Adhesive tape and adhesive composition

Abstract

The purpose of the present invention is to provide an adhesive tape that has excellent adhesive force in high-temperature environments. The purpose of the present invention is also to provide an adhesive composition that has excellent adhesive force in high-temperature environments. The present invention is an adhesive tape that has an adhesive layer. The adhesive layer includes an acrylic copolymer. The shear storage modulus of the adhesive layer at 150°C as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz is at least 8.0×104 Pa but no more than 3.0×105 Pa, and the loss tangent (tanδ) of the adhesive layer at 150°C as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz is at least 0.10 but no more than 0.40.

Description

Adhesive tape and adhesive composition

[0001] The present invention relates to a pressure-sensitive adhesive tape and a pressure-sensitive adhesive composition.

[0002] Conventionally, adhesive tapes having an adhesive layer containing an adhesive have been widely used to fix components in electronic devices, vehicles, houses, and building materials (e.g., Patent Documents 1 to 3). Specifically, adhesive tapes have been 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 to a display panel module.

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

[0004] Demand for heat resistance in pressure-sensitive adhesive tapes used for fixing electronic device components and in-vehicle components has been increasing year by year, and in recent years, adhesive strength at high temperatures approaching 100° C. However, with conventional pressure-sensitive adhesive tapes, the cohesive force of the adhesive layer decreases in high-temperature environments, and as a result, sufficient adhesive strength is sometimes not obtained.

[0005] An object of the present invention is to provide a pressure-sensitive adhesive tape that exhibits excellent adhesive strength in high-temperature environments, and a pressure-sensitive adhesive composition that exhibits excellent adhesive strength in high-temperature environments.

[0006] Disclosure 1 provides a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer containing an acrylic copolymer, and the pressure-sensitive adhesive layer having a shear storage modulus of 8.0 × 10 at 150°C measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz. ４ Pa or more 3.0×10 ５The present disclosure 2 is a pressure-sensitive adhesive tape having a viscosity of 1 Pa or less and a loss tangent (tan δ) at 150°C of 0.10 to 0.40 as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz. The present disclosure 2 is the pressure-sensitive adhesive tape of the present disclosure 1, wherein the acrylic copolymer has structural units derived from a (meth)acrylic acid alkyl ester, the structural units derived from the (meth)acrylic acid alkyl ester include structural units derived from a (meth)acrylic acid alkyl ester having an alcohol-derived alkyl group with 1 to 4 carbon atoms, the content of the structural units derived from the (meth)acrylic acid alkyl ester having an alcohol-derived alkyl group with 1 to 4 carbon atoms is 50% by mass to 100% by mass, and the content of the structural units derived from the (meth)acrylic acid alkyl ester in the acrylic copolymer is 50% by mass to 90% by mass.

[0014] Disclosure 3 is the pressure-sensitive adhesive tape of Disclosure 2, wherein the structural units derived from the (meth)acrylic acid alkyl ester include structural units derived from the (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 2, and the content of the structural units derived from the (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 2 is 10% by mass to 80% by mass. Disclosure 4 is the pressure-sensitive adhesive tape of Disclosure 1, 2, or 3, wherein the acrylic copolymer has structural units derived from a polar functional group-containing monomer, and the content of the structural units derived from the polar functional group-containing monomer in the acrylic copolymer is 3% by mass to 15% by mass. Disclosure 5 is the pressure-sensitive adhesive tape of Disclosure 4, wherein the structural units derived from the polar functional group-containing monomer include at least one structural unit selected from the group consisting of structural units derived from a carboxy group-containing monomer and structural units derived from a hydroxyl group-containing monomer. The present disclosure 6 is the pressure-sensitive adhesive tape of the present disclosure 1, 2, 3, 4, or 5, wherein the acrylic copolymer has a structural unit derived from an olefin copolymer having a terminal polymerizable unsaturated double bond.

[0014] Disclosure 7 is the pressure-sensitive adhesive tape of Disclosure 6, wherein the acrylic copolymer contains 5% by mass or more and 50% by mass or less of the structural unit derived from an olefin-based copolymer having a terminal polymerizable unsaturated double bond. Disclosure 8 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, or 7, wherein the acrylic copolymer has a weight-average molecular weight of 750,000 or more and less than 1,500,000. Disclosure 9 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, or 8, wherein the pressure-sensitive adhesive layer further contains a silane coupling agent. Disclosure 10 is the pressure-sensitive adhesive tape of Disclosure 9, wherein the content of the silane coupling agent is 0.1 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the acrylic copolymer. Disclosure 11 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the pressure-sensitive adhesive layer further contains a tackifier resin.

[0023] Disclosure 12 is the pressure-sensitive adhesive tape of Disclosure 11, wherein the tackifier resin comprises at least one selected from the group consisting of a terpene phenol-based resin, a rosin-based resin, and a xylene-based resin. Disclosure 13 is the pressure-sensitive adhesive tape of Disclosure 11 or 12, wherein the content of the tackifier resin is 20 parts by mass or less per 100 parts by mass of the acrylic copolymer. Disclosure 14 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, wherein the pressure-sensitive adhesive layer has a gel fraction of 10% by mass or more and 85% by mass or less. Disclosure 15 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, wherein the pressure-sensitive adhesive layer has a thickness of 5 μm or more and 200 μm or less. Disclosure 16 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, having a substrate. Disclosure 17 is the pressure-sensitive adhesive tape of Disclosure 16, wherein the substrate comprises at least one selected from the group consisting of a nonwoven fabric, a polyester film, a polyimide film, a polyamide film, a polyether ether ketone film, a polyphenylene ether film, and a polyphenylene sulfide film. Disclosure 18 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17, wherein the thickness of the entire pressure-sensitive adhesive tape is 50 μm or more and 200 μm or less.The present disclosure 19 is the pressure-sensitive adhesive tape of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18, which is used to fix an electronic device component or an in-vehicle component. Disclosure 20 is a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer contains an acrylic copolymer having structural units derived from a (meth)acrylic acid alkyl ester, structural units derived from an olefin-based copolymer having a terminal polymerizable unsaturated double bond, and structural units derived from a polar functional group-containing monomer, wherein the structural units derived from the (meth)acrylic acid alkyl ester include structural units derived from a (meth)acrylic acid alkyl ester in which an alcohol-derived alkyl group has 1 to 4 carbon atoms, and the structural units derived from the (meth)acrylic acid alkyl ester account for 50% by mass or more and 100% by mass or less of the structural units derived from the (meth)acrylic acid alkyl ester in which the alcohol-derived alkyl group has 1 to 4 carbon atoms, the structural units derived from the (meth)acrylic acid alkyl ester account for 50% by mass or more and 90% by mass or less of the structural units derived from the (meth)acrylic acid alkyl ester, the acrylic copolymer has a weight-average molecular weight of 500,000 or more and less than 1,500,000, and the acrylic copolymer has a weight-average molecular weight of 750,000 or more and less than 1,500,000. Disclosure 21 is the pressure-sensitive adhesive tape of Disclosure 20, wherein the structural units derived from the (meth)acrylic acid alkyl ester include structural units derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 2, and the content of the structural units derived from the (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 2 is 10% by mass or more and 80% by mass or less. Disclosure 22 is the pressure-sensitive adhesive tape of Disclosure 20 or 21, wherein the structural units derived from the polar functional group-containing monomer include at least one structural unit selected from the group consisting of structural units derived from a carboxy group-containing monomer and structural units derived from a hydroxy group-containing monomer.

[0023] Disclosure 23 is the pressure-sensitive adhesive tape of Disclosures 20, 21, or 22, wherein the acrylic copolymer contains from 5% by mass to 50% by mass of structural units derived from an olefin-based copolymer having a terminal polymerizable unsaturated double bond. Disclosure 24 is the pressure-sensitive adhesive tape of Disclosures 20, 21, 22, or 23, wherein the pressure-sensitive adhesive layer further contains a silane coupling agent. Disclosure 25 is the pressure-sensitive adhesive tape of Disclosure 24, wherein the content of the silane coupling agent is from 0.1 parts by mass to 3.0 parts by mass per 100 parts by mass of the acrylic copolymer. Disclosure 26 is the pressure-sensitive adhesive tape of Disclosures 20, 21, 22, 23, 24, or 25, wherein the pressure-sensitive adhesive layer further contains a tackifier resin. Disclosure 27 is the pressure-sensitive adhesive tape of Disclosure 26, wherein the tackifier resin comprises at least one selected from the group consisting of a terpene phenol-based resin, a rosin-based resin, and a xylene-based resin.

