Adhesive sheet

Abstract

To provide a pressure sensitive adhesive sheet advantageous from the viewpoint of being peeled from an adherend after being exposed to high temperature environment for a long term.SOLUTION: A pressure sensitive adhesive sheet 1a includes an adhesive layer 11 including an elastomer including styrene of 25% or more by mass and a tackifier having a softening point of 100°C or more. The ratio RET of the content of the tackifier to that of the elastomer in the adhesive layer 11 is 0.1-0.8; the pressure sensitive adhesive sheet 1a satisfies the condition of a tensile force FA [N / 20 mm]>an adhesive power FB [N / 20 mm] and has an adhesive power FC of 1.0 N / 20 mm or more; and the adhesive power FB is a 90° peeling adhesive power [N / 20 mm] measured after keeping the environmental temperature of the specimen at 100°C for 7 days in the state of bonding a specimen prepared from the pressure sensitive adhesive sheet 1a to a test plate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an adhesive sheet. [Background technology]

[0002] Conventionally, adhesive sheets are known that are intended to be peeled off after being attached to a substrate.

[0003] For example, Patent Document 1 describes a pressure-sensitive adhesive strip that can be reattached without residue or damage by tensile stretching at a substantially adhesive surface. This pressure-sensitive adhesive strip comprises at least one adhesive layer foamed with microballoons 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 comprises a softening resin portion (a3).

[0004] Patent Document 2 describes an adhesive mounting assembly that can adhere to or bond to a surface and can be peeled off from the surface without damaging it. This 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 located, for example, between the first and second adhesive regions. The mounting device is adjacent to the backing. The non-adhesive region is adjacent to the mounting device, for example. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-138649 [Patent Document 2] Special Publication No. 2019-534059 [Overview of the project] [Problems that the invention aims to solve]

[0006] The technologies described in Patent Documents 1 and 2 do not assume that the adhesive sheet attached to the substrate will be exposed to a high-temperature environment for a long period of time. Therefore, these technologies deserve reconsideration from the perspective of peeling off after prolonged exposure to a high-temperature environment. In addition, the initial adhesive strength of the adhesive sheet is also important for fixing the components.

[0007] Therefore, the present invention provides an adhesive sheet that is advantageous in that it has a predetermined adhesive strength to the adherend from the beginning and can be peeled off the adherend after being exposed to a high-temperature environment for a long period of time. [Means for solving the problem]

[0008] The present invention It is an adhesive sheet, The adhesive layer comprises an elastomer containing 25% or more styrene by mass and a tackifier having a softening point of 100°C or higher. The ratio of the content of the tackifier to the content of the elastomer in the adhesive layer is 0.1 to 0.8 by mass. The aforementioned adhesive sheet is subjected to a tensile force F A [N / 20mm]>Adhesive force F B The condition [N / 20mm] is met, The aforementioned tensile force F A F1 is the maximum test force F1 in a tensile test performed on a test specimen made from the adhesive sheet, and S1 is the cross-sectional area S1 [mm²] of the test specimen. 2 ], and the thickness t of the adhesive sheet A [mm] F1·t A • Expressed as 20 / S1, The aforementioned adhesive sheet has an adhesive strength F of 1.0 N / 20 mm or more. C It has, The test specimen in the tensile test is rectangular in shape, having a width of 10 mm and a length of 40 mm in plan view. The distance between the chucks in the aforementioned tensile test was 10 mm. The test speed in the tensile test is 1000 mm / min, the adhesive force F B is the 90° peel adhesive force [N / 20 mm] measured by peeling the test piece from the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022 after maintaining the environmental temperature of the test piece at 100 °C for 7 days in a state where the test piece made from the adhesive sheet is attached to the test plate, the adhesive force F C is the 90° peel adhesive force [N / 20 mm] measured by peeling the adhesive sheet from the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022 within 1 minute after attaching the test piece made from the adhesive sheet to the test plate, An adhesive sheet is provided.

