Adhesive sheet, laminated sheet, chemical liquid tank, and method for manufacturing chemical liquid tank

Abstract

The present invention provides an adhesive sheet that has excellent strength of adhesion to a fluororesin such as polytetrafluoroethylene even without a pretreatment on the fluororesin and has excellent workability for lamination. In addition, the purpose of the present invention is to provide: a laminated sheet obtained using the adhesive sheet; and a method for manufacturing a chemical liquid tank using the adhesive sheet. The present invention pertains to an adhesive sheet having an adhesive layer (Y1) on one surface and an adhesive layer (Y2) on the other surface, the adhesive sheet having at least one configuration selected from the group consisting of the following first configuration and second configuration. First configuration: The adhesive layer (Y1) contains a base polymer (P1) and a tackifier resin, the base polymer (P1) includes at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin, and the adhesive layer (Y2) is a hot-melt adhesive layer. The second configuration: The adhesive layer (Y1) has a 180° peel strength of 5.0 N / 25 mm or more with respect to polytetrafluoroethylene at 23°C, and the adhesive layer (Y2) has a probe tack value of 20 N / 5 mmφ or less as measured under the conditions of 23°C, a pressurizing force of 98 gf, a pressurizing speed of 100 mm / sec, a pressurizing time of 10 seconds, and a peeling-off speed of 5 mm / sec.

Description

Adhesive sheet, laminated sheet, chemical tank, and method for manufacturing chemical tank

[0001] The present invention relates to an adhesive sheet. The present invention also relates to a laminated sheet using the adhesive sheet, and a method for producing a chemical liquid tank using the adhesive sheet.

[0002] Adhesive sheets have traditionally been widely used to secure components in electronic devices. Specifically, adhesive sheets are used, for example, to bond a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to bond a touch panel module to a display panel module. Adhesive sheets used to secure such electronic device components are required to have not only high adhesiveness but also properties such as heat resistance, thermal conductivity, and impact resistance depending on the environment of the location where they are used (e.g., Patent Documents 1 to 3).

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

[0004] In recent years, demand for fluororesins has been increasing in various fields due to their excellent heat resistance, chemical resistance, low dielectric properties, and water repellency. For example, ethylene-tetrafluoroethylene copolymer (ETFE) is used in a wide range of fields, such as electrical wire coating materials and building materials, due to its high mechanical strength and excellent processability.

[0005] In the semiconductor and chemical industries, many chemicals, including acids and alkalis, are used. To prevent corrosion during storage and disposal of these chemicals, tank linings with fluororesin attached to the tank body are often used. Conventionally, adhesives such as chloroprene rubber and epoxy resin have been used to attach fluororesin to the tank body. However, these adhesives cannot achieve sufficient adhesive strength unless the fluororesin is pretreated. To improve adhesive strength, the fluororesin is typically pretreated with naphthalene or glass backing. These pretreatments are not only expensive but also pose issues in terms of quality degradation, safety, and environmental pollution. Therefore, there has been a demand for adhesives that can be used without pretreatment.

[0006] Furthermore, if the adhesive used to bond the fluororesin has too strong an adhesive strength to the can body at room temperature, it may become sticky, resulting in poor workability, and problems may arise such that it is difficult to adjust the position where the fluororesin is bonded on the can body. Therefore, it is desirable to use an adhesive that is less sticky and has excellent workability in bonding, making it easy to adjust the position where the fluororesin is bonded on the can body.

[0007] The present invention provides an adhesive sheet that has excellent adhesive strength to fluororesins such as polytetrafluoroethylene without the need for pretreatment of the fluororesins, and that exhibits excellent lamination workability. The present invention also provides a laminated sheet using the adhesive sheet, and a method for manufacturing a chemical liquid tank using the adhesive sheet.

[0008]

[0010] The present disclosure relates to a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (Y1) on one surface and a pressure-sensitive adhesive layer (Y2) on the other surface, the pressure-sensitive adhesive sheet having at least one configuration selected from the group consisting of the following first and second configurations. First configuration: The pressure-sensitive adhesive layer (Y1) contains a base polymer (P1) and a tackifier resin, the base polymer (P1) contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin, and the pressure-sensitive adhesive layer (Y2) is a hot-melt pressure-sensitive adhesive layer. Second configuration: The pressure-sensitive adhesive layer (Y1) has a 180° peel strength from polytetrafluoroethylene at 23°C of 5.0 N / 25 mm or more, and the pressure-sensitive adhesive layer (Y2) has a probe tack value of 20 N / 5 mmφ or less, measured under conditions of 23°C, a pressure of 98 gf, a pressure-applying rate of 100 mm / sec, a pressure-applying time of 10 seconds, and a peel-off rate of 5 mm / sec.

[0013] Disclosure 2 is the adhesive sheet of Disclosure 1, having the first configuration, wherein the adhesive layer (Y1) has a 180° peel strength from polytetrafluoroethylene of 2.5 N / 25 mm or more at 23°C. Disclosure 3 is the adhesive sheet of Disclosure 1, having the second configuration, wherein the adhesive layer (Y1) contains a base polymer (P1) and a tackifier resin, and the base polymer (P1) comprises at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin. Disclosure 4 is the adhesive sheet of Disclosure 1, 2, or 3, wherein the adhesive layer (Y2) has a softening point of 40°C or higher.

[0023] Present Disclosure 5 is the adhesive sheet according to Present Disclosure 1, 2, 3, or 4, wherein the adhesive sheet has a 180° peel strength from SUS at 23°C of 10 N / 25 mm or more when the adhesive layer (Y2) side is pressure-bonded to SUS under a pressure of 0.1 MPa in an environment of 150°C for 10 minutes.

[0023] The present disclosure 6 is the adhesive sheet according to disclosure 1, 2, 3, 4, or 5, wherein the adhesive layer (Y2) contains a base polymer (P2), and the base polymer (P2) comprises at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, an ethylene-vinyl acetate copolymer, a chloroprene rubber, a nitrile rubber, a polyurethane resin, a polyamide resin, a polyolefin resin, a polyester resin, an epoxy resin, and a silicone resin.

[0023] The present disclosure 7 is the adhesive sheet of present disclosure 1, 2, 3, 4, 5, or 6, which has the first configuration or the second configuration, and wherein the adhesive layer (Y1) contains a tackifier resin, the tackifier resin comprising a tackifier resin (T1) having at least one structural unit (A) selected from the group consisting of structural units (A-1), (A-1'), (A-2), (A-2'), (A-3), (A-3'), (A-4), and (A-4') represented by the following formula:

[0024] The present disclosure 8 is the adhesive sheet of present disclosure 7, wherein the tackifier resin (T1) further has a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers.

[0023] The present disclosure 9 is the adhesive sheet according to disclosure 1, 2, 3, 4, 5, 6, 7, or 8, having the first configuration or the second configuration, and wherein the adhesive layer (Y1) contains a tackifier resin, and the tackifier resin comprises at least one tackifier resin (T2) selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum-based resins. The present disclosure 10 is the adhesive sheet according to disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the adhesive layer (Y1) is not a hot-melt adhesive layer. The present disclosure 11 is the adhesive sheet according to disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, wherein the adhesive layer (Y1) has a thickness of 25 µm or more and 1000 µm or less. The present disclosure 12 is the adhesive sheet of the present disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or 11, further comprising a base material layer between the adhesive layer (Y1) and the adhesive layer (Y2).

[0014] Disclosure 13 is the adhesive sheet of Disclosure 12, wherein the substrate layer contains at least one material selected from the group consisting of polyester resin, polyimide resin, polyether resin, polyolefin resin, polyurethane resin, metal, glass fiber, and carbon fiber. Disclosure 14 is the adhesive sheet of Disclosure 12 or 13, wherein the substrate layer is composed of at least one material selected from the group consisting of a nonwoven fabric and a woven fabric. Disclosure 15 is the adhesive sheet of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, which is used for joining a lining sheet to a can body in a chemical tank. Disclosure 16 is the adhesive sheet of Disclosure 15, wherein the chemical tank is a chemical tank for semiconductors or a chemical tank for the chemical industry. Disclosure 17 is a laminate sheet having a sheet containing a fluororesin on the adhesive layer (Y1) side of the adhesive sheet of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16. Disclosure 18 is a liquid chemical tank having attached to the inner surface of a can body the adhesive sheet of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 or the laminate sheet of Disclosure 17. Disclosure 19 is a method for manufacturing a liquid chemical tank, comprising the step of attaching the laminate sheet of Disclosure 17 to the inner surface of a can body of the liquid chemical tank. Disclosure 20 is a method for producing a chemical liquid tank according to Disclosure 19, comprising the steps of: using the adhesive sheet according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, and pressing a sheet containing a fluororesin onto the adhesive layer (Y1) to produce a laminate sheet according to Disclosure 17; and laminating the adhesive layer (Y2) of the laminate sheet to the inside of a can body of a chemical liquid tank. Disclosure 21 is a method for producing a chemical liquid tank according to Disclosure 20, wherein, in the step of laminating the adhesive layer (Y2) of the laminate sheet to the inside of a can body of a chemical liquid tank, the laminate sheet is heated to adhere the adhesive layer (Y2) to the inside of the can body. Disclosure 22 is a method for producing a chemical liquid tank according to Disclosure 19, 20, or 21, wherein the chemical liquid tank is a chemical liquid tank for semiconductors or a chemical liquid tank for the chemical industry.

[0009]

[0010]

[0011]

[0012]

[0013] In the formula, R １ ~R ７ each represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. n and l each represent an integer of 2 or more and 4 or less, and n' and l' each represent an integer of 2 or more and 5 or less. m and k each represent an integer of 1 or more and 4 or less, and m' and k' each represent an integer of 1 or more and 5 or less. * represents a linking moiety. The present invention will be described in detail below.

[0014] The present inventors investigated a configuration in which a pressure-sensitive adhesive sheet having different pressure-sensitive adhesive layers on each of its two surfaces is used, with one pressure-sensitive adhesive layer containing a specific base polymer and the other pressure-sensitive adhesive layer being a hot-melt pressure-sensitive adhesive layer. The present inventors also investigated a configuration in which a pressure-sensitive adhesive sheet having different pressure-sensitive adhesive layers on each of its two surfaces is used, with one pressure-sensitive adhesive layer having a specific 180° peel strength from polytetrafluoroethylene and the other pressure-sensitive adhesive layer having a specific probe tack value at 23°C. As a result, they found that, in each configuration, a pressure-sensitive adhesive sheet can be obtained that has excellent pressure-sensitive adhesive strength to fluororesins such as polytetrafluoroethylene and excellent lamination workability even without pretreatment of the fluororesin, thereby completing the present invention. In this specification, the terms "adhesion" and "adhesion" not only refer to a permanent adhesive phenomenon, but also refer to the temporary adhesive phenomenon of "sticking."

[0015] The adhesive sheet of the present invention has an adhesive layer (Y1) on one surface and an adhesive layer (Y2) on the other surface. The adhesive sheet of the present invention has at least one configuration selected from the group consisting of the following first and second configurations. First configuration: The adhesive layer (Y1) contains a base polymer (P1) and a tackifier resin, the base polymer (P1) contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin, and the adhesive layer (Y2) is a hot-melt adhesive layer. Second configuration: The adhesive layer (Y1) has a 180° peel strength from polytetrafluoroethylene at 23°C of 5.0 N / 25 mm or more, and the adhesive layer (Y2) has a probe tack value of 20 N / 5 mmφ or less, measured under conditions of 23°C, a pressure of 98 gf, a pressure application rate of 100 mm / sec, a pressure application time of 10 seconds, and a peel-off rate of 5 mm / sec. Hereinafter, matters common to the first and second configurations will be described without specifying the configuration in question.

[0016] In the first configuration, the pressure-sensitive adhesive layer (Y1) contains a base polymer (P1). In the first configuration, the base polymer (P1) contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin. In the second configuration, the pressure-sensitive adhesive layer (Y1) preferably contains a base polymer (P1). In the second configuration, the base polymer (P1) preferably contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin. When the base polymer (P1) contains at least one selected from the group consisting of the (meth)acrylic copolymer, the styrene-based elastomer, and the silicone resin, the pressure-sensitive adhesive layer (Y1) has excellent pressure-sensitive adhesive strength to fluororesins. In particular, in view of the wide range of design possibilities for the pressure-sensitive adhesive layer (Y1) and the fact that the pressure-sensitive adhesive layer (Y1) can exhibit strong pressure-sensitive adhesive strength, it is preferable that the base polymer (P1) contains at least one selected from the group consisting of (meth)acrylic copolymers and styrene-based elastomers. In this specification, the "base polymer" refers to a polymer component that contributes to the development of pressure-sensitive adhesive properties of the pressure-sensitive adhesive layer. The tackifying resin described below is not included in the "base polymer".

[0017] The (meth)acrylic copolymer preferably has a structural unit derived from an alkyl (meth)acrylate. The alkyl (meth)acrylate preferably includes an alkyl (meth)acrylate having an alkyl group having 4 to 12 carbon atoms at the ester terminal. That is, the (meth)acrylic copolymer preferably has a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 4 to 12 carbon atoms at the ester terminal. When the (meth)acrylic copolymer has a structural unit derived from an alkyl (meth)acrylate having an alkyl group having 4 to 12 carbon atoms at the ester terminal, the glass transition temperature (Tg) of the (meth)acrylic copolymer is further reduced. As a result, the shear storage modulus at 25°C measured at a frequency of 10 Hz in the dynamic viscoelasticity measurement of the adhesive layer (Y1) described below (hereinafter, sometimes simply referred to as "the shear storage modulus at 25°C of the adhesive layer (Y1)") is appropriately reduced, and the flexibility of the adhesive layer (Y1) is further improved, so that the adhesive strength of the adhesive layer (Y1) to the fluororesin is further improved.

[0018] Examples of the alkyl(meth)acrylate having an alkyl group having from 4 to 12 carbon atoms at the ester terminal include n-butyl(meth)acrylate, tert-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-hexyl(meth)acrylate, n-heptyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, 1-methylheptyl(meth)acrylate, lauryl(meth)acrylate, etc. Among these, the alkyl(meth)acrylate having an alkyl group having from 4 to 12 carbon atoms at the ester terminal preferably includes an alkyl(meth)acrylate having an alkyl group having from 6 to 8 carbon atoms at the ester terminal, since this further improves the adhesive strength (particularly the adhesive strength to fluororesin) of the adhesive sheet to be obtained. These alkyl(meth)acrylates having an alkyl group having 4 to 12 carbon atoms at the ester terminal may be used alone or in combination of two or more kinds.

[0019] The content of the structural units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at the ester terminal in the (meth)acrylic copolymer is preferably 50% by mass or more. When the content of the structural units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at the ester terminal is 50% by mass or more, the glass transition temperature (Tg) of the (meth)acrylic copolymer is further reduced, resulting in an appropriate reduction in the shear storage modulus at 25°C of the adhesive layer described below, and further improvement in the flexibility of the adhesive layer (Y1), thereby further improving the adhesive strength to fluororesins. A more preferred lower limit of the content of the structural units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at the ester terminal is 90% by mass, and an even more preferred lower limit is 95% by mass.

