Adhesive tape and electronic device

Abstract

The purpose of the present invention is to provide an adhesive tape having excellent impact absorption properties. Another purpose of the present invention is to provide an electronic device including the adhesive tape. The present invention is an adhesive tape comprising an adhesive layer that has a foamed structure, the adhesive tape being characterized in that the adhesive layer contains an acrylic copolymer having a constituent unit derived from a (meth)acrylic compound, and the (meth)acrylic compound includes a (meth)acrylic compound having an SP value of 9.45 (cal / cm3)1 / 2 or less.

Description

Adhesive tape, and electronic device

[0001] The present invention relates to an adhesive tape. Further, the present invention relates to an electronic device including the adhesive tape.

[0002] Conventionally, when fixing parts in various industrial applications such as electronic devices, vehicles, houses, and building materials, an adhesive tape having an adhesive layer containing an adhesive has been widely used (for example, Patent Documents 1 to 3). Specifically, for example, an adhesive tape is used to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module and a display panel module.

[0003] JP-A-2015-052050, JP-A-2015-021067, JP-A-2015-120876

[0004] An adhesive tape used for fixing a panel such as a smartphone or a tablet to a housing or the like is required to be an adhesive tape having excellent shock absorbency in order to prevent peeling or breakage of parts due to an impact during a fall. In recent years, electronic devices tend to be thinner, and the demand for an adhesive tape having even better shock absorbency is increasing more and more.

[0005] An object of the present invention is to provide an adhesive tape having excellent shock absorbency. Another object of the present invention is to provide an electronic device including the adhesive tape.

[0006] The present disclosure 1 is an adhesive tape having an adhesive layer having a foamed structure, the adhesive layer containing an acrylic copolymer having a structural unit derived from a (meth)acrylic compound, and the (meth)acrylic compound having an SP value of 9.45 (cal / cm ３ ) １／２ as follows. The present disclosure 2 is the above SP value in the acrylic copolymer of 9.45 (cal / cm ３ ) １／２Disclosure 1 is an adhesive tape of this disclosure in which the content of constituent units derived from the (meth)acrylic compound described below is 5% by mass or more and 85% by mass or less. Disclosure 3 is an adhesive tape of this disclosure 1 or 2 in which the (meth)acrylic compound contains an alkyl (meth)acrylate having an alkyl group having 12 or more carbon atoms. Disclosure 4 is an adhesive tape of this disclosure 1, 2 or 3 in which the (meth)acrylic compound contains a macromonomer having a (meth)acryloyl group and a number average molecular weight of 2,000 or more and 30,000 or less. Disclosure 5 is an adhesive tape of this disclosure 4 in which the macromonomer having a (meth)acryloyl group and a number average molecular weight of 2,000 or more and 30,000 or less contains constituent units derived from an olefin polymer having a (meth)acryloyl group at its terminus. Disclosure 6 is an adhesive tape of this disclosure 5 in which the content of constituent units derived from the olefin polymer having a (meth)acryloyl group at its terminus in the acrylic copolymer is 5% by mass or more and 30% by mass or less. Disclosure 7 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, or 6, wherein the (meth)acrylic compound comprises a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms, and the content of the structural unit derived from the alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms in the acrylic copolymer is 30% by mass or more and less than 100% by mass. Disclosure 8 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, or 7, wherein the (meth)acrylic compound comprises an alkyl (meth)acrylate having a linear or branched alkyl group having 6 to 8 carbon atoms. Disclosure 9 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, or 8, wherein the (meth)acrylic compound comprises an alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure. Disclosure 10 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the (meth)acrylic compound contains a monomer having a crosslinkable functional group, and the content of constituent units derived from the monomer having a crosslinkable functional group in the acrylic copolymer is 0.1% by mass or more.Disclosure 11 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the acrylic copolymer has constituent units derived from a vinyl aromatic compound, and the content ratio of constituent units derived from the vinyl aromatic compound in the acrylic copolymer is 2.5% by mass or more and 15% by mass or less. Disclosure 12 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, wherein the acrylic copolymer has a weight-average molecular weight of 300,000 or more and 1,500,000 or less. Disclosure 13 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, wherein the adhesive layer contains at least one elastomer selected from the group consisting of styrene elastomers, olefin elastomers, and urethane elastomers. Disclosure 14 is an adhesive tape according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, wherein the adhesive layer does not contain a tackifying resin, or the adhesive layer contains a tackifying resin, with the content of the tackifying resin being 50 parts by mass or less per 100 parts by mass of the acrylic copolymer. Disclosure 15 is an adhesive tape according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, wherein the adhesive layer contains a coloring agent. Disclosure 16 is an adhesive tape according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, wherein the adhesive layer has a structure derived from a crosslinking agent. Disclosure 17 is an adhesive tape according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, wherein the adhesive layer has bubbles derived from foaming particles. Disclosure 18 is an adhesive tape according to Disclosure 17, wherein the foaming particles include thermally expandable microcapsules. Disclosure 19 is an adhesive tape according to Disclosures 17 or 18, wherein the foaming particles have an average particle size of 60 μm or less. Disclosure 20 is an adhesive tape according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19, wherein the adhesive layer has a gel fraction of 10% by mass or more and 70% by mass or less.Disclosure 21 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, wherein the adhesive layer has a bio-derived carbon content of 15% or more. Disclosure 22 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21, wherein the adhesive layer has an average major diameter of bubbles of 0.80 times or less the thickness of the adhesive layer. Disclosure 23 is an adhesive tape according to Disclosure 23, wherein the adhesive layer has a deemed density of 0.59 g / cm³. ３ 1.15g / cm or more ３The following are adhesive tapes according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22. Disclosure 24 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23, wherein the adhesive layer has a structure in which no air bubbles are exposed on the surface in the thickness direction. Disclosure 25 is an adhesive tape according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24, which does not have a base material. Disclosure 26 is an adhesive tape of Disclosure 25, comprising only the adhesive layer described above. Disclosure 27 is an adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24, having a base material and having the adhesive layer described above on at least one surface of the base material. Disclosure 28 is an adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or 27, having a second adhesive layer without a foamed structure on at least one surface of the adhesive layer described above. Disclosure 29 is an adhesive tape according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, or 28, wherein the adhesive tape has a 180° peel force of 10 N / 25 mm or more at 23°C on the side of the adhesive layer having the foamed structure. Disclosure 30 is an adhesive tape according to Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, used for bonding and fixing internal components of electrical and electronic equipment or automotive components. Disclosure 31 is an electronic device comprising the adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30. The present invention will be described in detail below.Hereinafter, an embodiment of the present invention or one thereof will be described as "this embodiment".

[0007] The inventors of the present invention considered using a monomer having a solubility parameter (SP value) of a specific value or less as a monomer constituting an acrylic copolymer contained in an adhesive layer having a foamed structure for the adhesive layer of the adhesive tape. As a result, they found that an adhesive tape excellent in shock absorption can be obtained, and thus completed the present invention.

[0008] The adhesive tape of this embodiment has an adhesive layer having a foamed structure. The adhesive tape of this embodiment has an adhesive layer having a foamed structure, and the adhesive layer having the foamed structure has a solubility parameter (SP value) of 9.45 (cal / cm ３ ), １／２ which is described below, and by having a structural unit derived from a (meth)acrylic compound, the stress relaxation property of the adhesive layer is improved. As a result, the adhesive tape of this embodiment is excellent in shock absorption.

[0009] Examples of the method for forming a foamed structure in the adhesive layer include, for example, a method of forming a foamed structure by incorporating foaming particles into an adhesive composition for forming the adhesive layer, applying the composition to a release film or the like, and then heating and drying it; a method of forming a foamed structure by forcibly mixing and dispersing a gas into an adhesive composition for forming the adhesive layer; and a method of forming a foamed structure by mixing a liquefied gas into an adhesive composition for forming the adhesive layer. Among these, from the viewpoint that bubbles formed in the adhesive layer are easily dispersed when the adhesive composition is dried at a high temperature and the resulting adhesive tape has better shock absorption, a method of forming a foamed structure by incorporating foaming particles into the adhesive composition, applying the composition to a release film or the like, and then heating and drying it is preferable. That is, the adhesive layer preferably has bubbles derived from the foaming particles.

[0010] Examples of the foaming particles include those that foam by heating, and may be thermally expanded particles. Specifically, examples include thermally decomposable foaming agents, thermally expandable microcapsules, etc. Among these, the foaming particles preferably contain thermally expandable microcapsules.

[0011] The above-mentioned thermally expandable microcapsules are particles in which a volatile substance such as a low-boiling solvent is encapsulated inside a shell resin. When the shell resin is softened by heating and the encapsulated volatile substance volatilizes or expands, the shell expands due to the pressure and the particle diameter increases. Therefore, the thermally expandable microcapsules become hollow particles having bubbles inside the shell when heated. Therefore, in the above adhesive layer, since the foaming particles contain thermally expandable microcapsules, it is possible to prevent the gas generated from the foaming particles from escaping to the outside of the adhesive layer where it is formed, and it becomes easier to coexist an appropriate amount of bubbles in the adhesive layer. As a result, it becomes easier to improve the expansion ratio of the adhesive layer. As a result, the stress relaxation property of the adhesive layer is further improved, and the obtained adhesive tape has better shock absorption properties.

[0012] The shell resin of the above-mentioned thermally expandable microcapsules is preferably a thermoplastic resin. Examples of the thermoplastic resin include vinyl polymers such as ethylene, styrene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, butadiene, chloroprene, and copolymers thereof, polyamides such as nylon 6 and nylon 66, and polyesters such as polyethylene terephthalate. One or more resins selected from the above can be mentioned. Among them, a copolymer of acrylonitrile is preferable from the viewpoint that the encapsulated volatile substance is difficult to permeate and it is easy to adjust the average particle diameter of the foaming particles described later to a suitable range.

[0013] Examples of the volatile substance encapsulated inside the above-mentioned thermally expandable microcapsules include hydrocarbons having 3 to 7 carbon atoms such as propane, propylene, butene, normal butane, isobutane, isopentane, neopentane, normal pentane, hexane, and heptane, petroleum ether, methyl chloride, methylene chloride, and other halogenated methanes, CCl ３ F, CCl ２ F ２ One or more low-boiling liquids selected from chlorofluorocarbons such as etc., and tetraalkylsilanes such as tetramethylsilane and trimethylethylsilane can be mentioned. Among them, hydrocarbons having 3 to 7 carbon atoms are preferable.

[0014] The preferred upper limit for the average particle size of the foamed particles is 60 μm. A more preferable upper limit for the average particle size of the foamed particles is 55 μm, and an even more preferable upper limit is 50 μm. Furthermore, a preferred lower limit for the average particle size of the foamed particles is 15 μm. A more preferable lower limit for the average particle size of the foamed particles is 15 μm. A more preferable lower limit for the average particle size of the foamed particles is 15 μm or more. This improves the bending rigidity of the adhesive layer, allowing the adhesive tape of this embodiment to have excellent shock absorption while also improving resistance to deformation such as bending and twisting (deformation resistance). A more preferable lower limit for the average particle size of the foamed particles is 20 μm, and an even more preferable lower limit is 25 μm. Examples of the average particle size of the foamed particles include 15 μm to 60 μm, 20 μm to 55 μm, 25 μm to 50 μm, etc. Furthermore, in this specification, the "average particle size of the foaming particles" refers to the average particle diameter of the foaming particles in an unfoamed state, obtained by observing the adhesive composition containing the foaming particles. The average particle size of the foaming particles can also be obtained by randomly selecting particles using an optical microscope or the like and calculating the average of 10 points.

[0015] Furthermore, the expansion initiation temperature of the foaming particles (also called the "foaming initiation temperature") is not particularly limited, but examples include a temperature range of 95°C to 150°C. The "expansion initiation temperature of foaming particles" refers to the temperature at which the foaming particles begin to expand, and can be measured using a thermomechanical analyzer (TMA) or the like.

[0016] Examples of commercially available foaming particles include Expancel 920DU40 (manufactured by Nippon Philite Co., Ltd., average particle size 40 μm), Expancel 920DU80 (manufactured by Nippon Philite Co., Ltd., average particle size 80 μm), EMC-20(B)R (manufactured by Nippon Philite Co., Ltd., average particle size 20 μm), and Advancel EML101 (manufactured by Sekisui Chemical Co., Ltd., average particle size 50 μm).

[0017] The adhesive layer described above contains an acrylic copolymer having structural units derived from a (meth)acrylic compound. In this specification, "(meth)acrylic" means acrylic or methacrylic. In this specification, "(meth)acrylic compound" means a compound having a (meth)acryloyl group. Furthermore, in this specification, "(meth)acryloyl" means acryloyl or methacryloyl.

[0018] The above (meth)acrylic compound has an SP value of 9.45 (cal / cm³). ３ ) １／２ The present invention includes the following (meth)acrylic compound (hereinafter sometimes referred to as "(meth)acrylic compound (a)"). By having the above acrylic copolymer have constituent units derived from the above (meth)acrylic compound as constituent units derived from the above (meth)acrylic compound (a), the stress relaxation properties of the adhesive layer having the above foam structure are improved, and the adhesive tape of this embodiment has excellent shock absorption properties.

[0019] The reason why the adhesive tape of this embodiment can have excellent shock absorption properties due to the presence of a constituent unit derived from the above-mentioned (meth)acrylic compound (a) in the above-mentioned acrylic copolymer is not clear. However, it is presumed to be due to the following:

[0020] In other words, external impacts such as drops typically act on objects moving at high speeds. The behavior of an object subjected to such high-speed forces is highly correlated with the behavior of an object at low temperatures, based on the temperature-velocity conversion law. On the other hand, since the (meth)acrylic compound (a) has low polarity, the charge difference within the acrylic copolymer having constituent units derived from the (meth)acrylic compound (a) becomes small, and as a result the glass transition temperature of the adhesive layer becomes small, the adhesive layer becomes more pliable at low temperatures. Therefore, it is presumed that because the acrylic copolymer has constituent units derived from the (meth)acrylic compound (a), the adhesive layer becomes more pliable to external impacts such as drops, improving stress relaxation, and thus the adhesive tape of this embodiment exhibits excellent shock absorption.