Advantages of the Invention

[0009] The above adhesive sheet is advantageous from the viewpoints of having a predetermined adhesive force to the adherend from the initial stage and peeling from the adherend after being exposed to a high-temperature environment for a long period.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of the adhesive sheet according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing an example of the use of the adhesive sheet. [Figure 3] FIG. 3 is a cross-sectional view schematically showing another example of the adhesive sheet.

Modes for Carrying Out the Invention

[0011] Embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

[0012] As shown in Figure 1, the adhesive sheet 1a comprises an adhesive layer 11. The adhesive sheet 1a is, for example, a single-layer structure and comprises only the adhesive layer 11. The adhesive layer 11 contains an elastomer and a tackifier. The elastomer contains 25% or more styrene by mass. The styrene content in the elastomer is, for example, determined by carbon-13 nuclear magnetic resonance ( 13 The softening point of the tackifier can be determined by structural analysis of the elastomer based on ¹¹¹NMR. 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-sphere method. The ratio of the tackifier content to the elastomer content in the tackifier layer 11 is R. ET The value is 0.1 to 0.8. In adhesive sheet 1a, the tensile force F A [N / 20mm]>Adhesive force F B The condition [N / 20mm] is met. Tensile force F A F1 is the maximum test force F1 in a tensile test performed on a test specimen made from adhesive sheet 1a, and S1 is the cross-sectional area of ​​the test specimen [mm²]. 2 ], and the thickness t of the adhesive sheet 1a A [mm] F1·t A This is expressed as ·20 / S1. The specimen used in this tensile test is rectangular in shape, with a width of 10 mm and a length of 40 mm in plan view. 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 performed in accordance with, for example, Japanese Industrial Standard (JIS) K6251, except where specifically described. Adhesion strength F B This refers to the 90° peel adhesion strength [N / 20mm] measured by peeling a test specimen made from adhesive sheet 1a from the test plate in accordance with JIS Z 0237:2022 after maintaining the ambient temperature of the test specimen at 100°C for 7 days. In addition, adhesive sheet 1a has an adhesion strength F of 1.0 N / 20mm or higher. C It has adhesive strength F. C This is the 90° peel adhesion strength [N / 20mm] measured by peeling the adhesive sheet 1a from the test plate within 1 minute after attaching a test piece made from adhesive sheet 1a to the test plate, in accordance with JIS Z 0237:2022.

[0013] As shown in Figure 2, a bonding structure 2 can be provided using an adhesive sheet 1a. For example, the bonding structure 2 is obtained by pressing the adhesive sheet 1a between adherends 3a and 3b. The bonding structure 2 can be exposed to high temperatures (e.g., 100°C or higher) for a long period of time (e.g., 168 hours or more). In addition, the adhesive sheet 1a can be peeled off from adherends 3a and 3b and recovered after use of the bonding structure 2. This promotes the recycling of adherends 3a and 3b, which is desirable from an environmental protection standpoint.

[0014] According to our research, when an object bonded with an adhesive sheet is exposed to a high-temperature environment for a long period of time, the adhesive sheet is prone to tearing when peeled off the object, making the recovery process by peeling off the adhesive sheet cumbersome. In addition, adhesive residue from the adhesive sheet tends to remain on the object, and there are concerns that this residue may hinder the recycling of the object. On the other hand, it is also important that the adhesive sheet maintains its predetermined adhesive strength for a long period of time or in a high-temperature environment while attached to the object.

[0015] In the adhesive sheet 1a, the desired adhesive force to the adherend is exhibited by the organic bonding of the following features (a), (b), and (c), and the tensile force F A >Adhesive force F B The following conditions may be met. As a result, the adhesive sheet 1a is less likely to break when peeled off the adherend after being exposed to a high-temperature environment for a long period of time, and less of the adhesive from the adhesive sheet 1a remains on the adherend. Therefore, the adhesive sheet 1a is easy to recover. (a) The elastomer contained in the adhesive layer 11 contains 25% or more styrene by mass. (b) The softening point of the tackifier contained in the adhesive layer 11 is 100°C or higher. (c) Ratio R ET The values ​​are between 0.1 and 0.8.

[0016] In addition, in the adhesive sheet 1a, the adhesive strength F CBecause the adhesive strength is 1.0 N / 20 mm or more, the adhesive sheet 1a can exhibit a predetermined adhesive strength immediately after being attached to the substrate.