[0063] The upper limit of the constituent units derived from alkyl (meth)acrylate having an alkyl group having from 4 to 12 carbon atoms at the ester terminal may be 99.99 mass%, but from the viewpoint of the cohesive strength of the bulk of the pressure-sensitive adhesive layer (Y1), the upper limit is preferably 99 mass%.

[0020] The content of the structural units derived from alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms at the ester terminal in the (meth)acrylic copolymer is preferably 50% by mass or more. When the content of the structural units derived from alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms at the ester terminal is 50% by mass or more, the glass transition temperature (Tg) of the (meth)acrylic copolymer is further reduced, and as a result, the shear storage modulus at 25°C of the adhesive layer described below is appropriately reduced, further improving the flexibility of the adhesive layer (Y1), and further improving the adhesive strength to fluororesin. A more preferred lower limit of the content of the structural units derived from alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms at the ester terminal is 85% by mass, and an even more preferred lower limit is 90% by mass.

[0044] From the viewpoint of the cohesive strength of the bulk of the pressure-sensitive adhesive layer (Y1), the upper limit of the constituent units derived from an alkyl (meth)acrylate having an alkyl group having from 6 to 8 carbon atoms at the ester terminal is preferably 99.5 mass%, more preferably 99 mass%.

[0021] The alkyl (meth)acrylate may contain alkyl (meth)acrylates other than the alkyl (meth)acrylates having an alkyl group having 4 to 12 carbon atoms at the ester terminal. Examples of the other alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, esters of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)octanol-1 and (meth)acrylic acid, esters of alcohols having a total of 18 carbon atoms and one or two methyl groups in the linear main chain and (meth)acrylic acid, behenyl (meth)acrylate, and arachidyl (meth)acrylate. These other alkyl (meth)acrylates may be used alone, or two or more may be used in combination.

[0022]

[0042] The (meth)acrylic copolymer preferably further comprises a structural unit derived from a polar functional group-containing monomer. When the (meth)acrylic copolymer comprises a structural unit derived from a polar functional group-containing monomer, the cohesive strength of the bulk of the adhesive layer (Y1) increases, and the adhesive strength of the adhesive sheet to be obtained is further improved.

[0023] The polar functional group is reactive for crosslinking reactions and the like, and is preferably at least one selected from the group consisting of a carboxy group, a hydroxyl group, an amino group, and an epoxy group. Among these, a group selected from the group consisting of a carboxy group and a hydroxyl group is more preferred, as this contributes to improving the adhesive strength of the resulting adhesive sheet. That is, the (meth)acrylic copolymer preferably has at least one structural unit selected from the group consisting of a structural unit derived from a carboxy group-containing (meth)acrylate and a structural unit derived from a hydroxyl group-containing (meth)acrylate. Examples of the carboxy group-containing monomer include (meth)acrylic acid. Examples of the hydroxy group-containing monomer include 4-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate. These polar functional group-containing monomers may be used alone, or two or more may be used in combination.

[0024] The content of the structural units derived from the carboxy group-containing monomer in the (meth)acrylic copolymer is preferably 0.01% by mass at the lower limit and 7.0% by mass at the upper limit. When the content of the structural units derived from the carboxy group-containing monomer is within this range, the cohesive strength of the bulk of the adhesive layer (Y1) can be appropriately adjusted, and the resulting adhesive sheet has superior adhesive strength. The content of the structural units derived from the carboxy group-containing monomer is more preferably 0.05% by mass at the lower limit, more preferably 5.0% by mass at the upper limit, even more preferably 3.0% by mass at the upper limit, and even more preferably 2.0% by mass at the upper limit.

[0025] The content of the structural units derived from the hydroxyl group-containing monomer in the (meth)acrylic copolymer is preferably 0.01% by mass at the lower limit and 3.0% by mass at the upper limit. When the content of the structural units derived from the hydroxyl group-containing monomer is within this range, the cohesive strength of the bulk of the adhesive layer (Y1) can be appropriately adjusted, and the resulting adhesive sheet has superior adhesive strength. The content of the structural units derived from the hydroxyl group-containing monomer is more preferably 0.05% by mass at the lower limit and 2.0% by mass at the upper limit.

[0026] The total content of the structural units derived from the polar functional group-containing monomer in the (meth)acrylic copolymer preferably has a lower limit of 0.01 mass% and an upper limit of 10.0 mass%. When the total content of the structural units derived from the polar functional group-containing monomer is within this range, the cohesive strength of the bulk of the adhesive layer (Y1) can be appropriately adjusted, and the resulting adhesive sheet has superior adhesive strength. The lower limit of the total content of the structural units derived from the polar functional group-containing monomer is more preferably 0.1 mass%, and the upper limit is more preferably 7.0 mass%, even more preferably 6.0 mass%, and even more preferably 3.0 mass%.

[0027] The (meth)acrylic copolymer may optionally contain structural units derived from other copolymerizable polymerizable monomers other than the structural units derived from the alkyl (meth)acrylates and the structural units derived from the polar functional group-containing monomers described above. Examples of the other polymerizable monomers include benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and polypropylene glycol mono(meth)acrylate. Furthermore, examples of the other polymerizable monomers include various monomers used in general acrylic polymers, such as vinyl carboxylates such as vinyl acetate, and styrene. These other polymerizable monomers may be used alone, or two or more may be used in combination.

[0028] The weight-average molecular weight (Mw) of the (meth)acrylic copolymer preferably has a lower limit of 200,000 and an upper limit of 1,600,000. When the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 200,000 or more, the bulk cohesive strength of the adhesive layer (Y1) is improved, and the adhesive strength of the obtained adhesive sheet is further improved. When the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 1,600,000 or less, the adhesion of the adhesive layer (Y1) to the fluororesin is further improved. The weight-average molecular weight (Mw) of the (meth)acrylic copolymer more preferably has a lower limit of 300,000, a more preferably upper limit of 1,200,000, an even more preferably lower limit of 500,000, and an even more preferably lower limit of 700,000.

[0029] The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the (meth)acrylic copolymer (molecular weight distribution, Mw / Mn) preferably has a lower limit of 1.05 and an upper limit of 10.0. When the (meth)acrylic copolymer has a molecular weight distribution (Mw / Mn) of 1.05 or more, the flexibility of the adhesive layer (Y1) is further improved, and the adhesive strength of the resulting adhesive sheet to fluororesin is further improved. When the (meth)acrylic copolymer has a molecular weight distribution (Mw / Mn) of 10.0 or less, the proportion of low molecular weight components is reduced, the cohesive strength of the bulk of the adhesive layer (Y1) is improved, and the adhesive strength of the resulting adhesive sheet is further improved. The upper limit of the molecular weight distribution (Mw / Mn) of the (meth)acrylic copolymer is more preferably 8.0, even more preferably 6.0, even more preferably 5.0, particularly preferably 4.5, extremely preferably 4.0, and most preferably 3.5.

[0030] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) refer to the weight average molecular weight and number average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC). Specifically, the (meth)acrylic copolymer is diluted 50 times with tetrahydrofuran (THF), and the diluted solution is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate is supplied to a gel permeation chromatograph (Waters, "2690 Separations Module", etc.), and GPC measurement is performed under conditions of a sample flow rate of 1 mL / min and a column temperature of 40 ° C., and the polystyrene-equivalent molecular weight of the (meth)acrylic copolymer is measured to determine the weight average molecular weight (Mw) and number average molecular weight (Mn). As the column, for example, a GPC KF-802.5L (Showa Denko KK) or the like can be used, and as the detector, for example, a differential refractometer or the like can be used. Furthermore, the molecular weight distribution (Mw / Mn) can be derived from the obtained weight average molecular weight (Mw) and number average molecular weight (Mn).

[0031] The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of the (meth)acrylic copolymer can be adjusted to fall within the above ranges by adjusting, for example, the composition, polymerization method, polymerization conditions, etc. of the (meth)acrylic copolymer.

[0032] The glass transition temperature (Tg) of the (meth)acrylic copolymer preferably has a lower limit of −70° C. and an upper limit of −30° C. When the glass transition temperature of the (meth)acrylic copolymer is within the above range, it becomes easier to adjust the shear storage modulus at 25° C. of the adhesive layer (Y1) described below to an appropriate range, and the adhesive sheet obtained has superior adhesive strength to fluororesins. The glass transition temperature (Tg) of the (meth)acrylic copolymer is more preferably −60° C. and more preferably −40° C. The glass transition temperature can be measured using a differential scanning calorimeter (for example, SII Exstar 6000 / DSC 6220 manufactured by Hitachi High-Tech Science Corporation) in a nitrogen atmosphere at a heating rate of 10° C. / min, and the value obtained in the first run can be used.

[0033] As a polymerization method for synthesizing the (meth)acrylic copolymer, a conventionally known method of radically reacting monomers from which the above-mentioned structural units are derived in the presence of a polymerization initiator can be used, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. Among these, solution polymerization is preferred because of its ease of synthesis.

[0034] When solution polymerization is used as the polymerization method, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, diethyl ether, etc. These reaction solvents may be used alone or in combination of two or more.

[0035] Examples of the polymerization initiator include organic peroxides and azo compounds. Examples of the organic peroxides include 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, t-butylperoxypivalate, 2,5-dimethyl-2,5-bis(2-ethylhexanoylperoxy)hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-butylperoxylaurate. Examples of the azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These polymerization initiators may be used alone or in combination of two or more.

[0036] The styrene-based elastomer may be a block copolymer having a block derived from the styrene-based monomer and a block derived from the conjugated diene-based monomer, having rubber elasticity at room temperature, and having a hard segment portion and a soft segment portion, where the block derived from the styrene-based monomer is the hard segment portion and the block derived from the conjugated diene-based monomer is the soft segment portion.

[0037] Examples of the styrene-based monomer include styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, α-methylstyrene, 2,4-dimethylstyrene, 2,4-diisopropylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, vinylethylbenzene, divinylbenzene, trivinylbenzene, divinylnaphthalene, t-butoxystyrene, vinylbenzyldimethylamine, (4-vinylbenzyl)dimethylaminoethyl ether, N,N-dimethylaminoethylstyrene, N,N-dimethylaminomethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2-t-butylstyrene, 3-t-butylstyrene, 4-t-butylstyrene, vinylxylene, vinylnaphthalene, vinylpyridine, diphenylethylene, and tertiary amino group-containing diphenylethylene. Among these, styrene is preferred because of its industrial availability. Examples of the tertiary amino group-containing diphenylethylene include 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene. These styrene-based monomers may be used alone or in combination of two or more.

[0038] Examples of the conjugated diene monomer include isoprene, 1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-heptadiene, 2-phenyl-1,3-butadiene, 3-methyl-1,3-pentadiene, and 2-chloro-1,3-butadiene. Among these, 1,3-butadiene and isoprene are preferred because of their high polymerization reactivity and industrial ease of availability. These conjugated diene monomers may be used alone or in combination of two or more.

[0039] Specific examples of the styrene-based elastomer include styrene-isoprene-styrene (SIS) block copolymers, styrene-butadiene-styrene (SBS) block copolymers, styrene-chloroprene-styrene block copolymers, styrene-ethylene-butylene-styrene copolymers (SEBS), and styrene-ethylene-propylene-styrene copolymers (SEPS). Among these, SIS block copolymers and SBS block copolymers are preferred, with SIS block copolymers being more preferred, because the resulting adhesive sheet is likely to exhibit high adhesive strength and is less likely to peel from the adherend even when immersed in an alkaline chemical solution. These styrene-based elastomers may be used alone, or two or more types may be used in combination.

[0040] The styrene-based elastomer may contain, in addition to a triblock copolymer of a block derived from the styrene-based monomer and a block derived from the conjugated diene-based monomer, a diblock copolymer of a block derived from the styrene-based monomer and a block derived from the conjugated diene-based monomer. The content ratio of the diblock copolymer in the styrene-based elastomer (hereinafter sometimes referred to as the "diblock ratio") is preferably 50% by mass at its lower limit. A diblock ratio of 50% by mass or more improves the adhesion of the adhesive layer (Y1) to an adherend, further improving the adhesive strength of the resulting adhesive sheet. Furthermore, the shear storage modulus at 25°C of the adhesive layer (Y1) described below is appropriately reduced, further improving the flexibility of the adhesive layer (Y1), thereby further improving the adhesive strength of the adhesive layer (Y1) to fluororesins. A more preferred lower limit of the diblock ratio is 70% by mass. From the viewpoint of further improving the cohesive strength of the adhesive layer (Y1), a preferred upper limit of the diblock ratio is 90% by mass. The diblock ratio can be calculated from the peak area ratio of each copolymer measured by gel permeation chromatography (GPC).

[0041] The content of the block derived from the styrene-based monomer in the styrene-based elastomer (hereinafter sometimes referred to as "styrene content") is preferably 20% by mass at its upper limit. When the styrene content is 20% by mass or less, the pressure-sensitive adhesive layer (Y1) does not become too hard, and the adhesion to the adherend is increased, and the pressure-sensitive adhesive strength of the obtained pressure-sensitive adhesive sheet is further improved. A more preferred upper limit of the styrene content is 16% by mass. Furthermore, from the viewpoint of further improving the cohesive strength of the pressure-sensitive adhesive layer (Y1), a preferred lower limit of the styrene content is 8% by mass. The styrene content is １ It can be calculated from the peak area ratio of each block measured by H-NMR.

[0042] The weight-average molecular weight of the styrene-based elastomer preferably has a lower limit of 50,000 and an upper limit of 600,000. When the weight-average molecular weight of the styrene-based elastomer is 50,000 or more, the bulk strength of the adhesive layer (Y1) increases, and the adhesive strength of the resulting adhesive sheet is further improved. When the weight-average molecular weight of the styrene-based elastomer is 600,000 or less, the compatibility of the styrene-based elastomer with other components is further improved. A more preferred lower limit of the weight-average molecular weight of the styrene-based elastomer is 100,000, and a more preferred upper limit is 500,000.

[0043] Examples of the silicone resin include silicone compounds having a polydimethylsiloxane structure, such as KR-3700 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0044] The weight-average molecular weight of the silicone resin preferably has a lower limit of 10,000 and an upper limit of 1,000,000. When the weight-average molecular weight of the silicone resin is 10,000 or more, the bulk strength of the adhesive layer (Y1) increases, and the adhesive force of the resulting adhesive sheet is further improved. When the weight-average molecular weight of the silicone resin is 1,000,000 or less, the compatibility of the silicone resin with other components is further improved. A more preferred lower limit of the weight-average molecular weight of the silicone resin is 50,000, and a more preferred upper limit is 500,000.

[0045] The preferred lower limit of the content of the base polymer (P1) in the adhesive layer (Y1) is 30 mass%, and the preferred upper limit is 99.5 mass%. When the content of the base polymer (P1) is within the above range, the adhesive strength of the adhesive layer (Y1) to fluororesins is further improved. The more preferred lower limit of the content of the base polymer (P1) is 40 mass%, and the more preferred upper limit is 99 mass%, and the even more preferred lower limit is 50 mass%, and the even more preferred upper limit is 95 mass%.

