Adhesive tape, adhesive composition, and adhesive

Abstract

The present invention provides an adhesive tape which has an adhesive layer containing an adhesive, and satisfies the first configuration described below.　First configuration: the adhesive contains a crosslinked product which has a vinyl monomer polymer structure and a urethane polymer structure, and in which the vinyl monomer polymer and the urethane polymer are crosslinked by means of a crosslinking agent and the vinyl monomer polymer has a constituent unit that is derived from a compound (C1) selected from among (a), (b), and (c) described below (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate (b) a polymer which has a constituent unit derived from an aromatic group-containing (meth)acrylate and a constituent unit derived from a nitrogen atom-containing (meth)acrylate (c) a polymer which has a constituent unit derived from an aromatic group-containing (meth)acrylate and a polymer which has a constituent unit derived from a nitrogen atom-containing (meth)acrylate

Description

Adhesive tape, adhesive composition, and adhesive

[0001] The present invention relates to a pressure-sensitive adhesive tape. The present invention also relates to a pressure-sensitive adhesive composition. The present invention further relates to a pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition.

[0002] Conventionally, pressure-sensitive adhesive tapes having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive composition have been widely used to fix components in electronic components, 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] Adhesive tapes used in the electronics field require high adhesive strength to ensure long-term reliability, but they also require reworkability, which allows them to be removed without leaving residue on the adherend after application. Generally, improving adhesive strength requires making the adhesive contained in the adhesive layer flexible to improve adhesion, while improving reworkability requires making the adhesive contained in the adhesive layer hard so that the adhesive layer does not break when peeled. Therefore, to improve both adhesive strength and reworkability, it is necessary to achieve both the contradictory properties of softness and hardness of the adhesive.

[0005] An object of the present invention is to provide a pressure-sensitive adhesive tape that exhibits both high adhesive strength and excellent reworkability. Another object of the present invention is to provide a pressure-sensitive adhesive composition that can exhibit both high adhesive strength and excellent reworkability. A further object of the present invention is to provide a pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition.

[0006] Disclosure 1 provides a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive, and satisfying at least one constitution selected from the group consisting of the following first and second constitutions: First constitution: the pressure-sensitive adhesive contains a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure, in which the vinyl monomer polymer and the urethane polymer are crosslinked with a crosslinking agent, and the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from the following (a), (b), or (c): (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate, (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate, or (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate. Second configuration: the pressure-sensitive adhesive layer has a thickness of 50 μm or more, a tensile stress at break of 0.50 MPa or more at 23°C, and a 180° peel strength of the pressure-sensitive adhesive tape from SUS at 23°C and a peel rate of 300 mm / min of 5.0 N / inch or more and 30.0 N / inch or less. Disclosure 2 is the pressure-sensitive adhesive tape of Disclosure 1, wherein the pressure-sensitive adhesive layer has one peak of loss tangent (tan δ) in the temperature range of -10°C to 30°C when measured at a frequency of 1 Hz, and the half-width of the loss tangent peak is 40°C or less, and the pressure-sensitive adhesive layer has a shear storage modulus (G') at 25°C of 1.0 MPa or less. Disclosure 3 is the pressure-sensitive adhesive tape of Disclosure 1 or 2, wherein, in the first configuration, the thickness of the pressure-sensitive adhesive layer is 50 μm or more, the pressure-sensitive adhesive layer has a tensile stress at break of 0.50 MPa or more at 23°C, and the 180° peel strength of the pressure-sensitive adhesive tape from SUS at a peel rate of 300 mm / min at 23°C is 5.0 N / inch or more and 30.0 N / inch or less.Disclosure 4 is the pressure-sensitive adhesive tape of Disclosure 1 or 2, wherein in the second configuration, the pressure-sensitive adhesive contains a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure, and in the crosslinked product, the vinyl monomer polymer and the urethane polymer are crosslinked with a crosslinking agent, and the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from the following (a), (b), or (c): (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate Disclosure 5 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, or 4, wherein the nitrogen atom-containing (meth)acrylate comprises at least one selected from the group consisting of a urethane bond-containing (meth)acrylate and an imide bond-containing (meth)acrylate.

[0014] Disclosure 6 is the pressure-sensitive adhesive tape of Disclosure 5, wherein the nitrogen-containing (meth)acrylate contains a urethane bond-containing (meth)acrylate. Disclosure 7 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, or 6, wherein the content of the structural units derived from the aromatic group-containing (meth)acrylate is 5 parts by mass or more and 95 parts by mass or less per 100 parts by mass of the total of the structural units derived from the aromatic group-containing (meth)acrylate and the structural units derived from the nitrogen atom-containing (meth)acrylate. Disclosure 8 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, or 7, wherein the vinyl monomer polymer further contains structural units derived from a hydroxyl group-containing (meth)acrylate. Disclosure 9 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, or 8, wherein the vinyl monomer polymer further contains structural units derived from an alkyl (meth)acrylate. The present disclosure 10 is the pressure-sensitive adhesive tape of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the urethane polymer has at least one selected from the group consisting of a structural unit derived from a polyether diol, a structural unit derived from a polyester diol, and a structural unit derived from a polycarbonate diol.

[0023] Disclosure 11 is the pressure-sensitive adhesive tape of Disclosure 10, wherein the urethane polymer has at least one selected from the group consisting of a structural unit derived from a polyester diol and a structural unit derived from a polycarbonate diol. Disclosure 12 is the pressure-sensitive adhesive tape of Disclosure 11, wherein the urethane polymer has a structural unit derived from a polycarbonate diol. Disclosure 13 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, wherein the urethane polymer has a structural unit derived from an aromatic group-containing compound. Disclosure 14 is the pressure-sensitive adhesive tape of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13, wherein the content of the urethane polymer is 5 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the total of the vinyl monomer polymer and the urethane polymer.

[0023] Present disclosure 15 is the pressure-sensitive adhesive tape of present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, wherein the pressure-sensitive adhesive further contains a tackifier resin.

[0024] Present disclosure 16 is the pressure-sensitive adhesive tape of present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, wherein the pressure-sensitive adhesive layer has a breaking elongation of 300% or more at 23°C.

[0025] Present disclosure 17 is the pressure-sensitive adhesive tape of present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, wherein the pressure-sensitive adhesive layer has a gel fraction of 30% by mass or more and 99% by mass or less.

[0033] Disclosure 18 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, or 17, wherein the Young's modulus at 23°C of the pressure-sensitive adhesive layer is 0.010 MPa or more and 10 MPa or less. Disclosure 19 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18, which has a substrate and the pressure-sensitive adhesive layer on at least one surface of the substrate. Disclosure 20 is the pressure-sensitive adhesive tape of Disclosure 19, wherein the substrate comprises a foam substrate. Disclosure 21 is the pressure-sensitive adhesive tape of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, or 18, which does not have a substrate.Disclosure 22 is a pressure-sensitive adhesive composition containing a vinyl monomer polymer and a urethane polymer, wherein the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from the following (a), (b), or (c): (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate; (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate; (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate. Disclosure 23 is a pressure-sensitive adhesive composition according to Disclosure 22, wherein the nitrogen atom-containing (meth)acrylate comprises at least one selected from the group consisting of a urethane bond-containing (meth)acrylate and an imide bond-containing (meth)acrylate. Disclosure 24 is a pressure-sensitive adhesive composition according to Disclosure 23, wherein the nitrogen atom-containing (meth)acrylate comprises a urethane bond-containing (meth)acrylate. Disclosure 25 is the pressure-sensitive adhesive composition of Disclosure 22, 23, or 24, wherein the content of the structural units derived from the aromatic group-containing (meth)acrylate is 5 parts by mass or more and 95 parts by mass or less per 100 parts by mass of the total of the structural units derived from the aromatic group-containing (meth)acrylate and the structural units derived from the nitrogen atom-containing (meth)acrylate. Disclosure 26 is the pressure-sensitive adhesive composition of Disclosure 22, 23, 24, or 25, wherein the vinyl monomer polymer further has structural units derived from a hydroxyl group-containing (meth)acrylate. Disclosure 27 is the pressure-sensitive adhesive composition of Disclosure 22, 23, 24, 25, or 26, wherein the vinyl monomer polymer further has structural units derived from an alkyl (meth)acrylate. Disclosure 28 is the PSA composition of Disclosure 22, 23, 24, 25, 26, or 27, wherein the urethane polymer has at least one selected from the group consisting of structural units derived from polyether diol, structural units derived from polyester diol, and structural units derived from polycarbonate diol. Disclosure 29 is the PSA composition of Disclosure 28, wherein the urethane polymer has at least one selected from the group consisting of structural units derived from polyester diol, and structural units derived from polycarbonate diol.

[0023] Disclosure 30 is the PSA composition of Disclosure 29, wherein the urethane polymer has structural units derived from a polycarbonate diol. Disclosure 31 is the PSA composition of Disclosure 22, 23, 24, 25, 26, 27, 28, 29, or 30, wherein the urethane polymer has structural units derived from an aromatic group-containing compound. Disclosure 32 is the PSA composition of Disclosure 22, 23, 24, 25, 26, 27, 28, 29, 30, or 31, wherein the content of the urethane polymer is 5 parts by mass or more and 90 parts by mass or less per 100 parts by mass of the vinyl monomer polymer and the urethane polymer combined. Disclosure 33 is the PSA composition of Disclosure 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, or 32, further comprising a tackifier resin. Disclosure 34 is a pressure-sensitive adhesive comprising a crosslinked product of the vinyl monomer polymer and the urethane polymer in the pressure-sensitive adhesive composition of Disclosures 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, or 33. Disclosure 35 is the pressure-sensitive adhesive of Disclosure 34, in which the vinyl monomer polymer and the urethane polymer in the crosslinked product are crosslinked with a crosslinking agent. The present invention will be described in detail below. Note that, in the pressure-sensitive adhesive tape of the present invention, matters common to the first and second configurations will be described as not particularly specified.

[0007] The present inventors have investigated the composition of a pressure-sensitive adhesive layer and the physical properties of the pressure-sensitive adhesive layer and pressure-sensitive adhesive tape for a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive. Regarding the composition of the pressure-sensitive adhesive layer, they considered using a pressure-sensitive adhesive containing a crosslinked product having a specific urethane polymer structure and a vinyl monomer polymer structure. Furthermore, they considered using a vinyl monomer polymer containing a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate, a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate, or a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a polymer having a structural unit derived from a nitrogen atom-containing (meth)acrylate. Furthermore, regarding the physical properties of the pressure-sensitive adhesive layer and pressure-sensitive adhesive tape, they considered adjusting the thickness and tensile stress at break of the pressure-sensitive adhesive layer, as well as the 180° peel strength of the pressure-sensitive adhesive tape from SUS. As a result, they found that a pressure-sensitive adhesive tape that combines high adhesive strength and excellent reworkability could be obtained, leading to the completion of the present invention.

[0008] The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive. The pressure-sensitive adhesive tape of the present invention satisfies at least one constitution selected from the group consisting of the following first and second constitutions. First constitution: The pressure-sensitive adhesive contains a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure, and in the crosslinked product, the vinyl monomer polymer and the urethane polymer are crosslinked with a crosslinking agent, and the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from the following (a), (b), or (c): (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate; (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate; (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate. Second configuration: the thickness of the pressure-sensitive adhesive layer is 50 μm or more, the tensile stress at break of the pressure-sensitive adhesive layer at 23° C. is 0.50 MPa or more, and the 180° peel strength of the pressure-sensitive adhesive tape from SUS at a peel rate of 300 mm / min at 23° C. is 5.0 N / inch or more and 30.0 N / inch or less. When the pressure-sensitive adhesive tape of the present invention satisfies at least one configuration selected from the group consisting of the first configuration and the second configuration, the pressure-sensitive adhesive tape of the present invention can achieve both high adhesive strength and excellent reworkability.

[0009] In the first configuration, the pressure-sensitive adhesive contains a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure. In the first configuration, the pressure-sensitive adhesive contains the crosslinked product, and the urethane polymer structure of the crosslinked product provides the pressure-sensitive adhesive tape of the present invention with excellent reworkability. Meanwhile, the vinyl monomer polymer structure of the crosslinked product provides the pressure-sensitive adhesive tape of the present invention with high adhesive strength. Furthermore, since the crosslinked product has a structure in which the vinyl monomer polymer structure and the urethane polymer structure are crosslinked, the pressure-sensitive adhesive becomes hard, thereby improving the reworkability of the pressure-sensitive adhesive tape of the present invention. That is, in the first configuration, the pressure-sensitive adhesive contains the crosslinked product, and the pressure-sensitive adhesive tape of the present invention can achieve both high adhesive strength and excellent reworkability. Furthermore, in the second configuration, the pressure-sensitive adhesive preferably contains a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure. In the second configuration, when the pressure-sensitive adhesive contains the crosslinked product, the urethane polymer structure of the crosslinked product provides the pressure-sensitive adhesive tape of the present invention with superior reworkability, while the vinyl monomer polymer structure of the crosslinked product provides the pressure-sensitive adhesive tape with higher adhesive strength. Furthermore, since the crosslinked product has a structure in which the vinyl monomer polymer structure and the urethane polymer structure are crosslinked, the pressure-sensitive adhesive becomes harder, thereby further improving the reworkability of the pressure-sensitive adhesive tape of the present invention. That is, in the second configuration, when the pressure-sensitive adhesive contains the crosslinked product, the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability.

