Double-sided adhesive tape equipped with separator

Abstract

The purpose of the present invention is to provide a double-sided adhesive tape equipped with a separator that makes it possible to suppress lifting of the separator from the adhesive tape when bonded to a curved surface. The present invention is a double-sided adhesive tape equipped with a separator including: a double-sided adhesive tape having an adhesive layer; and a separator on at least one surface of the double-sided adhesive tape, wherein when a dumbbell tensile test is performed at a tensile speed of 100 mm / min on a multilayer body including the separator on one surface of the double-sided adhesive tape, the multilayer body does not break when the length thereof is stretched by 2.0%, and the tensile strength is 17N or less when the length of the multilayer body is stretched by 2.0%.

Description

Double-sided adhesive tape with separator

[0001] The present invention relates to a separator-attached double-sided pressure-sensitive 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, electronic devices have become more functional and their designs more diverse. In particular, display devices have become bendable thanks to the use of organic light-emitting diodes (OLEDs), and there is a trend to enhance the design of devices by making them curved.

[0005] To bend and hold devices like OLEDs, it is necessary to prepare a curved module and attach it to the panel. Adhesive tape and adhesives are considered as attachment methods, but because bending the panel in three dimensions creates an immediate repulsive force upon bonding, adhesives that take time to develop adhesive strength are not suitable. Therefore, adhesive tape that can develop adhesive strength from the beginning is desirable. Furthermore, processing is possible even when the process of attaching the adhesive tape to the module and the panel bonding process are carried out at different locations.

[0006] When the process of attaching adhesive tape to a module and the process of attaching panels are performed at different locations, it is necessary to attach the adhesive tape to the module without the separator floating when it is attached to a three-dimensionally curved support. However, the separators laminated on conventional adhesive tapes are often laminated with PET or PE (such as wood-free paper), which are highly rigid and can repel and float when attached to a curved surface, resulting in a decrease in the adhesive strength of the exposed adhesive layer.

[0007] An object of the present invention is to provide a double-sided adhesive tape with a separator that can prevent the separator from lifting off the adhesive tape when the tape is attached to a curved surface.

[0008] Disclosure 1 is a separator-attached double-sided pressure-sensitive adhesive tape comprising a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer and a separator on at least one side of the double-sided pressure-sensitive adhesive tape, wherein, when a dumbbell tensile test is performed on a laminate having a separator on one side of the double-sided pressure-sensitive adhesive tape at a tensile speed of 100 mm / min, the laminate does not break when elongated by 2.0% in length and the tensile strength of the laminate when elongated by 2.0% is 17 N or less. Disclosure 2 is a separator-attached double-sided pressure-sensitive adhesive tape according to Disclosure 1, wherein, when a dumbbell tensile test is performed on the laminate at a tensile speed of 100 mm / min, the slope of the line at a displacement strain of 0.8 to 1.5% is 30 N / mm or less. Disclosure 3 is a separator-attached double-sided pressure-sensitive adhesive tape according to Disclosure 1 or 2, wherein the laminate has a hysteresis loss rate of 1.0% or more when elongated by 2.5% in length. Disclosure 4 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosure 1, 2, or 3, wherein the laminate has a tensile strength at break of 5.0 N or more when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min. Disclosure 5 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosure 1, 2, 3, or 4, wherein the laminate has a thickness of 150 μm or less. Disclosure 6 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, or 5, wherein the separator does not break when elongated by 2.0% in length when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, and the separator has a tensile strength of 17 N or less when elongated by 2.0% in length. Disclosure 7 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, or 6, wherein the separator has a tensile modulus of 5000 MPa or less at a displacement strain of 0.8 to 1.5% when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min. Disclosure 8 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, or 7, wherein the separator has a 180° peel strength from the pressure-sensitive adhesive layer of 0.05 N / 50 mm or more and 5.0 N / 50 mm or less. Disclosure 9 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, or 8, wherein the separator is a release-treated film and has a thickness of 100 μm or less.Disclosure 10 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the pressure-sensitive adhesive layer has a thickness of 5.0 μm or more. Disclosure 11 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the pressure-sensitive adhesive layer has a 180° peel strength from SUS at 23° C. of 10 N / 25 mm or more. Disclosure 12 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, wherein the pressure-sensitive adhesive layer has a glass transition temperature of -15° C. or more and 20° C. or less, as measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and in a measurement temperature range of -40° C. or more and 200° C. or less. In the present disclosure 13, the pressure-sensitive adhesive layer has a shear storage modulus of 5.0 × 10 at 25°C measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and a measurement temperature range of −40°C or higher and 200°C or lower. ４ Pa or more 50×10 ４

[0023] The separator-equipped double-sided pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, having a viscosity of 100 Pa or less. Disclosure 14 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, wherein the pressure-sensitive adhesive layer is formed using a pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive composition, the acrylic pressure-sensitive adhesive composition contains a (meth)acrylic copolymer having a structural unit derived from an alkyl(meth)acrylate and a structural unit derived from a monomer having a crosslinkable functional group, and the pressure-sensitive adhesive layer has a gel fraction of 70 mass% or less. Disclosure 15 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosure 14, wherein the alkyl(meth)acrylate contains an alkyl(meth)acrylate having an alkyl group having 4 to 8 carbon atoms, and the (meth)acrylic copolymer contains 50 mass% or more of structural units derived from an alkyl(meth)acrylate having an alkyl group having 4 to 8 carbon atoms. Disclosure 16 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosure 15, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms, and the (meth)acrylic copolymer contains 50 mass% or more of structural units derived from an alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms. Disclosure 17 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosure 16, wherein the (meth)acrylic copolymer contains two or more types of structural units derived from an alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms, and the total content of the structural units derived from an alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms is 50 mass% or more. Disclosure 18 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosure 14, 15, 16, or 17, wherein the alkyl (meth)acrylate includes an alkyl (meth)acrylate having a linear alkyl group, and the (meth)acrylic copolymer contains 50 mass% or more of structural units derived from the alkyl (meth)acrylate having a linear alkyl group.Disclosure 19 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, or 18, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having a boiling point of 250° C. or lower. Disclosure 20 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, or 19, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having a glass transition temperature of −50° C. or lower when made into a homopolymer. Disclosure 21 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, 19, or 20, wherein the alkyl (meth)acrylate comprises a biologically derived material.

[0022] Disclosure 22 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, 19, 20, or 21, wherein the (meth)acrylic copolymer contains structural units derived from the monomer having a crosslinkable functional group in an amount of 0.01% by mass or more and 20% by mass or less. Disclosure 23 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, 19, 20, 21, or 22, wherein the monomer having a crosslinkable functional group includes a hydroxyl group-containing monomer, and the (meth)acrylic copolymer contains structural units derived from the hydroxyl group-containing monomer in an amount of 0.01% by mass or more and 2.0% by mass or less.

[0023] Disclosure 24 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23, wherein the monomer having a crosslinkable functional group includes a carboxy group-containing monomer, and the (meth)acrylic copolymer has a content of structural units derived from the carboxy group-containing monomer of 0.1% by mass or more and 15% by mass or less. Disclosure 25 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24, 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. Disclosure 26 is the separator-equipped double-sided 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 composition contains a tackifier resin, and the tackifier resin includes a tackifier resin having a softening point of 80°C or higher and 170°C or lower.

[0023] Disclosure 27 is the separator-attached double-sided 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 26, wherein the PSA composition contains a tackifier resin, and the tackifier resin comprises a tackifier resin having a hydroxyl value of 20 mgKOH / g or more and 150 mgKOH / g or less. Disclosure 28 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, or 27, wherein the PSA composition contains a tackifier resin, and the content of the tackifier resin in the PSA 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.

[0033] Disclosure 29 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosures 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, or 28, 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 30 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosure 29, wherein in the pressure-sensitive 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. Disclosure 31 is the separator-equipped double-sided 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, 28, 29, or 30, wherein the double-sided pressure-sensitive adhesive tape has a base layer, and the thickness of the base layer is 100 μm or less. Disclosure 32 is the separator-equipped double-sided 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, 28, 29, or 30, wherein the double-sided pressure-sensitive adhesive tape does not have a base layer. Disclosure 33 is the separator-equipped double-sided pressure-sensitive adhesive tape of Disclosure 31, wherein, when the base material layer is subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, the base material layer does not break when the length of the base material layer elongates by 2.0%, and the tensile strength of the base material layer when the length of the base material layer elongates by 2.0% is 17 N or less.

[0033] Disclosure 34 is the separator-attached double-sided pressure-sensitive adhesive tape of Disclosure 31 or 33, wherein the base material layer has a tensile modulus of 5000 MPa or less at a displacement strain of 0.8 to 1.5% when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min. Disclosure 35 is the separator-attached double-sided 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, 28, 29, 30, 31, 32, 33, or 34, wherein the separator is a resin film, and the resin in the resin film is polyethylene terephthalate resin, polypropylene resin, polyethylene resin, or polybutylene terephthalate resin. Hereinafter, embodiments of the present invention will be described in detail.

[0009] The present inventors conducted a dumbbell tensile test under specific conditions using a laminate having a separator on one side of the double-sided adhesive tape, which had a double-sided adhesive tape and a separator. As a result, they found that when the laminate did not break when stretched 2.0% in length and the tensile strength when stretched 2.0% in length was within a specific range, it was possible to obtain a double-sided adhesive tape with a separator that had excellent adhesion to curved surfaces and was able to prevent the separator from lifting off the adhesive tape when stretched to a curved surface, and they were able to complete the present invention.

[0010] A separator-equipped double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention comprises a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer and a separator on at least one side of the double-sided pressure-sensitive adhesive tape. That is, the separator-equipped double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention may have a separator on one side or on both sides.

[0011] In a separator-equipped double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention, when a laminate (hereinafter sometimes simply referred to as "laminate") having a separator on one side of the double-sided pressure-sensitive adhesive tape is subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, the laminate does not break when elongated by 2.0% in length, and the upper limit of the tensile strength when the laminate elongates by 2.0% in length (hereinafter sometimes simply referred to as "tensile strength of the laminate") is 17 N. Having a tensile strength of 17 N or less for the separator-equipped double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention allows the tape to be easily stretched to conform to a curved surface and bonded to the tape, thereby preventing the separator from lifting off the tape when bonded. Furthermore, having a tensile strength of 17 N or less for the separator-equipped double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention makes it easier to prevent the separator from lifting off the tape even long after bonding. The upper limit of the tensile strength of the laminate is preferably 15 N, more preferably 12 N, even more preferably 10 N, and even more preferably 8.4 N. The lower limit of the tensile strength of the laminate is preferably 1.0 N. When the tensile strength of the laminate is 1.0 N or more, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be prevented from unintentionally stretching, making it easier to attach to curved surfaces. The lower limit of the tensile strength of the laminate is more preferably 2.0 N, and even more preferably 3.0 N. In this specification, the term "laminate" refers to a structure in which a separator is laminated on only one side of the double-sided pressure-sensitive adhesive tape. When the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention has separators on both sides, the laminate used is one in which the separator on the side not being measured has been peeled off from the double-sided pressure-sensitive adhesive tape. Furthermore, when the separator-attached double-sided adhesive tape of one embodiment of the present invention has separators on both sides, it is sufficient that the tensile strength of the laminate satisfy the above range with the laminate having one of the separators, and from the viewpoint of handleability of the separator-attached double-sided adhesive tape of one embodiment of the present invention, it is preferable that the tensile strength of the laminate satisfy the above range with only the laminate having one of the separators.The same applies to the parameters relating to the laminate described below.

[0012] The tensile strength of the laminate when the length is elongated by 2.0% can be controlled by adjusting the material (resin constituting the separator, etc.) and thickness of the separator.