[0046] In the first configuration, the pressure-sensitive adhesive layer (Y1) contains a tackifier resin. Furthermore, in the second configuration, the pressure-sensitive adhesive layer (Y1) preferably contains a tackifier resin. When the pressure-sensitive adhesive layer (Y1) has the first configuration or the second configuration and contains the tackifier resin, the tackifier resin preferably contains a tackifier resin (T1) having at least one structural unit (A) selected from the group consisting of the structural unit (A-1), the structural unit (A-1'), the structural unit (A-2), the structural unit (A-2'), the structural unit (A-3), the structural unit (A-3'), the structural unit (A-4), and the structural unit (A-4') represented by the above formula. By including the tackifier resin (T1) in the pressure-sensitive adhesive layer (Y1), the pressure-sensitive adhesive layer (Y1) can exhibit higher pressure-sensitive adhesive strength, particularly high pressure-sensitive adhesive strength to adherends with low polarity (e.g., fluororesins), and further improve adhesion to the substrate layer described below. In particular, the structural unit (A) is preferably at least one selected from the group consisting of the structural unit (A-1), the structural unit (A-1'), the structural unit (A-2), the structural unit (A-2'), the structural unit (A-3), and the structural unit (A-3'), and more preferably at least one selected from the group consisting of the structural unit (A-1) and the structural unit (A-1'). When the structural unit (A) is at least one selected from the group consisting of the structural unit (A-1) and the structural unit (A-1'), the interaction with the adherend can be further greatly improved, and since the tackifier resin can be made only of biological origin, the burden on the environment can be reduced.

[0047] The tackifier resin (T1) may have the structural unit (A) in a side chain, or in the main chain skeleton or at an end of the main chain skeleton. In particular, the tackifier resin (T1) preferably has the structural unit (A) in the main chain skeleton or at an end of the main chain skeleton, since this allows the tackifier resin to have suitable physical properties required as a tackifier resin.

[0048] In the structural unit (A), R１ ~R ７ respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. Examples of the aliphatic hydrocarbon group include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. Examples of the aromatic hydrocarbon group include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. The polar functional group is not particularly limited, and R １ As the polar functional group other than the hydroxyl group, R ２ is a polar functional group other than a carboxy group, ３ As for OR ４ A polar functional group other than the group represented by R ５ As for NR ６ R ７ Polar functional groups other than those represented by the formula (I) can be used. Specific examples of the polar functional group include an amino group, a carboxy group, a carbonyl group, an alkoxy group, a hydroxyl group, a nitrile group, and a nitro group. Examples of the aliphatic hydrocarbon group having the polar functional group include a group in which one or more hydrogen atoms in the aliphatic hydrocarbon group described above have been substituted with a polar functional group described above. Examples of the aromatic hydrocarbon group having the polar functional group include a group in which one or more hydrogen atoms in the aromatic hydrocarbon group described above have been substituted with a polar functional group described above.

[0049] In the tackifier resin (T1), multiple R １ may be the same or different. １ Similarly, the multiple R １ may be the same or different. １ may be the same or different.

[0050] Similarly, multiple R２ may be the same or different. ２ Similarly, the multiple R ２ may be the same or different. ２ may be the same or different.

[0051] Similarly, multiple R ３ may be the same or different. ３ Similarly, the multiple R ３ may be the same or different. ３ may be the same or different.

[0052] Similarly, multiple R ４ may be the same or different. ４ Similarly, the multiple R ４ may be the same or different. ４ may be the same or different.

[0053] Similarly, multiple R ５ may be the same or different. In addition, multiple R ５ Similarly, the multiple R ５may be the same or different. ５ may be the same or different.

[0054] Similarly, multiple R ６ and R ７ may be the same or different. In addition, multiple R ６ and R ７ Similarly, the multiple R ６ and R ７ may be the same or different. ６ and R ７ may be the same or different.

[0055] In the structural unit (A), n and l are each an integer of 2 or more and 4 or less, and n' and l' are each an integer of 2 or more and 5 or less, and are not particularly limited thereto; however, from the viewpoint of ease of availability of raw materials, n, l, n', and l' are preferably 2 or 3, and n, l, n', and l' are more preferably 3, since this can further increase the adhesive strength of the adhesive layer (Y1).

[0056] In the structural unit (A), m and k are each an integer of 1 or more and 4 or less, and m' and k' are each an integer of 1 or more and 5 or less, and are not particularly limited thereto; however, from the viewpoint of ease of availability of raw materials, m, k, m', and k' are preferably 1, 2, or 3, and more preferably m, k, m', and k' are 1, because this can further increase the adhesive strength of the adhesive layer (Y1).

[0057] Specific examples of the structural unit (A-1) and the structural unit (A-1') include a structural unit derived from dihydroxybenzene or a derivative thereof (when n and n' are 2), and a structural unit derived from trihydroxybenzene or a derivative thereof (when n and n' are 3). These structural units may be used alone, or two or more types may be used in combination. Examples of the dihydroxybenzene or a derivative thereof include resorcinol, pyrocatechol, hydroquinone, dihydroxytoluene, dihydroxyxylene, dihydroxyphenylethylamine hydrochloride, dihydroxybenzoic acid, dihydroxyphenylacetic acid, dihydroxyhydrocinnamic acid, dihydroxyphenylpropionic acid, dihydroxyphenylalanine, dihydroxybenzaldehyde, dihydroxyacetophenone, diacetyldihydroxybenzene, dihydroxyphenyl-2-butanone, dihydroxyphenylmethyl acetate, benzyl dihydroxyphenyl ketone, dihydroxybenzamide, dihydroxymethoxybenzene, dihydroxybenzyl alcohol, dihydroxyphenylethanol, dihydroxyphenyl glycol, dihydroxyphenylacetonitrile, and dihydroxynitrobenzene. Among these, pyrocatechol is preferred because it has little steric hindrance and easily interacts with the adherend. These dihydroxybenzenes or derivatives thereof may be used alone, or two or more may be used in combination. Examples of the trihydroxybenzenes or derivatives thereof include pyrogallol, 1,2,4-trihydroxybenzene, phloroglucinol, trihydroxytoluene, trihydroxydiphenylmethane, 6-hydroxy-L-dopa, gallic acid, methyl gallate, butyl gallate, isobutyl gallate, isoamyl gallate, hexadecyl gallate, stearyl gallate, trihydroxyacetophenone, trihydroxyphenylethanone, trihydroxyphenylbutanone, trihydroxybenzaldehyde, trihydroxybenzamide, and trihydroxynitrobenzene. Among these, pyrogallol is preferred because it has little steric hindrance and easily interacts with the adherend. These trihydroxybenzenes or derivatives thereof may be used alone, or two or more may be used in combination.

[0058] Specific examples of the structural unit (A-2) and the structural unit (A-2') include structural units derived from benzoic acid, salicylic acid, dihydroxybenzoic acid, gallic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, 2-ethylbenzoic acid, 3-ethylbenzoic acid, 4-ethylbenzoic acid, 4-tert-butylbenzoic acid, 2-vinylbenzoic acid, 3-vinylbenzoic acid, 4-vinylbenzoic acid, 4,4'-stilbene dicarboxylic acid, and derivatives thereof. Of these, 4-vinylbenzoic acid is preferred because it has little steric hindrance and easily interacts with the adherend. These structural units may be used alone, or two or more types may be used in combination.

[0059] Specific examples of the structural unit (A-3) and the structural unit (A-3') include a structural unit derived from a dialkoxybenzene or a derivative thereof (when l and l' are 2), and a structural unit derived from a trialkoxybenzene or a derivative thereof (when l and l' are 3). Examples of the dialkoxybenzene or a derivative thereof include 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and 1,4-dimethoxybenzene. Examples of the trialkoxybenzene or a derivative thereof include 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, and 1,3,5-trimethoxybenzene. Of these, 1,2,3-trimethoxybenzene is preferred because it has little steric hindrance and easily interacts with the adherend. These trialkoxybenzenes or derivatives thereof may be used alone, or two or more types may be used in combination.

[0060] Specific examples of the structural unit (A-4) and the structural unit (A-4') include structural units derived from aminobenzene or derivatives thereof (when k and k' are 1). Examples of the aminobenzene or derivatives thereof include aniline, methylaniline, ethylaniline, dimethylaniline, and diethylaniline. These aminobenzenes or derivatives thereof may be used alone, or two or more types may be used in combination.

[0061] The structural unit (A) may consist solely of petroleum-derived materials, but preferably contains a biologically-derived material. The depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products are becoming problems. Therefore, attempts have been made to conserve petroleum resources by using biologically-derived materials instead of petroleum-derived materials. It is preferable for the structural unit (A) to contain a biologically-derived material from the perspective of conserving petroleum resources. Furthermore, if the structural unit (A) contains a biologically-derived material, since biologically-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, it is thought that burning it will not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the perspective of reducing carbon dioxide emissions. Examples of monomers that constitute the structural unit (A) containing a biological material include resorcinol, dihydroxyphenylethylamine hydrochloride, dihydroxyhydrocinnamic acid, dihydroxyphenylalanine, dihydroxybenzaldehyde, dihydroxybenzyl alcohol, pyrogallol, 1,2,4-trihydroxybenzene, phloroglucinol, 6-hydroxy-L-dopa, gallic acid, methyl gallate, butyl gallate, isobutyl gallate, isoamyl gallate, hexadecyl gallate, stearyl gallate, trihydroxyacetophenone, trihydroxybenzaldehyde, trihydroxybenzamide, and trihydroxynitrobenzene.

[0062] The content (by mole) of the structural unit (A) in the tackifier resin (T1) is not particularly limited, but a preferred lower limit is 1 mol% and a preferred upper limit is 60 mol%. When the content of the structural unit (A) is 1 mol% or more, by incorporating the tackifier resin (T1) in the adhesive layer (Y1), the adhesive strength of the adhesive layer (Y1) can be further increased. When the content of the structural unit (A) is 60 mol% or less, the tackifier resin (T1) can have suitable physical properties required as a tackifier resin. A more preferred lower limit of the content of the structural unit (A) is 5 mol%, a more preferred upper limit is 50 mol%, an even more preferred lower limit is 10 mol%, and an even more preferred upper limit is 30 mol%. Furthermore, the content (by mass) of the structural unit (A) in the tackifier resin (T1) is not particularly limited, but a preferred lower limit is 0.9 mass% and a preferred upper limit is 60 mass%. When the content of the structural unit (A) is 0.9% by mass or more, by blending the tackifier resin (T1) in the adhesive layer (Y1), the adhesive strength of the adhesive layer (Y1) can be further increased. When the content of the structural unit (A) is 60% by mass or less, the tackifier resin (T1) can have suitable physical properties required as a tackifier resin. The lower limit of the content of the structural unit (A) is more preferably 5% by mass, the upper limit is more preferably 50% by mass, the even more preferably 10% by mass, and the even more preferably 30% by mass.

[0063] The tackifier resin (T1) preferably further contains a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers. When the tackifier resin (T1) contains the structural unit (B), the adhesive strength of the pressure-sensitive adhesive layer (Y1) can be further increased. Furthermore, from the viewpoint of improving the compatibility between the tackifier resin (T1) and the base polymer (P1), a structural unit derived from a terpene monomer is preferred. Since the structural unit derived from the terpene monomer contains an aliphatic hydrocarbon group having an unsaturated double bond, when the tackifier resin (T1) contains a structural unit derived from a terpene monomer, the compatibility between the tackifier resin (T1) and the base polymer (P1) is improved, and a decrease in the adhesive strength of the pressure-sensitive adhesive layer (Y1) due to poor compatibility can be suppressed.

[0064] Examples of the terpene monomer include α-pinene, β-pinene, limonene, dipentene, δ-3-carene, dimethyloctatriene, alloocimene, myrcene, ocimene, linalool, and cosmene. Among these, α-pinene, β-pinene, or limonene is preferred because it can further increase the adhesive strength of the adhesive layer (Y1). The vinyl monomer is not particularly limited, but from the viewpoint of improving the compatibility between the tackifier resin (T1) and the base polymer, a vinyl monomer that does not have a structure containing two or more aromatic rings in one molecule (for example, a naphthalene structure, an anthracene structure, a biphenyl structure, an anthraquinone structure, a benzophenone structure, etc.) is preferred. Examples of the vinyl monomer not having a structure containing two or more aromatic rings per molecule include ethylene, propylene, butylene, hexene, vinyl acetate, vinyl chloride, styrene, α-methylstyrene, coumarone, indene, vinyltoluene, divinylbenzene, divinyltoluene, and 2-phenyl-2-butene. Among these, styrene is preferred because it can further enhance the adhesive strength of the adhesive layer (Y1). These monomers (b) may be used alone or in combination of two or more.

[0065] The structural unit (B) may consist solely of petroleum-derived materials, but preferably contains a biologically-derived material. The depletion of petroleum resources and carbon dioxide emissions from the combustion of petroleum-derived products are becoming increasingly problematic. Therefore, attempts have been made to conserve petroleum resources by using biologically-derived materials instead of petroleum-derived materials. It is preferable for the structural unit (B) to contain a biologically-derived material from the perspective of conserving petroleum resources. Furthermore, since the biologically-derived material is originally produced by absorbing carbon dioxide from the atmosphere, its combustion is thought to not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the perspective of reducing carbon dioxide emissions. Examples of the monomer (b) constituting the structural unit (B) containing a biologically-derived material include terpene monomers, ethylene, propylene, and hexene.

[0066] The content of the structural unit (B) in the tackifier resin (T1) is preferably 40 mol% at the lower limit and 99 mol% at the upper limit. When the content of the structural unit (B) is 40 mol% or more, the tackifier resin (T1) can have suitable physical properties required as a tackifier resin. When the content of the structural unit (B) is 99 mol% or less, the content of the structural unit (A) can be sufficiently ensured, thereby further increasing the adhesive strength of the adhesive layer (Y1), and in particular, further increasing the adhesive strength even to adherends with low polarity. The lower limit of the content of the structural unit (B) is more preferably 50 mol%, and the upper limit is more preferably 90 mol%.

[0067] The tackifier resin (T1) is not particularly limited as long as it is a compound having the structural unit (A), but is preferably a copolymer having a structure represented by the following formula: In particular, when the structural unit (A) is contained in the main chain skeleton or at the end of the main chain skeleton, it is preferably a copolymer having a structure represented by the following formula: A copolymer having such a structure is a copolymer obtained by a method using cationic polymerization as described below, and can further increase the tackifying and adhesive strength of the pressure-sensitive adhesive layer (Y1), and in particular can further increase the tackifying and adhesive strength even to adherends with low polarity.

[0068]

[0069] In the formula, A represents the structural unit (A), B represents the structural unit (B), and s and t each represent an integer of 1 or greater. * represents a linking moiety.

[0070] The tackifier resin (T1) is not particularly limited as long as it is a compound having the structural unit (A), but is preferably a copolymer having the structural unit (A) and the structural unit (B), and may further contain other structural units. When the tackifier resin (T1) is a copolymer having the structural unit (A) and the structural unit (B), the structural units (A) and (B) may be copolymerized randomly, or may be copolymerized with regularity or periodicity, for example, by forming block segments and then bonding to each other.