[0037] Disclosure 28 is the pressure-sensitive adhesive tape of Disclosure 26 or 27, wherein the content of the tackifier resin is 20 parts by mass or less per 100 parts by mass of the acrylic copolymer. Disclosure 29 is the pressure-sensitive adhesive tape of Disclosure 20, 21, 22, 23, 24, 25, 26, 27, or 28, wherein the pressure-sensitive adhesive layer has a gel fraction of 10% by mass or more and 85% by mass or less. Disclosure 30 is the pressure-sensitive adhesive tape of Disclosure 20, 21, 22, 23, 24, 25, 26, 27, 28, or 29, wherein the pressure-sensitive adhesive layer has a thickness of 5 μm or more and 200 μm or less. Disclosure 31 is the pressure-sensitive adhesive tape of Disclosure 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30, having a substrate.

[0033] Disclosure 32 is the pressure-sensitive adhesive tape of Disclosure 31, wherein the substrate comprises at least one selected from the group consisting of a nonwoven fabric, a polyester film, a polyimide film, a polyamide film, a polyether ether ketone film, a polyphenylene ether film, and a polyphenylene sulfide film. Disclosure 33 is the pressure-sensitive adhesive tape of Disclosures 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, or 32, wherein the overall thickness of the pressure-sensitive adhesive tape is 50 μm or more and 200 μm or less. Disclosure 34 is the pressure-sensitive adhesive tape of Disclosures 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, or 33, which is used to fix electronic device components or in-vehicle components.The present disclosure 35 is a pressure-sensitive adhesive composition comprising an acrylic copolymer having structural units derived from a (meth)acrylic acid alkyl ester, structural units derived from an olefin copolymer having a terminal polymerizable unsaturated double bond, and structural units derived from a polar functional group-containing monomer, and an organic solvent, wherein the structural units derived from the (meth)acrylic acid alkyl ester include structural units derived from a (meth)acrylic acid alkyl ester in which the alkyl group derived from an alcohol has 1 to 4 carbon atoms, the content of the structural units derived from the (meth)acrylic acid alkyl ester in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms is 50 to 100 mass%, the content of the structural units derived from the (meth)acrylic acid alkyl ester in the acrylic copolymer is 50 to 90 mass%, the content of the structural units derived from the (meth)acrylic acid alkyl ester in the acrylic copolymer is 3 to 15 mass%, and the weight-average molecular weight of the acrylic copolymer is 750,000 to less than 1,500,000.

[0047] Disclosure 36 relates to the pressure-sensitive adhesive composition of Disclosure 35, wherein the structural units derived from the (meth)acrylic acid alkyl ester include structural units derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 2, and the content of the structural units derived from the (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 2 is 10% by mass or more and 80% by mass or less. The present invention will be described in detail below. The pressure-sensitive adhesive tape according to Disclosure 1 will also be referred to as the "pressure-sensitive adhesive tape of Invention 1," and the pressure-sensitive adhesive tape according to Disclosure 20 will also be referred to as the "pressure-sensitive adhesive tape of Invention 2." Furthermore, matters common to the pressure-sensitive adhesive tape of Invention 1 and the pressure-sensitive adhesive tape of Invention 2 will not be particularly specified, or will be described as the "pressure-sensitive adhesive tape of the present invention."

[0007] The present inventors investigated adjusting the shear storage modulus and loss tangent of a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing an acrylic copolymer within specific ranges under high-temperature conditions. As a result, they found that a pressure-sensitive adhesive tape with excellent adhesive strength under high-temperature conditions can be obtained, leading to the completion of Invention 1. The present inventors also investigated improving the cohesive strength of a pressure-sensitive adhesive layer under high-temperature conditions in a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer by incorporating a relatively highly polar acrylic olefin copolymer having a specific composition into the pressure-sensitive adhesive layer. Furthermore, the present inventors investigated incorporating relatively polar monomers, such as an alkyl acrylate ester having a small carbon number and a polar functional group-containing monomer, in specific content ratios as the monomers constituting the acrylic olefin copolymer, and furthermore, adjusting the resulting acrylic olefin copolymer to a specific weight-average molecular weight. As a result, they found that a pressure-sensitive adhesive layer with improved cohesive strength under high-temperature conditions can be obtained, leading to the completion of Invention 2.

[0008] The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer. In the pressure-sensitive adhesive tape of invention 1, the shear storage modulus (G') of the pressure-sensitive adhesive layer measured at 150°C by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz (hereinafter, sometimes simply referred to as "shear storage modulus at 150°C") has a lower limit of 8.0 × 10 ４ Pa, with an upper limit of 3.0 × 10 ５ The pressure-sensitive adhesive layer has a shear storage modulus of 8.0 × 10 at 150°C. ４ When the shear storage modulus of the pressure-sensitive adhesive layer at 150°C is 3.0 x 10 Pa or more, the cohesive strength of the pressure-sensitive adhesive layer at high temperatures is increased, and the pressure-sensitive adhesive tape of invention 1 has excellent adhesive strength in a high-temperature environment. ５ By setting the shear storage modulus at 150°C to 1.0 x 10 Pa or less, the pressure-sensitive adhesive layer does not become too hard at high temperatures, and the pressure-sensitive adhesive tape of invention 1 has excellent adhesive strength in a high-temperature environment. ５ Pa, the preferred upper limit is 2.5 × 10 ５ Pa, and a more preferable lower limit is 1.2 × 10５ Pa, and a more preferable upper limit is 2.0 × 10 ５ In the pressure-sensitive adhesive tape of invention 2, the shear storage modulus of the pressure-sensitive adhesive layer at 150°C is preferably 8.0 × 10 Pa. ４ Pa, and the preferred upper limit is 3.0 × 10 ５ The pressure-sensitive adhesive layer has a shear storage modulus of 8.0 × 10 at 150°C. ４ When the shear storage modulus of the pressure-sensitive adhesive layer at 150°C is 3.0 x 10 Pa or more, the cohesive strength of the pressure-sensitive adhesive layer at high temperatures is further increased, and the pressure-sensitive adhesive tape of invention 2 has superior adhesive strength in a high-temperature environment. ５ By setting the shear storage modulus at 150°C to 1.0 x 10 Pa or less, the pressure-sensitive adhesive layer does not become too hard at high temperatures, and the pressure-sensitive adhesive tape of invention 2 has superior adhesive strength in a high-temperature environment. ５ Pa, and a more preferable upper limit is 2.5×10 ５ Pa, and a more preferable lower limit is 1.2 × 10 ５ Pa, and a more preferable upper limit is 2.0 × 10 ５ It is Pa.

[0009] In the pressure-sensitive adhesive tape of the first invention, the loss tangent (tan δ) at 150°C (hereinafter sometimes simply referred to as "loss tangent at 150°C") of the pressure-sensitive adhesive layer measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz has a lower limit of 0.10 and an upper limit of 0.40. When the loss tangent at 150°C of the pressure-sensitive adhesive layer is 0.10 or more, the pressure-sensitive adhesive layer becomes flexible and can easily adhere to an adherend. When the loss tangent at 150°C of the pressure-sensitive adhesive layer is 0.40 or less, the cohesive strength of the pressure-sensitive adhesive layer at high temperatures is improved, and the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in high-temperature environments, so that the pressure-sensitive adhesive tape of the first invention has excellent adhesive strength in high-temperature environments. The loss tangent at 150°C of the pressure-sensitive adhesive layer is preferably 0.12 at its lower limit, 0.35 at its upper limit, 0.14 at its more preferred limit, and 0.30 at its upper limit. Furthermore, in the pressure-sensitive adhesive tape of invention 2, the loss tangent at 150°C preferably has a lower limit of 0.10 and an upper limit of 0.40. When the loss tangent at 150°C of the pressure-sensitive adhesive layer is 0.10 or more, the pressure-sensitive adhesive layer becomes more flexible and can more easily adhere to the adherend. When the loss tangent at 150°C of the pressure-sensitive adhesive layer is 0.40 or less, the cohesive strength of the pressure-sensitive adhesive layer at high temperatures is further improved, and the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in high-temperature environments, so that the pressure-sensitive adhesive tape of invention 2 has superior adhesive strength in high-temperature environments. The loss tangent at 150°C of the pressure-sensitive adhesive layer is more preferably 0.12, more preferably 0.35, even more preferably 0.14, and even more preferably 0.30.

[0010] The shear storage modulus at 150°C and the loss tangent (tan δ) at 150°C of the pressure-sensitive adhesive layer can be measured by dynamic viscoelasticity measurement. That is, the dynamic viscoelasticity spectrum of the obtained pressure-sensitive adhesive layer is measured using a dynamic viscoelasticity measurement device (for example, "DVA-200" manufactured by IT Measurement & Control Co., Ltd.) under conditions of a nitrogen atmosphere, a shear direction, a frequency of 1 Hz, a heating rate of 5°C / min, a temperature range of -100°C to 200°C, and a strain of 0.08%, thereby obtaining the shear storage modulus at 150°C and the loss tangent (tan δ) at 150°C of the pressure-sensitive adhesive layer. When the thickness of the pressure-sensitive adhesive layer is less than 500 μm, a pressure-sensitive adhesive layer for measurement is prepared by laminating pressure-sensitive adhesive layers so as to have a thickness of 500 μm or more, and dynamic viscoelasticity measurement is performed.

