Adhesive tape

Abstract

The purpose of the present invention is to provide an adhesive tape having excellent heat resistance and excellent impact resistance to various types of impact. The present invention is an adhesive tape having an adhesive layer formed using an adhesive composition, wherein the adhesive layer has a glass transition temperature of 0°C or higher as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz in a measurement temperature range of -40°C to 200°C, and the half-value width of a peak of the loss tangent of the adhesive layer as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz in a measurement temperature range of -40°C to 200°C is 38°C or higher.

Description

adhesive tape

[0001] The present invention relates to an adhesive tape.

[0002] Conventionally, pressure-sensitive adhesive tapes having a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition have been widely used to fix components in electronic devices, vehicles, houses, and building materials (e.g., Patent Documents 1 to 3). Specifically, for example, pressure-sensitive adhesive tapes are 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] In recent years, the physical properties required for adhesive tapes used to bond electronic device components have become more diverse due to the diversification of electronic device applications, thinner designs, smaller designs, etc. Frequently used electronic devices such as portable electronic devices are at risk of being subjected to impacts such as dropping, and therefore need to be resistant to damage even when subjected to impacts such as dropping, and therefore adhesive tapes used to fix internal components of such electronic devices are required to be impact resistant.

[0005] Conventionally, methods for improving the impact resistance of adhesive tapes have been used, such as lowering the glass transition temperature of the adhesive layer to improve its flexibility. However, in recent years, as electronic devices have become more powerful, temperatures tend to rise during use. Therefore, adhesive tapes used to secure components of such electronic devices are required to have better heat resistance. Therefore, methods for lowering the glass transition temperature of the adhesive layer have presented problems in terms of heat resistance. While there is also a method for improving the impact resistance of adhesive tapes by increasing the thickness of the adhesive layer, this method has the drawback of being inapplicable when securing components of thin electronic devices. Therefore, it has been difficult to obtain adhesive tapes that combine heat resistance and impact resistance.

[0006] Furthermore, since electronic devices that are used frequently, such as portable electronic devices, are expected to be used in a variety of ways, when an electronic device is subjected to an impact, various situations can be expected in which the impact occurs, such as the speed that indicates the behavior of the electronic device immediately before it is subjected to an impact such as a fall.

[0007] An object of the present invention is to provide an adhesive tape that has excellent heat resistance and excellent impact resistance against various types of impact.

[0008] Disclosure 1 is a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition, wherein the pressure-sensitive adhesive layer has a glass transition temperature of 0°C or higher as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and in a measurement temperature range of -40°C or higher and 200°C or lower, and wherein the pressure-sensitive adhesive layer has a half-width of a loss tangent peak of 38°C or higher as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and in a measurement temperature range of -40°C or higher and 200°C or lower. Disclosure 2 is a pressure-sensitive adhesive tape having a shear storage modulus at 80°C of 2.0 x 10 or higher as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and in a measurement temperature range of -40°C or higher and 200°C or lower. ４The pressure-sensitive adhesive tape of Disclosure 1 has a shear storage modulus of 0.25 MPa or more at 23°C and a loss tangent of 0.50 or more at 65°C. Disclosure 3 is the pressure-sensitive adhesive tape of Disclosure 1 or 2, wherein the pressure-sensitive adhesive layer has a shear storage modulus of 0.25 MPa or more at 23°C and a loss tangent of 0.50 or more at 65°C. Disclosure 4 is the pressure-sensitive adhesive tape of Disclosure 1, 2, or 3, wherein the pressure-sensitive adhesive composition contains a (meth)acrylic copolymer, the (meth)acrylic copolymer has structural units derived from an alkyl (meth)acrylate and structural units derived from a monomer having a crosslinkable functional group, and the (meth)acrylic copolymer has a content of the structural units derived from the monomer having a crosslinkable functional group of 0.01% by mass or more and 20% by mass or less. Disclosure 5 is the pressure-sensitive adhesive tape of Disclosure 4, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having an alkyl group with 7 to 10 carbon atoms, and the (meth)acrylic copolymer contains 45 mass% or more of structural units derived from the alkyl (meth)acrylate having an alkyl group with 7 to 10 carbon atoms. Disclosure 6 is the pressure-sensitive adhesive tape of Disclosure 4 or 5, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having a branched alkyl group, and the (meth)acrylic copolymer contains 45 mass% or more of structural units derived from the alkyl (meth)acrylate having a branched alkyl group. Disclosure 7 is the pressure-sensitive adhesive tape of Disclosure 4, 5, or 6, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having a boiling point of 200°C or higher. Disclosure 8 is the pressure-sensitive adhesive tape of Disclosure 4, 5, 6, or 7, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer. Disclosure 9 is the pressure-sensitive adhesive tape of Disclosure 4, 5, 6, 7, or 8, wherein the alkyl (meth)acrylate comprises 1-methylheptyl acrylate. Disclosure 10 is the pressure-sensitive adhesive tape of Disclosure 4, 5, 6, 7, 8, or 9, wherein the alkyl (meth)acrylate comprises n-heptyl (meth)acrylate.

[0023] Disclosure 11 is the pressure-sensitive adhesive tape of Disclosures 4, 5, 6, 7, 8, 9, or 10, wherein the monomer having a crosslinkable functional group comprises a hydroxyl group-containing monomer, and the (meth)acrylic copolymer has a content ratio of structural units derived from the hydroxyl group-containing monomer of 0.01% by mass or more and 2.0% by mass or less. Disclosure 12 is the pressure-sensitive adhesive tape of Disclosures 4, 5, 6, 7, 8, 9, 10, or 11, wherein the monomer having a crosslinkable functional group comprises a carboxyl group-containing monomer, and the (meth)acrylic copolymer has a content ratio of structural units derived from the carboxyl group-containing monomer of 0.1% by mass or more and 15% by mass or less. Disclosure 13 is the pressure-sensitive adhesive tape of Disclosures 4, 5, 6, 7, 8, 9, 10, 11, or 12, wherein the (meth)acrylic copolymer has at least one structural unit selected from the group consisting of structural units derived from a monomer having a cyclic ether structure other than an epoxy structure or an oxetane structure, and structural units derived from a monomer having an acyclic ether structure. Disclosure 14 is the pressure-sensitive adhesive tape of Disclosure 13, wherein the (meth)acrylic copolymer contains 0.01% by mass or more and 50% by mass or less of the structural units derived from a monomer having a cyclic ether structure other than an epoxy structure or an oxetane structure, and the structural units derived from a monomer having an acyclic ether structure. Disclosure 15 is the pressure-sensitive adhesive tape of Disclosures 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, wherein the (meth)acrylic copolymer contains structural units derived from a monomer having no crosslinkable functional group and having a glass transition temperature of 0° C. or higher when made into a homopolymer. Disclosure 16 is the pressure-sensitive adhesive tape of Disclosure 15, wherein the (meth)acrylic copolymer contains 0.1% by mass or more and 70% by mass or less of the monomer having no crosslinkable functional group and having a glass transition temperature of 0° C. or higher when made into a homopolymer. Disclosure 17 is the pressure-sensitive adhesive tape of Disclosures 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, wherein the (meth)acrylic copolymer has a weight-average molecular weight of 300,000 or more and 1,500,000 or less and a polydispersity index of 7.0 or less.

[0023] Disclosure 18 is the pressure-sensitive adhesive tape of Disclosures 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17, wherein the pressure-sensitive adhesive composition contains a tackifier, and the content of the tackifier in the pressure-sensitive adhesive composition is 10 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the (meth)acrylic copolymer. Disclosure 19 is the pressure-sensitive adhesive tape of Disclosure 18, wherein the tackifier comprises a tackifier having a softening point of 80°C or more and 170°C or less. Disclosure 20 is the pressure-sensitive adhesive tape of Disclosure 18 or 19, wherein the tackifier comprises a tackifier having a hydroxyl value of 20 mgKOH / g or more and 150 mgKOH / g or less. Disclosure 21 is the pressure-sensitive adhesive tape of Disclosures 18, 19, or 20, wherein the tackifier comprises at least one selected from the group consisting of a rosin ester tackifier, a terpene tackifier, and an acrylic tackifier.

[0023] Disclosure 22 is the pressure-sensitive adhesive tape of Disclosure 21, wherein the tackifier comprises the rosin ester-based tackifier and the terpene-based tackifier. Disclosure 23 is the pressure-sensitive adhesive tape of Disclosures 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22, wherein the pressure-sensitive adhesive composition contains a crosslinking agent, and the crosslinking agent comprises at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent. Disclosure 24 is the pressure-sensitive adhesive tape of Disclosure 23, wherein the crosslinking agent comprises the isocyanate-based crosslinking agent and the epoxy-based crosslinking agent. Disclosure 25 is the pressure-sensitive adhesive tape of Disclosure 23 or 24, wherein the content of the crosslinking agent in the pressure-sensitive adhesive composition relative to 100 parts by mass of the (meth)acrylic copolymer is 0.01 parts by mass or more and 10 parts by mass or less.

[0032] The present disclosure 26 is the pressure-sensitive 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, or 25, wherein the pressure-sensitive adhesive layer has a gel fraction of 20% by mass or more and 70% by mass or less.

[0033] The present disclosure 27 is the pressure-sensitive 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, or 26, wherein the pressure-sensitive adhesive layer has a thickness of 5 μm or more.Disclosure 28 is the pressure-sensitive 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, or 27, wherein the pressure-sensitive adhesive layer has a loss tangent peak height of 1.50 or less as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of −40° C. or more and 200° C. or less. Disclosure 29 is the pressure-sensitive 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, or 28, comprising a base layer and pressure-sensitive adhesive layers on both sides of the base layer, the pressure-sensitive adhesive layer being on at least one side of the base layer. Disclosure 30 is the pressure-sensitive 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, or 28, which does not have a substrate layer. The present invention will be described in detail below.

[0009] The present inventors have investigated adjusting the glass transition temperature and half-width of the peak of loss tangent measured by dynamic viscoelasticity measurement for a pressure-sensitive adhesive layer in a pressure-sensitive adhesive tape. As a result, they have found that a pressure-sensitive adhesive layer having excellent heat resistance and excellent impact absorption against various impacts can be obtained. They have also found that by using such a pressure-sensitive adhesive layer, a pressure-sensitive adhesive tape having excellent heat resistance and excellent impact resistance against various impacts can be obtained, thereby completing the present invention. The pressure-sensitive adhesive tape of the present invention is excellent in impact absorption against impacts received by an object over a wide range of speeds (e.g., dropping from various heights), and therefore in impact resistance. Furthermore, the pressure-sensitive adhesive tape of the present invention can have excellent impact resistance without increasing the thickness of the pressure-sensitive adhesive layer.

[0010] In this specification, the type of each structural unit in the (meth)acrylic copolymer described below and each component in the pressure-sensitive adhesive composition may be of only one type or of two or more types, unless otherwise specified. Furthermore, in this specification, unless otherwise specified, the terms "content ratio" and "content amount" refer to the total content ratio of all types of structural units or the total content amount of all types of components, when two or more types of structural units or components that define the "content ratio" are included.

[0011] The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition. The glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the height of the loss tangent peak of the pressure-sensitive adhesive layer, the shear storage modulus of the pressure-sensitive adhesive layer, the gel fraction of the pressure-sensitive adhesive layer, and the content of biological carbon of the pressure-sensitive adhesive layer can be adjusted to the values ​​described below by adjusting the type and content of each component constituting the pressure-sensitive adhesive composition. Examples of methods for forming a pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition include applying the pressure-sensitive adhesive composition to a release film or the like and then heating and drying the pressure-sensitive adhesive composition. The pressure-sensitive adhesive layer may contain either an uncrosslinked pressure-sensitive adhesive composition or a crosslinked product of the pressure-sensitive adhesive composition.

[0012] The pressure-sensitive adhesive layer has a glass transition temperature (hereinafter sometimes simply referred to as the "glass transition temperature of the pressure-sensitive adhesive layer") of 0°C, as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C. When the glass transition temperature of the pressure-sensitive adhesive layer is 0°C or higher, the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape is improved. Furthermore, the pressure-sensitive adhesive tape has excellent retention performance at high temperatures. The preferred lower limit of the glass transition temperature of the pressure-sensitive adhesive layer is 5°C, more preferably 10°C, and even more preferably 12°C. Furthermore, the preferred upper limit of the glass transition temperature of the pressure-sensitive adhesive layer is 30°C. When the glass transition temperature of the pressure-sensitive adhesive layer is 30°C or lower, the pressure-sensitive adhesive layer has appropriate tack at room temperature, and the resulting pressure-sensitive adhesive tape can further reduce adhesion defects during application. Furthermore, the pressure-sensitive adhesive layer has appropriate flexibility, which enables it to absorb even larger impacts, resulting in the resulting pressure-sensitive adhesive tape having excellent impact resistance. The upper limit of the glass transition temperature of the pressure-sensitive adhesive layer is more preferably 27° C., and even more preferably 25° C. Examples of the range of the glass transition temperature of the pressure-sensitive adhesive layer include ranges of 0° C. or higher and 30° C. or lower, 0° C. or higher and 27° C. or lower, 0° C. or higher and 25° C. or lower, 5° C. or higher and 30° C. or lower, 5° C. or higher and 27° C. or lower, 5° C. or higher and 25° C. or lower, 10° C. or higher and 30° C. or lower, 10° C. or higher and 27° C. or lower, 10° C. or higher and 25° C. or lower, 12° C. or higher and 30° C. or lower, 12° C. or higher and 27° C. or lower, and 12° C. or higher and 25° C. or lower. In this specification, the "glass transition temperature of the pressure-sensitive adhesive layer" refers to the temperature at which a maximum due to micro-Brownian motion appears among the maximums of loss tangent (tan δ) obtained by dynamic viscoelasticity measurement. Furthermore, when there are multiple maxima of the loss tangent, in this specification, the "glass transition temperature of the pressure-sensitive adhesive layer" means the temperature at which the lowest maximum of the loss tangent appears among the maxima of the loss tangent in the range of -25°C to 50°C.

[0013] Specific methods for adjusting the glass transition temperature of the pressure-sensitive adhesive layer include, for example, a method of using a branched alkyl (meth)acrylate as a constituent monomer of the (meth)acrylic copolymer and adjusting its content ratio, a method of adjusting the content of a tackifier, a method of using a tackifier having a softening point within a specific range as a tackifier, and a method of adjusting the content of a crosslinking agent or the content of a monomer having a crosslinkable functional group, thereby adjusting the gel fraction of the pressure-sensitive adhesive layer.