[0021] The SP value of the above (meth)acrylic compound (a) is 9.45 (cal / cm³). ３ ) １／２ The following is acceptable, but the preferred upper limit is 9.30 (cal / cm³). ３ ) １／２ The SP value of the above (meth)acrylic compound (a) is 9.30 (cal / cm³). ３ ) １／２ The following conditions result in the adhesive tape of this embodiment having superior shock absorption properties. A more preferable upper limit for the SP value of the (meth)acrylic compound (a) is 9.20 (cal / cm³). ３ ) １／２ A more preferable upper limit is 8.50 (cal / cm³). ３ ) １／２ A more preferable upper limit is 8.40 (cal / cm³). ３ ) １／２ Furthermore, there is no particular lower limit for the SP value of the above (meth)acrylic compound (a), but 8.35 (cal / cm³) is acceptable. ３ ) １／２ This degree represents the practical lower limit. For example, the SP value of the (meth)acrylic compound in the above constituent unit (a) is 8.35 (cal / cm³). ３ ) １／２ More than 9.45 (cal / cm ３ ) １／２ Below, 8.35 (cal / cm ３ ) １／２ 9.30 (cal / cm) ３ ) １／２ Below, 8.35 (cal / cm ３ ) １／２ More than 9.20 (cal / cm ３ ) １／２ Below, 8.35 (cal / cm ３ ) １／２ More than 8.50 (cal / cm ３ ) １／２ Below, 8.35 (cal / cm ３ ) １／２ 8.40 (cal / cm) ３ ) １／２ The following are some examples.

[0022] In this specification, "SP value" is also called the solubility parameter and is an index that can represent the ease of solubility, calculated using the Fedors method (R.F. Fedors, Polym. Eng. Sci., 14(2), 147-154 (1974)) (unit = (cal / cm³) ３ ) １／２ ).

[0023] In the above acrylic copolymer, the preferred lower limit for the content of constituent units derived from the (meth)acrylic compound (a) is 5% by mass, and the preferred upper limit is 85% by mass. When the content of constituent units derived from the (meth)acrylic compound (a) is 5% by mass or more, the adhesive tape of this embodiment has better shock absorption properties. When the content of constituent units derived from the (meth)acrylic compound (a) is 85% by mass or less, the adhesive tape of this embodiment maintains excellent shock absorption properties while being more easily given better deformation resistance (especially bending resistance). A more preferred lower limit for the content of constituent units derived from the (meth)acrylic compound (a) is 8% by mass, a more preferred upper limit is 75% by mass, an even more preferred lower limit is 15% by mass, an even more preferred upper limit is 65% by mass, an even more preferred lower limit is 20% by mass, and an even more preferred upper limit is 50% by mass. Examples of the content ratio of constituent units derived from the above (meth)acrylic compound (a) include 5% by mass or more and 85% by mass or less, 8% by mass or more and 75% by mass or less, 15% by mass or more and 65% by mass or less, 20% by mass or more and 50% by mass or less.

[0024] From the viewpoint of increasing the free volume and thereby further enhancing the flexibility of the adhesive layer, it is preferable that the (meth)acrylic compound (a) includes an alkyl (meth)acrylate having an alkyl group with 12 or more carbon atoms (hereinafter sometimes referred to as "(meth)acrylic compound (a-1)"). Furthermore, from the viewpoint of further improving the cohesive force between side chains in the acrylic copolymer, it is preferable that the alkyl (meth)acrylate having an alkyl group with 12 or more carbon atoms includes an alkyl (meth)acrylate having an alkyl group with 130 or fewer carbon atoms.

[0025] The above (meth)acrylic compound (a-1) is, for example, lauryl acrylate (SP value: 9.15 (cal / cm³) ３ ) １／２ ), isostearyl acrylate (SP value: 8.46 (cal / cm³) ３ ) １／２ Examples of constituent units derived from ) etc.

[0026] When the above acrylic copolymer has constituent units derived from the above (meth)acrylic compound (a-1), the preferred lower limit of the content of constituent units derived from the above (meth)acrylic compound (a-1) in the acrylic copolymer is 4% by mass, and the preferred upper limit is 50% by mass. By having a content of 4% by mass or more of constituent units derived from the above (meth)acrylic compound (a-1), the adhesive tape of this embodiment can obtain higher shock absorption. By having a content of 50% by mass or less of constituent units derived from the above (meth)acrylic compound (a-1), the adhesive layer can exhibit stable adhesive strength to a wide range of materials, thus further improving the handling of the adhesive tape of this embodiment. A more preferred lower limit of the content of constituent units derived from the above (meth)acrylic compound (a-1) is 6% by mass, a more preferred upper limit is 45% by mass, an even more preferred lower limit is 8% by mass, and an even more preferred upper limit is 40% by mass. Examples of the content ratio of constituent units derived from the above (meth)acrylic compound (a-1) include 4% by mass or more and 50% by mass or less, 6% by mass or more and 45% by mass or less, and 8% by mass or more and 40% by mass or less.

[0027] From the viewpoint of increasing the free volume of the acrylic copolymer and facilitating aggregation between side chains, it is preferable that the (meth)acrylic compound (a) contains a macromonomer having a (meth)acryloyl group and a number average molecular weight of 2,000 to 30,000 (hereinafter sometimes referred to as "(meth)acrylic compound (a-2)").

[0028] The number-average molecular weight of the above (meth)acrylic compound (a-2) is not particularly limited as long as it is between 2,000 and 30,000. However, from the viewpoint of increasing the free volume of the above acrylic copolymer and facilitating aggregation between side chains, a preferred lower limit is 4,000, a preferred upper limit is 25,000, a more preferred lower limit is 5,000, and a more preferred upper limit is 23,000. Examples of the number-average molecular weight of macromonomers having the above (meth)acryloyl group and having a number-average molecular weight between 2,000 and 30,000 include those between 4,000 and 25,000, and those between 5,000 and 23,000. In this specification, "weight-average molecular weight" and "number-average molecular weight" refer to the weight-average molecular weight and number-average molecular weight measured as polystyrene-equivalent molecular weight by gel permeation chromatography (GPC). For example, the weight-average molecular weight and number-average molecular weight can be measured using a Waters 2690 Separations Module as the measuring instrument, a Showa Denko GPC KF-806L as the column, a sample flow rate of 1 mL / min, and a column temperature of 40°C.

[0029] Examples of the (meth)acrylic compound (a-2) mentioned above include styrene polymers having (meth)acryloyl groups at the terminals and olefin polymers having (meth)acryloyl groups at the terminals. In particular, from the viewpoint of providing the resulting adhesive tape with improved shock absorption and excellent deformation resistance (especially bending resistance), it is preferable to include an olefin polymer having (meth)acryloyl groups at the terminals.

[0030] Furthermore, it is preferable that the above acrylic copolymer has, as constituent units derived from the above (meth)acrylic compound, constituent units derived from alkyl (meth)acrylate ester and constituent units derived from an olefin polymer having a (meth)acryloyl group at its terminal. When the above acrylic copolymer has such a configuration, the above acrylic copolymer has a structure in which constituent units derived from alkyl acrylate ester are the main chain and constituent units derived from an olefin polymer having a (meth)acryloyl group at its terminal are the side chains. In this structure, the constituent units derived from the olefin polymer having a (meth)acryloyl group at its terminal, located in the side chains of the above acrylic copolymer, aggregate through interaction and form a pseudo-crosslink. Therefore, when the adhesive layer is subjected to impact and the strain increases, the pseudo-crosslink breaks, making the molecules of the above acrylic copolymer more easily stretched, so that the adhesive layer becomes more flexible and has excellent stress relaxation properties. As a result, the resulting adhesive tape has better shock absorption properties.

[0031] Furthermore, when the acrylic copolymer has the above-mentioned structure, if the strain is small, the molecules of the acrylic copolymer become hard as if they were in a crosslinked structure due to the above-mentioned pseudo-crosslinking, and the adhesive layer has appropriate hardness. As a result, the resulting adhesive tape has excellent deformation resistance (especially bending resistance). Also, when the strain applied to the adhesive layer is small, the cohesive force of the adhesive layer is further improved, and the adhesive strength of the adhesive tape of this embodiment is further improved.

[0032] The olefin polymer having a (meth)acryloyl group at one end may have a (meth)acryloyl group at one end or at both ends. Among these, the olefin polymer having a (meth)acryloyl group at one end is preferred because it is less prone to intramolecular chemical crosslinking, the cohesive force of the adhesive layer is increased, and it has appropriate hardness, thereby providing the resulting adhesive tape with excellent deformation resistance (especially bending resistance).

[0033] Examples of olefin polymers having (meth)acryloyl groups include ethylene macromonomers having a (meth)acryloyl group at one end, propylene macromonomers having a (meth)acryloyl group at one end, polybutadiene or its hydrogenated products having a (meth)acryloyl group at one end (such as ethylene-butylene macromonomers having a (meth)acryloyl group at one end), and ethylene-propylene macromonomers having a (meth)acryloyl group at one end. Among these, ethylene-butylene macromonomers having a (meth)acryloyl group at one end are preferred from the viewpoint of facilitating aggregation between the side chains of the acrylic copolymer.

[0034] When the above acrylic copolymer has constituent units derived from the above (meth)acrylic compound (a-2), which are constituent units derived from an olefin polymer having (meth)acryloyl groups at its ends, the preferred lower limit of the content of constituent units derived from the olefin polymer having (meth)acryloyl groups at its ends in the above acrylic copolymer is 5% by mass, and the preferred upper limit is 30% by mass. When the content of constituent units derived from the olefin polymer having (meth)acryloyl groups at its ends is 5% by mass or more, an appropriate number of pseudo-crosslinks are formed. As a result, the adhesive layer has an appropriate hardness, and the resulting adhesive tape can be given better deformation resistance (especially bending resistance). When the content of constituent units derived from the olefin polymer having (meth)acryloyl groups at its ends is 30% by mass or less, the adhesive layer has an appropriate flexibility, and the shock absorption of the resulting adhesive tape is further improved. A more preferable lower limit for the content of constituent units derived from the olefin polymer having (meth)acryloyl groups at the terminals is 8% by mass, a more preferable upper limit is 25% by mass, an even more preferable lower limit is 10% by mass, and an even more preferable upper limit is 20% by mass. Examples of the content of constituent units derived from the olefin polymer having (meth)acryloyl groups at the terminals include 5% by mass or more and 30% by mass or less, 8% by mass or more and 25% by mass or less, 10% by mass or more and 20% by mass or less, etc.

[0035] A macromonomer having the above-mentioned (meth)acryloyl group and having a number-average molecular weight of 2,000 to 30,000 is specifically, for example, HPVM-L-1253 (ethylene-butylene macromonomer having a (meth)acryloyl group at one end, manufactured by Kraton Polymers, SP value: 8.31 (cal / cm³) ３ ) １／２ Examples include:

[0036] The above (meth)acrylic compound may contain an alkyl (meth)acrylate having an alkyl group having 11 or fewer carbon atoms. Furthermore, the above acrylic compound may contain an alkyl (meth)acrylate having an alkyl group having 11 or fewer carbon atoms as the above (meth)acrylic compound (a).

[0037] Examples of alkyl (meth)acrylate esters having an alkyl group with 11 or fewer carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, n-hexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, 1-methylheptyl (meth)acrylate, isooctyl (meth)acrylate, and n-nonyl (meth)acrylate. In particular, from the viewpoint of enabling the adhesive layer to exhibit adhesive strength to various materials and further improving the handling of the adhesive tape of this embodiment, it is preferable that the acrylic compound contains an alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms. Furthermore, from the viewpoint of enabling the adhesive tape of this embodiment to maintain shock absorption while providing excellent deformation resistance (especially bending resistance), it is preferable that the acrylic compound contains an alkyl (meth)acrylate having a linear or branched alkyl group having 6 to 8 carbon atoms.

[0038] When the above acrylic copolymer contains structural units derived from an alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms, it is preferable that the content of structural units derived from the alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms in the acrylic copolymer is 30% by mass or more and less than 100% by mass. By having a content of structural units derived from the alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms within the above range, the adhesive layer can increase its adhesive strength to various materials, and the handling of the adhesive tape of this embodiment is further improved. A more preferable lower limit for the content of structural units derived from the alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms is 40% by mass, a more preferable upper limit is 80% by mass, an even more preferable lower limit is 50% by mass, and an even more preferable upper limit is 70% by mass.

[0039] When the above acrylic copolymer contains structural units derived from an alkyl (meth)acrylate ester having a linear or branched alkyl group having 6 to 8 carbon atoms, the preferred lower limit of the content of structural units derived from the alkyl (meth)acrylate ester having a linear or branched alkyl group having 6 to 8 carbon atoms in the above acrylic copolymer is 10% by mass, and the preferred upper limit is 80% by mass. By having the content of structural units derived from the alkyl (meth)acrylate ester having a linear or branched alkyl group having 6 to 8 carbon atoms within the above range, the adhesive tape of this embodiment is more likely to be given excellent deformation resistance (especially bending resistance) while maintaining shock absorption. A more preferred lower limit of the content of structural units derived from the alkyl (meth)acrylate ester having a linear or branched alkyl group having 6 to 8 carbon atoms is 20% by mass, a more preferred upper limit is 60% by mass, an even more preferred lower limit is 30% by mass, and an even more preferred upper limit is 50% by mass. Examples of the content of constituent units derived from alkyl (meth)acrylate having linear or branched alkyl groups with 6 to 8 carbon atoms include 10% to 80% by mass, 20% to 65% by mass, 30% to 50% by mass, and so on.

[0040] The (meth)acrylic compound may also contain an alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure. By including a structural unit derived from the alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure as a structural unit derived from the (meth)acrylic compound, it becomes easier to impart excellent deformation resistance (especially bending resistance) to the adhesive tape of this embodiment. Furthermore, the (meth)acrylic compound may also contain an alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure as the (meth)acrylic compound (a).

[0041] Examples of constituent units derived from alkyl (meth)acrylate esters having an aliphatic cyclic structure include cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, which are derived from alkyl (meth)acrylate esters having an aliphatic cyclic structure.