[0011] Methods for adjusting the shear storage modulus at 150°C of the pressure-sensitive adhesive layer include a method for adjusting the polarity of the acrylic copolymer described below (a method for adjusting the content of an alcohol-derived (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms described below, a method for adjusting the content of a structural unit derived from a polar functional group-containing monomer described below, etc.), a method for adjusting the molecular weight of the acrylic copolymer, and a method for adjusting the type and content of a tackifier resin, crosslinking agent, or silane coupling agent described below.

[0012] Methods for adjusting the loss tangent (tanδ) at 150°C of the pressure-sensitive adhesive layer include a method for adjusting the polarity of the acrylic copolymer described below (a method for adjusting the content of an alcohol-derived (meth)acrylic acid alkyl ester having 1 to 4 carbon atoms described below, a method for adjusting the content of a structural unit derived from a polar functional group-containing monomer described below, etc.), a method for adjusting the molecular weight of the acrylic copolymer, and a method for adjusting the type and content of a tackifier resin, crosslinking agent, or silane coupling agent described below.

[0013] In the pressure-sensitive adhesive tape of the present invention, the pressure-sensitive adhesive layer contains an acrylic copolymer. The acrylic copolymer preferably has a structural unit derived from a (meth)acrylic acid alkyl ester. In this specification, "(meth)acrylic" means acrylic or methacrylic.

[0014] In the pressure-sensitive adhesive tape of the second aspect, the structural unit derived from the (meth)acrylic acid alkyl ester comprises a structural unit derived from a (meth)acrylic acid alkyl ester in which the alkyl group derived from an alcohol has 1 to 4 carbon atoms. Furthermore, in the pressure-sensitive adhesive tape of the first aspect, the structural unit derived from the (meth)acrylic acid alkyl ester preferably comprises a structural unit derived from a (meth)acrylic acid alkyl ester in which the alkyl group derived from an alcohol has 1 to 4 carbon atoms. When the structural unit derived from the (meth)acrylic acid alkyl ester comprises a structural unit derived from a (meth)acrylic acid alkyl ester in which the alkyl group derived from an alcohol has 1 to 4 carbon atoms, the polarity of the acrylic copolymer is increased, thereby enhancing the cohesive strength of the pressure-sensitive adhesive layer. As a result, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is improved, and in particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in high-temperature environments, thereby enhancing the adhesive strength of the pressure-sensitive adhesive tape of the present invention in high-temperature environments. In this specification, the term "alcohol-derived alkyl group" refers to an alkyl group bonded to an oxygen atom of an ester bond in the (meth)acrylic acid alkyl ester.

[0015] In the pressure-sensitive adhesive tape of the second invention, the lower limit of the content of structural units derived from a (meth)acrylic acid alkyl ester in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms is 50% by mass. Furthermore, in the pressure-sensitive adhesive tape of the first invention, the lower limit of the content of structural units derived from a (meth)acrylic acid alkyl ester in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms is preferably 50% by mass. When the content of structural units derived from a (meth)acrylic acid alkyl ester in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms is 50% by mass or more, the polarity of the acrylic copolymer is increased, thereby increasing the cohesive strength of the pressure-sensitive adhesive layer, and as a result, improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention. In particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in a high-temperature environment, thereby improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention in a high-temperature environment. In the pressure-sensitive adhesive tape of invention 2, the preferred lower limit of the content of structural units derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 4 is 60 mass%, more preferably 70 mass%. In the pressure-sensitive adhesive tape of invention 1, the preferred lower limit of the content of structural units derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 4 is 60 mass%, even more preferably 70 mass%. In the pressure-sensitive adhesive tape of the present invention, the upper limit of the content of structural units derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 4 is 100 mass%, i.e., the structural units derived from a (meth)acrylic acid alkyl ester may consist solely of structural units derived from a (meth)acrylic acid alkyl ester in which the carbon number of the alkyl group derived from the alcohol is 1 to 4.

[0016] Examples of (meth)acrylic acid alkyl esters in which the alcohol-derived alkyl group has 1 to 4 carbon atoms include (meth)acrylic acid alkyl esters obtained by dehydration condensation of (meth)acrylic acid and an alcohol having a linear or branched alkyl group having 1 to 4 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, and isobutyl (meth)acrylate. Of these, from the viewpoint of increasing the polarity of the acrylic copolymer, (meth)acrylic acid alkyl esters in which the alcohol-derived alkyl group has 1 to 2 carbon atoms are preferred. That is, the structural units derived from the (meth)acrylic acid alkyl esters preferably include structural units derived from (meth)acrylic acid alkyl esters in which the alcohol-derived alkyl group has 1 to 2 carbon atoms.

[0017] The preferred lower limit of the content of the structural units derived from the (meth)acrylic acid alkyl ester in which the alcohol-derived alkyl group has 1 to 2 carbon atoms is 10% by mass, and the preferred upper limit is 80% by mass. When the content of the structural units derived from the (meth)acrylic acid alkyl ester in which the alcohol-derived alkyl group has 1 to 2 carbon atoms is 10% by mass or more, the polarity of the acrylic copolymer is increased, thereby further increasing the cohesive strength of the pressure-sensitive adhesive layer, and as a result, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. In particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in high-temperature environments, thereby improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention in high-temperature environments. When the content of the structural units derived from the (meth)acrylic acid alkyl ester in which the alcohol-derived alkyl group has 1 to 2 carbon atoms is 80% by mass or less, the glass transition temperature (described later) of the acrylic copolymer can be easily adjusted to an appropriate range, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention. The content of structural units derived from the alkyl (meth)acrylate ester in which the alkyl group derived from the alcohol has 1 or more and 2 or less carbon atoms is more preferably 30% by mass, more preferably 70% by mass, even more preferably 45% by mass, and even more preferably 60% by mass.

[0018] The structural unit derived from the alkyl (meth)acrylate may have a structural unit derived from an alkyl (meth)acrylate other than the structural unit derived from the alkyl (meth)acrylate in which the alkyl group derived from the alcohol has 1 or more and 4 or less carbon atoms.

[0019] In the pressure-sensitive adhesive tape of the second invention, the content of the structural units derived from the (meth)acrylic acid alkyl ester in the acrylic copolymer has a lower limit of 50% by mass and an upper limit of 90% by mass. Furthermore, in the pressure-sensitive adhesive tape of the first invention, the content of the structural units derived from the (meth)acrylic acid alkyl ester in the acrylic copolymer is preferably 50% by mass and 90% by mass. By having the content of the structural units derived from the (meth)acrylic acid alkyl ester within the above range, the pressure-sensitive adhesive layer can achieve both sufficient flexibility and cohesive strength to exert its adhesive strength. In the pressure-sensitive adhesive tape of the second invention, the content of the structural units derived from the (meth)acrylic acid alkyl ester is preferably 60% by mass and 80% by mass, more preferably 65% ​​by mass and 75% by mass. In the pressure-sensitive adhesive tape of the present invention 1, the content of the structural units derived from the alkyl (meth)acrylate is more preferably 60% by mass in lower limit, more preferably 80% by mass in upper limit, even more preferably 65% ​​by mass in lower limit, and even more preferably 75% by mass in upper limit.

[0020] In the pressure-sensitive adhesive tape of the second aspect of the present invention, the acrylic copolymer has structural units derived from an olefin copolymer having a terminal polymerizable unsaturated double bond. Furthermore, in the pressure-sensitive adhesive tape of the first aspect of the present invention, the acrylic copolymer preferably has structural units derived from an olefin copolymer having a terminal polymerizable unsaturated double bond. When the acrylic copolymer has structural units derived from an olefin copolymer having a terminal polymerizable unsaturated double bond, the structural units derived from the olefin copolymer having a terminal polymerizable unsaturated double bond aggregate through interaction, forming a structure in which pseudo-crosslinking points are formed. When the acrylic copolymer has such a structure, the pressure-sensitive adhesive layer exhibits hard properties like a crosslinked pressure-sensitive adhesive layer when strain is small, improving holding power. On the other hand, when peel stress is applied and strain increases, the pseudo-crosslinking breaks, causing the molecules of the acrylic copolymer to stretch, resulting in the pressure-sensitive adhesive layer exhibiting high flexibility and improving adhesive power. In other words, when the acrylic copolymer has structural units derived from an olefin copolymer having a terminal polymerizable unsaturated double bond, the adhesive power and holding power of the pressure-sensitive adhesive layer are improved.