[0010] In the first configuration, the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from the following (a), (b), or (c): (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate; (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate; (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate. The compound (C1) has excellent compatibility with urethane polymers, and therefore, in the first configuration, when the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from (a), (b), or (c), the vinyl monomer polymer has excellent compatibility with the urethane polymer described below. Therefore, crosslinking between the compound (C1) and the vinyl monomer polymer having a structural unit derived from the compound (C1) and the urethane polymer described below proceeds uniformly. As a result, the crosslinked product has a vinyl monomer polymer structure and a urethane polymer structure, and the pressure-sensitive adhesive tape of the present invention can achieve both high adhesive strength and excellent reworkability. Furthermore, the excellent compatibility between the compound (C1) and the urethane polymer allows the pressure-sensitive adhesive layer to suppress interface formation due to microphase separation, making the pressure-sensitive adhesive layer less likely to break when pulled, resulting in the pressure-sensitive adhesive tape of the present invention having excellent reworkability. Furthermore, in the second configuration, it is preferable that the vinyl monomer polymer has a structural unit derived from the compound (C1) selected from the following (a), (b), or (c):(a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate; (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate; (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate. The compound (C1) has excellent compatibility with urethane polymers. Therefore, in the second configuration, when the vinyl monomer polymer has a structural unit derived from the compound (C1) selected from (a), (b), or (c), the vinyl monomer polymer has excellent compatibility with the urethane polymer described below. Therefore, crosslinking between the compound (C1) and the vinyl monomer polymer having a structural unit derived from the compound (C1) and the urethane polymer described below proceeds more uniformly. As a result, the crosslinked product has a vinyl monomer polymer structure and a urethane polymer structure, and the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. Furthermore, since the compatibility between the compound (C1) and the urethane polymer is excellent, the pressure-sensitive adhesive layer can further suppress interface formation due to microphase separation, making the pressure-sensitive adhesive layer less likely to break when pulled, and as a result, the pressure-sensitive adhesive tape of the present invention has excellent reworkability.

[0011] Examples of the aromatic group-containing (meth)acrylate include benzyl acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol acrylate, methylphenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-([1,1'-biphenyl]-2-yloxy)ethyl (meth)acrylate, etc. Among these, phenoxyethyl (meth)acrylate and phenoxydiethylene glycol acrylate are preferred from the viewpoint of adhesive properties.

[0012] The preferred lower limit of the content of the structural units derived from the aromatic group-containing (meth)acrylate in the entire vinyl monomer polymer is 5% by mass, and the preferred upper limit is 95% by mass. When the content of the structural units derived from the aromatic group-containing (meth)acrylate is 5% by mass or more, the pressure-sensitive adhesive becomes harder, thereby improving reworkability. When the content of the structural units derived from the aromatic group-containing (meth)acrylate is 95% by mass or less, the pressure-sensitive adhesive does not become too hard, and the pressure-sensitive adhesive tape of the present invention can exhibit higher adhesive strength. The more preferred lower limit of the content of the structural units derived from the aromatic group-containing (meth)acrylate is 10% by mass, and the more preferred upper limit is 90% by mass, and even more preferred lower limit is 15% by mass, and even more preferred upper limit is 85% by mass.

[0013] Examples of the nitrogen atom-containing (meth)acrylate include urethane bond-containing (meth)acrylate, imide bond-containing (meth)acrylate, (meth)acrylamide, etc. Among these, from the viewpoint of achieving better compatibility with the urethane polymer described below, the nitrogen atom-containing (meth)acrylate preferably includes at least one selected from the group consisting of urethane bond-containing (meth)acrylate and imide bond-containing (meth)acrylate, and more preferably includes urethane bond-containing (meth)acrylate.

[0014] Examples of the urethane bond-containing (meth)acrylate include 1,2-ethanediol 1-acrylate 2-(N-butylcarbamate), etc. Examples of the imide bond-containing (meth)acrylate include N-[2-(acryloyloxy)ethyl]phthalimide, etc.

[0015] The preferred lower limit of the content of the structural units derived from the nitrogen atom-containing (meth)acrylate in the entire vinyl monomer polymer is 5% by mass, and the preferred upper limit is 95% by mass. When the content of the structural units derived from the nitrogen atom-containing (meth)acrylate is 5% by mass or more, the pressure-sensitive adhesive becomes harder, thereby further improving the reworkability of the pressure-sensitive adhesive tape of the present invention. When the content of the structural units derived from the nitrogen atom-containing (meth)acrylate is 95% by mass or less, the pressure-sensitive adhesive does not become too hard, and the pressure-sensitive adhesive tape of the present invention can exhibit higher adhesive strength. The more preferred lower limit of the content of the structural units derived from the nitrogen atom-containing (meth)acrylate is 10% by mass, and the more preferred upper limit is 90% by mass, and even more preferred lower limit is 15% by mass, and even more preferred upper limit is 85% by mass.

[0016] The preferred lower limit of the content of the structural units derived from the aromatic group-containing (meth)acrylate in a total of 100 parts by mass of the structural units derived from the aromatic group-containing (meth)acrylate and the structural units derived from the nitrogen atom-containing (meth)acrylate is 5 parts by mass, and the preferred upper limit is 95 parts by mass. When the content of the structural units derived from the aromatic group-containing (meth)acrylate is within the above range, the compound (C1) and the vinyl monomer polymer having the structural units derived from the compound (C1) have better compatibility with the urethane polymer described below, so that the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. The more preferred lower limit of the content of the structural units derived from the aromatic group-containing (meth)acrylate is 10 parts by mass, and the more preferred upper limit is 90 parts by mass, and even more preferred lower limit is 15 parts by mass, and even more preferred upper limit is 85 parts by mass.

[0017] The vinyl monomer polymer preferably further contains a structural unit derived from a hydroxyl group-containing (meth)acrylate. The presence of a structural unit derived from a hydroxyl group-containing (meth)acrylate in the vinyl monomer polymer facilitates crosslinking between the compound (C1) and the vinyl monomer polymer having a structural unit derived from the compound (C1) and the urethane polymer described below using a crosslinking agent described below. As a result, the pressure-sensitive adhesive is further cured and the breaking strength is further improved, thereby further improving the reworkability of the pressure-sensitive adhesive tape of the present invention. In this specification, a structural unit derived from a (meth)acrylate containing an aromatic group and a hydroxyl group is referred to as a structural unit derived from an aromatic group-containing (meth)acrylate. In this specification, a structural unit derived from a (meth)acrylate containing a nitrogen atom and a hydroxyl group is referred to as a structural unit derived from a nitrogen atom-containing (meth)acrylate.

[0018] Examples of the hydroxyl group-containing (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and tetrahydroxyfurfuryl (meth)acrylate.

[0019] The preferred lower limit of the content of the structural units derived from the hydroxyl group-containing (meth)acrylate in the entire vinyl monomer polymer is 0.01% by mass, and the preferred upper limit is 20% by mass. When the content of the structural units derived from the hydroxyl group-containing (meth)acrylate is 0.01% by mass or more, the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the content of the structural units derived from the hydroxyl group-containing (meth)acrylate is 20% by mass or less, the pressure-sensitive adhesive does not become too hard, and the pressure-sensitive adhesive tape of the present invention can exhibit higher adhesive strength. The more preferred lower limit of the content of the structural units derived from the hydroxyl group-containing (meth)acrylate is 0.1% by mass, and the more preferred upper limit is 10% by mass, and the even more preferred lower limit is 0.5% by mass, and the even more preferred upper limit is 5.0% by mass.

[0020] The vinyl monomer polymer may further contain a structural unit derived from an alkyl (meth)acrylate.

[0021] Examples of the alkyl (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, n-heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, isostearyl acrylate, arachidyl (meth)acrylate, etc. Among these, from the viewpoint of compatibility with the urethane polymer described below, alkyl (meth)acrylates with short alkyl chain lengths are preferred, and specifically n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred.

[0022] The vinyl monomer polymer may further have a structural unit derived from a monomer other than the structural unit derived from the aromatic group-containing (meth)acrylate, the structural unit derived from the nitrogen atom-containing (meth)acrylate, the structural unit derived from the hydroxyl group-containing (meth)acrylate, and the structural unit derived from the alkyl (meth)acrylate.

[0023] When the vinyl monomer polymer has structural units derived from (b), the weight-average molecular weight (Mw) of the polymer having structural units derived from an aromatic group-containing (meth)acrylate and structural units derived from a nitrogen atom-containing (meth)acrylate is preferably 200,000 at minimum and 2,000,000 at maximum. When the weight-average molecular weight of the polymer having structural units derived from an aromatic group-containing (meth)acrylate and structural units derived from a nitrogen atom-containing (meth)acrylate is 200,000 or more, the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the weight-average molecular weight of the polymer having structural units derived from an aromatic group-containing (meth)acrylate and structural units derived from a nitrogen atom-containing (meth)acrylate is 2,000,000 or less, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The weight-average molecular weight of the polymer having structural units derived from an aromatic group-containing (meth)acrylate and structural units derived from a nitrogen atom-containing (meth)acrylate is more preferably 400,000 at minimum and 1,500,000 at maximum, and even more preferably 600,000 at maximum and 1,000,000 at maximum.

[0024] When the vinyl monomer polymer has a structural unit derived from (c), the weight-average molecular weight (Mw) of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is preferably 200,000 at the lower limit and 2,000,000 at the upper limit. When the weight-average molecular weight of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is 200,000 or more, the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the weight-average molecular weight of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is 2,000,000 or less, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The weight-average molecular weight of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is more preferably 400,000 at the lower limit and 1,500,000 at the upper limit, and even more preferably 600,000 at the lower limit and 1,000,000 at the upper limit.

[0025] When the vinyl monomer polymer has a structural unit derived from (c), the weight-average molecular weight (Mw) of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is preferably 200,000 at the lower limit and 2,000,000 at the upper limit. When the weight-average molecular weight of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is 200,000 or more, the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the weight-average molecular weight of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is 2,000,000 or less, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The weight-average molecular weight of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is more preferably 400,000 at the lower limit and 1,500,000 at the upper limit, and even more preferably 600,000 at the lower limit and 1,000,000 at the upper limit.

[0026] In this specification, the weight average molecular weight (Mw) refers to the weight average molecular weight calculated as standard polystyrene by gel permeation chromatography (GPC). Specifically, for example, the measurement can be performed using a Waters 2690 Separations Module as a measuring instrument, a Showa Denko GPC KF-806L column, and tetrahydrofuran as a solvent under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C.

[0027] When the compound (C1) is (b) or (c), the vinyl monomer polymer can be produced, for example, by polymerizing a raw material monomer mixture, such as the aromatic group-containing (meth)acrylate and the nitrogen atom-containing (meth)acrylate, and optionally the hydroxyl group-containing (meth)acrylate, the alkyl (meth)acrylate, and the other monomers, through a radical reaction in the presence of a polymerization initiator. When the compound (C1) is (a), in addition to the method for producing the vinyl monomer polymer by the above-mentioned method, a vinyl monomer polymer can also be obtained by simultaneously obtaining a pressure-sensitive adhesive by applying a mixture of the monomer mixture, a photopolymerization initiator, and the urethane polymer to a release PET film or a substrate using an applicator, sealing the coated surface with a release PET film or placing it in a nitrogen atmosphere to prevent the coated surface from coming into contact with air, and then irradiating it with UV light. The method for polymerizing the monomer mixture can be a conventionally known method, such as solution polymerization (boiling point polymerization or constant temperature polymerization), UV polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, etc. Among these, solution polymerization and UV polymerization are preferred because they result in higher adhesive strength of the resulting pressure-sensitive adhesive tape. When solution polymerization is used as the method for polymerizing the monomer mixture, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, dimethyl sulfoxide, ethanol, acetone, diethyl ether, etc. These reaction solvents may be used alone or in combination of two or more.

[0028] Examples of the polymerization initiator include, in the case of solution polymerization, azo compounds and organic peroxides, and in the case of UV polymerization, photopolymerization initiators such as benzophenone compounds, acetophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds and thioxanthone. Examples of the azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), 1-((1-cyano-1-methylethyl)azo)formamide, 4,4'-azobis(4-cyanovaleric acid), dimethyl-2,2'-azobis(2-methylpropionate), dimethyl-1,1'-azobis(1-cyclohexanecarboxylate), 2,2'-azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl)propionamide), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), 2,2 '-Azobis(N-(2-propenyl)-2-methylpropionamide), 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis(N-cyclohexyl-2-methylpropionamide), 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, 2,2'-azobis(2-(1-(2-hydroxyethyl)-2-imidazolin-2-yl)propane) ) dihydrochloride, 2,2'-azobis(2-(2-imidazolin-2-yl)propane), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N-(2-carboxyethyl)-2-methylpropionamidine) tetrahydrate, 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2'-azobis(2,4,4-trimethylpentane), and the like. These azo compounds may be used alone or in combination of two or more.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, t-butylperoxylaurate, etc. These organic peroxides may be used alone or in combination of two or more. Examples of the photopolymerization initiator include Omnirad 184, Omnirad 369, Omnirad 379, Omnirad 379EG, Omnirad 651, Omnirad 784, Omnirad 819, Omnirad 907, Omnirad 2959, Omnirad TPO (all manufactured by IGM Resins), Omnirad OXE01 (manufactured by BASF), benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.). These photopolymerization initiators may be used alone or in combination of two or more.

[0029] The urethane polymer is a compound obtained by reacting a polyol compound with a polyisocyanate compound. When the polyol compound is a polyol diol having a small number of carbon atoms, a hard segment with high polarity is obtained as a structural unit of the urethane polymer. When the urethane polymer contains the hard segment, the cohesive strength of the resulting urethane polymer is further improved by physical crosslinking via hydrogen bonds, thereby further improving the reworkability of the pressure-sensitive adhesive tape of the present invention. On the other hand, when the polyol compound is a polyol having a large number of carbon atoms, a soft segment with low polarity is obtained as a structural unit of the urethane polymer. When the urethane polymer contains the soft segment, the degree of freedom of deformation of the resulting urethane polymer is further improved, thereby further improving the adhesive strength of the pressure-sensitive adhesive tape of the present invention. In particular, from the viewpoint of excellent compatibility with the compound (C1) and a vinyl monomer polymer having a structural unit derived from the compound (C1), it is preferable that the urethane polymer contain the hard segment.