[0042] When the above acrylic copolymer contains structural units derived from an alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure, the preferred lower limit of the content of structural units derived from the alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure in the acrylic copolymer is 3% by mass, and the preferred upper limit is 50% by mass. By having the content of structural units derived from the alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure within the above range, the adhesive tape of this embodiment is more likely to maintain shock absorption while providing excellent deformation resistance (especially bending resistance). A more preferred lower limit of the content of structural units derived from the alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure is 5% by mass, a more preferred upper limit is 40% by mass, an even more preferred lower limit is 7% by mass, and an even more preferred upper limit is 30% by mass. Examples of the content of structural units derived from the alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure include 3% by mass or more and 50% by mass or less, 5% by mass or more and 40% by mass or less, and 7% by mass or more and 30% by mass or less.

[0043] The (meth)acrylic compound preferably contains a monomer having a crosslinkable functional group. Because the acrylic copolymer has structural units derived from the (meth)acrylic compound, as well as structural units derived from the monomer having a crosslinkable functional group, the acrylic copolymer can sufficiently form a crosslinked structure through chemical crosslinking via a crosslinking agent between molecules. Furthermore, because the polar functional groups in the acrylic copolymer interact with each other, the cohesive force of the adhesive layer is increased. As a result, the adhesive layer has a more appropriate hardness, making it easier to impart excellent deformation resistance (especially bending resistance) to the adhesive tape of this embodiment. Also, the (meth)acrylic compound may contain a monomer having a crosslinkable functional group as (meth)acrylic compound (a).

[0044] Examples of monomers having the above-mentioned crosslinkable functional group include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, and amino group-containing monomers. In particular, from the viewpoint of further increasing the cohesive force of the adhesive layer, it is preferable that the monomer having the above-mentioned crosslinkable functional group includes at least one selected from the group consisting of carboxyl group-containing monomers and hydroxyl group-containing monomers.

[0045] Examples of the above carboxyl group-containing monomers include unsaturated monocarboxylic acids such as (meth)acrylic acid, (meth)acryloylacetic acid, (meth)acryloylpropionic acid, (meth)acryloylbutyric acid, (meth)acryloylpentanoic acid, and crotonic acid, as well as dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, and itaconic acid. Examples of the above hydroxyl group-containing monomers include 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate. Examples of the above amide group-containing monomers include N-vinyl-2-pyrrolidone, N,N-dimethyl(meth)acrylamide, and N-isopropyl(meth)acrylamide. Examples of the above amino group-containing monomers include (meth)acryloylmorpholine, dimethylaminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate.

[0046] In the above acrylic copolymer, the preferred lower limit for the content of constituent units derived from the monomer having the crosslinkable functional group is 0.1% by mass, and the preferred upper limit is 10% by mass. When the content of constituent units derived from the monomer having the crosslinkable functional group is 0.1% by mass or more, the cohesive force of the adhesive layer is further increased, and the adhesive layer has a more appropriate hardness, making it easier to impart excellent deformation resistance (especially bending resistance) to the adhesive tape of this embodiment. When the content of constituent units derived from the monomer having the crosslinkable functional group is 10% by mass or less, the adhesive layer has an appropriate flexibility, and the shock absorption of the adhesive tape of this embodiment is further improved. A more preferred lower limit for the content of constituent units derived from the monomer having the crosslinkable functional group is 1.0% by mass, a more preferred upper limit is 9.0% by mass, an even more preferred lower limit is 3.0% by mass, an even more preferred upper limit is 8.0% by mass, an even more preferred lower limit is 5.0% by mass, and an even more preferred upper limit is 7.0% by mass. Examples of the content ratio of constituent units derived from the above polar functional group-containing monomers include 0.1% by mass or more and 10% by mass or less, 1.0% by mass or more and 9.0% by mass or less, 3.0% by mass or more and 8.0% by mass or less, and 5.0% by mass or more and 7.0% by mass or less.

[0047] In recent years, the depletion of petroleum resources and the emission of carbon dioxide from the combustion of petroleum-derived products have become serious concerns. Therefore, attempts are being made to conserve petroleum resources by using bio-derived materials instead of petroleum-derived materials. For this reason, the (meth)acrylic compound in the constituent unit derived from the (meth)acrylic compound described above may consist only of petroleum-derived materials, but it is preferable that it also contains bio-derived materials that include bio-derived carbon. The inclusion of bio-derived materials in the (meth)acrylic compound is preferable from the standpoint of conserving petroleum resources, and furthermore, since bio-derived materials are originally produced by taking in carbon dioxide from the atmosphere, it is thought that burning them will not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the standpoint of reducing carbon dioxide emissions.

[0048] When the (meth)acrylic compound in the constituent unit derived from the above-mentioned (meth)acrylic compound contains a bio-derived material, examples of (meth)acrylic compounds containing a bio-derived material include alkyl (meth)acrylates synthesized by esterification of an alcohol, which is a bio-derived material, with (meth)acrylic acid.

[0049] The above acrylic copolymer may have structural units other than those derived from the above (meth)acrylic compound.

[0050] The above-mentioned acrylic copolymer preferably has constituent units derived from a vinyl aromatic compound as constituent units other than those derived from the above-mentioned (meth)acrylic compound. By having constituent units derived from a vinyl aromatic compound in the above-mentioned acrylic copolymer, the adhesive tape of this embodiment exhibits superior shock absorption.

[0051] Examples of constituent units derived from the vinyl aromatic compounds mentioned above include constituent units derived from styrene, constituent units derived from α-methylstyrene, and constituent units derived from their hydrogenated products. Among these, constituent units derived from styrene are preferred from the viewpoint of achieving both shock absorption and bending resistance in the resulting adhesive tape. Note that the constituent units derived from these vinyl aromatic compounds may consist of only one type, or two or more types may coexist.

[0052] When the above acrylic copolymer has structural units derived from a vinyl aromatic compound, the above acrylic copolymer may be a random copolymer, or it may be a block copolymer (hereinafter sometimes simply referred to as "block copolymer (A)") of a soft block (hereinafter sometimes simply referred to as "soft block") having structural units derived from the above hydrocarbon group (meth)acrylic acid ester) and a hard block (hereinafter sometimes simply referred to as "hard block") having structural units derived from the above vinyl aromatic compound. In particular, from the viewpoint of the resulting adhesive tape having superior shock absorption properties, it is preferable that the above acrylic copolymer includes block copolymer (A) when it has structural units derived from a vinyl aromatic compound.

[0053] The block copolymer (A) described above may be a diblock copolymer or a triblock copolymer. Among these, a triblock copolymer is preferred from the viewpoint of achieving both shock absorption and bending resistance of the resulting adhesive tape, and among triblock copolymers, a triblock copolymer having the hard block-soft block-hard block structure described above is more preferred.

[0054] In the above acrylic copolymer, the preferred lower limit for the content of constituent units derived from the vinyl aromatic compound is 2.5% by mass, and the preferred upper limit for the content of constituent units derived from the vinyl aromatic compound is 15% by mass. By having the content of constituent units derived from the vinyl aromatic compound within the above range, the adhesive tape of this embodiment is more likely to be given better deformation resistance (especially bending resistance) while maintaining better shock absorption. A more preferred lower limit for the content of constituent units derived from the vinyl aromatic compound is 3.5% by mass, a more preferred upper limit is 12% by mass, an even more preferred lower limit is 4.5% by mass, an even more preferred upper limit is 10% by mass, an even more preferred lower limit is 6.0% by mass, and an even more preferred upper limit is 8.0% by mass. Examples of the content of constituent units derived from the vinyl aromatic compound include 2.5% by mass or more and 15% by mass or less, 3.5% by mass or more and 12% by mass or less, 4.5% by mass or more and 10% by mass or less, 6.0% by mass or more and 8.0% by mass or less.

[0055] The weight-average molecular weight (Mw) of the above acrylic copolymer has a preferred lower limit of 300,000 and a preferred upper limit of 1,500,000. By having the weight-average molecular weight (Mw) of the above acrylic copolymer within this range, the cohesive force of the adhesive layer is further increased, allowing the adhesive tape of this embodiment to be given superior deformation resistance (especially bending resistance). A more preferred lower limit for the weight-average molecular weight (Mw) of the above acrylic copolymer is 500,000, a more preferred upper limit is 1,200,000, an even more preferred lower limit is 800,000, and an even more preferred upper limit is 1,000,000. Examples of weight-average molecular weight (Mw) of the above acrylic copolymer include 300,000 to 1,500,000, 500,000 to 1,200,000, and 800,000 to 1,000,000.

[0056] The polydispersity (weight-average molecular weight / number-average molecular weight, Mw / Mn) of the above acrylic copolymer has a preferred lower limit of 1.0 and a preferred upper limit of 8.0. When the polydispersity (Mw / Mn) of the above acrylic copolymer is within the above range, the cohesive force of the adhesive layer is further increased, and the adhesive tape of this embodiment can be given superior deformation resistance (especially bending resistance). A more preferred lower limit for the polydispersity (Mw / Mn) of the above acrylic copolymer is 1.5, and a more preferred upper limit is 7.5. Examples of polydispersity (Mw / Mn) of the above acrylic copolymer include 1.0 to 8.0 and 1.5 to 7.5.

[0057] The weight-average molecular weight and number-average molecular weight of the above-mentioned acrylic copolymer can be measured by the following method. Specifically, the acrylic copolymer is diluted 50 times with an organic solvent such as ethyl acetate, and the resulting diluted solution is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare a measurement sample. Next, this measurement sample is supplied to a gel permeation chromatograph, and GPC measurement is performed under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of the acrylic copolymer is measured, and the obtained values ​​are taken as the weight-average molecular weight and number-average molecular weight. Examples of gel permeation chromatographs include the 2690 Separations Module (manufactured by Waters), and examples of columns include the GPC KF-806L (manufactured by Showa Denko).

[0058] Methods for adjusting the weight-average molecular weight of the above-mentioned acrylic copolymer include, for example, changing the type and amount of polymerization initiator and monomer concentration during the polymerization reaction, adding a small amount of chain transfer agent such as dodecyl mercaptan, controlling chain transfer to the solvent by changing the type of polymerization reaction solvent, and changing the temperature and time during polymerization.

[0059] The preferred lower limit of the glass transition temperature (Tg) of the above acrylic copolymer is -60°C, and the preferred upper limit is 20°C. A glass transition temperature (Tg) of the above acrylic copolymer of -60°C or higher increases the cohesive force of the adhesive layer, thereby providing the adhesive tape of this embodiment with superior bending resistance. A glass transition temperature (Tg) of the above acrylic copolymer of 20°C or lower further improves the shock absorption of the adhesive tape of this embodiment. A more preferred lower limit of the glass transition temperature (Tg) of the above acrylic copolymer is -40°C, a more preferred upper limit is 0°C, an even more preferred lower limit is -30°C, and an even more preferred upper limit is -10°C. Examples of glass transition temperatures (Tg) for the above acrylic copolymer include -60°C to 20°C, -40°C to 0°C, and -30°C to -10°C.

[0060] The glass transition temperature (Tg) of the above acrylic copolymer can be determined by differential scanning calorimetry. More specifically, it can be measured under a nitrogen atmosphere (nitrogen flow, flow rate 50 mL / min), in accordance with JIS K 6240:2011, with a measurement temperature of -100°C to 200°C and a heating rate of 10°C / min.

[0061] One method for adjusting the glass transition temperature (Tg) of the above-mentioned acrylic copolymer is to adjust the type and content of the constituent monomers of the acrylic copolymer.

[0062] The preferred lower limit for the content of the acrylic copolymer in the adhesive layer is 50% by mass, and the preferred upper limit is 99.5% by mass. By having the content of the acrylic copolymer within the above range, the adhesive tape of this embodiment will have better shock absorption properties. A more preferred lower limit for the content of the acrylic copolymer is 60% by mass, a more preferred upper limit is 90% by mass, an even more preferred lower limit is 65% by mass, and an even more preferred upper limit is 85% by mass. Examples of the content of the acrylic copolymer include 50% by mass or more and 99.5% by mass or less, 60% by mass or more and 90% by mass or less, 65% by mass or more and 85% by mass or less, etc.

[0063] As polymerization methods for synthesizing the above-mentioned acrylic copolymer, conventionally known methods can be used in which a mixture of constituent monomers that serve as raw materials undergoes a radical reaction in the presence of a polymerization initiator. Examples include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, solution polymerization is preferred because it is easy to synthesize.

[0064] When solution polymerization is used as the polymerization method described above, examples of reaction solvents include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, and diethyl ether. These reaction solvents may be used individually or in combination of two or more.

[0065] Examples of polymerization initiators include organic peroxides and azo compounds. Examples of organic peroxides include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonilonitrile. These polymerization initiators may be used alone or in combination of two or more.

[0066] Furthermore, even when the acrylic copolymer is the block copolymer (A), the method for producing the block copolymer (A) is not particularly limited, and conventionally known methods can be used. Specifically, for example, a vinyl aromatic compound may be added to the soft block synthesized in the same manner as the acrylic copolymer described above, and copolymerized. Alternatively, the hard block and soft block synthesized in advance may be copolymerized.

[0067] Furthermore, if the block copolymer is a triblock copolymer having the structure of the hard block - soft block - hard block, the block copolymer can be obtained, for example, by living polymerization. Examples of living polymerization include living anionic polymerization and RAFT polymerization, but RAFT polymerization is particularly preferred. When producing the block copolymer (A) having the hard block - soft block - hard block by RAFT polymerization, the hard block is obtained using a chain transfer agent (RAFT agent), and then the constituent unit monomers of the soft block are polymerized or copolymerized in the presence of the obtained hard block to produce the triblock copolymer.

[0068] The adhesive layer preferably contains at least one elastomer selected from styrene-based elastomers, olefin-based elastomers, and urethane-based elastomers (hereinafter sometimes referred to as "elastomer (E1)"). By containing at least one elastomer selected from styrene-based elastomers, olefin-based elastomers, and urethane-based elastomers in the adhesive layer, the adhesive tape of this embodiment becomes superior in shock absorption. Among these, styrene-based elastomers are preferred from the viewpoint of their excellent compatibility with the acrylic copolymer and their low glass transition temperature, which further improves the shock absorption of the adhesive tape of this embodiment.

[0069] Preferably, the above styrene-based elastomer contains an aromatic block copolymer (X) having at least two blocks having structural units derived from vinyl aromatic compounds (hereinafter sometimes simply referred to as "vinyl aromatic polymer blocks"), and at least one of a block having structural units derived from a conjugated diene compound (hereinafter sometimes simply referred to as "conjugated diene polymer blocks") and a hydrogenated product of a block having structural units derived from a conjugated diene compound (hereinafter sometimes simply referred to as "hydrogenated product of conjugated diene polymer blocks"). In the above aromatic block copolymer (X), the vinyl aromatic polymer blocks act as hard segment portions, and the conjugated diene polymer blocks and the hydrogenated product of the conjugated diene polymer blocks act as soft segment portions, imparting rubber elasticity to the adhesive layer. Therefore, by containing the above aromatic block copolymer (X) in the styrene-based elastomer, the adhesive tape of this embodiment has superior shock absorption properties.