[0021] The olefin copolymer having a terminal polymerizable unsaturated double bond may have a polymerizable unsaturated double bond at one terminal or at both terminals. Among them, an olefin copolymer having a terminal polymerizable unsaturated double bond is preferred from the viewpoint of facilitating the formation of an appropriate number of pseudo-crosslinks.

[0022] Examples of the olefin copolymer having a polymerizable unsaturated double bond at its terminal include ethylene-butylene copolymers, ethylene-propylene copolymers, ethylene polymers, propylene polymers, butylene polymers, etc., which have a group having a polymerizable unsaturated double bond at one or both terminals. These olefin copolymers having a polymerizable unsaturated double bond at their terminals may be used alone or in combination of two or more.

[0023] Examples of the group having a polymerizable unsaturated double bond include a (meth)acryloyl group, a vinyl ether group, and a styryl group. Among these, a (meth)acryloyl group is preferred because of its excellent copolymerizability with the (meth)acrylic acid alkyl ester. In this specification, "(meth)acryloyl" means acryloyl or methacryloyl.

[0024] Examples of olefin copolymers having a (meth)acryloyl group at their termini include an ethylene macromonomer having a (meth)acryloyl group at one terminus, a propylene macromonomer having a (meth)acryloyl group at one terminus, an ethylene-butylene macromonomer having a (meth)acryloyl group at one terminus, and an ethylene-propylene macromonomer having a (meth)acryloyl group at one terminus. Of these, an ethylene-butylene macromonomer having a (meth)acryloyl group at one terminus and an ethylene-propylene macromonomer having a (meth)acryloyl group at one terminus are preferred, as they make it easier to satisfy the glass transition temperature described below and further improve the adhesive strength of the pressure-sensitive adhesive layer. In this specification, the term "macromonomer" refers to a monomer having a polymerizable functional group and a weight-average molecular weight of approximately 1,000 to 100,000.

[0025] In the acrylic copolymer, the content of the structural units derived from the olefin copolymer having a terminal polymerizable unsaturated double bond is preferably 5% by mass at the lower limit, and preferably 50% by mass at the upper limit.When the content of the structural units derived from the olefin copolymer having a terminal polymerizable unsaturated double bond is 5% by mass or more, the acrylic copolymer forms an appropriate number of pseudo-crosslinks, thereby further improving the adhesive strength and holding power of the pressure-sensitive adhesive layer.When the content of the structural units derived from the olefin copolymer having a terminal polymerizable unsaturated double bond is 50% by mass or less, the cohesive failure of the pressure-sensitive adhesive layer can be further suppressed.The content of the structural units derived from the olefin copolymer having a terminal polymerizable unsaturated double bond is more preferably 8% by mass at the lower limit, even more preferably 10% by mass at the lower limit, more preferably 30% by mass at the upper limit, even more preferably 27% by mass at the upper limit, and particularly preferably 25% by mass at the upper limit.

[0026] In the pressure-sensitive adhesive tape of the second invention, the acrylic copolymer has a structural unit derived from a polar functional group-containing monomer. Furthermore, in the pressure-sensitive adhesive tape of the first invention, the acrylic copolymer preferably has a structural unit derived from a polar functional group-containing monomer. When the acrylic copolymer has a structural unit derived from the polar functional group-containing monomer, the polarity of the acrylic copolymer increases, thereby increasing the cohesive strength of the pressure-sensitive adhesive layer and, as a result, improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention. In particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in high-temperature environments, thereby improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention in high-temperature environments. Furthermore, when the pressure-sensitive adhesive layer contains a crosslinking agent described below, the acrylic copolymer is crosslinked via the crosslinking agent, thereby improving the adhesive strength and holding power of the pressure-sensitive adhesive layer. By adjusting the degree of crosslinking, the gel fraction of the pressure-sensitive adhesive layer described below can be adjusted within an appropriate range.

[0027] Examples of the polar functional group-containing monomer include a carboxy group-containing monomer, a hydroxy group-containing monomer, an amide group-containing monomer, and an amino group-containing monomer. From the viewpoint of further improving the adhesive strength and holding power of the pressure-sensitive adhesive layer, the polar functional group-containing monomer preferably includes at least one selected from the group consisting of a carboxy group-containing monomer and a hydroxy group-containing monomer. These polar functional group-containing monomers may be used alone or in combination of two or more.

[0028] Examples of the carboxy group-containing monomer include unsaturated carboxylic acids such as (meth)acrylic acid, (meth)acryloylacetic acid, (meth)acryloylpropionic acid, (meth)acryloylbutyric acid, (meth)acryloylpentanoic acid, crotonic acid, maleic acid, fumaric acid, citraconic acid, mesaconic acid, and itaconic acid.

[0029] Examples of the hydroxyl group-containing monomer include 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate.

[0030] Examples of the amide group-containing monomer include N-vinyl-2-pyrrolidone, (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N-isopropyl(meth)acrylamide.

[0031] Examples of the amino group-containing monomer include (meth)acryloylmorpholine, 2-dimethylaminoethyl (meth)acrylate, and 2-diethylaminoethyl (meth)acrylate.

[0032] In the pressure-sensitive adhesive tape of the second invention, the lower limit of the content of the structural units derived from the polar functional group-containing monomer in the acrylic copolymer is 3% by mass, and the upper limit is 15% by mass. Furthermore, in the pressure-sensitive adhesive tape of the first invention, the preferred lower limit of the content of the structural units derived from the polar functional group-containing monomer in the acrylic copolymer is 3% by mass, and the preferred upper limit is 15% by mass. When the content of the structural units derived from the polar functional group-containing monomer is 3% by mass or more, the polarity of the acrylic copolymer increases, thereby increasing the cohesive strength of the pressure-sensitive adhesive layer, and as a result, improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention. In particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in high-temperature environments, thereby improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention in high-temperature environments. When the content of the structural units derived from the polar functional group-containing monomer is 15% by mass or less, the pressure-sensitive adhesive layer can be prevented from becoming too hard, thereby improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention. In the pressure-sensitive adhesive tape of invention 2, the content of the structural unit derived from the polar functional group-containing monomer is preferably 4% by mass at the lower limit and 10% by mass at the upper limit, more preferably 5% by mass at the lower limit and 7% by mass at the upper limit. In the pressure-sensitive adhesive tape of invention 1, the content of the structural unit derived from the polar functional group-containing monomer is more preferably 4% by mass at the lower limit and 10% by mass at the upper limit, still more preferably 5% by mass at the lower limit and 7% by mass at the upper limit.

[0033] The acrylic copolymer may have a constituent unit derived from a monomer other than the constituent unit derived from the alkyl (meth)acrylate, the constituent unit derived from the olefin copolymer having a terminal polymerizable unsaturated double bond, and the constituent unit derived from the polar functional group-containing monomer.

[0034] The glass transition temperature (Tg) of the acrylic copolymer is preferably in the range of -100°C or higher and 200°C or lower, with a more preferred upper limit of -20°C. When the glass transition temperature of the acrylic copolymer is -20°C or lower, the molecules of the acrylic copolymer are more likely to stretch, thereby further improving the adhesive strength of the pressure-sensitive adhesive layer. A more preferred upper limit of the glass transition temperature of the acrylic copolymer is -30°C, and an especially preferred upper limit is -35°C. Furthermore, when the pressure-sensitive adhesive layer contains a plurality of acrylic copolymers, it is preferred that the glass transition temperatures of all of the acrylic copolymers are -20°C or lower. The glass transition temperature of the acrylic copolymer can be measured by differential scanning calorimetry. More specifically, the glass transition temperature of the acrylic copolymer can be measured in a nitrogen atmosphere (nitrogen flow, flow rate 50 mL / min) using a differential scanning calorimeter (manufactured by Seiko Instruments Inc., "220C" or the like) according to a method in accordance with JIS K6240:2011 under conditions of a measurement temperature of -100°C to 200°C and a temperature rise rate of 10°C / min.

[0035] The glass transition temperature of the acrylic copolymer can be adjusted by changing the type and content of the monomers that are raw materials for the acrylic copolymer.

[0036] In the pressure-sensitive adhesive tape of the second invention, the acrylic copolymer has a weight-average molecular weight (Mw) of 750,000 or more and less than 1,500,000. Furthermore, in the pressure-sensitive adhesive tape of the first invention, the acrylic copolymer preferably has a weight-average molecular weight (Mw) of 750,000 or more and less than 1,500,000. When the weight-average molecular weight of the acrylic copolymer is 750,000 or more, the cohesive strength of the pressure-sensitive adhesive layer is increased, thereby improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention. In particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in a high-temperature environment, thereby improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention in a high-temperature environment. When the weight-average molecular weight of the acrylic copolymer is less than 1,500,000, the pressure-sensitive adhesive layer can be prevented from becoming too hard, thereby improving the initial adhesive strength of the pressure-sensitive adhesive layer. In the pressure-sensitive adhesive tape of the second invention, the preferred lower limit of the weight-average molecular weight of the acrylic copolymer is 800,000, and the preferred upper limit is 1,400,000, more preferably 900,000, and more preferably 1,200,000. In the pressure-sensitive adhesive tape of the first invention, the weight-average molecular weight of the acrylic copolymer preferably has a lower limit of 800,000 and an upper limit of 1,400,000, an even more preferred lower limit of 900,000 and an even more preferred upper limit of 1,200,000.