[0017] The elastomer contained in the adhesive layer 11 contains 25% or more 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 off from the adherend after being exposed to a high-temperature environment for a long period of time, and the adhesive sheet 1a is easier to recover.

[0018] The styrene content in the elastomer contained in the adhesive layer 11 may be 30% or more, 35% or more, or 40% or more by mass. The styrene content may be, for example, 70% or less, 60% or less, or 50% or less.

[0019] Because the tackifier contained in the adhesive layer 11 has a softening point of 100°C or higher, even if the adhesive sheet 1a is exposed to a high-temperature environment for a long period of time while bonded to a substrate, it is easy to avoid the adhesive force of the adhesive layer 11 becoming too high relative to the tensile strength of the adhesive sheet 1a. For this reason, when peeling the adhesive sheet 1a from the substrate after being exposed to a high-temperature environment for a long period of time, the adhesive and other components of the adhesive sheet 1a are less likely to remain on the substrate.

[0020] The softening point of the tackifier may be 105°C or higher, or 110°C or higher. The softening point of the tackifier may be, for example, 160°C or lower, or 150°C or lower, or 140°C or lower.

[0021] ratio R ET When R is 0.1 or higher, the adhesive sheet 1a is more likely to have the desired adhesive strength to the adherend. In addition, R ET Because the ratio is 0.8 or less, even if the adhesive sheet 1a is exposed to a high-temperature environment for a long period of time while bonded to the adherend, it is easy to avoid the adhesive strength of the adhesive layer 11 becoming too high. For this reason, when peeling the adhesive sheet 1a from the adherend after being exposed to a high-temperature environment for a long period of time, the adhesive and other materials of the adhesive sheet 1a are less likely to remain on the adherend.

[0022] ratio R ET The ratio R may be 0.15 or greater, 0.2 or greater, or 0.25 or greater. ET The ratio R may be 0.75 or less, or 0.7 or less. ET It may fall within a range determined by a lower limit, which is one value selected from the group consisting of 0.1, 0.15, 0.2, and 0.25, and an upper limit, which is one value selected from the group consisting of 0.8, 0.75, and 0.7.

[0023] Tensile force F A is a tensile force F A >Adhesive force F B As long as the conditions are met, it is not limited to a specific value. Tensile force F A For example, it is 10 [N / 20mm] or more. This makes the adhesive sheet 1a less likely to break when peeled off from the adherend after being exposed to a high-temperature environment for a long period of time.

[0024] Tensile force F A Tensile force F may 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 / 20mm] or less, 90 [N / 20mm] or less, or 80 [N / 20mm] or less.

[0025] Adhesive force F B is a tensile force F A >Adhesive force F B As long as the conditions are met, it is not limited to a specific value. Adhesion F 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. Adhesion strength F BFor example, it may be 80 [N / 20mm] or less, 75 [N / 20mm] or less, or 70 [N / 20mm] or less.

[0026] Adhesive force F C The adhesive strength F may be 2N / 20mm or more, 5N / 20mm or more, or 10N / 20mm or more. C For example, it may be 80 [N / 20mm] or less, 70 [N / 20mm] or less, or 60 [N / 20mm] or less.

[0027] 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. For example, in the adhesive layer 11, -5.0 MPa 0.5 ≤D ≤ 1.5MPa 0.5 The following conditions are met. As a result, the elastomer and tackifier are more compatible in the adhesive layer 11, and the adhesive sheet 1a is more likely to have the desired adhesive strength to the adherend. The SP value is the Hiderbrand SP value. For example, the SP values ​​of the elastomer and tackifier can be estimated using the calculation software Hansen Solubility Parameters in Practice (HSPiP). In calculations using HSPiP, the molecular structure described in SMILES notation is input. Also, for example, the calculation of the SP values ​​of the elastomer and tackifier is done based on the composition of constituent units such as styrene.

[0028] The SP value of elastomers is, for example, 15-20 MPa. 0.5 Therefore, 16-20 MPa 0.5 It may also be 17-19 MPa 0.5 That's fine.