[0030] The method for producing the urethane polymer is not particularly limited, and it can be obtained, for example, by mixing and stirring a polyol compound and a polyisocyanate compound. The reaction between the polyol compound and the polyisocyanate compound can be carried out by any appropriate method used in the production of urethane polymers. If necessary, this reaction can also be carried out by adding an organic solvent (e.g., ethyl acetate, methyl ethyl ketone, chloroform, etc.) that does not have active hydrogen with which the isocyanate group can react, and a catalyst (e.g., organometallic catalysts such as tin chlorides and organotin compounds, organic bases such as tertiary amine compounds, organic acids such as acetic acid and acrylic acid, etc.).

[0031] Examples of the polyol compound include polyester polyols (e.g., polycondensates of dihydric alcohols and divalent basic acids such as adipic acid, azelaic acid, and sepatic acid), polyether polyols (e.g., those obtained by addition polymerization of ethylene oxide, tetrahydrofuran, and the like), polyacrylate polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols or hydrogenated products thereof, polyisoprene polyols or hydrogenated products thereof, phenolic polyols, epoxy polyols, caprolactone polyols, and polysulfone polyols. Polyol compounds also include copolymer polyols such as polyester-polyether polyols. Among these, it is preferable to include at least one selected from the group consisting of polyether diols, polyester diols, and polycarbonate diols, in order to further improve the polarity of the resulting urethane polymer and to achieve excellent compatibility with the compound (C1) and a vinyl monomer polymer having structural units derived from the compound (C1). Among these, from the viewpoints of cohesive strength and compatibility with the compound (C1) and a vinyl monomer polymer having a structural unit derived from the compound (C1), it is more preferable that the urethane polymer contains one selected from the group consisting of polyester diols and polycarbonate diols, and even more preferable that the urethane polymer contains a polycarbonate diol. That is, it is preferable that the urethane polymer contains at least one selected from the group consisting of a structural unit derived from a polyether diol, a structural unit derived from a polyester diol, and a structural unit derived from a polycarbonate diol. It is also more preferable that the urethane polymer contains at least one selected from the group consisting of a structural unit derived from a polyester diol and a structural unit derived from a polycarbonate diol, and even more preferable that the urethane polymer contains a structural unit derived from a polycarbonate diol. These polyol compounds may be used alone or in combination of two or more.

[0032] Examples of the diol compound used in the synthesis of the polycarbonate diol include the above-mentioned polyol compounds, which have a hydroxyl group with a valence of 2. These diol compounds may be used alone or in combination of two or more.

[0033] The preferred lower limit of the content of the structural units derived from the polycarbonate diol in the urethane polymer is 3% by mass, and the preferred upper limit is 70% by mass. When the content of the structural units derived from the polycarbonate diol is 3% by mass or more, the cohesive strength of the resulting urethane polymer is further improved, and the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the content of the structural units derived from the polycarbonate diol is 70% by mass or less, the degree of freedom in deformation of the resulting urethane polymer is further improved, and as a result, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The more preferred lower limit of the content of the structural units derived from the polycarbonate diol is 5% by mass, and the more preferred upper limit is 60% by mass, and even more preferred lower limit is 7% by mass, and even more preferred upper limit is 50% by mass.

[0034] The preferred lower limit of the content of the polyester diol-derived structural units in the urethane polymer is 3% by mass, and the preferred upper limit is 70% by mass. When the content of the polyester diol-derived structural units is 3% by mass or more, the cohesive strength of the resulting urethane polymer is further improved, and the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the content of the polyester diol-derived structural units is 70% by mass or less, the degree of freedom in deformation of the resulting urethane polymer is further improved, and as a result, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The more preferred lower limit of the content of the polyester diol-derived structural units is 5% by mass, and the more preferred upper limit is 60% by mass, and even more preferred lower limit is 7% by mass, and even more preferred upper limit is 50% by mass.

[0035] The preferred lower limit of the content of the polyether diol-derived structural units in the urethane polymer is 3% by mass, and the preferred upper limit is 70% by mass. When the content of the polyether diol-derived structural units is 3% by mass or more, the cohesive strength of the resulting urethane polymer is further improved, and the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the content of the polyether diol-derived structural units is 70% by mass or less, the degree of freedom in deformation of the resulting urethane polymer is further improved, and as a result, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The more preferred lower limit of the content of the polyether diol-derived structural units is 5% by mass, and the more preferred upper limit is 60% by mass, and even more preferred lower limit is 7% by mass, and even more preferred upper limit is 50% by mass.

[0036] Examples of the urethane polymer having a structural unit derived from the polyether diol include AG8451 (manufactured by Lubrizol Corporation).

[0037] From the viewpoint of the reworkability of the pressure-sensitive adhesive tape of the present invention, the polyol compound may contain an alcohol compound having three or more hydroxyl groups.

[0038] Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, norbornane diisocyanate, transcyclohexane-1,4-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, etc. Furthermore, modified products of the above-mentioned polyisocyanate compounds may also be used as the polyisocyanate compound. Examples of the modified polyisocyanate compounds include biuret-modified polyisocyanate compounds, isocyanurate-modified polyisocyanate compounds, adducts obtained by reacting the polyisocyanate compounds with polyols obtained by addition polymerization of glycerin, trimethylolpropane, or these with alkylene oxides such as propylene oxide or ethylene oxide, and polymethylene polyphenyl polyisocyanate, also known as polymeric MDI. Among these, polyisocyanate compounds containing aromatic groups are preferred from the viewpoints of excellent compatibility with the compound (C1) and vinyl monomer polymers having structural units derived from the compound (C1), high reworkability, and high adhesive strength. Among these, modified diphenylmethane diisocyanate compounds such as diphenylmethane diisocyanate and liquid modified diphenylmethane diisocyanate are more preferred. These polyisocyanate compounds may be used alone or in combination of two or more.

[0039] From the viewpoint of the reworkability of the pressure-sensitive adhesive tape of the present invention, the polyisocyanate compound preferably contains an isocyanate compound having three or more isocyanate groups. The preferred lower limit of the content of the structural units derived from isocyanate compounds having three or more isocyanate groups in the urethane polymer is 0.1% by mass, and the preferred upper limit is 20% by mass. By ensuring that the content of the structural units derived from isocyanate compounds having three or more isocyanate groups falls within the above range, the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. The more preferred lower limit is 0.5% by mass, and the more preferred upper limit is 10% by mass.

[0040] The urethane polymer preferably has a structural unit derived from an aromatic group-containing compound. When the urethane polymer has a structural unit derived from an aromatic group-containing compound, the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. Examples of the aromatic group-containing compound include the above-mentioned polyol compounds containing an aromatic group and the above-mentioned aromatic group-containing polyisocyanate compounds.

[0041] The weight-average molecular weight (Mw) of the urethane polymer preferably has a lower limit of 3,000 and a higher limit of 300,000. When the weight-average molecular weight of the urethane polymer is 3,000 or more, the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the weight-average molecular weight of the urethane polymer is 300,000 or less, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved. The weight-average molecular weight of the urethane polymer more preferably has a lower limit of 5,000 and a higher limit of 250,000, an even more preferred lower limit of 7,000, and a still more preferred upper limit of 200,000.

[0042] The preferred lower limit of the content of the urethane polymer per 100 parts by mass of the total of the vinyl monomer polymer and the urethane polymer is 5 parts by mass, and the preferred upper limit is 90 parts by mass. By having the content of the urethane polymer within the above range, the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. The more preferred lower limit of the content of the urethane polymer is 10 parts by mass, and the more preferred upper limit is 70 parts by mass, and the even more preferred lower limit is 15 parts by mass, and the even more preferred upper limit is 60 parts by mass.

[0043] In this specification, the crosslinked product refers to a product obtained by crosslinking a pressure-sensitive adhesive composition. In the first configuration, the vinyl monomer polymer and the urethane polymer in the crosslinked product are crosslinked by a crosslinking agent. In the second configuration, the vinyl monomer polymer and the urethane polymer in the crosslinked product are preferably crosslinked by a crosslinking agent. Examples of the crosslinking agent include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-type crosslinking agents. Among these, isocyanate-based crosslinking agents are preferred because they can selectively crosslink hydroxyl groups and are easy to control the crosslinked structure.

[0044] Examples of the isocyanate crosslinking agent include Coronate HX and Millionate MR200 (both manufactured by Tosoh Corporation).

[0045] The preferred lower limit of the content of the crosslinking agent in the total of the pressure-sensitive adhesive composition and the crosslinking agent is 0.1% by mass, and the preferred upper limit is 20% by mass. When the content of the crosslinking agent is 0.1% by mass or more, the pressure-sensitive adhesive can be more cured, and the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the content of the crosslinking agent is 20% by mass or less, the pressure-sensitive adhesive does not become too hard, and the pressure-sensitive adhesive tape of the present invention can exhibit higher adhesive strength.

[0046] The pressure-sensitive adhesive may further contain a tackifier resin. When the pressure-sensitive adhesive contains a tackifier resin, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further improved.

[0047] Examples of the tackifying resin include rosin-based resins such as rosin ester-based resins, terpene-based resins such as terpene phenolic resins, and petroleum-based resins. Among these, rosin-based resins and terpene phenolic resins are preferred because they have relatively high polarity and are highly compatible with the vinyl monomer polymers and urethane polymers. These tackifying resins may be used alone or in combination of two or more.

[0048] The rosin ester resin is a resin obtained by esterifying, with an alcohol, a rosin resin containing abietic acid as a main component, a disproportionated rosin resin, a hydrogenated rosin resin, a dimer of a resin acid such as abietic acid (polymerized rosin resin), or the like. The hydroxyl value is adjusted to the above-mentioned range by retaining some of the hydroxyl groups of the alcohol used for esterification without being used in the esterification and remaining in the resin. Examples of the alcohol include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol. Note that a resin obtained by esterifying a rosin resin is called a rosin ester resin, a resin obtained by esterifying a disproportionated rosin resin is called a disproportionated rosin ester resin, a resin obtained by esterifying a hydrogenated rosin resin is called a hydrogenated rosin ester resin, and a resin obtained by esterifying a polymerized rosin resin is called a polymerized rosin ester resin.

[0049] The terpene phenol resin is a resin obtained by polymerizing terpene in the presence of phenol.

[0050] The preferred lower limit of the tackifier resin content in the pressure-sensitive adhesive is 1% by mass, and the preferred upper limit is 60% by mass. When the tackifier resin content is 1% by mass or more, the pressure-sensitive adhesive tape of the present invention can exhibit higher adhesive strength. When the tackifier resin content is 60% by mass or less, the adhesive strength of the pressure-sensitive adhesive tape of the present invention does not become too high, and reworkability is further improved. The more preferred lower limit of the tackifier resin content is 3% by mass, and the more preferred upper limit is 50% by mass, and even more preferred lower limit is 5% by mass, and even more preferred upper limit is 40% by mass.

[0051] The pressure-sensitive adhesive may further contain additives such as a silane coupling agent, a plasticizer, a softener, a filler, a pigment, a dye, etc., as needed, within the range that does not impair the effects of the present invention.

[0052] The method for producing the pressure-sensitive adhesive is not particularly limited, and it can be produced by a conventionally known method, etc. Specifically, for example, it can be produced by adding a urethane polymer, a vinyl monomer polymer, or the above-mentioned compound (C1), a crosslinking agent, etc. to a solvent and then thoroughly stirring. Furthermore, when the above-mentioned compound (C1) is the above-mentioned (a), the above-mentioned monomer mixture, the above-mentioned photopolymerization initiator, and the above-mentioned urethane polymer are mixed, and the mixture is applied to a release PET film or a substrate using an applicator. The upper surface of the coated surface is sealed with a release PET film or placed under a nitrogen atmosphere to prevent the coated surface from coming into contact with air, and then the pressure-sensitive adhesive can be obtained by polymerization by UV irradiation.

[0053] In the first configuration, the preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 50 μm. In the first configuration, when the thickness of the pressure-sensitive adhesive layer is 50 μm or more, the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. The more preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 60 μm, and even more preferred lower limit is 70 μm. In the second configuration, the lower limit of the thickness of the pressure-sensitive adhesive layer is 50 μm. In the second configuration, when the thickness of the pressure-sensitive adhesive layer is 50 μm or more, the reworkability of the pressure-sensitive adhesive tape of the present invention is improved. The preferred lower limit of the thickness of the pressure-sensitive adhesive layer is 60 μm, and more preferred lower limit is 70 μm.

[0054] The upper limit of the thickness of the pressure-sensitive adhesive layer is preferably 300 μm. When the thickness of the pressure-sensitive adhesive layer is 300 μm or less, the adhesive strength of the pressure-sensitive adhesive tape of the present invention is further increased. The upper limit of the thickness of the pressure-sensitive adhesive layer is more preferably 250 μm, and even more preferably 200 μm.

[0055] In the first configuration, the preferred lower limit of the tensile stress at break of the pressure-sensitive adhesive layer at 23°C is 0.50 MPa. In the first configuration, the tensile stress at break of the pressure-sensitive adhesive layer at 23°C is 0.50 MPa or more, thereby providing the pressure-sensitive adhesive tape with excellent reworkability. In the first configuration, the more preferred lower limit of the tensile stress at break of the pressure-sensitive adhesive layer at 23°C is 0.60 MPa, and even more preferred is 0.70 MPa. In the second configuration, the lower limit of the tensile stress at break of the pressure-sensitive adhesive layer at 23°C is 0.50 MPa. In the second configuration, the tensile stress at break of the pressure-sensitive adhesive layer at 23°C is 0.50 MPa or more, thereby providing the pressure-sensitive adhesive tape with excellent reworkability. In the second configuration, the preferred lower limit of the tensile stress at break of the pressure-sensitive adhesive layer at 23°C is 0.60 MPa, and even more preferred is 0.70 MPa.

