Adhesive sheet, multilayer sheet, chemical liquid tank, and method for producing chemical liquid tank

Abstract

The present invention makes it possible to provide an adhesive sheet, one surface of which having excellent adhesion to a fluororesin such as a polytetrafluoroethylene even if a pre-treatment is not performed on the fluororesin, and the other surface of which making it possible to suppress peeling of a base material. The present invention can also provide a multilayer sheet which comprises the adhesive sheet. The present invention can also provide a chemical liquid tank to which the adhesive sheet or the multilayer sheet is attached. The present invention can also provide a method for producing a chemical liquid tank using the multilayer sheet or the adhesive sheet. The present invention is an adhesive sheet which has a base material and an adhesive layer (Y1) on one surface of the base material, wherein: the base material is composed of at least one material that is selected from the group consisting of a nonwoven fabric, a glass cloth, a carbon cloth, a metal mesh, and a foam having an open cell structure; and the adhesive sheet has a 180° peel strength of 5.0 N / 25 mm or more on the adhesive layer (Y1) side with respect to a polytetrafluoroethylene at 23°C.

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 laminate sheet having the adhesive sheet. The present invention further relates to a chemical tank having the adhesive sheet or the laminate sheet attached thereto. The present invention also relates to a method for manufacturing a chemical tank using the laminate sheet or the adhesive sheet.

[0002] Conventionally, adhesive sheets have been widely used to fix various components. Specifically, adhesive sheets are used, for example, to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module to a display panel module. Adhesive sheets used to fix such components are required to have not only high adhesiveness but also functions 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, lining tanks with fluororesin bonded to the tank body are often used. Traditionally, fluororesin has been bonded to the tank body by applying adhesives such as chloroprene rubber or epoxy resin to the fluororesin and the tank body, respectively, followed by heat and pressure bonding. However, these adhesives cannot achieve sufficient adhesive strength without pre-treating the fluororesin surface. To improve adhesive strength, the fluororesin is typically pre-treated, typically by chemical etching. Such pre-treatments are not only expensive but also pose problems such as reduced quality and safety and environmental impacts. Therefore, an alternative adhesive sheet that can be used without pre-treatment is desired.

[0006] When an adhesive sheet is used to bond a fluororesin to a can body, using a non-support sheet that does not have a substrate results in poor bonding workability between the fluororesin and the adhesive sheet, and the sheet may float from the interface of the fluororesin during bonding work, so it is necessary to use a support sheet that has a substrate to ensure bonding workability.Methods for bonding a can body and a fluororesin using a support sheet that has a substrate include: (1) a method in which a single-sided sheet having an adhesive layer on one side is used to prepare a laminated sheet by bonding the fluororesin to the adhesive layer of the single-sided sheet, and then the can body and the substrate of the single-sided sheet in the laminated sheet are bonded with an adhesive, and (2) a method in which a double-sided sheet having adhesive layers on both sides is used to bond the can body and the fluororesin at once.

[0007] However, in both methods (1) and (2), the adhesive strength at the interface between the adhesive that bonds the can body and the can body is strong. Therefore, when a film substrate, typically a PET film, which is commonly used as a substrate for adhesive sheets, is used, the adhesive strength at the interface between the adhesive that bonds the can body and the substrate decreases, and peeling may occur at the interface between the adhesive that bonds the can body and the substrate.

[0008] The present invention provides an adhesive sheet that has excellent adhesion to fluororesins such as polytetrafluoroethylene on one side without pretreatment, and that can suppress peeling of the substrate on the other side.The present invention also relates to a laminate sheet having the adhesive sheet.Furthermore, the present invention provides a chemical tank having the adhesive sheet or the laminate sheet attached thereto.Furthermore, the present invention provides a method for manufacturing a chemical tank using the laminate sheet or the adhesive sheet.

[0009] Disclosure 1 relates to an adhesive sheet having a substrate and an adhesive layer (Y1) on one side of the substrate, wherein the substrate is composed of at least one material selected from the group consisting of nonwoven fabric, glass cloth, carbon cloth, metal mesh, and foams having an open-cell structure, and wherein the adhesive sheet has a 180° peel strength of 5.0 N / 25 mm or more at 23°C from polytetrafluoroethylene on the side of the adhesive layer (Y1). Disclosure 2 relates to the adhesive sheet of Disclosure 1, further comprising an adhesive layer (Y2) on the other side of the substrate. Disclosure 3 relates to the adhesive sheet of Disclosure 1 or 2, wherein the adhesive layer (Y1) contains a base polymer (P1) and a tackifier resin, and the base polymer (P1) comprises at least one material selected from the group consisting of a (meth)acrylic copolymer, a styrene-based elastomer, and a silicone resin. Disclosure 4 relates to the adhesive sheet of Disclosure 3, wherein the tackifier resin comprises 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: Disclosure 5 relates to the adhesive sheet of Disclosure 4, 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. Disclosure 6 relates to the adhesive sheet of Disclosure 3, 4, or 5, wherein 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. Disclosure 7 is the adhesive sheet of Disclosure 1, 2, 3, 4, 5, or 6, wherein the adhesive layer (Y1) has a thickness of 25 μm or more and 1000 μm or less. Disclosure 8 is the adhesive sheet of Disclosure 2, wherein the adhesive sheet has a probe tack value of 2000 gf / 5 mmφ or less on the adhesive layer (Y2) side, measured under conditions of 23°C, a pressure of 98 gf, a pressure rate of 100 mm / sec, a pressure time of 10 seconds, and a peel rate of 5 mm / sec. Disclosure 9 is the adhesive sheet of Disclosure 2 or 8, wherein the adhesive layer (Y2) has a thickness of 20 μm or more and 1000 μm or less.Disclosure 10 is the adhesive sheet of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, or 9, used for lining the can body of a chemical tank for semiconductors or a chemical tank for the chemical industry. Disclosure 11 is a laminate sheet of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, having a sheet containing a fluororesin on a surface of the adhesive layer (Y1) different from the surface that contacts the substrate. Disclosure 12 is the laminate sheet of Disclosure 11, used to protect an adherend. Disclosure 13 is the laminate sheet of Disclosure 12, used to protect an adherend from chemical solutions. Disclosure 14 is a chemical tank having the adhesive sheet of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, or 9, or the laminate sheet of Disclosures 10, 11, 12, or 13, attached to the inner surface of a can body. Disclosure 15 is a method for manufacturing a chemical liquid tank for semiconductors or a chemical liquid tank for the chemical industry, comprising a step of attaching to the inner surface of a can body of the chemical liquid tank the laminate sheet of Disclosure 10, 11, 12, or 13. Disclosure 16 is a method for manufacturing a chemical liquid tank for semiconductors or a chemical liquid tank for the chemical industry, comprising a laminate sheet production step of pressing a sheet containing a fluororesin to the adhesive layer (Y1) using the adhesive sheet of Disclosure 2, 8, or 9, and a step of attaching the adhesive layer (Y2) of the laminate sheet to the inner surface of a can body of the chemical liquid tank.

[0010]

[0011]

[0012]

[0013]

[0014] 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.

[0015] The present inventors investigated an adhesive sheet having a substrate and an adhesive layer, in which the 180° peel strength of the adhesive layer to polytetrafluoroethylene is set within a specific range, and in which a specific type of substrate is used as the substrate. As a result, they discovered that an adhesive sheet can be obtained that has excellent adhesion to fluororesins such as polytetrafluoroethylene on one side without pretreatment of the fluororesin, and that can suppress peeling of the substrate on the other side, thereby completing the present invention. Note that in this specification, "adhesion" not only refers to a permanent adhesion phenomenon, but also has the meaning of "stickiness," which is a temporary adhesion phenomenon.

[0016] The adhesive sheet of the present invention has a substrate. By having a substrate, the adhesive sheet obtained has excellent lamination workability.