[0013] When the laminate is subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, the slope of the line at a displacement strain of 0.8 to 1.5% (hereinafter sometimes simply referred to as the "slope in the dumbbell tensile test of the laminate") is preferably 30 N / mm at its upper limit. When the slope in the dumbbell tensile test of the laminate is 30 N / mm or less, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention becomes more flexible, and the generation of wrinkles when it is attached to a curved surface can be suppressed. The upper limit of the slope in the dumbbell tensile test of the laminate is more preferably 25 N / mm, even more preferably 20 N / mm, and even more preferably 15.5 N / mm. Furthermore, the lower limit of the slope in the dumbbell tensile test of the laminate is preferably 1.0 N / mm. When the slope in the dumbbell tensile test of the laminate is 1.0 N / mm or more, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more effectively prevented from stretching too much when it is attached to a curved surface, and the adhesive performance can be better maintained. A more preferable lower limit of the slope in the dumbbell tensile test of the laminate is 2.0 N / mm.

[0014] The inclination of the laminate in a dumbbell tensile test can be controlled by adjusting the materials of the separator and base layer (such as the resins constituting the separator and base layer) and the thickness of the separator and base layer.

[0015] When the laminate is subjected to a dumbbell tensile test at a tension speed of 100 mm / min, the preferred lower limit of the tensile breaking strength (hereinafter sometimes simply referred to as "tensile breaking strength of the laminate") is 5.0 N. When the tensile breaking strength of the laminate is 5.0 N or more, it is possible to further prevent the adhesive layer from stretching too much and causing thickness variations when the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention is adhered to a curved surface. A more preferred lower limit of the tensile breaking strength of the laminate is 10 N, and an even more preferred lower limit is 15 N. Furthermore, a preferred upper limit of the tensile breaking strength of the laminate is 70 N, and an even more preferred upper limit is 40 N.

[0016] The tensile breaking strength of the laminate can be controlled by adjusting the materials of the separator and the substrate layer (such as the resins constituting the separator and the substrate layer) and the thickness of the separator and the substrate layer.

[0017] When the laminate is subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, the tensile elongation at break (hereinafter sometimes simply referred to as "tensile elongation at break of the laminate") preferably has a lower limit of 20 mm and an upper limit of 400 mm. When the tensile elongation at break of the laminate is 20 mm or more, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more easily conformed to a curved surface and attached to the surface without breaking the separator or the double-sided pressure-sensitive adhesive tape. When the tensile elongation at break of the laminate is 400 mm or less, the separator or the double-sided pressure-sensitive adhesive tape does not become too flexible, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention has excellent handleability and is easier to attach to the surface. The tensile elongation at break of the laminate is more preferably 22 mm at the lower limit, more preferably 370 mm at the upper limit, even more preferably 25 mm at the lower limit, even more preferably 350 mm at the upper limit, still more preferably 27 mm at the lower limit, even more preferably 330 mm at the upper limit, particularly preferably 30 mm at the lower limit, particularly preferably 300 mm at the upper limit, especially preferably 40 mm at the lower limit, especially preferably 270 mm at the upper limit, still more especially preferably 45 mm at the lower limit, even more especially preferably 250 mm at the upper limit, very preferably 50 mm at the lower limit, and very preferably 200 mm at the upper limit.

[0018] The tensile elongation at break of the laminate can be controlled by adjusting the materials of the separator and the substrate layer (such as the resins constituting the separator and the substrate layer) and the thickness of the separator and the substrate layer.

[0019] When the laminate is subjected to a dumbbell tensile test at a tension speed of 100 mm / min, the tensile elongation at break (hereinafter sometimes simply referred to as "tensile elongation at break of the laminate") preferably has a lower limit of 200% and an upper limit of 1100%. When the tensile elongation at break of the laminate is 200% or more, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more easily conformed to a curved surface and bonded to it without breaking the separator or the double-sided pressure-sensitive adhesive tape. When the tensile elongation at break of the laminate is 1100% or less, the separator or the double-sided pressure-sensitive adhesive tape does not become too flexible, resulting in excellent handleability of the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention and easier bonding. The tensile elongation at break of the laminate is more preferably 225% lower, more preferably 975%, even more preferably 250%, even more preferably 900%, even more preferably 350%, and even more preferably 850%.

[0020] When the laminate is subjected to a dumbbell tensile test at a tension speed of 100 mm / min, the tensile modulus at a displacement strain of 0.8 to 1.5% (hereinafter sometimes simply referred to as the "tensile modulus of the laminate") preferably has a lower limit of 1.0 MPa and an upper limit of 5000 MPa. When the tensile modulus of the laminate is 1.0 MPa or more, excessive stretching of the adhesive layer can be more effectively prevented when the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention is adhered to a curved surface, resulting in superior adhesive strength to the curved surface of the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention. When the tensile modulus of the laminate is 5000 MPa or less, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention becomes more flexible, thereby preventing wrinkling when adhered to a curved surface. The tensile modulus of the laminate is more preferably 5.0 MPa lower, more preferably 3000 MPa upper, even more preferably 10 MPa lower, and even more preferably 2000 MPa upper.

[0021] The tensile modulus of the laminate can be controlled by adjusting the separator material (such as the resin constituting the separator), the type of substrate, the composition of the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer, and the like.

[0022] In this specification, the dumbbell tensile test is performed in accordance with JIS K 7161 by the following method. Specifically, for example, a test piece is prepared by punching a dumbbell-shaped specimen from the object to be measured (a laminate, a separator, or a substrate layer) using a punching blade (e.g., a "Tensile No. 3 Dumbbell" manufactured by Kobunshi Keiki Co., Ltd.). The obtained test piece is subjected to a dumbbell tensile test using a tensile tester (e.g., an "Autograph AGS-X" manufactured by Shimadzu Corporation) or the like, with the distance between the grippers set to 40 mm, and the test piece is pulled at a tensile speed of 100 mm / min until it breaks. Note that when punching out a dumbbell-shaped test piece from the object to be measured (a laminate, a separator, or a substrate layer), the longitudinal direction of the object to be measured (a laminate, a separator, or a substrate layer) is usually assumed to coincide with the tensile direction in the tensile test. In the dumbbell tensile test, the stress measured when the test piece is elongated by 2.0% is defined as the tensile strength (N), and the displacement from the initial grip distance at the start of the dumbbell tensile test to the grip distance at which the test piece breaks is defined as the tensile elongation at break (mm). The slope of the line (N / mm) at displacement strains of 0.8 to 1.5% was calculated from two points on the S-S curve obtained from the dumbbell tensile test: the point at a displacement strain of 0.8% and the point at a displacement strain of 1.5%. The tensile break strength (N) was calculated from the break strength per unit area at which the test piece broke. The tensile modulus (MPa) was calculated from the displacement strain of 0.8 to 1.5% using the S-S curve obtained from the dumbbell tensile test. Furthermore, the tensile break elongation (%) was calculated using the following formula (I): Tensile elongation at break (%) = (distance between grippers at break / initial distance between grippers) × 100 (I)

[0023] In a preferred embodiment of the present invention, when dumbbell-shaped test pieces are punched out from the object to be measured (laminate, separator, base layer), not only test pieces in which the tensile direction in the tensile test is the longitudinal direction of the object to be measured (laminate, separator, base layer) but also test pieces in which the tensile direction in the tensile test is a direction perpendicular to the longitudinal direction of the object to be measured (laminate, separator, base layer) may be prepared and measured. In this case, from the viewpoint of functional expression in two dimensions, it is more preferable that the above-mentioned and below-described parameters measured by performing a dumbbell tensile test also satisfy the above-mentioned and below-described ranges for test pieces in which the tensile direction in the tensile test is a direction perpendicular to the longitudinal direction.

[0024] The preferred lower limit of the hysteresis loss rate of the laminate when stretched 2.5% in length (hereinafter sometimes simply referred to as "the hysteresis loss rate of the laminate") is 1.0%. When the hysteresis loss rate of the laminate is 1.0% or more, the stress acting in the restoration direction when the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention is stretched and attached to a curved surface is reduced, thereby more effectively preventing the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention from lifting after being attached to the curved surface. A more preferred lower limit of the hysteresis loss rate of the laminate is 5.0%, and an even more preferred lower limit is 10%. Furthermore, a preferred upper limit of the hysteresis loss rate of the laminate is 60%. When the hysteresis loss rate of the laminate is 60% or less, an appropriate stress is applied to the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention, making it easier to attach it to a curved surface. The upper limit of the hysteresis loss rate of the laminate is more preferably 50%, even more preferably 40%, and even more preferably 30%. Specific examples of hysteresis loss rates of the laminate that satisfy these upper limits include 25% or less. The hysteresis loss rate of the laminate is measured in accordance with JIS K 6400-2 by the following method. Specifically, for example, a dumbbell-shaped test piece is prepared by punching the laminate using a punching blade (e.g., a "Tensile No. 3 Dumbbell" manufactured by Kobunshi Keiki Co., Ltd.). In a preferred embodiment of the present invention, when punching a dumbbell-shaped test piece from the object to be measured (the laminate, separator, or base layer), the longitudinal direction of the pressure-sensitive adhesive tape usually coincides with the tensile direction in the tensile test. The obtained test piece is subjected to a tensile test using a tensile tester (for example, Shimadzu Corporation's "Autograph AGS-X"), with the distance between the grippers set to 40 mm, and the test piece is pulled 1 mm at a tensile speed of 100 mm / min, held in this state for 1 second, and then released at the same speed. The hysteresis loss rate (%) is then calculated using the obtained force-deflection curve.

[0025] In a preferred embodiment of the present invention, when dumbbell-shaped test pieces are punched out from the object to be measured (laminate, separator, base layer), not only test pieces in which the longitudinal direction of the object to be measured (laminate, separator, base layer) is the tensile direction in the tensile test, but also test pieces in which the tensile direction in the direction perpendicular to the longitudinal direction of the object to be measured (laminate, separator, base layer) may be prepared and measured. In this case, from the viewpoint of functional expression in two-dimensional directions, it is more preferable that the hysteresis loss rate of the above-mentioned laminate also satisfies the above-mentioned range for test pieces in which the tensile direction in the tensile test is the direction perpendicular to the longitudinal direction.

[0026] The hysteresis loss rate of the laminate can be controlled by adjusting the separator material (such as the resin constituting the separator), the type of the base layer, the composition of the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer, and the like.

[0027] The preferred upper limit of the thickness of the laminate is 150 μm. When the thickness of the laminate is 150 μm or less, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention becomes more flexible, thereby making it possible to more effectively prevent wrinkles from forming when the tape is attached to a curved surface. The preferred upper limit of the thickness of the laminate is 120 μm, and even more preferably 100 μm. Furthermore, from the viewpoints of the yield of the attachment operation and the expression of adhesive properties, the preferred lower limit of the thickness of the laminate is 20 μm, and even more preferably 50 μm.

[0028] In the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention, the separator may be, for example, paper, a resin film, etc. Among these, a resin film is preferred from the viewpoint of ease of adjusting the thickness.

[0029] Examples of the resin in the resin film include polyethylene terephthalate (PET) resin, polypropylene (PP) resin, polyethylene (PE) resin, polybutylene terephthalate (PBT) resin, etc. Among these, polyethylene (PE) resin and polybutylene terephthalate (PBT) resin are preferred from the viewpoint of making the resulting resin film more flexible.

[0030] Examples of the paper include fine paper, kraft paper, glassine paper, etc. The paper may be laminated with polyethylene (PE).

[0031] From the viewpoint of facilitating peeling of the separator from the pressure-sensitive adhesive layer without damaging the shape of the pressure-sensitive adhesive layer, the separator is preferably a release-treated film. Examples of the release-treated film include the resin film having at least one surface thereof subjected to release treatment.

[0032] The surface of the separator may be coated with silicon (Si coating). Examples of methods for coating the surface of the separator with Si include coating by heat curing and coating by ultraviolet irradiation. Heat-resistant paper, PET film, and stretched PP film can be Si-coated by heat curing to improve the adhesion of the Si coating to the separator.