[0056] Furthermore, the upper limit of the tensile stress at break of the pressure-sensitive adhesive layer at 23° C. is preferably 20 MPa. When the tensile stress at break of the pressure-sensitive adhesive layer at 23° C. is 20 MPa or less, the pressure-sensitive adhesive tape of the present invention has higher adhesive strength. The upper limit of the tensile stress at break of the pressure-sensitive adhesive tape of the present invention at 23° C. is more preferably 15 MPa, and even more preferably 10 MPa.

[0057] The preferred lower limit of the breaking elongation percentage of the pressure-sensitive adhesive layer at 23°C is 300%. When the breaking elongation percentage of the pressure-sensitive adhesive layer at 23°C is 300% or more, the pressure-sensitive adhesive tape of the present invention has better reworkability. A more preferred lower limit of the breaking elongation percentage of the pressure-sensitive adhesive layer at 23°C is 350%, and an even more preferred lower limit is 400%. Furthermore, a preferred upper limit of the breaking elongation percentage of the pressure-sensitive adhesive layer is 3000%. When the breaking elongation percentage of the pressure-sensitive adhesive tape of the present invention is 3000% or less, the pressure-sensitive adhesive tape of the present invention has higher adhesive strength. A more preferred upper limit of the breaking elongation percentage of the pressure-sensitive adhesive tape of the present invention is 2500%, and an even more preferred upper limit is 2000%.

[0058] The tensile stress at break and the elongation at break are measured, for example, in accordance with JIS K7161, using a tensile tester (such as "TBS-1225S" manufactured by A&D Co., Ltd.) to perform a tensile test in which the pressure-sensitive adhesive layer is pulled in the long side direction under conditions of 23°C, 50% RH, and a tensile speed of 200 mm / min. The stress at break is the tensile stress, and the ratio of the long side length of the pressure-sensitive adhesive layer when the pressure-sensitive adhesive layer breaks to the long side length of the pressure-sensitive adhesive layer before the tensile test is the elongation at break. The length of the long side of the pressure-sensitive adhesive layer refers to the distance between the chucks of the tensile tester that grip the pressure-sensitive adhesive layer in the tensile test.

[0059] Examples of methods for adjusting the tensile stress at break within the above range include a method of changing the composition of the vinyl monomer polymer or the urethane polymer, a method of changing the type or content of the crosslinking agent, a method of changing the type or content of an additive such as a tackifying resin, etc. Specific examples include a method of increasing the glass transition temperature of the vinyl monomer or the urethane polymer by changing the composition of the vinyl monomer or the urethane polymer.

[0060] Examples of methods for adjusting the breaking elongation percentage within the above range include a method of changing the composition of the vinyl monomer or the urethane polymer, a method of changing the type or content of the crosslinking agent, a method of changing the type or content of an additive such as a tackifying resin, etc. Specific examples include increasing the content of the urethane polymer in the crosslinked product.

[0061] The pressure-sensitive adhesive layer's shear storage modulus at 25°C preferably has a lower limit of 0.05 MPa and a preferred upper limit of 1.0 MPa. When the pressure-sensitive adhesive layer has a shear storage modulus at 25°C of 0.05 MPa or more, the pressure-sensitive adhesive layer becomes hard, and the reworkability of the pressure-sensitive adhesive tape of the present invention is further improved. When the pressure-sensitive adhesive layer has a shear storage modulus at 25°C of 1.0 MPa or less, the pressure-sensitive adhesive tape of the present invention can exhibit higher adhesive strength. The pressure-sensitive adhesive layer's shear storage modulus at 25°C is more preferably 0.07 MPa lower limit, more preferably 0.9 MPa upper limit, even more preferably 0.1 MPa lower limit, and even more preferably 0.8 MPa upper limit.

[0062] The pressure-sensitive adhesive layer preferably has one peak in loss tangent (tan δ) in the temperature range of -10°C to 30°C when measured at a frequency of 1 Hz. When there is one peak in loss tangent (tan δ) in the temperature range of -10°C to 30°C when measured at a frequency of 1 Hz, the pressure-sensitive adhesive layer is more uniform, and therefore the compatibility between the components in the pressure-sensitive adhesive layer is better, so that the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. In this specification, "one peak" means that there is one maximum value of loss tangent (tan δ) in the temperature range of -10°C to 30°C on a spectrum chart of loss tangent (tan δ) obtained by dynamic viscoelasticity measurement.

[0063] When the pressure-sensitive adhesive layer has one loss tangent (tan δ) peak in the temperature range of -10°C to 30°C when measured at a frequency of 1 Hz, the preferred upper limit of the half-width of the loss tangent peak (hereinafter sometimes simply referred to as the "half-width of the loss tangent peak") is 40°C. When the half-width of the loss tangent peak is 40°C or less, the pressure-sensitive adhesive layer is more uniform, and the compatibility between the components of the pressure-sensitive adhesive layer is therefore better, so that the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. A more preferred upper limit of the half-width of the loss tangent peak is 35°C, and an even more preferred upper limit is 30°C. There is no particular preferred lower limit for the half-width of the loss tangent peak, but the lower limit is substantially about 5°C. In this specification, the "half-width of the loss tangent peak" means the full width at half maximum of the loss tangent peak.

[0064] The shear storage modulus at 25°C of the pressure-sensitive adhesive layer, the loss tangent (tan δ) in the temperature range of -10°C to 30°C when measured at a frequency of 1 Hz, and the half-width of the loss tangent (tan δ) peak when measured at a frequency of 1 Hz can be determined by dynamic viscoelasticity measurement. That is, the dynamic viscoelasticity spectrum of the obtained pressure-sensitive adhesive layer is measured using a dynamic viscoelasticity measuring device (e.g., "DVA-200" manufactured by IT Measurement & Control Co., Ltd.) under conditions of a nitrogen atmosphere, a shear direction, a frequency of 1 Hz, a heating rate of 10°C / min, and a temperature range of -50°C to 150°C, thereby obtaining the shear storage modulus at 25°C and the peak of the loss tangent (tan δ) when measured at a frequency of 1 Hz. Furthermore, the half-width of the loss tangent (tan δ) peak can be calculated from the obtained spectrum chart of the loss tangent (tan δ). When the thickness of the pressure-sensitive adhesive layer is less than 500 μm, a pressure-sensitive adhesive layer for measurement is prepared by laminating pressure-sensitive adhesive layers so as to have a thickness of 500 μm or more, and dynamic viscoelasticity is measured.

[0065] Methods for adjusting the shear storage modulus at 25°C of the pressure-sensitive adhesive layer or the half-width of the peak of the loss tangent (tan δ) measured at a frequency of 1 Hz within the above-mentioned ranges include, for example, changing the composition of the vinyl monomer polymer or the urethane polymer, or changing the type and content of the crosslinking agent. Specifically, for example, when the shear storage modulus at 25°C of the pressure-sensitive adhesive layer is reduced, a method can be used in which the proportion of structural units derived from (meth)acrylate monomers having a low glass transition temperature when made into a homopolymer is increased in the vinyl monomer polymer. On the other hand, when the shear storage modulus at 25°C of the pressure-sensitive adhesive layer is increased, a method can be used in which the proportion of structural units derived from (meth)acrylate monomers having a high glass transition temperature when made into a homopolymer is increased in the vinyl monomer polymer. In this specification, the term "glass transition temperature when made into a homopolymer" refers to the glass transition temperature measured by differential scanning calorimetry of a homopolymer in which the (meth)acrylate has a weight-average molecular weight of 100,000 or more and 2,000,000 or less. The glass transition temperature of the homopolymer may 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) in accordance with JIS K6240:2011 at a measurement temperature of -100°C to 200°C and a temperature rise rate of 10°C / min.

[0066] Examples of methods for adjusting the half-value width of the peak of the loss tangent (tan δ) of the pressure-sensitive adhesive layer when measured at a frequency of 1 Hz to fall within the above-mentioned range include a method of changing the composition of the vinyl monomer polymer or the urethane polymer, and a method of changing the type or content of the crosslinking agent.

[0067] The preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 30% by mass, and the preferred upper limit is 99% by mass. A gel fraction of the pressure-sensitive adhesive layer of 30% by mass or more hardens the pressure-sensitive adhesive layer, further improving the reworkability of the pressure-sensitive adhesive tape of the present invention. A gel fraction of the pressure-sensitive adhesive layer of 99% by mass or less enables the pressure-sensitive adhesive tape of the present invention to exhibit higher adhesive strength. A more preferred lower limit of the gel fraction of the pressure-sensitive adhesive layer is 32% by mass, a more preferred upper limit is 90% by mass, an even more preferred lower limit is 35% by mass, and an even more preferred upper limit is 80% by mass. The gel fraction of the pressure-sensitive adhesive layer is measured by the following method. First, a pressure-sensitive adhesive tape having the pressure-sensitive adhesive layer is cut into a planar square shape measuring 30 mm in width and 30 mm in length to prepare a test piece. The test piece is immersed in tetrahydrofuran (THF) at 23°C for 24 hours, filtered using a metal mesh, and dried at 110°C for 1 hour. The mass of the dried test piece is measured, and the gel fraction is calculated using the following formula (I). The test piece is not laminated with a release film for protecting the pressure-sensitive adhesive layer. ０ = 0 to calculate the gel fraction. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １ -W ０ ) (I) (W ０ : Mass of the substrate, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0068] Examples of methods for adjusting the gel fraction of the pressure-sensitive adhesive layer within the above-mentioned range include changing the composition of the vinyl monomer polymer or the urethane polymer, changing the type or content of the crosslinking agent, and changing the type or content of additives such as tackifying resins.

[0069] The preferred lower limit of the Young's modulus of the pressure-sensitive adhesive layer at 23°C is 0.010 MPa, and the preferred upper limit is 10 MPa. When the Young's modulus of the pressure-sensitive adhesive layer at 23°C is 0.010 MPa or more, a greater tensile stress is applied to the pressure-sensitive adhesive tape of the present invention when it is peeled off, thereby further improving the reworkability of the pressure-sensitive adhesive tape of the present invention. When the Young's modulus of the pressure-sensitive adhesive layer at 23°C is 10 MPa or less, the pressure-sensitive adhesive layer does not become too hard, and the pressure-sensitive adhesive tape of the present invention has higher adhesive strength. The more preferred lower limit of the Young's modulus of the pressure-sensitive adhesive layer at 23°C is 0.012 MPa, and the more preferred upper limit is 7 MPa, and the even more preferred lower limit is 0.014 MPa, and the even more preferred upper limit is 5 MPa. The Young's modulus of the pressure-sensitive adhesive layer can be measured, for example, by the following method. That is, by performing a tensile test on the pressure-sensitive adhesive layer to measure the above-mentioned tensile stress at break and elongation at break, the Young's modulus of the pressure-sensitive adhesive layer can be obtained by calculating the slope in the linear region (elastic region) of the obtained stress-strain curve (S-S curve).

[0070] Examples of methods for adjusting the Young's modulus at 23°C of the pressure-sensitive adhesive layer to fall within the above-mentioned range include changing the composition of the vinyl monomer polymer or the urethane polymer, changing the type or content of the crosslinking agent, and changing the type or content of additives such as tackifying resins.

[0071] The pressure-sensitive adhesive tape of the present invention may be a non-support type pressure-sensitive adhesive tape that does not have a substrate, or may be a supported type pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is formed on a substrate. When the pressure-sensitive adhesive tape of the present invention has a substrate, it is sufficient that the pressure-sensitive adhesive layer is on at least one side of the substrate, that is, the pressure-sensitive adhesive tape may be a single-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive layer is on one side of the substrate, or a double-sided pressure-sensitive adhesive tape in which the pressure-sensitive adhesive layers are on both sides of the substrate.

[0072] When the pressure-sensitive adhesive tape of the present invention has a substrate, the substrate is not particularly limited, and examples thereof include resin sheets and resin films made of resins such as acrylic, olefin, polycarbonate, vinyl chloride, ABS, polyethylene terephthalate (PET), nylon, urethane, and polyimide, sheets and films having a mesh structure, and perforated sheets and films (foam sheets and foam films). Among these, from the viewpoint of achieving excellent stress relaxation properties and step conformability, it is preferable that the substrate comprises a foam substrate such as a foam sheet or foam film. By using the pressure-sensitive adhesive, a pressure-sensitive adhesive tape with excellent reworkability can be obtained, even when a foam substrate such as a foam sheet that is prone to break during rework is used as the substrate.

[0073] The thickness of the substrate is preferably 5 μm at the lower limit and 1000 μm at the upper limit. When the thickness of the substrate is within this range, the pressure-sensitive adhesive tape has adequate stiffness and excellent handleability. The thickness of the substrate is more preferably 10 μm at the lower limit, 500 μm at the upper limit, 200 μm at the upper limit, and 150 μm at the upper limit.

[0074] The method for producing the pressure-sensitive adhesive tape of the present invention is not particularly limited, and the tape can be produced by a conventionally known production method. For example, in the case of a double-sided pressure-sensitive adhesive tape having a substrate, the following method can be used. First, a vinyl monomer polymer, a urethane polymer, and a crosslinking agent, and optionally a tackifying resin, etc., are added and thoroughly stirred to obtain a solution of pressure-sensitive adhesive (a). The obtained pressure-sensitive adhesive (a) is applied to one side of a substrate, and the solvent in the solution is completely dried and removed to form a pressure-sensitive adhesive layer (a). Next, a release film is superimposed on the formed pressure-sensitive adhesive layer (a) with its release-treated surface facing the pressure-sensitive adhesive layer (a). Note that when the compound (C1) is the above (a), the above-mentioned monomer mixture, the above-mentioned photopolymerization initiator, the above-mentioned urethane polymer, and optionally a crosslinking agent, etc., may be mixed and applied to a release PET film using an applicator. The coated surface may be sealed with a release PET film or placed in a nitrogen atmosphere to prevent the coated surface from contacting the air, and then polymerized by UV irradiation to form a pressure-sensitive adhesive layer while obtaining the pressure-sensitive adhesive. Next, a release film separate from the above-mentioned release film is prepared, and a solution of adhesive b prepared in the same manner as above is applied to the release-treated surface of this release film. The solvent in the solution is completely dried and removed to produce a laminate film in which adhesive layer b is formed on the surface of the release film. The obtained laminate film is superimposed on the other surface of a substrate having adhesive layer a formed on one surface, with adhesive layer b facing the other surface, to produce a laminate. Then, by pressing the laminate with a rubber roller or the like, a double-sided adhesive tape can be obtained in which adhesive layers are formed on both sides of the substrate and the surfaces of the adhesive layers are covered with release films.

