprising an elastomer and a tackifier, wherein the elastomer contains 25% by mass or more of styrene, and the tackifier has a softening point of 100° C. or more. The ratio of the content of the tackifier in the adhesive layer to the content of the elastomer is 0.1 to 0.8 on a mass basis. The adhesive sheet satisfies the tensile force F A > Adhesion F B The tensile force F A and the adhesive force F B The unit is N / 20mm, The tensile force F A The maximum test force F1 in the tensile test of the test piece made of the adhesive sheet, the cross-sectional area S1 of the test piece, and the thickness t of the adhesive sheet are used. A Expressed as F1·t A 20 / S1, the unit of the cross-sectional area S1 of the test piece is mm 2 , the thickness of the adhesive sheet is t A The unit is mm, The adhesive sheet has an adhesive force F of 1.0 N / 20 mm or more. C , The test piece in the tensile test is a rectangle having a width of 10 mm and a length of 40 mm when viewed from above. The distance between the chucks in the tensile test was 10 mm. The test speed in the tensile test was 1000 mm / min. The adhesive force F B The 90° peel strength is measured by attaching a test piece made from the adhesive sheet to a test plate, maintaining the test piece at an ambient temperature of 100°C for 7 days, and then peeling the test piece from the test plate in accordance with Japanese Industrial Standard JIS Z 0237:2022. The unit of the 90° peel strength is N / 20mm. The adhesive force F C The 90° peel strength is measured by peeling a test piece made from the PSA sheet from a test plate within 1 minute after the sheet is attached to the test plate in accordance with JIS Z 0237:2022. The unit of the 90° peel strength is N / 20 mm.

2. The adhesive sheet according to claim 1, wherein The difference D obtained by subtracting the SP value of the tackifier from the SP value of the elastomer satisfies -5.0 MPa. 0.5 ≤D≤1.5MPa 0.5 conditions.

3. The adhesive sheet according to claim 1, wherein The elastomer has a tensile strength of 10 MPa or more.

4. The adhesive sheet according to claim 1, wherein The tensile force F A It is 10N / 20mm or more.

5. The adhesive sheet according to claim 1, wherein The pressure-sensitive adhesive sheet further comprises a foam substrate. The adhesive layer is disposed on the substrate.

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