[0033] The separator may have an embossed surface. When the separator has an embossed surface, grooves can be formed in the pressure-sensitive adhesive layer, which improves air release properties when the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention is attached, resulting in superior removability.

[0034] The separator preferably has a thickness of 100 μm or less. When the separator has a thickness of 100 μm or less, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention becomes more flexible, thereby more effectively preventing wrinkles from forming when the tape is attached to a curved surface. The separator's thickness is more preferably 75 μm or less, and even more preferably 50 μm or less. From the viewpoint of the yield of the attachment operation, the separator's thickness is preferably 10 μm or less, and even more preferably 20 μm or less. When the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention has separators on both sides, it is more preferable that the thickness of the separator on both sides satisfies the above range. The same applies to the separator-related parameters described below.

[0035] When the separator is subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, the separator does not break when elongated by 2.0% in length, and the tensile strength when the separator elongates by 2.0% in length (hereinafter sometimes simply referred to as "separator tensile strength") is preferably 17 N. When the separator has a tensile strength of 17 N or less, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be more easily stretched to conform to a curved surface and adhered to it. A more preferred upper limit of the tensile strength of the separator is 15 N, and an even more preferred upper limit is 12 N. Furthermore, a preferred lower limit of the tensile strength of the separator is 1.0 N. When the separator has a tensile strength of 1.0 N or more, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be more easily prevented from being unintentionally stretched, and therefore can be more easily adhered to a curved surface. A more preferred lower limit of the tensile strength of the separator is 2.0N, and an even more preferred lower limit is 3.0N.

[0036] The tensile strength of the separator can be controlled by adjusting the material (such as the resin constituting the separator) and thickness of the separator.

[0037] When a dumbbell tensile test is performed on the separator at a tension speed of 100 mm / min, the preferred upper limit of the tensile modulus at a displacement strain of 0.8 to 1.5% (hereinafter sometimes simply referred to as the "tensile modulus of the separator") is 5000 MPa. When the tensile modulus of the separator is 5000 MPa or less, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention becomes more flexible, thereby more effectively preventing wrinkles from forming when the tape is attached to a curved surface. A more preferred upper limit of the tensile modulus of the separator is 3000 MPa, and an even more preferred upper limit is 2000 MPa. Furthermore, a preferred lower limit of the tensile modulus of the separator is 1.0 MPa. When the tensile modulus of the separator is 1.0 MPa or more, excessive stretching of the pressure-sensitive adhesive layer can be prevented when the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention is attached to a curved surface, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention exhibits excellent adhesive strength to curved surfaces. The lower limit of the tensile modulus of the separator is more preferably 5.0 MPa, and even more preferably 10 MPa.

[0038] The tensile modulus of the separator can be controlled by adjusting the material of the separator (such as the resin constituting the separator).

[0039] When the separator is subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, the tensile elongation at break (hereinafter sometimes simply referred to as "separator tensile elongation at break") preferably has a lower limit of 40 mm and a preferred upper limit of 400 mm. When the separator has a tensile elongation at break of 40 mm or more, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be more easily conformed to curved surfaces and bonded to them without breaking the separator. When the separator has a tensile elongation at break of 400 mm or less, the separator does not become too flexible, and the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention has better handleability and is easier to bond to other surfaces. The separator's tensile elongation at break is more preferably 50 mm lower, more preferably 350 mm upper, even more preferably 100 mm lower, and even more preferably 300 mm upper limit.

[0040] The tensile elongation at break of the separator can be controlled by adjusting the material of the separator (such as the resin constituting the separator).

[0041] The 180° peel strength of the separator from the pressure-sensitive adhesive layer is preferably 0.05 N / 50 mm at its lower limit and 5.0 N / 50 mm at its upper limit. Having a 180° peel strength of the separator from the pressure-sensitive adhesive layer of 0.05 N / 50 mm or more can further prevent the separator from lifting off the pressure-sensitive adhesive layer after the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention is bonded. Having a 180° peel strength of the separator from the pressure-sensitive adhesive layer of 5.0 N / 50 mm or less can further prevent the pressure-sensitive adhesive layer from breaking when the separator is peeled off. The 180° peel strength of the separator from the pressure-sensitive adhesive layer is more preferably 0.10 N / 50 mm at its lower limit and 1.5 N / 50 mm at its upper limit, and even more preferably 0.20 N / 50 mm at its lower limit and 1.0 N / 50 mm at its upper limit. The 180° peel strength of the separator from the pressure-sensitive adhesive layer is measured by the following method. Specifically, the obtained pressure-sensitive adhesive tape is first cut into a size of 50 mm wide x 100 mm long, and the separator is peeled from one side (the side not being measured). The exposed pressure-sensitive adhesive layer is backed with a 50 μm-thick PET film (manufactured by Toyobo Co., Ltd., "E5200#50") to prepare a test specimen. The SUS plate and the prepared test specimen are allowed to stand for 5 minutes in an environment of 23°C. Then, the prepared test specimen is subjected to a peel test in accordance with JIS Z 0237:2009 using a tensile tester (manufactured by Shimadzu Corporation, "Autograph AGS-X" or the like) at 23°C and a peel rate of 300 mm / min, in which the separator is peeled from the pressure-sensitive adhesive layer in a 180° direction. The peel strength can be measured.

[0042] The 180° peel strength of the separator from the pressure-sensitive adhesive layer can be controlled by adjusting the type of release agent in the separator and the surface roughness of the separator.

[0043] In a separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention, the double-sided pressure-sensitive adhesive tape has a pressure-sensitive adhesive layer. 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") measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz and within a measurement temperature range of -40°C to 200°C. The pressure-sensitive adhesive layer preferably has a lower limit of -15°C and an upper limit of 20°C. Having a glass transition temperature of -15°C or higher improves the repulsion resistance of the pressure-sensitive adhesive layer, and the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can more effectively prevent the separator from lifting after being applied to a curved surface. Furthermore, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be more easily re-applied to a curved surface or its position adjusted. Having a glass transition temperature of 20°C or lower improves the stress relaxation property of the pressure-sensitive adhesive layer, and the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can more effectively prevent the separator from lifting after being applied to a curved surface. The glass transition temperature of the pressure-sensitive adhesive layer is more preferably −10° C. in lower limit, more preferably 10° C. in upper limit, still more preferably −8.0° C. in lower limit, and still more preferably 5.0° C. in upper limit. In this specification, the “glass transition temperature” refers to the temperature at which a maximum due to micro-Brownian motion appears among the maximum loss tangents (tan δ) obtained by dynamic viscoelasticity measurement. In addition, when there are multiple maximum loss tangents, in this specification, the “glass transition temperature” refers to the temperature at which the maximum loss tangent appears at the lowest temperature among the maximum loss tangents in the temperature range of −25° C. or higher and 50° C. or lower.

[0044] Specific methods for adjusting the glass transition temperature of the pressure-sensitive adhesive layer include, for example, a method of using alkyl (meth)acrylate (a) described below as a constituent monomer of the (meth)acrylic copolymer described below and adjusting the content ratio thereof; a method of adjusting the content of a tackifier resin; a method of using a tackifier resin having a softening point within a specific range as a tackifier resin; and a method of adjusting the content of a crosslinking agent or the content ratio of a monomer having a crosslinkable functional group, and the gel fraction of the pressure-sensitive adhesive layer accordingly.

[0045] The pressure-sensitive adhesive layer has a shear storage modulus at 25°C (hereinafter, sometimes simply referred to as "the shear storage modulus of the pressure-sensitive adhesive layer at 25°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 5.0 x 10 ４ Pa, and the preferred upper limit is 50×10 ４ The pressure-sensitive adhesive layer has a shear storage modulus of 5.0 × 10 at 25°C. ４ By having a shear storage modulus of 50×10 Pa or more, the pressure-sensitive adhesive layer has improved repulsion resistance, and the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can further suppress lifting of the separator after being attached to a curved surface. Furthermore, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be more easily reattached to a curved surface or its position adjusted. The pressure-sensitive adhesive layer has a shear storage modulus of 50×10 Pa or more at 25° C. ４ When the shear storage modulus at 25°C of the pressure-sensitive adhesive layer is 6.0 x 10 Pa or less, the stress relaxation property of the pressure-sensitive adhesive layer is further improved, and the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can further suppress lifting of the separator after being attached to a curved surface. ４ Pa, and a more preferable upper limit is 30×10 ４ Pa, and a more preferable lower limit is 7.0 × 10 ４ Pa, and a more preferable upper limit is 20×10 ４ It is Pa.

[0046] The pressure-sensitive adhesive layer has a shear storage modulus at 0°C (hereinafter, sometimes simply referred to as "the shear storage modulus at 0°C 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, and the preferred lower limit is 30 x 10 ４ Pa, and the preferred upper limit is 200×10 ４ The shear storage modulus of the pressure-sensitive adhesive layer at 0°C is 30×10 ４ When the shear storage modulus of the pressure-sensitive adhesive layer at 0°C is 200 x 10 Pa or more, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention has excellent impact resistance even in a low-temperature environment. ４By setting the shear storage modulus at 0°C to 50 x 10 Pa or less, the pressure-sensitive adhesive layer can maintain its flexibility even in a low-temperature environment, and therefore the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention has excellent stress relaxation properties even in a low-temperature environment. ４ Pa, and a more preferable upper limit is 150×10 ４ Pa, and a more preferable lower limit is 70×10 ４ Pa, and a more preferable upper limit is 120×10 ４ It is Pa.

[0047] The pressure-sensitive adhesive layer has a shear storage modulus at 85°C (hereinafter, sometimes simply referred to as "the shear storage modulus of the pressure-sensitive adhesive layer at 85°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 1.0 x 10 ４ Pa, and the preferred upper limit is 10×10 ４ The shear storage modulus of the pressure-sensitive adhesive layer at 85°C is 1.0 × 10 ４ When the shear storage modulus of the pressure-sensitive adhesive layer is 10×10 Pa or more, the heat resistance of the pressure-sensitive adhesive layer is further improved, and the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be further prevented from peeling off in a high-temperature environment. ４ By setting the shear storage modulus at 85°C to 1.5 x 10 Pa or less, the pressure-sensitive adhesive layer does not become too hard, and the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention has excellent adhesion at room temperature. ４ Pa, and a more preferable upper limit is 7.0 × 10 ４ Pa, and a more preferable lower limit is 2.0 × 10 ４ Pa, and a more preferable upper limit is 5.0 × 10 ４ It is Pa.

[0048] Specific methods for adjusting the shear storage modulus of the pressure-sensitive adhesive layer include, for example, a method of using the alkyl(meth)acrylate (a) described below as a constituent monomer of the (meth)acrylic copolymer described below and adjusting its content ratio, a method of adjusting the content of a tackifier resin, a method of using a tackifier resin having a softening point within a specific range as a tackifier resin, and a method of adjusting the content of a crosslinking agent or the content ratio of a monomer having a crosslinkable functional group, and the gel fraction of the pressure-sensitive adhesive layer accordingly.

[0049] The glass transition temperature and shear storage modulus of the pressure-sensitive adhesive layer are measured by dynamic viscoelasticity measurement at a measurement frequency of 1 Hz. Specifically, first, the pressure-sensitive adhesive layers 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 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.).

[0050] The pressure-sensitive adhesive layer generally has a tensile strength at break of about 0.2 MPa to 2.0 MPa when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min.

[0051] The pressure-sensitive adhesive layer generally has a tensile modulus of elasticity of about 0.01 MPa to 0.5 MPa when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min.