[0070] The vinyl aromatic polymer block described above may be any block having 5% by mass or more of constituent units derived from a vinyl aromatic compound, and may also contain constituent units derived from other compounds such as ethylene and 1,3-butadiene (which is converted to an ethylene-butylene structure by hydrogenation). Examples of the vinyl aromatic compound in the vinyl aromatic polymer block include alkylstyrene, halogenated styrene, halogen-substituted alkylstyrene, alkoxystyrene, carboxyalkylstyrene, alkyl ether styrene, alkylsilyl styrene, vinyl benzyl dimethoxy phosphide, vinyl naphthalene, vinyl anthracene, N,N-diethyl-p-aminoethylstyrene, and vinylpyridine.

[0071] Examples of alkylstyrenes include styrene, methylstyrene, dimethylstyrene, and t-butylstyrene. Examples of halogenated styrenes include chlorostyrene, bromostyrene, and fluorostyrene. Examples of halogen-substituted alkylstyrenes include chloromethylstyrene. Examples of alkoxystyrenes include methoxystyrene and ethoxystyrene. Examples of carboxyalkylstyrenes include carboxymethylstyrene. Examples of alkyl ether styrenes include vinyl benzyl propyl ether. Examples of alkylsilyl styrenes include trimethylsilyl styrene. Among these, styrene, methylstyrene, and dimethylstyrene are preferred, and styrene is more preferred because it is readily available industrially. These vinyl aromatic compounds may be used individually or in combination of two or more.

[0072] The preferred lower limit for the content of constituent units derived from the vinyl aromatic compound in the vinyl aromatic polymer block is 7% by mass. A content of 7% by mass or more of constituent units derived from the vinyl aromatic compound further improves the bending rigidity of the adhesive layer, resulting in an adhesive tape with excellent shock absorption and superior bending resistance. A more preferred lower limit for the constituent units derived from the vinyl aromatic compound is 10% by mass. Furthermore, from the viewpoint of further improving the flexibility of the adhesive layer and resulting in an adhesive tape with superior shock absorption, a preferred upper limit for the constituent units derived from the vinyl aromatic compound is 35% by mass. Examples of the content of constituent units derived from the vinyl aromatic compound in the vinyl aromatic polymer block include 7% by mass or more and 35% by mass or less, and 10% by mass or more and 35% by mass or less.

[0073] Examples of the above-mentioned conjugated diene compounds include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-octadiene, 1,3-hexadiene, 1,3-cyclohexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, myrcene, and chloroprene. In addition to the above-mentioned conjugated diene compounds, other usable compounds include, for example, 2,5-dihydrofuran-2,5-dione. Among these, 1,3-butadiene and isoprene are preferred due to their high polymerization reactivity and ease of industrial availability. These conjugated diene compounds may be used individually or in combination of two or more.

[0074] The hydrogenated form of the above-mentioned conjugated diene polymer block refers to a block in which the carbon-carbon double bonds (unsaturated bonds) in the constituent units derived from the above-mentioned conjugated diene compound are converted to saturated bonds by hydrogenation. From the viewpoint of preventing degradation due to heat, ultraviolet rays, etc., it is preferable that 80% or more of the carbon-carbon double bonds (unsaturated bonds) in the constituent units derived from the above-mentioned conjugated diene compound of the aromatic block copolymer (X) are converted to saturated bonds by hydrogenation, more preferably 90% or more, even more preferably 95% or more, and even more preferably 96% or more. Furthermore, it is most preferable that 100% of the unsaturated bonds are converted to saturated bonds by hydrogenation (i.e., it is a fully hydrogenated form). That is, it is preferable that 80% to 100% of the carbon-carbon double bonds (unsaturated bonds) in the constituent units derived from the above-mentioned conjugated diene compound are converted to saturated bonds by hydrogenation, more preferably 90% to 100%, even more preferably 95% to 100%, and even more preferably 96% to 100%.

[0075] The preferred lower limit for the content of constituent units derived from the conjugated diene compound in the above-mentioned conjugated diene polymer block is 80% by mass. When the content of constituent units derived from the conjugated diene compound is 80% by mass or more, the flexibility of the adhesive layer is further improved, and the shock absorption of the resulting adhesive tape is further improved. In addition, the adhesive strength of the adhesive layer is further improved. A more preferred lower limit for the content of constituent units derived from the conjugated diene compound is 90% by mass, and an even more preferred lower limit is 95% by mass. Furthermore, there is no particular upper limit for the content of constituent units derived from the conjugated diene compound, and it may be 100% by mass. Examples of the content of constituent units derived from the conjugated diene compound in the above-mentioned conjugated diene polymer block include 80% by mass or more and 100% by mass or less, 90% by mass or more and 100% by mass or less, 95% by mass or more and 100% by mass or less, etc.

[0076] Examples of the structure of the above aromatic block copolymer (X) include, when the vinyl aromatic polymer block is B and the hydrogenated product of the block having constituent units derived from the conjugated diene polymer block and the conjugated diene compound is C, a triblock copolymer represented by formula B-C-B, a diblock copolymer represented by formula B-C, a pentablock copolymer represented by formula C-B-C-B-C, and the like.

[0077] Examples of aromatic block copolymers (X) having the structure represented by the above formula B-C-B include styrene-isoprene-styrene (SIS) block copolymer, styrene-butylene-styrene (SBS) block copolymer, styrene-ethylene-butylene-styrene (SEBS) block copolymer, styrene-ethylene-propylene-styrene (SEPS) block copolymer, styrene-ethylene-ethylene-propylene-styrene (SEEPS) block copolymer, styrene-isobutylene-styrene (SIBS) block copolymer, and ethylene-styrene-butylene block copolymer. Among these, SIS block copolymer and SEBS block copolymer are preferred from the viewpoint of compatibility with the above acrylic copolymer.

[0078] The preferred lower limit for the weight-average molecular weight (Mw) of the aromatic block copolymer (X) is 50,000. A weight-average molecular weight (Mw) of 50,000 or more results in a more shock-absorbing adhesive tape. A more preferred lower limit for the weight-average molecular weight of the aromatic block copolymer (X) is 100,000, and an even more preferred lower limit is 150,000. While there is no particular upper limit for the weight-average molecular weight of the aromatic block copolymer (X), a preferred upper limit is 500,000 from the viewpoint of compatibility with the acrylic copolymer. Examples of weight-average molecular weight (Mw) for the aromatic block copolymer (X) include 50,000 to 500,000, 100,000 to 500,000, and 150,000 to 500,000.

[0079] The above-mentioned olefin-based elastomer is an elastomer composed of olefin compounds, and is typically composed of a crystalline olefin block and an amorphous olefin block. In the above-mentioned olefin-based elastomer, the crystalline olefin block acts as a hard segment portion, and the amorphous olefin block acts as a soft segment portion, thereby imparting rubber elasticity to the adhesive layer.

[0080] Examples of crystalline olefins include ethylene and propylene.

[0081] Examples of amorphous olefins include isobutylene.

[0082] The above-mentioned urethane-based elastomer is an elastomer composed of a urethane compound obtained by the reaction of a polyol compound and a polyisocyanate compound. In this urethane-based elastomer, the urethane bond sites and urea bond sites act as hard segments, and the polyol chains act as soft segments, thereby imparting rubber elasticity to the adhesive layer.

[0083] Examples of the polyol compounds mentioned above include polyester polyols (polycondensates of divalent alcohols and divalent basic acids such as adipic acid, azelaic acid, and sepatic acid), polyether polyols (obtained by addition polymerization of ethylene oxide, tetrahydrofuran, etc.), polyacrylate polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols or their hydrogenated products, polyisoprene polyols or their hydrogenated products, phenolic polyols, epoxy polyols, caprolactone polyols, and polysulfone polyols. Copolymer polyols such as polyester-polyether polyols can also be cited as polyol compounds.

[0084] Examples of the polyisocyanate compounds mentioned above include diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, norbornane diisocyanate, transcyclohexane-1,4-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate, bis(isocyanate-methyl)cyclohexane, and dicyclohexylmethane diisocyanate. Alternatively, modified forms of the polyisocyanate compounds mentioned above may be used as the polyisocyanate compounds. Examples of modified polyisocyanate compounds include the bilate modified polyisocyanate compounds mentioned above, the isocyanurate modified polyisocyanate compounds mentioned above, adduct compounds obtained by reacting the polyisocyanate compounds mentioned above with glycerin, trimethylolpropane, or polyols obtained by addition polymerization of these with alkylene oxides such as propylene oxide and ethylene oxide, and polymethylene polyphenyl polyisocyanate, also known as polymeric MDI.

[0085] A preferred upper limit for the content of the elastomer (E1) per 100 parts by mass of the acrylic copolymer is 60 parts by mass. By having an elastomer (E1) content within this range, it becomes easier to impart better deformation resistance (especially bending resistance) to the adhesive tape of this embodiment while maintaining its shock absorption properties. A more preferred upper limit for the elastomer (E1) content is 55 parts by mass, and an even more preferred upper limit is 50 parts by mass. Furthermore, a preferred lower limit for the elastomer (E1) content is 10 parts by mass. Having an elastomer (E1) content of 10 parts by mass or more further improves the flexibility of the adhesive layer, resulting in an adhesive tape with superior shock absorption. A more preferred lower limit for the elastomer (E1) content is 15 parts by mass, an even more preferred lower limit is 20 parts by mass, and an even more preferred lower limit is 30 parts by mass. Examples of the elastomer (E1) content include 10 parts by mass or more and 60 parts by mass or less, 15 parts by mass or more and 55 parts by mass or less, 20 parts by mass or more and 50 parts by mass or less, 30 parts by mass or more and 50 parts by mass or less, etc.

[0086] The adhesive layer described above may or may not contain a tackifying resin. By including a tackifying resin in the adhesive layer, the adhesive tape of this embodiment can be given superior deformation resistance (especially bending resistance). On the other hand, by not including a tackifying resin in the adhesive layer, the shock absorption of the adhesive tape of this embodiment is further improved.

[0087] Examples of the tackifying resins mentioned above include rosin resins, rosin ester resins, hydrogenated rosin resins, terpene resins, terpene phenol resins, coumarone indene resins, alicyclic saturated hydrocarbon resins, C5 petroleum resins, C9 petroleum resins, and C5-C9 copolymer petroleum resins. Among these, rosin ester resins or terpene phenol resins are preferred from the viewpoint of compatibility with the acrylic copolymer, and among these, rosin ester resins or terpene phenol resins having hydroxyl groups are more preferred from the viewpoint of further increasing the cohesive force of the adhesive layer and providing the adhesive tape of this embodiment with excellent deformation resistance (especially bending resistance). These tackifying resins may be used alone or in combination of two or more types.

[0088] Examples of rosin ester resins having the hydroxyl group mentioned above include Pencel D-135 and Super Ester A-75 (both manufactured by Arakawa Chemical Industries, Ltd.). Examples of terpene phenol resins include YS Polystar G150 and YS Polystar T160 (both manufactured by Yasuhara Chemical Co., Ltd.).

[0089] If the adhesive layer contains the tackifying resin, it is preferable that the tackifying resin contains bio-derived carbon. By including a bio-derived carbon in the tackifying resin, the content of bio-derived carbon in the adhesive layer described later can be increased, and the environmental burden of the adhesive tape of this embodiment can be further reduced. Specific examples of bio-derived carbon-containing tackifying resins include Pine Crystal KE-604, Pine Crystal KR-140 (all rosin-based resins, manufactured by Arakawa Chemical Industries), Pine Crystal KE-100, Pine Crystal KE-359, Super Ester A-75 (all rosin ester-based resins, manufactured by Arakawa Chemical Industries), and Tamanol 803L (terpene phenol-based resin, manufactured by Arakawa Chemical Industries).

[0090] If the adhesive layer contains the tackifying resin, it is preferable that the tackifying resin has a softening point of 70°C or higher and 170°C or lower. By including a tackifying resin with a softening point of 70°C or higher, the glass transition temperature of the adhesive layer is increased, and the adhesive tape of this embodiment can be given superior deformation resistance (especially bending resistance). By including a tackifying resin with a softening point of 170°C or lower, the adhesive layer does not become too hard, and the shock absorption of the adhesive tape of this embodiment is further improved. It is more preferable that the tackifying resin includes a tackifying resin with a softening point of 120°C or higher and 150°C or lower, and even more preferable that it includes a tackifying resin with a softening point of 130°C or higher and 140°C or lower. In this specification, "softening point of tackifying resin" means the softening temperature measured by JIS K 2207 (ring-sphere method).

[0091] If the adhesive layer contains the tackifying resin, it is preferable that the tackifying resin has a hydroxyl value of 25 mg KOH / g or more. By including a tackifying resin with a hydroxyl value of 25 mg KOH / g or more, the cohesive force of the adhesive layer is further increased, and the adhesive tape of this embodiment can be given superior deformation resistance (especially bending resistance). It is more preferable that the tackifying resin includes a tackifying resin with a hydroxyl value of 30 mg KOH / g or more, and even more preferable that it includes a tackifying resin with a hydroxyl value of 35 mg KOH / g or more. There is no particular upper limit to the hydroxyl value of the tackifying resin, but from the viewpoint of compatibility with the aromatic block copolymer (X), a preferred upper limit is 50 mg KOH / g. Examples of the hydroxyl value of the tackifying resin include 25 mg KOH / g to 50 mg KOH / g, 30 mg KOH / g to 50 mg KOH / g, 35 mg KOH / g to 50 mg KOH / g, etc. Furthermore, in this specification, the hydroxyl value of the tackifying resin can be measured by JIS K1557 (phthalic anhydride method).