[0017] The substrate is composed of at least one material selected from the group consisting of nonwoven fabric, glass cloth, carbon cloth, metal mesh, and open-cell foam. By using at least one material selected from the group consisting of nonwoven fabric, glass cloth, carbon cloth, metal mesh, and open-cell foam, the anchor strength of the substrate is improved, preventing delamination of the substrate, resulting in high-strength adhesion. Furthermore, in the case of a single-sided adhesive sheet, air may be generated at the adhesive surface when the adhesive sheet is pressed against the adhesive layer that adheres the substrate to the can body, which can cause the adhesive to easily delaminate from the substrate. By using at least one material selected from the group consisting of nonwoven fabric, glass cloth, carbon cloth, metal mesh, and open-cell foam, the substrate has a uniform surface structure and provides air passages, improving air release properties that prevent air generation as described above. This prevents delamination of the substrate even when an adhesive is applied to the substrate. Among these, the substrate is preferably composed of glass cloth, carbon cloth, or metal mesh from the standpoints of heat resistance and chemical resistance.

[0018] Examples of the nonwoven fabric include G2260-1S (manufactured by Toray International Co., Ltd.). Examples of the glass cloth include KS2770 (manufactured by Nitto Boseki Co., Ltd.). Examples of the carbon cloth include C-540 (manufactured by Hagiwara Kogyo Co., Ltd.). Examples of the metal mesh include mesh from Naslon (manufactured by Nippon Seisen Co., Ltd.). Examples of the foam having an open-cell structure include Poron SR-S-70P (manufactured by Inoac Corporation).

[0019] The thickness of the substrate is preferably 4 μm at the lower limit and 500 μm at the upper limit. By having the thickness of the substrate within the above range, the interlayer strength of the resulting adhesive sheet is further improved. The thickness of the substrate is more preferably 12 μm at the lower limit and 300 μm at the upper limit, and even more preferably 23 μm at the lower limit and 200 μm at the upper limit.

[0020] The preferred upper limit of the heat shrinkage rate of the substrate is 5%. A heat shrinkage rate of 5% or less of the substrate makes it less likely to undergo dimensional changes during actual use, and less likely to peel after application. A more preferred upper limit of the heat shrinkage rate of the substrate is 3%, an even more preferred upper limit is 0.5%, and 0% is most preferred. The heat shrinkage rate of the substrate is measured, for example, by the following method. That is, the substrate is cut into a 10 cm square to prepare a test piece, and the prepared test piece is placed in an oven at 120°C and heated for 10 minutes. The heated test piece is then air-cooled to room temperature, and the length of the side of the test piece is measured, and the heat shrinkage rate can be measured using the following formula (1). In the following formula (1), the side lengths in "the length of one side of the test piece before heating" and "the length of one side of the test piece after heating" refer to the length of the same side. Heat shrinkage rate (%) = ((length of one side of the test piece before heating) - (length of one side of the test piece after heating)) / (length of one side of the test piece before heating) × 100 (1)

[0021] The adhesive sheet of the present invention has an adhesive layer (Y1) on one surface. The adhesive layer (Y1) has a lower limit of 180° peel strength from polytetrafluoroethylene at 23°C of 5.0 N / 25 mm. When the adhesive layer (Y1) has a 180° peel strength from polytetrafluoroethylene at 23°C of 5.0 N / 25 mm or more, the adhesive sheet of the present invention has excellent adhesive strength to fluororesins. The lower limit of the 180° peel strength from polytetrafluoroethylene at 23°C of the adhesive layer (Y1) is preferably 7.0 N / 25 mm, more preferably 10 N / 25 mm. There is no particular upper limit to the 180° peel strength from polytetrafluoroethylene at 23°C of the adhesive layer (Y1), but approximately 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 pressed onto a 2 mm thick polytetrafluoroethylene sheet (Yodogawa Hutec Co., Ltd., "Yodoflon" or the like) using a 2 kg rubber roller, by moving it back and forth once at a speed of 300 mm / min. 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. The obtained test sample is subjected to a 180 ° peel test in accordance with JIS Z0237 using a tensile tester (ORIENTEC Co., Ltd., "Tensilon" or the like) under conditions of 23 ° C., 50% RH, and a peel speed of 300 mm / min. The adhesive sheet (Y1) is peeled from the polytetrafluoroethylene sheet, and the 180 ° peel strength of the adhesive layer (Y1) against polytetrafluoroethylene at 23 ° C. can be measured.

[0022] Examples of methods for adjusting the 180° peel strength of the adhesive layer (Y1) against polytetrafluoroethylene at 23°C within the above-mentioned range include a method of changing the type or structural unit of the base polymer (P1) contained in the adhesive layer (Y1) (for example, a method of changing the copolymerization ratio or composition of the base polymer (P1)), a method of adjusting the type or content of the tackifier resin contained in the adhesive layer (Y1), a method of increasing the thickness of the adhesive layer (Y1), a method of changing the substrate, and the like.

[0023] The adhesive layer (Y1) preferably contains a base polymer (P1). Examples of the base polymer (P1) include base polymers containing a (meth)acrylic copolymer, a styrene-based elastomer, a silicone resin, etc. Among these, the base polymer (P1) preferably contains at least one selected from the group consisting of a (meth)acrylic copolymer and a styrene-based elastomer, because this allows for a wide range of design possibilities for the adhesive layer (Y1) and enables the adhesive layer (Y1) to exhibit strong adhesive strength. In this specification, the term "base polymer" refers to a polymer that accounts for 50% by mass or more of the polymer contained in the adhesive layer and has a weight-average molecular weight of 50,000 or more.

[0024] The (meth)acrylic copolymer preferably has a structural unit derived from an alkyl (meth)acrylate. The alkyl (meth)acrylate preferably contains 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. By having the (meth)acrylic copolymer have 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, thereby further improving the adhesive strength of the adhesive layer (Y1) to the fluororesin. In this specification, "(meth)acrylate" means acrylate or methacrylate. In addition, in this specification, "alkyl(meth)acrylate having an alkyl group at the ester terminal" means a (meth)acrylate in which an alkyl group is bonded to the oxygen atom of the ester bond.

[0025] Examples of alkyl(meth)acrylates 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 of the adhesive sheet (particularly the adhesive strength to fluororesins). 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.

[0026] 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 improved flexibility of the adhesive layer (Y1), thereby further improving 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. Furthermore, 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 adhesive layer (Y1), the upper limit is preferably 99 mass %.

[0027] 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, resulting in an appropriate reduction in the shear storage modulus at 25°C of the adhesive layer (Y1) 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 6 to 8 carbon atoms at the ester terminal is 85% by mass, and an even more preferred lower limit is 90% by mass. Furthermore, from the viewpoint of the cohesive strength of the bulk of the adhesive layer (Y1), the upper limit of the structural units derived from alkyl (meth)acrylate having an alkyl group having from 4 to 12 carbon atoms at the ester terminal is preferably 99.5 mass%, and more preferably 99 mass%.

[0028] The alkyl (meth)acrylate may contain alkyl (meth)acrylates other than the alkyl (meth)acrylates having an alkyl group having from 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 in combination of two or more.

[0029] The (meth)acrylic copolymer preferably further contains a structural unit derived from a polar functional group-containing monomer. By containing a structural unit derived from a polar functional group-containing monomer in the (meth)acrylic copolymer, the bulk cohesive strength of the adhesive layer (Y1) is increased, and the adhesive strength of the resulting adhesive sheet is further improved.

[0030] 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 carboxy group and a hydroxyl group are more preferred because they contribute 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 structural units derived from a carboxyl group-containing (meth)acrylate and structural units derived from a hydroxyl group-containing (meth)acrylate. Examples of the carboxyl group-containing monomer include (meth)acrylic acid. Examples of the hydroxyl group-containing monomer include 4-hydroxybutyl (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.