[0071] The tackifier resin (T1) preferably has an aliphatic hydrocarbon group having an unsaturated double bond. The tackifier resin (T1) may have the aliphatic hydrocarbon group having an unsaturated double bond in the structural unit (A) or the structural unit (B), or in another structural unit. From the viewpoint of ease of synthesis and improving the compatibility between the tackifier resin (T1) and the base polymer (P1), particularly the compatibility between the tackifier resin (T1) and a styrene-based elastomer, it is preferable for the aliphatic hydrocarbon group having an unsaturated double bond to be contained in the structural unit (B) or another structural unit. The structural unit (B) or other structural unit having the aliphatic hydrocarbon group having an unsaturated double bond is not particularly limited, but a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers is preferred. That is, the tackifier resin (T1) preferably has the aliphatic hydrocarbon group having an unsaturated double bond in a structural unit (B) derived from at least one monomer (b) selected from the group consisting of a terpene monomer and a vinyl monomer, and particularly preferably in a structural unit derived from a terpene monomer, since this can further increase the tackifying and adhesive strength of the pressure-sensitive adhesive layer (Y1).

[0072] Furthermore, examples of the other structural units include structural units derived from other phenolic monomers not included in the structural unit (A), structural units derived from maleic anhydride, etc. Examples of the other phenolic monomers include phenol, cresol, xylenol, propylphenol, norylphenol, methoxyphenol, bromophenol, bisphenol A, bisphenol F, bisphenol S, dihydroxynaphthalene, etc. These other phenolic monomers may be used alone or in combination of two or more.

[0073] The molecular weight of the tackifier resin (T1) is not particularly limited, but the preferred lower limit of the weight average molecular weight (Mw) is 400, and the preferred upper limit is 10,000. If the weight average molecular weight (Mw) of the tackifier resin (T1) is within the above range, the tackifier resin (T1) can have suitable physical properties required as a tackifier resin. The more preferred lower limit of the weight average molecular weight (Mw) of the tackifier resin (T1) is 500, the more preferred upper limit is 5,000, the even more preferred lower limit is 550, and the even more preferred upper limit is 3,000. The weight average molecular weight (Mw) can be adjusted to fall within the above range by, for example, adjusting the composition, polymerization method, polymerization conditions, etc. of the tackifier resin (T1).

[0074] The Young's modulus of the tackifier resin (T1) at 25°C is preferably 10 MPa at its lower limit. When the Young's modulus of the tackifier resin (T1) at 25°C is 10 MPa or more, the tackifier resin (T1) has appropriate hardness and can have suitable physical properties required as a tackifier resin. The lower limit of the Young's modulus of the tackifier resin (T1) at 25°C is more preferably 50 MPa, and even more preferably 70 MPa. Furthermore, from the viewpoint of preventing the adhesive layer (Y1) from becoming too hard and reducing the adhesive strength, the upper limit of the Young's modulus of the tackifier resin (T1) at 25°C is preferably 10,000 MPa, and more preferably 5,000 MPa. The Young's modulus of the tackifier resin (T1) at 25°C can be measured by performing a tensile test using a tensile tester (e.g., "Tensilon" manufactured by ORIENTEC Co., Ltd.) under conditions of a pulling speed of 200 mm / min, a gripper distance of 15 mm, and 25°C. The measurement sample in this case can be prepared, for example, by filling a mold having a size of 10 × 50 mm with the tackifier resin (T1) and melting it at a temperature 100°C higher than the glass transition temperature to prepare a test piece having a thickness of 1 mm.

[0075] The Young's modulus at 25°C of the tackifier resin (T1) can be adjusted to fall within the above range by, for example, adjusting the molecular weight or weight average molecular weight of the tackifier resin (T1), or the composition and content of the structural unit (A) and the structural unit (B) in the tackifier resin (T1).

[0076] The glass transition temperature of the tackifier resin (T1) preferably has a lower limit of 0°C and an upper limit of 200°C. If the glass transition temperature of the tackifier resin (T1) is within the above range, the Young's modulus at 25°C of the tackifier resin (T1) can be easily adjusted to be within the above range, and the tackifier resin (T1) can have suitable physical properties required as a tackifier resin. The lower limit of the glass transition temperature of the tackifier resin (T1) is more preferably 10°C and the upper limit is more preferably 150°C.

[0077] The iodine value of the tackifier resin (T1) is preferably 2 g / 100 g at its lower limit and 180 g / 100 g at its upper limit. When the iodine value of the tackifier resin (T1) is 2 g / 100 g or more, it is possible to prevent a decrease in the adhesive strength of the adhesive layer (Y1) due to a deterioration in the compatibility between the tackifier resin (T1) and the base polymer (P1). When the iodine value of the tackifier resin (T1) is 180 g / 100 g or less, it is possible to further increase the adhesive strength of the adhesive layer (Y1), and in particular, to further increase the adhesive strength even to adherends with low polarity. The iodine value of the tackifier resin (T1) is more preferably 70 g / 100 g at its lower limit and 170 g / 100 g at its upper limit. The iodine value is an index showing the amount of unsaturated double bonds (amount of C═C bonds) and is measured in accordance with the method described in "JIS K 0070:1992."

[0078] The preferred lower limit of the content of biologically-derived carbon (carbon atoms) in the total carbon (carbon atoms) in the tackifier resin (T1) is 10%. A biologically-derived carbon content of 10% or more is an indicator of a "bio-based product." A biologically-derived carbon content of 10% or more in the tackifier resin (T1) is preferred from the perspective of saving petroleum resources and reducing carbon dioxide emissions. A more preferred lower limit of the biologically-derived carbon content in the tackifier resin (T1) is 30%, an even more preferred lower limit is 60%, an even more preferred lower limit is 70%, and an especially preferred lower limit is 90%. The upper limit of the biologically-derived carbon content in the tackifier resin (T1) is not particularly limited and may be 100%. Note that biologically-derived carbon contains a certain percentage of the radioactive isotope (C-14), whereas petroleum-derived carbon contains almost no C-14. Therefore, the biologically-derived carbon content in the tackifier resin (T1) can be calculated by measuring the concentration of C-14 contained in the compound. Specifically, it can be measured in accordance with ASTM D6866-22, a standard used in many bioplastic industries.

[0079] The tackifier resin (T1) also includes hydrogenated products of the above-mentioned compounds. The hydrogenated products are compounds in which the carbon-carbon double bonds present in the above-mentioned tackifier resin (T1) are at least partially saturated by hydrogenation. That is, the pressure-sensitive adhesive layer (Y1) may contain a hydrogenated product in which some of the carbon-carbon double bonds in the tackifier resin (T1) are hydrogenated, or a hydrogenated product in which all of the carbon-carbon double bonds in the tackifier resin (T1) are hydrogenated. Even such hydrogenated products are suitably used as the tackifier resin to be blended in the pressure-sensitive adhesive layer (Y1), and can increase the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer (Y1), and can particularly increase the pressure-sensitive adhesive strength even to adherends with low polarity.

[0080] Although there are no particular limitations on the method for producing the tackifier resin (T1), when the structural unit (A) is contained in the main chain skeleton or at the end of the main chain skeleton, the following method is preferred, for example: That is, a method of copolymerizing a monomer (a) constituting the structural unit (A) with at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers constituting the structural unit (B) (hereinafter, also referred to as production method [I]).

[0081] The monomer (a) is preferably at least one selected from the group consisting of monomer (a-1), monomer (a-2), monomer (a-3), and monomer (a-4) represented by the following formulas:

[0082]

[0083]

[0084]

[0085]

[0086] In formulas (a-1) to (a-4), R １ ~R ７respectively represent a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. n'' represents an integer of 2 or more and 5 or less, preferably 2 or 3, and more preferably 3. m'' represents an integer of 1 or more and 5 or less. l'' represents an integer of 2 or more and 5 or less. k'' represents an integer of 1 or more and 5 or less.

[0087] In the method [I] for producing the tackifier resin (T1), it is preferable to copolymerize the monomer (a) and the monomer (b) by cationic polymerization. By using cationic polymerization, the monomer (a) and the monomer (b) can be copolymerized without first protecting the functional groups of the monomer (a), such as the phenolic hydroxyl group, carboxy group, alkoxy group, and amino group, by chemical modification, and subsequent deprotection is also unnecessary. Therefore, the monomer (a) and the monomer (b) can be copolymerized by a simpler one-step reaction process, which also leads to a reduction in impurities and an improvement in yield.

[0088] As a method for copolymerizing the monomer (a) and the monomer (b) by cationic polymerization, a method in which the monomer (a) and the monomer (b) are reacted in the presence of a Lewis acid is preferred. According to such a method, it is believed that a cation of the monomer (b) is generated, and the cationic polymerization of the monomers (b) proceeds, while the Friedel-Crafts alkylation reaction between the monomers (a) and (b) proceeds. By repeating such a reaction, a copolymer having a structural unit (A) derived from the monomer (a) and a structural unit (B) derived from the monomer (b) can be obtained. The Lewis acid is not particularly limited, and a conventionally known Lewis acid can be used, for example, aluminum chloride (AlCl ３ ), diethylaluminum chloride (Et ２ AlCl ２ ), tin(IV) chloride (SnCl ４ ), titanium(IV) chloride (TiCl ４ ), boron trichloride (BCl ３ ), boron trifluoride ether complex (BF３ Among them, aluminum chloride (AlCl ) is preferred because it can produce a copolymer in a higher yield. ３ ) is preferred.

[0089] More specifically, for example, pyrogallol is used as the monomer (a) and α-pinene is used as the monomer (b), and these are reacted with aluminum chloride (AlCl), which is a Lewis acid, to form a copolymer. ３ When the reaction is carried out in the presence of a monomer (b), the reaction shown in the following scheme is believed to proceed. That is, a cation of α-pinene, the monomer (b), is generated, and cationic polymerization of α-pinenes proceeds (upper part of the scheme below), while a Friedel-Crafts alkylation reaction between pyrogallol, the monomer (a), and α-pinene, the monomer (b), proceeds (middle part of the scheme below). By repeating this reaction, a copolymer having structural units derived from pyrogallol and structural units derived from α-pinene can be obtained (lower part of the scheme below). Note that such a copolymer has structural units derived from pyrogallol in the main chain skeleton or at the terminal of the main chain skeleton.

[0090]

[0091] In the formula, s and t each represent an integer of 1 or more, and * represents a linking moiety.

[0092] When the structural unit (A) is contained in a side chain, the following method is preferred as a method for producing the tackifier resin (T1): That is, a method of copolymerizing a monomer (a') obtained by further introducing an unsaturated double bond into the monomer (a) constituting the structural unit (A) with at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers constituting the structural unit (B) (hereinafter, also referred to as production method [II]).

[0093] Examples of the monomer (a') include 2-vinylbenzoic acid, 3-vinylbenzoic acid, 4-vinylbenzoic acid, and 4,4'-stilbene dicarboxylic acid. Among these, 4-vinylbenzoic acid is preferred because it has little steric hindrance and easily interacts with the adherend. These monomers (a') may be used alone or in combination of two or more.

[0094] In the method [II] for producing the tackifier resin (T1), it is preferable to copolymerize the monomer (a') and the monomer (b) by cationic polymerization, as in the method [I] for producing the tackifier resin (T1). A preferred method for copolymerizing the monomer (a') and the monomer (b) by cationic polymerization is to react the monomer (a') and the monomer (b) in the presence of a Lewis acid as described above. According to this method, cationic polymerization of the unsaturated double bond in the monomer (a') and the unsaturated double bond in the monomer (b) proceeds, thereby producing a copolymer having the structural unit (A) derived from the monomer (a') and the structural unit (B) derived from the monomer (b).

[0095] The tackifier resin (T1) can enhance the adhesive strength of the adhesive layer (Y1) even in a smaller amount than conventional tackifier resins. The content of the tackifier resin (T1) relative to 100 parts by mass of the base polymer (P1) preferably has a lower limit of 5 parts by mass and an upper limit of 50 parts by mass. When the content of the tackifier resin (T1) is 5 parts by mass or more, the adhesive strength of the adhesive layer (Y1) can be further enhanced, and in particular, the adhesive strength can be further enhanced even for adherends with low polarity (e.g., fluororesins). When the content of the tackifier resin (T1) is 50 parts by mass or less, a decrease in the adhesive strength due to excessive hardness of the adhesive layer (Y1) can be suppressed. The lower limit of the content of the tackifier resin (T1) is more preferably 10 parts by mass, and the upper limit is more preferably 35 parts by mass, even more preferably 30 parts by mass, and even more preferably 20 parts by mass.

[0096] When the composition has the first or second structure and contains the tackifier resin, the tackifier resin preferably contains at least one tackifier resin (T2) selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum-based resins. When the tackifier resin contains the tackifier resin (T2), the adhesive strength of the pressure-sensitive adhesive layer (Y1) can be further enhanced. In this specification, the term "terpene resin" refers to a resin that has structural units derived from monoterpenes and does not have structural units containing aromatic compounds, and the term "terpene phenol resin" refers to a resin that has structural units derived from monoterpenes and structural units derived from phenol. Furthermore, the structural units (A-1) and (A-1') are not considered to be structural units derived from phenol.

[0097] The softening temperature of the tackifier resin (T2) preferably has a lower limit of 50°C and an upper limit of 200°C. When the softening temperature of the tackifier resin (T2) is 50°C or higher, it is possible to prevent the pressure-sensitive adhesive layer (Y1) from becoming too soft and thereby reducing its adhesive strength. When the softening temperature of the tackifier resin (T2) is 200°C or lower, it is possible to improve the wettability of the interface of the pressure-sensitive adhesive layer (Y1), thereby preventing interfacial peeling. In addition, the glass transition temperature (Tg) of the (meth)acrylic copolymer is further reduced. As a result, the shear storage modulus at 25°C of the pressure-sensitive adhesive layer (Y1) described below is appropriately reduced, and the flexibility of the pressure-sensitive adhesive layer (Y1) is further improved, thereby further improving the adhesive strength of the pressure-sensitive adhesive layer (Y1) to the fluororesin. The softening temperature of the tackifier resin (T2) more preferably has a lower limit of 70°C and an upper limit of 150°C. The softening temperature of the tackifier resin (T2) is the softening temperature measured in accordance with JIS K 2207 (ring and ball method).

[0098] The tackifier resin (T2) preferably has a lower limit of 0 mgKOH / g and an upper limit of 200 mgKOH / g for the hydroxyl value. When the tackifier resin (T2) has a hydroxyl value within the above range, the wettability of the interface of the pressure-sensitive adhesive layer (Y1) is improved, and interfacial peeling can be suppressed. The hydroxyl value of the tackifier resin (T2) is more preferably 30 mgKOH / g for the lower limit and 130 mgKOH / g for the upper limit. The hydroxyl value can be measured according to JIS K 1557 (phthalic anhydride method).