[0092] When the adhesive layer contains the tackifying resin, the preferred upper limit of the tackifying resin content is 50 parts by mass per 100 parts by mass of the acrylic copolymer. A tackifying resin content of 50 parts by mass or less prevents the adhesive layer from becoming too hard, further improving the shock absorption of the adhesive tape of this embodiment. A more preferred upper limit for the tackifying resin content is 40 parts by mass, an even more preferred upper limit is 30 parts by mass, an even more preferred upper limit is 20 parts by mass, and a particularly preferred upper limit is 10 parts by mass. Furthermore, when the adhesive layer contains the tackifying resin, the glass transition temperature of the adhesive layer increases, and from the viewpoint of providing the adhesive tape of this embodiment with superior deformation resistance (especially bending resistance), a preferred lower limit for the tackifying resin content is 0.1 parts by mass, and a more preferred lower limit is 1.0 part by mass. Furthermore, if the adhesive layer contains the tackifying resin, the content of the tackifying resin can be, for example, 0.1 parts by mass or more and 50 parts by mass or less, 1.0 part by mass or more and 40 parts by mass or less, 1.0 part by mass or more and 30 parts by mass or less, 1.0 part by mass or more and 20 parts by mass or less, 1.0 part by mass or more and 10 parts by mass or less, etc. In addition, the adhesive layer does not have to contain the tackifying resin, and from the viewpoint of further improving the shock absorption of the resulting adhesive tape, it is preferable that the adhesive layer does not contain the tackifying resin.

[0093] The adhesive layer may be colored. If the adhesive layer is colored, light-shielding properties can be imparted to the adhesive layer, thereby suppressing deterioration of the adherend to the adhesive tape of this embodiment due to light and ultraviolet rays. Therefore, the adhesive tape of this embodiment can be more suitably used for fixing electronic equipment components or automotive components.

[0094] If the adhesive layer is colored, it is preferable that the adhesive layer contains a coloring agent. Examples of the coloring agent include pigments and dyes. Among these, pigments are preferred because they have excellent heat resistance and the resulting adhesive tape can be more suitably used for fixing electronic equipment components or automotive components. Examples of the pigments include carbon black, aniline black, and titanium dioxide. Among these, carbon black is preferred because it is relatively inexpensive and chemically stable. Examples of the dyes include azo dyes, anthraquinone dyes, and phthalocyanine dyes.

[0095] The preferred upper limit of the coloring agent content per 100 parts by mass of the acrylic copolymer is 5.0 parts by mass. A coloring agent content of 5.0 parts by mass or less provides sufficient adhesion to the adhesive layer. A more preferred upper limit for the coloring agent content is 4.0 parts by mass, an even more preferred upper limit is 3.5 parts by mass, and an even more preferred upper limit is 2.0 parts by mass. Furthermore, if the adhesive layer contains a coloring agent, the preferred lower limit is 0.2 parts by mass. A coloring agent content of 0.2 parts by mass or more provides sufficient light-shielding properties to the adhesive layer. A more preferred lower limit for the coloring agent content is 0.5 parts by mass, an even more preferred lower limit is 0.8 parts by mass, and an even more preferred lower limit is 1.0 part by mass. Furthermore, if the adhesive layer contains the coloring agent, the amount of coloring agent can be, for example, 0.2 parts by mass or more and 5.0 parts by mass or less, 0.5 parts by mass or more and 4.0 parts by mass or less, 0.8 parts by mass or more and 3.5 parts by mass or less, 1.0 part by mass or more and 2.0 parts by mass or less, etc. Also, the adhesive layer does not have to contain a coloring agent, and from the viewpoint of further improving the shock absorption of the resulting adhesive tape, it is preferable that the adhesive layer does not contain a coloring agent.

[0096] Preferably, the adhesive layer has a structure derived from a crosslinking agent. Because the adhesive layer has a structure derived from a crosslinking agent, its cohesive force is increased, allowing the adhesive tape of this embodiment to exhibit superior deformation resistance (especially bending resistance). A method for providing the adhesive layer with a structure derived from a crosslinking agent includes, for example, applying an adhesive composition containing a crosslinking agent to a release film or the like, and then heating and drying it.

[0097] The above adhesive composition preferably contains a crosslinking agent. The inclusion of a crosslinking agent in the adhesive composition makes it easier to create an adhesive layer with a structure derived from the crosslinking agent. Therefore, the adhesive layer has increased cohesive strength, resulting in the adhesive tape of this embodiment exhibiting superior deformation resistance (particularly bending resistance). From the viewpoint of storage stability of the adhesive composition, the crosslinking agent may be added to the adhesive composition immediately before forming the adhesive layer.

[0098] Examples of the crosslinking agents include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents. Among these, isocyanate-based crosslinking agents are preferred from the viewpoint of further improving the cohesive strength of the adhesive layer.

[0099] The preferred lower limit of the crosslinking agent content per 100 parts by mass of the acrylic copolymer is 0.05 parts by mass, and the preferred upper limit is 5.0 parts by mass. By having the crosslinking agent content within the above range, the degree of crosslinking of the adhesive layer is appropriately adjusted, and the balance between the bending rigidity and stress relaxation properties of the adhesive layer is improved, so that the resulting adhesive tape maintains excellent shock absorption while easily being given better deformation resistance (especially bending resistance). A more preferred lower limit for the crosslinking agent content is 0.10 parts by mass, a more preferred upper limit is 3.0 parts by mass, an even more preferred lower limit is 0.15 parts by mass, an even more preferred upper limit is 2.0 parts by mass, an even more preferred upper limit is 1.0 part by mass, and a particularly preferred upper limit is 0.50 parts by mass. Examples of the crosslinking agent content include 0.05 parts by mass or more and 5.0 parts by mass or less, 0.10 parts by mass or more and 3.0 parts by mass or less, 0.15 parts by mass or more and 2.0 parts by mass or less, 0.15 parts by mass or more and 1.0 part by mass or less, 0.15 parts by mass or more and 0.50 parts by mass or less.

[0100] The adhesive layer described above may contain conventionally known additives such as antioxidants, organic fillers, inorganic fillers, surfactants, stabilizers, and softeners, as needed.

[0101] The adhesive layer described above has a preferred upper limit for its glass transition temperature of 40°C. A glass transition temperature of 40°C or lower allows the adhesive tape of this embodiment to have superior shock absorption. A more preferred upper limit for the glass transition temperature of the adhesive layer is 35°C, and an even more preferred upper limit is 25°C. Furthermore, a preferred lower limit for the glass transition temperature of the adhesive layer is 0°C. A glass transition temperature of 0°C or higher allows the adhesive tape of this embodiment to maintain excellent shock absorption while providing superior deformation resistance (especially bending resistance). A more preferred lower limit for the glass transition temperature of the adhesive layer is 5°C, and an even more preferred lower limit is 10°C. In this specification, "glass transition temperature of the adhesive layer" refers to the temperature at which a maximum of loss tangent (tanδ) obtained by dynamic viscoelasticity measurement occurs, specifically the maximum caused by micro-Brownian motion.

[0102] The glass transition temperature of the adhesive layer can be measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz. Specifically, a test specimen is prepared by laminating only the adhesive layer to a thickness of approximately 500 μm. Dynamic viscoelasticity measurements are then performed on the prepared test specimen using a dynamic viscoelasticity measuring device (for example, "DVA-200" manufactured by IT Measurement Control Co., Ltd.) under the conditions of simple heating mode, heating rate of 10°C / min, shear direction, frequency of 100 Hz, and temperature range from -50°C to 300°C. The glass transition temperature of the adhesive layer can then be obtained from the resulting dynamic viscoelastic spectrum.

[0103] Methods for adjusting the glass transition temperature of the adhesive layer include, for example, adjusting the composition, weight-average molecular weight, and polydispersity of the acrylic copolymer contained in the adhesive layer, and adjusting the type and content of the elastomer, tackifying resin, and crosslinking agent contained in the adhesive layer.

[0104] The preferred lower limit for the gel fraction of the adhesive layer is 10% by mass, and the preferred upper limit is 70% by mass. When the gel fraction of the adhesive layer is 10% by mass or more, the cohesive force of the adhesive layer is increased, thereby providing the adhesive tape of this embodiment with superior deformation resistance (especially bending resistance). When the gel fraction of the adhesive layer is 70% by mass or less, the flexibility of the adhesive layer is further improved, thereby improving the shock absorption of the resulting adhesive tape. A more preferred lower limit for the gel fraction of the adhesive layer is 20% by mass, a more preferred upper limit is 60% by mass, an even more preferred lower limit is 30% by mass, an even more preferred upper limit is 50% by mass, and an even more preferred lower limit is 40% by mass. Examples of the gel fraction of the adhesive layer include 10% by mass or more and 70% by mass or less, 20% by mass or more and 60% by mass or less, 30% by mass or more and 50% by mass or less, 40% by mass or more and 50% by mass or less, etc.

[0105] The gel fraction of the adhesive layer described above can be measured by the following method. Specifically, first, a test specimen is prepared by cutting the adhesive tape having the adhesive layer into a planar rectangular shape with a width of 20 mm and a length of 40 mm. The test specimen is immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The mass of the dried test specimen is measured, and the gel fraction is calculated using the following formula (I). Note that the test specimen does not have a release film laminated on it to protect the adhesive layer. Furthermore, if the adhesive tape of this embodiment is a non-support type adhesive tape without a base material, the measurement can be performed using a test specimen obtained by attaching it to a base material and then cutting it, or without using a base material, W in the following formula (I) can be calculated. ０ Calculate by setting to 0. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １ -W ０ ) (I) (W ０ : Mass of the base material, W １ : Mass of the test specimen before immersion, W ２ (Mass of the test specimen after immersion and drying)

[0106] Methods for adjusting the gel fraction of the adhesive layer include, for example, adjusting the type and content ratio of constituent units derived from monomers having crosslinkable functional groups contained in the acrylic copolymer in the adhesive layer; adjusting the type and content of crosslinking agents contained in the adhesive layer; and adjusting the irradiance and irradiation time of electron beams or ultraviolet rays used when electron beam irradiation or ultraviolet irradiation is performed to form the adhesive layer.

[0107] The preferred lower limit for the bio-derived carbon content in the adhesive layer is 10%. A bio-derived carbon content of 10% or more in the adhesive layer results in an adhesive tape that is superior in terms of conserving petroleum resources and reducing carbon dioxide emissions, thereby reducing environmental impact. A more preferred lower limit for the bio-derived carbon content in the adhesive layer is 15%, and an even more preferred lower limit is 20%. Furthermore, there is no particular upper limit for the bio-derived carbon content in the adhesive layer, and it may be 100%. Examples of bio-derived carbon content in the adhesive layer include 10% to 100%, 15% to 100%, and 20% to 100%.

[0108] While bio-derived carbon contains a certain percentage of the radioactive isotope C-14, petroleum-derived carbon contains almost no C-14. Therefore, the "biologically derived carbon content" as used herein can be calculated by measuring the concentration of C-14 contained in the adhesive layer. Specifically, it can be measured in accordance with ASTM D6866-24, a standard widely used in the bioplastics industry.

[0109] The content of bio-derived carbon in the adhesive layer can be adjusted by changing the composition of the adhesive layer. Specifically, examples include a method of synthesizing the acrylic copolymer using an alkyl (meth)acrylate containing bio-derived carbon or a monomer having a crosslinkable functional group containing bio-derived carbon, or a method of incorporating a tackifying resin containing bio-derived carbon into the adhesive layer.

[0110] The adhesive layer may have an open-cell structure or a closed-cell structure, but it is preferable to have a closed-cell structure. Having a closed-cell structure in the adhesive layer improves the bending rigidity of the adhesive layer, making it easier to impart superior deformation resistance (especially bending resistance) to the resulting adhesive tape. In addition, the increased tensile strength of the adhesive layer suppresses cohesive failure of the adhesive layer, thus improving the adhesive strength of the adhesive tape in this embodiment. The cell structure can be confirmed, for example, by observing it at a magnification of 150 to 200 times using an optical microscope (for example, Keyence's "VHX-6000").

[0111] The deemed density of the above adhesive layer has a preferred lower limit of 0.59 g / cm³. ３ Therefore, a preferred upper limit is 1.15 g / cm³. ３ Therefore, the balance between the bending rigidity and stress relaxation properties of the adhesive layer is improved, making it easier to impart superior deformation resistance (especially bending resistance) to the resulting adhesive tape while maintaining excellent shock absorption. A more preferable lower limit for the deemed density of the adhesive layer is 0.65 g / cm³. ３ A more preferable upper limit is 1.05 g / cm³. ３ A more preferable lower limit is 0.70 g / cm³. ３ A more preferable upper limit is 1.00 g / cm³. ３ A more preferable lower limit is 0.80 g / cm³. ３ A more preferable upper limit is 0.90 g / cm³. ３ The deemed density of the adhesive layer is, for example, 0.59 g / cm³. ３ 1.15g / cm or more ３ Below, 0.65g / cm ３ 1.05g / cm or more ３ Below, 0.70g / cm ３ 1.00g / cm or more ３ Below, 0.80g / cm ３ 0.90g / cm or more ３ The following are some examples.

[0112] The deemed density of the adhesive layer described above can be measured using an electronic hydrometer (for example, Mirage's "ED120T") in accordance with JIS K 7222 or similar standards.

[0113] Methods for adjusting the deemed density of the adhesive layer include, for example, adjusting the type and content of foaming agents such as foaming particles, and changing the composition of the adhesive layer.

[0114] The average major diameter of the bubbles in the adhesive layer described above has a preferred lower limit of 10 μm and a preferred upper limit of 80 μm. When the average major diameter of the bubbles in the adhesive layer is 10 μm or more, the stress relaxation properties of the adhesive layer are further improved, resulting in an adhesive tape with superior shock absorption. When the average major diameter of the bubbles in the adhesive layer is 80 μm or less, the bending rigidity of the adhesive layer is further improved, making it easier to impart superior deformation resistance (especially bending resistance) to the resulting adhesive tape. In addition, since the fracture strength of the adhesive layer is increased, cohesive failure of the adhesive layer can be further suppressed, thus improving the adhesive strength of the adhesive tape in this embodiment. A more preferred lower limit for the average major diameter of the bubbles in the adhesive layer is 15 μm, a more preferred upper limit is 70 μm, an even more preferred lower limit is 20 μm, an even more preferred upper limit is 65 μm, an even more preferred upper limit is 60 μm, a particularly preferred upper limit is 55 μm, and a very preferred upper limit is 50 μm. The average major diameter of the bubbles in the adhesive layer can be, for example, 10 μm to 80 μm, 15 μm to 70 μm, 20 μm to 65 μm, 20 μm to 60 μm, 20 μm to 55 μm, 20 μm to 50 μm, etc.