[0014] The pressure-sensitive adhesive layer has a loss tangent (hereinafter sometimes simply referred to as "loss tangent of the pressure-sensitive adhesive layer") measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C, with a lower limit of 38°C. Typically, when the loss tangent of the pressure-sensitive adhesive layer increases at a specific temperature, the impact absorption of the pressure-sensitive adhesive layer at that temperature improves. Therefore, when the half-width of the peak of the loss tangent of the pressure-sensitive adhesive layer increases, the temperature range over which the loss tangent of the pressure-sensitive adhesive layer is high broadens, and therefore the temperature range over which the pressure-sensitive adhesive layer has excellent impact absorption broadens. Meanwhile, according to the temperature-velocity conversion law, the loss tangent of the pressure-sensitive adhesive layer at a certain temperature can be converted into impact absorption against an impact received by an object behaving at a certain speed. Therefore, when the temperature range over which the loss tangent of the pressure-sensitive adhesive layer is high broadens, the pressure-sensitive adhesive layer has excellent impact absorption against impacts received by an object over a wide speed range (e.g., dropping from various heights). When the half-value width of the peak of the loss tangent of the pressure-sensitive adhesive layer is 38°C or more, the pressure-sensitive adhesive layer has improved impact absorption properties over a wide speed range, and the resulting pressure-sensitive adhesive tape has excellent impact resistance against various impacts. The lower limit of the half-value width of the peak of the loss tangent of the pressure-sensitive adhesive layer is preferably 40°C, more preferably 42°C, and even more preferably 44°C. The upper limit of the half-value width of the peak of the loss tangent of the pressure-sensitive adhesive layer is preferably 50°C. When the half-value width of the loss tangent of the pressure-sensitive adhesive layer is 50°C or less, the pressure-sensitive adhesive layer can be prevented from excessively dispersing stress applied to the pressure-sensitive adhesive layer, and the resulting pressure-sensitive adhesive tape has excellent reworkability. The upper limit of the half-value width of the loss tangent of the pressure-sensitive adhesive layer is more preferably 48°C, and even more preferably 46°C. Examples of the range of the half width of the loss tangent peak of the pressure-sensitive adhesive layer include ranges of 38°C or higher and 50°C or lower, 38°C or higher and 48°C or lower, 38°C or higher and 46°C or lower, 40°C or higher and 50°C or lower, 40°C or higher and 48°C or lower, 40°C or higher and 46°C or lower, 42°C or higher and 50°C or lower, 42°C or higher and 48°C or lower, 42°C or higher and 46°C or lower, 44°C or higher and 50°C or lower, 44°C or higher and 48°C or lower, and 44°C or higher and 46°C or lower.In addition, when there are multiple peaks of the loss tangent of the pressure-sensitive adhesive layer, in this specification, the above-mentioned "half width of the peak of the pressure-sensitive adhesive layer" means the half width of the peak at the lowest temperature among the peaks of the loss tangent of the pressure-sensitive adhesive layer in the temperature range of -25°C to 50°C. Furthermore, in this specification, the "half width" means the full width at half maximum.

[0015] Specific methods for adjusting the half width of the loss tangent peak of the pressure-sensitive adhesive layer include, for example, a method of adjusting the peak height of the loss tangent of the pressure-sensitive adhesive layer, which will be described later, and a method of adjusting the content ratio of a branched alkyl(meth)acrylate, an alkyl(meth)acrylate having an alkyl group having from 7 to 10 carbon atoms, an alkyl(meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer, or an alkyl(meth)acrylate having a boiling point of 200° C. or higher, as a constituent monomer of the (meth)acrylic copolymer.

[0016] The pressure-sensitive adhesive layer preferably has an upper limit of 1.50 for the peak height of the loss tangent measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C. When the peak height of the loss tangent of the pressure-sensitive adhesive layer is 1.50 or less, the half-width of the loss tangent of the pressure-sensitive adhesive layer increases, and the pressure-sensitive adhesive layer therefore has improved impact absorption properties over a wide speed range. As a result, the pressure-sensitive adhesive tape obtained has excellent impact resistance against various impacts. The upper limit of the peak height of the loss tangent of the pressure-sensitive adhesive layer is more preferably 1.40, even more preferably 1.35, and even more preferably 1.32. The lower limit of the peak height of the loss tangent of the pressure-sensitive adhesive layer is preferably 1.20. When the peak height of the loss tangent of the pressure-sensitive adhesive layer is 1.20 or more, the half-width of the loss tangent of the pressure-sensitive adhesive layer does not become too large, and the pressure-sensitive adhesive layer can be prevented from excessively dispersing stress applied to the pressure-sensitive adhesive layer, thereby resulting in the pressure-sensitive adhesive tape obtained having excellent reworkability. A more preferred lower limit of the peak height of the loss tangent of the pressure-sensitive adhesive layer is 1.25. Examples of ranges for the peak height of the loss tangent of the pressure-sensitive adhesive layer include 1.20 or more and 1.50 or less, 1.20 or more and 1.40 or less, 1.20 or more and 1.35 or less, 1.20 or more and 1.32 or less, 1.25 or more and 1.50 or less, 1.25 or more and 1.40 or less, 1.25 or more and 1.35 or less, and 1.25 or more and 1.32 or less. When the pressure-sensitive adhesive layer has multiple loss tangent peaks, in this specification, the "peak height of the pressure-sensitive adhesive layer" refers to the height of the peak at the lowest temperature among the loss tangent peaks of the pressure-sensitive adhesive layer in the temperature range of -25°C to 50°C.

[0017] The pressure-sensitive adhesive layer has a shear storage modulus at 80°C (hereinafter, sometimes simply referred to as "the shear storage modulus of the pressure-sensitive adhesive layer at 80°C") measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C) of 2.0 x 10 ４ The pressure-sensitive adhesive layer has a shear storage modulus of 2.0×10 Pa at 80° C. ４When the shear storage modulus at 80°C is 2.5 x 10 Pa or more, the pressure-sensitive adhesive layer has an appropriate tack at room temperature, and the obtained pressure-sensitive adhesive tape has excellent adhesion at room temperature. ４ Pa, and a more preferable lower limit is 3.0 × 10 ４ Pa, and an even more preferable lower limit is 3.5 × 10 ４ The preferred upper limit of the shear storage modulus of the pressure-sensitive adhesive layer at 80°C is 7.0 × 10 ４ The pressure-sensitive adhesive layer has a shear storage modulus of 7.0×10 Pa at 80° C. ４ By setting the shear storage modulus at 80°C to 6.5 x 10 Pa or less, the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape is further improved. In addition, since the softening of the pressure-sensitive adhesive layer at high temperatures can be further suppressed, the resulting pressure-sensitive adhesive tape has better holding performance at high temperatures. A more preferable upper limit of the shear storage modulus at 80°C of the pressure-sensitive adhesive layer is 6.5 x 10 ４ Pa, and a more preferable upper limit is 6.0 × 10 ４ The range of the shear storage modulus of the pressure-sensitive adhesive layer at 80°C is, for example, 2.0 × 10 ４ Pa or more 7.0×10 ４ Below, 2.0 x 10 ４ Pa or more 6.5×10 ４ Below, 2.0 x 10 ４ Pa or more 6.0×10 ４ Below, 2.5 x 10 ４ Pa or more 7.0×10 ４ Below, 2.5 x 10 ４ Pa or more 6.5×10 ４ Below, 2.5 x 10 ４ Pa or more 6.0×10 ４ Below, 3.0 x 10 ４ Pa or more 7.0×10 ４ Below, 3.0 x 10 ４ Pa or more 6.5×10 ４ Below, 3.0 x 10 ４ Pa or more 6.0×10 ４ Below, 3.5 x 10 ４ Pa or more 7.0×10 ４ Below, 3.5 x 10 ４ Pa or more 6.5×10４ Below, 3.5 x 10 ４ Pa or more 6.0×10 ４ The range includes the following:

[0018] The pressure-sensitive adhesive layer has a shear storage modulus at −15° C. measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of −40° C. to 200° C. (hereinafter, may be simply referred to as “shear storage modulus at −15° C. of the pressure-sensitive adhesive layer”) of preferably 30×10 ６ The pressure-sensitive adhesive layer has a shear storage modulus of 30×10 at −15° C. ６ By having a shear storage modulus of at least 40×10 Pa, the pressure-sensitive adhesive layer has a moderate tack even in a low-temperature environment, and the resulting pressure-sensitive adhesive tape has excellent adhesion even in a low-temperature environment. ６ Pa, and a more preferable lower limit is 50×10 ６ The preferred upper limit of the shear storage modulus of the pressure-sensitive adhesive layer at −15° C. is 250×10 ６ Pa, and a more preferable upper limit is 200×10 ６ Pa, and a more preferable upper limit is 150×10 ６ The range of the shear storage modulus of the pressure-sensitive adhesive layer at −15° C. is 30×10 ６ Pa or more 250Pa×10 ６ Below, 40 x 10 ６ Pa or more 200×10 ６ Pa (practical upper limit) or less, 50 x 10 ６ Pa or more 150×10 ６ Pa or less.

[0019] The glass transition temperature of the pressure-sensitive adhesive layer, the peak and half-width of the loss tangent of the pressure-sensitive adhesive layer, and the shear storage modulus of the pressure-sensitive adhesive layer at 80°C and -15°C are measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz. Specifically, the pressure-sensitive adhesive layers are first stacked to prepare a laminate approximately 1 mm thick, which is then cut into a width of 6 mm and a length of 10 mm to obtain a test specimen. Next, the obtained test specimen is subjected to dynamic viscoelasticity measurement using a dynamic viscoelasticity measurement device in shear mode under a nitrogen atmosphere at a measurement temperature range of -40°C to 200°C, a heating rate of 5°C / min, a frequency of 1 Hz, and a strain of 0.08%. Examples of the dynamic viscoelasticity measurement device include the DVA-200 (manufactured by IT Measurement & Control Co., Ltd.). Furthermore, the half-width of the loss tangent of the pressure-sensitive adhesive layer and the peak height of the loss tangent of the pressure-sensitive adhesive layer can be obtained from the dynamic viscoelasticity spectrum obtained by dynamic viscoelasticity measurement.

[0020] The pressure-sensitive adhesive layer preferably has a lower limit of 0.50 in shear storage modulus at 65°C. When the pressure-sensitive adhesive layer has a loss tangent at 65°C of 0.50 or more, the resulting pressure-sensitive adhesive tape has excellent stress relaxation properties and can be more suitably used for fixing an adherend having a curved portion. The pressure-sensitive adhesive layer's loss tangent at 65°C is more preferably 0.52, and even more preferably 0.54. The pressure-sensitive adhesive layer's loss tangent at 65°C is preferably 0.70. When the pressure-sensitive adhesive layer has a loss tangent at 65°C of 0.70 or less, the resulting pressure-sensitive adhesive tape can be more suitably used for fixing an adherend having a curved portion, even in a high-temperature environment, without losing its adhesive strength. The pressure-sensitive adhesive layer's loss tangent at 65°C is more preferably 0.65, and even more preferably 0.60. Examples of the loss tangent range of the pressure-sensitive adhesive layer at 65°C include 0.50 or more and 0.70 or less, 0.50 or more and 0.65 or less, 0.50 or more and 0.60 or less, 0.52 or more and 0.70 or less, 0.52 or more and 0.65 or less, 0.52 or more and 0.60 or less, 0.54 or more and 0.70 or less, 0.54 or more and 0.65 or less, and 0.54 or more and 0.60 or less.

[0021] The pressure-sensitive adhesive layer preferably has a lower limit of shear storage modulus at 23°C of 0.25 MPa. When the pressure-sensitive adhesive layer has a shear storage modulus at 23°C of 0.25 MPa or more, tackiness of the pressure-sensitive adhesive layer can be further suppressed, resulting in superior initial reworkability of the resulting pressure-sensitive adhesive tape. The pressure-sensitive adhesive layer more preferably has a lower limit of shear storage modulus at 23°C of 0.35 MPa, and even more preferably has a lower limit of 0.45 MPa. The pressure-sensitive adhesive layer preferably has an upper limit of shear storage modulus at 23°C of 1.0 MPa. When the pressure-sensitive adhesive layer has a shear storage modulus at 23°C of 1.0 MPa or less, the pressure-sensitive adhesive layer does not become too hard, thereby further improving the adhesive strength of the resulting pressure-sensitive adhesive tape and making it more suitable for use in fixing an adherend having a curved portion. The pressure-sensitive adhesive layer more preferably has an upper limit of shear storage modulus at 23°C of 0.80 MPa, and even more preferably has an upper limit of 0.70 MPa. The shear storage modulus of the pressure-sensitive adhesive layer at 23°C may be, for example, in the range of 0.25 MPa or more and 1.0 MPa or less, 0.25 MPa or more and 0.80 MPa or less, 0.25 MPa or more and 0.70 MPa or less, 0.35 MPa or more and 1.0 MPa or less, 0.35 MPa or more and 0.80 MPa or less, 0.35 MPa or more and 0.70 MPa or less, 0.45 MPa or more and 1.0 MPa or less, 0.45 MPa or more and 0.80 MPa or less, or 0.45 MPa or more and 0.70 MPa or less.

[0022] The pressure-sensitive adhesive layer preferably has a shear storage modulus of 0.25 MPa or more at 23° C. and a loss tangent of 0.50 or more at 65° C. When the pressure-sensitive adhesive layer has a shear storage modulus of 0.25 MPa or more at 23° C. and a loss tangent of 0.50 or more at 65° C., the resulting pressure-sensitive adhesive tape has better initial reworkability and can be more suitably used for fixing an adherend having a bent portion.

[0023] The shear storage modulus of the pressure-sensitive adhesive layer at 23°C and the loss tangent of the pressure-sensitive adhesive layer at 65°C are measured by dynamic viscoelasticity measurement at a frequency of 1 Hz. Specifically, first, the pressure-sensitive adhesive layers alone are stacked to prepare a laminate approximately 1 mm thick, which is then cut into a width of 6 mm and a length of 10 mm to obtain a test piece. Next, the obtained test piece is subjected to dynamic viscoelasticity measurement using a dynamic viscoelasticity measurement device in shear mode under a nitrogen atmosphere at a measurement temperature of -50°C to 150°C, a heating rate of 5°C / min, a frequency of 1 Hz, and a strain of 0.1%. Examples of the dynamic viscoelasticity measurement device include the DVA-200 (manufactured by IT Measurement & Control Co., Ltd.).

[0024] Specific methods for adjusting the shear storage modulus at 23°C of the pressure-sensitive adhesive layer include, for example, a method of adjusting the type or content of a tackifier, and a method of adjusting the type or content ratio of a monomer contained in the (meth)acrylic copolymer.

[0025] Specific methods for adjusting the loss tangent at 65°C of the pressure-sensitive adhesive layer include, for example, a method for adjusting the weight average molecular weight of the (meth)acrylic copolymer, a method for adjusting the type or content ratio of a monomer having a crosslinkable functional group, a method for adjusting the type or content of a crosslinking agent, and the like.