[0031] The content of the structural units derived from the carboxyl 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. By having the content of the structural units derived from the carboxyl group-containing monomer within this range, the bulk cohesive strength of the adhesive layer (Y1) can be appropriately adjusted, so that the adhesive sheet obtained has superior adhesive strength. The content of the structural units derived from the carboxyl group-containing monomer is more preferably 0.05% by mass at the lower limit and 2.0% by mass at the upper limit.

[0032] 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. By having the content of the structural units derived from the hydroxyl group-containing monomer within this range, the bulk cohesive strength of the adhesive layer (Y1) can be appropriately adjusted, resulting in an adhesive sheet with 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.

[0033] The total content of the structural units derived from the polar functional group-containing monomer in the (meth)acrylic copolymer is preferably 0.01% by mass at the lower limit and 6.0% by mass at the upper limit. By having the total content of the structural units derived from the polar functional group-containing monomer within this range, the bulk cohesive strength of the adhesive layer (Y1) can be appropriately adjusted, resulting in an adhesive sheet with superior adhesive strength. The more preferred lower limit of the total content of the structural units derived from the polar functional group-containing monomer is 0.1% by mass, and the more preferred upper limit is 3.0% by mass.

[0034] 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 such other 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 such other monomers include various monomers commonly used in acrylic polymers, such as vinyl carboxylates such as vinyl acetate and styrene. These other monomers may be used alone or in combination of two or more.

[0035] The weight-average molecular weight (Mw) of the (meth)acrylic copolymer preferably has a lower limit of 50,000 and an upper limit of 1,600,000. When the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 50,000 or more, the bulk cohesive strength of the adhesive layer (Y1) is improved, and the adhesive strength of the resulting adhesive sheet is further improved. When the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 1,600,000 or less, the adhesiveness 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 100,000 and an upper limit of 1,200,000.

[0036] 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 fluororesins 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 9.0, even more preferably 8.0, and even more preferably 7.0.

[0037] In this specification, the weight average molecular weight (Mw) and number average molecular weight (Mn) refer to the weight 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 is 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 measured using the weight average molecular weight (Mw) and number average molecular weight (Mn) thus obtained.

[0038] The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the (meth)acrylic copolymer can be adjusted to fall within the above ranges by, for example, adjusting the composition, polymerization method, polymerization conditions, etc. of the (meth)acrylic copolymer.

[0039] 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, the shear storage modulus at 25°C of the adhesive layer (Y1) described below can be easily adjusted to an appropriate range, thereby resulting in an adhesive sheet with superior adhesive strength to fluororesins. The glass transition temperature (Tg) of the (meth)acrylic copolymer is more preferably -60°C in lower limit and more preferably -40°C in upper limit. In this specification, the glass transition temperature can be the value obtained in one run when measured using a differential scanning calorimeter (e.g., "SII Exstar 6000 / DSC 6220" manufactured by Hitachi High-Tech Science Corporation) under conditions of a nitrogen atmosphere and a heating rate of 10°C / min.

[0040] The polymerization method for synthesizing the (meth)acrylic copolymer may be a conventionally known method in which monomers from which the above-mentioned structural units are derived are subjected to a radical reaction in the presence of a polymerization initiator, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization, etc. Among these, solution polymerization is preferred because of its ease of synthesis.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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). Of these, SIS block copolymers and SBS block copolymers are preferred, with SIS block copolymers being more preferred, because the resulting adhesive sheet is more 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.

[0047] The styrene-based elastomer may contain, in addition to a triblock copolymer of the block derived from the styrene-based monomer and the block derived from the conjugated diene-based monomer, a diblock copolymer of the block derived from the styrene-based monomer and the block derived from the conjugated diene-based monomer. The preferred lower limit of the content of the diblock copolymer in the styrene-based elastomer (hereinafter sometimes referred to as the "diblock ratio") is 50% by mass. A diblock ratio of 50% by mass or more improves the adhesion of the adhesive layer (Y1) to the 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. Furthermore, 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).

[0048] 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 adhesive layer (Y1) does not become too hard, and the adhesion to the adherend is increased, further improving the adhesive strength of the resulting adhesive sheet. 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 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.

[0049] 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.

[0050] An example of the silicone resin is KR-3700 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0051] The preferred lower limit of the content of the base polymer (P1) in the adhesive layer (Y1) is 30% by mass, and the preferred upper limit is 99.5% by mass. When the content of the base polymer (P1) is within the above range, the adhesive layer (Y1) has improved adhesive strength to fluororesins. The more preferred lower limit of the content of the base polymer (P1) is 40% by mass, and the more preferred upper limit is 99% by mass, and the even more preferred lower limit is 50% by mass, and the even more preferred upper limit is 95% by mass.

[0052] The adhesive layer (Y1) preferably contains a 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 containing the tackifier resin (T1) in the adhesive layer (Y1), the adhesive layer (Y1) can exhibit higher adhesive strength, particularly high adhesive strength to adherends with low polarity (e.g., fluororesins, etc.). 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'), because this can greatly improve the interaction with the adherend and further increase the adhesive strength to the adherend, 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. Furthermore, since it is easy to use monomers containing biological materials, as described below, as monomers constituting the structural unit (A-1) and the structural unit (A-1'), this is preferable from the perspective of conserving petroleum resources. Furthermore, when the base polymer (P1) is a (meth)acrylic copolymer, the tackifier resin (T1) has an appropriate polarity, which results in better compatibility with the (meth)acrylic copolymer.

[0053] 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.

[0054] 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 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 have been substituted with a polar functional group such as those 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 have been substituted with a polar functional group such as those described above.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] In the structural unit (A), n and l are each an integer of 2 or greater and 4 or less, and n' and l' are each an integer of 2 or greater and 5 or less, but are not particularly limited thereto. 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).

[0062] In the structural unit (A), m and k are each an integer of 1 or greater and 4 or less, and m' and k' are each an integer of 1 or greater and 5 or less, but are not particularly limited thereto. From the viewpoint of ease of availability of raw materials, m, k, m', and k' are preferably 1, 2, or 3, and it is more preferable that m, k, m', and k' are 1, since this can further increase the adhesive strength of the adhesive layer (Y1).

[0063] More 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.

[0064] More 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.

[0065] More 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.

[0066] More 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.

[0067] 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.

[0068] 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, the adhesive strength of the adhesive layer (Y1) can be further increased by incorporating the tackifier resin (T1) into the adhesive layer (Y1). 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, the adhesive strength of the adhesive layer (Y1) can be further increased by incorporating the tackifier resin (T1) into the adhesive layer (Y1). 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.

[0069] 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. The tackifier resin (T1) containing the structural unit (B) can further enhance the adhesive strength of the adhesive layer (Y1). Furthermore, from the viewpoint of improving the compatibility between the tackifier resin (T1) and the base polymer, a structural unit derived from a terpene monomer is preferred. Since a structural unit derived from a terpene monomer contains an aliphatic hydrocarbon group having an unsaturated double bond, the tackifier resin (T1) containing a structural unit derived from a terpene monomer improves the compatibility between the tackifier resin (T1) and the base polymer (P1), thereby preventing a decrease in the adhesive strength of the adhesive layer (Y1) due to poor compatibility.

[0070] 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 enhance 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 (P1), a vinyl monomer that does not have a structure containing two or more aromatic rings in one molecule (e.g., a naphthalene structure, an anthracene structure, a biphenyl structure, an anthraquinone structure, a benzophenone structure, etc.) is preferred. Examples of the vinyl monomer that does not have 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 increase the adhesive strength of the adhesive layer (Y1). These monomers (b) may be used alone or in combination of two or more.

[0071] 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.

[0072] 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 the suitable physical properties required for 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 particularly, further increasing the adhesive strength to adherends with low polarity. The more preferred lower limit of the content of the structural unit (B) is 50 mol%, and the more preferred upper limit is 90 mol%.

[0073] 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: 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 adhesive strength of the adhesive layer (Y1), and can particularly further increase the adhesive strength even to adherends with low polarity.

[0074]

[0075] 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.