[0052] The pressure-sensitive adhesive layer preferably has a lower thickness limit of 5.0 μm. When the thickness of the pressure-sensitive adhesive layer is 5.0 μm or more, the pressure-sensitive adhesive layer has improved repulsion resistance, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can further suppress lifting of the separator after being attached to a curved surface. The pressure-sensitive adhesive layer more preferably has a lower thickness limit of 10 μm, and even more preferably has a lower limit of 20 μm. Furthermore, from the viewpoint that if the thickness of the pressure-sensitive adhesive layer is too high, the flexibility of the pressure-sensitive adhesive layer is impaired and wrinkles are likely to occur after the pressure-sensitive adhesive tape is attached to a curved surface, the pressure-sensitive adhesive layer preferably has an upper thickness limit of 150 μm, and more preferably has an upper thickness limit of 100 μm.

[0053] The preferred lower limit of the 180° peel strength of the pressure-sensitive adhesive layer from SUS at 23°C (hereinafter sometimes simply referred to as "the 180° peel strength of the pressure-sensitive adhesive layer at 23°C") is 10 N / 25 mm. When the 180° peel strength of the pressure-sensitive adhesive layer at 23°C is 10 N / 25 mm or more, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can suppress separator lift-off after being attached to a curved surface. The preferred lower limit of the 180° peel strength of the pressure-sensitive adhesive layer at 23°C is 15 N / 25 mm, and even more preferred is 20 N / 25 mm. The preferred upper limit of the 180° peel strength of the pressure-sensitive adhesive layer at 23°C is 50 N / 25 mm, more preferably 40 N / 25 mm, and even more preferably 30 N / 25 mm. The 180° peel strength at 23°C of the pressure-sensitive adhesive layer refers to the 180° peel strength at 23°C of the pressure-sensitive adhesive layer located opposite the separator side, in the laminate used in a dumbbell tensile test or the like, where the tensile strength of the laminate is 17 N or less. The 180° peel strength at 23°C of the pressure-sensitive adhesive layer is measured by the following method. That is, first, the separator-attached double-sided pressure-sensitive adhesive tape is cut to a size of 25 mm wide x 100 mm long, and then the separator and release film on one side (the side not to be measured) are peeled off, and the exposed pressure-sensitive adhesive layer is backed with a 50 μm-thick PET film (manufactured by Toyobo Co., Ltd., "E5200#50") to prepare a test specimen. A test piece is pressure-bonded to a SUS plate (a SUS304 plate that has been washed with alcohol and then wiped dry) by rolling a 2 kg rubber roller back and forth once at a speed of 10 mm / s in an environment of 23° C., and then allowed to stand for 5 minutes in an environment of 23° C. to prepare a measurement sample. Then, the obtained measurement sample can be subjected to a peel test in accordance with JIS Z 0237:2009 using a tensile tester (Shimadzu Corporation, "Autograph AGS-X" or the like) at 23° C. and a peel rate of 300 mm / min, in which the adhesive tape is peeled off from the SUS plate in a direction of 180°, thereby allowing measurement.

[0054] Specific methods for adjusting the 180° peel strength at 23° C. of the pressure-sensitive adhesive layer include, for example, methods for adjusting the composition constituting the pressure-sensitive adhesive, the thickness, hardness, and interfacial interaction of the pressure-sensitive adhesive layer, and the like.

[0055] When the pressure-sensitive adhesive layer is formed from the acrylic pressure-sensitive adhesive composition described below, the preferred upper limit of the gel fraction of the pressure-sensitive adhesive layer is 70% by mass. A gel fraction of 70% by mass or less of the pressure-sensitive adhesive layer further improves the stress relaxation properties of the pressure-sensitive adhesive layer, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can further suppress separator lift-off after being attached to a curved surface. A more preferred upper limit of the gel fraction of the pressure-sensitive adhesive layer is 60% by mass, and an even more preferred upper limit is 50% by mass. A preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 5% by mass. A gel fraction of 5% by mass or more of the pressure-sensitive adhesive layer further improves the repulsion resistance of the pressure-sensitive adhesive layer, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can further suppress separator lift-off after being attached to a curved surface. A more preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 10% by mass, and an even more preferred lower limit is 20% by mass. The gel fraction of the pressure-sensitive adhesive layer is measured by the following method, etc. That is, first, a separator-attached double-sided adhesive tape having the above-mentioned adhesive layer is cut into a flat rectangular shape of 20 mm wide and 40 mm long to prepare a test piece, which is then immersed in ethyl acetate at 23°C for 24 hours, 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 (II). Note that no separator for protecting the above-mentioned adhesive layer is laminated on the test piece. Furthermore, when the adhesive tape of one embodiment of the present invention is a non-support type tape that does not have a substrate layer, the measurement is carried out using a test piece obtained by adhering to a substrate and cutting the tape, or the measurement is carried out using a test piece obtained by adhering to a substrate and cutting the tape 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 ) (II) (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)

[0056] Specific methods for adjusting the gel fraction of the pressure-sensitive adhesive layer include, for example, a method of adjusting the type or content ratio of a monomer having a crosslinkable functional group, as described below, and a method of adjusting the type or added number of parts of a crosslinking agent.

[0057] Examples of the pressure-sensitive adhesive layer include a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition or a pressure-sensitive adhesive. Examples of the pressure-sensitive adhesive composition or pressure-sensitive adhesive include an acrylic pressure-sensitive adhesive composition, a silicone-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, etc. Among these, a pressure-sensitive adhesive layer formed from an acrylic pressure-sensitive adhesive composition is preferred from the viewpoint of more easily improving the flexibility of the resulting pressure-sensitive adhesive layer.

[0058] The acrylic pressure-sensitive adhesive composition preferably contains a (meth)acrylic copolymer having a structural unit derived from an alkyl(meth)acrylate and a structural unit derived from a monomer having a crosslinkable functional group. In this specification, the term "(meth)acrylic" means acrylic or methacrylic, and the term "(meth)acrylate" means acrylate or methacrylate.

[0059] The alkyl (meth)acrylate in the structural unit derived from the alkyl (meth)acrylate preferably contains a (meth)acrylate having an alkyl group having from 4 to 8 carbon atoms (hereinafter, sometimes referred to as "alkyl (meth)acrylate (a)"). When the alkyl (meth)acrylate contains the alkyl (meth)acrylate (a), it becomes easier to adjust the glass transition temperature and shear storage modulus of the pressure-sensitive adhesive layer to preferred ranges.

[0060] Examples of the alkyl (meth)acrylate (a) include n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, 1-methylhexyl (meth)acrylate, n-octyl (meth)acrylate, 1-methylheptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Of these, alkyl (meth)acrylates having an alkyl group containing 6 to 8 carbon atoms are preferred. These alkyl (meth)acrylates may be used alone or in combination of two or more. However, from the viewpoint of making it easier to adjust the glass transition temperature and shear storage modulus of the pressure-sensitive adhesive layer to preferred ranges, it is preferable to use two or more in combination. Of these, it is more preferable that the (meth)acrylic copolymer have two or more structural units derived from alkyl (meth)acrylates having an alkyl group containing 6 to 8 carbon atoms.

[0061] The preferred lower limit of the content of the structural units derived from the alkyl (meth)acrylate (a) in the (meth)acrylic copolymer is 50% by mass. When the content of the structural units derived from the alkyl (meth)acrylate (a) is 50% by mass or more, the glass transition temperature and shear storage modulus of the pressure-sensitive adhesive layer can be easily adjusted to preferred ranges. A more preferred lower limit of the content of the structural units derived from the alkyl (meth)acrylate (a) is 60% by mass, and an even more preferred lower limit is 70% by mass. Furthermore, a preferred upper limit of the content of the structural units derived from the alkyl (meth)acrylate (a) is 99% by mass. When the content of the structural units derived from the alkyl (meth)acrylate (a) is 99% by mass or less, the (meth)acrylic copolymer can have structural units derived from the monomer having the crosslinkable functional group, making it easier for the pressure-sensitive adhesive layer to form a crosslinked structure. The upper limit of the content of the structural units derived from the alkyl (meth)acrylate (a) is more preferably 97% by mass, and even more preferably 95% by mass. The content of the structural units derived from the alkyl (meth)acrylate (a) can be determined by mass spectrometry and 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.).

[0062] The preferred lower limit of the content of the structural units derived from a (meth)acrylate having an alkyl group containing 6 to 8 carbon atoms in the (meth)acrylic copolymer is 50% by mass. When the content of the structural units derived from a (meth)acrylate having an alkyl group containing 6 to 8 alkyl carbon atoms is 50% by mass or more, the glass transition temperature and shear storage modulus of the pressure-sensitive adhesive layer can be more easily adjusted within preferred ranges. A more preferred lower limit of the content of the structural units derived from a (meth)acrylate having an alkyl group containing 6 to 8 carbon atoms is 60% by mass, and an even more preferred lower limit is 70% by mass. Furthermore, a preferred upper limit of the content of the structural units derived from a (meth)acrylate having an alkyl group containing 6 to 8 carbon atoms is 99% by mass. When the content of the structural units derived from a (meth)acrylate having an alkyl group containing 6 to 8 carbon atoms is 99% by mass or less, the (meth)acrylic copolymer can contain structural units derived from a monomer having the crosslinkable functional group, making it easier for the pressure-sensitive adhesive layer to form a crosslinked structure. A more preferred upper limit of the content of the structural units derived from a (meth)acrylate having an alkyl group having from 6 to 8 carbon atoms is 97% by mass, and an even more preferred upper limit is 95% by mass. From the viewpoint of imparting better stress relaxation properties to a pressure-sensitive adhesive layer that conforms to a curved surface, when the (meth)acrylic copolymer has two or more structural units derived from a (meth)acrylate having an alkyl group having from 6 to 8 carbon atoms, it is more preferred that the total content of the structural units derived from a (meth)acrylate having an alkyl group having from 6 to 8 alkyl carbon atoms satisfies the above-mentioned range.

[0063] The alkyl (meth)acrylate in the structural unit derived from the alkyl (meth)acrylate preferably contains an alkyl (meth)acrylate having a linear alkyl group (hereinafter, sometimes referred to as "alkyl (meth)acrylate (b)"). By containing the alkyl (meth)acrylate (b), it becomes easier to adjust the weight average molecular weight of the (meth)acrylic copolymer to a preferred range.

[0064] Examples of the alkyl (meth)acrylate (b) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, etc. These alkyl (meth)acrylates may be used alone or in combination of two or more.

[0065] The content of the structural units derived from the alkyl (meth)acrylate (b) in the (meth)acrylic copolymer is preferably 50% by mass at a lower limit. When the content of the structural units derived from the alkyl (meth)acrylate (b) is 50% by mass or more, it becomes easier to adjust the weight-average molecular weight of the (meth)acrylic copolymer to a preferred range. The content of the structural units derived from the alkyl (meth)acrylate (b) is more preferably 60% by mass at a lower limit, and even more preferably 70% by mass at a lower limit. Furthermore, the content of the structural units derived from the alkyl (meth)acrylate (b) is preferably 99% by mass at an upper limit. When the content of the structural units derived from the alkyl (meth)acrylate (b) is 99% by mass or less, the (meth)acrylic copolymer can contain structural units derived from the monomer having the crosslinkable functional group, which makes it easier for the pressure-sensitive adhesive layer to form a crosslinked structure. The content of the structural units derived from the alkyl (meth)acrylate (b) is more preferably 95% by mass at an upper limit, and even more preferably 90% by mass at an upper limit. The content of the structural unit derived from the alkyl (meth)acrylate (b) was determined by mass spectrometry and nuclear magnetic resonance spectroscopy of the (meth)acrylic copolymer ( 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.).

[0066] The alkyl(meth)acrylate preferably includes, as the alkyl(meth)acrylate (a) and the alkyl(meth)acrylate (b), an alkyl(meth)acrylate having a linear alkyl group having 4 to 8 carbon atoms.