[0026] The pressure-sensitive adhesive composition contains a (meth)acrylic copolymer. The (meth)acrylic copolymer preferably has a structural unit derived from an alkyl(meth)acrylate. In this specification, the term "(meth)acrylic" refers to acrylic or methacrylic, and the term "(meth)acrylate" refers to acrylate or methacrylate.

[0027] From the viewpoint of making it easier to design a wide half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the alkyl (meth)acrylate in the structural unit derived from the alkyl (meth)acrylate preferably includes a (meth)acrylate having an alkyl group having 7 to 10 carbon atoms (hereinafter sometimes referred to as "alkyl (meth)acrylate (a)").

[0028] Examples of the alkyl (meth)acrylate (a) include n-heptyl (meth)acrylate, 1-methylhexyl (meth)acrylate, n-octyl (meth)acrylate, 1-methylheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, 1-methyloctyl (meth)acrylate, etc. Among these, n-heptyl (meth)acrylate and 1-methylheptyl (meth)acrylate are preferred from the viewpoint of achieving both heat resistance and impact resistance against various impacts.

[0029] The preferred lower limit of the content of the structural units derived from the alkyl (meth)acrylate (a) in the (meth)acrylic copolymer is 45% by mass. When the content of the structural units derived from the alkyl (meth)acrylate (a) is 45% by mass or more, the half-value width of the loss tangent of the pressure-sensitive adhesive layer can be easily adjusted within the above-mentioned range, thereby providing the resulting pressure-sensitive adhesive tape with superior impact resistance against various impacts. A more preferred lower limit of the content of the structural units derived from the alkyl (meth)acrylate (a) is 60% by mass, an even more preferred lower limit is 70% by mass, and an even more preferred lower limit is 80% by mass. Furthermore, a preferred upper limit of the content of the structural units derived from the alkyl (meth)acrylate (a) is 98% by mass. When the content of the structural units derived from the alkyl (meth)acrylate (a) is 98% by mass or less, the (meth)acrylic copolymer can contain structural units derived from the monomer having the crosslinkable functional group. This makes it easier for the pressure-sensitive adhesive layer to form a crosslinked structure, thereby providing appropriate bulk strength. The content of the structural units derived from the alkyl (meth)acrylate (a) is more preferably 95% by mass, and even more preferably 90% by mass. The range of the content of the structural units derived from the alkyl (meth)acrylate (a) can be, for example, 45% by mass or more and 98% by mass or less, 45% by mass or more and 95% by mass or less, 45% by mass or more and 90% by mass or less, 60% by mass or more and 98% by mass or less, 60% by mass or more and 95% by mass or less, 60% by mass or more and 90% by mass or less, 70% by mass or more and 98% by mass or less, 70% by mass or more and 95% by mass or less, 70% by mass or more and 90% by mass or less, 80% by mass or more and 98% by mass or less, 80% by mass or more and 95% by mass or less, 80% by mass or more and 90% by mass or less. The content of the structural units derived from the alkyl (meth)acrylate (a) can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy ( １ H-NMR, １３ The carbon number can be calculated from the integrated intensity ratio of the peak of hydrogen derived from the alkyl (meth)acrylate (a) by performing spectroscopy (C-NMR, etc.).

[0030] The alkyl(meth)acrylate in the structural unit derived from the alkyl(meth)acrylate preferably includes an alkyl(meth)acrylate having a branched alkyl group (hereinafter sometimes referred to as "alkyl(meth)acrylate (b)"), from the viewpoint of increasing the glass transition temperature of the pressure-sensitive adhesive layer and making it easier to design a wide half-value width of the loss tangent peak of the pressure-sensitive adhesive layer.

[0031] Examples of the alkyl (meth)acrylate (b) include isobutyl (meth)acrylate, isoamyl acrylate, 1-methylheptyl acrylate, 1-methylheptyl methacrylate, isodecyl methacrylate, isostearyl acrylate, etc. Of these, 1-methylheptyl (meth)acrylate, etc. is preferred.

[0032] The preferred lower limit of the content of the structural units derived from the alkyl (meth)acrylate (b) in the (meth)acrylic copolymer is 45% by mass. When the content of the structural units derived from the alkyl (meth)acrylate (b) is 45% by mass or more, the glass transition temperature of the pressure-sensitive adhesive layer and the half-width of the loss tangent of the pressure-sensitive adhesive layer can be easily adjusted within the above-mentioned ranges, and the resulting pressure-sensitive adhesive tape has excellent heat resistance and is more excellent in impact resistance against various impacts. A more preferred lower limit of the content of the structural units derived from the alkyl (meth)acrylate (b) is 60% by mass, an even more preferred lower limit is 70% by mass, and an even more preferred lower limit is 80% by mass. The preferred upper limit of the content of the structural units derived from the alkyl (meth)acrylate (b) is 98% by mass. By setting the content of the structural unit derived from the alkyl (meth)acrylate (b) to 98% by mass or less, the (meth)acrylic copolymer can have a structural unit derived from the monomer having the crosslinkable functional group, which makes it easier for the pressure-sensitive adhesive layer to form a crosslinked structure and therefore tends to have appropriate bulk strength. A more preferred upper limit of the content of the structural unit derived from the alkyl (meth)acrylate (b) is 95% by mass, and an even more preferred upper limit is 92% by mass. The range of the content of the structural unit derived from the alkyl (meth)acrylate (b) may be, for example, 45% by mass or more and 98% by mass or less, 45% by mass or more and 95% by mass or less, 45% by mass or more and 90% by mass or less, 60% by mass or more and 98% by mass or less, 60% by mass or more and 95% by mass or less, 60% by mass or more and 90% by mass or less, 70% by mass or more and 98% by mass or less, 70% by mass or more and 95% by mass or less, 70% by mass or more and 90% by mass or less, 80% by mass or more and 98% by mass or less, 80% by mass or more and 95% by mass or less, 80% by mass or more and 90% by mass or less, etc. The content of the structural unit derived from the alkyl (meth)acrylate (b) may be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy ( １ H-NMR, １３ The carbon number can be calculated from the integrated intensity ratio of the hydrogen peak derived from the alkyl (meth)acrylate (b) by performing spectroscopy (C-NMR, etc.).

[0033] The alkyl(meth)acrylate preferably includes an alkyl(meth)acrylate having a branched alkyl group having 7 to 10 carbon atoms as the alkyl(meth)acrylate (a) and the alkyl(meth)acrylate (b), and more preferably includes 1-methylheptyl(meth)acrylate.

[0034] The alkyl (meth)acrylate preferably contains an alkyl (meth)acrylate having a boiling point of 200°C or higher. By containing an alkyl (meth)acrylate having a boiling point of 200°C or higher, the half width of the loss tangent of the pressure-sensitive adhesive layer can be easily adjusted within the above-mentioned range, and the resulting pressure-sensitive adhesive tape has better impact resistance against various impacts. The lower limit of the boiling point of the alkyl (meth)acrylate having a boiling point of 200°C or higher is more preferably 210°C, and even more preferably 215°C. Furthermore, the upper limit of the boiling point of the alkyl (meth)acrylate having a boiling point of 200°C or higher is preferably 250°C, and more preferably 230°C, from the viewpoint of making it easier to adjust the weight-average molecular weight to the desired value when copolymerizing the (meth)acrylic copolymer. Examples of the boiling point range of the alkyl (meth)acrylate having a boiling point of 200° C. or higher include 200° C. or higher and 250° C. or lower, 200° C. or higher and 230° C. or lower, 210° C. or higher and 250° C. or lower, 210° C. or higher and 230° C. or lower, 215° C. or higher and 250° C. or lower, and 215° C. or higher and 230° C. or lower. In this specification, the "boiling point of the alkyl (meth)acrylate" means the boiling point at 101 kPa.

[0035] Examples of the alkyl(meth)acrylate having a boiling point of 200°C or higher include n-heptyl acrylate (boiling point: 222°C), n-heptyl methacrylate (boiling point: 229°C), 1-methylheptyl acrylate (boiling point: 218°C), 2-ethylhexyl acrylate (boiling point: 215°C), 2-ethylhexyl methacrylate (boiling point: 214°C), etc. Of these, 1-methylheptyl acrylate, 1-methylheptyl methacrylate, n-heptyl acrylate, and n-heptyl methacrylate are preferred, and 1-methylheptyl acrylate and 1-methylheptyl methacrylate are more preferred.

[0036] The alkyl (meth)acrylate preferably contains an alkyl (meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer. By containing an alkyl (meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer, the half-width of the loss tangent of the pressure-sensitive adhesive layer can be more easily adjusted to within the above-mentioned range, and the resulting pressure-sensitive adhesive tape has better impact resistance against various impacts. The lower limit of the glass transition temperature of the alkyl (meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer is more preferably −48° C., and even more preferably −46° C. Furthermore, the upper limit of the glass transition temperature of the alkyl (meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer is preferably 0° C., and more preferably −20° C., from the viewpoint of making it easier to adjust the half-width of the peak of the loss tangent of the pressure-sensitive adhesive layer to within the above-mentioned range. Examples of the range of the glass transition temperature of the alkyl (meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer include ranges of −50° C. or higher and 0° C. or lower, −50° C. or higher and −20° C. or lower, −48° C. or higher and 0° C. or lower, −48° C. or higher and −20° C. or lower, −46° C. or higher and 0° C. or lower, and −46° C. or higher and −20° C. or lower. In this specification, the term “glass transition temperature when made into a homopolymer” refers to the glass transition temperature measured by differential scanning calorimetry of a homopolymer in which the alkyl (meth)acrylate has a weight average molecular weight of 100,000 or higher and 2,000,000 or lower. The glass transition temperature of the homopolymer can be measured, for example, 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.

[0037] Examples of the alkyl(meth)acrylate having a glass transition temperature of −50° C. or higher when made into a homopolymer include 1-methylheptyl acrylate (glass transition temperature when made into a homopolymer: −45° C.).

[0038] The alkyl (meth)acrylate may include alkyl (meth)acrylates other than the alkyl (meth)acrylate (a), the alkyl (meth)acrylate (b), the alkyl (meth)acrylate having a boiling point of 200°C or higher, and the alkyl (meth)acrylate having a glass transition temperature of -50°C or higher when formed into a homopolymer.

[0039] The alkyl (meth)acrylate may be composed solely of petroleum-derived materials, but preferably contains a biologically-derived material. In recent years, the depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products have become a problem. Therefore, attempts have been made to conserve petroleum resources by using biologically-derived materials instead of petroleum-derived materials. The inclusion of a biologically-derived material in the alkyl (meth)acrylate is preferable from the viewpoint of conserving petroleum resources. Furthermore, since biologically-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, their combustion is thought to not increase the total amount of carbon dioxide in the atmosphere, and is therefore also preferable from the viewpoint of reducing carbon dioxide emissions.

[0040] When the alkyl(meth)acrylate in the alkyl(meth)acrylate-derived structural unit contains a biological material, the alkyl(meth)acrylate is preferably synthesized by esterifying a biological alcohol with (meth)acrylic acid. Examples of methods for obtaining the biological alcohol include a method in which a material collected from plants or animals (e.g., ricinoleic acid derived from castor oil) is used as a raw material, and an alkali-fused mixture is distilled to obtain 1-methylheptyl alcohol, a biological material, at low cost and easily.

[0041] The (meth)acrylic copolymer preferably has a structural unit derived from a monomer having a crosslinkable functional group. When the (meth)acrylic copolymer has a structural unit derived from a monomer having a crosslinkable functional group, the pressure-sensitive adhesive layer more easily forms a crosslinked structure.

[0042] Examples of the monomer having a crosslinkable functional group include a carboxy group-containing monomer, a hydroxy group-containing monomer, a glycidyl group-containing monomer, an amide group-containing monomer, and a nitrile group-containing monomer. Among these, the monomer having a crosslinkable functional group preferably includes at least one selected from the group consisting of a carboxy group-containing monomer and a hydroxy group-containing monomer, since this facilitates adjustment of the degree of crosslinking of the pressure-sensitive adhesive composition. The homopolymer Tg of the monomer having a crosslinkable functional group is not particularly limited and may be 0°C or higher. The monomer having a crosslinkable functional group preferably has a (meth)acryloyl group. In this specification, the term "(meth)acryloyl" refers to acryloyl or methacryloyl.

[0043] Examples of the carboxy group-containing monomer include unsaturated monocarboxylic acids such as (meth)acrylic acid, (meth)acryloylacetic acid, (meth)acryloylpropionic acid, (meth)acryloylbutyric acid, (meth)acryloylpentanoic acid, and crotonic acid, and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, citraconic acid, mesaconic acid, and itaconic acid. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 1-methyl-2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1-methyl-2-hydroxypropyl (meth)acrylate, 1-methyl-3-hydroxypropyl (meth)acrylate, 1-ethyl-2-hydroxyethyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 9-hydroxynonyl (meth)acrylate, polypropylene glycol mono(meth)acrylate, etc. Examples of the glycidyl group-containing monomer include glycidyl (meth)acrylate, etc. Examples of the amide group-containing monomer include dimethyl(meth)acrylamide, isopropyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, etc. Examples of the nitrile group-containing monomer include (meth)acrylonitrile, etc.

[0044] The preferred lower limit of the content of the structural unit derived from the monomer having a crosslinkable functional group in the (meth)acrylic copolymer is 0.01% by mass, and the preferred upper limit is 20% by mass. When the content of the structural unit derived from the monomer having a crosslinkable functional group is 0.01% by mass or more, the pressure-sensitive adhesive layer is more likely to form a crosslinked structure, resulting in appropriate bulk strength, and thus the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape is further improved. Furthermore, the pressure-sensitive adhesive tape has improved retention performance at high temperatures. When the content of the structural unit derived from the monomer having a crosslinkable functional group is 20% by mass or less, the pressure-sensitive adhesive layer has appropriate flexibility, enabling it to absorb even larger impacts, resulting in the resulting pressure-sensitive adhesive tape having superior impact resistance. The more preferred lower limit of the content of the structural unit derived from the monomer having a crosslinkable functional group is 0.1% by mass, and the more preferred upper limit is 10% by mass, even more preferred lower limit is 0.2% by mass, even more preferred upper limit is 7.0% by mass, and even more preferred lower limit is 1.0% by mass. The range of the content of the structural unit derived from the monomer having a crosslinkable functional group can be, for example, 0.01% by mass to 20% by mass, 0.01% by mass to 10% by mass, 0.01% by mass to 7.0% by mass, 0.1% by mass to 20% by mass, 0.1% by mass to 10% by mass, 0.1% by mass to 7.0% by mass, 0.2% by mass to 20% by mass, 0.2% by mass to 10% by mass, 0.2% by mass to 7.0% by mass, 1.0% by mass to 20% by mass, 1.0% by mass to 10% by mass, and 1.0% by mass to 7.0% by mass. The content of the structural unit derived from the monomer having a crosslinkable functional group in the (meth)acrylic copolymer can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy ( １ H-NMR, １３ The crosslinking functional group content can be calculated from the integrated intensity ratio of the hydrogen peak derived from the monomer having the crosslinkable functional group by performing spectroscopy (e.g., C-NMR) on the polymer.