[0076] 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 it is a copolymer, the structural units (A) and (B) may be copolymerized randomly, or may be copolymerized with regularity or periodicity, for example, in which each of them forms a block segment and then the block segments are bonded to each other.

[0077] 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 adhesive strength of the adhesive layer (Y1).

[0078] 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 two or more types may be used in combination.

[0079] 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 700, 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).

[0080] 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 even more preferably 5,000 MPa. The Young's modulus of the tackifier resin (T1) at 25°C can be measured by a tensile test using a tensile tester (e.g., "Tensilon" manufactured by ORIENTEC Co., Ltd.) at a tension speed of 200 mm / min, a gripper distance of 15 mm, and 25°C. The measurement sample in this case can be obtained, for example, by filling the tackifier resin (T1) into a mold having a size of 10 × 50 mm, melting it at a temperature 100°C higher than the glass transition temperature, and preparing a test piece having a thickness of 1 mm.

[0081] 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), the composition and content of the structural unit (A) and the structural unit (B) in the tackifier resin (T1), and the like.

[0082] 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.

[0083] 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 more easily 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), particularly to an adherend 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."

[0084] 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.

[0085] The tackifier resin (T1) also includes hydrogenated products of the compounds described above. The hydrogenated products are compounds in which the carbon-carbon double bonds present in the tackifier resin (T1) are at least partially saturated by hydrogenation. That is, the 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 suitable for use as the tackifier resin to be incorporated into the adhesive layer (Y1), and can increase the adhesive strength of the adhesive layer (Y1), particularly to adherends with low polarity.

[0086] 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]).

[0087] 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:

[0088]

[0089]

[0090]

[0091]

[0092] 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.

[0093] 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.

[0094] 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 higher yield of copolymer. ３ ) is preferred.

[0095] 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.

[0096]

[0097] In the formula, s and t each represent an integer of 1 or more, and * represents a linking moiety.

[0098] 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]).

[0099] 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.

[0100] 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).

[0101] The tackifier resin (T1) can increase the adhesive strength of the adhesive layer (Y1) even in a small amount compared to 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 30 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 increased, particularly to adherends with low polarity (e.g., fluororesins). When the content of the tackifier resin (T1) is 30 parts by mass or less, a decrease in adhesive strength due to excessive hardness of the adhesive layer (Y1) can be suppressed. A more preferred lower limit of the content of the tackifier resin (T1) is 10 parts by mass, and a more preferred upper limit is 20 parts by mass.

[0102] 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 layer (Y1) can have a higher adhesive strength. In particular, the tackifier resin (T2) preferably contains at least one tackifier resin selected from the group consisting of rosin ester resins and terpene resins, as this can further increase the adhesive strength. Furthermore, the tackifier resin (T2) preferably contains a rosin ester resin, as this can further increase the adhesive strength even to adherends with low polarity (e.g., fluororesins).

[0103] 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 adhesive layer (Y1) from becoming too soft and losing 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 adhesive layer (Y1), thereby preventing interfacial peeling. Furthermore, 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 adhesive layer (Y1) described below is appropriately reduced, and the flexibility of the adhesive layer (Y1) is further improved, thereby further improving the adhesive strength of the adhesive layer (Y1) to the fluororesin. The softening temperature of the tackifier resin (T2) is more preferably 70°C and more preferably 150°C. The softening temperature is measured in accordance with JIS K2207 (ring and ball method).

[0104] The tackifier resin (T2) preferably has a hydroxyl value of 0 mgKOH / g (lower limit) and 200 mgKOH / g (upper limit). The hydroxyl value of the tackifier resin (T2) within the above range improves the wettability of the interface of the adhesive layer (Y1), thereby preventing interfacial peeling. The hydroxyl value of the tackifier resin (T2) is more preferably 30 mgKOH / g (lower limit) and 130 mgKOH / g (upper limit). The hydroxyl value can be measured according to JIS K1557 (phthalic anhydride method).

[0105] The rosin ester resin is a resin obtained by esterifying, with an alcohol, a rosin resin primarily composed of abietic acid, a disproportionated rosin resin, a hydrogenated rosin resin, a dimer (polymerized rosin resin) of a resin acid such as abietic acid, or the like. The hydroxyl value is adjusted to the above-mentioned range by retaining some of the hydroxyl groups of the alcohol used in the esterification without being used in the esterification and remaining in the resin. Examples of the alcohol include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol. Examples of the rosin ester resin include Pine Crystal KE-359 (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value: 40 mgKOH / g, softening temperature: 100°C).

[0106] The terpene resin is a resin having structural units derived from monoterpene compounds and not having structural units derived from aromatic compounds. Examples of the terpene resin include YS Resin PX1250 (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value: 0 mg KOH / g, softening temperature: 125°C).

[0107] The terpene phenolic resin is a resin having structural units derived from a monoterpene compound and structural units derived from a phenolic compound. In this specification, the term "phenolic compound" in the terpene phenolic resin refers to a compound containing an aromatic ring structure having only one phenolic hydroxyl group, but not containing an aromatic ring structure having two or more phenolic hydroxyl groups. The structural units derived from the phenolic compound in the terpene phenolic resin do not include the structural units (A-1) and (A-1'). Examples of the terpene phenolic resin include YS Polystar G150 (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value: 120 mg KOH / g, softening temperature: 150°C).

[0108] Examples of the petroleum-based resin include Alcon P-140 (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value: 0 mgKOH / g, softening temperature: 140° C.).

[0109] The content of the tackifier resin (T2) relative to 100 parts by mass of the base polymer (P1) is preferably 10 parts by mass or more at a lower limit and 100 parts by mass or more at a higher limit. 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 100 parts by mass or less, the adhesive layer (Y1) can be prevented from becoming too hard and losing its adhesive strength. 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 60 parts by mass, and even more preferably 50 parts by mass, and even more preferably 40 parts by mass.

[0110] When the base polymer (P1) contains a (meth)acrylic copolymer, the adhesive layer (Y1) preferably further contains a curing agent. By containing the curing agent in the adhesive layer (Y1), the (meth)acrylic copolymer can form a structure crosslinked by chemical crosslinking, thereby further improving the bulk cohesive strength of the adhesive layer (Y1) and increasing the gel fraction of the adhesive layer (Y1), which will be described later, thereby further improving the adhesive strength of the resulting adhesive sheet.

[0111] Examples of the curing agent include an isocyanate-based curing agent, an aziridine-based curing agent, an epoxy-based curing agent, a metal chelate-based curing agent, etc. Among these, it is preferable that the curing agent 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).

[0112] Examples of the isocyanate curing agent include Coronate L-45 (manufactured by Tosoh Corporation), Takenate 500 (manufactured by Mitsui Chemicals, Inc.), and Desmodur L-75 (manufactured by Covestro).

[0113] 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 20 parts by mass at the upper limit. By having the content of the curing agent within this 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, more preferably 10.0 parts by mass at the upper limit, even more preferably 0.5 parts by mass at the lower limit, and even more preferably 8.0 parts by mass at the upper limit.

[0114] When the base polymer (P1) contains a silicone resin, the adhesive layer (Y1) preferably further contains a catalyst. By containing a catalyst in the adhesive layer (Y1), 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 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).

[0115] Examples of the catalyst include platinum catalysts, benzoyl peroxide, etc. Among these, it is preferable that the catalyst contains a platinum catalyst, from the viewpoints of suppressing odor and improving the tear strength and compression set of the adhesive layer (Y1).

[0116] An example of the platinum catalyst is CAT-PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0117] The content of the catalyst relative to 100 parts by mass of the silicone resin is preferably 0.01 parts by mass at the lower limit, and preferably 5.0 parts by mass at the upper limit.By the content of the catalyst being within the above range, the silicone resin can be crosslinked appropriately, and the adhesive strength of the adhesive layer (Y1) is further improved.The content of the catalyst is more preferably 0.1 parts by mass at the lower limit, more preferably 3.0 parts by mass at the upper limit, even more preferably 0.2 parts by mass at the lower limit, and even more preferably 2.0 parts by mass at the upper limit.