[0067] The alkyl (meth)acrylate preferably contains an alkyl (meth)acrylate having a boiling point of 250°C or lower. By containing an alkyl (meth)acrylate having a boiling point of 250°C or lower, it becomes easier to adjust the polydispersity of the (meth)acrylic copolymer to a preferred range. The upper limit of the boiling point of the alkyl (meth)acrylate having a boiling point of 250°C or lower is more preferably 230°C, and even more preferably 220°C. Furthermore, from the viewpoint of ensuring that the pressure-sensitive adhesive layer has adequate bulk strength, the lower limit of the boiling point of the alkyl (meth)acrylate having a boiling point of 250°C or lower is preferably 100°C, and more preferably 150°C. In this specification, the "boiling point of the alkyl (meth)acrylate" means the boiling point at 101 kPa.

[0068] Examples of alkyl (meth)acrylates having a boiling point of 250°C or lower include n-butyl acrylate (boiling point: 145°C), n-butyl methacrylate (boiling point: 163°C), n-hexyl acrylate (boiling point: 195°C), n-hexyl methacrylate (boiling point: 88°C), n-heptyl acrylate (boiling point: 222°C), n-heptyl methacrylate (boiling point: 229°C), 1-methylheptyl acrylate (boiling point: 218°C), 1-methylheptyl methacrylate (boiling point: 79°C), 2-ethylhexyl acrylate (boiling point: 215°C), and 2-ethylhexyl methacrylate (boiling point: 214°C). Of these, n-hexyl acrylate, n-heptyl acrylate, and 1-methylheptyl acrylate are preferred.

[0069] The alkyl (meth)acrylate preferably contains an alkyl (meth)acrylate having a glass transition temperature of -50°C or lower when made into a homopolymer. By containing an alkyl (meth)acrylate having a glass transition temperature of -50°C or lower when made into a homopolymer, the flexibility of the pressure-sensitive adhesive layer is further improved. The upper limit of the glass transition temperature of the alkyl (meth)acrylate having a glass transition temperature of -50°C or lower when made into a homopolymer is more preferably -60°C, and even more preferably -65°C. Furthermore, from the viewpoint of achieving appropriate bulk strength, the lower limit of the glass transition temperature of the alkyl (meth)acrylate having a glass transition temperature of -50°C or lower when made into a homopolymer is preferably -100°C, and more preferably -80°C. In this specification, the term "glass transition temperature when made into a homopolymer" refers to the glass transition temperature of a homopolymer of alkyl (meth)acrylate having a weight average molecular weight of 100,000 to 2,000,000, measured by differential scanning calorimetry. 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.

[0070] Examples of the alkyl(meth)acrylate having a glass transition temperature of −50° C. or lower when made into a homopolymer include n-butyl acrylate (glass transition temperature when made into a homopolymer: −54° C.), n-hexyl acrylate (glass transition temperature when made into a homopolymer: −65° C.), and n-heptyl acrylate (glass transition temperature when made into a homopolymer: −68° C.). Of these, n-hexyl acrylate and n-heptyl acrylate are preferred.

[0071] 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 250°C or lower, and the alkyl (meth)acrylate having a glass transition temperature of -50°C or lower when formed into a homopolymer.

[0072] 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, which is also preferable from the viewpoint of reducing carbon dioxide emissions.

[0073] 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.

[0074] When the (meth)acrylic copolymer has a structural unit derived from the monomer having the crosslinkable functional group, the pressure-sensitive adhesive layer more easily forms a crosslinked structure, and the gel fraction of the pressure-sensitive adhesive layer can be more easily adjusted to a more suitable range.

[0075] 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 makes it easier to adjust the degree of crosslinking of the pressure-sensitive adhesive composition. Furthermore, 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.

[0076] Examples of the carboxy group-containing monomer include (meth)acrylic acid, etc. Examples of the hydroxy 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, and polypropylene glycol mono(meth)acrylate. 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.

[0077] The preferred lower limit of the content of the structural units 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 units 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, and the gel fraction of the pressure-sensitive adhesive layer can be more easily adjusted to a preferred range. When the content of the structural units derived from the monomer having a crosslinkable functional group is 20% by mass or less, the pressure-sensitive adhesive layer has appropriate flexibility. A more preferred lower limit of the content of the structural units derived from the monomer having a crosslinkable functional group is 0.1% by mass, a more preferred upper limit is 10% by mass, an even more preferred lower limit is 0.2% by mass, and an even more preferred upper limit is 7.0% by mass. The content of the structural units derived from the monomer having a crosslinkable functional group in the (meth)acrylic copolymer can be determined by mass spectrometry and 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.

[0078] 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 the gel fraction of the pressure-sensitive adhesive layer is more easily adjusted to a preferred range. 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 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.

[0079] The preferred lower limit of the content of the structural units derived from the carboxy 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 units derived from the carboxy group-containing monomer is within the above range, the pressure-sensitive adhesive layer is more likely to form a crosslinked structure, and the gel fraction of the pressure-sensitive adhesive layer is more easily adjusted to a preferred range. The more preferred lower limit of the content of the structural units derived from the carboxy group-containing monomer is 1.0% by mass, and the more preferred upper limit is 10% by mass, and the even more preferred lower limit is 3.0% by mass, and the even more preferred upper limit is 8.0% by mass. The content of the structural units derived from the carboxy group-containing monomer in the (meth)acrylic copolymer can be determined by mass spectrometry and 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.

[0080] The (meth)acrylic copolymer may contain structural units derived from other monomers other than the structural units derived from the alkyl (meth)acrylate and the structural units derived from the monomer having a crosslinkable functional group, as long as the object of the present invention is not impaired.

[0081] Examples of the other monomers include benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (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.

[0082] The monomer having a crosslinkable functional group and the 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 (meth)acrylic copolymer to be monomers containing biologically derived materials. From the standpoint 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.

[0083] The preferred lower limit of the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 300,000. When the weight-average molecular weight of the (meth)acrylic copolymer is 300,000 or more, the repulsion resistance of the pressure-sensitive adhesive layer is further improved, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can further suppress separator lift-up after being adhered to a curved surface. The more preferred lower limit of the weight-average molecular weight of the (meth)acrylic copolymer is 400,000, and even more preferred is 500,000. The preferred upper limit of the weight-average molecular weight of the (meth)acrylic copolymer is 1,500,000. When the weight-average molecular weight of the (meth)acrylic copolymer is 1,500,000 or less, the stress relaxation property of the pressure-sensitive adhesive layer is further improved, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can further suppress separator lift-up after being adhered to a curved surface. The more preferred upper limit of the weight-average molecular weight of the (meth)acrylic copolymer is 1,400,000, and even more preferred is 1,300,000.

[0084] 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. When the polydispersity of the (meth)acrylic copolymer is 7.0 or less, the stress relaxation properties of the pressure-sensitive adhesive layer are further improved, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can further suppress separator lift-off after being attached to a curved surface. The upper limit of the polydispersity of the (meth)acrylic copolymer is more preferably 5.0, and even more preferably 3.0. Furthermore, the lower limit of the polydispersity of the (meth)acrylic copolymer is preferably 1.1. When the polydispersity of the (meth)acrylic copolymer is 1.1 or more, the pressure-sensitive adhesive can be imparted with appropriate tack, thereby further improving the adhesive strength of the pressure-sensitive adhesive layer. The lower limit of the polydispersity of the (meth)acrylic copolymer (Mw / Mn) is more preferably 2.0.

[0085] 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 pressure-sensitive adhesive layer has appropriate bulk strength, thereby further improving the handleability of the separator-attached double-sided pressure-sensitive adhesive tape that is one embodiment of the present invention.

[0086] In this specification, the weight average molecular weight and the number molecular weight are weight average molecular weight and number average molecular weight in terms of standard polystyrene measured 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.

[0087] 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 layer 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 layer 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.

[0088] 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 organic tellurium polymerization initiator is one that is generally used in living radical polymerization, and examples thereof include organic tellurium compounds, organic telluride compounds, etc. In addition to the organic tellurium polymerization initiator, the azo compound may also be used in the living radical polymerization in order to accelerate the polymerization rate.

[0089] The preferred lower limit of the content of the (meth)acrylic copolymer in the acrylic 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 separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can further prevent the separator from lifting off the pressure-sensitive adhesive tape, both immediately after being attached to a curved surface and long after being attached to the curved surface. The more preferred lower limit of the (meth)acrylic copolymer content is 55% by mass, and the more preferred upper limit is 80% by mass.

[0090] The pressure-sensitive adhesive composition preferably contains a tackifier resin, which allows the pressure-sensitive adhesive layer to have superior adhesive strength.

[0091] Examples of the tackifier resin include rosin ester tackifier resins, terpene tackifier resins, terpene phenol tackifier resins, coumarone-indene tackifier resins, alicyclic saturated hydrocarbon tackifier resins, C5 petroleum tackifier resins, C9 petroleum tackifier resins, and C5-C9 copolymer petroleum tackifier resins. Among these, at least one selected from the group consisting of rosin ester tackifier resins and terpene phenol tackifier resins is preferred from the viewpoint of excellent compatibility with the (meth)acrylic copolymer. These tackifier resins may be used alone or in combination of two or more.

[0092] Examples of the rosin ester-based tackifying resin include polymerized rosin ester-based resins and hydrogenated rosin ester-based resins. The rosin ester-based tackifying resins and the terpene phenol-based tackifying resins are preferably derived from living organisms. Examples of the rosin ester-based tackifying resins derived from living organisms include rosin ester-based tackifying resins derived from natural resins such as pine resin. Examples of the terpene-based tackifying resins derived from living organisms include terpene-based tackifying resins derived from plant essential oils.

[0093] Specific examples of the rosin ester-based tackifying resins 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 phenol-based tackifying resins include YS Resin PX1250 and YS Polystar G150 (all manufactured by Yasuhara Chemical Co., Ltd.).

[0094] The tackifier resin preferably contains a tackifier resin having a softening point of 80°C or higher and 170°C or lower. When the tackifier resin contains a tackifier resin having a softening point of 80°C or higher and 170°C or lower, the PSA layer and the separator-attached double-sided PSA tape of one embodiment of the present invention will have better heat resistance. A more preferred lower limit of the softening point of the tackifier resin is 100°C, a more preferred upper limit is 160°C, an even more preferred lower limit is 120°C, and an even more preferred upper limit is 150°C. 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).

[0095] The tackifier resin preferably contains a tackifier resin having a hydroxyl value of 20 mgKOH / g or more and 150 mgKOH / g or less. By containing a tackifier resin having a hydroxyl value of 20 mgKOH / g or more and 150 mgKOH / g or less, compatibility with the (meth)acrylic copolymer is further improved. Furthermore, the degree of crosslinking of the pressure-sensitive adhesive layer can be easily adjusted within a suitable range. The hydroxyl value of the tackifier resin is more preferably 30 mgKOH / g at its lower limit, 120 mgKOH / g at its upper limit, 40 mgKOH / g at its even lower limit, and 100 mgKOH / g at its upper limit. The hydroxyl value can be measured according to JIS K1557 (phthalic anhydride method).

[0096] When the pressure-sensitive adhesive composition is the acrylic pressure-sensitive adhesive composition, the preferred lower limit of the content of the tackifier resin relative to 100 parts by mass of the (meth)acrylic copolymer in the pressure-sensitive adhesive composition is 10 parts by mass, and the preferred upper limit is 50 parts by mass. By having the content of the tackifier resin within the above range, the adhesive strength of the pressure-sensitive adhesive layer is further improved. The more preferred lower limit of the content of the tackifier resin is 15 parts by mass, the more preferred upper limit is 45 parts by mass, the even more preferred lower limit is 20 parts by mass, and the even more preferred upper limit is 40 parts by mass.

[0097] The pressure-sensitive adhesive composition preferably contains a crosslinking agent from the viewpoint of being able to appropriately adjust 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-based crosslinking agent. Among these, the crosslinking agent preferably includes at least one selected from the group consisting of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent. The crosslinking agent may be a single agent, or two or more types may be used in combination. 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 (e.g., two or more 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 (e.g., one or more types of isocyanate-based crosslinking agents and one or more types of epoxy-based crosslinking agents may be used).