[0045] The preferred lower limit of the content of the structural units derived from the hydroxyl group-containing monomer in the (meth)acrylic copolymer is 0.01% by mass, and the preferred upper limit is 2.0% by mass. When the content of the structural units derived from the hydroxyl group-containing monomer is within the above range, the pressure-sensitive adhesive layer is more likely to form a crosslinked structure and has appropriate bulk strength, thereby further improving the shear storage modulus at 80°C of the pressure-sensitive adhesive layer, and therefore further improving the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape. In addition, the pressure-sensitive adhesive tape has further improved retention performance at high temperatures. The more preferred lower limit of the content of the structural units derived from the hydroxyl group-containing monomer is 0.05% by mass, the more preferred upper limit is 1.0% by mass, and the even more preferred lower limit is 0.1% by mass. The content of the structural units derived from the hydroxyl group-containing monomer in the (meth)acrylic copolymer can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy ( １ H-NMR, １３ The amount of hydrogen can be calculated from the integrated intensity ratio of the hydrogen peak derived from the hydroxyl group-containing monomer by performing spectroscopy (e.g., C-NMR) on the hydroxyl group-containing monomer.

[0046] The preferred lower limit of the content of the structural unit derived from the carboxyl group-containing monomer in the (meth)acrylic copolymer is 0.1% by mass, and the preferred upper limit is 15% by mass. When the content of the structural unit derived from the carboxyl group-containing monomer is within the above range, the pressure-sensitive adhesive layer is more likely to form a crosslinked structure and has appropriate bulk strength, thereby further improving the shear storage modulus at 80°C of the pressure-sensitive adhesive layer, thereby further improving the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape. Furthermore, the pressure-sensitive adhesive tape has further improved retention performance at high temperatures. The more preferred lower limit of the content of the structural unit derived from the carboxyl group-containing monomer is 1.0% by mass, and the more preferred upper limit is 10% by mass, and even more preferred lower limit is 3.0% by mass, and even more preferred upper limit is 8.0% by mass. The range of the content of the structural unit derived from the carboxy group-containing monomer may be, for example, 0.1% by mass or more and 15% by mass or less, 0.1% by mass or more and 10% by mass or less, 0.1% by mass or more and 8.0% by mass or less, 1.0% by mass or more and 15% by mass or less, 1.0% by mass or more and 10% by mass or less, 1.0% by mass or more and 8.0% by mass or less, 3.0% by mass or more and 15% by mass or less, 3.0% by mass or more and 10% by mass or less, 3.0% by mass or more and 8.0% by mass or less. The content of the structural unit derived from the carboxy group-containing monomer in the (meth)acrylic copolymer can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy ( １ H-NMR, １３ The carbon number can be calculated from the integrated intensity ratio of the hydrogen peak derived from the carboxy group-containing monomer by performing spectroscopy (e.g., C-NMR) on the carbonyl group.

[0047] The (meth)acrylic copolymer preferably has at least one structural unit selected from the group consisting of structural units derived from monomers having a cyclic ether structure other than an epoxy structure or an oxetane structure, and structural units derived from monomers having an acyclic ether structure (hereinafter, sometimes simply referred to as "structural units derived from monomers having an ether structure"). When the (meth)acrylic copolymer has structural units derived from monomers having an ether structure, the glass transition temperature tends to be high, and it is easy to design a copolymer with excellent reworkability.

[0048] Examples of the monomer having a cyclic ether structure other than the epoxy structure and the oxetane structure include a monomer having a cyclic ether structure such as tetrahydrofurfuryl (meth)acrylate, etc. Examples of the monomer having an acyclic ether structure include a monomer having an acyclic ether structure such as 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, and ethyl carbitol (meth)acrylate.

[0049] The content of the structural units derived from the monomer having an ether structure in the (meth)acrylic copolymer is preferably 0.01% by mass at the lower limit and 50% by mass at the upper limit. When the content of the structural units derived from the monomer having an ether structure is 0.01% by mass or more, the glass transition temperature is likely to be high, and it is easy to design a structure with excellent reworkability. When the content of the structural units derived from the monomer having an ether structure is 50% by mass or less, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer is likely to be wide in the dynamic viscoelasticity spectrum, and it is easy to design a structure with excellent impact resistance against various impacts. The content of the structural units derived from the monomer having an ether structure is more preferably 0.1% by mass at the lower limit and more preferably 30% by mass at the upper limit, even more preferably 1% by mass at the lower limit and even more preferably 20% by mass at the upper limit. The range of the content of the structural units derived from the monomer having an ether structure can be, for example, 0.01% by mass or more and 50% by mass or less, 0.01% by mass or more and 30% by mass or less, 0.01% by mass or more and 20% by mass or less, 0.1% by mass or more and 50% by mass or less, 0.1% by mass or more and 30% by mass or less, 0.1% by mass or more and 20% by mass or less, 1% by mass or more and 50% by mass or less, 1% by mass or more and 30% by mass or less, 1% by mass or more and 20% by mass or less. The content of the structural units derived from the monomer having an ether structure can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy ( １ H-NMR, １３ C-NMR, etc.) and calculation can be performed from the integrated intensity ratio of the hydrogen peak derived from the structural unit derived from the monomer having the ether structure.

[0050] The (meth)acrylic copolymer may contain a constituent unit derived from a monomer other than the constituent unit derived from the alkyl (meth)acrylate, the constituent unit derived from the monomer having a crosslinkable functional group, and the constituent unit derived from the monomer having an ether structure, within the scope of not impairing the object of the present invention.

[0051] Examples of the other monomers include benzyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, etc. Furthermore, examples of the other monomers that can be used include various monomers that are commonly used as raw materials for (meth)acrylic copolymers, such as vinyl acetate and styrene.

[0052] The (meth)acrylic copolymer preferably has a structural unit derived from a monomer that does not have a crosslinkable functional group and has a glass transition temperature of 0°C or higher when made into a homopolymer. The (meth)acrylic copolymer has a structural unit derived from a monomer that does not have a crosslinkable functional group and has a homopolymer Tg of 0°C or higher, thereby enabling the copolymer to exhibit higher shear adhesive strength. The monomer that does not have a crosslinkable functional group and has a glass transition temperature of 0°C or higher when made into a homopolymer may be one of the other alkyl (meth)acrylates or a monomer other than the alkyl (meth)acrylates. The monomer that has a glass transition temperature of 0°C or higher when made into a homopolymer may be one of the monomers having an acyclic ether structure or a cyclic ether structure other than an epoxy structure or an oxetane structure.

[0053] Examples of the crosslinkable functional group in the monomer having no crosslinkable functional group and a homopolymer Tg of 0° C. or higher include a carboxy group, a hydroxyl group, a glycidyl group, an amide group, and a nitrile group.

[0054] Specific examples of the monomer having no crosslinkable functional group and a homopolymer Tg of 0°C or higher include n-hexyl methacrylate (homopolymer Tg: 0°C), t-butyl acrylate (homopolymer Tg: 14°C), t-butyl methacrylate (homopolymer Tg: 107°C), cyclohexyl acrylate (homopolymer Tg: 15°C), isobornyl acrylate (homopolymer Tg: 97°C), isobornyl methacrylate (homopolymer Tg: 110°C), tetrahydrofurfuryl methacrylate (homopolymer Tg: 35°C), vinyl acetate (homopolymer Tg: 29°C), and styrene (homopolymer Tg: 100°C).

[0055] The content of the structural units derived from monomers having no crosslinkable functional groups and a homopolymer Tg of 0°C or higher in the (meth)acrylic copolymer is preferably 0.1% by mass at the lower limit and 70% by mass at the upper limit. By having the content of the structural units derived from monomers having no crosslinkable functional groups and a homopolymer Tg of 0°C or higher be 0.1% by mass or higher, higher shear adhesive strength can be exhibited. By having the content of the structural units derived from monomers having no crosslinkable functional groups and a homopolymer Tg of 0°C or higher be 70% by mass or lower, higher adhesive strength can be exhibited. The content of the structural units derived from monomers having no crosslinkable functional groups and a homopolymer Tg of 0°C or higher is more preferably 1% by mass at the lower limit and 50% by mass at the upper limit, and even more preferably 3% by mass at the lower limit and 30% by mass at the upper limit. Examples of the content of the structural unit derived from a monomer having no crosslinkable functional group and a homopolymer Tg of 0°C or higher include 0.1% by mass to 70% by mass, 0.1% by mass to 50% by mass, 0.1% by mass to 30% by mass, 1% by mass to 70% by mass, 1% by mass to 50% by mass, 1% by mass to 30% by mass, 3% by mass to 70% by mass, 3% by mass to 50% by mass, and 3% by mass to 30% by mass. The content of the structural unit derived from a monomer having no crosslinkable functional group and a homopolymer Tg of 0°C or higher can be determined by mass spectrometry and / or nuclear magnetic resonance spectroscopy ( １ H-NMR, １３C-NMR, etc.) and calculation can be made from the integrated intensity ratio of hydrogen peaks derived from a monomer that does not have the above-mentioned crosslinkable functional group and has a homopolymer Tg of 0° C. or higher.

[0056] The above-mentioned monomer having a crosslinkable functional group and other monomers preferably contain biologically derived materials, but may also be composed solely of petroleum-derived materials. Theoretically, it is also possible for all of the acrylic monomers constituting the above-mentioned (meth)acrylic copolymer to be monomers containing biologically derived materials. From the viewpoint of cost and productivity of the pressure-sensitive adhesive composition, it is also possible to adopt a monomer containing a relatively inexpensive and easily available biologically derived material and combine it with a monomer composed solely of petroleum-derived materials.

[0057] The weight-average molecular weight of the (meth)acrylic copolymer can be, for example, in the range of 30,000 to 2,000,000. The preferred lower limit of the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 300,000, and the preferred upper limit is 1,500,000. When the weight-average molecular weight of the (meth)acrylic copolymer is 300,000 or more, the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape is further improved. Furthermore, the holding performance of the pressure-sensitive adhesive tape at high temperatures is further improved. When the weight-average molecular weight of the (meth)acrylic copolymer is 1,500,000 or less, the pressure-sensitive adhesive layer has appropriate flexibility, enabling it to absorb even larger impacts, and the resulting pressure-sensitive adhesive tape has superior impact resistance. The more preferred lower limit of the weight-average molecular weight of the (meth)acrylic copolymer is 500,000, the more preferred upper limit is 1,400,000, the even more preferred lower limit is 700,000, the even more preferred upper limit is 1,300,000, the even more preferred lower limit is 800,000, and the particularly preferred lower limit is 900,000. Examples of the range of the weight average molecular weight of the (meth)acrylic copolymer include ranges of 300,000 to 1,500,000, 300,000 to 1,400,000, 300,000 to 1,300,000, 500,000 to 1,500,000, 500,000 to 1,400,000, 500,000 to 1,300,000, 700,000 to 1,500,000, 700,000 to 1,400,000, 700,000 to 1,300,000, 800,000 to 1,500,000, 800,000 to 1,400,000, 800,000 to 1,300,000, 900,000 to 1,500,000, 900,000 to 1,400,000, and 900,000 to 1,300,000.

[0058] The ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the (meth)acrylic copolymer (polydispersity, Mw / Mn) is preferably 7.0 at its upper limit. When the polydispersity of the (meth)acrylic copolymer is 7.0 or less, the proportion of low-molecular-weight components contained in the pressure-sensitive adhesive layer is reduced, thereby further improving the heat resistance of the resulting pressure-sensitive adhesive tape. A more preferred upper limit of the polydispersity of the (meth)acrylic copolymer is 5.0. The polydispersity of the (meth)acrylic copolymer is not particularly limited, but a preferred lower limit is 1.1. When the polydispersity of the (meth)acrylic copolymer is 1.1 or more, excessive reduction in the tackiness of the pressure-sensitive adhesive layer can be suppressed, thereby improving the impact resistance of the resulting pressure-sensitive adhesive tape. A more preferred lower limit of the polydispersity of the (meth)acrylic copolymer (Mw / Mn) is 2.0. The polydispersity of the (meth)acrylic copolymer may be in the range of, for example, 1.1 to 7.0, 1.1 to 5.0, 20 to 70,000, or 20 to 50,000.

[0059] The (meth)acrylic copolymer more preferably has a weight-average molecular weight of 300,000 or more and 1,500,000 or less and a polydispersity of 7.0 or less. When the weight-average molecular weight and polydispersity of the (meth)acrylic copolymer satisfy these ranges, the resulting pressure-sensitive adhesive tape can be balanced between impact absorption and heat resistance.

[0060] In this specification, the weight average molecular weight is a weight average molecular weight calculated in terms of standard polystyrene by GPC (Gel Permeation Chromatography). Specifically, the (meth)acrylic copolymer is diluted 50 times with tetrahydrofuran (THF), 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 (meth)acrylic copolymer is measured, and this value is taken as the weight average molecular weight and number average molecular weight (Mn) of the (meth)acrylic copolymer. Examples of the gel permeation chromatograph include the 2690 Separations Module (manufactured by Waters Corporation). Furthermore, the polydispersity (Mw / Mn) can be calculated using the weight average molecular weight (Mw) and number average molecular weight (Mn) thus obtained.

[0061] Examples of methods for adjusting the weight average molecular weight of the (meth)acrylic copolymer include a method of changing the type or amount of a polymerization initiator or the monomer concentration during the polymerization reaction, a method of adding a small amount of a chain transfer agent such as dodecyl mercaptan, a method of changing the type of polymerization solvent to control chain transfer to the solvent, and a method of changing the temperature and time during polymerization.

[0062] The (meth)acrylic copolymer can be obtained by polymerizing a mixture of constituent monomers as raw materials through a radical reaction in the presence of a polymerization initiator. Examples of the radical reaction include living radical polymerization and free radical polymerization. Living radical polymerization produces copolymers with more uniform molecular weight and composition than free radical polymerization, and can suppress the generation of low-molecular-weight components, etc., resulting in a pressure-sensitive adhesive composition that exhibits stronger cohesive strength and therefore better adhesion to the adherend. Conventional methods can be used to polymerize the monomer mixture, including solution polymerization (boiling point polymerization or constant temperature polymerization), UV polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, solution polymerization and UV polymerization are preferred because they result in a pressure-sensitive adhesive composition that exhibits better adhesion to the adherend. When solution polymerization is used to polymerize the monomer mixture, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, dimethyl sulfoxide, ethanol, acetone, and diethyl ether.

[0063] 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. Furthermore, when the radical reaction is carried out by living radical polymerization, examples of the polymerization initiator include organotellurium polymerization initiators. The organotellurium polymerization initiator is not particularly limited as long as it is one that is generally used in living radical polymerization, and examples thereof include organotellurium compounds, organotelluride compounds, etc. In addition to the organotellurium polymerization initiator, the azo compound may also be used in the living radical polymerization in order to accelerate the polymerization rate.