[0099] Examples of the rosin ester resins include Pine Crystal KE-359 (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value: 40 mg KOH / g, softening temperature: 100°C). Examples of the terpene resins include YS Resin PX1250 (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value: 0 mg KOH / g, softening temperature: 125°C). Examples of the terpene phenol resins include YS Polystar G150 (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value: 120 mg KOH / g, softening temperature: 150°C). Examples of the petroleum resins include Alcon P-140 (manufactured by Arakawa Chemical Co., Ltd., hydroxyl value: 0 mg KOH / g, softening temperature: 140°C).

[0100] The content of the tackifier resin (T2) relative to 100 parts by mass of the base polymer (P1) is preferably 10 parts by mass at least and 200 parts by mass at most. When the content of the tackifier resin (T2) is 10 parts by mass or more, the adhesive strength of the adhesive layer (Y1) can be further increased. When the content of the tackifier resin (T2) is 200 parts by mass or less, the adhesive strength of the adhesive layer (Y1) can be prevented from decreasing due to excessive hardness. The lower limit of the content of the tackifier resin (T2) is more preferably 15 parts by mass, and the upper limit is more preferably 160 parts by mass, even more preferably 140 parts by mass, still more preferably 100 parts by mass, particularly preferably 60 parts by mass, extremely preferably 50 parts by mass, and most preferably 40 parts by mass.

[0101]

[0042] When the base polymer (P1) comprises a (meth)acrylic copolymer, the adhesive layer (Y1) preferably further comprises a curing agent. By including a curing agent in the adhesive layer (Y1), the (meth)acrylic copolymer can form a structure in which it is crosslinked by chemical crosslinking, thereby further improving the cohesive strength of the bulk of the adhesive layer (Y1) and further increasing the gel fraction of the adhesive layer (Y1), which will be described later, thereby further improving the adhesive strength of the adhesive sheet obtained.

[0102] Examples of the curing agent include an isocyanate-based curing agent, an aziridine-based curing agent, an epoxy-based curing agent, a metal chelate-type curing agent, etc. Among these, the curing agent preferably contains an isocyanate-based curing agent, from the viewpoint of enabling appropriate chemical crosslinking of the (meth)acrylic copolymer and further improving the adhesive strength of the adhesive layer (Y1).

[0103] Examples of the isocyanate curing agent include Takenate 500 (manufactured by Mitsui Chemicals, Inc.) and Desmodur L-75 (manufactured by Covestro).

[0104] The content of the curing agent relative to 100 parts by mass of the (meth)acrylic copolymer is preferably 0.01 parts by mass at the lower limit and 10 parts by mass at the upper limit. By having the content of the curing agent within the above range, appropriate chemical crosslinking of the (meth)acrylic copolymer is possible, and the adhesive strength of the resulting adhesive sheet is further improved. The lower limit of the content of the curing agent is more preferably 0.1 parts by mass, and the upper limit is more preferably 5.0 parts by mass, and the even more preferably 0.5 parts by mass, and the even more preferably 2.0 parts by mass at the upper limit.

[0105]

[0033] When the base polymer (P1) contains the silicone resin, the adhesive layer (Y1) preferably further contains a catalyst. When the adhesive layer (Y1) contains the catalyst, the silicone resin can form a structure in which it is appropriately crosslinked, thereby further improving the bulk cohesive strength of the adhesive layer (Y1) and further increasing the gel fraction of the adhesive layer (Y1), which will be described later, thereby further improving the adhesive strength of the adhesive layer (Y1).

[0106] The catalyst may be, for example, a platinum catalyst, such as CAT-PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0107] The content of the catalyst relative to 100 parts by mass of the silicone resin is preferably 0.1 parts by mass at the lower limit and 10 parts by mass at the upper limit. By having the content of the catalyst within the above range, the silicone resin can be crosslinked appropriately, and the adhesive strength of the obtained adhesive sheet can be further improved. The lower limit of the content of the catalyst is more preferably 0.2 parts by mass, and the upper limit is more preferably 8 parts by mass, and the even more preferably 0.3 parts by mass, and the even more preferably 6 parts by mass at the upper limit.

[0108] The pressure-sensitive adhesive layer (Y1) may further contain a colorant for the purpose of imparting light-blocking properties. Examples of the colorant include carbon black, aniline black, titanium oxide, etc. Among these, carbon black is preferred because it is relatively inexpensive and chemically stable.

[0109] The pressure-sensitive adhesive layer (Y1) may contain, as necessary, conventionally known fine particles and additives such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers.

[0110] The adhesive layer (Y1) is required to exhibit sufficient adhesive strength immediately after being attached to an adherend at room temperature, and therefore is preferably not a hot-melt adhesive layer. In this specification, the term "hot-melt adhesive layer" means an adhesive layer that is melted by heating and adhered to an adherend.

[0111] In the second configuration, the pressure-sensitive adhesive layer (Y1) has a lower limit of 180° peel strength from polytetrafluoroethylene at 23°C of 5.0 N / 25 mm. When the pressure-sensitive adhesive layer (Y1) has a 180° peel strength from polytetrafluoroethylene at 23°C of 5.0 N / 25 mm or more, the pressure-sensitive adhesive sheet of the present invention has excellent pressure-sensitive adhesive strength to fluororesins. In the second configuration, the pressure-sensitive adhesive layer (Y1) has a preferred lower limit of 180° peel strength from polytetrafluoroethylene at 23°C of 7.0 N / 25 mm, and a more preferred lower limit of 10.0 N / 25 mm. Furthermore, in the first configuration, the pressure-sensitive adhesive layer (Y1) has a preferred lower limit of 180° peel strength from polytetrafluoroethylene at 23°C of 2.5 N / 25 mm. When the 180° peel strength of the adhesive layer (Y1) from polytetrafluoroethylene at 23°C is 2.5 N / 25 mm or more, the adhesive sheet of the present invention has superior adhesive strength to fluororesins. In the second configuration, the lower limit of the 180° peel strength of the adhesive layer (Y1) from polytetrafluoroethylene at 23°C is more preferably 3.0 N / 25 mm, and even more preferably 3.5 N / 25 mm. There is no particular upper limit to the 180° peel strength of the adhesive layer (Y1) from polytetrafluoroethylene at 23°C, but about 100 N / 25 mm is a practical upper limit. The 180° peel strength of the adhesive layer (Y1) from polytetrafluoroethylene at 23°C can be measured by the following method. That is, the adhesive sheet is cut into a size of 25 mm wide x 100 mm long, and then a 2 kg rubber roller is used to make one reciprocating motion at a speed of 300 mm / min, thereby pressing the sheet onto a 2 μm thick polytetrafluoroethylene plate (Yodoflon, manufactured by Yodogawa Hutech Co., Ltd., etc.). The sheet is then left to stand for 20 minutes in an environment of 23°C and 50% RH to cure, thereby preparing a test sample.

[0123] The obtained test sample is subjected to a 180° peel test in accordance with JIS Z 0237 using a tensile tester (such as "Tensilon" manufactured by ORIENTEC Co., Ltd.) under conditions of 23°C, 50% RH and a peel rate of 300 mm / min, and the adhesive sheet is peeled from the polytetrafluoroethylene plate, whereby the 180° peel strength of the adhesive layer (Y1) at 23°C from polytetrafluoroethylene can be measured.

[0112]

[0063] Examples of a method for adjusting the 180° peel strength of the pressure-sensitive adhesive layer (Y1) against polytetrafluoroethylene at 23°C within the above-mentioned range include a method for changing the type or structural unit of the base polymer (P1) contained in the pressure-sensitive adhesive layer (Y1) (for example, the copolymerization ratio or composition of P1), a method for adjusting the type or content of a tackifier resin contained in the pressure-sensitive adhesive layer (Y1), a method for changing the thickness of the pressure-sensitive adhesive layer (Y1), a method for changing the base material, and the like.

[0113] The pressure-sensitive adhesive layer (Y1) preferably has a loss tangent (tan δ) measured at a frequency of 10 Hz in a dynamic viscoelastic measurement (hereinafter sometimes referred to as "the loss tangent of the pressure-sensitive adhesive layer (Y1) measured at a frequency of 10 Hz") that has a peak in a temperature range of -30°C or more and 15°C or less. When the loss tangent (tan δ) of the pressure-sensitive adhesive layer (Y1) measured at a frequency of 10 Hz has a peak in a temperature range of -30°C or more, the pressure-sensitive adhesive strength of the pressure-sensitive adhesive layer (Y1) to fluororesin is further improved. Furthermore, when the loss tangent (tan δ) of the pressure-sensitive adhesive layer (Y1) measured at a frequency of 10 Hz has a peak in a temperature range of 15°C or less, the zipping phenomenon that occurs when peeling off a film that protects the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet can be suppressed, and the resulting pressure-sensitive adhesive sheet can be used without losing its pressure-sensitive adhesive strength. The peak temperature at which the loss tangent of the pressure-sensitive adhesive layer (Y1) measured at a frequency of 10 Hz reaches a peak (hereinafter, may be simply referred to as "peak temperature of loss tangent") is more preferably −25°C, more preferably 13°C, still more preferably −20°C, and still more preferably 11°C.

[0114] The adhesive layer (Y1) has a shear storage modulus at 25°C measured at a frequency of 10 Hz in dynamic viscoelasticity measurement of 1.0 × 10 ４ Pa, the preferred upper limit is 5.0 × 10 ５ Pa. When the shear storage modulus at 25°C of the adhesive layer (Y1) is within the above range, the adhesive sheet to be obtained has superior adhesive strength. In addition, the flexibility of the adhesive layer (Y1) is excellent, and the adhesive strength of the adhesive layer (Y1) to fluororesins is further improved. A more preferable lower limit of the shear storage modulus at 25°C of the adhesive layer (Y1) is 3.0 x 10 ４ Pa, and a more preferable upper limit is 4.0 × 10 ５ Pa, and a more preferable lower limit is 5.0 × 10 ４ Pa, and a more preferable upper limit is 3.5×10 ５ It is Pa.

[0115] The peak temperature of the loss tangent of the pressure-sensitive adhesive layer (Y1) measured at a frequency of 10 Hz and the shear storage modulus of the pressure-sensitive adhesive layer (Y1) at 25°C can be measured by dynamic viscoelasticity measurement. Specifically, a measurement sample consisting of only the pressure-sensitive adhesive layer is prepared by laminating pressure-sensitive adhesive layers to a thickness of 1 mm, and the shear storage modulus of the pressure-sensitive adhesive layer (Y1) can be measured by measuring the dynamic viscoelasticity spectrum of the obtained measurement sample from -50°C to 200°C using a dynamic viscoelasticity measuring device such as a viscoelasticity spectrometer (e.g., "DVA-200" manufactured by IT Measurement Control Co., Ltd.) under conditions of shear mode, a heating rate of 5°C / min, and a measurement frequency of 10 Hz. In addition, the peak temperature of the loss tangent of the pressure-sensitive adhesive layer (Y1) can be obtained from the dynamic viscoelasticity spectrum obtained at this time.

[0116] The peak temperature of the loss tangent (tan δ) of the pressure-sensitive adhesive layer (Y1) measured at a frequency of 10 Hz and the shear storage modulus at 25°C of the pressure-sensitive adhesive layer (Y1) can be adjusted by the types and content ratios of monomers constituting the (meth)acrylic copolymer, the weight average molecular weight of the (meth)acrylic copolymer, the presence or absence of the tackifier resin (T2), the types and contents of the tackifier resin (T1) and the tackifier resin (T2), the gel fraction of the pressure-sensitive adhesive layer (Y1) described later, and the like.

[0117] The gel fraction of the adhesive layer (Y1) preferably has a lower limit of 0 mass% and an upper limit of 99 mass%. When the gel fraction of the adhesive layer (Y1) is 0 mass% or more, the bulk strength of the adhesive layer (Y1) increases, and the adhesive sheet obtained has superior adhesive strength. When the gel fraction of the adhesive layer (Y1) is 99 mass% or less, the shear storage modulus at 25°C of the adhesive layer (Y1) described above decreases appropriately, the flexibility of the adhesive layer (Y1) is further improved, and the adhesive strength of the adhesive layer (Y1) to fluororesin is further improved. The gel fraction of the adhesive layer (Y1) is more preferably 10 mass% or less, and more preferably 70 mass% or less, and even more preferably 20 mass% or less, and even more preferably 65 mass% or less, and even more preferably 25 mass% or less, and even more preferably 60 mass% or less, and particularly preferably 50 mass% or less. The gel fraction of the pressure-sensitive adhesive layer (Y1) can be measured by the following method, etc. A test piece is prepared by cutting the pressure-sensitive adhesive sheet into a flat rectangular shape of 50 mm width x 100 mm length. The test piece is immersed in an organic solvent at 23°C for 24 hours, then removed from the organic solvent and dried at 110°C for 1 hour. The organic solvent can be ethyl acetate when the base polymer (P1) is a (meth)acrylic copolymer, or toluene when the base polymer (P1) is a styrene-based elastomer or silicone resin. The mass of the test piece after drying is measured, and the gel fraction is calculated using the following formula (1). It is assumed that no release film for protecting the pressure-sensitive adhesive layer (Y1) is laminated on the test piece. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １-W ０ ) (1) (W ０ : Mass of the substrate, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0118]

[0123] The gel fraction of the pressure-sensitive adhesive layer (Y1) can be adjusted to within the above range, for example, by adjusting the type and content ratio of the monomers constituting the (meth)acrylic copolymer, the weight average molecular weight of the (meth)acrylic copolymer, the type and content of the curing agent, etc.

[0119] The thickness of the adhesive layer (Y1) is preferably 25 μm at its lower limit and 1000 μm at its upper limit. When the thickness of the adhesive layer (Y1) is within this range, the adhesive layer (Y1) can have sufficient adhesive strength. The thickness of the adhesive layer (Y1) is more preferably 40 μm at its lower limit, more preferably 500 μm at its upper limit, even more preferably 50 μm at its lower limit, even more preferably 300 μm at its upper limit, still more preferably 80 μm at its lower limit, and particularly preferably 100 μm at its lower limit.

[0120] In the first configuration, the adhesive layer (Y2) is a hot-melt adhesive layer. In the second configuration, the adhesive layer (Y2) is preferably a hot-melt adhesive layer.

[0121] The preferred lower limit of the softening point of the adhesive layer (Y2) is 40°C. When the softening point of the adhesive layer (Y2) is 40°C or higher, the adhesive sheet of the present invention has excellent lamination workability. The more preferred lower limit of the softening point of the adhesive layer (Y2) is 50°C, and even more preferred lower limit is 60°C. The preferred upper limit of the softening point of the adhesive layer (Y2) is 250°C. When the softening point of the adhesive layer (Y2) is 250°C or lower, material deterioration during heating can be suppressed. The more preferred upper limit of the softening point of the adhesive layer (Y2) is 230°C, and even more preferred upper limit is 200°C. The softening point of the adhesive layer (Y2) can be measured in accordance with JIS K 6863.