[0118] The adhesive layer (Y1) may further contain a coloring material for the purpose of imparting light-shielding properties. Examples of the coloring material include carbon black, aniline black, titanium oxide, etc. Among these, carbon black is preferred because it is relatively inexpensive and chemically stable.

[0119] The 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.

[0120] The loss tangent (tan δ) of the adhesive layer (Y1) measured at a frequency of 10 Hz in dynamic viscoelasticity measurement (hereinafter sometimes referred to as "the loss tangent of the adhesive layer (Y1) measured at a frequency of 10 Hz") preferably has a peak in the temperature range of -30°C or higher and 15°C or lower. When the loss tangent (tan δ) of the adhesive layer (Y1) measured at a frequency of 10 Hz has a peak in the temperature range of -30°C or higher, the adhesive strength of the adhesive layer (Y1) to the fluororesin is further improved. Furthermore, when the loss tangent (tan δ) of the adhesive layer (Y1) measured at a frequency of 10 Hz has a peak in the temperature range of 15°C or lower, the zipping phenomenon that occurs when peeling off the film protecting the adhesive layer of the adhesive sheet can be suppressed, and the resulting adhesive sheet can be used without losing its adhesive strength. The peak temperature at which the loss tangent of the adhesive layer (Y1) measured at a frequency of 10 Hz reaches a peak (hereinafter, may be simply referred to as the "peak temperature of the loss tangent") is more preferably −25°C, more preferably 13°C, still more preferably −20°C, and still more preferably 11°C.

[0121] 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, and 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 obtained will have superior adhesive strength. In addition, the flexibility of the adhesive layer (Y1) will be excellent, and the adhesive strength of the adhesive layer (Y1) to fluororesins will be further improved. A more preferred 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.

[0122] The peak temperature of the loss tangent of the adhesive layer (Y1) measured at a frequency of 10 Hz and the shear storage modulus of the adhesive layer (Y1) at 25°C can be measured by dynamic viscoelasticity measurement. Specifically, an adhesive layer is laminated to a thickness of 1 mm to prepare a measurement sample consisting of only the adhesive layer, and the shear storage modulus of the 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 (manufactured by IT Measurement & Control Co., Ltd., "DVA-200", etc.) 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 adhesive layer (Y1) can be obtained from the dynamic viscoelasticity spectrum obtained at this time.

[0123] The peak temperature of the loss tangent (tan δ) of the adhesive layer (Y1) measured at a frequency of 10 Hz and the shear storage modulus at 25°C of the adhesive layer (Y1) can be adjusted by the types and content ratios of the 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 adhesive layer (Y1) described below, and the like.

[0124] The gel fraction of the adhesive layer (Y1) preferably has a lower limit of 0% by mass and an upper limit of 99% by mass. When the gel fraction of the adhesive layer (Y1) is 0% by mass or more, the bulk strength of the adhesive layer (Y1) is increased, and the resulting adhesive sheet has superior adhesive strength. When the gel fraction of the adhesive layer (Y1) is 99% by mass or less, the shear storage modulus at 25°C of the adhesive layer (Y1) is appropriately reduced, the flexibility of the adhesive layer (Y1) is further improved, and the adhesive strength of the adhesive layer (Y1) to fluororesins is further improved. The adhesion to the substrate is further improved. The gel fraction of the adhesive layer (Y1) is more preferably 10% by mass, more preferably 60% by mass, even more preferably 25% by mass, and even more preferably 50% by mass. The gel fraction of the adhesive layer (Y1) can be measured by the following method, etc. The adhesive sheet is cut into a flat rectangular shape of 50 mm wide x 100 mm long to prepare a test piece. 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 (2). Note that no release film for protecting the adhesive layer (Y1) is laminated on the test piece. If the adhesive sheet does not have a substrate, W ０ = 0. Gel fraction (mass%) = 100 × (W ２ -W ０ ) / (W １ -W０ ) (2) (W ０ : Mass of the substrate, W １ : mass of test piece before immersion, W ２ : Mass of test piece after immersion and drying)

[0125] The gel fraction of the adhesive layer (Y1) can be adjusted to fall within the above range by, for example, 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.

[0126] The thickness of the adhesive layer (Y1) is preferably 25 μm at its lower limit and 1000 μm at its upper limit. If 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 50 μm at its lower limit and 500 μm at its upper limit, still more preferably 100 μm at its lower limit and 300 μm at its upper limit.

[0127] The adhesive sheet of the present invention may have layers other than the substrate and the adhesive layer (Y1) as needed.

[0128] The adhesive sheet of the present invention preferably further comprises an adhesive layer (Y2) on the other surface of the substrate, which enables the fluororesin and a different material to be bonded together at the same time.

[0129] The adhesive layer (Y2) has no front or back and is preferably the same as the adhesive layer (Y1) described above, from the viewpoint of improving handleability.

[0130] When the adhesive layer (Y2) is different from the adhesive layer (Y1), the adhesive layer (Y2) is preferably a low-tack adhesive layer from the viewpoint of ease of lamination. When the adhesive layer (Y2) is a low-tack adhesive layer, the stickiness of the adhesive layer (Y2) can be suppressed, and the adhesive sheet obtained has better ease of lamination.

[0131] The probe tack value of the adhesive layer (Y2) measured under conditions of 23°C, a pressure of 98 gf, a pressure rate of 100 mm / sec, a pressure 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 preferably 2000 gf / 5 mmφ. By having the probe tack value of the adhesive layer (Y2) at 23°C of 2000 gf / 5 mmφ or less, the stickiness of the adhesive layer (Y2) can be suppressed, resulting in the adhesive sheet of the present invention having superior lamination workability. The upper limit of the probe tack value of the adhesive layer (Y2) at 23°C is more preferably 1500 gf / 5 mmφ, and even more preferably 1000 gf / 5 mmφ. The lower limit of the probe tack value of the adhesive layer (Y2) at 23°C is preferably 1.0 gf / 5 mmφ. When the probe tack value of the adhesive layer (Y2) at 23°C is 1.0 gf / 5 mmφ or more, the adhesive layer (Y2) has appropriate adhesive strength, and from the viewpoint of making it easier to adjust the attachment position of the adhesive sheet of the present invention, the lamination workability is improved. A more preferred lower limit of the probe tack value of the adhesive layer (Y2) at 23°C is 10 gf / 5 mmφ, and an even more preferred lower limit of the probe tack value of the adhesive layer (Y2) at 23°C is 100 gf / 5 mmφ. The probe tack value of the adhesive layer (Y2) at 23°C can be measured by a probe tack test in accordance with JIS Z3284. Specifically, for example, the adhesive sheet of the present invention can be cut into a size of 30 mm wide x 30 mm long to prepare a test piece, and the adhesive layer (Y2) of the prepared test piece can be subjected to a probe tack test using a probe tack tester (such as "TAC-2" manufactured by RHESCA) under conditions of 23°C, a pressure of 98 gf, a pressure rate of 100 mm / sec, a pressure time of 10 seconds, and a peel rate of 5 mm / sec to measure.

[0132] Methods for adjusting the probe tack value of the adhesive layer (Y2) at 23°C include changing the composition or content ratio of the base polymer (P2) or tackifier resin (T3) contained in the adhesive layer (Y2), or changing the thickness of the adhesive layer (Y2).