[0064] The preferred lower limit of the content of the (meth)acrylic copolymer in the pressure-sensitive adhesive composition is 50% by mass, and the preferred upper limit is 90% by mass. When the content of the (meth)acrylic copolymer is within this range, the resulting pressure-sensitive adhesive tape has excellent heat resistance and excellent impact resistance against various impacts. A more preferred lower limit of the content of the (meth)acrylic copolymer is 55% by mass, and a more preferred upper limit is 80% by mass. Examples of the range of the content of the (meth)acrylic copolymer include 50% by mass or more and 90% by mass or less, 50% by mass or more and 80% by mass or less, 55% by mass or more and 90% by mass or less, and 55% by mass or more and 80% by mass or less.

[0065] The pressure-sensitive adhesive composition preferably contains a tackifier. When the pressure-sensitive adhesive composition contains a tackifier, the pressure-sensitive adhesive layer has superior adhesive strength.

[0066] The tackifier is not particularly limited, and examples thereof include rosin-based tackifiers, rosin ester-based tackifiers, terpene-based tackifiers, coumarone-indene-based tackifiers, alicyclic saturated hydrocarbon-based tackifiers, C5-based petroleum tackifiers, C9-based petroleum tackifiers, C5-C9 copolymer-based petroleum tackifiers, and acrylic tackifiers. These tackifiers may be used alone or in combination of two or more. Among these, from the viewpoint of improving suitability for fixing an adherend having a curved portion, it is preferable to include at least one selected from the group consisting of rosin ester-based tackifiers, terpene-based tackifiers, and acrylic tackifiers, and it is more preferable to include a rosin ester-based tackifier and a terpene-based tackifier.

[0067] Examples of the rosin-based tackifier include rosin-based resins and rosin polyol-based resins. Examples of the rosin ester-based tackifier include rosin ester-based resins, polymerized rosin ester-based resins, and hydrogenated rosin ester-based resins. Examples of the terpene-based tackifier include terpene-based resins and terpene phenol-based resins. The rosin ester-based tackifier and the terpene-based tackifier are preferably derived from living organisms. Examples of the rosin ester-based tackifier derived from living organisms include rosin ester-based tackifiers derived from natural resins such as pine resin. Examples of the terpene-based tackifier derived from living organisms include terpene-based tackifiers derived from plant essential oils.

[0068] Specific examples of the rosin ester tackifier include Pencel D-135, Pine Crystal KE-359, Ester Gum AA-V, and Ester Gum H (all manufactured by Arakawa Chemical Industries, Ltd.). Specific examples of the terpene tackifier include YS Resin PX1250 and YS Polystar G150 (all manufactured by Yasuhara Chemical Co., Ltd.).

[0069] The acrylic tackifier comprises a (meth)acrylic compound having a weight-average molecular weight of less than 30,000. Examples of the (meth)acrylic compound having a weight-average molecular weight of less than 30,000 include an acrylic oligomer having a weight-average molecular weight of less than 30,000 and an acrylic monomer having a weight-average molecular weight of less than 30,000. Of these, an acrylic oligomer having a weight-average molecular weight of less than 30,000 is preferred.

[0070] The weight-average molecular weight of the acrylic oligomer used as the acrylic tackifier is less than 30,000. The weight-average molecular weight of the acrylic oligomer is preferably 1,000 or more and less than 30,000. When the weight-average molecular weight of the acrylic oligomer is within the above range, the adhesive strength of the resulting pressure-sensitive adhesive composition is further improved. The weight-average molecular weight of the acrylic oligomer is more preferably 1,500 or more and less than 20,000, and even more preferably 2,000 or more and less than 10,000. The weight-average molecular weight of the acrylic oligomer can be measured by the same method as the method for measuring the weight-average molecular weight of the (meth)acrylic copolymer described above.

[0071] The glass transition temperature of the acrylic oligomer used as the acrylic tackifier preferably has a lower limit of 0°C and an upper limit of 300°C. When the glass transition temperature of the acrylic oligomer is within the above range, the adhesive strength of the resulting pressure-sensitive adhesive composition is further improved. The lower limit of the glass transition temperature of the acrylic oligomer is more preferably 20°C, and even more preferably 40°C. Examples of the glass transition temperature of the acrylic oligomer include 0°C or higher and 300°C or lower, 20°C or higher and 300°C or lower, and 40°C or higher and 300°C or lower. The glass transition temperature of the acrylic oligomer can be measured, for example, by differential scanning calorimetry under a nitrogen atmosphere (nitrogen flow, flow rate 50 mL / min) according to JIS K6240:2011, at a measurement temperature of -100°C to 200°C and a heating rate of 10°C / min.

[0072] Examples of the constituent monomers of the acrylic oligomer and the acrylic monomer include the same monomers as those used in the constituent units derived from the alkyl(meth)acrylate, the constituent units derived from the monomers having a crosslinkable functional group, and the constituent units derived from other monomers in the (meth)acrylic copolymer described above.

[0073] Examples of the constituent monomers of the acrylic oligomer and the acrylic monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, and isopropyl (meth)acrylate. Preferred examples include alkyl (meth)acrylates such as sononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate; esters of (meth)acrylic acid and alicyclic alcohols (alicyclic hydrocarbon group-containing (meth)acrylates) such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate; and (meth)acrylates obtained from terpene compound derivative alcohols. The acrylic oligomer preferably contains, as a monomer unit, an acrylic monomer having a relatively bulky structure, such as an alkyl (meth)acrylate having a branched alkyl group, such as isobutyl (meth)acrylate or t-butyl (meth)acrylate; an ester of (meth)acrylic acid and an alicyclic alcohol, such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, or dicyclopentanyl (meth)acrylate (an alicyclic hydrocarbon group-containing (meth)acrylate); or a (meth)acrylate having a cyclic structure, such as an aryl (meth)acrylate, such as phenyl (meth)acrylate or benzyl (meth)acrylate, from the viewpoint of further improving the adhesiveness of the pressure-sensitive adhesive composition. In addition to the (meth)acrylate monomer, a monomer having a crosslinkable functional group can be used as a constituent monomer component of the acrylic oligomer.Suitable examples of the monomer having a crosslinkable functional group include monomers having a nitrogen atom-containing ring (typically a nitrogen atom-containing heterocycle) such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; amino group-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate; amide group-containing monomers such as N,N-diethyl (meth)acrylamide; carboxy group-containing monomers such as AA and MAA; and hydroxy group-containing monomers such as 2-hydroxyethyl (meth)acrylate. These monomers having a crosslinkable functional group can be used alone or in combination of two or more. Among these, carboxy group-containing monomers are preferred, and AA is particularly preferred. For example, by using a carboxy group-containing monomer as the monomer having a crosslinkable functional group, the adhesive strength to highly polar adherends can be improved.

[0074] The acrylic oligomer can be synthesized, for example, by the same method as that for the (meth)acrylic copolymer described above. Alternatively, a commercially available acrylic tackifier may be used.

[0075] The tackifier preferably contains a tackifier having a softening point of 80°C or higher and 170°C or lower. By containing a tackifier having a softening point of 80°C or higher and 170°C or lower, it becomes easier to adjust the glass transition temperature of the pressure-sensitive adhesive layer to within the above-mentioned range, and the obtained pressure-sensitive adhesive tape has better heat resistance. The softening point of the tackifier is more preferably 90°C in lower limit, more preferably 160°C in upper limit, even more preferably 100°C in lower limit, and even more preferably 150°C in upper limit. Examples of the softening point range of the tackifier include 80°C in higher and 170°C in lower, 80°C in higher and 160°C in lower, 80°C in higher and 150°C in lower, 90°C in higher and 170°C in lower, 90°C in higher and 160°C in lower, 90°C in higher and 150°C in lower, 100°C in higher and 170°C in lower, 100°C in higher and 160°C in lower, and 100°C in higher and 150°C in lower. In this specification, the "softening point" refers to a softening point measured by a method in accordance with JIS K 2207 (ring and ball method).

[0076] The tackifier preferably contains a tackifier having a hydroxyl value of 20 mgKOH / g or more and 150 mgKOH / g or less. By containing a tackifier having a hydroxyl value of 20 mgKOH / g or more and 150 mgKOH / g or less, the degree of crosslinking of the pressure-sensitive adhesive layer is easily increased, thereby further improving the heat resistance and adherend selectivity of the resulting pressure-sensitive adhesive tape. The hydroxyl value of the tackifier is more preferably 30 mgKOH / g (lower limit), more preferably 140 mgKOH / g (upper limit), even more preferably 40 mgKOH / g (lower limit), and even more preferably 130 mgKOH / g (upper limit). Examples of the hydroxyl value range of the tackifier include 20 mgKOH / g or more and 150 mgKOH / g or less, 20 mgKOH / g or more and 140 mgKOH / g or less, 20 mgKOH / g or more and 130 mgKOH / g or less, 30 mgKOH / g or more and 150 mgKOH / g or less, 30 mgKOH / g or more and 140 mgKOH / g or less, 30 mgKOH / g or more and 130 mgKOH / g or less, 40 mgKOH / g or more and 150 mgKOH / g or less, 40 mgKOH / g or more and 140 mgKOH / g or less, 40 mgKOH / g or more and 130 mgKOH / g or less, etc. The hydroxyl value can be measured according to JIS K1557 (phthalic anhydride method).

[0077] In the pressure-sensitive adhesive composition, the preferred lower limit of the tackifier content per 100 parts by mass of the (meth)acrylic copolymer is 10 parts by mass, and the preferred upper limit is 50 parts by mass. When the tackifier content is 10 parts by mass or more, it becomes easier to adjust the glass transition temperature of the pressure-sensitive adhesive layer within the above-mentioned range, and the resulting pressure-sensitive adhesive tape has better heat resistance. When the tackifier content is 50 parts by mass or less, it is possible to prevent the glass transition temperature of the pressure-sensitive adhesive layer from rising too much, and it becomes possible to absorb even larger impacts, and the resulting pressure-sensitive adhesive tape has better impact resistance. A more preferred lower limit of the tackifier content is 15 parts by mass, a more preferred upper limit is 45 parts by mass, an even more preferred lower limit is 20 parts by mass, an even more preferred upper limit is 40 parts by mass, and an even more preferred lower limit is 30 parts by mass. Examples of the range of the content of the tackifier include 10 parts by mass or more and 50 parts by mass or less, 10 parts by mass or more and 45 parts by mass or less, 10 parts by mass or more and 40 parts by mass or less, 15 parts by mass or more and 50 parts by mass or less, 15 parts by mass or more and 45 parts by mass or less, 15 parts by mass or more and 40 parts by mass or less, 20 parts by mass or more and 50 parts by mass or less, 20 parts by mass or more and 45 parts by mass or less, 20 parts by mass or more and 40 parts by mass or less, 30 parts by mass or more and 50 parts by mass or less, 30 parts by mass or more and 45 parts by mass or less, and 30 parts by mass or more and 40 parts by mass or less.

[0078] When the pressure-sensitive adhesive composition contains the acrylic tackifier, the preferred lower limit of the content of the acrylic tackifier relative to 100 parts by mass of the (meth)acrylic copolymer is 0.1 parts by mass, and the preferred upper limit is 50 parts by mass. Having the acrylic tackifier content within this range facilitates a design that improves suitability for fixing an adherend having a curved portion. A more preferred lower limit of the acrylic tackifier content is 1 part by mass, and a more preferred upper limit is 30 parts by mass. Examples of the range of the content of the acrylic tackifier include 0.1 parts by mass or more and 50 parts by mass or less, 0.1 parts by mass or more and 30 parts by mass or less, 1 part by mass or more and 50 parts by mass or less, and 1 part by mass or more and 30 parts by mass or less.

[0079] The pressure-sensitive adhesive composition preferably contains a crosslinking agent from the viewpoint of appropriately adjusting the degree of crosslinking. Examples of the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, and a metal chelate-type crosslinking agent. In particular, the crosslinking agent preferably contains at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent. By including at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent, the pressure-sensitive adhesive layer more easily forms a crosslinked structure, thereby providing appropriate bulk strength and resulting in superior handleability of the resulting pressure-sensitive adhesive tape. It is also more preferable that the crosslinking agent contains an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent. The crosslinking agent may be used alone or in combination of two or more types. When two or more types of crosslinking agents are used in combination, two or more types of the same type of crosslinking agent may be used (for example, two types of isocyanate-based crosslinking agents may be used), or one or more types of different types of crosslinking agents may be used in combination (for example, one or more types of isocyanate-based crosslinking agents and one or more types of epoxy-based crosslinking agents may be used).

[0080] In the pressure-sensitive adhesive composition, the preferred lower limit of the content of the crosslinking agent relative to 100 parts by mass of the (meth)acrylic copolymer is 0.01 parts by mass, and the preferred upper limit is 10 parts by mass. When the content of the crosslinking agent is 0.01 parts by mass or more, the pressure-sensitive adhesive layer more easily forms a crosslinked structure, providing appropriate bulk strength, thereby further improving the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape. Furthermore, the pressure-sensitive adhesive tape has improved retention performance at high temperatures. When the content of the crosslinking agent is 10 parts by mass or less, the pressure-sensitive adhesive layer has appropriate flexibility, allowing it to absorb even larger impacts, resulting in the resulting pressure-sensitive adhesive tape having superior impact resistance. A more preferred lower limit of the content of the crosslinking agent is 0.1 parts by mass, a more preferred upper limit is 8.0 parts by mass, an even more preferred lower limit is 0.2 parts by mass, an even more preferred upper limit is 7.5 parts by mass, an even more preferred upper limit is 7.0 parts by mass, and a particularly preferred upper limit is 5.0 parts by mass. The content of the crosslinking agent can be, for example, from 0.01 to 10 parts by mass, from 0.01 to 8.0 parts by mass, from 0.01 to 7.5 parts by mass, from 0.01 to 7.0 parts by mass, from 0.01 to 5.0 parts by mass, from 0.1 to 10 parts by mass, from 0.1 to 8.0 parts by mass, from 0.1 to 7.5 parts by mass, from 0.1 to 7.0 parts by mass, from 0.1 to 5.0 parts by mass, from 0.2 to 10 parts by mass, from 0.2 to 8.0 parts by mass, from 0.2 to 7.5 parts by mass, from 0.2 to 7.0 parts by mass, from 0.2 to 5.0 parts by mass, etc. In this specification, the term "content of crosslinking agent" refers to the content of the solid content of the crosslinking agent.

[0081] The pressure-sensitive adhesive composition may further contain a crosslinking catalyst for accelerating crosslinking by the crosslinking agent. Examples of the crosslinking catalyst include crosslinking catalysts for the isocyanate-based crosslinking agents, such as dibutyltin dilaurate, dibutyltin diacetate, and dioctyltin dilaurate.