[0115] The average minor diameter of the bubbles in the adhesive layer has a preferred lower limit of 10 μm and a preferred upper limit of 75 μm. A more preferable lower limit for the average minor diameter of the bubbles in the adhesive layer is 10 μm or more, which further improves the stress relaxation properties of the adhesive layer, thus providing superior shock absorption to the resulting adhesive tape. A more preferable upper limit for the average minor diameter of the bubbles in the adhesive layer is 75 μm or less, which makes the adhesive layer less susceptible to cohesive failure and improves its adhesive strength, resulting in a more resilient adhesive tape. Furthermore, an increase in the tensile strength of the adhesive layer further suppresses cohesive failure, resulting in improved adhesive strength in the resulting adhesive tape. A more preferable lower limit for the average minor diameter of the bubbles in the adhesive layer is 15 μm, a more preferable upper limit is 70 μm, an even more preferable lower limit is 20 μm, an even more preferable upper limit is 65 μm, an even more preferable upper limit is 60 μm, a particularly preferable upper limit is 55 μm, and a very preferable upper limit is 50 μm. The average short diameter of the bubbles in the adhesive layer can be, for example, 10 μm to 75 μm, 15 μm to 70 μm, 20 μm to 65 μm, 20 μm to 60 μm, 20 μm to 55 μm, 20 μm to 50 μm, etc.

[0116] The aspect ratio of the bubbles in the adhesive layer described above has a preferred lower limit of 1.00 and a preferred upper limit of 3.50. When the aspect ratio of the bubbles in the adhesive layer described above is 1.00 or higher, the structure of the bubbles in the adhesive layer becomes flattened, and the stress relaxation properties of the adhesive layer are further improved, so that the resulting adhesive tape can be given superior shock absorption. When the aspect ratio of the bubbles in the adhesive layer described above is 3.50 or lower, the adhesive layer is less prone to cohesive failure and the adhesive strength is further improved, so the resulting adhesive tape has superior rebound resistance. A more preferred lower limit for the aspect ratio of the bubbles in the adhesive layer described above is 1.25, a more preferred upper limit is 3.00, an even more preferred lower limit is 1.50, and an even more preferred upper limit is 2.50. Examples of aspect ratios for the bubbles in the adhesive layer described above include 1.00 to 3.50, 1.25 to 3.00, 1.50 to 2.50, etc. Furthermore, in this specification, "bubble aspect ratio" means the value obtained by dividing the average major diameter of the bubble by the average minor diameter of the bubble (average major diameter of bubble / average minor diameter of bubble).

[0117] The average major diameter, average minor diameter, and aspect ratio of the bubbles in the adhesive layer can be determined as follows. Specifically, the adhesive layer is sliced ​​using a razor (Feather Corporation) on a plane parallel to the MD (Machine Direction) direction and the thickness direction to obtain an MD cut sample. The obtained MD cut sample is photographed using a digital microscope (for example, Keyence Corporation's "VHX-6000") under conditions such as a magnification of 200x and a measurement screen size of 1.8 mm × 1.3 mm. In the obtained photographed image, the bubble with the largest major diameter and the bubble with the second largest major diameter are selected, and the major and minor diameters of these bubbles are measured to calculate the aspect ratio. This operation is performed for three photographed images, and the average of the major diameters of the six bubbles is taken as the average major diameter of the bubbles in the adhesive layer. Furthermore, if the MD direction and the length direction of the adhesive layer are unknown, the adhesive layer is sliced ​​with a plane parallel to the thickness direction to obtain a cut sample. The slice is made so that the cutting direction is shifted by 30° from the direction from which the previous cut sample was made, and the aspect ratio is measured in the same manner as above. The above measurement is repeated until returning to the cutting direction of the first measurement, and the average of the major axes of the 12 bubbles measured is taken as the average major axis of the bubbles in the adhesive layer, the average of the minor axes of the 12 bubbles is taken as the average minor axis of the bubbles in the adhesive layer, and the average of the aspect ratios of the 12 bubbles is taken as the aspect ratio of the bubbles in the adhesive layer.

[0118] Methods for adjusting the average major diameter, average minor diameter, and aspect ratio of the bubbles in the adhesive layer include, for example, a method of forming the adhesive layer by mechanically stretching and compressing it, a method of including a surfactant or stabilizer in the adhesive composition that forms the adhesive layer, and a method of selecting foaming particles with different particle sizes.

[0119] The thickness of the adhesive layer described above has a preferred lower limit of 50 μm and a preferred upper limit of 500 μm. When the thickness of the adhesive layer is 50 μm or more, the adhesive strength of the adhesive layer is further improved. When the thickness of the adhesive layer is 500 μm or less, the adhesive layer has appropriate flexibility, so the stress relaxation properties of the adhesive layer are further improved, and the adhesive layer has better shock absorption properties. In addition, the step-following ability of the adhesive tape of this embodiment is further improved. A more preferred lower limit for the thickness of the adhesive layer is 80 μm, a more preferred upper limit is 400 μm, an even more preferred lower limit is 100 μm, an even more preferred upper limit is 300 μm, and an even more preferred upper limit is 200 μm. Examples of the thickness of the adhesive layer include 50 μm to 500 μm, 80 μm to 400 μm, 100 μm to 300 μm, 100 μm to 200 μm, etc.

[0120] In this specification, thickness can be measured using a dial thickness gauge (for example, Mitutoyo's "ABS Digimatic Indicator").

[0121] Preferably, the average major diameter of the bubbles in the adhesive layer is 0.80 times or less the thickness of the adhesive layer. Having an average major diameter of 0.80 times or less the thickness of the adhesive layer improves the bending rigidity of the adhesive layer, making it easier to impart superior deformation resistance (especially bending resistance) to the resulting adhesive tape. Furthermore, the increased tensile strength of the adhesive layer suppresses cohesive failure, thus improving the adhesive strength of the adhesive tape in this embodiment. More preferably, the average major diameter of the bubbles is 0.70 times or less the thickness of the adhesive layer, and even more preferably 0.60 times or less. Also, preferably, the average major diameter of the bubbles is 0.05 times or more the thickness of the adhesive layer. Having an average major diameter of 0.05 times or more the thickness of the adhesive layer improves the stress relaxation properties of the adhesive layer, resulting in a more shock-absorbing adhesive tape. More preferably, the average major diameter of the bubbles is 0.10 times or more the thickness of the adhesive layer. In other words, the average major diameter of the bubbles is preferably 0.05 to 0.80 times the thickness of the adhesive layer, more preferably 0.10 to 0.70 times, and even more preferably 0.10 to 0.60 times.

[0122] Preferably, the adhesive layer has a structure in which no air bubbles are exposed on the surface in the thickness direction. Because the adhesive layer does not have air bubbles exposed on the surface in the thickness direction, the area of ​​the adhesive interface between the adhesive layer and the adherend is increased, and thus the adhesive strength of the adhesive tape of this embodiment is further improved.

[0123] One method for creating a structure in which no air bubbles are exposed on the surface in the thickness direction of the adhesive layer is to use an adhesive composition containing large foaming particles, thereby suppressing the floating of foaming particles to the liquid surface during the solution coating of the adhesive composition in the adhesive layer formation process.

[0124] The adhesive tape of this embodiment may have layers other than the adhesive layer described above.

[0125] The adhesive tape of this embodiment may or may not have a base material. If the adhesive tape of this embodiment has a base material, the resulting adhesive tape can be given better reworkability. If the adhesive tape of this embodiment does not have a base material, the resulting adhesive tape will have improved shock absorption. In addition, since the resulting adhesive tape will be thinner, it will be more suitable for use in fixing electronic equipment components or automotive components. In particular, if the adhesive tape of this embodiment does not have a base material, it is preferable that the adhesive tape of this embodiment consists only of the adhesive layer described above.

[0126] If the adhesive tape of this embodiment has a base material, it may be a single-sided adhesive tape having the adhesive layer on one side of the base material, or it may be a double-sided adhesive tape having adhesive layers on both sides of the base material. Furthermore, if the adhesive tape of this embodiment is a double-sided adhesive tape, at least one of the adhesive layers may be an adhesive layer having the foamed structure described above.

[0127] If the adhesive tape of this embodiment has a base material, the base material is preferably made of a bio-derived material, from the viewpoint of increasing the bio-derived carbon content of the adhesive tape as a whole. Examples of the bio-derived material include polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS), as well as polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetylcellulose (TAC), cellulose, and polyamide (PA), all of which are derived from plants.

[0128] Furthermore, from the perspective of reducing environmental impact by decreasing the use of new petroleum resources and suppressing carbon dioxide emissions, base materials made from recycled resources may be used. Methods for recycling resources include, for example, recovering waste from packaging containers, home appliances, automobiles, construction materials, food, etc., or waste generated in the manufacturing process, and using the extracted materials again as raw materials by washing, decontamination, or decomposition by heating or fermentation. Examples of base materials using the above recycled resources include films and nonwoven fabrics made from PET, PBT, PE, PP, PA, etc., using recovered plastics that have been re-resinated as raw materials. Alternatively, the recovered waste may be burned and used as thermal energy for the manufacture of base materials and their raw materials, or the oils and fats contained in the recovered waste may be mixed with petroleum, fractionally distilled, and refined to be used as raw materials.

[0129] When the adhesive tape of this embodiment has a base material, examples of base material types that can be used for the base material include films and nonwoven fabrics. Among these, films are preferred from the viewpoint of the base material having excellent stiffness and making it easier to impart excellent deformation resistance (especially bending resistance) to the adhesive tape of this embodiment, and films containing PES or films containing PA are more preferred. Examples of PA include nylon 11, nylon 1010, nylon 610, nylon 510, nylon 410, etc., which are made from castor oil, and nylon 56, etc., which are made from cellulose.

[0130] The preferred lower limit for the thickness of the above-mentioned substrate is 3.5 μm, and the preferred upper limit is 1000 μm. By having the thickness of the above-mentioned substrate within the above range, the balance between the flexibility and rigidity of the substrate is improved, and the adhesive tape of this embodiment tends to have better deformation resistance (especially bending resistance) while maintaining excellent shock absorption. A more preferred lower limit for the thickness of the above-mentioned substrate is 5 μm, a more preferred upper limit is 500 μm, an even more preferred lower limit is 10 μm, an even more preferred upper limit is 300 μm, an even more preferred lower limit is 30 μm, an even more preferred upper limit is 200 μm, and a particularly preferred upper limit is 100 μm. Examples of the thickness of the above-mentioned substrate include 3.5 μm to 1000 μm, 5 μm to 500 μm, 10 μm to 300 μm, 30 μm to 200 μm, 30 μm to 100 μm, etc.

[0131] The adhesive tape of this embodiment may have a second adhesive layer without a foamed structure on at least one side of the adhesive layer. Therefore, the adhesive tape of this embodiment may have the second adhesive layer on one side of the adhesive layer, or it may have the second adhesive layer on both sides of the adhesive layer. By having the second adhesive layer on at least one side of the adhesive layer of this embodiment, the interlayer strength of the resulting adhesive tape is further improved, and the adhesive strength of the adhesive tape of this embodiment is further improved.

[0132] The adhesive contained in the second adhesive layer described above is not particularly limited as long as it does not impair the effects of the present invention, and conventionally known adhesives can be used. Specifically, examples include acrylic adhesives, urethane adhesives, rubber adhesives, silicone adhesives, etc. Among these, acrylic adhesives are preferred from the viewpoint of the design range of the adhesive and the wide range of adherend selectivity, and acrylic adhesives containing the above-mentioned acrylic copolymer in the adhesive layer having the foam structure described above are more preferred from the viewpoint of further improving the adhesive strength of the adhesive tape of this embodiment.

[0133] The thickness of the second adhesive layer described above has a preferred lower limit of 5 μm and a preferred upper limit of 100 μm. When the thickness of the second adhesive layer is 5 μm or more, the second adhesive layer exhibits greater adhesive strength to various materials, thereby improving the handling of the adhesive tape of this embodiment. When the thickness of the second adhesive layer is 100 μm or less, the adhesive tape of this embodiment can exhibit better deformation resistance. A more preferred lower limit for the thickness of the second adhesive layer is 10 μm, a more preferred upper limit is 90 μm, an even more preferred lower limit is 15 μm, and an even more preferred upper limit is 80 μm. Examples of the thickness of the second adhesive layer include 5 μm to 100 μm, 10 μm to 90 μm, 15 μm to 80 μm, etc.

[0134] The method for manufacturing the adhesive tape of this embodiment is not particularly limited, and conventionally known methods can be used. For example, the method for manufacturing an adhesive tape consisting only of the adhesive layer described above is as follows. First, a solvent is added to an acrylic copolymer, tackifying resin, foamed particles, etc., to prepare a solution of the adhesive composition. Next, the prepared adhesive composition solution is applied to the release surface of a release film, and the solvent in the solution is dried and removed to form an adhesive layer having a foamed structure. Then, by placing the release surface of the release film on top of the formed adhesive layer, an adhesive tape can be obtained in which the surface of the adhesive layer is covered with the release film.

[0135] Furthermore, the method for manufacturing an adhesive tape having the above-mentioned substrate and having the adhesive layer on at least one side of the substrate is as follows. That is, in the same manner as the method for manufacturing an adhesive tape consisting only of the above-mentioned adhesive layer, the formed foamed adhesive layer is bonded to the substrate, pressed together using a rubber roller to create a laminated and integrated structure, and then cured in a 40°C environment for 72 hours to obtain an adhesive tape having an adhesive layer on one side of the substrate. Alternatively, the adhesive composition may be directly applied to the substrate, dried to form an adhesive layer, and then the release treatment surface of a release film may be placed on top of the formed adhesive layer. Alternatively, an adhesive tape having adhesive layers on both sides of the substrate can be obtained by placing an arbitrary adhesive layer prepared on the other side of the substrate and then laminating and integrating it.