[0133] The adhesive layer (Y2) has a 180° peel strength from SUS at 23°C when pressure-bonded at 0.1 MPa for 10 minutes in a 150°C environment (hereinafter sometimes simply referred to as "the 180° peel strength from SUS at 23°C of the adhesive layer (Y2) after heating") of preferably 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, it can exhibit excellent adhesive strength upon heating, and 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 more preferably 20 N / 25 mm. Furthermore, there is no particular upper limit to the 180° peel strength of the adhesive layer (Y2) from SUS at 23°C after heating, but from the viewpoint of adhesion of the PTFE sheet, a preferred upper limit is 500 N / 25 mm, a more preferred upper limit is 400 N / 25 mm, and an even more preferred upper limit is 300 N / 25 mm. The 180° peel strength of the adhesive layer (Y2) from SUS at 23°C after heating can be measured by the following method, etc. That is, the adhesive sheet is cut to a size of 25 mm wide x 100 mm long, and the adhesive layer (Y1) is lined with a 2 mm thick polytetrafluoroethylene sheet (manufactured by Yodogawa Hutech Co., Ltd., "Iodoflon"), and then the adhesive layer is pressure-bonded to a SUS plate (a SUS304 plate washed with ethanol and then wiped dry) by applying pressure at 0.1 MPa for 10 minutes in an environment of 150°C, and then air-cooled to prepare a test sample. The obtained test sample is subjected to a 180° peel test 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 from the SUS plate, whereby the 180° peel strength of the adhesive layer (Y2) against SUS at 23°C can be measured.

[0134] Examples of methods for adjusting the 180° peel strength of the adhesive layer (Y2) from SUS at 23°C after heating include methods of changing the composition of the base polymer (P2) contained in the adhesive layer (Y2) or the thickness of the adhesive layer (Y2).

[0135] The 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 viewpoint of easily adjusting the probe tack value and improving heat resistance, it is preferable to contain 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.

[0136] 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 SK1986DT (both manufactured by Soken Chemical & Engineering Co., Ltd.).

[0137] 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 PPET1200F (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.).

[0138] From the viewpoint of further improving 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 (T1) and tackifier resin (T2) described above.

[0139] When the base polymer (P2) contains the (meth)acrylic copolymer, the adhesive layer (Y2) preferably further contains a curing agent, which allows the (meth)acrylic copolymer to form a chemically crosslinked structure, thereby further improving the adhesive strength of the resulting adhesive sheet.

[0140] As the curing agent contained in the adhesive layer (Y2), for example, the same curing agent as that contained in the adhesive layer (Y1) can be used.

[0141] The adhesive layer (Y2) may contain conventionally known fine particles and additives, such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers, as required.

[0142] The thickness of the adhesive layer (Y2) is preferably 20 μm at its lower limit and 1000 μm at its upper limit. By setting the thickness of the adhesive layer (Y2) 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, more preferably 500 μm at its upper limit, and even more preferably 300 μm at its upper limit.

[0143] The method for producing the adhesive sheet of the present invention is not particularly limited, and examples thereof include the following methods. 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 then 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 having an adhesive layer (Y1). The laminate film thus produced is then superimposed on a substrate so that the adhesive layer (Y1) faces the substrate, and the laminate is then cured for 48 hours in an environment of 40°C and 50% RH, thereby obtaining an adhesive sheet having a substrate and an adhesive layer (Y1) on one side of the substrate. The step of applying the adhesive solution (a) to the release-treated surface of the release PET film may be completed in one go, or may be performed multiple times by applying the adhesive solution (a) in an overlapping manner to the applied adhesive solution. By adjusting the number of application steps, the thickness of the adhesive layer (Y1) can be easily adjusted. In addition, another laminate film is produced by applying an adhesive solution (b) prepared by a similar method to the release-treated surface of a release PET film, and completely drying and removing the solvent in the solution to form an adhesive layer (Y2). The step of applying the adhesive solution (b) to the release-treated surface of the release PET film may be performed once, or multiple times by applying the solution in layers on top of the applied adhesive solution. By adjusting the number of application steps, the thickness of the adhesive layer (Y2) can be easily adjusted. The prepared other laminate film is superimposed on a substrate so that the adhesive layer (Y2) faces the side of the substrate that does not have the adhesive layer (Y1), and the film is cured for 48 hours in an environment of 40°C and 50% RH, thereby obtaining an adhesive sheet having a substrate, an adhesive layer (Y1) on one side of the substrate, and an adhesive layer (Y2) on the other side of the substrate.

[0144] The adhesive sheet of the present invention is not particularly limited in its applications, but because it exhibits excellent adhesion to fluororesins such as polytetrafluoroethylene without pretreatment, it is suitable for bonding fluororesins to dissimilar materials for a variety of purposes. More specifically, the various purposes include promoting slip 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 can inhibit substrate peeling and provide high-strength adhesion, it is particularly suitable for use in bonding lining sheets to can bodies in chemical tanks for semiconductors or chemical industries. A chemical tank having the adhesive sheet of the present invention attached to the inner surface of the can body also constitutes one aspect of the present invention. A chemical tank having the adhesive sheet of the present invention attached to the inner surface of a can body is capable of firmly bonding the fluororesin to the inner surface of the can body via the adhesive layer (Y1) of the attached adhesive sheet of the present invention, and therefore peeling or floating of the fluororesin due to chemical solutions stored in a chemical tank to which the fluororesin is attached can be further suppressed.

[0145] The present invention also relates to a laminate sheet having a fluororesin-containing sheet on a surface of the adhesive layer (Y1) other than the surface that contacts the substrate. Because the laminate sheet of the present invention has a fluororesin-containing sheet, the use of the laminate sheet of the present invention makes it easier to bond fluororesins for various purposes.

[0146] In the laminated sheet of the present invention, the sheet containing the above-mentioned fluororesin can be exemplified by the sheet containing polytetrafluoroethylene (PTFE), the sheet containing perfluoroalkoxyalkane (PFA), the sheet containing perfluoroethylenepropene copolymer (FEP), the sheet containing ethylenetetrafluoroethylene copolymer (ETFE), the sheet containing polyvinylidene fluoride (PVDF), the sheet containing polyvinyl fluoride (PVF), the sheet containing polychlorotrifluoroethylene (PCTFE), the sheet containing ethylenechlorotrifluoroethylene copolymer (ECTFE), etc. Among them, the sheet containing PTFE is preferred because it has excellent heat resistance and chemical resistance.

[0147] The laminate sheet of the present invention is not particularly limited in its applications, but it can be suitably used to bond fluororesins to dissimilar components for various 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. The adherends to be protected from chemical solutions are not particularly limited, but examples include can bodies, trays, and walls. Specifically, it can be suitably used as a coating material for semiconductor chemical tanks, chemical tanks for the chemical industry, and pipes for transporting chemical solutions, a coating material for electronic components, and building materials. In particular, the laminate sheet of the present invention is more suitably used for lining the can body (surface treatment covering the inner surface of the can body) of a chemical tank for semiconductors or a chemical tank for the chemical industry. A chemical tank having the laminate sheet of the present invention attached to the inner surface of the can body also constitutes the present invention. The present invention also provides a method for producing a chemical tank for semiconductors or a chemical tank for the chemical industry, which method includes a step of attaching the laminated sheet of the present invention to the inner surface of a can body of the chemical tank.

[0148] The present invention also includes a method for producing a chemical liquid tank for semiconductors or a chemical liquid tank for the chemical industry, the method comprising: a laminated sheet production step of using an adhesive sheet of the present invention having an adhesive layer (Y2) on the other surface of a substrate, and pressing a sheet containing a fluororesin to the adhesive layer (Y1); and a step of attaching the adhesive layer (Y2) of the laminated sheet to the inner surface of a can body of the chemical liquid tank.

[0149] In the process of preparing the laminated sheet, the sheet containing the fluororesin can be exemplified as the sheet containing polytetrafluoroethylene (PTFE), the sheet containing perfluoroalkoxyalkane (PFA), the sheet containing perfluoroethylenepropene copolymer (FEP), the sheet containing ethylenetetrafluoroethylene copolymer (ETFE), the sheet containing polyvinylidene fluoride (PVDF), the sheet containing polyvinyl fluoride (PVF), the sheet containing polychlorotrifluoroethylene (PCTFE), the sheet containing ethylenechlorotrifluoroethylene copolymer (ECTFE) etc.Among them, the sheet containing PTFE is preferred because it has excellent heat resistance and chemical resistance.