[0098] When the pressure-sensitive adhesive composition is the acrylic 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 in the pressure-sensitive adhesive composition is 0.01 parts by mass, and the preferred upper limit is 10 parts by mass. When the content of the crosslinking agent is within the above range, it becomes easier to adjust the degree of crosslinking of the pressure-sensitive adhesive layer within a preferred range, and therefore it becomes easier to adjust the gel fraction of the pressure-sensitive adhesive layer within a preferred range. A more preferred lower limit of the content of the crosslinking agent is 0.1 parts by mass, a more preferred upper limit is 7.0 parts by mass, an even more preferred lower limit is 0.2 parts by mass, and an even more preferred upper limit is 5.0 parts by mass. In this specification, the "content of crosslinking agent" refers to the content of the solids of the crosslinking agent.

[0099] 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.

[0100] 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.

[0101] 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 pressure-sensitive adhesive tape according to one embodiment of the present invention is excellent in terms of saving petroleum resources and reducing carbon dioxide emissions, and is therefore able to reduce the environmental impact. A more preferred lower limit of the bio-derived carbon content in the pressure-sensitive adhesive layer is 40%, and an even more preferred lower limit is 60%. The upper limit of the bio-derived carbon content in the pressure-sensitive adhesive layer may be, for example, 100%. While bio-derived carbon contains a certain proportion of the radioactive isotope (C-14), petroleum-derived carbon contains almost no C-14. Therefore, the "biological carbon content" in this specification can be calculated by measuring the concentration of C-14 contained in the pressure-sensitive adhesive layer. Specifically, it can be measured in accordance with ASTM D6866-24, a standard widely used in the bioplastics industry.

[0102] The double-sided pressure-sensitive adhesive tape may be a non-support type tape that does not have a base layer, or may be a supported type sheet that has a base layer. In particular, it is preferable that the double-sided pressure-sensitive adhesive tape does not have a base layer, as this makes the double-sided pressure-sensitive adhesive tape more flexible.

[0103] When the double-sided pressure-sensitive adhesive tape has a substrate layer, examples of the substrate used for the substrate layer include paper, resin film, nonwoven fabric, foam substrate, etc. Among these, a resin film is preferred from the viewpoints of making it easy to adjust the thickness and making the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention less prone to wrinkling.

[0104] The substrate used in the substrate layer is preferably a substrate made of a bio-derived material, from the viewpoint of increasing the content of bio-derived carbon in the entire pressure-sensitive adhesive tape. Examples of the bio-derived material include polyesters (PES) such as polyethylene terephthalate (PET), polyethylene furanoate (PEF), polylactic acid (PLA), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), and polybutylene succinate (PBS), polyethylene (PE), polypropylene (PP), polyurethane (PU), triacetyl cellulose (TAC), cellulose, and polyamide (PA), which are derived from plants.

[0105] 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.

[0106] 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.

[0107] The foam substrate is preferably a foam substrate containing at least one selected from the group consisting of PE, PP, and PU, and from the viewpoint of achieving a high degree of both flexibility and strength, a foam substrate containing PE is more preferred. Examples of the constituent of the foam substrate containing PE include PE made from sugarcane.

[0108] 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.

[0109] When the substrate layer is subjected to a dumbbell tensile test at a tensile speed of 100 mm / min, the substrate layer does not break when elongated by 2.0% in length, and the tensile strength when the substrate layer elongates by 2.0% in length (hereinafter sometimes simply referred to as the "tensile strength of the substrate layer") is preferably 17 N. When the tensile strength of the substrate layer is 17 N or less, the separator-equipped double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more easily stretched to conform to a curved surface and bonded to it. A more preferred upper limit of the tensile strength of the substrate layer is 15 N, and an even more preferred upper limit is 12 N. Furthermore, a preferred lower limit of the tensile strength of the substrate layer is 1.0 N. When the tensile strength of the substrate layer is 1.0 N or more, the separator-equipped double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more easily prevented from unintentional stretching, and therefore the separator-equipped double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more easily bonded to a curved surface. A more preferred lower limit of the tensile strength of the substrate layer is 2.0 N, and an even more preferred lower limit is 3.0 N.

[0110] The tensile strength of the substrate layer can be controlled by adjusting the type and thickness of the substrate.

[0111] When a dumbbell tensile test is performed on the base material layer at a tension speed of 100 mm / min, the preferred upper limit of the tensile modulus at a displacement strain of 0.8 to 1.5% (hereinafter sometimes simply referred to as the "tensile modulus of the base material layer") is 5000 MPa. When the tensile modulus of the base material layer is 5000 MPa or less, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention becomes more flexible, and therefore the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more effectively prevented from wrinkling when it is attached to a curved surface. A more preferred upper limit of the tensile modulus of the base material layer is 3000 MPa, and an even more preferred upper limit is 2000 MPa. Furthermore, a preferred lower limit of the tensile modulus of the base material layer is 1.0 MPa. When the tensile modulus of the base material layer is 1.0 MPa or more, the pressure-sensitive adhesive layer can be prevented from stretching too much when the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention is attached to a curved surface, resulting in better adhesive strength to curved surfaces. The lower limit of the tensile modulus of elasticity of the substrate layer is more preferably 5.0 MPa, and even more preferably 10 MPa.

[0112] The tensile modulus of the substrate layer can be controlled by adjusting the type of substrate.

[0113] When a dumbbell tensile test is performed on the base layer at a tensile speed of 100 mm / min, the tensile elongation at break (hereinafter sometimes simply referred to as "tensile elongation at break of the base layer") preferably has a lower limit of 40 mm and a preferred upper limit of 400 mm. When the tensile elongation at break of the base layer is 40 mm or more, the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can be more easily conformed to curved surfaces and bonded to them without breaking the base layer. When the tensile elongation at break of the base layer is 400 mm or less, the base layer does not become too flexible, and the separator-attached double-sided pressure-sensitive adhesive tape of one embodiment of the present invention has excellent handleability and is easier to bond to them. The tensile elongation at break of the base layer is more preferably 50 mm lower, more preferably 350 mm upper, even more preferably 100 mm lower, and even more preferably 330 mm upper.

[0114] The tensile elongation at break of the substrate layer can be controlled by adjusting the type and thickness of the substrate.

[0115] The preferred upper limit of the thickness of the substrate layer is 100 μm. When the thickness of the substrate layer is 100 μm or less, the separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention becomes more flexible, and the occurrence of wrinkles when the tape is attached to a curved surface can be more effectively prevented. The preferred upper limit of the thickness of the substrate layer is 75 μm, and even more preferably 50 μm. Furthermore, from the viewpoint of improving the yield of the adhesive tape attachment operation and ensuring the thickness of the pressure-sensitive adhesive layer, the preferred lower limit of the substrate layer is 2.0 μm, and more preferably 4.0 μm.

[0116] The preferred lower limit of the total thickness of the double-sided pressure-sensitive adhesive tape (the sum of the thickness of the base layer and the thickness of the pressure-sensitive adhesive layer) is 3.0 μm, and the preferred upper limit is 6000 μm. Having the total thickness of the double-sided pressure-sensitive adhesive tape within this range further increases the adhesive strength of the separator-attached double-sided pressure-sensitive adhesive tape, which is one embodiment of the present invention. The more preferred upper limit of the total thickness of the double-sided pressure-sensitive adhesive tape is 1200 μm, and even more preferred upper limit is 500 μm.

[0117] The separator-attached double-sided pressure-sensitive adhesive tape according to one embodiment of the present invention can be produced, for example, by the following method in the case of a double-sided pressure-sensitive adhesive tape having a substrate. First, a solvent is added to a (meth)acrylic copolymer and, if necessary, a tackifier resin, a crosslinking agent, etc. to prepare a pressure-sensitive adhesive composition A. The obtained pressure-sensitive adhesive composition A is applied to the surface of the substrate, and the solvent in the composition is completely dried and removed by heating to form a pressure-sensitive adhesive layer A. Next, a separator is superimposed on the formed pressure-sensitive adhesive layer A with its release-treated surface facing the pressure-sensitive adhesive layer A. Next, a separator other than the above separator is prepared, and pressure-sensitive adhesive composition B prepared in the same manner as the pressure-sensitive adhesive composition A is applied to this separator, 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 separator. The obtained laminate film is superimposed on the back surface of the substrate layer on which pressure-sensitive adhesive layer A has been formed, with the pressure-sensitive adhesive layer B facing the back surface of the substrate layer to produce a laminate. Then, by pressing the laminate with a rubber roller or the like, a separator-attached double-sided adhesive tape can be obtained, which has a double-sided adhesive tape with a base layer and both sides of the adhesive tape are covered with separators.

[0118] 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 layers of the laminate films 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 layer and in which the surfaces of the pressure-sensitive adhesive layers are covered with a separator.

[0119] The separator-equipped double-sided pressure-sensitive adhesive tape of one embodiment of the present invention is preferably used for fixing electronic components or vehicle-mounted components. Specifically, the pressure-sensitive adhesive tape of one embodiment of the present invention can be suitably used for adhesively fixing electronic components in large portable electronic devices and vehicle-mounted components (e.g., vehicle panels). In particular, the separator-equipped double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can prevent the separator (the separator on the side of the adhesive tape that is not attached to the curved surface) from lifting off the adhesive tape when attached to a curved surface, making it more suitable for fixing electronic components having curved surfaces. In particular, the separator-equipped double-sided pressure-sensitive adhesive tape of one embodiment of the present invention can exhibit adhesive strength from the initial stage of attachment, making it more suitable for use in electronic device manufacturing processes in which the process of attaching the adhesive tape to a curved module and the process of attaching the curved electronic components are performed at different locations. Examples of electronic component parts having curved surfaces include OLED panels. Furthermore, in a preferred embodiment of the separator-attached double-sided pressure-sensitive adhesive tape according to the present invention, the separator can be prevented from lifting off the pressure-sensitive adhesive tape even long after it has been attached to a curved surface, making it even more suitable for use in fixing electronic components having curved surfaces. Therefore, the tape can be even more suitable for use in electronic device manufacturing processes in which the step of attaching the pressure-sensitive adhesive tape to a module and the step of attaching the curved electronic component are carried out at different locations.

[0120] According to the present invention, it is possible to provide a double-sided adhesive tape with a separator that can prevent the separator from lifting off the adhesive tape when the tape is attached to a curved surface.

[0121] 1A and 1B are top views each schematically showing the application of an adhesive tape to a flat portion of an SUS plate in the preparation of a measurement sample for evaluation, and FIG. 1C are views each schematically showing the application of an adhesive tape to a curved portion of an SUS plate in the preparation of a measurement sample for evaluation.

[0122] 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.

[0123] <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.

[0124] <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.

[0125] <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.).

[0126] <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.

[0127] <Bio-derived carbon-free monomers> n-butyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) 2-ethylhexyl acrylate (manufactured by Nippon Shokubai Co., Ltd.) Acrylic acid (manufactured by Nippon Shokubai Co., Ltd.)

[0128] <Tackifying Resins> Tackifying resin A: rosin ester tackifying resin (softening point: 150°C, hydroxyl value: 35 mgKOH / g) Tackifying resin B: rosin ester tackifying resin (manufactured by Arakawa Chemical Industries, Ltd., "Pine Crystal KE-359", softening point: 100°C, hydroxyl value: 40 mgKOH / g) Tackifying resin C: terpene phenol tackifying resin (manufactured by Yasuhara Chemical Co., Ltd., "YS Polystar G150", softening point: 150°C, hydroxyl value: 130 mgKOH / g)

[0129] <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")

[0130] 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 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 11.0 parts by mass of n-hexyl acrylate containing bio-derived carbon, 83.9 parts by mass of n-heptyl 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 (meth)acrylic copolymer was measured, and the weight average molecular weight and polydispersity were determined. The results are shown in Table 1.