[0136] Furthermore, the method for manufacturing an adhesive tape having the second adhesive layer on at least one side of the adhesive layer is as follows. Specifically, in the same manner as the method for manufacturing an adhesive tape consisting only of the adhesive layer described above, the adhesive layer having a foamed structure formed and the fabricated second adhesive layer are superimposed, then laminated and integrated by pressing them together using a rubber roller, and then cured for 72 hours in a 40°C environment to produce an adhesive tape having the second adhesive layer on one side of the adhesive layer. In addition, by performing the same operation on the other side of the adhesive layer in the adhesive tape having the second adhesive layer on one side of the fabricated adhesive layer, an adhesive tape having the second adhesive layer on both sides of the adhesive layer can be produced.

[0137] Furthermore, adhesive tapes having the second adhesive layer on at least one side of the adhesive layer can also be manufactured using a multilayer extrusion extruder. Specifically, the adhesive composition forming the adhesive layer and the adhesive composition forming the second adhesive layer are supplied to a multilayer extrusion extruder, and after melt-mixing, a sheet-like adhesive tape base roll in which the adhesive layer and the second adhesive layer are laminated is extruded to produce the tape.

[0138] In this embodiment, the preferred lower limit of the 180° peel force against SUS at 23°C on the adhesive layer having the foam structure (hereinafter simply referred to as "the 180° peel force of the adhesive tape against SUS at 23°C") is 10 N / 25 mm. A 180° peel force of 10 N / 25 mm or more on SUS at 23°C results in superior adhesive strength. A more preferred lower limit for the 180° peel force of the adhesive tape against SUS at 23°C is 12 N / 25 mm, an even more preferred lower limit is 15 N / 25 mm, and an even more preferred lower limit is 20 N / 25 mm. There is no particular upper limit for the 180° peel force of the adhesive layer against SUS at 23°C, but approximately 80 N / 25 mm is a practical upper limit. A more preferred upper limit for the peel force is 50 N / 25 mm. Furthermore, examples of the 180° peel force of the adhesive layer on SUS at 23°C include 10N / 25mm to 80N / 25mm, 12N / 25mm to 80N / 25mm, 15N / 25mm to 50N / 25mm, 20N / 25mm to 50N / 25mm, and so on.

[0139] The 180° peel force of the above adhesive tape against SUS at 23°C can be measured by the following method. First, one side of the adhesive tape (the side not to be measured) is backed with a 23 μm thick polyethylene terephthalate film by pressing it down with a 2 kg rubber roller at a speed of 300 mm / min for one back-and-forth motion, if necessary. Next, a test piece is cut to a width of 25 mm and a length of 75 mm. The test piece is then attached to a SUS304 plate (a SUS304 plate that has been cleaned with ethanol and then wiped dry), with the measurement surface of the adhesive layer of the adhesive tape pressed down with a 2 kg rubber roller at a speed of 300 mm / min for one back-and-forth motion. Finally, the test sample is cured for 20 minutes in an environment of 23°C and 50% RH. The obtained test samples can be measured by peeling the adhesive tape from the SUS304 plate in accordance with JIS Z 0237:2009, under conditions of 23°C, 50% RH, a tensile speed of 300 mm / min, and a peeling angle of 180°.

[0140] Methods for adjusting the 180° peel force of the above adhesive tape against SUS at 23°C include, for example, changing the composition of the acrylic copolymer contained in the adhesive layer (for example, increasing the content of constituent units derived from monomers having crosslinkable functional groups), adjusting the weight-average molecular weight, polydispersity, etc., of the acrylic copolymer, including a tackifying resin in the adhesive layer, adjusting the thickness of the adhesive layer, adjusting the content of the crosslinking agent contained in the adhesive composition, and adjusting the type and thickness of the substrate.

[0141] The preferred lower limit for the thickness of the adhesive tape in this embodiment is 60 μm, and the preferred upper limit is 300 μm. A thickness of 60 μm or more in this embodiment further improves the shock absorption of the resulting adhesive tape. A thickness of 300 μm or less in this embodiment makes it easier to impart superior deformation resistance (especially bending resistance) to the resulting adhesive tape, making it more suitable for fixing electronic equipment components or automotive components. A more preferred lower limit for the thickness of the adhesive tape in this embodiment is 80 μm, a more preferred upper limit is 250 μm, an even more preferred lower limit is 100 μm, and an even more preferred upper limit is 200 μm. Examples of suitable thicknesses for the adhesive tape in this embodiment include 60 μm to 300 μm, 80 μm to 250 μm, 100 μm to 200 μm, and so on. Furthermore, the term "thickness of adhesive tape" as used herein does not include the thickness of the separator, such as a release film, that protects the outermost adhesive layer of the adhesive tape.

[0142] The adhesive tape of this embodiment is not particularly limited in its use, but because it has excellent shock absorption properties, it can be suitably used for fixing parts, and is more suitably used for bonding and fixing internal components of electronic devices or in-vehicle components. Examples of the electronic devices include televisions, monitors, and portable electronic devices, and examples of the in-vehicle components include in-vehicle electronic devices. When using the adhesive tape of this embodiment to fix parts, a primer treatment may be performed by applying a primer (undercoat) to the surface of the parts to be bonded, and then the parts may be bonded and fixed with the adhesive tape of this embodiment. The primer is not particularly limited, and conventionally known primers can be used, such as epoxy primers, urethane primers, and acrylic primers.

[0143] Furthermore, the adhesive tape of this embodiment preferably has resistance to deformation such as bending and twisting (deformation resistance), and more preferably has bending resistance. An adhesive tape with excellent bending resistance can prevent damage to the adherend due to deformation of the adhesive tape caused by bending of the adherend, and is therefore more suitable for bonding and fixing components of thin electronic devices. Specifically, examples include fixing components in foldable display devices such as thin televisions and thin monitors, and more specifically, using it to fix a surface cover panel to a housing with uneven surfaces in a display device.

[0144] An electronic device including the adhesive tape of this embodiment is also one of these embodiments. The electronic device of this embodiment is not particularly limited as long as it includes the adhesive tape, but examples include electronic devices in which electronic components are bonded and fixed together with the adhesive tape, and specifically, for example, a display device in which a cover panel and a housing having irregularities are bonded and fixed together with the adhesive tape.

[0145] According to the present invention, an adhesive tape with excellent shock absorption properties can be provided. Furthermore, according to the present invention, an electronic device including the adhesive tape can be provided.

[0146] This is a schematic diagram of a test specimen used to evaluate shock absorption. This is a schematic diagram illustrating the method for evaluating shock absorption. This is a schematic diagram illustrating the test method for bending tests.

[0147] The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The materials used in the examples and comparative examples are as follows.

[0148] <Preparation of n-hexyl acrylic acid containing bio-derived carbon> Linoleic acid derived from castor oil was converted to linoleic acid hydroperoxide by lipoxygenase, and then a mixture containing n-hexylaldehyde was obtained by isomerase. By distillation of the obtained mixture, n-hexylaldehyde containing bio-derived carbon was obtained. Furthermore, by hydrogenation of the obtained n-hexylaldehyde containing bio-derived carbon, n-hexyl alcohol containing bio-derived carbon was obtained. By esterifying the obtained n-hexyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), n-hexyl acrylic acid containing bio-derived carbon was prepared.

[0149] <Preparation of n-heptyl acrylic acid containing bio-derived carbon> Ricinoleic acid derived from castor oil was cracked to obtain a mixture containing undecylenic acid and n-heptyl alcohol. Then, undecylenic acid was separated from the obtained mixture by distillation to obtain n-heptyl alcohol containing bio-derived carbon. By esterifying the obtained n-heptyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), n-heptyl acrylic acid containing bio-derived carbon was prepared.

[0150] <Preparation of Isobornyl Methacrylate Containing Biologically Derived Carbon> Pinene extracted from pine resin was isomerized to obtain camphene containing biologically derived carbon. By reacting camphene containing biologically derived carbon with methacrylic acid (manufactured by Mitsubishi Chemical Corporation), isobornyl methacrylate containing biologically derived carbon was prepared.

[0151] <Preparation of Lauryl Acrylate Containing Biologically Derived Carbon> Lauryl acrylate was prepared by the esterification reaction of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) and lauryl alcohol. Lauryl alcohol was prepared by hydrolyzing oils and fats contained in palm kernel oil, coconut oil, etc., and then hydrogen-reducing lauric acid, which was extracted by fractional distillation of the resulting fatty acids.

[0152] <Monomers that do not contain bio-derived carbon> ・Methyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・n-butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) ・Isostearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.) ・Ethylene-butylene macromonomer (ethylene-butylene macromonomer with an acryloyl group at one end, manufactured by Kraton Polymers, "HPVM-L1253", number average molecular weight: 7000) ・Acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) ・Styrene (manufactured by Tokyo Chemical Industry Co., Ltd.) ・2-hydroxyethyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.)

[0153] <Elastomer (E1)> ・Styrene-based elastomer A: SIS block copolymer (manufactured by Zeon Corporation, "Quintac 3620", styrene ratio 14%, diblock ratio 12%) ・Styrene-based elastomer B: SIS block copolymer (manufactured by Zeon Corporation, "Quintac 3520", styrene ratio 14%, diblock ratio 26%) ・Styrene-based elastomer C: SIS block copolymer (manufactured by Zeon Corporation, "Quintac 3280", styrene ratio 25%, diblock ratio 17%) ・Styrene-based elastomer D: SIS block copolymer (manufactured by Zeon Corporation, "Quintac 3270", styrene ratio 24%, diblock ratio 67%) ・Styrene-based elastomer E: SEPS block copolymer (manufactured by Kuraray Co., Ltd., "SEPTON2063") - Styrene-based elastomer F: SEBS block copolymer (manufactured by ENEOS Materials, "DYNARON 8300P")

[0154] <Expandable Particles> - Thermally expandable microcapsule A: Expancel 920DU40 (manufactured by Nippon Philite Co., Ltd., average particle size 40 μm) - Thermally expandable microcapsule B: Expancel 920DU80 (manufactured by Nippon Philite Co., Ltd., average particle size 80 μm) - Thermally expandable microcapsule C: EMC-20(B)R (manufactured by Nippon Philite Co., Ltd., average particle size 20 μm)

[0155] <Tackifying Resins> ・Terpene-based resin: YS Resin PX1000 (manufactured by Yasuhara Chemical Co., Ltd.) ・Terpene phenol-based resin: YS Polystar G150 (manufactured by Yasuhara Chemical Co., Ltd.) ・Rosin ester-based resin: Pencel D-135 (manufactured by Arakawa Chemical Industries, Ltd.)

[0156] <Coloring agent> ・Carbon black: Multi-rack A903 Black (manufactured by Toyo Color Co., Ltd.)

[0157] <Crosslinking agent> ・Isocyanate-based crosslinking agent: Desmodulo L-75 (manufactured by Covestro)

[0158] (Synthesis of acrylic copolymers A-I, L-O) (1) Synthesis of RAFT agent 0.902 g of 1,6-hexanedithiol, 1.83 g of carbon disulfide, and 11 mL of dimethylformamide were placed in a two-necked flask and stirred at 25°C. 2.49 g of triethylammonium was added dropwise over 15 minutes and stirred at 25°C for 3 hours. Next, 2.75 g of methyl-α-bromophenylacetic acid was added dropwise over 15 minutes and stirred at 25°C for 4 hours. Then, 100 mL of extraction solvent (n-hexane:ethyl acetate = 50:50) and 50 mL of water were added to the reaction mixture and liquid-liquid extraction was performed. The organic layers obtained from the first and second liquid-liquid extractions were mixed and washed sequentially with 50 mL of 1 M hydrochloric acid, 50 mL of water, and 50 mL of saturated brine. Sodium sulfate was added to the organic layer after washing and dried, then the sodium sulfate was filtered off, and the filtrate was concentrated using an evaporator to remove the organic solvent. The obtained concentrate was purified by silica gel column chromatography to obtain the RAFT agent.

[0159] (2) Synthesis of hard blocks having styrene-derived structural units 0.19 g of the obtained RAFT agent, a mixture of structural unit monomers in the proportions shown in Tables 1-2, and 0.035 g of 2,2'-azobis(2-methylbutyronitrile) (ABN-E) as a polymerization initiator, along with 80 g of ethyl acetate as a solvent, were placed in a two-necked flask, and the flask was heated to 85°C while purging the inside with nitrogen gas. The polymerization reaction was then carried out by stirring at 85°C for 6 hours (first stage reaction). After the first stage reaction was completed, 400 g of n-hexane was added to the flask, and the reaction product was precipitated by stirring. Unreacted structural unit monomers and the RAFT agent were filtered off, and the reaction product was dried under reduced pressure at 70°C to obtain hard blocks having styrene-derived structural units.

[0160] (3) Synthesis of Acrylic Copolymers Furthermore, a mixture of the constituent monomers of the soft block shown in Tables 1-2, 0.0027 g of 2,2'-azobis(2-methylbutyronitrile) (ABN-E) as a polymerization initiator, and 5 g of ethyl acetate as a solvent, along with the hard block having constituent units derived from styrene obtained earlier, were placed in a two-necked flask, and the flask was heated to 85°C while purging it with nitrogen gas. The polymerization reaction was then carried out by stirring at 85°C for 6 hours (second-stage reaction), and a reaction solution containing a block copolymer consisting of a hard block having constituent units derived from styrene and a soft block having constituent units derived from alkyl (meth)acrylate was obtained. A portion of the reaction solution was taken, 400 g of n-hexane was added to it, and the reaction product was precipitated by stirring. Unreacted monomers and solvent were filtered off, and the reaction product was dried under reduced pressure at 70°C to remove the block copolymer from the reaction solution. An acrylic copolymer having a triblock copolymer structure was synthesized by the above method. Subsequently, an ethyl acetate solution of the synthesized acrylic copolymer was prepared. Furthermore, the weight-average molecular weight of the obtained acrylic copolymer was measured using a 2690 Separations Module (Waters Inc.) as the measuring instrument, a GPC KF-806L column (Showa Denko Corporation), and ethyl acetate as the solvent, under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The results are shown in Tables 1 and 2.