[0029] The SP value of the tackifier is, for example, 17-21 MPa. 0.5 Therefore, 18-21 MPa 0.5 That's fine.

[0030] In the adhesive layer 11, D is -4.5 MPa 0.5It may be greater than or equal to -4.0 MPa 0.5 It may be greater than or equal to -3.5 MPa 0.5 It may be greater than or equal to -3.0 MPa 0.5 It may be greater than or equal to -2.5 MPa 0.5 It may be greater than or equal to -2.0 MPa 0.5 The above is also acceptable. D is 1.5 MPa 0.5 The following is also acceptable: 1.0 MPa 0.5 The following is also acceptable: 0.5 MPa 0.5 The following is also acceptable: 0 MPa 0.5 The following is also acceptable: -0.5 MPa 0.5 The following is also acceptable: -1.0 MPa 0.5 The following is also acceptable.

[0031] The tensile strength of the elastomer contained in the adhesive layer 11 is not limited to a specific value. Its tensile strength is, for example, 10 MPa or more. This results in a tensile force F A The material tends to become larger, making the adhesive sheet 1a less likely to break when peeled off from the substrate after being exposed to a high-temperature environment for a long period of time.

[0032] 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, or 45 MPa or less, or 40 MPa or less.

[0033] The elastomer contained in the adhesive layer 11 is, for example, a styrene block copolymer. Examples of styrene block copolymers 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.

[0034] The tackifier is not limited to a specific substance as long as it has a softening point of 100°C or higher. The tackifier is, for example, a predetermined resin. Examples of such resins include rosin-based tackifiers, terpene-based tackifiers, hydrocarbon-based tackifiers, phenol-based tackifiers, ketone-based tackifiers, polyamide-based tackifiers, epoxy-based tackifiers, and elastomer-based tackifiers. Examples of rosin-based tackifiers include unmodified rosin, modified rosin, rosin-phenol-based resins, and rosin-ester-based resins. Examples of terpene-based tackifiers 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 tackifiers 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, xyleneformaldehyde resins, resols, and novolacs. The tackifier is preferably an alicyclic hydrocarbon or an aromatic hydrocarbon resin.

[0035] 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.

[0036] The adhesive layer 11 may contain a filler. This makes it easier to adjust the tack of the adhesive layer 11 to a desired range. The material of the filler is not limited to a specific material. The filler may contain, 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 not contain a filler.

[0037] The filler content in the adhesive layer 11 is not limited to a specific value. The ratio of the filler content to the elastomer content in the adhesive layer 11 is, for example, 0.05 or more by mass, may be 0.1 or more, or 0.2 or more. The ratio may be, for example, 3 or less, may be 2.5 or less, may be 2 or less, may be 1.5 or less, may be 1 or less, or may be 0.5 or less.

[0038] The adhesive sheet 1a can be modified in various ways. For example, the adhesive sheet 1a may be configured as the adhesive sheet 1b shown in Figure 3. The adhesive sheet 1b is configured in the same way as the adhesive sheet 1a, except for the parts that are not specifically described. Components of the adhesive sheet 1b that are the same as or correspond to components of the adhesive sheet 1a are given the same reference numerals, and detailed descriptions are omitted. Descriptions of the adhesive sheet 1a also apply to the adhesive sheet 1b, insofar as they do not technically contradict each other.

[0039] As shown in Figure 3, the adhesive sheet 1b comprises a foamed base material 12, and the adhesive layer 11 is placed on the base material 12. With this configuration, the foamed base material 12 can easily deform to conform to the object to be adhered to, and even when the distance between objects to be adhered to is relatively large, the gaps between objects can be easily filled by the adhesive sheet 1b.

[0040] The adhesive sheet 1b comprises, for example, a pair of adhesive layers 11, and the base material 12 is placed between the adhesive layers 11. The pair of adhesive layers 11 form the first surface 11a and the second surface 11b, which are the end faces in the thickness direction of the adhesive sheet 1b. The adhesive sheet 1b may be modified to include one adhesive layer in contact with one main surface of the base material 12.