[0075] 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 and in which the surfaces of the pressure-sensitive adhesive layers are covered with release films.

[0076] In the first aspect, the preferred lower limit of the 180° peel strength of the pressure-sensitive adhesive tape of the present invention from SUS at a peel rate of 300 mm / min at 23° C. is 5.0 N / inch, and the preferred upper limit is 30.0 N / inch. When the 180° peel strength of the pressure-sensitive adhesive tape of the present invention from SUS at a peel rate of 300 mm / min at 23° C. is within the above range, the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. The more preferred lower limit of the 180° peel strength of the pressure-sensitive adhesive tape of the present invention from SUS at a peel rate of 300 mm / min at 23° C. is 7.0 N / inch, and the more preferred upper limit is 25.0 N / inch, and the even more preferred lower limit is 10.0 N / inch, and the even more preferred upper limit is 20.0 N / inch. In the second configuration, the lower limit of the 180° peel strength of the pressure-sensitive adhesive tape of the present invention from SUS at a peel rate of 300 mm / min at 23° C. is 5.0 N / inch, and the upper limit is 30.0 N / inch. When the 180° peel strength of the pressure-sensitive adhesive tape of the present invention from SUS at a peel rate of 300 mm / min at 23° C. is within the above range, the pressure-sensitive adhesive tape of the present invention can achieve both higher adhesive strength and better reworkability. The lower limit of the 180° peel strength of the pressure-sensitive adhesive tape of the present invention from SUS at a peel rate of 300 mm / min at 23° C. is preferably 7.0 N / inch, and the upper limit is preferably 25.0 N / inch, more preferably 10.0 N / inch, and more preferably 20.0 N / inch. The 180° peel strength against SUS at 23°C and a peel rate of 300 mm / min can be measured, for example, in accordance with JIS Z0237, using a tensile tester (such as "RTI-1310" manufactured by A&D Co., Ltd.) to perform a peel test at 23°C, 50% RH, a peel rate of 300 mm / min, and a peel angle of 180°. When the pressure-sensitive adhesive tape of the present invention is a non-support type pressure-sensitive adhesive tape that does not have a substrate, or when the pressure-sensitive adhesive tape of the present invention is a double-sided pressure-sensitive adhesive tape that has a substrate, a test piece is prepared in which the side of the pressure-sensitive adhesive tape on which the 180° peel strength is not measured is backed with a PET film or the like, and the peel test is carried out using the prepared test piece.

[0077] Methods for adjusting the 180° peel force from SUS at 23°C and a peel rate of 300 mm / min within the above-mentioned range include, for example, changing the composition of the vinyl monomer polymer or the urethane polymer, changing the type or amount of the crosslinking agent, changing the type or amount of an additive such as a tackifying resin, and increasing the glass transition temperature of the pressure-sensitive adhesive within a range of 25°C or less.

[0078] The use of the pressure-sensitive adhesive tape of the present invention is not particularly limited, but it is preferably used for fixing electronic components or on-vehicle components. Specifically, the pressure-sensitive adhesive tape of the present invention can be suitably used for fixing electronic components in large portable electronic devices, fixing on-vehicle components (for example, on-vehicle panels), etc.

[0079] The present invention also includes a pressure-sensitive adhesive composition containing a vinyl monomer polymer and a urethane polymer, wherein the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from the following (a), (b), or (c): (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate The pressure-sensitive adhesive composition of the present invention can exhibit both high adhesive strength and excellent reworkability.

[0080] In the pressure-sensitive adhesive composition of the present invention, the vinyl monomer polymer has a structural unit derived from a compound (C1) selected from the following (a), (b), or (c): (a) an aromatic group-containing (meth)acrylate and a nitrogen atom-containing (meth)acrylate; (b) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a structural unit derived from a nitrogen atom-containing (meth)acrylate; (c) a polymer having a structural unit derived from an aromatic group-containing (meth)acrylate and a polymer having a structural unit derived from a nitrogen atom-containing (meth)acrylate. The compound (C1) has excellent compatibility with urethane polymers, so that in the pressure-sensitive adhesive composition of the present invention, the vinyl monomer polymer has a structural unit derived from the compound (C1) selected from the above (a), (b), or (c), thereby achieving excellent compatibility with the urethane polymer described below. As a result, crosslinking between the compound (C1) and the vinyl monomer polymer having a structural unit derived from the compound (C1) and the urethane polymer described below proceeds uniformly. As a result, the crosslinked product contained in the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention has a vinyl monomer polymer structure and a urethane polymer structure, and the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention can achieve both high adhesive strength and excellent reworkability. Furthermore, the excellent compatibility between the compound (C1) and the urethane polymer makes it possible to suppress interface formation due to microphase separation in the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention, making it less susceptible to resin rupture when stretched, resulting in excellent reworkability.

[0081] In the pressure-sensitive adhesive composition of the present invention, examples of the aromatic group-containing (meth)acrylate include benzyl acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol acrylate, methylphenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-([1,1'-biphenyl]-2-yloxy)ethyl (meth)acrylate, etc. Of these, from the viewpoint of adhesive properties, phenoxyethyl (meth)acrylate and phenoxydiethylene glycol acrylate are preferred.

[0082] In the pressure-sensitive adhesive composition of the present invention, the content of the structural units derived from the aromatic group-containing (meth)acrylate in the entire vinyl monomer polymer is preferably 5% by mass at the lower limit and 95% by mass at the upper limit. When the content of the structural units derived from the aromatic group-containing (meth)acrylate is 5% by mass or more, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention becomes harder, thereby improving reworkability. When the content of the structural units derived from the aromatic group-containing (meth)acrylate is 95% by mass or less, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention does not become too hard and can exhibit higher adhesive strength. The content of the structural units derived from the aromatic group-containing (meth)acrylate is more preferably 10% by mass at the lower limit and more preferably 90% by mass at the upper limit, even more preferably 15% by mass at the lower limit and even more preferably 85% by mass at the upper limit.

[0083] In the pressure-sensitive adhesive composition of the present invention, examples of the nitrogen atom-containing (meth)acrylate include urethane bond-containing (meth)acrylate, imide bond-containing (meth)acrylate, (meth)acrylamide, etc. Among these, from the viewpoint of achieving better compatibility with the urethane polymer described below, the nitrogen atom-containing (meth)acrylate preferably includes at least one selected from the group consisting of urethane bond-containing (meth)acrylate and imide bond-containing (meth)acrylate, and more preferably includes a urethane bond-containing (meth)acrylate.

[0084] Examples of the urethane bond-containing (meth)acrylate include 1,2-ethanediol 1-acrylate 2-(N-butylcarbamate), etc. Examples of the imide bond-containing (meth)acrylate include N-[2-(acryloyloxy)ethyl]phthalimide, etc.

[0085] In the pressure-sensitive adhesive composition of the present invention, the content of the structural units derived from the nitrogen-atom-containing (meth)acrylate in the entire vinyl monomer polymer is preferably 5% by mass at the lower limit and 95% by mass at the upper limit. When the content of the structural units derived from the nitrogen-atom-containing (meth)acrylate is 5% by mass or more, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention becomes harder, thereby improving reworkability. When the content of the structural units derived from the nitrogen-atom-containing (meth)acrylate is 95% by mass or less, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention does not become too hard and can exhibit higher adhesive strength. The content of the structural units derived from the nitrogen-atom-containing (meth)acrylate is more preferably 10% by mass at the lower limit and 90% by mass at the upper limit, even more preferably 15% by mass at the lower limit and 85% by mass at the upper limit.

[0086] In the pressure-sensitive adhesive composition of the present invention, the content of the structural units derived from the aromatic group-containing (meth)acrylate, based on a total of 100 parts by mass of the structural units derived from the aromatic group-containing (meth)acrylate and the structural units derived from the nitrogen atom-containing (meth)acrylate, is preferably 5 parts by mass at the lower limit and 95 parts by mass at the upper limit. When the content of the structural units derived from the aromatic group-containing (meth)acrylate is within the above range, the compound (C1) and the vinyl monomer polymer having the structural units derived from the compound (C1) have better compatibility with the urethane polymer described below, so that the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention can achieve both higher adhesive strength and better reworkability. The content of the structural units derived from the aromatic group-containing (meth)acrylate is more preferably 10 parts by mass at the lower limit and 90 parts by mass at the upper limit, and even more preferably 15 parts by mass at the lower limit and 85 parts by mass at the upper limit.

[0087] In the pressure-sensitive adhesive composition of the present invention, the vinyl monomer polymer preferably further contains a structural unit derived from a hydroxyl group-containing (meth)acrylate. When the vinyl monomer polymer contains a structural unit derived from a hydroxyl group-containing (meth)acrylate, crosslinking between the compound (C1) and the urethane polymer described below by a crosslinking agent described below is more likely to proceed. As a result, the pressure-sensitive adhesive composition of the present invention is more cured, resulting in improved breaking strength and improved reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention. In this specification, a structural unit derived from a (meth)acrylate containing an aromatic group and a hydroxyl group is referred to as a structural unit derived from an aromatic group-containing (meth)acrylate. In this specification, a structural unit derived from a (meth)acrylate containing a nitrogen atom and a hydroxyl group is referred to as a structural unit derived from a nitrogen atom-containing (meth)acrylate.

[0088] Examples of the hydroxyl group-containing (meth)acrylate in the pressure-sensitive adhesive composition of the present invention include 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and tetrahydroxyfurfuryl (meth)acrylate.

[0089] In the pressure-sensitive adhesive composition of the present invention, the content of the structural units derived from the hydroxyl group-containing (meth)acrylate in the entire vinyl monomer polymer is preferably 0.01% by mass at the lower limit and 20% by mass at the upper limit. When the content of the structural units derived from the hydroxyl group-containing (meth)acrylate is 0.01% by mass or more, the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. When the content of the structural units derived from the hydroxyl group-containing (meth)acrylate is 20% by mass or less, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is not too hard, and the pressure-sensitive adhesive can exhibit higher adhesive strength. The content of the structural units derived from the hydroxyl group-containing (meth)acrylate is more preferably 0.1% by mass at the lower limit and 10% by mass at the upper limit, and even more preferably 0.5% by mass at the lower limit and 5.0% by mass at the upper limit.

[0090] In the pressure-sensitive adhesive composition of the present invention, the vinyl monomer polymer may further have a structural unit derived from an alkyl(meth)acrylate.

[0091] Examples of the alkyl (meth)acrylate in the pressure-sensitive adhesive composition of the present invention include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, n-heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, isostearyl acrylate, arachidyl (meth)acrylate, etc. Among these, from the viewpoint of compatibility with the urethane polymer described below, alkyl (meth)acrylates with short alkyl chain lengths are preferred, and specifically n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred.

[0092] The vinyl monomer polymer in the pressure-sensitive adhesive composition of the present invention may further have a structural unit derived from a monomer other than the structural unit derived from the aromatic group-containing (meth)acrylate, the structural unit derived from the nitrogen atom-containing (meth)acrylate, the structural unit derived from the hydroxyl group-containing (meth)acrylate, and the structural unit derived from the alkyl (meth)acrylate.

[0093] In the pressure-sensitive adhesive composition of the present invention, when the vinyl monomer polymer has structural units derived from (b), the weight-average molecular weight (Mw) of the polymer having structural units derived from the aromatic group-containing (meth)acrylate and structural units derived from the nitrogen atom-containing (meth)acrylate is preferably 200,000 at the lower limit and 2,000,000 at the upper limit. When the weight-average molecular weight of the polymer having structural units derived from the aromatic group-containing (meth)acrylate and structural units derived from the nitrogen atom-containing (meth)acrylate is 200,000 or more, the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. When the weight-average molecular weight of the polymer having structural units derived from the aromatic group-containing (meth)acrylate and structural units derived from the nitrogen atom-containing (meth)acrylate is 2,000,000 or less, the adhesive strength of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. The weight average molecular weight of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate and a structural unit derived from the nitrogen atom-containing (meth)acrylate is more preferably 400,000 in lower limit and 1,500,000 in upper limit, still more preferably 600,000 in lower limit and 1,000,000 in upper limit.

[0094] In the pressure-sensitive adhesive composition of the present invention, when the vinyl monomer polymer has a structural unit derived from (c), the weight-average molecular weight (Mw) of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is preferably 200,000 at the lower limit and 2,000,000 at the upper limit. When the weight-average molecular weight of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is 200,000 or more, the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. When the weight-average molecular weight of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is 2,000,000 or less, the adhesive strength of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. The weight-average molecular weight of the polymer having a structural unit derived from the aromatic group-containing (meth)acrylate is more preferably 400,000 at the lower limit and 1,500,000 at the upper limit, and even more preferably 600,000 at the lower limit and 1,000,000 at the upper limit.

[0095] In the pressure-sensitive adhesive composition of the present invention, when the vinyl monomer polymer has a structural unit derived from (c), the weight-average molecular weight (Mw) of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is preferably 200,000 at the lower limit and 2,000,000 at the upper limit. When the weight-average molecular weight of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is 200,000 or more, the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. When the weight-average molecular weight of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is 2,000,000 or less, the adhesive strength of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. The weight-average molecular weight of the polymer having a structural unit derived from the nitrogen-atom-containing (meth)acrylate is more preferably 400,000 at the lower limit and 1,500,000 at the upper limit, and even more preferably 600,000 at the lower limit and 1,000,000 at the upper limit.