[0122] When the adhesive sheet is pressure-bonded on the adhesive layer (Y2) side at 150°C under pressure of 0.1 MPa for 10 minutes, the preferred lower limit of the 180° peel strength from SUS at 23°C (hereinafter sometimes simply referred to as "the 180° peel strength from SUS at 23°C of the adhesive layer (Y2) after heating") is 10 N / 25 mm. When the adhesive layer (Y2) has a 180° peel strength from SUS at 23°C after heating of 10 N / 25 mm or more, the adhesive layer (Y2) can exhibit excellent adhesive strength upon heating, and therefore the adhesive sheet of the present invention can achieve both excellent lamination workability and excellent adhesive strength. The preferred lower limit of the 180° peel strength from SUS at 23°C of the adhesive layer (Y2) after heating is 15 N / 25 mm, and the more preferred upper limit is 20 N / 25 mm.

[0033] Furthermore, there is no particularly preferred upper limit to the 180° peel strength of the pressure-sensitive adhesive layer (Y2) from SUS at 23°C after heating, but a substantial upper limit is 500 N / 25 mm. The 180° peel strength of the pressure-sensitive adhesive layer (Y2) from SUS at 23°C after heating can be measured by the following method, etc. That is, the pressure-sensitive adhesive sheet is cut to a size of 25 mm wide x 100 mm long, and then the pressure-sensitive adhesive layer (Y1) is lined with a 23 µm thick PET film (e.g., (FE2002) manufactured by Futamura Chemical Co., Ltd.), and the film is pressure-bonded to a SUS plate (a SUS304 plate that has been washed with ethanol and then wiped dry) by applying pressure at 0.1 MPa in an environment of 150°C for 10 minutes, and then air-cooled to prepare a test sample.

[0123] A 180° peel test is performed on the obtained test sample in accordance with JIS Z0237 using a tensile tester (such as "Tensilon" manufactured by ORIENTEC Co., Ltd.) under conditions of 23°C, 50% RH and a peel rate of 300 mm / min, and the adhesive sheet is peeled off from the SUS plate, whereby the 180° peel strength of the adhesive layer (Y2) against SUS at 23°C can be measured.

[0123]

[0123] Examples of a method for adjusting the 180° peel strength from SUS at 23°C after heating of the pressure-sensitive adhesive layer (Y2) include a method of changing the composition of the base polymer (P3) described below of the pressure-sensitive adhesive layer (Y2) or a method of changing the thickness of the pressure-sensitive adhesive layer (Y2).

[0124] The pressure-sensitive adhesive layer (Y2) preferably contains a base polymer (P2). The base polymer (P2) preferably contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, an ethylene-vinyl acetate copolymer, a chloroprene rubber, a nitrile rubber, a polyurethane resin, a polyamide resin, a polyolefin resin, a polyester resin, an epoxy resin, and a silicone resin. Among these, from the viewpoints of easily controlling the probe tack value (described later) and further improving heat resistance, it is more preferable that the base polymer (P2) contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, a chloroprene rubber, a nitrile rubber, a polyurethane resin, a polyamide resin, a polyolefin resin, and a polyester resin.

[0125] The (meth)acrylic copolymer, styrene-based elastomer, and silicone resin in the base polymer (P2) may be the same as those in the base polymer (P1). Specific examples of the (meth)acrylic copolymer in the base polymer (P2) include SK Dyne 1717DT and SK Dyne 1515DT (both manufactured by Soken Chemical & Engineering Co., Ltd.). Specific examples of the styrene-based elastomer in the base polymer (P2) include GR-1160 (manufactured by Big Technos Corporation) and Quintac 3270 (manufactured by Zeon Corporation). Specific examples of the silicone resin in the base polymer (P2) include KR-101-10 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0126] Examples of the ethylene-vinyl acetate copolymer include HM200 (manufactured by Cemedine Co., Ltd.). Examples of the chloroprene rubber include 575F (manufactured by Cemedine Co., Ltd.) and G17 (manufactured by Konishi Co., Ltd.). Examples of the nitrile rubber include 501F (manufactured by Cemedine Co., Ltd.). Examples of the polyurethane resin include SHM107-PUR (manufactured by Seedum Co., Ltd.). Examples of the polyamide resin include SHM301-PAD (manufactured by Seedum Co., Ltd.). Examples of the polyolefin resin include PPET1401SG (manufactured by Toagosei Co., Ltd.). Examples of the polyester resin include PH-413 (manufactured by Nippon Matai Co., Ltd.). Examples of the epoxy resin include 1500 (manufactured by Cemedine Co., Ltd.).

[0127] From the viewpoint of further improving the adhesive strength, the adhesive layer (Y2) preferably further contains a tackifier resin (T3). Examples of the tackifier resin (T3) include those similar to the tackifier resin (T2) described above.

[0128]

[0044] When the base polymer (P2) comprises the (meth)acrylic copolymer, the adhesive layer (Y2) preferably further comprises a curing agent. By including the curing agent in the adhesive layer (Y2), the (meth)acrylic copolymer forms a structure crosslinked by chemical crosslinking, and the adhesive strength of the adhesive sheet obtained is further improved.

[0129] As the curing agent contained in the pressure-sensitive adhesive layer (Y2), for example, the same curing agent as that contained in the pressure-sensitive adhesive layer (Y1) described above can be used.

[0130] The pressure-sensitive adhesive layer (Y2) may contain, as necessary, conventionally known fine particles and additives such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers.

[0131] In the second configuration, the upper limit of the probe tack value of the adhesive layer (Y2) measured under conditions of 23°C, a pressure of 98 gf, a pressure application rate of 100 mm / sec, a pressure application time of 10 seconds, and a peeling rate of 5 mm / sec (hereinafter, sometimes simply referred to as "the probe tack value of the adhesive layer (Y2) at 23°C") is 20 N / 5 mmφ. When the adhesive layer (Y2) has a probe tack value of 20 N / 5 mmφ or less at 23°C, the adhesive layer (Y2) can be prevented from becoming sticky, and the adhesive sheet of the present invention exhibits excellent lamination workability. In the second configuration, the upper limit of the probe tack value of the adhesive layer (Y2) at 23°C is preferably 15 N / 5 mmφ, more preferably 10 N / 5 mmφ. Furthermore, in the first configuration, the upper limit of the probe tack value of the adhesive layer (Y2) at 23°C is preferably 20 N / 5 mmφ.

[0033] When the probe tack value of the adhesive layer (Y2) at 23°C is 20 N / 5 mmφ or less, the adhesive layer (Y2) can be prevented from becoming sticky, and the adhesive sheet of the present invention has better lamination workability. In the first configuration, the upper limit of the probe tack value of the adhesive layer (Y2) at 23°C is more preferably 15 N / 5 mmφ, and even more preferably 10 N / 5 mmφ. The lower limit of the probe tack value of the adhesive layer (Y2) at 23°C is preferably 0.01 N / 5 mmφ. When the probe tack value of the adhesive layer (Y2) at 23°C is 0.01 N / 5 mmφ or more, the adhesive layer (Y2) has an appropriate adhesive force, and from the viewpoint of making it easier to adjust the attachment position of the adhesive sheet of the present invention, the adhesive sheet has better lamination workability. The lower limit of the probe tack value of the pressure-sensitive adhesive layer (Y2) at 23° C. is more preferably 0.1 N / 5 mmφ, and the further lower limit of the probe tack value of the pressure-sensitive adhesive layer (Y2) at 23° C. is 1.0 N / 5 mmφ. The probe tack value of the pressure-sensitive adhesive layer (Y2) at 23° C. can be measured by a probe tack test in accordance with JIS Z 3284.

[0113] Specifically, for example, the pressure-sensitive adhesive sheet of the present invention is cut into a size of 30 mm width × 30 mm length to prepare a test piece, and the pressure-sensitive adhesive layer (Y2) of the prepared test piece is subjected to a probe tack test using a probe tack tester (manufactured by RHESCA, "TAC-2" or the like) under the conditions of 23°C, a pressure of 98 gf, a pressure application rate of 100 mm / sec, a pressure application time of 10 seconds, and a peeling rate of 5 mm / sec, thereby measuring the tackiness.

[0132]

[0133] Examples of a method for adjusting the probe tack value at 23°C of the pressure-sensitive adhesive layer (Y2) include a method for changing the composition or content ratio of the base polymer (P2) or the tackifier resin (T3), and a method for changing the thickness of the pressure-sensitive adhesive (Y2).

[0133] The thickness of the adhesive layer (Y2) is preferably 20 μm at its lower limit and 100 μm at its upper limit. When the thickness of the adhesive layer (Y2) is within this range, the adhesive layer (Y2) can have sufficient adhesive strength. The thickness of the adhesive layer (Y2) is more preferably 25 μm at its lower limit and 80 μm at its upper limit.

[0134] The adhesive sheet of the present invention may have layers other than the adhesive layer (Y1) and the adhesive layer (Y2), if necessary.

[0135]

[0033] The adhesive sheet of the present invention preferably further comprises a base material layer between the adhesive layer (Y1) and the adhesive layer (Y2). When the adhesive sheet of the present invention comprises the base material layer, interlayer cracking is less likely to occur, improving the adhesive strength and preventing component migration between the adhesive layer (Y1) and the adhesive layer (Y2).

[0136] From the viewpoint of substrate strength, the substrate layer preferably contains at least one selected from the group consisting of polyester resin, polyimide resin, polyether resin, polyolefin resin, polyurethane resin, metal, glass fiber, and carbon fiber. Among these, from the viewpoint of higher adhesiveness, heat resistance, and chemical resistance, the substrate layer more preferably contains at least one selected from the group consisting of polyester resin, polyimide resin, polyether resin, glass fiber, and carbon fiber.

[0137] Examples of the polyester resin include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene furanoate (PEF), polylactic acid (PLA), and polybutylene succinate (PBS). Examples of the polyimide resin include Kapton (manufactured by DuPont) and Upilex (manufactured by UBE). Examples of the polyether resin include polyether ether ketone (PEEK) and polyetherimide (PEI). Examples of the polyolefin resin include polyethylene (PE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA). The polyurethane resin is a resin composition composed of a polyisocyanate and a polyol. Examples of the polyisocyanate include 4,4'-diphenylmethane diisocyanate (MDI), and examples of the polyol include polypropylene glycol (PPG). Examples of the metal include SUS, copper, and aluminum. Examples of the glass fiber include glass cloth. Examples of the carbon fiber include carbon cloth.

[0138] Examples of the shape of the substrate layer include a film, a nonwoven fabric, and a woven fabric. Among these, from the viewpoint of the substrate layer exhibiting high anchor strength to the pressure-sensitive adhesive layer (Y1) and the pressure-sensitive adhesive layer (Y2), at least one selected from the group consisting of a nonwoven fabric and a woven fabric is preferred. An example of the nonwoven fabric substrate is G2260-1S (manufactured by Toray International Co., Ltd.). An example of the woven fabric substrate is glass cloth or carbon cloth. A specific example of the glass cloth is KS2770 (manufactured by Nitto Boseki Co., Ltd.), and a specific example of the carbon cloth is C-540 (manufactured by Hagiwara Kogyo Co., Ltd.).

[0139] The thickness of the base material layer is preferably 4 μm at its lower limit and 500 μm at its upper limit. When the thickness of the base material layer is within the above range, the reworkability of the obtained adhesive sheet is further improved. The thickness of the base material layer is more preferably 12 μm at its lower limit and 400 μm at its upper limit, still more preferably 23 μm at its lower limit and 300 μm at its upper limit, and particularly preferably 200 μm at its upper limit.

[0140]

[0033] The method for producing the adhesive sheet of the present invention is not particularly limited, and for example, in the case of an adhesive sheet not having a base layer, the following method can be mentioned. First, a solvent is added to the base polymer (P1), a tackifier resin, and, if necessary, a curing agent, etc. to prepare an adhesive solution (a). The adhesive solution (a) is applied to the release-treated surface of a release PET film, and the solvent in the solution is completely dried and removed to produce a laminate film on which an adhesive layer (Y1) is formed. Similarly, the adhesive solution (b) is applied to the release-treated surface of a release PET film, and the solvent in the solution is completely dried and removed to produce a laminate film on which an adhesive layer (Y2) is formed. The formed adhesive layer (Y1) and adhesive layer (Y2) are then superimposed so that they face each other, and the resulting laminate film is aged for 48 hours in an environment of 40°C and 50% RH, thereby obtaining an adhesive sheet not having a base layer. Alternatively, a substrate is prepared, and a pressure-sensitive adhesive layer (Y1) is superimposed on one surface of the substrate, and a pressure-sensitive adhesive layer (Y2) is superimposed on the other surface of the substrate, and the resulting mixture is cured in an environment of 40°C and 50% RH for 48 hours, thereby obtaining a pressure-sensitive adhesive sheet having a substrate layer.

[0141] The adhesive sheet of the present invention is not particularly limited in its applications, but because it exhibits excellent adhesive strength to fluororesins such as polytetrafluoroethylene even without pretreatment, it is suitable for bonding fluororesins to dissimilar materials for a variety of purposes. More specifically, the various purposes include promoting sliding on friction surfaces, preventing friction between sliding parts, insulating coating, and protecting adherends from high temperatures and chemical solutions. It is particularly suitable for protecting adherends, particularly from chemical solutions. Furthermore, because the adhesive sheet of the present invention has excellent lamination workability, it is particularly suitable for use in bonding lining sheets to can bodies in chemical tanks, and is even more suitable when the chemical tank is a chemical tank for semiconductors or the chemical industry. In other words, a chemical tank to which the adhesive sheet of the present invention is attached is suitable for use in the semiconductor or chemical industry.

[0142]

[0023] A laminate sheet having a fluororesin-containing sheet on the adhesive layer (Y1) side of the adhesive sheet of the present invention also constitutes one aspect of the present invention. Furthermore, a chemical tank having the adhesive sheet of the present invention or the laminate sheet of the present invention attached to the inner surface of a can body, and a method for manufacturing a chemical tank comprising a step of attaching the laminate sheet of the present invention to the inside of the can body of a chemical tank, also constitute one aspect of the present invention. The method for manufacturing a chemical tank of the present invention preferably comprises the steps of: using the adhesive sheet of the present invention, pressing a sheet containing a fluororesin onto the adhesive layer (Y1) to prepare the laminate sheet of the present invention; and attaching the adhesive layer (Y2) of the laminate sheet to the inside of the can body of a chemical tank.

[0143] As the sheet that contains above-mentioned fluororesin, for example, the sheet that contains polytetrafluoroethylene (PTFE), the sheet that contains perfluoroalkoxyalkane (PFA), the sheet that contains perfluoroethylenepropene copolymer (FEP), the sheet that contains ethylenetetrafluoroethylene copolymer (ETFE), the sheet that contains polyvinylidene fluoride (PVDF), the sheet that contains polyvinyl fluoride (PVF), the sheet that contains polychlorotrifluoroethylene (PCTFE), the sheet that contains ethylenechlorotrifluoroethylene copolymer (ECTFE) etc.Among them, the sheet that contains PTFE is preferred because it has excellent heat resistance and chemical resistance.