[0082] The pressure-sensitive adhesive composition may contain additives such as a silane coupling agent, a plasticizer, a softener, a filler, a dye, or a pigment, as needed, within the scope of not impairing the object of the present invention.

[0083] The preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 20% by mass, and the preferred upper limit is 70% by mass. When the gel fraction of the pressure-sensitive adhesive layer is 20% by mass or more, the pressure-sensitive adhesive layer is more likely to form a crosslinked structure, and the pressure-sensitive adhesive layer has appropriate bulk strength, thereby further improving the heat resistance of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive tape. Furthermore, the pressure-sensitive adhesive tape has improved retention performance at high temperatures. When the gel fraction of the pressure-sensitive adhesive layer is 70% by mass or less, the pressure-sensitive adhesive layer has appropriate flexibility, allowing it to absorb even larger impacts, and the resulting pressure-sensitive adhesive tape has superior impact resistance. The more preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 25% by mass, and the more preferred upper limit is 60% by mass, with an even more preferred lower limit being 30% by mass and an even more preferred upper limit being 50% by mass. Examples of the gel fraction range of the pressure-sensitive adhesive layer include 20% by mass or more and 70% by mass or less, 20% by mass or more and 60% by mass or less, 20% by mass or more and 50% by mass or less, 25% by mass or more and 70% by mass or less, 25% by mass or more and 60% by mass or less, 25% by mass or more and 50% by mass or less, 30% by mass or more and 70% by mass or less, 30% by mass or more and 60% by mass or less, and 30% by mass or more and 50% by mass or less. The gel fraction of the pressure-sensitive adhesive layer is measured by the following method, etc. That is, first, a pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer is cut into a flat rectangular shape with a width of 20 mm and a length of 40 mm to prepare a test piece, and the test piece 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 test piece after drying is measured, and the gel fraction is calculated using the following formula (I). Note that no release film for protecting the pressure-sensitive adhesive layer is laminated on the test piece. In addition, when the pressure-sensitive adhesive tape is a non-support type tape that does not have a substrate layer, the measurement is carried out using a test piece obtained by attaching the tape to a substrate and cutting it, or by measuring the W in the following formula (I) without using a substrate layer. ０ The calculation is performed assuming that the gel fraction is 0. Gel fraction (mass%) = 100 × (W ２ -W ０) / (W １ -W ０ ) (I) (W ０ : Mass of the base material layer, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0084] The preferred lower limit of the bio-derived carbon content in the pressure-sensitive adhesive layer is 10%. When the bio-derived carbon content in the pressure-sensitive adhesive layer is 10% or more, the resulting pressure-sensitive adhesive tape is excellent in terms of saving petroleum resources and reducing carbon dioxide emissions, and can reduce the environmental burden. The more preferred lower limit of the bio-derived carbon content in the pressure-sensitive adhesive layer is 40%, and the even more preferred lower limit is 60%. The upper limit of the bio-derived carbon content in the pressure-sensitive adhesive layer is not particularly limited and may be 100%, but is, for example, 95% or 90%. Examples of ranges for the bio-derived carbon content in the pressure-sensitive adhesive layer include 10% or more and 100% or less, 10% or more and 95% or less, 10% or more and 90% or less, 40% or more and 100% or less, 40% or more and 95% or less, 40% or more and 90% or less, 60% or more and 100% or less, 60% or more and 95% or less, and 60% or more and 90% or less. Biologically derived carbon contains a certain percentage of the radioactive isotope (C-14), whereas petroleum-derived carbon contains almost no C-14. Therefore, the "biologically derived carbon content" in this specification can be calculated by measuring the concentration of C-14 contained in the PSA layer. Specifically, it can be measured in accordance with ASTM D6866-24, a standard widely used in the bioplastics industry.

[0085] The preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 5 μm. When the thickness of the pressure-sensitive adhesive layer is 5 μm or more, the impact absorption properties of the pressure-sensitive adhesive layer are further improved, and the impact resistance of the resulting pressure-sensitive adhesive tape is further improved. The more preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 25 μm, and even more preferred lower limit is 40 μm. The preferred upper limit of the thickness of the pressure-sensitive adhesive layer is 100 μm. When the thickness of the pressure-sensitive adhesive layer is 100 μm or less, the holding performance of the resulting pressure-sensitive adhesive tape is further improved. The more preferred upper limit of the thickness of the pressure-sensitive adhesive layer is 80 μm, and even more preferred upper limit is 60 μm. Examples of the thickness range of the pressure-sensitive adhesive layer include 5 μm or more and 100 μm or less, 5 μm or more and 80 μm or less, 5 μm or more and 60 μm or less, 25 μm or more and 100 μm or less, 25 μm or more and 80 μm or less, 25 μm or more and 60 μm or less, 40 μm or more and 100 μm or less, 40 μm or more and 80 μm or less, and 40 μm or more and 60 μm or less.

[0086] The pressure-sensitive adhesive tape may have a layer other than the pressure-sensitive adhesive layer.

[0087] The pressure-sensitive adhesive tape may be a non-support type tape that does not have a base layer, or a support type tape that has a base layer. When the pressure-sensitive adhesive tape is a support type tape that has a base layer, it may be a single-sided pressure-sensitive adhesive tape that has the pressure-sensitive adhesive layer on one side of the base layer, or a double-sided pressure-sensitive adhesive tape that has the pressure-sensitive adhesive layer on at least one side of the base layer.

[0088] When the pressure-sensitive adhesive tape is a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both sides of a base layer, it is sufficient that the glass transition temperature and half width of the loss tangent of at least one of the pressure-sensitive adhesive layers satisfy the above-mentioned ranges, but it is preferable that the glass transition temperature and half width of the loss tangent of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive on both sides satisfy the above-mentioned ranges.

[0089] Examples of substrates used for the substrate layer include films, nonwoven fabrics, and foam substrates. The substrate used for the substrate layer is preferably a substrate made of a biologically-derived material, from the viewpoint of increasing the content of biologically-derived carbon in the entire pressure-sensitive adhesive tape. Examples of biologically-derived materials include polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS), polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetyl cellulose (TAC), cellulose, and polyamide (PA), which are derived from plants.

[0090] Furthermore, from the perspective of reducing the use of new petroleum resources and reducing the environmental burden by suppressing carbon dioxide emissions, substrates made from recycled resources may be used. Examples of resource recycling methods include collecting waste materials such as packaging containers, home appliances, automobiles, construction materials, and food, as well as waste generated during manufacturing processes, and then cleaning, decontaminating, or decomposing the extracted materials by heating or fermentation to reuse them as raw materials. Examples of substrates made from recycled resources include films and nonwoven fabrics made from PET, PBT, PE, PP, PA, etc., which are made from recycled plastics that have been re-resinized. Furthermore, the collected waste materials may be burned and used as thermal energy for the production of substrates and their raw materials. The oils and fats contained in the collected waste materials may be mixed with petroleum, fractionated, and purified, and then used as raw materials.

[0091] The substrate used in the substrate layer may contain a foam substrate from the viewpoint of improving impact resistance. The foam substrate is preferably a foam substrate containing at least one selected from the group consisting of PE, PP, and PU, and a foam substrate containing PE is more preferred from the viewpoint of achieving a high level of both flexibility and strength. Examples of the constituent of the foam substrate containing PE include PE made from sugarcane.

[0092] A preferred method for producing the foam base material is, for example, to prepare a foamable resin composition containing a PE resin containing sugarcane-derived PE and a foaming agent, and then foam the foaming agent when extruding the foamable resin composition into a sheet using an extruder, and optionally crosslink the resulting polyolefin foam.

[0093] The preferred lower limit of the thickness of the foam substrate is 50 μm, and the preferred upper limit is 5000 μm. By having the thickness of the foam substrate within this range, it is possible to exhibit high impact resistance while exhibiting high flexibility that allows it to be adhered to the shape of the adherend. The more preferred upper limit of the thickness of the foam substrate is 1000 μm, and even more preferred upper limit is 300 μm. Examples of the thickness of the foam substrate include 50 μm or more and 5000 μm or less, 50 μm or more and 1000 μm or less, and 50 μm or more and 300 μm or less.

[0094] The substrate used in the substrate layer is preferably a film containing PES or a film containing PA from the viewpoint of substrate strength. Furthermore, a film containing PA is preferred from the viewpoint of heat resistance and oil resistance. Examples of PA include nylon 11, nylon 1010, nylon 610, nylon 510, and nylon 410, which are made from castor oil, and nylon 56, which is made from cellulose.

[0095] The preferred lower limit of the thickness of the substrate is 50 μm, and the preferred upper limit is 5000 μm. By having the thickness of the substrate within this range, high flexibility can be exhibited, allowing the substrate to be adhered closely to the shape of the adherend and bonded. The more preferred upper limit of the thickness of the substrate is 1000 μm, and even more preferred upper limit is 300 μm. The thickness range of the substrate can be, for example, 50 μm or more and 5000 μm or less, 50 μm or more and 1000 μm or less, or 50 μm or more and 300 μm or less.

[0096] The pressure-sensitive adhesive tape preferably has a lower limit of 3 μm and an upper limit of 6000 μm for the total thickness (the sum of the thickness of the base layer and the thickness of the pressure-sensitive adhesive layer) of the pressure-sensitive adhesive tape. Having the total thickness of the pressure-sensitive adhesive tape in this range increases the adhesive strength of the resulting pressure-sensitive adhesive tape. The upper limit of the total thickness of the pressure-sensitive adhesive tape is more preferably 1200 μm, and even more preferably 500 μm. Examples of the range of the total thickness of the pressure-sensitive adhesive tape include ranges of 3 μm or more and 6000 μm or less, 3 μm or more and 1200 μm or less, and 3 μm or more and 500 μm or less.

[0097] The method for producing the pressure-sensitive adhesive tape is not particularly limited, and it can be produced by a conventionally known production method. For example, in the case of a double-sided pressure-sensitive adhesive tape, the following method can be mentioned. First, a pressure-sensitive adhesive composition A is prepared by adding a solvent to the (meth)acrylic copolymer and, if necessary, a tackifier, a crosslinking agent, etc. The obtained pressure-sensitive adhesive composition A is applied to the surface of a substrate, and the solvent in the composition is completely dried and removed by heating to form a pressure-sensitive adhesive layer A. Next, a release film is superimposed on the formed pressure-sensitive adhesive layer A with its release-treated surface facing the pressure-sensitive adhesive layer A. Next, a release film separate from the above release film is prepared, and pressure-sensitive adhesive composition B prepared in the same manner as the pressure-sensitive adhesive composition A is applied to the release-treated surface of this release film, and the solvent in the composition is completely dried and removed to produce a laminate film in which pressure-sensitive adhesive layer B is formed on the surface of the release film. The obtained laminate film is superimposed on the back surface of the substrate on which pressure-sensitive adhesive layer A has been formed, with the pressure-sensitive adhesive layer B facing the back surface of the substrate, to produce a laminate. Then, by pressing the laminate with a rubber roller or the like, a double-sided adhesive tape can be obtained which has adhesive layers on both sides of the substrate and in which the surfaces of the adhesive layers are covered with release films.

[0098] Alternatively, two sets of laminate films may be prepared in a similar manner, and these laminate films may be superimposed on each of both surfaces of a substrate with the pressure-sensitive adhesive layer of the laminate film facing the substrate to prepare a laminate. This laminate may then be pressed with a rubber roller or the like to obtain a double-sided pressure-sensitive adhesive tape having pressure-sensitive adhesive layers on both surfaces of the substrate and in which the surfaces of the pressure-sensitive adhesive layers are covered with release films.

[0099] The pressure-sensitive adhesive tape may be colored. The color of the pressure-sensitive adhesive tape is not particularly limited, and examples thereof include white, black, gray, etc. Among these, black and gray are preferred from the viewpoint of further improving the light-shielding properties of the resulting pressure-sensitive adhesive tape.

[0100] The pressure-sensitive adhesive tape can be colored, for example, by incorporating a pigment (dye) into the pressure-sensitive adhesive composition. Examples of the pigment include carbon black ("Multilac A903 Black" manufactured by Toyocolor Co., Ltd.).

[0101] The application of the pressure-sensitive adhesive tape is not particularly limited, but it is preferably used for fixing electronic components or vehicle-mounted components. Specifically, the pressure-sensitive adhesive tape can be suitably used for adhesively fixing electronic components in large portable electronic devices, adhesively fixing vehicle-mounted components (e.g., vehicle panels), etc. In particular, the pressure-sensitive adhesive tape has excellent heat resistance and excellent impact resistance against various impacts, so it can be suitably used for adhesively fixing electronic components in portable electronic devices. Furthermore, from the viewpoint that the pressure-sensitive adhesive tape can exhibit impact resistance against various impacts without increasing the thickness of the pressure-sensitive adhesive layer, it can be suitably used for adhesively fixing electronic components in thin portable electronic devices.

[0102] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape that has excellent heat resistance and excellent impact resistance against various types of impact.

[0103] Fig. 1 is a diagram schematically showing a measurement sample used in an impact absorption test; Fig. 2 is a diagram schematically showing an impact absorption test; Fig. 3 is a diagram schematically showing a high temperature retention test; Fig. 4 is a diagram schematically showing a flip-up test; Fig. 5 is a diagram schematically showing an example of a measurement sample in which a floating height occurred after a flip-up test.

[0104] The following examples further illustrate aspects of the present invention, but the present invention is not limited to these examples. The materials used in the examples and comparative examples are as follows.

[0105] <n-Hexyl acrylate containing bio-derived carbon> Linoleic acid derived from castor oil was converted to linoleic acid hydroperoxide using lipoxygenase, and then a mixture containing n-hexylaldehyde was obtained using isomerase. The resulting mixture was distilled to obtain n-hexylaldehyde containing bio-derived carbon. The obtained n-hexylaldehyde containing bio-derived carbon was then hydrogenated to obtain n-hexyl alcohol containing bio-derived carbon. The obtained n-hexyl alcohol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare n-hexyl acrylate containing bio-derived carbon.

[0106] <n-heptyl acrylate containing bio-derived carbon> Ricinoleic acid derived from castor oil was cracked to obtain a mixture containing undecylenic acid and n-heptyl alcohol. Next, undecylenic acid was separated from the obtained mixture by distillation to obtain n-heptyl alcohol containing bio-derived carbon. The obtained n-heptyl alcohol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare n-heptyl acrylate containing bio-derived carbon.

[0107] <1-Methylheptyl acrylate containing bio-derived carbon> Ricinoleic acid derived from castor oil was alkali-fused to obtain a mixture containing sepacic acid and 1-methylheptyl alcohol. Next, sepacic acid was separated from the obtained mixture by distillation to obtain 1-methylheptyl alcohol containing bio-derived carbon. 1-Methylheptyl acrylate containing bio-derived carbon was prepared by esterifying the obtained 1-methylheptyl alcohol containing bio-derived carbon with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.).