[0037] The ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the acrylic copolymer (polydispersity: Mw / Mn) is preferably 1.0 at its lower limit and 6.0 at its upper limit. The polydispersity of the acrylic copolymer within the above range further improves the adhesive strength and holding power of the pressure-sensitive adhesive layer. The polydispersity of the acrylic copolymer is more preferably 1.2 at its lower limit and 5.0 at its upper limit, still more preferably 1.5 at its lower limit and 4.5 at its upper limit.

[0038] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) refer to the weight average molecular weight measured in gel permeation chromatography (GPC) in terms of standard polystyrene. Specifically, the acrylic copolymer is diluted 50 times with tetrahydrofuran (THF), and the diluted solution is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate is supplied to a gel permeation chromatograph (Waters, "2690 Separations Model", etc.), and GPC measurement is performed under conditions of a sample flow rate of 1 mL / min and a column temperature of 40 ° C., and the polystyrene-equivalent molecular weight of the acrylic copolymer is measured to determine the weight average molecular weight (Mw) and number average molecular weight (Mn). As the column, for example, a GPC KF-806L (Showa Denko KK) or the like is used, and as the detector, for example, a differential refractometer or the like can be used. Furthermore, the polydispersity (Mw / Mn) can be obtained by using the weight average molecular weight (Mw) and number average molecular weight (Mn) thus obtained.

[0039] Examples of methods for adjusting the weight average molecular weight of the acrylic copolymer include a method of changing the polymerization temperature, a method of changing the polymerization time, a method of changing the type of solvent used in polymerization, a method of changing the type of monomer, a method of changing the concentration of the monomer, and a method of adding a chain transfer agent.

[0040] The preferred lower limit of the content of the acrylic copolymer in the pressure-sensitive adhesive layer is 70% by mass. When the content of the acrylic copolymer is 70% by mass or more, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. Although the content of the acrylic copolymer may be 100% by mass, a preferred upper limit is 99% by mass, and a more preferred upper limit is 98% by mass, from the viewpoint that the cohesive strength of the pressure-sensitive adhesive layer can be further increased by adding a silane coupling agent or a crosslinking agent, which will be described later, to the pressure-sensitive adhesive layer.

[0041] The polymerization method for synthesizing the (meth)acrylic copolymer may be a conventionally known method in which a raw material monomer mixture is subjected to a radical reaction in the presence of a polymerization initiator, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. Among these, solution polymerization is preferred because of its ease of synthesis.

[0042] When solution polymerization is used as the polymerization method, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, diethyl ether, etc. These reaction solvents may be used alone or in combination of two or more.

[0043] Examples of the polymerization initiator include organic peroxides and azo compounds. Examples of the 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 the azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination of two or more.

[0044] The pressure-sensitive adhesive layer preferably further contains a silane coupling agent. By containing the silane coupling agent in the pressure-sensitive adhesive layer, a chemical bond is formed between the adherend and the pressure-sensitive adhesive layer through a condensation reaction between hydroxyl groups and silanol groups on the adherend surface, and the pressure-sensitive adhesive layer can maintain sufficient interfacial interaction to exert its adhesive strength, particularly even in high-temperature environments. As a result, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved in high-temperature environments. The effect of containing the silane coupling agent in improving adhesive strength is particularly significant when the adherend is an adherend having many hydroxyl groups on the surface, such as glass.

[0045] The silane coupling agent preferably has a reactive moiety that forms a chemical bond with the acrylic copolymer, since it is desirable to form a chemical bond with the acrylic copolymer. Examples of the reactive moiety include an epoxy group, a functional group having a carbon-carbon double bond (such as a vinyl group or a (meth)acryloyl group), an amino group, and a mercapto group. Among these, an epoxy group is preferred from the viewpoint of excellent reactivity. In this specification, a carbon-carbon double bond contained in an aromatic ring is not included in the carbon-carbon double bond in the functional group having a carbon-carbon double bond.

[0046] Examples of the silane coupling agent having the reactive site include vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethylmethoxysilane, N-(2-aminoethyl)3-aminopropyltriethoxysilane, N-(2-aminoethyl)3-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, mercaptobutyltrimethoxysilane, and γ-mercaptopropylmethyldimethoxysilane. Among these, γ-glycidoxypropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane are preferred from the viewpoint of more easily improving the adhesive strength of the resulting pressure-sensitive adhesive tape. These silane coupling agents may be used alone or in combination of two or more.

[0047] The content of the silane coupling agent relative to 100 parts by mass of the acrylic copolymer is preferably 0.1 parts by mass at the lower limit and 3.0 parts by mass at the upper limit.When the content of the silane coupling agent is 0.1 parts by mass or more, a chemical bond is formed between the adherend and the pressure-sensitive adhesive layer, and in particular, sufficient interfacial interaction can be maintained so that the pressure-sensitive adhesive layer can exert its adhesive strength even under high-temperature conditions, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention under high-temperature conditions.When the content of the silane coupling agent is 3.0 parts by mass or less, the pressure-sensitive adhesive layer can be prevented from becoming too hard, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention.A more preferred lower limit of the content of the silane coupling agent is 0.3 parts by mass, a more preferred upper limit is 2.0 parts by mass, an even more preferred lower limit is 0.5 parts by mass, and an even more preferred upper limit is 1.0 parts by mass.

[0048] The pressure-sensitive adhesive layer preferably further contains a crosslinking agent. By containing a crosslinking agent in the pressure-sensitive adhesive layer, a crosslinked structure is formed in which the acrylic copolymer is crosslinked via the crosslinking agent, thereby further increasing the cohesive strength of the pressure-sensitive adhesive layer, and as a result, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. In particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in a high-temperature environment, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention in a high-temperature environment. By adjusting the degree of crosslinking at this time, the gel fraction of the pressure-sensitive adhesive layer, which will be described later, can be adjusted within an appropriate range.

[0049] Examples of the crosslinking agent include epoxy-based crosslinking agents, isocyanate-based crosslinking agents, etc. Among these, isocyanate-based crosslinking agents are preferred because they make it easier to adjust the gel fraction of the pressure-sensitive adhesive layer (described below) within an appropriate range and further improve the adhesive strength and holding power of the pressure-sensitive adhesive tape of the present invention.

[0050] The preferred lower limit of the content of the crosslinking agent relative to 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 content of the crosslinking agent within this range, it becomes easier to adjust the gel fraction of the pressure-sensitive adhesive layer (described later) within an appropriate range, and the adhesive strength and holding power of the pressure-sensitive adhesive tape are further improved. The more preferred lower limit of the content of the crosslinking agent is 0.1 parts by mass, and the more preferred upper limit is 3.0 parts by mass.

[0051] The pressure-sensitive adhesive layer may further contain a tackifier resin. When the pressure-sensitive adhesive layer contains a tackifier resin, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved.

[0052] Examples of the tackifier resin include terpene phenol resins, rosin resins, xylene resins, terpene resins, and petroleum resins. Among these, from the viewpoint of relatively high polarity and enhanced interaction between the pressure-sensitive adhesive layer and the adherend, it is preferable that the tackifier resin be at least one selected from the group consisting of terpene phenol resins, rosin resins, and xylene resins. These tackifier resins may be used alone or in combination of two or more.

[0053] Examples of the terpene phenol resins include YS Polystar G150 and YS Polystar G125 (both manufactured by Yasuhara Chemical Co., Ltd.). Examples of the rosin resins include Superester A-125 (manufactured by Arakawa Chemical Industries, Ltd.). Examples of the xylene resins include GHP-125 and GHP-150 (both manufactured by Fudow Co., Ltd.).

[0054] The preferred upper limit of the content of the tackifier resin relative to 100 parts by mass of the acrylic copolymer is 20 parts by mass. By keeping the content of the tackifier resin at 20 parts by mass or less, it is possible to prevent a decrease in adhesive strength due to bleeding of low molecular weight components in a high temperature environment. The more preferred upper limit of the content of the tackifier resin is 10 parts by mass.

[0055] The pressure-sensitive adhesive layer may contain conventionally known fine particles and additives, such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers, as needed.