[0144] In the step of laminating the pressure-sensitive adhesive layer (Y2) of the laminated sheet to the inside of the can body of the chemical solution tank, it is preferable to heat the laminated sheet to bond the pressure-sensitive adhesive layer (Y2) to the inside of the can body.

[0145] In the method for manufacturing a chemical tank of the present invention, the chemical tank is preferably a chemical tank for semiconductors or a chemical tank for the chemical industry.

[0146] According to the present invention, it is possible to provide an adhesive sheet that has excellent adhesive strength to fluororesins such as polytetrafluoroethylene without pre-treating the fluororesins and that has excellent lamination workability. Furthermore, according to the present invention, it is possible to provide a laminated sheet using the adhesive sheet, and a method for manufacturing a chemical liquid tank using the adhesive sheet.

[0147] The following examples will explain the present invention in more detail, but the present invention is not limited to these examples.

[0148] (Preparation of Acrylic Copolymer) (Synthesis Example 1) 100 parts by mass of ethyl acetate was placed in a reactor equipped with a thermometer, a stirrer, and a condenser. The atmosphere was replaced with nitrogen, and the reactor was heated to initiate reflux. 30 minutes after the ethyl acetate boiled, 0.08 parts by mass of azobisisobutyronitrile was added as a polymerization initiator. A monomer mixture of the structural unit monomers shown in Table 1 was added dropwise evenly and gradually over 1 hour and 30 minutes to allow the reaction to proceed. 30 minutes after the completion of the addition, 0.1 parts by mass of azobisisobutyronitrile was added, and the polymerization reaction was continued for another 5 hours. Ethyl acetate was added to the reactor to dilute the mixture while cooling, yielding an acrylic copolymer solution with a solids content of 25% by mass. The resulting acrylic copolymer solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (Waters, 2690 Separations Module), and GPC measurement was performed under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of the acrylic copolymer was measured, and the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) were determined. A GPC KF-806L (Showa Denko KK) was used as the column, and a differential refractometer was used as the detector. The results are shown in Table 1.

[0149] (Synthesis Examples 2 and 3) Acrylic copolymers were obtained in the same manner as in Synthesis Example 1, except that the monomer mixture was changed as shown in Table 1. The results are shown in Table 1.

[0150] The structural unit monomers shown in Table 1 are as follows: BA: n-butyl acrylate, 2EHA: 2-ethylhexyl acrylate, LA: lauryl acrylate, HEA: 2-hydroxyethyl acrylate, AAc: acrylic acid.

[0151]

[0152] (Preparation of Tackifier Resin (T1)) (Synthesis Example A) 50 parts by mass of toluene was placed in a reactor equipped with a thermometer, a stirrer, and a condenser, and the atmosphere was replaced with nitrogen. The reactor was then heated to initiate reflux. After 30 minutes, aluminum chloride (AlCl) was added to the toluene while maintaining the temperature at 75°C. ３2 parts by mass of catechol (pyrocatechol) (n=2) and α-pinene (50 parts by mass in total, the molar ratio is as shown in Table 2) dissolved in 50 parts by mass of toluene was gradually added dropwise to the reactor over 1 hour and 30 minutes to allow the reaction to proceed. After the polymerization reaction had continued for 4 hours, the reactor was cooled while 0.1 parts by mass of pyridine was added to the reactor, and aluminum chloride (AlCl ３ The hydrochloric acid generated from the reaction mixture was neutralized. The precipitate formed by the neutralization was filtered, and the obtained filtrate was subjected to a liquid separation operation. Then, the toluene was evaporated to obtain a solid tackifier resin (T1). Regarding the obtained tackifier resin (T1), １ H-NMR measurement was performed to confirm that the tackifier resin (T1) was a copolymer having a structural unit (A) derived from catechol (pyrocatechol) and a structural unit (B) derived from α-pinene (a copolymer having the structural unit (A) in the main chain skeleton or at the end of the main chain skeleton). A solution of the obtained tackifier resin (T1) dissolved in tetrahydrofuran was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (Waters, 2690 Separations Module), and GPC measurement was performed under conditions of a sample flow rate of 1 mL / min and a column temperature of 40 °C. The polystyrene-equivalent molecular weight of the tackifier resin (T1) was measured, and the weight average molecular weight (Mw) was determined. A GPC KF-802.5L (Showa Denko KK) was used as the column, and a differential refractometer was used as the detector. The results are shown in Table 2.

[0153] (Measurement of Bio-derived Carbon Content of Tackifier Resin (T1)) The bio-derived carbon content of the obtained tackifier resin (T1) was measured in accordance with ASTM D6866-22. The results are shown in Table 2.

[0154] (Synthesis Examples B to C and E) Tackifier resin (T1) was synthesized and measured in the same manner as in Synthesis Example A above (Preparation of tackifier resin (T1)), except that the monomers were changed as shown in Table 2. The results are shown in Table 2.

[0155] Synthesis Example D Preparation of Tackifier Resin (T1) 50 parts by mass of toluene was placed in a reactor equipped with a thermometer, a stirrer, and a condenser, and the atmosphere was replaced with nitrogen. The reactor was then heated to initiate reflux. After 30 minutes, aluminum chloride (AlCl) was added to the toluene while maintaining the temperature at 75°C. ３ 2 parts by mass of 4-vinylbenzoic acid (m=1) and α-pinene (70 parts by mass in total, the molar ratio is as shown in Table 2) dissolved in 50 parts by mass of toluene was gradually added dropwise to the reactor over 1 hour and 30 minutes to allow the reaction to proceed. After the polymerization reaction had been carried out for 4 hours, the reactor was cooled while 0.1 parts by mass of pyridine was added to the reactor, and aluminum chloride (AlCl ３ The hydrochloric acid generated from the reaction mixture was neutralized. The precipitate formed by the neutralization was filtered, and the obtained filtrate was subjected to a liquid separation operation. Then, the toluene was evaporated to obtain a solid tackifier resin (T1). Regarding the obtained tackifier resin (T1), １ H-NMR measurement was performed to confirm that the tackifier resin (T1) was a copolymer having a structural unit (A) derived from 4-vinylbenzoic acid and a structural unit (B) derived from α-pinene (a copolymer having the structural unit (A) in its side chain). A solution of the obtained tackifier resin (T1) dissolved in tetrahydrofuran was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (Waters, 2690 Separations Module), and GPC measurement was performed under conditions of a sample flow rate of 1 mL / min and a column temperature of 40°C. The polystyrene-equivalent molecular weight of the tackifier resin (T1) was measured, and the weight average molecular weight (Mw) was determined. A GPC KF-802.5L (Showa Denko KK) was used as the column, and a differential refractometer was used as the detector. The results are shown in Table 2.

[0156] (Measurement of Bio-derived Carbon Content of Tackifier Resin (T1)) The bio-derived carbon content of the obtained tackifier resin (T1) was measured in accordance with ASTM D6866-22. The results are shown in Table 2.

[0157]

[0158] (Example 1-1) (1) Preparation of adhesive sheet To 100 parts by mass of the solids content of the acrylic copolymer (Synthesis Example 1), 10 parts by mass of tackifier resin (T1) (Synthesis Example A) and 20 parts by mass of tackifier resin (T2) (Pine Crystal KE-359, manufactured by Arakawa Chemical Industries, Ltd.) were added. Furthermore, 30 parts by mass of ethyl acetate (manufactured by Fuji Chemical Industries, Ltd.) and 0.5 parts by mass of an isocyanate-based curing agent (Desmodur L-75, manufactured by Covestro) were added and thoroughly stirred to obtain an adhesive solution (a). The obtained adhesive solution (a) was applied to the release-treated surface of a 75 μm-thick release PET film (SP3000, manufactured by Toyo Cross Co., Ltd.) and dried at 100° C. for 5 minutes to form an adhesive layer (Y1) with a thickness of 50 μm. Furthermore, SHM107-PUR (manufactured by Sheedom Co., Ltd.) was applied to a thickness of 50 μm on the release-treated surface of a separately prepared release PET film having a thickness of 50 μm, to form a pressure-sensitive adhesive layer (Y2). The obtained pressure-sensitive adhesive layer (Y1) and pressure-sensitive adhesive layer (Y2) were overlaid so as to face each other, and then cured by heating at 150°C for 5 minutes. This gave a pressure-sensitive adhesive sheet having pressure-sensitive adhesive layer (Y1) on one surface and pressure-sensitive adhesive layer (Y2) on the other surface.

[0159] (2) Measurement of 180° peel force of pressure-sensitive adhesive layer (Y2) against SUS at 23°C after heating The obtained pressure-sensitive adhesive sheet was cut to a size of 25 mm width × 100 mm length, and then the pressure-sensitive adhesive layer (Y1) was backed with a 23 µm thick PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002"), and then pressure was applied at 0.1 MPa for 10 minutes in an environment of 150°C to pressure-bond it to a SUS plate (a SUS304 plate that had been washed with ethanol and then wiped dry), and then air-cooled to prepare a test sample.

[0123] The obtained test sample was subjected to a 180° peel test in accordance with JIS Z0237 using a tensile tester ("Tensilon" manufactured by ORIENTEC Co., Ltd.) under conditions of 23°C, 50% RH and a peel rate of 300 mm / min, to peel the adhesive sheet from the SUS plate and measure the 180° peel strength of the adhesive layer (Y2) against SUS at 23°C. The results are shown in Table 6.

[0160] (Examples 1-2 to 1-11, 1-17 to 1-28, Comparative Examples 1-3 to 1-5) Using the compositions and thicknesses of the adhesive layer (Y1) and the compositions and thicknesses of the adhesive layer (Y2) as shown in Tables 3 to 5, adhesive sheets were prepared and measurements were carried out in the same manner as in "(1) Preparation of adhesive sheet" in Example 1-1 above. The results are shown in Tables 6 to 8.

[0161] Examples 1-12 to 1-16 Using the compositions and thicknesses shown in Tables 3 and 4, adhesive layers (Y1) and (Y2) were formed in the same manner as in "(1) Preparation of adhesive sheet" in Example 1-1 described above. The substrates shown in Tables 3 and 4 were prepared, and the adhesive layer (Y1) was bonded to one surface of the substrate, and the adhesive layer (Y2) was bonded to the other surface of the substrate, thereby forming an integrated laminate. Subsequently, by heating for 5 minutes in an environment of 150°C, an adhesive sheet having a substrate, an adhesive layer (Y1) on one surface, and an adhesive layer (Y2) on the other surface was obtained. Measurement was carried out in the same manner as in "(2) Measurement of 180° peel strength from SUS at 23°C after heating of adhesive layer (Y2)" in Example 1-1 described above. The results are shown in Tables 6 and 7.

[0162] Comparative Examples 1-1 and 1-2 Using the compositions and thicknesses shown in Table 5, a pressure-sensitive adhesive layer (Y1) or a pressure-sensitive adhesive layer (Y2) was formed in the same manner as in "(1) Preparation of pressure-sensitive adhesive sheet" in Example 1-1 described above, and a 50 μm-thick release PET film was placed on top of the formed pressure-sensitive adhesive layer (Y1) or pressure-sensitive adhesive layer (Y2) so that the release-treated surface faced the film, and the film was cured in an environment of 100°C for 5 minutes, thereby obtaining a pressure-sensitive adhesive sheet having a single layer pressure-sensitive adhesive layer (Y1) or pressure-sensitive adhesive layer (Y2). Measurement was carried out in the same manner as in "(2) Measurement of 180° peel strength from SUS at 23°C after heating of pressure-sensitive adhesive layer (Y2)" in Example 1-1 described above. The results are shown in Table 8.

[0111] In Comparative Examples 1-1 and 1-2, the adhesive sheets were single-layered, and therefore the single-layered adhesive layer could not be classified into an adhesive layer (Y1) and an adhesive layer (Y2). However, in the same measurements as in "(2) Measurement of 180° peel force from SUS at 23°C after heating of adhesive layer (Y2)" in Example 1-1 described above, and in the evaluations described below, the single-layered adhesive layer was the subject of measurement or evaluation.

[0163] <Evaluation> The adhesive sheets obtained in Examples 1-1 to 1-28 and Comparative Examples 1-1 to 1-5 were evaluated by the following methods. The results are shown in Tables 6 to 8.

[0164] (Adhesive strength to fluororesin) The obtained adhesive sheet was cut into a size of 25 mm wide x 100 mm long. The release PET film protecting the adhesive layer (Y1) of the cut adhesive sheet was peeled off, and the adhesive layer (Y1) was pressure-bonded to a polytetrafluoroethylene plate (manufactured by Yodogawa Hutech Co., Ltd., "Yodoflon") having a width of 50 mm, a length of 200 mm, and a thickness of 2 mm using a 2 kg rubber roller, which was rolled back and forth once at a speed of 300 mm / min, to prepare a test sample. The obtained test sample was subjected to a 180° peel test in accordance with JIS Z 0237 using a tensile tester (manufactured by ORIENTEC Co., Ltd., "Tensilon" or the like) under conditions of 23°C, 50% RH, and a peel rate of 300 mm / min, and the adhesive layer (Y1) was peeled from the polytetrafluoroethylene plate, thereby measuring the 180° peel strength of the adhesive layer (Y1) to polytetrafluoroethylene at 23°C. The adhesive strength to the fluororesin of the obtained adhesive layer (Y1) was evaluated based on the following criteria: when the 180° peel strength to polytetrafluoroethylene at 23°C was 10 N / 25 mm or more, it was marked "◎"; when it was 5.0 N / 25 mm or more and less than 10 N / 25 mm, it was marked "◯"; and when it was less than 5.0 N / 25 mm, it was marked "×".

[0165] (Laminating Workability) The obtained adhesive sheet was cut into a size of 25 mm wide x 100 mm long to prepare a test piece. A probe tack test was performed on the adhesive layer (Y2) of the prepared test piece using a probe tack tester (manufactured by RHESCA, "TAC-2") under conditions of 23°C, a pressure of 98 gf, a pressure application rate of 100 mm / sec, a pressure application time of 10 seconds, and a peeling rate of 5 mm / sec, to measure the probe tack value of the adhesive layer (Y2) at 23°C. The laminating workability was evaluated by marking the probe tack value of the obtained adhesive layer (Y2) at 23°C as "◎" when it was 10 N / 5 mmφ or less, "◯" when it was more than 10 N / 5 mmφ and 20 N / 5 mmφ or less, and "×" when it was more than 20 N / 5 mmφ.

[0166]

[0167]

[0168]

[0169]

[0170]

[0171]

[0172] (Example 2-1) (1) Preparation of adhesive sheet To 100 parts by mass of the solids content of the acrylic copolymer (Synthesis Example 1), 10 parts by mass of tackifier resin (T1) (Synthesis Example A) and 20 parts by mass of tackifier resin (T2) (Arakawa Chemical Industries, Ltd., "Pine Crystal KE-359") were added. Furthermore, 30 parts by mass of ethyl acetate (Fuji Chemical Industries, Ltd.) and 0.5 parts by mass of an isocyanate-based curing agent (Covestro, "Desmodur L-75") were added and thoroughly stirred to obtain an adhesive solution (a). The obtained adhesive solution (a) was applied to the release-treated surface of a 75 μm-thick release PET film (Toyo Cross Co., Ltd., "SP3000") and dried at 100°C for 5 minutes to form an adhesive layer (Y1) with a thickness of 50 μm. Furthermore, a pressure-sensitive adhesive layer (Y2) was formed using a pressure-sensitive adhesive solution (b) having a different composition that was prepared by the same method, and the resulting pressure-sensitive adhesive layer (Y1) and pressure-sensitive adhesive layer (Y2) were stacked so as to face each other, and then cured by heating for 48 hours at 40° C. Thereby, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (Y1) on one surface and a pressure-sensitive adhesive layer (Y2) on the other surface was obtained.