[0150] According to the present invention, it is possible to provide an adhesive sheet that has excellent adhesion to fluororesins such as polytetrafluoroethylene on one side without pretreatment of the fluororesins, and that can suppress peeling of the substrate on the other side. The present invention also provides a laminate sheet having the adhesive sheet. Furthermore, the present invention also allows the manufacture of a chemical liquid tank to which the adhesive sheet or the laminate sheet is attached. Furthermore, the present invention also provides a method for manufacturing a chemical liquid tank using the laminate sheet or the adhesive sheet.

[0151] The following examples will explain the present invention in more detail, but the present invention is not limited to these examples.

[0152] (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 dropwise addition was completed, 0.1 parts by mass of azobisisobutyronitrile was added, and the polymerization reaction was allowed to proceed for an additional 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.

[0153] (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.

[0154] 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.

[0155]

[0156] (Preparation of Tackifier Resin (T1) and Tackifier Resin (T3)) (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 filtrate was subjected to a liquid separation operation. The toluene was then evaporated to obtain solid tackifier resins (T1) and (T3). Regarding the obtained tackifier resins (T1) and (T3), 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) and tackifier resin (T3) 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 weights of the tackifier resins (T1) and (T3) were measured, and the weight average molecular weight (Mw) was determined. The column used was a GPC KF-802.5L (manufactured by Showa Denko KK), and the detector was a differential refractometer. The results are shown in Table 2.

[0157] (Measurement of Biologically Derived Carbon Content in Tackifier Resin (T1) and Tackifier Resin (T3)) The biologically derived carbon contents of the obtained tackifier resins (T1) and (T3) were measured in accordance with ASTM D6866-22. The results are shown in Table 2.

[0158] (Synthesis Examples B to C and E) Tackifier resins (T1) and (T3) were synthesized and measured in the same manner as in Synthesis Example A above, except that in "(Preparation of tackifier resin (T1) and tackifier resin (T3))," the monomers were changed as shown in Table 2. The results are shown in Table 2.

[0159] Synthesis Example D Preparation of Tackifier Resin (T1) and Tackifier Resin (T3) 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 filtrate was subjected to a liquid separation operation. The toluene was then evaporated to obtain solid tackifier resins (T1) and (T3). Regarding the obtained tackifier resins (T1) and (T3), １ H-NMR measurement was performed to confirm that the tackifier resin (T1) and the tackifier resin (T3) were copolymers having a structural unit (A) derived from 4-vinylbenzoic acid and a structural unit (B) derived from α-pinene (copolymers having the structural unit (A) in the side chain). A solution of the obtained tackifier resin (T1) and the tackifier resin (T3) 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 weights of the tackifier resins (T1) and (T3) were measured, and the weight average molecular weight (Mw) was calculated. The column used was a GPC KF-802.5L (manufactured by Showa Denko KK), and the detector was a differential refractometer. The results are shown in Table 2.

[0160] (Measurement of Biologically Derived Carbon Content in Tackifier Resin (T1) and Tackifier Resin (T3)) The biologically derived carbon contents of the obtained tackifier resins (T1) and (T3) were measured in accordance with ASTM D6866-22. The results are shown in Table 2.

[0161]

[0162] Example 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) was added. Furthermore, 30 parts by mass of ethyl acetate (manufactured by Fuji Chemical Co., Ltd.) and 0.5 parts by mass of an isocyanate-based curing agent (manufactured by Covestro, "Desmodur L-75") were added and thoroughly stirred to obtain adhesive solution (a). The obtained adhesive solution (a) was applied to the release-treated surface of a 75 μm-thick release PET film (manufactured by Toyo Cross Co., Ltd., "SP3000") and dried at 100°C for 5 minutes to form a 50 μm-thick adhesive layer (Y1), thereby producing a laminated film. A 60 μm-thick nonwoven fabric (manufactured by Toray International Co., Ltd., "G2260-1S") was prepared as a substrate, and the prepared laminated film was superimposed on the substrate so that the adhesive layer (Y1) faced the substrate, followed by curing by heating at 40°C for 48 hours. This gave an adhesive sheet having a substrate and an adhesive layer (Y1) on one surface of the substrate.

[0163] (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 wide x 100 mm long, and then a 2 kg rubber roller was used to press the adhesive layer (Y1) surface onto a 2 mm thick polytetrafluoroethylene sheet (manufactured by Yodogawa Hutech Co., Ltd., "Yodoflon") by moving it back and forth once at a speed of 300 mm / min. A test sample was then prepared by leaving it to stand for 20 minutes in an environment of 23 ° C. and 50% RH and aging. A 180 ° peel test was performed on the obtained test sample in accordance with JIS Z0237 using a tensile tester (manufactured by ORIENTEC Co., Ltd., "Tensilon") under conditions of 23 ° C., 50% RH, and a peel speed of 300 mm / min. The adhesive layer (Y1) was peeled from the polytetrafluoroethylene film, and the 180 ° peel strength of the adhesive layer (Y1) against polytetrafluoroethylene at 23 ° C. was measured. The results are shown in Table 3.

[0164] (3) Measurement of Heat Shrinkage of Substrate The substrates shown in Table 3 were cut into 10 cm squares to prepare test pieces, which were then placed in an oven at 120°C and heated for 10 minutes. The heated test pieces were then air-cooled to room temperature, and the length of the test pieces was measured, and the heat shrinkage of the substrate was obtained using the following formula (1). In the following formula (1), the length of one side in "the length of one side of the test piece before heating" and "the length of one side of the test piece after heating" refers to the length of the same side. The results are shown in Table 3. Heat shrinkage (%) = ((the length of one side of the test piece before heating) - (the length of one side of the test piece after heating)) / (the length of the side of the test piece before heating) x 100 (1)

[0165] (Examples 2 to 14, Comparative Examples 1 to 7) Adhesive sheets were prepared and measurements were carried out in the same manner as in Example 1, except that in the above-mentioned "(1) Preparation of adhesive sheet", the composition and thickness of the adhesive layer (Y1) and the type and thickness of the substrate were changed as shown in Tables 3 and 5. The results are shown in Tables 3 and 5. The open-cell polyurethane foam "Poron" used in Example 14 was "Poron SR-S-70P".

[0166] (Examples 15-18, 21-23, Comparative Examples 8-9) (1) Preparation of Adhesive Sheets A laminated film having an adhesive layer (Y1) of the composition and thickness shown in Tables 4 and 6 was prepared in the same manner as in Example 1. Also, an adhesive solution (b) having the composition shown in Tables 4 and 6 was prepared in the same manner as in Example 1. The resulting adhesive solution (b) was applied to the release-treated surface of a 75 μm-thick release PET film (manufactured by Toyo Cross Co., Ltd., "SP3000") and dried at 100 ° C. for 5 minutes to produce a laminated film having an adhesive layer (Y2) of 50 μm in thickness. For the substrates shown in Tables 4 and 6, the adhesive layer (Y1) of one laminated film was superimposed on one side of the substrate, and the adhesive layer (Y2) of the other laminated film was superimposed on the other side of the substrate, and the laminated film was cured by heating at 40 ° C. for 48 hours. This resulted in an adhesive sheet having a substrate, an adhesive layer (Y1) on one side of the substrate, and an adhesive layer (Y2) on the other side of the substrate. In Examples 15 to 18 and Comparative Examples 8 to 9, the adhesive layers laminated on both sides of the substrate were similar, and adhesive layer (Y1) and adhesive layer (Y2) could not be distinguished. However, the adhesive layer (Y1) was the measurement target in the above-mentioned "(Measurement of 180° peel strength from polytetrafluoroethylene)" and the adhesive layer (Y2) was the measurement target for the 180° peel strength from SUS in the evaluation described below. Furthermore, the measurement target in "(4) Measurement of the probe tack value of adhesive layer (Y2) at 23°C" described below for Examples 15 to 18 was the adhesive layer (Y2).