[0161]

[0162]

[0163] (Example 1) (1) Preparation of adhesive tape To the solution of acrylic copolymer A obtained in the above-described "(synthesis of acrylic copolymer)", 0.6 parts by mass of thermally expandable microcapsules A as foaming particles and 30 parts by mass of ethyl acetate as a solvent were added to 100 parts by mass of solid content of acrylic copolymer A, and the mixture was thoroughly stirred to prepare a solution containing the adhesive composition. The prepared solution containing the adhesive composition was applied to the release surface of a 50 μm thick release PET film, and then heated at 115°C for 1 hour to dry the solvent and foam the layer of adhesive composition, thereby forming an adhesive layer with a thickness of 200 μm. The obtained adhesive layer was cut using a razor (Feather Corporation), and the surface in the thickness direction of the adhesive layer was observed using an optical microscope (Keyence Corporation, "VHX-6000"). The obtained adhesive layer had a structure in which no air bubbles were exposed on the surface in the thickness direction. After bonding the obtained adhesive layer to the release-treated surface of a 50 μm thick release PET film, and curing it in a 40°C environment for 48 hours, an adhesive tape with only an adhesive layer was obtained, and an adhesive tape with a release PET film, in which the surface of the adhesive layer was protected by the release PET film, was obtained.

[0164] (2) Measurement of the bio-derived carbon content of the adhesive layer The release PET films on both sides were peeled off from the obtained adhesive tape, and the bio-derived carbon content of the obtained adhesive layer was measured in accordance with ASTM D6866-24. The results are shown in Table 3.

[0165] (3) Measurement of the gel fraction of the adhesive layer The release PET film was peeled off one side of the obtained adhesive tape and bonded to a 23 μm thick base PET film (Futamura Chemical Co., Ltd., "FE2002"), and cut into a flat rectangular shape with a width of 20 mm and a length of 40 mm. The release PET film was then peeled off the other side of the adhesive tape to prepare a test piece, and its mass was measured. The test piece was immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The mass of the dried test piece was measured, and the gel fraction (mass %) was calculated using the above formula (I). The results are shown in Table 3.

[0166] (4) Measurement of the deemed density of the adhesive layer The release PET film on both sides is peeled off from the obtained adhesive tape, and the deemed density of the adhesive layer (g / cm³) is determined in accordance with JIS K 7222. ３ The following was measured. The results are shown in Table 3.

[0167] (5) Calculation of the ratio of thickness to the average major diameter of bubbles in the adhesive layer Using a razor (Feather Co., Ltd.), the adhesive layer of the obtained adhesive tape was sliced ​​in a plane parallel to the thickness direction to prepare cut samples. The prepared MD cut samples were photographed using a digital microscope (e.g., Keyence Corporation, "VHX-6000") at a magnification of 200x and a measurement screen size of 1.8 mm × 1.3 mm. In the obtained images, the bubble with the largest major diameter and the bubble with the second largest major diameter were selected. This operation was performed for three images, and the average of the major diameters of the six bubbles was taken as the average major diameter of the bubbles in the adhesive layer. Furthermore, the sample was sliced ​​so that the cutting direction was shifted by 30° from the direction in which the previous cut sample was prepared, and the aspect ratio was measured in the same manner as above. The above measurement was repeated until it returned to the cutting direction of the first measurement, and the average of the major diameters of the twelve bubbles measured was taken as the average major diameter of the bubbles in the adhesive layer. Then, using the average major diameter of the bubbles in the resulting adhesive layer, the ratio of the average major diameter of the bubbles to the thickness of the adhesive layer was calculated. The results are shown in Table 3.

[0168] (6) 180° peel strength of adhesive tape against SUS at 23°C One side of the obtained adhesive tape (the side not measured) was pressed onto a 23 μm thick polyethylene terephthalate film by running a 2 kg rubber roller back and forth once at a speed of 300 mm / min to create a test piece. The piece was then cut to a width of 25 mm and a length of 75 mm. Next, the adhesive layer on the other side of the prepared test piece was attached to a SUS304 plate (a SUS304 plate that had been washed with ethanol and then wiped dry), and pressed onto it by running a 2 kg rubber roller back and forth once at a speed of 300 mm / min. After that, it was cured for 20 minutes in an environment of 23°C and 50% RH to create a test sample. The obtained test samples were tested in accordance with JIS Z 0237:2009, by peeling the adhesive layer from the SUS304 plate at 23°C, 50% RH, a tensile speed of 300 mm / min, and a peel angle of 180°. The 180° peel force of the adhesive tape against SUS at 23°C was measured. The results are shown in Table 3.

[0169] (Examples 2-31, 34-39, Comparative Examples 1-3) Except for the fact that the composition and thickness of the adhesive layer were as shown in Tables 3-6 in "(1) Preparation of adhesive tape" described above, adhesive tapes were prepared and various measurements were taken in the same manner as in Example 1. The results are shown in Tables 3-6. In Examples 2-31, 34-39, and Comparative Examples 2-3, the adhesive layer had a foamed structure. When the adhesive layer obtained was cut using a razor (Feather Co., Ltd.) and the surface in the thickness direction of the adhesive layer was observed using an optical microscope (Keyence Corporation, "VHX-6000"), the obtained adhesive layer had a structure in which no air bubbles were exposed on the surface in the thickness direction. On the other hand, the adhesive layer in Comparative Example 1 did not have a foamed structure.

[0170] (Examples 32-33) The adhesive layer was formed in the same manner as in Example 1, except that the composition and thickness of the adhesive layer were as shown in Table 5. The adhesive layers in Examples 35-36 had a foamed structure. When the obtained adhesive layer was cut using a razor (Feather Co., Ltd.) and the surface in the thickness direction of the adhesive layer was observed using an optical microscope (Keyence Corporation, "VHX-6000"), the obtained adhesive layer had a structure in which no air bubbles were exposed on the surface in the thickness direction. The obtained adhesive layer was bonded to one side of the substrate as shown in Table 5, and then pressed down by running a 2 kg rubber roller back and forth once at a speed of 300 mm / min. Furthermore, an adhesive layer with the same composition and thickness was prepared and bonded to the other side of the substrate, and then pressed down by running a 2 kg rubber roller back and forth once at a speed of 300 mm / min to laminate and integrate it, and then cured for 1 hour in an environment of 23°C to obtain an adhesive tape having adhesive layers on both sides of the substrate. In Table 5, "PET film A" is Lumirror (thickness: 38 μm) manufactured by Toray Industries, Inc., and "PET film B" is Lumirror (thickness: 50 μm) manufactured by Toray Industries, Inc. Regarding the various measurements, the procedure was the same as in Example 1, except that in "(2) Measurement of the bio-derived carbon content of the adhesive layer," "(3) Measurement of the gel fraction of the adhesive layer," and "(4) Measurement of the deemed density of the adhesive layer," the adhesive layer was removed from the obtained adhesive tape using a cutter knife and then measured using the same method as in Example 1. The results are shown in Table 5.

[0171] <Evaluation> The adhesive tapes obtained in the examples and comparative examples were evaluated as follows. The results are shown in Tables 3 to 6.

[0172] (Impact Absorption) (1) Calculation of Impact Absorption Energy The obtained adhesive tape was cut to a size of 30 mm x 30 mm, and two SUS plates 3 with a size of 125 mm x 50 mm and a thickness of 2 mm were stacked on the cut adhesive tape 2 as shown in Figure 1 to create a test piece 1. As shown in Figure 2, the obtained test piece 1 was set up so that the pendulum 4 would hit only one of the SUS plates 3 on the test piece when it passed its lowest point. Then, a pendulum 4 with a mass of 1.0 kg was dropped from a height of 0.2 m (H in Figure 2) and hit the test piece 1, and the highest height h reached was measured. Using the obtained height h, the impact absorption energy in the test piece before heating was calculated from the following formula. Note that the lowest point reached by the pendulum 4 is set to 0 for height. Impact absorption energy in the test piece before heating (J) = mg(0.2 - h) (m: mass of the pendulum (kg), g: acceleration due to gravity (9.80 m / s) ２ ), h: measured height (m)

[0173] (2) Evaluation of the shock absorption performance of the adhesive tape Based on the calculated shock absorption energy, the shock absorption performance of the adhesive tape was evaluated according to the following criteria: A: The shock absorption energy was 1.00 J or more. B: The shock absorption energy was 0.50 J or more and less than 1.00 J. C: The shock absorption energy was 0.15 J or more and less than 0.50 J. D: The shock absorption energy was less than 0.15 J.

[0174] (Deformation Resistance) The deformation resistance of the adhesive tape was evaluated by performing the bending test shown in Figure 3. Aluminum alloy plates (SHAANXI SHWEW-E STEEL PIPE, "Aluminum 6061-T6", 1.6 mm thick, 25.4 mm wide, 203.2 mm long) were bonded to both sides of the obtained adhesive tape by applying a load of 1 MPa for 20 seconds at 65°C to laminate them together, and then cured by leaving them undisturbed at 23°C for 24 hours to produce a laminate 5. The produced laminate 5 was set up in a Tensilon (manufactured by A&D Company, Limited) used as a measuring instrument in accordance with JIS K 7171 as shown in Figure 3 (distance between compression jigs: 57.15 mm, distance between fixing jigs: 177.8 mm). Subsequently, the laminate 5 was compressed at a constant speed of 0.05 mm / s in an environment with a temperature of 23 ± 1°C and a humidity of 50 ± 5%, until the load reached 50 N. In the obtained stress-deformation curve, the slope of the line (stress / deformation) was calculated from two points on the stress-deformation curve: one with a stress of 20 N and another with a stress of 50 N. Based on the obtained slope of the line, the deformation resistance of the adhesive tape was evaluated according to the following criteria: A: The slope of the line was 17.0 N / mm or more. B: The slope of the line was 15.5 N / mm or more and less than 17.0 N / mm. C: The slope of the line was less than 15.5 N / mm. Even if the evaluation was "C", the adhesive tape of this embodiment can be used without problems depending on the application.

[0175]

[0176]

[0177]

[0178]

[0179] According to the present invention, an adhesive tape with excellent shock absorption properties can be provided. Furthermore, according to the present invention, an electronic device including the adhesive tape can be provided.

[0180] 1. Test specimen 2. Adhesive tape 3. SUS plate 4. Pendulum 5. Laminate 6. Compression jig 7. Fixing jig

Claims

1. The adhesive layer has a foamed structure, the adhesive layer contains an acrylic copolymer having constituent units derived from a (meth)acrylic compound, and the (meth)acrylic compound has an SP value of 9.45 (cal / cm³). ３ ) １／２ An adhesive tape characterized by containing the following (meth)acrylic compound.

2. The SP value in the acrylic copolymer is 9.45 (cal / cm³). ３ ) １／２ The adhesive tape according to claim 1, wherein the content of constituent units derived from the following (meth)acrylic compounds is 5% by mass or more and 85% by mass or less.

3. The adhesive tape according to claim 1 or 2, wherein the (meth)acrylic compound comprises an alkyl (meth)acrylate having an alkyl group having 12 or more carbon atoms.

4. The adhesive tape according to claim 1, 2, or 3, wherein the (meth)acrylic compound comprises a macromonomer having a (meth)acryloyl group and having a number average molecular weight of 2,000 or more and 30,000 or less.

5. The adhesive tape according to claim 4, wherein the macromonomer having a (meth)acryloyl group and having a number average molecular weight of 2,000 or more and 30,000 or less includes a constituent unit derived from an olefin polymer having a (meth)acryloyl group at its terminus.

6. The adhesive tape according to claim 5, wherein the content of constituent units derived from an olefin polymer having (meth)acryloyl groups at its ends in the acrylic copolymer is 5% by mass or more and 30% by mass or less.

7. The adhesive tape according to claim 1, 2, 3, 4, 5, or 6, wherein the (meth)acrylic compound comprises a constituent unit derived from an alkyl (meth)acrylate ester having an alkyl group having 1 to 8 carbon atoms, and the content of the constituent unit derived from the alkyl (meth)acrylate ester having an alkyl group having 1 to 8 carbon atoms in the acrylic copolymer is 30% by mass or more and less than 100% by mass.

8. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, or 7, wherein the (meth)acrylic compound comprises an alkyl (meth)acrylate having a linear or branched alkyl group with 6 to 8 carbon atoms.

9. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein the (meth)acrylic compound comprises an alkyl (meth)acrylate having an alkyl group having an aliphatic cyclic structure.

10. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the (meth)acrylic compound comprises a monomer having a crosslinkable functional group, and the content of constituent units derived from the monomer having a crosslinkable functional group in the acrylic copolymer is 0.1% by mass or more.

11. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the acrylic copolymer has constituent units derived from a vinyl aromatic compound, and the content ratio of constituent units derived from the vinyl aromatic compound in the acrylic copolymer is 2.5% by mass or more and 15% by mass or less.

12. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, wherein the acrylic copolymer has a weight-average molecular weight of 300,000 or more and 1,500,000 or less.

13. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, wherein the adhesive layer contains at least one elastomer selected from the group consisting of styrene-based elastomers, olefin-based elastomers, and urethane-based elastomers.

14. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, wherein the adhesive layer does not contain a tackifying resin, or the adhesive layer contains a tackifying resin, and the content of the tackifying resin is 50 parts by mass or less per 100 parts by mass of the acrylic copolymer.

15. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, wherein the adhesive layer contains a coloring agent.

16. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, wherein the adhesive layer has a structure derived from a crosslinking agent.

17. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, wherein the adhesive layer has bubbles derived from foaming particles.

18. The adhesive tape according to claim 17, wherein the foaming particles include thermally expandable microcapsules.

19. The adhesive tape according to claim 17 or 18, wherein the foaming particles have an average particle size of 60 μm or less.

20. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, or 19, wherein the adhesive layer has a gel fraction of 10% by mass or more and 70% by mass or less.

21. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, wherein the adhesive layer has a bio-derived carbon content of 15% or more.

22. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or 21, wherein the adhesive layer has an average major diameter of air bubbles that is 0.80 times or less the thickness of the adhesive layer.

23. The adhesive layer has an assumed density of 0.59 g / cm³. ３ 1.15g / cm or more ３ The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22.

24. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23, wherein the adhesive layer has a structure in which no air bubbles are exposed on the surface in the thickness direction.

25. An adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24, which does not have a base material.

26. The adhesive tape according to claim 25, comprising only the adhesive layer.

27. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24, comprising a base material and having the adhesive layer on at least one surface of the base material.

28. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or 27, wherein the adhesive tape has a second adhesive layer that does not have a foamed structure on at least one surface of the adhesive layer.

29. The adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, or 28, wherein the adhesive tape has a 180° peel force of 10 N / 25 mm or more at 23°C on the side with the adhesive layer having the foam structure.

30. An adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, used for bonding and fixing internal components of electronic equipment or in-vehicle components.

31. Electronic device comprising the adhesive tape according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30.

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