[0131] (2) Production of Pressure-Sensitive Adhesive Tape To the obtained (meth)acrylic copolymer-containing solution, 15.0 parts by mass of tackifier resin A, 10.0 parts by mass of tackifier resin B, 10.0 parts by mass of tackifier resin C, and an isocyanate-based crosslinking agent in an amount such that the solid content of the crosslinking agent was 2.5 parts by mass relative to 100 parts by mass of the (meth)acrylic copolymer in the (meth)acrylic copolymer-containing solution were added to prepare a pressure-sensitive adhesive composition 1. The obtained pressure-sensitive adhesive composition 1 was applied to the release-treated surface of a 40 μm-thick CPP film 1 (first separator) so that the thickness of the pressure-sensitive adhesive layer after drying would be 35 μm, and the coating was dried at 110° C. for 5 minutes to form a first pressure-sensitive adhesive layer. The formed first pressure-sensitive adhesive layer was then placed on the release-treated surface of a 25 μm-thick PET film 6 (second separator) and aged at 40° C. for 48 hours to obtain a separator-attached double-sided pressure-sensitive adhesive tape (non-support type).

[0132] (3) Measurement of Laminate Tensile Strength After peeling off the second separator from the obtained separator-attached double-sided pressure-sensitive adhesive tape, a dumbbell-shaped punch was used to punch out the laminate comprising the first laminate and the first pressure-sensitive adhesive layer using a punching blade (manufactured by Kobunshi Keiki Co., Ltd., "Tensile No. 3 Dumbbell Shape") to prepare a test specimen. The obtained test specimen was subjected to a dumbbell tensile test using a tensile tester (manufactured by Shimadzu Corporation, "Autograph AGS-X"), with the distance between the grippers set to 40 mm, at a tensile speed of 100 mm / min, until the test specimen broke. In the dumbbell tensile test, the stress measured when the test specimen was elongated by 2.0% was taken as the tensile strength (N). The results are shown in Table 2.

[0133] (4) Measurement of slope in dumbbell tensile test of laminate In the dumbbell tensile test described above in "(3) Measurement of tensile strength of laminate," the slope (N / mm) of the line at a displacement strain of 0.8 to 1.5% was calculated from the obtained S-S curve. The results are shown in Table 2.

[0134] (5) Measurement of tensile breaking strength of laminate In the dumbbell tensile test described above in "(3) Measurement of tensile strength of laminate," the tensile breaking strength (N) of the laminate was calculated from the breaking strength per unit area when the test piece broke. The results are shown in Table 2.

[0135] (6) Measurement of tensile elongation at break of laminate In the dumbbell tensile test in "(3) Measurement of tensile strength of laminate" described above, the displacement from the distance between the grippers at the start of the dumbbell tensile test (initial distance between the grippers) to the distance between the grippers when the test piece broke was taken as the tensile elongation at break (mm). The results are shown in Table 2.

[0136] (7) Measurement of tensile elongation at break of laminate In the dumbbell tensile test described above in "(3) Measurement of tensile strength of laminate," the tensile elongation at break was calculated using the distance between the grippers when the obtained test piece broke, according to the following formula (I). The results are shown in Table 2. Tensile elongation at break (%) = (distance between grippers at break / initial distance between grippers) × 100 (I)

[0137] (8) Measurement of Hysteresis Loss Rate of Laminate In accordance with JIS K 6400-2, the laminate was punched into a dumbbell shape using a punching blade ("Tensile No. 3 Dumbbell" manufactured by Kobunshi Keiki Co., Ltd.) to prepare a test specimen. The obtained test specimen was subjected to a tensile test using a tensile tester ("Autograph AGS-X" manufactured by Shimadzu Corporation) with the distance between the grippers set to 40 mm. The test specimen was pulled 1 mm at a tensile speed of 100 mm / min, held in this state for 1 second, and then released at the same speed. The hysteresis loss rate (%) was calculated using the obtained force-deflection curve. The results are shown in Table 2.

[0138] (9) Measurement of tensile strength of first separator The tensile strength (N) of the first separator was measured in the same manner as in "(3) Measurement of tensile strength of laminate" above, except that only the first separator was used instead of the laminate. The results are shown in Table 2.

[0139] (10) Measurement of tensile modulus of first separator A dumbbell tensile test was performed on the first separator in the same manner as in "(3) Measurement of tensile strength of laminate" above, except that only the first separator was used instead of the laminate, and the tensile modulus of the first separator (MPa) was calculated from a displacement strain of 0.8 to 1.5%. The results are shown in Table 2.

[0140] (11) Measurement of tensile elongation at break of first separator The tensile elongation at break (mm) of the first separator was measured in the same manner as in "(6) Measurement of tensile elongation at break of laminate" above, except that only the first separator was used instead of the laminate. The results are shown in Table 2.

[0141] (12) Measurement of 180° Peel Strength of First Separator from First Pressure-Sensitive Adhesive Layer The obtained separator-attached double-sided pressure-sensitive adhesive tape was cut to a size of 50 mm wide x 100 mm long, and then the second separator was peeled off. The exposed pressure-sensitive adhesive layer was backed with a 50 μm-thick PET film (manufactured by Toyobo Co., Ltd., "E5200#50") to prepare a test specimen. The prepared test specimen was then subjected to a peel test in accordance with JIS Z 0237:2009 using a tensile tester (manufactured by Shimadzu Corporation, "Autograph AGS-X") at 23°C and a peel rate of 300 mm / min, in which the first separator was peeled off from the pressure-sensitive adhesive layer in a 180° direction. The 180° peel strength (N / 50 mm) of the first separator from the first pressure-sensitive adhesive layer was measured. The results are shown in Table 2.

[0142] (13) Measurement of Glass Transition Temperature of First Pressure-Sensitive Adhesive Layer The separators on both sides of the obtained separator-attached double-sided pressure-sensitive adhesive tape were peeled off, and the pressure-sensitive adhesive layers were stacked to produce a laminate approximately 1 mm thick. This laminate was then cut into a width of 6 mm and a length of 10 mm to obtain a test specimen. The obtained test specimen was then 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%, to obtain the glass transition temperature (°C) of the first pressure-sensitive adhesive layer. The results are shown in Table 2.

[0143] (14) Measurement of shear storage modulus of first pressure-sensitive adhesive layer The shear storage modulus (Pa) of the first pressure-sensitive adhesive layer was obtained at 0° C., 25° C., and 85° C. by the dynamic viscoelasticity measurement in "(12) Measurement of glass transition temperature of first pressure-sensitive adhesive layer" described above. The results are shown in Table 2.

[0144] (15) Measurement of gel fraction of first pressure-sensitive adhesive layer The separator was peeled off from one side of the obtained separator-attached double-sided pressure-sensitive adhesive tape, and the tape was cut into a flat rectangular shape with a width of 20 mm and a length of 40 mm. The separator was then peeled off from the other side of the separator-attached double-sided pressure-sensitive adhesive tape to prepare a test piece, and its mass was measured. The test piece was immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate, and dried at 110°C for 1 hour. The mass of the dried test piece was measured, and the gel fraction (mass%) was calculated using the following formula (II). The results are shown in Table 2. Gel fraction (mass%) = 100 x (W ２ -W ０ ) / (W １ -W ０ ) (II) (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)

[0145] (16) Measurement of 180° peel strength of adhesive layer against SUS at 23°C After cutting the obtained separator-attached double-sided adhesive tape to a size of 25 mm wide x 100 mm long, the first separator (the separator on the side not being measured) was peeled off, and the exposed first adhesive layer was backed with a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., "E5200#50") to prepare a test piece. After peeling off the second separator (the separator on the side being measured) of the obtained test piece, the test piece was pressed against a SUS plate (SUS304 plate washed with alcohol and then wiped dry) using a 2 kg rubber roller reciprocating once at a speed of 10 mm / s in an environment of 23°C, and then left to stand in an environment of 23°C for 5 minutes to prepare a measurement sample. The obtained measurement sample was then subjected to a peel test in accordance with JIS Z 0237:2009 using a tensile tester (Shimadzu Corporation, "Autograph AGS-X") in which the pressure-sensitive adhesive tape was peeled from a SUS plate in a direction of 180° at 23°C and a peel rate of 300 mm / min, thereby measuring the 180° peel strength (N / 25 mm) of the pressure-sensitive adhesive layer from SUS at 23°C. The results are shown in Table 2.

[0146] (Examples 2 to 10, 12 to 19, 27 to 30, Comparative Examples 1 to 4) Separator-attached double-sided pressure-sensitive adhesive tapes were obtained in the same manner as in Example 1, except that the types and amounts of monomers constituting the (meth)acrylic copolymer, the types and amounts of each component of the pressure-sensitive adhesive composition, and the type of separator used were as shown in Tables 2 to 5. Measurements were also carried out in the same manner as in Example 1. The results are shown in Tables 2 to 5.

[0147] Examples 11, 20 to 26 Pressure-sensitive adhesive compositions were prepared in the same manner as in Example 1, except that the types and amounts of monomers constituting the (meth)acrylic copolymer and the types and amounts of each component of the pressure-sensitive adhesive composition were as shown in Table 1. The resulting pressure-sensitive adhesive composition was applied to a first separator shown in Tables 3 to 4 so that the thickness of the pressure-sensitive adhesive layer after drying would be as shown in Tables 3 to 4, and then dried at 110°C for 5 minutes, thereby overlaying the resulting first pressure-sensitive adhesive layer on one side of a base layer shown in Tables 3 to 4. Furthermore, a second pressure-sensitive adhesive layer having the composition and thickness shown in Tables 3 to 4, prepared on a second separator shown in Tables 3 to 4 in the same manner as for the first pressure-sensitive adhesive layer, was overlaid on the other side of the base layer, and the resulting layer was aged at 40°C for 48 hours, thereby obtaining a separator-attached double-sided pressure-sensitive adhesive tape (support type) having a base layer, and measurements were performed. The results are shown in Tables 3 to 4. The gel fraction of the first pressure-sensitive adhesive layer was measured using a test piece obtained by laminating the first pressure-sensitive adhesive layer before laminating it to a 23 μm-thick PET substrate film ("FE2002" manufactured by Futamura Chemical Co., Ltd.) and cutting it into a flat rectangular shape with a width of 20 mm and a length of 40 mm, followed by peeling off the first separator. The glass transition temperature and shear storage modulus of the first pressure-sensitive adhesive layer were measured using a laminate of the first pressure-sensitive adhesive layer before laminating it to the substrate layer, which was approximately 1 mm thick, and then cut into a width of 6 mm and a length of 10 mm to obtain a test piece. Furthermore, the tensile strength, tensile modulus, and tensile elongation at break of the substrate layer were measured in the same manner as for the first separator. Furthermore, the 180° peel strength of the pressure-sensitive adhesive layer against SUS was measured for the second pressure-sensitive adhesive layer.

[0148] The separators used in the examples and comparative examples are as follows. CPP film 1: MT2A (manufactured by Toray Industries, Inc., with Si coating, thickness 40 μm) CPP film 2: CPP-25-SBK0A (manufactured by Fujiko Co., Ltd., with Si coating, thickness 25 μm) LDPE film 1: PE-50-SU-C1 (manufactured by Fujiko Co., Ltd., with Si coating, thickness 50 μm) LDPE film 2: LDPE80X1 (manufactured by Nippa Corporation, with Si coating, thickness 80 μm) LDPE film 3: PE-30-SU-C1 (manufactured by Fujiko Co., Ltd., with Si coating, thickness 30 μm) PBTe (PBT elastomer) film: GP300 (manufactured by Sekisui Chemical Co., Ltd., with Si coating, thickness 15 μm) OPP film 1: OPP-40-SBK3 (manufactured by Fujiko Co., Ltd., with Si coating, thickness 40 μm) PET film 1: SP4020#12 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 12 μm) PET film 2: SP4020#25 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 25 μm) PET film 3: SP4020#38 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 38 μm) PET film 4: SP4020#50 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 50 μm) PET film 5: SP4020#75 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 75 μm) PET film 6: SP4107#25 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 25 μm) PET film 11: SP4020#35 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 38 μm) PBT homopolymer film 1: SP4030B#15 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 15 μm) PBT homopolymer film 2: SP4030B#25 (manufactured by Toyo Cross Co., Ltd., with Si coating, thickness 25 μm)

[0149] The substrate layers used in the examples and comparative examples are as follows: OPP film 2: FOS-BTSK#40 (manufactured by Futamura Chemical Co., Ltd., thickness 40 μm) PET film 7: E5200#25 (manufactured by Toyobo Co., Ltd., thickness 25 μm) PET film 8: E5200#12 (manufactured by Toyobo Co., Ltd., thickness 12 μm) PET film 9: 5AF53 (manufactured by Toray Industries, Inc., thickness 4.5 μm) PET film 10: A film (thickness 10 μm) having a colored shielding layer formed by applying an ink composition (manufactured by Dainichiseika Color & Chemicals Co., Ltd., "SKK1C Black-B") to a thickness of 2.75 μm on each side of 5AF53 (manufactured by Toray Industries, Inc., thickness 4.5 μm) by gravure printing, drying, and then curing at 40° C. for 36 hours.