[0041] The base material 12 may, for example, have a closed-cell structure, an open-cell structure, or a semi-closed, semi-open-cell structure. If the base material 12 has a semi-closed, semi-open-cell structure, it contains open cells before compression deformation, and when the base material 12 is compressed to the extent that, for example, a compression strain of 50% or more occurs, the open parts close up, and it changes to a structure similar to that of a closed-cell structure.

[0042] The material forming the base material 12 is not limited to a specific material. The base material 12 may be, for example, rubber foam, urethane foam, silicone foam, or acrylic foam.

[0043] When the base material 12 is a rubber foam, the rubber may be an olefin-based elastomer, a styrene-based elastomer, a butyl-based elastomer, a vinyl chloride-based elastomer, or natural rubber. Examples of olefin-based elastomers are ethylene-propylene rubber (EPM) and ethylene-propylene-diene rubber (EPDM). Examples of styrene-based elastomers are 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-based elastomers are butyl rubber, polyisobutylene rubber, polybutene, polyisoprene rubber, and nitrile butadiene rubber (NBR). Examples of vinyl chloride-based elastomers include chloroprene rubber and chlorosulfonated polyethylene rubber.

[0044] The thickness of the base material 12 is not limited to a specific value. For example, the thickness of the base material 12 may be 0.5 to 40 mm, 1 to 40 mm, 1 to 30 mm, 1 mm to 20 mm, or 2 to 20 mm. [Examples]

[0045] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0046] <Example 1> A mixture was obtained by kneading SBS resin D1155 manufactured by Kraton Corporation and tackifier Alcon M-115 manufactured by Arakawa Chemical Industries, Ltd. in a ratio of 100 parts by mass and 35 parts by mass, respectively. This mixture was hot-pressed at 150°C and 4 MPa to obtain an adhesive sheet according to Example 1 having a thickness of 100 μm. The styrene content of SBS resin D1155 was 40% by mass. The softening point of Alcon M-115 was 115°C according to the ring-and-ball method.

[0047] <Examples 2 and 3> Adhesive sheets according to Example 2 and Example 3 were obtained in the same manner as in Example 1, except that the amount of tackifier added was changed to 10 parts by mass and 50 parts by mass, respectively.

[0048] <Example 4> An adhesive sheet according to Example 4 was obtained in the same manner as in Example 1, except that Toughprene A, an SBS resin manufactured by Asahi Kasei Corporation, was used instead of SBS resin D1155. Toughprene is a registered trademark. The thickness of the adhesive sheet according to Example 4 was 300 μm. The styrene content in Toughprene A was 40% by mass.

[0049] <Example 5> An adhesive sheet according to Example 5 was obtained in the same manner as in Example 1, except that TR-2003 SBS resin manufactured by ENEOS Material was used instead of SBS resin D1155. The thickness of the adhesive sheet according to Example 5 was 100 μm. The styrene content in TR-2003 was 43% by mass.

[0050] <Example 6> A mixture was obtained by kneading SBS resin TR-2003 manufactured by ENSOS Material, tackifier Alcon M-115 manufactured by Arakawa Chemical Industries, and heavy calcium carbonate filler manufactured by Maruo Calcium in proportions of 100 parts by mass, 40 parts by mass, and 35 parts by mass, respectively. This mixture was hot-pressed at 150°C and 4 MPa to obtain the adhesive sheet according to Example 6, having a thickness of 100 μm.

[0051] <Example 7> An adhesive sheet was obtained in the same manner as in Example 1. An adhesive sheet was attached to one main surface of Nitto Denko's EE-1000 foam to obtain a laminate. The EE-1000 foam was an EPDM foam with an open-cell structure. The thickness of the EE-1000 foam was 5 mm. The laminate was bonded to the foam by applying a pressure of 2 kPa for 5 minutes in an oven maintained at 140°C. In this way, an adhesive sheet according to Example 7 was obtained.

[0052] <Example 8> An adhesive sheet according to Example 8 was obtained in the same manner as in Example 7, except that Super Sheet H, a urethane foam manufactured by Nippon Hatsujo Co., Ltd., was used instead of foam EE-1000.