[0096] When the compound (C1) in the pressure-sensitive adhesive composition of the present invention is (b) or (c), the vinyl monomer polymer can be produced, for example, by polymerizing a monomer mixture, which serves as raw materials for the aromatic group-containing (meth)acrylate and the nitrogen atom-containing (meth)acrylate, and optionally the hydroxyl group-containing (meth)acrylate, the alkyl (meth)acrylate, and the other monomers, through a radical reaction in the presence of a polymerization initiator. The monomer mixture can be polymerized using conventional methods, such as 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 higher adhesive strength for the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention. When solution polymerization is used as the method for polymerizing the monomer mixture, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, dimethyl sulfoxide, ethanol, acetone, and diethyl ether. These reaction solvents may be used alone or in combination of two or more.

[0097] Examples of the polymerization initiator include, in the case of solution polymerization, azo compounds and organic peroxides, and in the case of UV polymerization, photopolymerization initiators such as benzophenone compounds, acetophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds and thioxanthone. Examples of the azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), 1-((1-cyano-1-methylethyl)azo)formamide, 4,4'-azobis(4-cyanovaleric acid), dimethyl-2,2'-azobis(2-methylpropionate), dimethyl-1,1'-azobis(1-cyclohexanecarboxylate), 2,2'-azobis(2-methyl-N-(1,1'-bis(hydroxymethyl)-2-hydroxyethyl)propionamide), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), 2,2 '-Azobis(N-(2-propenyl)-2-methylpropionamide), 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis(N-cyclohexyl-2-methylpropionamide), 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, 2,2'-azobis(2-(1-(2-hydroxyethyl)-2-imidazolin-2-yl)propane) ) dihydrochloride, 2,2'-azobis(2-(2-imidazolin-2-yl)propane), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N-(2-carboxyethyl)-2-methylpropionamidine) tetrahydrate, 2,2'-azobis(1-imino-1-pyrrolidino-2-methylpropane) dihydrochloride, 2,2'-azobis(2,4,4-trimethylpentane), and the like. These azo compounds may be used alone or in combination of two or more.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, t-butylperoxylaurate, etc. These organic peroxides may be used alone or in combination of two or more. Examples of the photopolymerization initiator include Omnirad 184, Omnirad 369, Omnirad 379, Omnirad 379EG, Omnirad 651, Omnirad 784, Omnirad 819, Omnirad 907, Omnirad 2959, Omnirad TPO (all manufactured by IGM Resins), Omnirad OXE01 (manufactured by BASF), benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether (all manufactured by Tokyo Chemical Industry Co., Ltd.). These photopolymerization initiators may be used alone or in combination of two or more.

[0098] In the pressure-sensitive adhesive composition of the present invention, the urethane polymer is a compound obtained by reacting a polyol compound with a polyisocyanate compound. When the polyol compound is a polyol diol having a low carbon number, a hard segment with high polarity is obtained as a structural unit of the urethane polymer. When the urethane polymer contains the hard segment, the cohesive strength of the resulting urethane polymer is further improved by physical crosslinking via hydrogen bonds, and the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. On the other hand, when the polyol compound is a polyol having a high carbon number, a soft segment with low polarity is obtained as a structural unit of the urethane polymer. When the urethane polymer contains the soft segment, the degree of freedom of deformation of the resulting urethane polymer is further improved, and as a result, the adhesive strength of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. In particular, from the viewpoint of excellent compatibility with the compound (C1) and a vinyl monomer polymer having a structural unit derived from the compound (C1), it is preferable that the urethane polymer contain the hard segment.

[0099] The method for producing the urethane polymer in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and can be, for example, obtained by mixing and stirring a polyol compound and a polyisocyanate compound. The reaction between the polyol compound and the polyisocyanate compound can be carried out by any appropriate method used in the production of urethane polymers. If necessary, this reaction can also be carried out by adding an organic solvent (e.g., ethyl acetate, methyl ethyl ketone, chloroform, etc.) that does not have active hydrogen with which the isocyanate group can react, and a catalyst (e.g., organometallic catalysts such as tin chlorides and organotin compounds, organic bases such as tertiary amine compounds, organic acids such as acetic acid and acrylic acid, etc.).

[0100] Examples of the polyol compound in the pressure-sensitive adhesive composition of the present invention include polyester polyols (e.g., polycondensates of dihydric alcohols and divalent basic acids such as adipic acid, azelaic acid, and sepatic acid), polyether polyols (e.g., those obtained by addition polymerization of ethylene oxide, tetrahydrofuran, and the like), polyacrylate polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols or hydrogenated products thereof, polyisoprene polyols or hydrogenated products thereof, phenolic polyols, epoxy polyols, caprolactone polyols, and polysulfone polyols. Polyol compounds also include copolymer polyols such as polyester-polyether polyols. Among these, it is preferable to include at least one selected from the group consisting of polyether diols, polyester diols, and polycarbonate diols, in order to further improve the polarity of the resulting urethane polymer and to achieve excellent compatibility with the compound (C1) and a vinyl monomer polymer having structural units derived from the compound (C1). Among these, from the viewpoints of cohesive strength and compatibility with the compound (C1) and a vinyl monomer polymer having a structural unit derived from the compound (C1), it is more preferable that the urethane polymer contains one selected from the group consisting of polyester diols and polycarbonate diols, and even more preferable that the urethane polymer contains a polycarbonate diol. That is, it is preferable that the urethane polymer contains at least one selected from the group consisting of a structural unit derived from a polyether diol, a structural unit derived from a polyester diol, and a structural unit derived from a polycarbonate diol. It is also more preferable that the urethane polymer contains at least one selected from the group consisting of a structural unit derived from a polyester diol and a structural unit derived from a polycarbonate diol, and even more preferable that the urethane polymer contains a structural unit derived from a polycarbonate diol. These polyol compounds may be used alone or in combination of two or more.

[0101] In the pressure-sensitive adhesive composition of the present invention, examples of the diol compound used in synthesizing the polycarbonate diol include the above-mentioned polyol compounds, and those in which the hydroxyl group has a valence of 2. These diol compounds may be used alone or in combination of two or more.

[0102] In the pressure-sensitive adhesive composition of the present invention, the preferred lower limit of the content of the structural units derived from the polycarbonate diol in the urethane polymer is 3% by mass, and the preferred upper limit is 70% by mass. When the content of the structural units derived from the polycarbonate diol is 3% by mass or more, the cohesive strength of the resulting urethane polymer is further improved, and the reworkability of the PSA obtained from the pressure-sensitive adhesive composition of the present invention is further improved. When the content of the structural units derived from the polycarbonate diol is 70% by mass or less, the degree of freedom in deformation of the resulting urethane polymer is further improved, and as a result, the adhesive strength of the PSA obtained from the pressure-sensitive adhesive composition of the present invention is further improved. A more preferred lower limit of the content of the structural units derived from the polycarbonate diol is 5% by mass, a more preferred upper limit is 60% by mass, an even more preferred lower limit is 7% by mass, and an even more preferred upper limit is 50% by mass.

[0103] The preferred lower limit of the content of the polyester diol-derived structural units in the urethane polymer is 3% by mass, and the preferred upper limit is 70% by mass. When the content of the polyester diol-derived structural units is 3% by mass or more, the cohesive strength of the resulting urethane polymer is further improved, and the reworkability of the PSA obtained from the PSA composition of the present invention is further improved. When the content of the polyester diol-derived structural units is 70% by mass or less, the degree of freedom in deformation of the resulting urethane polymer is further improved, and as a result, the adhesive strength of the PSA obtained from the PSA composition of the present invention is further improved. The more preferred lower limit of the content of the polyester diol-derived structural units is 5% by mass, and the more preferred upper limit is 60% by mass, and even more preferred lower limit is 7% by mass, and even more preferred upper limit is 50% by mass.

[0104] In the pressure-sensitive adhesive composition of the present invention, the preferred lower limit of the content of the polyether diol-derived structural units in the urethane polymer is 3% by mass, and the preferred upper limit is 70% by mass. When the content of the polyether diol-derived structural units is 3% by mass or more, the cohesive strength of the resulting urethane polymer is further improved, and the reworkability of the PSA obtained from the pressure-sensitive adhesive composition of the present invention is further improved. When the content of the polyether diol-derived structural units is 70% by mass or less, the degree of freedom in deformation of the resulting urethane polymer is further improved, and as a result, the adhesive strength of the PSA obtained from the pressure-sensitive adhesive composition of the present invention is further improved. A more preferred lower limit of the content of the polyether diol-derived structural units is 5% by mass, a more preferred upper limit is 60% by mass, an even more preferred lower limit is 7% by mass, and an even more preferred upper limit is 50% by mass.

[0105] In the pressure-sensitive adhesive composition of the present invention, examples of the urethane polymer having a structural unit derived from the polyether diol include AG8451 (manufactured by Lubrizol Corporation).

[0106] From the viewpoint of the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention, the polyol compound may contain an alcohol compound having three or more hydroxyl groups.

[0107] Examples of the polyisocyanate compound in the pressure-sensitive adhesive composition of the present invention include diphenylmethane diisocyanate, tolylene diisocyanate, naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, norbornane diisocyanate, transcyclohexane-1,4-diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, cyclohexane diisocyanate, bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane diisocyanate, etc. Furthermore, modified products of the above-mentioned polyisocyanate compounds may also be used as the polyisocyanate compound. Examples of modified polyisocyanate compounds include biuret-modified polyisocyanate compounds, isocyanurate-modified polyisocyanate compounds, adducts obtained by reacting the polyisocyanate compounds with polyols obtained by addition polymerization of glycerin, trimethylolpropane, or these with alkylene oxides such as propylene oxide or ethylene oxide, and polymethylene polyphenyl polyisocyanate, also known as polymeric MDI. Among these, polyisocyanate compounds containing aromatic groups are preferred from the viewpoints of excellent compatibility with the above-mentioned compound (C1) and vinyl monomer polymers having structural units derived from the above-mentioned compound (C1), high reworkability, and high adhesive strength. Among these, modified diphenylmethane diisocyanate compounds such as diphenylmethane diisocyanate and liquid modified diphenylmethane diisocyanate are more preferred. These polyisocyanate compounds may be used alone or in combination of two or more.

[0108] In the pressure-sensitive adhesive composition of the present invention, from the viewpoint of the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention, the polyisocyanate compound preferably contains an isocyanate compound having three or more isocyanate groups. In the pressure-sensitive adhesive composition of the present invention, the content of the structural units derived from the isocyanate compound having three or more isocyanate groups in the urethane polymer is preferably 0.1% by mass at the lower limit and 20% by mass at the upper limit. By having the content of the structural units derived from the isocyanate compound having three or more isocyanate groups within the above range, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention can achieve both higher adhesive strength and better reworkability. The lower limit is more preferably 0.5% by mass at the lower limit and the upper limit is more preferably 10% by mass at the upper limit.

[0109] In the pressure-sensitive adhesive composition of the present invention, the urethane polymer preferably has a structural unit derived from an aromatic group-containing compound. When the urethane polymer has a structural unit derived from an aromatic group-containing compound, the reworkability of the pressure-sensitive adhesive of the present invention is further improved. Examples of the aromatic group-containing compound include the above-mentioned polyol compounds containing an aromatic group and the above-mentioned polyisocyanate compounds containing an aromatic group.

[0110] In the pressure-sensitive adhesive composition of the present invention, the weight-average molecular weight (Mw) of the urethane polymer preferably has a lower limit of 3,000 and a higher limit of 300,000. When the weight-average molecular weight of the urethane polymer is 3,000 or more, the reworkability of the pressure-sensitive adhesive of the present invention is further improved. When the weight-average molecular weight of the urethane polymer is 300,000 or less, the adhesive strength of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. The weight-average molecular weight of the urethane polymer more preferably has a lower limit of 5,000 and a higher limit of 250,000, an even more preferred lower limit of 7,000, and a still more preferred upper limit of 200,000.

[0111] In the pressure-sensitive adhesive composition of the present invention, the content of the urethane polymer is preferably 5 parts by mass or less, and preferably 90 parts by mass or less, per 100 parts by mass of the total of the vinyl monomer polymer and the urethane polymer. By having the content of the urethane polymer within the above range, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention can achieve both higher adhesive strength and better reworkability. The content of the urethane polymer is more preferably 10 parts by mass or less, and more preferably 70 parts by mass or less, and even more preferably 15 parts by mass or less, and even more preferably 60 parts by mass or less.

[0112] In the pressure-sensitive adhesive composition of the present invention, when the urethane polymer and the vinyl monomer polymer in the crosslinked product are crosslinked with a crosslinking agent, examples of the crosslinking agent include an isocyanate-based crosslinking agent, an aziridine-based crosslinking agent, an epoxy-based crosslinking agent, a metal chelate-based crosslinking agent, etc. Among these, an isocyanate-based crosslinking agent is preferred because it can selectively crosslink hydroxyl groups and is easy to control the crosslinked structure.

[0113] Examples of the isocyanate crosslinking agent include Coronate HX and Millionate MR200 (both manufactured by Tosoh Corporation).

[0114] In the pressure-sensitive adhesive composition of the present invention, the preferred lower limit of the content of the crosslinking agent in the total of the pressure-sensitive adhesive composition and the crosslinker is 0.1 mass%, and the preferred upper limit is 20 mass%. When the content of the crosslinking agent is 0.1 mass% or more, the pressure-sensitive adhesive can be more cured, and the reworkability of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention is further improved. When the content of the crosslinking agent is 20 mass% or less, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition of the present invention does not become too hard, and the pressure-sensitive adhesive tape of the present invention can exhibit higher adhesive strength.

[0115] The pressure-sensitive adhesive composition of the present invention may further contain a tackifier resin. When the pressure-sensitive adhesive composition of the present invention contains a tackifier resin, the adhesive strength is further improved.

[0116] Examples of the tackifier resin in the pressure-sensitive adhesive composition of the present invention include rosin-based resins such as rosin ester-based resins, terpene-based resins such as terpene phenolic resins, and petroleum-based resins. Among these, rosin-based resins and terpene phenolic resins are preferred because they have relatively high polarity and excellent compatibility with the vinyl monomer polymer and the urethane polymer. These tackifier resins may be used alone or in combination of two or more.