[0173] (2) Measurement of 180° peel strength of adhesive layer (Y1) against polytetrafluoroethylene at 23°C The obtained adhesive sheet was cut into a size of 25 mm in width × 100 mm in length, and then a 2 kg rubber roller was used to roll the roller back and forth once at a speed of 300 mm / min to pressure-bond the adhesive layer (Y1) to a polytetrafluoroethylene sheet (manufactured by Yodogawa Hutech Co., Ltd., "Yodoflon") having a thickness of 2 mm, and the resultant was left to stand for 20 minutes in an environment of 23°C and 50% RH to cure, thereby preparing a test sample. The obtained test sample was subjected to a 180° peel test under conditions of 23°C, 50% RH and a peel rate of 300 mm / min using a tensile tester (such as "Tensilon" manufactured by ORIENTEC Co., Ltd.) in accordance with JIS Z 0237, and the 180° peel strength of the pressure-sensitive adhesive layer (Y1) from polytetrafluoroethylene at 23°C was measured by peeling the pressure-sensitive adhesive sheet from the polytetrafluoroethylene sheet. The results are shown in Table 12.

[0174] (3) Measurement of Probe Tack Value of Pressure-Sensitive Adhesive Layer (Y2) at 23°C The obtained pressure-sensitive adhesive sheet was cut into a size of 30 mm width x 30 mm length to prepare a test piece. A probe tack test was performed on the pressure-sensitive adhesive layer (Y2) of the prepared test piece using a probe tack tester (manufactured by RHESCA, "TAC-2" or the like) under conditions of 23°C, a pressure of 98 gf, a pressure application rate of 100 mm / sec, a pressure application time of 10 seconds, and a peeling rate of 5 mm / sec, to measure the probe tack value of the pressure-sensitive adhesive layer (Y2) at 23°C. The results are shown in Table 12.

[0175] (4) Measurement of 180° Peel Force Against SUS at 23°C After Heating of Pressure-Sensitive Adhesive Layer (Y2) The obtained pressure-sensitive adhesive sheet was cut to a size of 25 mm in width × 100 mm in length, and then the pressure-sensitive adhesive layer (Y1) was backed with a 23 µm thick PET film (manufactured by Futamura Chemical Co., Ltd., "FE2002"), and then pressure was applied at 0.1 MPa for 10 minutes in an environment of 150°C to pressure-bond it to a SUS plate (a SUS304 plate that had been washed with ethanol and then wiped dry), followed by air-cooling to prepare a test sample. The obtained test sample was subjected to a 180° peel test under conditions of 23°C, 50% RH and a peel rate of 300 mm / min using a tensile tester (such as "Tensilon" manufactured by ORIENTEC Co., Ltd.) in accordance with JIS Z 0237, and the adhesive sheet was peeled from the SUS plate to measure the 180° peel strength of the adhesive layer (Y2) against SUS at 23°C. The results are shown in Table 12.

[0176] (Examples 2-3, 2-4, 2-6, 2-7, 2-9 to 2-12, 2-18 to 2-23, 2-25, 2-28, 2-29, Comparative Example 2-4) Using the compositions and thicknesses of the pressure-sensitive adhesive layer (Y1) and the compositions and thicknesses of the pressure-sensitive adhesive layer (Y2) as shown in Tables 9 to 11, pressure-sensitive adhesive sheets were prepared and measurements were carried out in the same manner as in "(1) Preparation of pressure-sensitive adhesive sheet" in Example 2-1 above. The results are shown in Tables 12 to 14.

[0177] (Examples 2-2, 2-5, 2-8, 2-13 to 2-17, 2-24, 2-26, 2-27, Comparative Examples 2-5, 2-6) After obtaining a pressure-sensitive adhesive solution (a) in the same manner as in Example 2-1, the pressure-sensitive adhesive solution (Y1) obtained was applied onto a release-treated surface of a release PET film having a thickness of 75 μm, and dried at 100° C. for 5 minutes to form a pressure-sensitive adhesive layer (Y1) having a thickness shown in Tables 9 to 11. Furthermore, a base polymer (P2) shown in Tables 9 to 11 was applied onto a release-treated surface of a separately prepared release PET film having a thickness of 75 μm so that the thickness after drying would be the thickness shown in Tables 9 to 11, to form a pressure-sensitive adhesive layer (Y2). A laminate was obtained by laminating the obtained adhesive layer (Y2) to the adhesive layer (Y1), or by preparing a substrate shown in Tables 9 and 10, laminating the adhesive layer (Y1) to one surface of the substrate, and laminating the adhesive layer (Y2) to the other surface of the substrate. The obtained laminate was heated in a 40°C environment for 48 hours to obtain an adhesive sheet having the adhesive layer (Y1) on one surface and the adhesive layer (Y2) on the other surface. Measurements were performed in the same manner as in "(2) Measurement of the 180° peel strength of the adhesive layer (Y1) from polytetrafluoroethylene at 23°C," "(3) Measurement of the probe tack value of the adhesive layer (Y2) at 23°C," and "(4) Measurement of the 180° peel strength of the adhesive layer (Y2) from SUS at 23°C after heating" in Example 2-1 described above. The results are shown in Tables 12 to 14.

[0178] Comparative Examples 2-1 to 2-3 Using the compositions and thicknesses shown in Table 11, a pressure-sensitive adhesive layer (Y1) or a pressure-sensitive adhesive layer (Y2) was formed in the same manner as in "(1) Production of pressure-sensitive adhesive sheet" in Example 2-1 described above, a release PET film of 75 μm in thickness was attached, and then the resulting film was aged for 48 hours in an environment of 40°C, thereby obtaining a pressure-sensitive adhesive sheet having a single-layer pressure-sensitive adhesive layer (Y1) or a single-layer pressure-sensitive adhesive layer (Y2). Measurements were carried out in the same manner as in "(2) Measurement of the 180° peel strength of the pressure-sensitive adhesive layer (Y1) from polytetrafluoroethylene at 23°C," "(3) Measurement of the probe tack value of the pressure-sensitive adhesive layer (Y2) at 23°C," and "(4) Measurement of the 180° peel strength of the pressure-sensitive adhesive layer (Y2) from SUS at 23°C after heating" in Example 2-1 described above. The results are shown in Table 14.

[0111] In Comparative Examples 2-1 to 2-3, the adhesive sheets were single-layered, and therefore the single-layered adhesive layer could not be classified into an adhesive layer (Y1) and an adhesive layer (Y2). However, in measurements similar to "(2) Measurement of the 180° peel force of the adhesive layer (Y2) from SUS at 23°C after heating," "(3) Measurement of the probe tack value of the adhesive layer (Y2) at 23°C," and "(4) Measurement of the 180° peel force of the adhesive layer (Y2) from SUS at 23°C after heating" in Example 2-1 described above, and in the evaluations described below, the single-layered adhesive layer was the subject of measurement or evaluation.

[0179] <Evaluation> The adhesive sheets obtained in Examples 2-1 to 2-29 and Comparative Examples 2-1 to 2-6 were evaluated by the following methods. The results are shown in Tables 12 to 14.

[0180] (Laminating workability) The obtained adhesive sheet was cut into a size of 25 mm wide x 100 mm long. The release PET film protecting the adhesive layer (Y1) of the cut adhesive sheet was peeled off, and the adhesive layer (Y1) was pressure-bonded to a 50 mm wide x 200 mm long x 2 mm thick polytetrafluoroethylene plate (manufactured by Yodogawa Hutech Co., Ltd., "Yodoflon") by using a 2 kg rubber roller and moving it back and forth once at a speed of 300 mm / min, thereby producing a laminate. Furthermore, the release PET film protecting the adhesive layer (Y2) of the obtained laminate was peeled off, and the adhesive layer (Y2) was attached by pressure bonding using a 5 mmφ SUS probe at 23°C, a pressure of 98 gf, a pressure rate of 100 mm / sec, and a pressure time of 10 seconds. After leaving to stand for 10 minutes in an environment of 23°C and 50% RH, the adhesive layer (Y2) was peeled off from the SUS at a peeling speed of 5 mm / sec, and the surface of the adhesive layer (Y2) and the adhesive surface between the polytetrafluoroethylene and the adhesive layer (Y1) were observed visually and with an optical microscope. The evaluation of lamination workability was carried out by assigning "◎" to cases where the observed surface of the adhesive layer (Y2) was not roughened and did not peel off from the polytetrafluoroethylene, "◯" to cases where the surface of the adhesive layer (Y2) was roughened but the adhesive layer (Y1) did not peel off from the polytetrafluoroethylene, and "×" to cases where the surface of the adhesive layer (Y2) was roughened and the adhesive layer (Y1) peeled off from the polytetrafluoroethylene during the lamination operation.

[0181]

[0182]

[0183]

[0184]

[0185]

[0186]

[0187] According to the present invention, it is possible to provide an adhesive sheet that has excellent adhesive strength to fluororesins such as polytetrafluoroethylene without pre-treating the fluororesins and that has excellent lamination workability. Furthermore, according to the present invention, it is possible to provide a laminated sheet using the adhesive sheet, and a method for manufacturing a chemical liquid tank using the adhesive sheet.

Claims

1. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (Y1) on one surface and a pressure-sensitive adhesive layer (Y2) on the other surface, characterized in that the pressure-sensitive adhesive sheet has at least one configuration selected from the group consisting of the following first and second configurations. First configuration: The pressure-sensitive adhesive layer (Y1) contains a base polymer (P1) and a tackifier resin, The base polymer (P1) contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin, The pressure-sensitive adhesive layer (Y2) is a hot melt pressure-sensitive adhesive layer. Second configuration: The pressure-sensitive adhesive layer (Y1) has a 180° peel strength against polytetrafluoroethylene at 23°C of 5.0 N / 25 mm or more, The pressure-sensitive adhesive layer (Y2) has a probe tack value of 20 N / 5 mmφ or less measured under conditions of 23°C, a pressure of 98 gf, a pressure speed of 100 mm / sec, a pressure time of 10 seconds, and a peel speed of 5 mm / sec.

2. An adhesive sheet according to claim 1, having said first configuration, wherein said adhesive layer (Y1) has a 180° peel strength against polytetrafluoroethylene at 23° C. of 2.5 N / 25 mm or more.

3. The adhesive sheet according to claim 1, having the second configuration, wherein the adhesive layer (Y1) contains a base polymer (P1) and a tackifier resin, and the base polymer (P1) contains at least one selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin.

4. The adhesive sheet according to claim 1, 2 or 3, wherein the softening point of the adhesive layer (Y2) is 40° C. or higher.

5. The adhesive sheet according to claim 1, 2, 3 or 4, wherein the adhesive sheet has a 180° peel strength against SUS at 23°C of 10 N / 25 mm or more when the adhesive layer (Y2) side is pressed against SUS at a pressure of 0.1 MPa for 10 minutes in an environment of 150°C.

6. The adhesive sheet according to claim 1, 2, 3, 4 or 5, wherein the adhesive layer (Y2) contains a base polymer (P2), and the base polymer (P2) contains at least one selected from the group consisting of (meth)acrylic copolymers, styrene-based elastomers, ethylene-vinyl acetate copolymers, chloroprene rubber, nitrile rubber, polyurethane resins, polyamide resins, polyolefin resins, polyester resins, epoxy resins, and silicone resins.

7. The adhesive sheet according to claim 1, 2, 3, 4, 5 or 6, which has the first structure or the second structure, and wherein the adhesive layer (Y1) contains a tackifier resin, the tackifier resin comprising a tackifier resin (T1) having at least one structural unit (A) selected from the group consisting of structural unit (A-1), structural unit (A-1'), structural unit (A-2), structural unit (A-2'), structural unit (A-3), structural unit (A-3'), structural unit (A-4) and structural unit (A-4') represented by the following formula: In the formula, R １ ~R ７ each represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. n and l each represent an integer of 2 or more and 4 or less, and n' and l' each represent an integer of 2 or more and 5 or less. m and k each represent an integer of 1 or more and 4 or less, and m' and k' each represent an integer of 1 or more and 5 or less. * represents a linking portion.

8. The adhesive sheet according to claim 7, wherein the tackifier resin (T1) further comprises a structural unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers.

9. A pressure-sensitive adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7 or 8, having the first configuration or the second configuration, and wherein the pressure-sensitive adhesive layer (Y1) contains a tackifier resin, and the tackifier resin includes at least one tackifier resin (T2) selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum-based resins.

10. The adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, wherein the adhesive layer (Y1) is not a hot melt adhesive layer.

11. The adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the adhesive layer (Y1) has a thickness of 25 μm or more and 1000 μm or less.

12. The adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, further comprising a substrate layer between the adhesive layer (Y1) and the adhesive layer (Y2).

13. The adhesive sheet according to claim 12, wherein the base layer contains at least one material selected from the group consisting of polyester resin, polyimide resin, polyether resin, polyolefin resin, polyurethane resin, metal, glass fiber, and carbon fiber.

14. The adhesive sheet according to claim 12 or 13, wherein the base layer is made of at least one material selected from the group consisting of nonwoven fabrics and woven fabrics.

15. The adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14, which is used to join a lining sheet to a tank body in a chemical tank.

16. The adhesive sheet according to claim 15, wherein the liquid chemical tank is a liquid chemical tank for semiconductors or a liquid chemical tank for the chemical industry.

17. A laminate sheet comprising a sheet containing a fluororesin on the adhesive layer (Y1) side of the adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16.

18. A chemical tank having an adhesive sheet according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 or a laminated sheet according to claim 17 attached to the inner surface of a can body.

19. A method for manufacturing a liquid chemical tank, comprising the step of laminating the laminated sheet according to claim 17 to the inside of a can body of the liquid chemical tank.

20. A method for manufacturing a chemical tank as set forth in claim 19, comprising the steps of: using an adhesive sheet as set forth in claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16, and pressing a sheet containing a fluororesin onto the adhesive layer (Y1) to produce a laminate sheet as set forth in claim 17; and bonding the adhesive layer (Y2) of the laminate sheet to the inside of a can body of a chemical tank.

21. A method for manufacturing a chemical tank as described in claim 20, wherein in the step of bonding the adhesive layer (Y2) of the laminated sheet to the inside of a can body of the chemical tank, the laminated sheet is heated to bond the adhesive layer (Y2) to the inside of the can body.

22. The method for manufacturing a chemical tank according to claim 19, 20 or 21, wherein the chemical tank is a chemical tank for semiconductors or a chemical tank for the chemical industry.

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