[0053] <Example 9> An adhesive sheet according to 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 foam EE-1000.

[0054] <Example 10> An adhesive sheet according to 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.

[0055] <Example 11> An adhesive sheet according to Example 11 was obtained in the same manner as in Example 1, except that the amount of tackifier was changed to 70 parts by mass and the thickness of the adhesive sheet was adjusted to 300 μm.

[0056] <Comparative Examples 1 and 2> Adhesive sheets according to Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the amount of tackifier added was changed to 5 parts by mass and 70 parts by mass, respectively.

[0057] <Comparative Example 3> A sticky sheet according to Comparative Example 3 was obtained in the same manner as in Example 1, except that SBS resin D0243 manufactured by Kraton was used instead of SBS resin D1155. The styrene content of SBS resin D0243 was 24% by mass.

[0058] <Comparative Example 4> A tack sheet according to Comparative Example 4 was obtained in the same manner as in Example 1, except that the tackifier T-REZ RB100 manufactured by ENEOS Corporation was used instead of the tackifier Alcon M-115. The softening point of T-REZ RB100 was 100°C according to the ring-and-ball method.

[0059] <Comparative Example 5> A tack sheet according to Comparative Example 5 was obtained in the same manner as in Example 1, except that the tackifier Pencel C manufactured by Arakawa Chemical Industries, Ltd. was used instead of the tackifier Alcon M-115. The softening point of Pencel C was 120°C according to the ring-and-ball method.

[0060] <Comparative Example 6> A tack sheet according to Comparative Example 6 was obtained in the same manner as in Example 1, except that the tackifier Alcon M90 manufactured by Arakawa Chemical Industries, Ltd. was used instead of the tackifier Alcon M-115. The softening point of Alcon M90 was 90°C according to the ring-and-ball method.

[0061] <Comparative Example 7> A comparative adhesive sheet according to Comparative Example 7 was obtained in the same manner as in Example 1, except that Quintac3433N SIS resin manufactured by Nippon Zeon Co., Ltd. was used instead of SBS resin D1155. The styrene content of Quintac3433N was 15% by mass. Quintac is a registered trademark.

[0062] <Comparative Example 8> A sticky sheet according to Comparative Example 8 was obtained in the same manner as in Example 1, except that the amount of tackifier added was changed to 100 parts by mass.

[0063] (SP value) The Hiderbrand SP values ​​of the SBS resin, SIS resin, and tackifier used in each example and comparative example were calculated using the HSPiP calculation software. In this calculation, the molecular structure was entered according to SMILES notation, and the composition of each constituent unit in the SBS resin and SIS resin was taken into consideration. In addition, the difference D was calculated by subtracting the SP value of the tackifier from the SP value of the SBS resin or SIS resin. The results are shown in Tables 1 and 2.

[0064] (Tensile test) Tensile tests were performed using the adhesive sheets of each example and comparative example, as well as test specimens made from the SBS resin and SIS resin used in each example or comparative example. The test specimens were rectangular in shape, with a width of 10 mm and a length of 40 mm in plan view. Tensile tests were performed at room temperature, a test speed of 1000 mm / min, and a chuck distance of 10 mm. Other conditions for the tensile tests were determined in accordance with JIS K6251. Tensile strength [MPa] and tensile force F A The values ​​were calculated according to the following formulas (1) and (2). The results are shown in Tables 1 and 2. Tensile strength [MPa] = Maximum test force [N] / Cross-sectional area of ​​the test specimen [mm²] 2 ] Formula (1) Tensile force F A [N / 20mm] = 20mm × specimen thickness [mm] × maximum test force [N] / cross-sectional area of ​​specimen [mm] 2 ] Formula (2)

[0065] (Measurement of adhesive strength after peeling at a 90° angle) Test specimens were prepared using the adhesive sheets of each example and comparative example. The test specimens were rectangular in shape, with a length of 100 mm and a width of 20 mm in plan view. A 50 μm polyethylene terephthalate (PET) film was laminated to one main surface of the test specimen for backing. The foam or foam of the adhesive sheet according to Examples 7-10 and the PET film for backing were attached using Nitto Denko's acrylic double-sided adhesive tape No. 5000NS. This test specimen was placed on a 1.5 mm thick test plate made of SUS304, and a 2 kg roller was rolled back and forth once over the test specimen to adhere it. After attaching the test specimen to the test plate, no load was applied to the test specimen, and it was peeled off within 1 minute of attachment. The initial 90° peel adhesion strength F was measured in accordance with JIS Z 0237:2022. C The measurement was taken. The peeling speed was adjusted to 300 mm / min. The results are shown in Tables 1 and 2.