[0117] The rosin ester resin in the pressure-sensitive adhesive composition of the present invention is a resin obtained by esterifying, with an alcohol, a rosin resin containing abietic acid as a main component, a disproportionated rosin resin, a hydrogenated rosin resin, a dimer of a resin acid such as abietic acid (polymerized rosin resin), or the like. The hydroxyl value is adjusted to the above-mentioned range by retaining some of the hydroxyl groups of the alcohol used for esterification in the resin without being used in the esterification. Examples of the alcohol include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol. Note that a resin obtained by esterifying a rosin resin is called a rosin ester resin, a resin obtained by esterifying a disproportionated rosin resin is called a disproportionated rosin ester resin, a resin obtained by esterifying a hydrogenated rosin resin is called a hydrogenated rosin ester resin, and a resin obtained by esterifying a polymerized rosin resin is called a polymerized rosin ester resin.

[0118] The terpene phenol resin in the pressure-sensitive adhesive composition of the present invention is a resin obtained by polymerizing a terpene in the presence of phenol.

[0119] In the pressure-sensitive adhesive composition of the present invention, the preferred lower limit of the tackifier resin content in the pressure-sensitive adhesive composition of the present invention is 1% by mass, and the preferred upper limit is 60% by mass. When the tackifier resin content is 1% by mass or more, the PSA obtained from the pressure-sensitive adhesive composition of the present invention can exhibit higher adhesive strength. When the tackifier resin content is 60% by mass or less, the PSA obtained from the pressure-sensitive adhesive composition of the present invention does not have too high adhesive strength, and the reworkability of the PSA obtained from the pressure-sensitive adhesive composition of the present invention is further improved. A more preferred lower limit of the tackifier resin content is 3% by mass, a more preferred upper limit is 50% by mass, an even more preferred lower limit is 5% by mass, and an even more preferred upper limit is 40% by mass.

[0120] The pressure-sensitive adhesive composition of the present invention may further contain additives such as a silane coupling agent, a plasticizer, a softener, a filler, a pigment, a dye, etc., as necessary, within the range that does not impair the effects of the present invention.

[0121] A pressure-sensitive adhesive comprising the crosslinked product of the vinyl monomer polymer and the urethane polymer in the pressure-sensitive adhesive composition of the present invention also constitutes one aspect of the present invention. When the pressure-sensitive adhesive of the present invention comprises the crosslinked product of the urethane polymer and the vinyl monomer polymer in the pressure-sensitive adhesive composition, the urethane polymer structure of the crosslinked product provides the pressure-sensitive adhesive of the present invention with excellent reworkability, while the vinyl monomer polymer structure of the crosslinked product provides the pressure-sensitive adhesive of the present invention with high adhesive strength. Furthermore, since the crosslinked product has a structure in which the vinyl monomer polymer structure and the urethane polymer structure are crosslinked, the pressure-sensitive adhesive becomes hard and has improved reworkability. In other words, by including the crosslinked product, the pressure-sensitive adhesive of the present invention can achieve both high adhesive strength and excellent reworkability. In the crosslinked product of the vinyl monomer polymer and the urethane polymer in the pressure-sensitive adhesive composition, the vinyl monomer polymer and the urethane polymer may be crosslinked with a crosslinking agent or a polymerization initiator. However, from the viewpoint of achieving better adhesion to the adherend, it is preferable that the vinyl monomer polymer and the urethane polymer are crosslinked with a crosslinking agent.

[0122] The method for producing the pressure-sensitive adhesive is not particularly limited, and it can be produced by a conventionally known method. Specifically, for example, a pressure-sensitive adhesive composition can be produced by adding a crosslinking agent to a solvent containing a urethane polymer, a vinyl monomer polymer, or the compound (C1), and, if necessary, a tackifier resin, and the like, and then thoroughly stirring the mixture. Furthermore, when the compound (C1) is the above (a), the above-mentioned monomer mixture, the above-mentioned photopolymerization initiator, and the above-mentioned urethane polymer can be mixed and applied to a release PET film or substrate using an applicator. The upper surface of the coated film can be sealed with a release PET film or placed under a nitrogen atmosphere to prevent the coated surface from coming into contact with air, and then polymerized by UV irradiation to obtain a pressure-sensitive adhesive.

[0123] According to the present invention, a pressure-sensitive adhesive tape that exhibits both high adhesive strength and excellent reworkability can be provided. Also, according to the present invention, a pressure-sensitive adhesive composition that can exhibit both high adhesive strength and excellent reworkability can be provided. Furthermore, according to the present invention, a pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition can be provided.

[0124] The following examples further illustrate aspects of the present invention, but the present invention is not limited to these examples.

[0125] (Production of Urethane Polymer) (Production of Polycarbonate-Based Polyurethane U1) 100 parts by mass of polycarbonate diol (Kuraray Co., Ltd., "Kuraraypolyol C-1090") as a polyol compound and 0.01 parts by mass of dibutyltin dilaurate were placed in a 500 mL separable flask. The contents of the flask were stirred and mixed under vacuum (20 mmHg or less) at 100°C for 30 minutes. The pressure was then returned to normal pressure, and 19 parts by mass of diphenylmethane diisocyanate (Nisso Shoji Co., Ltd., "Pure MDI") as a polyisocyanate compound was added. The mixture was stirred and reacted at 80°C for 3 hours to obtain polycarbonate-based polyurethane U1. The weight-average molecular weight of the resulting polycarbonate-based polyurethane U1 was 17,000.

[0126] (Production of Polycarbonate-Based Polyurethane U2) Polycarbonate-based polyurethane U2 was obtained in the same manner as polycarbonate-based polyurethane U1, except that diphenylmethane diisocyanate (manufactured by Nisso Shoji Co., Ltd., "Pure MDI") was used in an amount of 23.5 parts by mass. The weight-average molecular weight of the obtained polycarbonate-based polyurethane U2 was 70,000.

[0127] (Production of Polyester-Based Polyurethane U3) Polyester-based polyurethane U3 was obtained in the same manner as polycarbonate-based polyurethane U1, except that 100 parts by mass of polyester diol (manufactured by Ube Industries, Ltd., "Etanacol 3010") was used as the polyol compound. The weight average molecular weight of the obtained polyester-based polyurethane U3 was 17,000.

[0128] (Production of Polyether-Based Polyurethane U4) Polyether-based polyurethane U4 was obtained in the same manner as polycarbonate-based polyurethane U1, except that 100 parts by mass of polyether diol (manufactured by Hodogaya Chemical Co., Ltd., "PTC-L3500") was used as the polyol compound. The weight-average molecular weight of the obtained polyether-based polyurethane U4 was 17,000.

[0129] (Examples 1-1 to 1-13, 1-18 to 1-25, 2-1 to 2-6, 2-9 to 2-15, Comparative Examples 1 to 2, 14 to 17) (Production of Pressure-Sensitive Adhesives and Pressure-Sensitive Adhesive Tapes) The monomers constituting acrylic copolymers A to E and H to M shown in Table 1, and the urethane polymers and polymerization initiators shown in Tables 2 to 5 were mixed to prepare pressure-sensitive adhesive compositions. After adding the crosslinking agents shown in Tables 2 to 5 to the obtained pressure-sensitive adhesive compositions, the obtained pressure-sensitive adhesive compositions were applied to the release-treated surface of a release PET film using an applicator, and the release-treated surface of a release PET film (manufactured by Nippa Corporation, "1-E", thickness 50 μm) was placed on top of the coated surface so that it faced the coated surface, thereby sealing the film. The obtained coated products were cured using a batch-type UV LED curing device (manufactured by ITEC Corporation, "M UVBA") at a wavelength of 365 nm and an illuminance of 20 mW / cm. ２ UV rays with a wavelength of 405 nm and an illuminance of 40 mW / cm ２ of ultraviolet light, with a total irradiation dose of 900 mJ / cm ２ As a result, a pressure-sensitive adhesive containing a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure, and a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive and having the thickness shown in Tables 2 to 5 were formed, and the obtained pressure-sensitive adhesive layer was used as a pressure-sensitive adhesive tape.

[0130] (Examples 1-14 to 1-15, 2-7 to 2-8, Comparative Examples 3 to 13, 18) (Production of Acrylic Copolymers A, F, G, H, I, and N) Ethyl acetate was added as a polymerization solvent to a reaction vessel, and the atmosphere was replaced with nitrogen. 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 the monomer mixture shown in Table 1 was added dropwise over 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 solutions containing acrylic copolymers A, F, G, H, I, and N.

[0131] (Preparation of Pressure-Sensitive Adhesives and Pressure-Sensitive Adhesive Tapes) A ​​urethane polymer shown in Tables 2 to 5 was added to the resulting solution containing acrylic copolymers A, F, G, H, I, and N to obtain a solution containing a pressure-sensitive adhesive composition. Furthermore, a crosslinking agent shown in Tables 2 to 5 was added to the solution containing the pressure-sensitive adhesive composition, followed by thorough stirring to prepare a pressure-sensitive adhesive solution containing a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure. The resulting pressure-sensitive adhesive solution was coated onto a 50 μm-thick release PET film so that the thickness after drying would be 100 μm, and then dried at 110° C. for 5 minutes to form a pressure-sensitive adhesive layer. Furthermore, a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer was obtained by overlaying the release-treated surface of a 38 μm-thick release PET film so that it faced the formed pressure-sensitive adhesive layer.

[0132] (Examples 1-16 to 1-17) (Production of adhesive and adhesive tape) The release PET film was peeled off from one side of an adhesive layer having the same composition and thickness as in Example 2, exposing it. The exposed adhesive layer was attached to one side of the substrate shown in Table 3. Furthermore, a similar adhesive layer was attached to the other side of the substrate shown in Table 3 in the same manner, thereby obtaining a substrate and a double-sided adhesive tape having adhesive layers on both sides of the substrate.

[0133] (Gel fraction of pressure-sensitive adhesive layer) Each pressure-sensitive adhesive tape obtained in the Examples and Comparative Examples was cut into a flat rectangular shape of 30 mm width x 30 mm length, and then the release PET film was peeled off to prepare a test piece. The prepared test piece was immersed in tetrahydrofuran (THF) at 23°C for 24 hours, filtered using a metal mesh, and dried at 110°C for 1 hour. The mass of the test piece after drying was measured, and the gel fraction of the pressure-sensitive adhesive layer was calculated using the following formula (I). The results are shown in Tables 2 to 5. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １ -W ０ ) (I) (W ０ : Mass of the substrate, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0134] (Young's modulus of pressure-sensitive adhesive layer at 23°C) Each pressure-sensitive adhesive layer obtained in the Examples and Comparative Examples was punched out with a No. 4 dumbbell to obtain a sample, and a tensile test was carried out at 23°C and 50% RH using a tensile tester (manufactured by A&D Co., Ltd., "STB-1225S") at a tensile speed of 200 mm / min (chuck distance 50 mm) to measure the Young's modulus (%) of the pressure-sensitive adhesive layer at 23°C. The results are shown in Tables 2 to 5.

[0135] (Shear storage modulus of pressure-sensitive adhesive layer at 25°C) Each of the pressure-sensitive adhesive layers obtained in the Examples and Comparative Examples was laminated to a thickness of 500 µm to prepare a pressure-sensitive adhesive layer for measurement, and a test specimen was obtained. The dynamic viscoelasticity spectrum of the obtained test specimen was measured using a dynamic viscoelasticity measuring device (manufactured by IT Measurement & Control Co., Ltd., "DVA-200") under conditions of a nitrogen atmosphere, shear direction, frequency of 1 Hz, heating rate of 10°C / min, and temperature range of -50°C to 150°C, to obtain the shear storage modulus (MPa) at 25°C. The results are shown in Tables 2 to 5.

[0136] (Peak temperature of loss tangent (tan δ) and half-width of the loss tangent (tan δ) peak in the temperature range of -10°C to 30°C when measured at a frequency of 1 Hz on the pressure-sensitive adhesive layer) From the spectrum chart of loss tangent (tan δ) obtained by measuring the "(shear storage modulus of the pressure-sensitive adhesive layer at 25°C)" described above, the peak temperature (°C) of the loss tangent (tan δ) and half-width of the loss tangent (tan δ) peak in the temperature range of -10°C to 30°C were obtained. Note that for Comparative Examples 3 to 13 in which the peak temperature (°C) of the loss tangent was not -10°C to 30°C, the half-width of the loss tangent (tan δ) peak was not calculated. The results are shown in Tables 2 to 5.

[0137] (180° Peel Force of Pressure-Sensitive Adhesive Tape from SUS at a Peeling Speed ​​of 300 mm / min at 23°C) Each of the pressure-sensitive adhesive tapes obtained in the Examples and Comparative Examples was cut into a flat rectangular shape measuring 25 mm wide and 80 mm long. The release PET film on one side (the side not to be measured) of the cut pressure-sensitive adhesive tape was peeled off, and then a test specimen was backed with a 50 μm-thick PET film (Cosmoshine A4100, manufactured by Toyobo Co., Ltd.). The release PET film on the other side (the side to be measured) of the prepared test specimen was peeled off, and the specimen was bonded to a SUS plate (a SUS304 plate that had been washed with ethanol and then wiped dry) by rolling it back and forth once at a speed of 10 mm / min using a 2 kg rubber roller. The specimen was then aged for 24 hours at 23°C and 50% RH to obtain a measurement sample. The obtained measurement samples were subjected to a peel test in accordance with JIS Z0237 using a tensile tester ("RTI-1310" manufactured by A&D Co., Ltd.) at 23°C, 50% RH, a peel rate of 300 mm / min, and a peel angle of 180° to obtain the 180° peel strength (N / inch) of the pressure-sensitive adhesive tape against SUS at a peel rate of 300 mm / min at 23°C. The results are shown in Tables 2 to 5.