[0167] (2) Measurement of 180° peel strength of adhesive layer (Y1) against polytetrafluoroethylene at 23° C. The adhesive layer (Y1) was pressure-bonded to a 2 mm thick polytetrafluoroethylene sheet (Yodogawa Hutech Co., Ltd., "Yodoflon"), and the 180° peel strength of adhesive layer (Y1) against polytetrafluoroethylene at 23° C. was measured in the same manner as in Example 1. The results are shown in Tables 4 and 6.

[0168] (3) Measurement of Heat Shrinkage of Substrate The heat shrinkage of the substrate was measured in the same manner as in Example 1. The results are shown in Tables 4 and 6.

[0169] (4) Measurement of Probe Tack Value of Adhesive Layer (Y2) at 23°C For Examples 15 to 18 and 21 to 23, the obtained adhesive sheets were cut to a size of 30 mm wide x 30 mm long to prepare test pieces. 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, pressure of 98 gf, pressure rate of 100 mm / sec, pressure time of 10 seconds, and peel rate of 5 mm / sec, and the probe tack value of the adhesive layer (Y2) at 23°C was measured. The results are shown in Tables 4 and 6.

[0170] (Examples 19 and 20) In the same manner as in Examples 15 to 18, 21 to 23, a laminate film having an adhesive layer (Y1) formed thereon with the composition and thickness shown in Table 4 was prepared, and then the laminate film was laminated on the substrate shown in Table 4 to obtain an adhesive sheet having a substrate and an adhesive layer (Y1) on one side of the substrate. Thereafter, in the same manner as in Examples 15 to 18, 21 to 23, a laminate film having an adhesive layer (Y2) formed thereon with the composition and thickness shown in Table 4 was prepared, and the adhesive layer (Y2) was thermally laminated at 100°C to the side of the adhesive sheet having a substrate and an adhesive layer (Y1) on one side of the substrate opposite the side having the adhesive layer (Y1), thereby obtaining an adhesive sheet having a substrate, an adhesive layer (Y1) on one side of the substrate, and an adhesive layer (Y2) on the other side of the substrate. Measurements were performed in the same manner as in Examples 15 to 18, 21 to 23, and Comparative Examples 8 to 9. The results are shown in Table 4.

[0171] <Evaluation> The adhesive sheets obtained in the examples and comparative examples were evaluated by the following methods. The results are shown in Tables 3 to 6.

[0172] (Adhesion strength of adhesive sheet to fluororesin) In the above-mentioned "(2) Measurement of 180° peel strength of adhesive layer (Y1) from polytetrafluoroethylene", the adhesive strength of the adhesive sheet to fluororesin was judged as follows: when the 180° peel strength of the obtained adhesive layer (Y1) from polytetrafluoroethylene at 23°C was 10 N / 25 mm or more, it was marked "◎", when it was 7 N / 25 mm or more and less than 10 N / 25 mm, it was marked "◯", when it was 5 N / 25 mm or more and less than 7 N / 25 mm, it was marked "△", and when it was less than 5 N / 25 mm, it was marked "X".

[0173] (Removability of Adhesive Sheet) The resulting adhesive sheet was cut into a size of 25 mm wide x 100 mm long to prepare a test piece. A chloroprene adhesive (manufactured by Cemedine Co., Ltd., "575F") was applied to a thickness of 100 μm using an applicator to the surface of a 1 mm thick SUS304 plate (a SUS304 plate that had been washed with ethanol and then wiped dry), and dried at 110°C for 30 minutes to form a chloroprene adhesive layer on the SUS304 plate. A 2 mm thick polytetrafluoroethylene sheet (manufactured by Yodogawa Hutech Co., Ltd., "Iodoflon") was then laminated onto the adhesive layer (Y1) surface of the prepared test piece, and the substrate or adhesive layer (Y2) of the laminated test piece (the substrate if the adhesive sheet was single-sided, or the adhesive layer (Y2) if the adhesive sheet was double-sided) was then superimposed on the formed chloroprene adhesive layer, and the test piece was then left to stand for 30 minutes under a load of 2 kg in an environment of 120°C, thereby preparing a test sample. The resulting test samples were subjected to a tensile test using a Tensilon tensile tester (manufactured by ORIENTEC Co., Ltd.) in accordance with JIS Z237, where the adhesive sheet was peeled from the SUS304 plate at 23°C, a peel rate of 300 mm / min, and a peel angle of 180°, to measure the 180° peel strength against SUS. The peelability of the adhesive sheet was judged as follows: if the resulting 180° peel strength against SUS was 40 N / 25 mm or more, it was marked "◎", if it was 20 N / 25 mm or more but less than 40 N / 25 mm, it was marked "◯", and if it was less than 20 N / 25 mm, it was marked "×". This evaluation evaluates the difficulty of peeling the adhesive sheet from the substrate.

[0174]

[0175]

[0176]

[0177]

[0178] According to the present invention, it is possible to provide an adhesive sheet that has excellent adhesion to fluororesins such as polytetrafluoroethylene on one side without pretreatment of the fluororesins, and that can suppress peeling of the substrate on the other side. The present invention also provides a laminate sheet having the adhesive sheet. Furthermore, the present invention also allows the manufacture of a chemical liquid tank to which the adhesive sheet or the laminate sheet is attached. Furthermore, the present invention also provides a method for manufacturing a chemical liquid tank using the laminate sheet or the adhesive sheet.

Claims

1. An adhesive sheet having a substrate and an adhesive layer (Y1) on one surface of the substrate, the substrate is made of at least one material selected from the group consisting of a nonwoven fabric, a glass cloth, a carbon cloth, a metal mesh, and a foam having an open-cell structure; The adhesive sheet has a 180° peel strength at 23°C on the adhesive layer (Y1) side from polytetrafluoroethylene of 5.0 N / 25 mm or more. An adhesive sheet characterized by:

2. 2. The adhesive sheet according to claim 1, further comprising an adhesive layer (Y2) on the other surface of the substrate.

3. the adhesive layer (Y1) contains a base polymer (P1) and a tackifying resin, 3. The adhesive sheet according to claim 1, wherein 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.

4. The adhesive sheet according to claim 3, wherein the tackifier resin comprises 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 formulas: 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 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.

5. The adhesive sheet according to claim 4 , 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-based monomers and vinyl-based monomers.

6. The adhesive sheet according to claim 3 , wherein 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.

7. 3. The adhesive sheet according to claim 1, wherein the adhesive layer (Y1) has a thickness of 25 μm or more and 1000 μm or less.

8. 3. The adhesive sheet according to claim 2, wherein the adhesive sheet has a probe tack value of 2000 gf / 5 mmφ or less on the adhesive layer (Y2) side, 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.

9. 9. The adhesive sheet according to claim 2 or 8, wherein the adhesive layer (Y2) has a thickness of 20 μm or more and 1000 μm or less.

10. 3. The adhesive sheet according to claim 1, which is used for lining the can body of a chemical tank for semiconductors or a chemical tank for the chemical industry.

11. 2. The adhesive sheet according to claim 1, further comprising a fluororesin-containing sheet on a surface of the adhesive layer (Y1) other than the surface that contacts the substrate.

12. The laminate sheet according to claim 11, which is used to protect an adherend.

13. 13. The laminated sheet according to claim 12, which is used to protect an adherend from chemical solutions.

14. A chemical tank having the adhesive sheet according to claim 1 or the laminated sheet according to claim 11 attached to the inner surface of a can body.

15. A method for manufacturing a chemical tank for semiconductors or a chemical tank for the chemical industry, comprising a step of attaching the laminated sheet according to claim 11, 12 or 13 to the inner surface of a can body of the chemical tank.

16. Using the adhesive sheet according to claim 2 or 8, a laminated sheet preparation step of pressure-bonding a sheet containing a fluororesin to the adhesive layer (Y1); a step of attaching the adhesive layer (Y2) of the laminated sheet to the inner surface of a can body of a chemical tank; A manufacturing method for chemical tanks for semiconductors or chemical industries, including:

Images