[0066] Except for the points listed below, the initial 90° peel-off adhesive strength is F. C Similarly, the peel adhesion strength after the durability test was measured. After attaching the test specimens to the test board, no load was applied to the specimens, and the specimens were stored together with the test board in an oven maintained at 100°C for 7 days. After that, the specimens were removed from the oven, allowed to cool at room temperature for 1 hour, and then the 90° peel adhesion strength F was measured in accordance with JIS Z 0237:2022. B The following measurements were taken. The results are shown in Tables 1 and 2.

[0067] (Evaluation of the recoverability of adhesive sheets) The adhesive sheets for each example and comparative example were placed on a 1.5 mm thick SUS304 plate, and a 2 kg roller was passed back and forth once over the adhesive sheet to adhere it to the plate. The test specimens were stored together with the test plate in an oven maintained at 100°C for 7 days. After that, the test specimens were removed from the oven and allowed to cool at room temperature for 1 hour, and then the edges of the adhesive sheets were grasped by hand and peeled off from the plate at a speed of approximately 300 mm / min. In this case, the recoverability of the adhesive sheets was evaluated according to the following criteria. The results are shown in Table 1. OK: The adhesive sheet did not break, and there is no adhesive residue on the board material from the adhesive sheet. NG: It is confirmed that the adhesive sheet breaks and / or adhesive residue from the adhesive sheet remains on the board material.

[0068] As shown in Tables 1 and 2, the adhesive sheet according to the example has the following characteristics (a), (b), and (c), and in the example, the tensile force F A >Adhesive force F B The conditions were met. In addition, it was confirmed that the recoverability of the adhesive sheet according to the example was better than that of Comparative Examples 2, 3, 6, and 7. Therefore, it was suggested that the adhesive sheet according to the example is easily recoverable by peeling even after being exposed to a high-temperature environment for a long period of time after being attached to a substrate. In addition, the initial 90° peel adhesive strength F of the adhesive sheet according to each example C The tensile strength was 1.0 N / 20 mm or higher. The initial adhesive strength of the adhesive sheets in each example was higher than the initial adhesive strength of the adhesive sheets in Comparative Examples 1, 4, and 5, suggesting that the adhesive sheets in each example exhibit good adhesive strength from the beginning. According to the examples, the tensile strength F was obtained while exhibiting a predetermined adhesive strength from the beginning. A >Adhesive force F B It was suggested that it is possible to achieve these conditions. (a) The elastomer (SBS resin) contains 25% or more styrene by mass. (b) The softening point of the tackifier is 100°C or higher. (c) Ratio of the mass of the tackifier to the mass of the elastomer ET The values ​​are between 0.1 and 0.8.

[0069] On the other hand, in Comparative Example 1, ratio R ET The initial 90° peel adhesion strength F is 0.05. C It was small. In Comparative Example 2, ratio R ET The tensile force F is 0.7. A >Adhesive force F B The conditions were not met. In Comparative Example 3, the styrene content in the SBS resin was 24% by mass, and the tensile force F A >Adhesive force FB The conditions were not satisfied. In Comparative Examples 4 and 5, the initial 90° peel adhesion force F C was small. In order for the adhesive sheet to exhibit the desired adhesiveness, it was suggested that the difference D in SP value be within a predetermined range (for example, -5.0 MPa 0.5 or more and 1.5 MPa 0.5 or less). In Comparative Example 6, the softening point of the tackifier was 90°C, and the tensile force F A > adhesion force F B The condition was not satisfied. In Comparative Example 7, the styrene content in the SIS resin was 15% by mass, and the tensile force F A > adhesion force F B The condition was not satisfied.