[0138] (Tensile stress at break of pressure-sensitive adhesive layer at 23°C and elongation at break of pressure-sensitive adhesive layer at 23°C) Each pressure-sensitive adhesive tape obtained in the Examples and Comparative Examples was punched out with a No. 4 dumbbell (manufactured by Kobunshi Keiki Co., Ltd.) to obtain a sample of the pressure-sensitive adhesive layer. A tensile test was performed by pulling the sample in the long side direction of the pressure-sensitive adhesive layer at a pulling speed of 200 mm / min (chuck distance of 50 mm) using a tensile tester (manufactured by A&D Co., Ltd., "STB-1225S") at 23°C and 50% RH. The stress at which the pressure-sensitive adhesive layer broke was defined as the tensile stress at break (MPa), and the ratio of the long side length of the pressure-sensitive adhesive layer sample at break to the long side length of the pressure-sensitive adhesive layer sample before the tensile test was defined as the elongation at break (%). The results are shown in Tables 2 to 5. The length of the long side of the pressure-sensitive adhesive layer refers to the distance between the chucks of the tensile tester that grips the pressure-sensitive adhesive layer sample in the tensile test. For Examples 1-16 and 1-17 having a substrate, a tensile test was carried out using a sample of the pressure-sensitive adhesive layer obtained by punching out the pressure-sensitive adhesive layer with a No. 4 dumbbell before laminating it on the substrate.

[0139] <Evaluation> The pressure-sensitive adhesives and pressure-sensitive adhesive tapes obtained in the examples and comparative examples were evaluated by the following methods. The results are shown in Tables 2 to 5.

[0140] (Transparency of Pressure-Sensitive Adhesive) The transparency of the obtained pressure-sensitive adhesive was visually observed and evaluated according to the following criteria: ◯: The pressure-sensitive adhesive was transparent. Δ: The pressure-sensitive adhesive was slightly cloudy. ×: The pressure-sensitive adhesive was cloudy.

[0141] (Reworkability of Adhesive Tape) (1) Reworkability of Adhesive Tape at a Peel Angle of 30° The obtained adhesive tape was cut into a size of 10 mm wide x 80 mm long, one release PET film was peeled off, and the tape was applied to a SUS plate (a SUS304 plate washed with ethanol and then wiped dry). The tape was then pressed against the plate by reciprocating a 2 kg rubber roller at a speed of 10 mm / min. The tape was then left to stand for 24 hours in an environment of 23°C and 50% RH to prepare a test sample. Next, the other release PET film of the adhesive tape in the test sample was peeled off to expose the adhesive layer. The edge of the adhesive layer was pulled at an angle of 30° from the horizontal at a speed of 300 mm / min and peeled off from the SUS plate. The reworkability of the adhesive tape was evaluated three times per sample and based on the following criteria: ◯: The adhesive tape was peeled cleanly without breaking during all three tests. △: The adhesive tape was peeled cleanly without breaking during two tests, but broke during one test. ×: The adhesive tape was peeled cleanly without breaking less than two times. Note that for Comparative Examples 17 and 18, the reworkability of the adhesive tape was not evaluated because the measurement results of the above-mentioned "(180° peel force of adhesive tape from SUS at a peel rate of 300 mm / min at 23°C)" showed that the adhesive tapes had no adhesive strength.

[0142] (2) Reworkability of Pressure-Sensitive Adhesive Tape at a Peel Angle of 0° Further evaluation of the reworkability of the pressure-sensitive adhesive tape was carried out using the same method and criteria as in "(1) Reworkability of Pressure-Sensitive Adhesive Tape at a Peel Angle of 30°" above, except that the peel angle was changed from 30° from the horizontal to 0° from the horizontal.

[0143] Usually, adhesive tapes without a substrate or adhesive tapes with a substrate having sufficient elasticity, such as a foam substrate, tend to break as the peel angle increases due to stress concentration at the peel point. Therefore, adhesive tapes other than those of Example 1-17, which are adhesive tapes without a substrate or adhesive tapes having a foam substrate as a substrate, are considered to have sufficient reworkability if they are rated as "○" or "△" in the evaluation of "(2) Reworkability of Adhesive Tape at a Peel Angle of 0°" above, even if they are rated as "×" in the evaluation of "(1) Reworkability of Adhesive Tape at a Peel Angle of 30°" above. Furthermore, the better the evaluation in the evaluation of "(1) Reworkability of Adhesive Tape at a Peel Angle of 30°" above, the more excellent the reworkability of the adhesive tape. On the other hand, adhesive tapes with a substrate having poor elasticity, such as a resin film, tend to have a higher peel force as the peel angle decreases, since the adhesive layer is less likely to deform. Therefore, if the pressure-sensitive adhesive tape of Example 1-17, which is a pressure-sensitive adhesive tape having a resin film as a substrate, is rated as "○" or "△" in the evaluation of the above-mentioned "(1) Reworkability of pressure-sensitive adhesive tape at a peel angle of 30°", then the pressure-sensitive adhesive tape will have sufficient reworkability even if it is rated as "×" in the evaluation of the above-mentioned "(2) Reworkability of pressure-sensitive adhesive tape at a peel angle of 0°". Furthermore, the better the evaluation in the evaluation of the above-mentioned "(1) Reworkability of pressure-sensitive adhesive tape at a peel angle of 30°", the more excellent the reworkability of the pressure-sensitive adhesive tape.

[0144] The symbols of the monomers shown in Table 1 represent the following: BA: n-butyl acrylate 2-EHA: 2-ethylhexyl acrylate Aac: acrylic acid HEA: 2-hydroxyethyl acrylate 4-HBA: 4-hydroxybutyl acrylate IBOA: isobornyl acrylate BzA: benzyl acrylate

[0145]

[0146]

[0147]

[0148]

[0149]

[0150] According to the present invention, a pressure-sensitive adhesive tape that exhibits both high adhesive strength and excellent reworkability can be provided. Also, according to the present invention, a pressure-sensitive adhesive composition that can exhibit both high adhesive strength and excellent reworkability can be provided. Furthermore, according to the present invention, a pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition can be provided.

Claims

1. Having an adhesive layer containing an adhesive, The configuration satisfies at least one configuration selected from the group consisting of the first configuration and the second configuration described below. An adhesive tape characterized by the following features. First configuration: The adhesive contains a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure. In the aforementioned crosslinked product, the vinyl monomer polymer and the urethane polymer are crosslinked with a crosslinking agent. The vinyl monomer polymer has constituent units derived from a compound (C1) selected from (a), (b), or (c) below. (a) Aromatic group-containing (meth)acrylates and nitrogen atom-containing (meth)acrylates (b) Polymers having constituent units derived from aromatic group-containing (meth)acrylates and constituent units derived from nitrogen atom-containing (meth)acrylates (c) Polymers having structural units derived from aromatic group-containing (meth)acrylates and polymers having structural units derived from nitrogen atom-containing (meth)acrylates Second configuration: The thickness of the adhesive layer is 50 μm or more. The tensile breaking stress of the adhesive layer at 23°C is 0.50 MPa or higher. The 180° peel force of the adhesive tape against SUS at a peeling speed of 300 mm / min at 23°C is 5.0 N / inch or more and 30.0 N / inch or less.

2. The adhesive layer has one peak in the loss tangent (tanδ) in the temperature range of -10°C to 30°C when measured at a frequency of 1 Hz, and the full width at half maximum of the loss tangent peak is 40°C or less. The shear storage modulus (G') of the adhesive layer at 25°C is 1.0 MPa or less. The adhesive tape according to claim 1.

3. In the first configuration described above, the thickness of the adhesive layer is 50 μm or more. The tensile breaking stress of the adhesive layer at 23°C is 0.50 MPa or higher. The 180° peel force of the adhesive tape against SUS at a peeling speed of 300 mm / min at 23°C is 5.0 N / inch or more and 30.0 N / inch or less. The adhesive tape according to claim 1 or 2.

4. In the second configuration described above, the adhesive contains a crosslinked product having a vinyl monomer polymer structure and a urethane polymer structure. In the aforementioned crosslinked product, the vinyl monomer polymer and the urethane polymer are crosslinked with a crosslinking agent. The adhesive tape according to claim 1 or 2, wherein the vinyl monomer polymer has constituent units derived from a compound (C1) selected from (a), (b), or (c) below. (a) Aromatic group-containing (meth)acrylates and nitrogen atom-containing (meth)acrylates (b) Polymers having constituent units derived from aromatic group-containing (meth)acrylates and constituent units derived from nitrogen atom-containing (meth)acrylates (c) Polymers having structural units derived from aromatic group-containing (meth)acrylates and polymers having structural units derived from nitrogen atom-containing (meth)acrylates

5. The adhesive tape according to claim 1 or 2, wherein the nitrogen atom-containing (meth)acrylate comprises at least one selected from the group consisting of urethane bond-containing (meth)acrylate and imide bond-containing (meth)acrylate.

6. The adhesive tape according to claim 5, wherein the nitrogen atom-containing (meth)acrylate includes a urethane bond-containing (meth)acrylate.

7. The adhesive tape according to claim 1 or 2, wherein the content of the constituent units derived from the aromatic group-containing (meth)acrylate in a total of 100 parts by mass of the constituent units derived from the aromatic group-containing (meth)acrylate and the constituent units derived from the nitrogen atom-containing (meth)acrylate is 5 parts by mass or more and 95 parts by mass or less.

8. The adhesive tape according to claim 1 or 2, wherein the vinyl monomer polymer further comprises structural units derived from hydroxyl group-containing (meth)acrylate.

9. The adhesive tape according to claim 1 or 2, wherein the vinyl monomer polymer further comprises structural units derived from alkyl (meth)acrylate.

10. The adhesive tape according to claim 1 or 2, wherein the urethane polymer has at least one selected from the group consisting of structural units derived from polyether diol, structural units derived from polyester diol, and structural units derived from polycarbonate diol.

11. The adhesive tape according to claim 10, wherein the urethane polymer has at least one selected from the group consisting of constituent units derived from polyester diol and constituent units derived from polycarbonate diol.

12. The adhesive tape according to claim 11, wherein the urethane polymer has constituent units derived from polycarbonate diol.

13. The adhesive tape according to claim 1 or 2, wherein the urethane polymer has constituent units derived from an aromatic group-containing compound.

14. The adhesive tape according to claim 1 or 2, wherein the content of the urethane polymer in a total of 100 parts by mass of the vinyl monomer polymer and the urethane polymer is 5 parts by mass or more and 90 parts by mass or less.

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

16. The adhesive tape according to claim 1 or 2, wherein the elongation rate at break of the adhesive layer at 23°C is 300% or more.

17. The adhesive tape according to claim 1 or 2, wherein the gel fraction of the adhesive layer is 30% by mass or more and 99% by mass or less.

18. The adhesive tape according to claim 1 or 2, wherein the Young's modulus of the adhesive layer at 23°C is 0.010 MPa or more and 10 MPa or less.

19. The adhesive tape according to claim 1 or 2, having a base material and having the adhesive layer on at least one surface of the base material.

20. The adhesive tape according to claim 19, wherein the base material includes a foam base material.

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

22. It contains vinyl monomer polymer and urethane polymer, The vinyl monomer polymer has constituent units derived from a compound (C1) selected from (a), (b), or (c) below. An adhesive composition characterized by the following features. (a) Aromatic group-containing (meth)acrylates and nitrogen atom-containing (meth)acrylates (b) Polymers having constituent units derived from aromatic group-containing (meth)acrylates and constituent units derived from nitrogen atom-containing (meth)acrylates (c) Polymers having structural units derived from aromatic group-containing (meth)acrylates and polymers having structural units derived from nitrogen atom-containing (meth)acrylates

23. The adhesive composition according to claim 22, wherein the nitrogen atom-containing (meth)acrylate comprises at least one selected from the group consisting of urethane bond-containing (meth)acrylate and imide bond-containing (meth)acrylate.

24. The adhesive composition according to claim 23, wherein the nitrogen atom-containing (meth)acrylate comprises a urethane bond-containing (meth)acrylate.

25. The adhesive composition according to claim 22, 23, or 24, wherein the content of the constituent units derived from the aromatic group-containing (meth)acrylate in a total of 100 parts by mass of the constituent units derived from the aromatic group-containing (meth)acrylate and the constituent units derived from the nitrogen atom-containing (meth)acrylate is 5 parts by mass or more and 95 parts by mass or less.

26. The adhesive composition according to claim 22, 23, or 24, wherein the vinyl monomer polymer further comprises structural units derived from hydroxyl group-containing (meth)acrylate.

27. The adhesive composition according to claim 22, 23, or 24, wherein the vinyl monomer polymer further comprises structural units derived from alkyl (meth)acrylate.

28. The adhesive composition according to claim 22, 23, or 24, wherein the urethane polymer has at least one selected from the group consisting of structural units derived from polyetherdiol, structural units derived from polyesterdiol, and structural units derived from polycarbonatediol.

29. The adhesive composition according to claim 28, wherein the urethane polymer has at least one selected from the group consisting of constituent units derived from polyester diol and constituent units derived from polycarbonate diol.

30. The adhesive composition according to claim 29, wherein the urethane polymer has constituent units derived from polycarbonate diol.

31. The adhesive composition according to claim 22, 23, or 24, wherein the urethane polymer has constituent units derived from an aromatic group-containing compound.

32. The adhesive composition according to claim 22, 23, or 24, wherein the content of the urethane polymer in a total of 100 parts by mass of the vinyl monomer polymer and the urethane polymer is 5 parts by mass or more and 90 parts by mass or less.

33. Furthermore, the adhesive composition according to claim 22, 23, or 24 further contains a tackifying resin.

34. An adhesive comprising a crosslinking product of the vinyl monomer polymer and the urethane polymer in the adhesive composition according to claim 22, 23, or 24.

35. The adhesive according to claim 34, wherein in the crosslinked product, the vinyl monomer polymer and the urethane polymer are crosslinked with a crosslinking agent.