[0108] <2-hydroxyethyl acrylate containing bio-derived carbon> Ethanol containing bio-derived carbon was obtained by fermenting sugar contained in sugarcane. The obtained ethanol containing bio-derived carbon was dehydrated to obtain ethylene, which was then oxidized to obtain ethylene oxide, to which water was added to obtain ethylene glycol containing bio-derived carbon. The obtained ethylene glycol containing bio-derived carbon was esterified with acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) to prepare 2-hydroxyethyl acrylate containing bio-derived carbon.

[0109] <Bio-derived carbon-free constituent monomers> Methyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) n-Butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) Acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) 2-Methoxyethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0110] <Tackifiers> Tackifier A: rosin ester tackifier (softening point: 150°C, hydroxyl value: 35 mgKOH / g) Tackifier B: rosin ester tackifier (Arakawa Chemical Industries, Ltd., "Pine Crystal KE-359", softening point: 100°C, hydroxyl value: 40 mgKOH / g) Tackifier C: terpene tackifier (terpene phenol resin) (Yasuhara Chemical Co., Ltd., "YS Polystar G150", softening point: 150°C, hydroxyl value: 130 mgKOH / g) Tackifier D: acrylic tackifier It should be noted that, as the acrylic tackifier, an acrylic oligomer obtained by synthesis by the following method was used. That is, a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a reflux condenser, and a dropping funnel was charged with 95 parts by mass of cyclohexyl methacrylate (CHMA) and 5 parts by mass of acrylic acid (Aa), azobisisobutyronitrile (AIBN 10 parts by mass) as a polymerization initiator, and ethyl acetate as a polymerization solvent, and stirred in a nitrogen stream for 1 hour to remove oxygen from the polymerization system, then heated to 85 ° C. and reacted for 5 hours to obtain an acrylic oligomer with a solids concentration of 50%. In addition, the obtained acrylic oligomer was diluted 50 times with tetrahydrofuran (THF) and the obtained diluted solution was filtered with a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare a measurement sample. This measurement sample was supplied to a gel permeation chromatograph (manufactured by Waters Corporation, "2690 Separations Module"), 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 oligomer was measured to determine the weight-average molecular weight, which was found to be 3,600.

[0111] <Crosslinking agent> Isocyanate-based crosslinking agent (manufactured by Covestro, "Desmodur L-75") Epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, Inc., "Tetrad X")

[0112] <Pigment> Carbon black (Toyo Color Co., Ltd., "Multilac A903 Black")

[0113] Example 1 (1) Production of (meth)acrylic copolymer Ethyl acetate was added as a polymerization solvent to a reaction vessel, and nitrogen was bubbled through the reaction vessel. The reaction vessel was then heated while nitrogen was flowing in to initiate reflux. Subsequently, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile as a polymerization initiator 10 times with ethyl acetate was added to the reaction vessel, and 94.9 parts by mass of 1-methylheptyl acrylate containing bio-derived carbon, 0.1 parts by mass of 2-hydroxyethyl acrylate containing bio-derived carbon, and 5.0 parts by mass of acrylic acid were added dropwise over a period of 2 hours. After completion of the dropwise addition, a polymerization initiator solution prepared by diluting 0.1 parts by mass of azobisisobutyronitrile as a polymerization initiator 10 times with ethyl acetate was again added to the reaction vessel, and the polymerization reaction was carried out for 4 hours to obtain a (meth)acrylic copolymer-containing solution. The obtained (meth)acrylic copolymer-containing solution was diluted 50 times with tetrahydrofuran (THF) and the resulting diluted solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare a measurement sample. This measurement sample was supplied to a gel permeation chromatograph (Waters, "2690 Separations Module") and subjected to GPC measurement 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 to determine the weight average molecular weight. The results are shown in Table 1.

[0114] (2) Production of adhesive tape To the obtained (meth)acrylic copolymer-containing solution, 14.0 parts by mass of tackifier A, 10.0 parts by mass of tackifier B, 10.0 parts by mass of tackifier C, and an isocyanate-based crosslinking agent were added so that the solid content of the crosslinking agent was 4.5 parts by mass per 100 parts by mass of the acrylic copolymer in the (meth)acrylic copolymer-containing solution to prepare an adhesive composition. The obtained adhesive composition was applied to the release-treated surface of a 75 μm-thick release PET film so that the thickness of the adhesive layer after drying would be 19 μm, and then dried at 110 ° C. for 5 minutes to form an adhesive layer. The formed adhesive layer was then bonded to one side of a 12 μm-thick PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002"). Furthermore, an adhesive layer having the same composition and thickness formed by the same method was attached to the other side of the PET film to form an integrated laminate, and then the laminate was cured at 40°C for 48 hours to obtain an adhesive tape having adhesive layers on both sides of the substrate.

[0115] (3) Measurement of gel fraction of adhesive layer The release PET film on one side of the obtained adhesive tape was peeled off, and the tape was cut into a flat rectangular shape with a width of 20 mm and a length of 40 mm. The release PET film on the other side of the adhesive tape was further peeled off to prepare a test piece, and the 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 following formula (I). The results are shown in Table 1. Gel fraction (mass%) = 100 x (W ２ -W ０ ) / (W １ -W ０ ) (I) (W ０ : Mass of the base material layer, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0116] (4) Measurement of the Glass Transition Temperature of the Pressure-Sensitive Adhesive Layer A laminate of approximately 1 mm thick was prepared by laminating the pressure-sensitive adhesive layer before bonding to the substrate PET film, and then cut into a width of 6 mm and a length of 10 mm to obtain a test piece. Next, the obtained test piece was subjected to dynamic viscoelasticity measurement in shear mode under a nitrogen atmosphere at a temperature range of -40°C to 200°C, a heating rate of 5°C / min, a frequency of 1 Hz, and a strain of 0.08%, using a dynamic viscoelasticity measuring device (manufactured by IT Measurement & Control Co., Ltd., "DVA-200"), to obtain the glass transition temperature of the pressure-sensitive adhesive layer. The results are shown in Table 1.

[0117] (5) Measurement of the half-width of the loss tangent peak and the height of the loss tangent peak of the pressure-sensitive adhesive layer The half-width of the loss tangent peak and the height of the loss tangent peak of the pressure-sensitive adhesive layer were obtained from the dynamic viscoelasticity spectrum obtained in the dynamic viscoelasticity measurement in "(4) Glass transition temperature of the pressure-sensitive adhesive layer" above. The results are shown in Table 1.

[0118] (6) Measurement of loss tangent of pressure-sensitive adhesive layer at 65 ° C. The pressure-sensitive adhesive layer before being bonded to the base PET film was stacked to prepare a laminate with a thickness of about 1 mm, and cut into a width of 6 mm and a length of 10 mm to obtain a test piece. The obtained test piece was subjected to dynamic viscoelasticity measurement in shear mode under a nitrogen atmosphere at a measurement temperature of -50 ° C. to 150 ° C., a heating rate of 5 ° C. / min, a frequency of 1 Hz, and a strain of 0.1%, using a dynamic viscoelasticity measuring device (IT Measurement Control Co., Ltd., "DVA-200"), and the results are shown in Table 1.

[0119] (7) Measurement of shear storage modulus of pressure-sensitive adhesive layer at 23°C The shear storage modulus (MPa) of the pressure-sensitive adhesive layer at 23°C was measured by the dynamic viscoelasticity measurement described above in "(6) Measurement of loss tangent of pressure-sensitive adhesive layer at 65°C". The results are shown in Table 1.

[0120] (8) Measurement of shear storage modulus of pressure-sensitive adhesive layer at −15° C. and 80° C. The shear storage modulus of the pressure-sensitive adhesive layer at −15° C. and 80° C. was obtained by the dynamic viscoelasticity measurement in the above-mentioned “(4) Glass transition temperature of pressure-sensitive adhesive layer.” The results are shown in Table 1.

[0121] (Examples 2 to 13, 15 to 28, 30 to 32, 34 to 38, 41, 43, Comparative Examples 1 to 4) Pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1, except that the types and amounts of the monomers constituting the (meth)acrylic copolymer and the types and amounts of the components of the pressure-sensitive adhesive composition were changed to those shown in Tables 1 to 5. Furthermore, in the same manner as in Example 1, the weight-average molecular weight of the (meth)acrylic copolymer, the gel fraction of the pressure-sensitive adhesive layer, the glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the peak height of the loss tangent of the pressure-sensitive adhesive layer, the loss tangent at 65°C of the pressure-sensitive adhesive layer, the shear storage modulus of the pressure-sensitive adhesive layer at 23°C, and the shear storage modulus of the pressure-sensitive adhesive layer at -15°C and 80°C were measured. The results are shown in Tables 1 to 5. In Examples 5, 17 to 18, 22, 27 to 28, and 36 to 37, the types and blending amounts of the components of the pressure-sensitive adhesive composition were changed as shown in Tables 1 to 4, and further, in the above-mentioned "(1) Production of (meth)acrylic copolymer", the amount of polymerization initiator added, etc. were appropriately changed, and pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1.

[0122] Example 14 Pressure-sensitive adhesive tapes were obtained in the same manner as in Examples 2 to 13, 15 to 28, 30 to 32, 34 to 38, 41, and 43, and Comparative Examples 1 to 4, except that the thickness of the pressure-sensitive adhesive layer on each side was changed to 30 μm. Furthermore, the weight-average molecular weight of the (meth)acrylic copolymer, the gel fraction of the pressure-sensitive adhesive layer, the glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the peak height of the loss tangent of the pressure-sensitive adhesive layer, the loss tangent at 65°C of the pressure-sensitive adhesive layer, the shear storage modulus of the pressure-sensitive adhesive layer at 23°C, and the shear storage modulus of the pressure-sensitive adhesive layer at -15°C and 80°C were measured in the same manner as in Example 1. The results are shown in Table 2.

[0123] Example 29 Pressure-sensitive adhesive tapes were obtained in the same manner as in Examples 2 to 13, 15 to 28, 30 to 32, 34 to 38, 41, and 43 and Comparative Examples 1 to 4, except that the substrate used as the substrate layer was changed to a PI (polyimide) film (manufactured by PI Advanced Materials, Inc., "GF," thickness 12 μm). Furthermore, in the same manner as in Example 1, the weight-average molecular weight of the (meth)acrylic copolymer, the gel fraction of the pressure-sensitive adhesive layer, the glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the peak height of the loss tangent of the pressure-sensitive adhesive layer, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the shear storage modulus of the pressure-sensitive adhesive layer at 23°C, and the shear storage modulus of the pressure-sensitive adhesive layer at -15°C and 80°C were measured. The results are shown in Table 3.

[0124] (Example 33) Pressure-sensitive adhesive tapes were obtained in the same manner as in Examples 2 to 13, 15 to 28, 30 to 32, 34 to 38, 41, and 43 and Comparative Examples 1 to 4, except that the substrate used as the substrate layer was changed to a PEN (polyethylene naphthalate) film (manufactured by Toyobo Co., Ltd., "Teonex Q5100," thickness 12 μm). Furthermore, in the same manner as in Example 1, the weight-average molecular weight of the (meth)acrylic copolymer, the gel fraction of the pressure-sensitive adhesive layer, the glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the peak height of the loss tangent of the pressure-sensitive adhesive layer, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the shear storage modulus of the pressure-sensitive adhesive layer at 23°C, and the shear storage modulus of the pressure-sensitive adhesive layer at -15°C and 80°C were measured. The results are shown in Table 3.

[0125] Example 39 A pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that the type and amount of the monomer constituting the (meth)acrylic copolymer and the type and amount of each component of the pressure-sensitive adhesive composition were changed as shown in Table 4. The obtained pressure-sensitive adhesive composition was applied to the release-treated surface of a 75 μm-thick release PET film so that the thickness of the pressure-sensitive adhesive layer after drying would be 38 μm, and then dried at 110°C for 5 minutes. The obtained pressure-sensitive adhesive layer was placed on the release-treated surface of a 75 μm-thick release PET film and aged at 40°C for 48 hours to obtain a pressure-sensitive adhesive tape (non-support type). Furthermore, the weight-average molecular weight of the (meth)acrylic copolymer and the gel fraction of the pressure-sensitive adhesive layer were measured in the same manner as in Example 1. The glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the peak loss tangent of the pressure-sensitive adhesive layer, the peak height of the loss tangent of the pressure-sensitive adhesive layer, the loss tangent at 65°C of the pressure-sensitive adhesive layer, the loss tangent at 65°C of the pressure-sensitive adhesive layer, the shear storage modulus at 23°C of the pressure-sensitive adhesive layer, and the shear storage modulus at -15°C and 80°C of the pressure-sensitive adhesive layer were measured by peeling off the release films from the obtained pressure-sensitive adhesive tapes and overlapping the pressure-sensitive adhesive layers to produce laminates with a thickness of approximately 1 mm for test specimens. The gel fraction of the pressure-sensitive adhesive layer was measured by peeling off the release PET film from one side of the pressure-sensitive adhesive tape, bonding the tape to a 23 μm thick base PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002"), cutting the tape into a flat rectangular shape 20 mm wide and 40 mm long, and then peeling off the release PET film from the other side. The results are shown in Table 4.

[0126] (Example 40) Pressure-sensitive adhesive tapes were obtained in the same manner as in Examples 2 to 13, 15 to 28, 30 to 32, 34 to 38, 41, and 43 and Comparative Examples 1 to 4, except that the substrate used as the substrate layer was changed to PE foam (manufactured by Sekisui Chemical Co., Ltd., "WL02," thickness 150 μm). Furthermore, in the same manner as in Example 1, the weight-average molecular weight of the (meth)acrylic copolymer, the gel fraction of the pressure-sensitive adhesive layer, the glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the peak height of the loss tangent of the pressure-sensitive adhesive layer, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the shear storage modulus of the pressure-sensitive adhesive layer at 23°C, and the shear storage modulus of the pressure-sensitive adhesive layer at -15°C and 80°C were measured. The results are shown in Table 4.

[0127] Example 42 Pressure-sensitive adhesive tapes were obtained in the same manner as in Examples 2 to 13, 15 to 28, 30 to 32, 34 to 38, 41, and 43 and Comparative Examples 1 to 4, except that the thickness of the pressure-sensitive adhesive layer on each side was changed to 5 μm. Furthermore, the weight-average molecular weight of the (meth)acrylic copolymer, the gel fraction of the pressure-sensitive adhesive layer, the glass transition temperature of the pressure-sensitive adhesive layer, the half-width of the loss tangent peak of the pressure-sensitive adhesive layer, the peak height of the loss tangent of the pressure-sensitive adhesive layer, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the loss tangent of the pressure-sensitive adhesive layer at 65°C, the shear storage modulus of the pressure-sensitive adhesive layer at 23°C, and the shear storage modulus of the pressure-sensitive adhesive layer at -15°C and 80°C were measured in the same manner as in Example 1. The results are shown in Table 4.