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] <Evaluation> The separator-attached double-sided pressure-sensitive adhesive tapes obtained in the Examples and Comparative Examples were evaluated by the following methods. The results are shown in Tables 6 to 9.

[0156] (1) Preparation of Measurement Sample A SUS plate 2 measuring 75 mm wide, 150 mm long, and 8 mm thick and having curved surfaces with a radius of 8 mm at all four corners was prepared, and the resulting separator-attached double-sided pressure-sensitive adhesive tape was cut into a size of 30 mm wide and 40 mm long, from which the second separator was peeled off. As shown in Fig. 1, a portion of the pressure-sensitive adhesive tape 1 was overlapped on a portion (width 15 mm, length 25 mm) of the flat surface of the SUS plate 2, and the second pressure-sensitive adhesive layer was bonded so that the remaining portion of the pressure-sensitive adhesive tape 1 was positioned above the curved surface of the SUS plate 2. Thereafter, in an environment of 25°C, the portion of the pressure-sensitive adhesive tape 1 positioned above the curved surface of the SUS plate 2 was bonded to the curved surface of the SUS plate 2 as shown in Fig. 2, to prepare a measurement sample.

[0157] (2) Separator Lifting Immediately After Bonding of Pressure-Sensitive Tape Immediately after preparing the measurement sample in the above-described "(1) Preparation of Measurement Sample" (within 1 minute after bonding), the presence or absence of lifting of the first separator of the pressure-sensitive adhesive tape was visually observed.

[0158] (3) Separator lifting a long time after the adhesive tape was bonded After preparing the measurement sample in the above-mentioned "(1) Preparation of measurement sample", the measurement sample was left to stand for one week in an environment of 25°C, and during the standing period, the presence or absence of lifting of the first separator of the adhesive tape of the measurement sample was visually observed, and if lifting was found, the time at which lifting occurred was recorded. Note that if separator lifting occurred in the above-mentioned "(2) Separator lifting immediately after adhesive tape was bonded", this observation was not performed.

[0159] (4) Separator Lifting After Laminating the Adhesive Tape and Performing a Thermal Cycle After preparing the measurement sample in the above-mentioned "(1) Preparation of Measurement Sample," the prepared measurement sample was set in a thermal shock apparatus (manufactured by Espec Corporation, "TSA-73EL"), and a thermal cycle was performed 30 times, in which the temperature was raised from -40°C to 85°C and then returned to -40°C. After repeating the thermal cycle 30 times, the presence or absence of lifting of the first separator of the adhesive tape of the measurement sample was visually observed. Note that if separator lifting occurred in the above-mentioned "(2) Separator Lifting Immediately After Laminating the Adhesive Tape" or "(3) Separator Lifting Long After Laminating the Adhesive Tape," the observation was not performed.

[0160] (5) Evaluation Evaluation was performed according to the following criteria. ⊚: No separator lifting occurred immediately after the adhesive tape was adhered, after a long time had elapsed since the adhesive tape was adhered, or after the cooling-heating cycle. ◯: No separator lifting occurred immediately after the adhesive tape was adhered or after a long time had elapsed since the adhesive tape was adhered, but separator lifting occurred after the cooling-heating cycle. △: No separator lifting occurred immediately after the adhesive tape was adhered, but separator lifting occurred after a long time had elapsed since the adhesive tape was adhered. ×: The adhesive tape could not be adhered to the SUS plate, or separator lifting occurred immediately after the adhesive tape was adhered. The better the evaluation, the more effectively the separator can be prevented from lifting from the adhesive tape, both immediately after adhesion to a curved surface and after a long time had elapsed since adhesion to a curved surface.

[0161]

[0162]

[0163]

[0164]

[0165] According to the present invention, it is possible to provide a double-sided adhesive tape with a separator that can prevent the separator from lifting off the adhesive tape when the tape is attached to a curved surface.

[0166] 1: Adhesive tape 2: SUS plate

Claims

1. A double-sided adhesive tape with a separator, comprising a double-sided adhesive tape having an adhesive layer and a separator on at least one side of the double-sided adhesive tape, In a dumbbell tensile test performed at a tensile speed of 100 mm / min on a laminate having a separator on one side of the double-sided adhesive tape, the laminate does not break when its length is stretched by 2.0%, and the tensile strength of the laminate when its length is stretched by 2.0% is 17 N or less. A double-sided adhesive tape with a separator, characterized by the following features.

2. The double-sided adhesive tape with separator according to claim 1, wherein when a dumbbell tensile test is performed on the laminate at a tensile speed of 100 mm / min, the slope of the line at a displacement strain of 0.8 to 1.5% is 30 N / mm or less.

3. The double-sided adhesive tape with separator according to claim 1 or 2, wherein the laminate has a hysteresis loss rate of 1.0% or more when its length is extended by 2.5%.

4. The double-sided adhesive tape with separator according to claim 1 or 2, wherein the laminate exhibits a tensile breaking strength of 5.0 N or more when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min.

5. The laminate is a double-sided adhesive tape with a separator according to claim 1 or 2, wherein the thickness of the laminate is 150 μm or less.

6. The double-sided adhesive tape with a separator according to claim 1 or 2, wherein, when a dumbbell tensile test is performed on the separator at a tensile speed of 100 mm / min, the separator does not break when its length elongates by 2.0%, and the tensile strength of the separator when its length elongates by 2.0% is 17 N or less.

7. The double-sided adhesive tape with separator according to claim 1 or 2, wherein the separator has a tensile modulus of elasticity of 5000 MPa or less at a displacement strain of 0.8 to 1.5% when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min.

8. The separator is a double-sided adhesive tape with a separator according to claim 1 or 2, wherein the separator has a 180° peel force from the adhesive layer of 0.05 N / 50 mm or more and 5.0 N / 50 mm or less.

9. The separator is a release-treated film. The thickness is 100 μm or less. Double-sided adhesive tape with separator according to claim 1 or 2.

10. The double-sided adhesive tape with separator according to claim 1 or 2, wherein the thickness of the adhesive layer is 5.0 μm or more.

11. The double-sided adhesive tape with separator according to claim 1 or 2, wherein the adhesive layer has a 180° peel force of 10 N / 25 mm or more against SUS at 23°C.

12. The double-sided adhesive tape with separator according to claim 1 or 2, wherein the adhesive layer has a glass transition temperature of -15°C to 20°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.

13. The adhesive layer has a shear storage modulus of 5.0 × 10⁻¹⁶ at 25°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. ４ Pa or more 50×10 ４ A double-sided adhesive tape with a separator according to claim 1 or 2, wherein the pressure is Pa or less.

14. The adhesive layer is formed using an adhesive composition, The aforementioned adhesive composition is an acrylic adhesive composition, The acrylic adhesive composition contains a (meth)acrylic copolymer having structural units derived from alkyl (meth)acrylate and structural units derived from monomers having crosslinkable functional groups, The gel fraction of the adhesive layer is 70% by mass or less. Double-sided adhesive tape with separator according to claim 1 or 2.

15. The alkyl (meth)acrylate includes an alkyl (meth)acrylate having an alkyl group with 4 to 8 carbon atoms. The double-sided adhesive tape with separator according to claim 14, wherein the (meth)acrylic copolymer contains 50% by mass or more of constituent units derived from alkyl (meth)acrylate having an alkyl group having 4 to 8 carbon atoms.

16. The alkyl (meth)acrylate includes an alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms and 8 or fewer carbon atoms. The double-sided adhesive tape with separator according to claim 15, wherein the (meth)acrylic copolymer contains 50% by mass or more of constituent units derived from alkyl (meth)acrylate having an alkyl group having 6 to 8 carbon atoms.

17. The (meth)acrylic copolymer has two or more constituent units derived from alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms, The double-sided adhesive tape with separator according to claim 16, wherein the total content of constituent units derived from alkyl (meth)acrylate having an alkyl group having 6 or more carbon atoms and 8 carbon atoms is 50% by mass or more.

18. The alkyl (meth)acrylate includes an alkyl (meth)acrylate having a linear alkyl group, The double-sided adhesive tape with separator according to claim 14, wherein the (meth)acrylic copolymer contains 50% by mass or more of constituent units derived from alkyl (meth)acrylate having a linear alkyl group.

19. The double-sided adhesive tape with separator according to claim 14, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having a boiling point of 250°C or less.

20. The double-sided adhesive tape with separator according to claim 14, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate whose glass transition temperature when it is a homopolymer is -50°C or lower.

21. The double-sided adhesive tape with separator according to claim 14, wherein the alkyl (meth)acrylate comprises a material of biological origin.

22. The double-sided adhesive tape with separator according to claim 14, 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.

23. The monomer having the crosslinkable functional group includes a monomer containing a hydroxyl group, The double-sided adhesive tape with separator according to claim 14, 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.

24. The monomer having the crosslinkable functional group includes a monomer containing a carboxyl group, The double-sided adhesive tape with separator according to claim 14, 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.

25. The double-sided adhesive tape with separator according to claim 14, 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.

26. The aforementioned adhesive composition contains a tackifying resin, The double-sided adhesive tape with separator according to claim 1 or 2, wherein the tackifying resin has a softening point of 80°C or more and 170°C or less.

27. The aforementioned adhesive composition contains a tackifying resin, The double-sided adhesive tape with separator according to claim 1 or 2, wherein the tackifying resin comprises a tackifying resin having a hydroxyl value of 20 mg KOH / g or more and 150 mg KOH / g or less.

28. The aforementioned adhesive composition contains a tackifying resin, In the adhesive composition, the content of the tackifying resin relative to 100 parts by mass of the (meth)acrylic copolymer is 10 parts by mass or more and 50 parts by mass or less. Double-sided adhesive tape with separator according to claim 14.

29. The aforementioned adhesive composition contains a crosslinking agent, The double-sided adhesive tape with separator according to claim 14, wherein the crosslinking agent comprises at least one selected from the group consisting of isocyanate-based crosslinking agents and epoxy-based crosslinking agents.

30. 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. Double-sided adhesive tape with separator according to claim 29.

31. The double-sided adhesive tape has a base layer, The thickness of the substrate layer is 100 μm or less. Double-sided adhesive tape with separator according to claim 1 or 2.

32. The double-sided adhesive tape with separator according to claim 1 or 2, wherein the double-sided adhesive tape does not have a base layer.

33. The double-sided adhesive tape with separator according to claim 31, wherein, when a dumbbell tensile test is performed on the base layer at a tensile speed of 100 mm / min, the base layer does not break when its length is stretched by 2.0%, and the tensile strength of the base layer when its length is stretched by 2.0% is 17 N or less.

34. The double-sided adhesive tape with separator according to claim 31, wherein the base layer has a tensile modulus of elasticity of 5000 MPa or less at a displacement strain of 0.8 to 1.5% when subjected to a dumbbell tensile test at a tensile speed of 100 mm / min.