[0056] The preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 10% by mass, and the preferred upper limit is 85% by mass. A gel fraction of the pressure-sensitive adhesive layer of 10% by mass or more further enhances the cohesive strength of the pressure-sensitive adhesive layer, resulting in superior adhesive strength of the pressure-sensitive adhesive tape of the present invention. In particular, the pressure-sensitive adhesive layer can maintain sufficient cohesive strength to exert its adhesive strength even in high-temperature environments, resulting in superior adhesive strength of the pressure-sensitive adhesive tape of the present invention. A gel fraction of the pressure-sensitive adhesive layer of 85% by mass or less can prevent the pressure-sensitive adhesive layer from becoming too hard, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape. The preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 20% by mass, and the preferred upper limit is 65% by mass, more preferably 30% by mass, and more preferably 50% by mass. The gel fraction of the pressure-sensitive adhesive layer can be measured by the following method, etc. Specifically, a test piece is prepared by cutting the pressure-sensitive adhesive tape into a 50 mm x 100 mm planar rectangular shape. The test piece is immersed in tetrahydrofuran (THF) at 23°C for 24 hours, then removed from the tetrahydrofuran and dried at 110°C for 1 hour. The mass of the test piece after drying is measured, and the gel fraction is calculated using the following formula (1). Note that no release film for protecting the adhesive layer is laminated on the test piece. In addition, when the adhesive tape does not have a substrate, W ０ = 0. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １ -W ０ ) (1) (W ０ : Mass of the substrate, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0057] Methods for adjusting the gel fraction of the pressure-sensitive adhesive layer include a method for adjusting the content ratio of structural units derived from polar functional group-containing monomers in the acrylic copolymer, and a method for adjusting the type and content of the tackifier resin or the crosslinking agent.

[0058] The preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 5 μm, and the preferred upper limit is 200 μm. When the thickness of the pressure-sensitive adhesive layer is 5 μm or more, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. When the thickness of the pressure-sensitive adhesive layer is 200 μm or less, deformation of the pressure-sensitive adhesive tape of the present invention is suppressed, and the adhesive strength at high temperatures is further improved. The more preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 10 μm, and the more preferred upper limit is 100 μm, and the even more preferred lower limit is 25 μm, and the even more preferred upper limit is 50 μm. In this specification, the thickness can be measured using a dial thickness meter (such as the "ABS Digimatic Indicator" manufactured by Mitutoyo Corporation).

[0059] The pressure-sensitive adhesive tape of the present invention may be a non-support type that does not have a substrate, or may be a support type that has a substrate. In particular, the pressure-sensitive adhesive tape of the present invention preferably has a substrate. When the pressure-sensitive adhesive tape of the present invention has a substrate, it becomes easy to handle.

[0060] When the pressure-sensitive adhesive tape of the present invention has a substrate, it may be a single-sided pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer on one side of the substrate, or a double-sided pressure-sensitive adhesive tape having the pressure-sensitive adhesive layers on both sides of the substrate. Among these, a double-sided pressure-sensitive adhesive tape having the pressure-sensitive adhesive layers on both sides of the substrate is preferred from the viewpoint of handleability.

[0061] Examples of the substrate include nonwoven fabrics and film-like materials. Examples of the film-like materials include polyester (PE) films, polyimide (PI) films, polyamide (PA) films, polyether ether ketone (PEEK) films, polyphenylene ether (PPE) films, polyphenylene sulfide (PPS) films, and polyethylene terephthalate (PET) films. From the viewpoint of heat resistance, the substrate is preferably at least one selected from the group consisting of nonwoven fabrics, polyester films, polyimide films, polyamide films, polyether ether ketone films, polyphenylene ether films, and polyphenylene sulfide films.

[0062] The preferred lower limit of the thickness of the substrate is 10 μm, and the preferred upper limit is 150 μm. When the thickness of the substrate is 10 μm or more, the pressure-sensitive adhesive tape has appropriate stiffness and is easier to handle. When the thickness of the substrate is 150 μm or less, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The more preferred lower limit of the thickness of the substrate is 20 μm, and the more preferred upper limit is 100 μm, and the even more preferred lower limit is 40 μm, and the even more preferred upper limit is 75 μm.

[0063] The pressure-sensitive adhesive tape of the present invention may further have other layers as long as the effects of the present invention are not impaired.

[0064] The method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited, and conventionally known methods can be used. For example, first, the (meth)acrylic acid alkyl ester, the polar functional group-containing monomer, the olefin-based copolymer having a terminal polymerizable unsaturated double bond, and, if necessary, other monomers are copolymerized by a conventional method to obtain the acrylic copolymer. Next, a pressure-sensitive adhesive solution containing the obtained acrylic copolymer and, if necessary, a silane coupling agent, a crosslinking agent, a tackifying resin, and other additives is applied to the release-treated surface of a release-treated film and dried to produce the pressure-sensitive adhesive tape. The pressure-sensitive adhesive tape produced by the above-mentioned method can also be laminated to a substrate as a pressure-sensitive adhesive layer to produce a support-type pressure-sensitive adhesive tape.

[0065] The preferred lower limit of the overall thickness of the pressure-sensitive adhesive tape of the present invention is 50 μm, and the preferred upper limit is 200 μm. When the overall thickness of the pressure-sensitive adhesive tape of the present invention is 50 μm or more, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. When the overall thickness of the pressure-sensitive adhesive tape of the present invention is 200 μm or less, deformation of the pressure-sensitive adhesive tape of the present invention is suppressed, and the adhesive strength at high temperatures is further improved. The more preferred lower limit of the overall thickness of the pressure-sensitive adhesive tape of the present invention is 75 μm, the more preferred upper limit is 175 μm, the even more preferred lower limit is 100 μm, and the even more preferred upper limit is 150 μm.

[0066] The use of the pressure-sensitive adhesive tape of the present invention is not particularly limited, but since it has excellent adhesive strength even in high-temperature environments, it is preferably used for fixing electronic device components or vehicle-mounted components. Specifically, it can be preferably used for fixing, for example, cover panels that protect the surfaces of electronic devices, battery packs, fuel cell cells, vehicle-mounted panels, vehicle-mounted exterior components, etc.

[0067] The pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape of the present invention can be obtained by using a pressure-sensitive adhesive composition.

[0013] The present invention also provides a pressure-sensitive adhesive composition comprising an acrylic copolymer having structural units derived from an alkyl (meth)acrylate ester, structural units derived from an olefin copolymer having a terminal polymerizable unsaturated double bond, and structural units derived from a polar functional group-containing monomer, and an organic solvent, wherein the structural units derived from the alkyl (meth)acrylate include structural units derived from an alkyl (meth)acrylate ester in which the alkyl group derived from an alcohol has 1 to 4 carbon atoms, the content of structural units derived from an alkyl (meth)acrylate ester in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms is 50 to 100 mass%, the content of structural units derived from the alkyl (meth)acrylate ester in the acrylic copolymer is 50 to 90 mass%, the content of structural units derived from the alkyl (meth)acrylate ester in the acrylic copolymer is 3 to 15 mass%, and the weight average molecular weight of the acrylic copolymer is 750,000 to less than 1,500,000. The acrylic copolymer used in the pressure-sensitive adhesive composition of the present invention is the same as the acrylic copolymer used in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the second invention described above.

[0068] The pressure-sensitive adhesive composition of the present invention contains an organic solvent. By containing an organic solvent, the pressure-sensitive adhesive composition of the present invention can be easily applied.

[0069] Specific examples of the organic solvent include benzene, toluene, xylene, tetralin, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, and isopentyl acetate.

[0070] The pressure-sensitive adhesive composition of the present invention preferably further contains a silane coupling agent. Examples of the silane coupling agent include the same silane coupling agents as those used in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention.

[0071] The pressure-sensitive adhesive composition of the present invention preferably further contains a crosslinking agent. Examples of the crosslinking agent include the same crosslinking agents as those used in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention.

[0072] The pressure-sensitive adhesive composition of the present invention may further contain a tackifier resin. The tackifier resin is, for example, the same as the tackifier resin used in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention described above.

[0073] The pressure-sensitive adhesive composition of the present invention may contain conventionally known fine particles and additives, such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers, as needed.

[0074] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape having excellent adhesive strength in a high-temperature environment. Also, according to the present invention, it is possible to provide a pressure-sensitive adhesive composition having excellent adhesive strength in a high-temperature environment.

[0075] The following examples further illustrate aspects of the present invention, but the present invention is not limited to these examples.