[0128] The substrates used as the substrate layer in the examples and comparative examples are as follows: PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002", thickness 12 μm) PE foam (manufactured by Sekisui Chemical Co., Ltd., "WL02", thickness 150 μm) PI film (manufactured by PI Advanced Materials, "GF", thickness 12 μm) PEN film (manufactured by Toyobo Co., Ltd., "Teonex Q5100", thickness 12 μm)

[0129] <Evaluation> The pressure-sensitive adhesive tapes obtained in the examples and comparative examples were evaluated by the following methods. The results are shown in Tables 1 to 5.

[0130] (Impact Resistance) The impact resistance of the pressure-sensitive adhesive tape was evaluated by performing an impact absorption test. Figures 1 and 2 are diagrams showing the impact absorption test in schematic form. Specifically, first, a pressure-sensitive adhesive tape 2 cut into a frame shape (outer frame: width 61 mm, length 46 mm, inner frame: width 57 mm, length 42 mm) was bonded to a perforated polycarbonate (PC) plate 3 having a width of 115 mm, a length of 80 mm, and a thickness of 2 mm, with a hole of 50 mm width and 38 mm length in the center. Furthermore, a PC plate 1 having a width of 100 mm, a length of 65 mm, and a thickness of 1 mm was bonded to the other side of the bonded pressure-sensitive adhesive tape 2, and the PC plate 1 was pressed against the other side of the bonded pressure-sensitive adhesive tape 2 using a 5 kg weight for 10 seconds in an environment of 23°C, thereby preparing a measurement sample (see Figure 1). The obtained test sample was placed on a 15 mm wide, 50 mm long, and 35 mm thick SUS block 4 with the perforated surface of the perforated PC board 3 facing vertically upward (i.e., the surface to which the PC board 1 was attached was facing downward), and a test was performed in which a cylindrical 200 g weight was dropped from a height of 50 mm from the measurement sample onto the perforated position of the perforated PC board 3 (in the direction of the arrow in Figure 2) to measure the presence or absence of peeling of the PC board 1. If peeling of the PC board 1 was observed, the drop height H of the weight (50 mm above the measurement sample was defined as H = 0) was recorded. If peeling of the PC board 1 was not observed, the test was repeated under conditions in which the height from which the cylindrical weight was dropped was increased by another 50 mm. Thereafter, the test was repeated, increasing the drop height of the cylindrical weight by 50 mm increments until peeling of the PC board 1 was observed, and the drop height H of the weight at which peeling of the PC board 1 was observed was recorded. The test was performed 10 times, with the test until peeling of the PC board 1 being counted as one test, and the impact resistance of the adhesive tape was evaluated according to the following criteria.・◎: The difference between the maximum and minimum drop heights H measured in 10 tests was within 150 mm, and the average drop height H was 200 mm or more. ・◯: The difference between the maximum and minimum drop heights H measured in 10 tests was within 150 mm, and the average drop height H was 150 mm or more and less than 200 mm. ・△: The difference between the maximum and minimum drop heights H measured in 10 tests was greater than 150 mm and less than 300 mm, and the average drop height H was 150 mm or more. ・×: The difference between the maximum and minimum drop heights H measured in 10 tests was 300 mm or more, or the average drop height H was less than 150 mm.

[0131] (Heat Resistance) A high-temperature retention test was conducted in accordance with JIS Z 0237:2009 to evaluate the heat resistance of the pressure-sensitive adhesive tape. Figure 3 shows a schematic diagram of the high-temperature retention test. Specifically, one side (the side not being measured) of the pressure-sensitive adhesive tape 2 was first lined with a 23 μm-thick polyethylene terephthalate film 5 (manufactured by Futamura Chemical Co., Ltd., "FE2002"), and then cut into a width of 25 mm and a length of 75 mm to prepare a test piece. This test piece was placed so that its adhesive layer (the side being measured) faced a 2 mm-thick, 50 mm-wide, and 80 mm-long SUS304 plate 6 (a SUS304 plate that had been washed with ethanol and then wiped dry). A 2 kg rubber roller was then rolled back and forth on the test piece at a speed of 300 mm / min, and the test piece was bonded to the SUS304 plate 3 so that a portion of the test piece protruded (adhesion area: width 25 mm, length 25 mm). Thereafter, the test sample was cured at 23°C and 50% RH for 20 minutes to prepare a test sample. The test sample was placed in an environment of 80°C and 50% RH and left to stand for 15 minutes. In this environment, a 1.5 kg weight 7 was attached to the polyethylene terephthalate film 5 of the test sample so that a load in the shear direction (lengthwise direction) was applied in accordance with JIS Z 0237:2009. 24 hours after the weight 7 was attached, the amount of displacement in the shear direction from the position where the pressure-sensitive adhesive layer was attached to the SUS304 plate 6 was measured. The heat resistance of the pressure-sensitive adhesive tape was evaluated as follows: when the amount of displacement was less than 0.5 mm, it was marked "◎"; when the amount of displacement was 0.5 mm or more but the test piece did not fall, it was marked "○"; when the test piece fell 3 hours or more but less than 24 hours after the start of the test, it was marked "△"; and when the test piece fell less than 3 hours after the start of the test, it was marked "×".

[0132] (Reworkability) A probe tack test was performed in accordance with JIS Z3284 to measure the probe tack value of the pressure-sensitive adhesive layer. Specifically, the obtained pressure-sensitive adhesive tape was cut into a size of 30 mm wide x 30 mm long to prepare a test piece, and then the pressure-sensitive adhesive layer of the prepared test piece was subjected to a probe tack test using a probe tack tester (manufactured by RHESCA, "TAC-2") under the conditions of 23 ° C, pressure of 98 gf, pressure rate of 100 mm / sec, pressure time of 3 seconds, and peel rate of 5 mm / sec, and the probe tack value (N / 5 mmφ) of the pressure-sensitive adhesive layer was measured. The initial reworkability of the pressure-sensitive adhesive tape was evaluated as follows: if the probe tack value of the obtained pressure-sensitive adhesive layer was 7.5 N / 5 mmφ or less, it was marked "○", if it was more than 7.5 N / 5 mmφ and less than 12.5 N / 5 mmφ, it was marked "△", and if it was more than 12.5 N / 5 mmφ, it was marked "X". Even when the evaluation is "x", the pressure-sensitive adhesive tape of the present invention can be handled without any practical problems depending on the application.

[0133] (Suitability for Fixing Adherend Having a Bent Portion) A flip-up test was conducted to evaluate the suitability of the pressure-sensitive adhesive tape for fixing an adherend having a bent portion. FIG. 4 is a diagram schematically illustrating the flip-up test. Specifically, a polycarbonate (PC) plate 1 (manufactured by Takiron C.I., "PC-1600") having a width of 50 mm, a length of 100 mm, and a thickness of 6 mm was bonded to a PET film 5 (manufactured by Toray Industries, Inc., "Lumirror #188") having a width of 10 mm, a length of 70 mm, and a thickness of 188 μm using double-sided tape (manufactured by Sekisui Chemical Co., Ltd., "Double Tack Tape #570E"), and then a 2 kg rubber roller was made to reciprocate once on the polycarbonate plate 1 at a speed of 300 mm / min to produce a laminate in which the polycarbonate plate 1 and the PET film 5 were integrated via the double-sided tape. The adhesive tape obtained in each of the Examples and Comparative Examples was cut into a size of 10 mm wide and 3 mm long to form adhesive tape 2, which was then bonded to polycarbonate plate 1 of the resulting laminate. The portion of PET film 5 in the laminate where polycarbonate plate 1 was not laminated was then bent and overlapped with adhesive tape 2 to prepare a measurement sample (see FIG. 4 ). The prepared measurement sample was placed in a constant humidity oven at 65°C and 90% RH for 72 hours to perform a flip-up test. The measurement sample was then removed from the oven, and the lift height H (mm) (see FIG. 5 ) between adhesive tape 2 and PET film 5 was measured with a vernier caliper. The suitability of the adhesive tape for fixing an adherend having a curved portion was evaluated as follows: "Good" if the lift height H was 1 mm or less; "Fair" if the lift height was greater than 1 mm but adhesive tape 2 did not peel; and "Poor" if adhesive tape 2 peeled. Even when the evaluation was "Poor," the adhesive tape of the present invention can be used practically without any problems depending on the application.

[0134]

[0135]

[0136]

[0137]

[0138]

[0139] According to the present invention, it is possible to provide a pressure-sensitive adhesive tape that has excellent heat resistance and excellent impact resistance against various types of impact.

[0140] 1 Polycarbonate (PC) plate 2 Adhesive tape 3 Perforated polycarbonate (PC) plate 4 SUS block 5 Polyethylene terephthalate (PET) film 6 SUS304 plate 7 Weight (1.5 kg)

Claims

1. Having an adhesive layer formed using an adhesive composition, The adhesive layer has a glass transition temperature of 0°C or higher, as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C. The adhesive layer has a peak width at half maximum of 38°C or higher, as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C. An adhesive tape characterized by the following features.

2. The adhesive layer has a shear storage modulus at 80°C of 2.0 × 10⁻¹⁶, as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C. ４ The adhesive tape according to claim 1, wherein the pressure is Pa or greater.

3. The adhesive layer has a shear storage modulus of 0.25 MPa or higher at 23°C. The adhesive layer has a loss tangent of 0.50 or more at 65°C. The adhesive tape according to claim 1 or 2.

4. The adhesive composition contains a (meth)acrylic copolymer, The (meth)acrylic copolymer has structural units derived from alkyl (meth)acrylate and structural units derived from monomers having crosslinkable functional groups. The adhesive tape according to claim 1 or 2, wherein the (meth)acrylic copolymer has a content of 0.01% by mass or more and 20% by mass or less of constituent units derived from the monomer having the crosslinkable functional group.

5. The alkyl (meth)acrylate includes an alkyl (meth)acrylate having an alkyl group with 7 to 10 carbon atoms. The (meth)acrylic copolymer contains 45% by mass or more of constituent units derived from alkyl (meth)acrylate having an alkyl group having 7 to 10 carbon atoms. The adhesive tape according to claim 4.

6. The alkyl (meth)acrylate includes an alkyl (meth)acrylate having a branched alkyl group, The (meth)acrylic copolymer contains 45% by mass or more of constituent units derived from the branched alkyl group alkyl (meth)acrylate. The adhesive tape according to claim 4.

7. The adhesive tape according to claim 4, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having a boiling point of 200°C or higher.

8. The adhesive tape according to claim 4, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate whose glass transition temperature when it is a homopolymer is -50°C or higher.

9. The adhesive tape according to claim 4, wherein the alkyl (meth)acrylate comprises 1-methylheptyl acrylate.

10. The adhesive tape according to claim 4, wherein the alkyl (meth)acrylate comprises n-heptyl (meth)acrylate.

11. The monomer having the crosslinkable functional group includes a monomer containing a hydroxyl group, The adhesive tape according to claim 4, wherein the (meth)acrylic copolymer has a content of 0.01% by mass or more and 2.0% by mass or less of constituent units derived from the hydroxyl group-containing monomer.

12. The monomer having the crosslinkable functional group includes a monomer containing a carboxyl group, The adhesive tape according to claim 4, wherein the (meth)acrylic copolymer has a content of 0.1% by mass or more and 15% by mass or less of constituent units derived from the carboxyl group-containing monomer.

13. The adhesive tape according to claim 4, wherein the (meth)acrylic copolymer has at least one constituent unit selected from the group consisting of constituent units derived from monomers having a cyclic ether structure other than epoxy and oxetane structures, and constituent units derived from monomers having an acyclic ether structure.

14. The adhesive tape according to claim 13, wherein the (meth)acrylic copolymer contains 0.01% by mass or more and 50% by mass or less constituent units derived from monomers having a cyclic ether structure other than the epoxy structure and the oxetane structure, and constituent units derived from monomers having the acyclic ether structure.

15. The adhesive tape according to claim 4, wherein the (meth)acrylic copolymer does not have a crosslinkable functional group and has constituent units derived from a monomer whose glass transition temperature is 0°C or higher when it is a homopolymer.

16. The adhesive tape according to claim 15, wherein the (meth)acrylic copolymer does not have the crosslinkable functional group and the content of constituent units derived from monomers having a glass transition temperature of 0°C or higher when homopolymerized is 0.1% by mass or more and 70% by mass or less.

17. The adhesive tape according to claim 4, wherein the (meth)acrylic copolymer has a weight-average molecular weight of 300,000 or more and 1,500,000 or less, and a polydispersity of 7.0 or less.

18. The aforementioned adhesive composition contains a tackifier, In the adhesive composition, the content of the tackifier per 100 parts by mass of the (meth)acrylic copolymer is 10 parts by mass or more and 50 parts by mass or less. The adhesive tape according to claim 4.

19. The adhesive tape according to claim 18, wherein the tackifier comprises a tackifier having a softening point of 80°C or more and 170°C or less.

20. The adhesive tape according to claim 18, wherein the tackifier comprises a tackifier having a hydroxyl value of 20 mg KOH / g or more and 150 mg KOH / g or less.

21. The adhesive tape according to claim 18, wherein the tackifier comprises at least one selected from the group consisting of rosin ester-based tackifiers, terpene-based tackifiers, and acrylic-based tackifiers.

22. The adhesive tape according to claim 21, comprising the rosin ester-based tackifier and the terpene-based tackifier.

23. The aforementioned adhesive composition contains a crosslinking agent, The adhesive tape according to claim 4, wherein the crosslinking agent comprises at least one selected from the group consisting of isocyanate-based crosslinking agents and epoxy-based crosslinking agents.

24. The adhesive tape according to claim 23, wherein the crosslinking agent comprises the isocyanate-based crosslinking agent and the epoxy-based crosslinking agent.

25. In the adhesive composition, the content of the crosslinking agent per 100 parts by mass of the (meth)acrylic copolymer is 0.01 parts by mass or more and 10 parts by mass or less. The adhesive tape according to claim 23.

26. The adhesive tape according to claim 1 or 2, wherein the gel fraction of the adhesive layer is 20% by mass or more and 70% by mass or less.

27. The adhesive tape according to claim 1 or 2, wherein the thickness of the adhesive layer is 5 μm or more.

28. The adhesive tape according to claim 1 or 2, wherein the height of the peak of the loss loss tangent measured by dynamic viscoelastic measurement at a measurement frequency of 1 Hz and a measurement temperature range of -40°C to 200°C is 1.50 or less.

29. It has a base layer and adhesive layers on both sides of the base layer. The adhesive tape according to claim 1 or 2, having the adhesive layer on at least one surface of the base material layer.

30. The adhesive tape according to claim 1 or 2, which does not have a base layer.