[0070] A first aspect of the present invention is an adhesive sheet comprising an adhesive layer containing an elastomer containing 25% or more styrene by mass and a tackifier having a softening point of 100°C or higher, the ratio of the content of the tackifier to the content of the elastomer in the adhesive layer is 0.1 to 0.8 by mass, the adhesive sheet satisfies the condition that the tensile force F A [N / 20 mm]> adhesion force F B [N / 20 mm], the tensile force F A is represented by F1·t 2 ·20 / S1 in a tensile test performed on a test piece prepared from the adhesive sheet, where F1 is the maximum test force in the tensile test, S1 is the cross-sectional area of the test piece [mm A , and t is the thickness of the adhesive sheet A [mm], the adhesive sheet has an adhesion force F of​​​​​​​​​​B is the 90° peel adhesion force [N / 20 mm] measured by peeling the test piece from the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022 after maintaining the environmental temperature of the test piece at 100°C for 7 days in a state where the test piece made from the adhesive sheet is attached to the test plate, the adhesive force F C is the 90° peel adhesion force [N / 20 mm] measured by peeling the adhesive sheet from the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022 within 1 minute after attaching the test piece made from the adhesive sheet to the test plate, provides an adhesive sheet.

[0071] The second aspect of the present invention is D, which is the difference obtained by subtracting the SP value of the tackifier from the SP value of the elastomer, is -5.0 MPa 0.5 ≦D≦1.5 MPa 0.5 satisfies the condition of provides an adhesive sheet according to the first aspect.

[0072] The third aspect of the present invention is the elastomer has a tensile strength of 10 MPa or more, provides an adhesive sheet according to the first aspect or the second aspect.

[0073] The fourth aspect of the present invention is the tensile force F A is 10 N / 20 mm or more, provides the adhesive sheet described in any one of the first aspect to the third aspect. provides the adhesive sheet described in any one of the first aspect to the fourth aspect.

[0074] The fifth aspect of the present invention is further includes a base material that is a foam, the adhesive layer is disposed on the base material, provides the adhesive sheet described in any one of the first aspect to the fourth aspect.

[0075] [Table 1]

[0076] [Table 2] [Explanation of symbols]

[0077] 1a, 1b Adhesive sheets 11 Adhesive layer 12 Base material

Claims

1. It is an adhesive sheet, The adhesive layer comprises an elastomer containing 25% or more styrene by mass and a tackifier having a softening point of 100°C or higher. The ratio of the content of the tackifier to the content of the elastomer in the adhesive layer is 0.1 to 0.8 by mass. The aforementioned adhesive sheet is subjected to a tensile force F A [N / 20mm]>Adhesive force F B Satisfying the condition [N / 20mm], The tensile force F A is the maximum test force F in a tensile test performed on a test piece made from the adhesive sheet 1 , the cross-sectional area S of the test piece 1 [mm 2 , and the thickness t of the adhesive sheet A [mm], and is represented by F 1 ·t A ·20 / S 1 and is expressed as The aforementioned adhesive sheet has an adhesive strength F of 1.0 N / 20 mm or more. C It has, The test specimen in the tensile test is rectangular in shape, having a width of 10 mm and a length of 40 mm in plan view. The distance between the chucks in the aforementioned tensile test was 10 mm. The test speed in the aforementioned tensile test was 1000 mm / min. The aforementioned adhesive force F B This is the 90° peel adhesion strength [N / 20mm] measured by peeling off the test specimen from the test plate in accordance with Japanese Industrial Standard (JIS) Z 0237:2022, after maintaining the ambient temperature of the test specimen at 100°C for 7 days with the test specimen attached to the test plate. The aforementioned adhesive force F C This is the 90° peel adhesion strength [N / 20mm] measured by peeling the adhesive sheet from the test plate within one minute after attaching the test piece made from the adhesive sheet to the test plate, in accordance with Japanese Industrial Standard (JIS) Z 0237:2022. Adhesive sheet.

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

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

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

5. The base material is further made of foam, The adhesive layer is disposed on the substrate. The adhesive sheet according to claim 1.

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