[0076] (Synthesis of Acrylic Copolymers A to X) Ethyl acetate and the monomers shown in Table 1 were added to a reactor equipped with a thermometer, a stirrer, and a cooling tube, and the reactor was then heated to initiate reflux. Subsequently, 0.01 parts by mass of 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane was added as a polymerization initiator to the reactor, and polymerization was initiated under reflux. Thereafter, 0.01 parts by mass of 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane were added one hour and two hours after the start of polymerization, and further 0.05 parts by mass of t-hexylperoxypivalate was added four hours after the start of polymerization to continue the polymerization reaction. The polymerization reaction was then carried out for a total of eight hours from the start of polymerization, yielding ethyl acetate solutions containing acrylic copolymers A to X. The molecular weight of each acrylic copolymer was adjusted by increasing or decreasing the amount of ethyl acetate to control the reaction solid content. In addition, each obtained acrylic copolymer was diluted 50 times with tetrahydrofuran (THF), and the diluted solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). 20 μL of the obtained filtrate was supplied as a sample to a gel permeation chromatograph (Waters, "2690 Separations Model"), and GPC measurement was 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 was measured, and the weight average molecular weight (Mw) and number average molecular weight (Mn) were determined, and the polydispersity (Mw / Mn) was obtained. A GPC KF-806L (Showa Denko KK) was used as the column, and a differential refractometer was used as the detector. The results are shown in Table 1.

[0077] The structural unit monomers shown in Table 1 are as follows: BA: n-butyl acrylate MA: methyl acrylate 2EHA: 2-ethylhexyl acrylate EBm: ethylene-butylene macromonomer (olefin polymer having a methacryloyl group at one end, manufactured by Kraton Polymer Japan, "HPVM-L1253", weight average molecular weight 7000) AAc: acrylic acid 4HBA: 4-hydroxybutyl acrylate

[0078]

[0079] (Examples 1 to 37, 39, 40, Comparative Examples 1 to 9) (1) Preparation of Pressure-Sensitive Adhesive Compositions and Pressure-Sensitive Adhesive Tapes Each component shown in Tables 2 to 5 was added to an ethyl acetate solution of an acrylic copolymer shown in Table 1 to obtain a solution containing a pressure-sensitive adhesive composition. Furthermore, the solution containing the pressure-sensitive adhesive composition was thoroughly stirred to obtain a pressure-sensitive adhesive solution. The resulting pressure-sensitive adhesive solution was applied to the release-treated surface of a 50 μm-thick polyethylene terephthalate (PET) film, one side of which had been release-treated, and dried at 110°C for 5 minutes to produce a laminate sheet having a pressure-sensitive adhesive layer of the thickness shown in Tables 2 to 5 on the release-treated surface of the PET film. A substrate shown in Tables 2 to 5 was prepared, and the resulting laminate sheet was attached to one side of the substrate with the pressure-sensitive adhesive layer facing the substrate. Furthermore, a similar laminate sheet was attached to the other side of the substrate with the pressure-sensitive adhesive layer facing the substrate, and the resulting laminate sheet was aged for 48 hours in an environment of 40°C to obtain a pressure-sensitive adhesive tape having pressure-sensitive adhesive layers of the same composition and thickness on both sides of the substrate.

[0080] (2) Gel Fraction of Pressure-Sensitive Adhesive Layer The obtained pressure-sensitive adhesive tape was cut into a flat rectangular shape of 50 mm x 100 mm to prepare a test specimen. The test specimen was immersed in tetrahydrofuran (THF) at 23°C for 24 hours, then removed from the tetrahydrofuran and dried at 110°C for 1 hour. The mass of the test specimen after drying was measured, and the gel fraction was calculated using the following formula (1). Note that no release film for protecting the pressure-sensitive adhesive layer was laminated on the test specimen. The results are shown in Tables 2 to 5. Gel fraction (mass%) = 100 x (W ２ -W ０ ) / (W １ -W ０ ) (1) (W ０ : Mass of the substrate, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0081] (3) Shear Storage Modulus of the Pressure-Sensitive Adhesive Layer at 150°C and Loss Tangent of the Pressure-Sensitive Adhesive Layer at 150°C The pressure-sensitive adhesive layers of the laminated sheets prepared in the above-mentioned "(1) Preparation of Pressure-Sensitive Adhesive Tape" were stacked to prepare a measurement sample consisting of only the pressure-sensitive adhesive layer with a thickness of 500 μm. Dynamic viscoelasticity measurements were performed on the obtained measurement sample using a dynamic viscoelasticity measuring device (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") under conditions of a nitrogen atmosphere, shear direction, frequency of 1 Hz, heating rate of 5°C / min, temperature range of -100°C to 200°C, and strain of 0.08%, and the dynamic viscoelasticity spectrum was measured to obtain the shear storage modulus (Pa) of the pressure-sensitive adhesive layer at 150°C and the loss tangent of the pressure-sensitive adhesive layer at 150°C. The results are shown in Tables 2 to 5.

[0082] (Example 38) (1) Preparation of Pressure-Sensitive Adhesive Composition and Pressure-Sensitive Adhesive Tape To an ethyl acetate solution of acrylic copolymer K shown in Table 1, each of the components shown in Table 4 was added to obtain a solution containing a pressure-sensitive adhesive composition. Furthermore, the solution containing the pressure-sensitive adhesive composition was thoroughly stirred to obtain a pressure-sensitive adhesive solution. Using the obtained pressure-sensitive adhesive solution, a laminate sheet having a 100 μm-thick pressure-sensitive adhesive layer was prepared in the same manner as in Examples 1 to 37, 39, and 40 and Comparative Examples 1 to 9. A 50 μm-thick PET film, one side of which had been release-treated, was then placed on the pressure-sensitive adhesive layer surface of the prepared laminate sheet, with the release-treated surface facing the laminate, to obtain a pressure-sensitive adhesive tape having no substrate.

[0083] (2) Gel Fraction of Pressure-Sensitive Adhesive Layer The gel fraction (mass%) of the pressure-sensitive adhesive layer was obtained in the same manner as in Examples 1 to 37, 39, and 40 and Comparative Examples 1 to 9. The gel fraction of the pressure-sensitive adhesive layer was calculated by using the formula (1) above, where W ０ = 0. The results are shown in Table 4.

[0084] (3) Shear storage modulus of pressure-sensitive adhesive layer at 150°C and loss tangent of pressure-sensitive adhesive layer at 150°C The shear storage modulus (Pa) of the pressure-sensitive adhesive layer at 150°C and the loss tangent of the pressure-sensitive adhesive layer at 150°C were obtained in the same manner as in Examples 1 to 37, 39, and 40 and Comparative Examples 1 to 9. The results are shown in Table 4.

[0085] <Evaluation> The pressure-sensitive adhesive tapes obtained in the Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 2 to 5.

[0086] (Adhesion strength under high temperature environment) The obtained pressure-sensitive adhesive tape was cut into a flat rectangular shape of 25 mm x 50 mm to prepare a test piece. Next, one release PET film of the obtained test piece was peeled off, and the test piece was bonded to a 0.1 mm thick SUS304 plate (SUS304 plate washed with ethanol and then wiped dry) by rolling a 2 kg hand roller back and forth once at a speed of 300 mm / min. Furthermore, the other release PET film was peeled off, and the test piece was bonded to a 0.1 mm thick SUS304 plate (SUS304 plate washed with ethanol and then wiped dry) by rolling a 2 kg hand roller back and forth once at a speed of 300 mm / min. Then, the test piece was left to stand at 23 ° C for 24 hours to obtain a measurement sample. For the obtained measurement sample, a T-peel test was performed in accordance with JIS K6854-3:1999 using a tensile tester (manufactured by A & D Co., Ltd., "RTI-1310") under conditions of 100 ° C. and a peel rate of 10 mm / min. The SUS304 plate (the surface to be measured) was peeled off in the vertical direction from the adhesive tape of the measurement sample, and the T-peel force against SUS at 100 ° C. was measured. If the obtained T-peel force against SUS at 100 ° C. was 20 N / 25 mm or more, it was marked "◎", if it was 15 N / 25 mm or more but less than 20 N / 25 mm, it was marked "○", if it was 10 N / 25 mm or more but less than 15 N / 25 mm, it was marked "△", and if it was less than 10 N / 25 mm, it was marked "x", and the adhesive strength of the adhesive tape in a high temperature environment was evaluated.

[0087] The substrates shown in Tables 2 to 5 are as follows: PEN film: polyethylene naphthalate film (Teonex, manufactured by Teijin Limited) PI film: polyimide film (Kapton, manufactured by DuPont-Toray Co., Ltd.) PEEK film: polyether ether ketone film (EXPEEK, manufactured by Kurabo Industries, Ltd.)

[0088]

[0089]

[0090]

[0091]

[0092] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape having excellent adhesive strength in a high-temperature environment. Also, according to the present invention, it is possible to provide a pressure-sensitive adhesive composition having excellent adhesive strength in a high-temperature environment.

Claims

1. An adhesive tape having an adhesive layer, The adhesive layer comprises an acrylic copolymer. The adhesive layer has a shear storage modulus of 8.0 × 10⁻¹⁶ at 150°C, as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz. ４ Pa or more 3.0×10 ５ The pressure is Pa or less, and the loss tangent (tanδ) at 150°C, measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz, is between 0.10 and 0.

40. An adhesive tape characterized by the following features.

2. The acrylic copolymer has constituent units derived from alkyl (meth)acrylate, The aforementioned structural unit derived from the alkyl (meth)acrylate includes a structural unit derived from the alkyl (meth)acrylate having 1 to 4 carbon atoms in the alcohol-derived alkyl group, In the constituent units derived from the alkyl (meth)acrylate, the content of constituent units derived from the alkyl (meth)acrylate, in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms, is 50% by mass or more and 100% by mass or less. The content of the constituent units derived from the alkyl (meth)acrylate in the acrylic copolymer is 50% by mass or more and 90% by mass or less. The adhesive tape according to claim 1.

3. The constituent unit derived from the (meth)acrylate alkyl ester includes a constituent unit derived from the (meth)acrylate alkyl ester having 1 to 2 carbon atoms in the alcohol-derived alkyl group, The content of the constituent units derived from the alkyl (meth)acrylate, in which the alkyl group derived from the alcohol has 1 to 2 carbon atoms, is 10% by mass or more and 80% by mass or less. The adhesive tape according to claim 2.

4. The acrylic copolymer has constituent units derived from a monomer containing a polar functional group, The content of constituent units derived from the polar functional group-containing monomer in the acrylic copolymer is 3% by mass or more and 15% by mass or less. The adhesive tape according to claim 1, 2, or 3.

5. The adhesive tape according to claim 4, wherein the constituent unit derived from the polar functional group-containing monomer comprises at least one constituent unit selected from the group consisting of constituent units derived from carboxyl group-containing monomers and constituent units derived from hydroxyl group-containing monomers.

6. The adhesive tape according to claim 1, 2, or 3, wherein the acrylic copolymer has constituent units derived from an olefin copolymer having polymerizable unsaturated double bonds at its terminals.

7. The adhesive tape according to claim 6, wherein the content of constituent units derived from an olefin copolymer having polymerizable unsaturated double bonds at its ends in the acrylic copolymer is 5% by mass or more and 50% by mass or less.

8. The adhesive tape according to claim 1, 2, or 3, wherein the acrylic copolymer has a weight-average molecular weight of 750,000 or more and less than 1,500,000.

9. The adhesive tape according to claim 1, 2, or 3, wherein the adhesive layer further contains a silane coupling agent.

10. The adhesive tape according to claim 9, wherein the content of the silane coupling agent is 0.1 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the acrylic copolymer.

11. The adhesive tape according to claim 1, 2, or 3, wherein the adhesive layer further contains a tackifying resin.

12. The adhesive tape according to claim 11, wherein the tackifying resin comprises at least one selected from the group consisting of terpene phenol resins, rosin resins, and xylene resins.

13. The adhesive tape according to claim 11, wherein the content of the tackifying resin is 20 parts by mass or less per 100 parts by mass of the acrylic copolymer.

14. The adhesive tape according to claim 1, 2, or 3, wherein the adhesive layer has a gel fraction of 10% by mass or more and 85% by mass or less.

15. The adhesive tape according to claim 1, 2, or 3, wherein the thickness of the adhesive layer is 5 μm or more and 200 μm or less.

16. The adhesive tape according to claim 1, 2, or 3, having a base material.

17. The adhesive tape according to claim 16, wherein the substrate comprises at least one selected from the group consisting of nonwoven fabric, polyester film, polyimide film, polyamide film, polyetheretherketone film, polyphenylene ether film, and polyphenylene sulfide film.

18. The adhesive tape according to claim 1, 2, or 3, wherein the total thickness of the adhesive tape is 50 μm or more and 200 μm or less.

19. The adhesive tape according to claim 1, 2, or 3, used for fixing electronic equipment components or in-vehicle components.

20. An adhesive tape having an adhesive layer, The adhesive layer contains a structural unit derived from an alkyl (meth)acrylate, a structural unit derived from an olefin copolymer having polymerizable unsaturated double bonds at its terminals, and a structural unit derived from a monomer containing polar functional groups. The aforementioned structural unit derived from the alkyl (meth)acrylate includes a structural unit derived from the alkyl (meth)acrylate having 1 to 4 carbon atoms in the alcohol-derived alkyl group, In the constituent units derived from the alkyl (meth)acrylate, the content of constituent units derived from the alkyl (meth)acrylate, in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms, is 50% by mass or more and 100% by mass or less. The content of the constituent units derived from the alkyl (meth)acrylate in the acrylic copolymer is 50% by mass or more and 90% by mass or less. The content of constituent units derived from the polar functional group-containing monomer in the acrylic copolymer is 3% by mass or more and 15% by mass or less. The aforementioned acrylic copolymer has a weight-average molecular weight of 750,000 or more and less than 1,500,000. An adhesive tape characterized by the following features.

21. The constituent unit derived from the (meth)acrylate alkyl ester includes a constituent unit derived from the (meth)acrylate alkyl ester having 1 to 2 carbon atoms in the alcohol-derived alkyl group, The content of the constituent units derived from the alkyl (meth)acrylate, in which the alkyl group derived from the alcohol has 1 to 2 carbon atoms, is 10% by mass or more and 80% by mass or less. The adhesive tape according to claim 20.

22. The adhesive tape according to claim 20 or 21, wherein the constituent unit derived from the polar functional group-containing monomer comprises at least one constituent unit selected from the group consisting of constituent units derived from carboxyl group-containing monomers and constituent units derived from hydroxyl group-containing monomers.

23. The adhesive tape according to claim 20 or 21, wherein the content of constituent units derived from an olefin copolymer having a polymerizable unsaturated double bond at its end in the acrylic copolymer is 5% by mass or more and 50% by mass or less.

24. The adhesive tape according to claim 20 or 21, wherein the adhesive layer further contains a silane coupling agent.

25. The adhesive tape according to claim 24, wherein the content of the silane coupling agent is 0.1 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the acrylic copolymer.

26. The adhesive tape according to claim 20 or 21, wherein the adhesive layer further contains a tackifying resin.

27. The adhesive tape according to claim 26, wherein the tackifying resin comprises at least one selected from the group consisting of terpene phenol resins, rosin resins, and xylene resins.

28. The adhesive tape according to claim 26, wherein the content of the tackifying resin is 20 parts by mass or less per 100 parts by mass of the acrylic copolymer.

29. The adhesive tape according to claim 20 or 21, wherein the adhesive layer has a gel fraction of 10% by mass or more and 85% by mass or less.

30. The adhesive tape according to claim 20 or 21, wherein the thickness of the adhesive layer is 5 μm or more and 200 μm or less.

31. The adhesive tape according to claim 20 or 21, having a base material.

32. The adhesive tape according to claim 31, wherein the substrate comprises at least one selected from the group consisting of nonwoven fabric, polyester film, polyimide film, polyamide film, polyetheretherketone film, polyphenylene ether film, and polyphenylene sulfide film.

33. The adhesive tape according to claim 20 or 21, wherein the total thickness of the adhesive tape is 50 μm or more and 200 μm or less.

34. The adhesive tape according to claim 20 or 21, used for fixing electronic equipment components or in-vehicle components.

35. An acrylic copolymer having structural units derived from alkyl (meth)acrylate ester, structural units derived from an olefin copolymer having polymerizable unsaturated double bonds at its termini, and structural units derived from a monomer containing polar functional groups, and an organic solvent, The aforementioned structural unit derived from the alkyl (meth)acrylate includes a structural unit derived from the alkyl (meth)acrylate having 1 to 4 carbon atoms in the alcohol-derived alkyl group, In the constituent units derived from the alkyl (meth)acrylate, the content of constituent units derived from the alkyl (meth)acrylate, in which the alkyl group derived from the alcohol has 1 to 4 carbon atoms, is 50% by mass or more and 100% by mass or less. The content of the constituent units derived from the alkyl (meth)acrylate in the acrylic copolymer is 50% by mass or more and 90% by mass or less. The content of constituent units derived from the polar functional group-containing monomer in the acrylic copolymer is 3% by mass or more and 15% by mass or less. The aforementioned acrylic copolymer has a weight-average molecular weight of 750,000 or more and less than 1,500,000. An adhesive composition characterized by the following features.

36. The constituent unit derived from the (meth)acrylate alkyl ester includes a constituent unit derived from the (meth)acrylate alkyl ester having 1 to 2 carbon atoms in the alcohol-derived alkyl group, The content of the constituent units derived from the alkyl (meth)acrylate, in which the alkyl group derived from the alcohol has 1 to 2 carbon atoms, is 10% by mass or more and 80% by mass or less. The adhesive composition according to claim 35.