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

Abstract

The present invention provides an adhesive sheet that can suppress the lifting of the fluororesin from the can body during bonding and the tearing of the adhesive sheet after it has been folded, when the adhesive sheet is folded and bonded to the can body. The present invention also provides a laminated sheet having the adhesive sheet. Furthermore, it provides a chemical tank to which the adhesive sheet or the laminated sheet has been bonded. In addition, it provides a method for manufacturing a chemical tank using the adhesive sheet and the laminated sheet. [Solution] An adhesive sheet having a base material and an adhesive layer (Y1) formed on one side of the base material using an adhesive composition (X1), wherein the adhesive sheet has a 180° peel force of 50 N / 25 mm or more on SUS at 23°C on the side of the adhesive layer (Y1), and the adhesive sheet has a tensile yield strength of 100 N / cm or more.

Description

Technical Field

[0001] The present invention relates to an adhesive sheet. Further, the present invention relates to a laminated sheet having the adhesive sheet. Furthermore, the present invention relates to a chemical solution tank to which the adhesive sheet or the laminated sheet is attached. In addition, the present invention relates to a method for manufacturing a chemical solution tank using the adhesive sheet and the laminated sheet.

Background Art

[0002] Conventionally, when fixing various parts, adhesive sheets are widely used. Specifically, for example, an adhesive sheet is used to adhere a cover panel for protecting the surface of a portable electronic device to a touch panel module or a display panel module, or to adhere a touch panel module and a display panel module. For the adhesive sheet used for fixing such parts, in addition to high adhesiveness, functions such as heat resistance, heat conductivity, and impact resistance are required according to the environment of the site where it is used (for example, Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

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

[0005] In the semiconductor and chemical industries, many chemicals such as acids and alkalis are used, and lined tanks with fluororesin bonded to the tank body are widely used for corrosion prevention when storing or disposing of these chemicals. Conventionally, when bonding fluororesin to a tank body, adhesives such as chloroprene rubber or epoxy resin were applied to both the fluororesin and the tank body, and then heat-pressed to bond them. During bonding, the fluororesin is softened with a high-temperature flame, allowing it to conform to curved surfaces and achieve a tightly bonded lining. However, joining in this manner involves applying adhesive multiple times and allowing it to dry, which takes a long time to complete. Therefore, there is a demand for joining using adhesive sheets that can be used without pretreatment.

[0006] On the other hand, when bonding fluororesin to a can body using an adhesive sheet, methods such as using a laminated sheet in which fluororesin is laminated onto the adhesive layer of the adhesive sheet are employed to bond the fluororesin. However, when this method is used, problems arise such as the fluororesin lifting from the can body due to insufficient adhesive strength of the adhesive layer, and the adhesive sheet tearing when the fluororesin laminated onto the adhesive layer is stretched and bent because the base material of the adhesive sheet does not stretch completely.

[0007] The present invention provides an adhesive sheet that can suppress the lifting of the fluororesin from the can body during bonding and the tearing of the adhesive sheet after it has been folded, when the adhesive sheet is folded and bonded to the can body. The present invention also provides a laminated sheet having the adhesive sheet. Furthermore, the present invention provides a chemical tank to which the adhesive sheet or the laminated sheet has been bonded. In addition, the present invention provides a method for manufacturing a chemical tank using the adhesive sheet and the laminated sheet. [Means for solving the problem]

[0008] Disclosure 1 is an adhesive sheet having a substrate and an adhesive layer (Y1) formed on one side of the substrate using an adhesive composition (X1), wherein the adhesive sheet has a 180° peel force of 50 N / 25 mm or more at 23°C on the adhesive layer (Y1) side with respect to SUS, and the adhesive sheet has a tensile yield strength of 100 N / cm or more. Disclosure 2 is an adhesive sheet of Disclosure 1, wherein the substrate is made of a substrate having a mesh structure. Disclosure 3 is an adhesive sheet of Disclosure 2 in which the base material having the above mesh structure is a woven fabric base material. Disclosure 4 is an adhesive sheet of Disclosure 3, wherein the base material of the woven fabric is a base material woven in a twill weave or satin weave. Disclosure 5 is an adhesive sheet of Disclosure 1, 2, 3, or 4, in which the substrate having the above-mentioned mesh structure is composed of at least one selected from the group consisting of glass cloth, carbon cloth, alumina cloth, and metal mesh. Disclosure 6 is an adhesive sheet of Disclosure 1, 2, 3, 4, or 5, wherein the thickness of the substrate is 150 μm or more. Disclosure 7 is an adhesive sheet according to Disclosure 1, 2, 3, 4, 5, or 6, wherein the thickness of the adhesive layer (Y1) is 200 μm or more. Disclosure 8 is an adhesive sheet according to Disclosure 1, 2, 3, 4, 5, 6, or 7, wherein the 180° peel force to the PTFE on the adhesive layer (Y1) side is less than 5.0 N / 25 mm. Disclosure 9 is an adhesive sheet according to Disclosure 1, 2, 3, 4, 5, 6, 7, or 8, wherein the adhesive composition (X1) contains a base polymer (P1), and the base polymer (P1) comprises at least one selected from the group consisting of (meth)acrylic copolymers, styrene elastomers, and synthetic rubbers. Disclosure 10 is an adhesive sheet according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, or 9, wherein the adhesive composition (X1) contains a tackifying resin (T1). Disclosure 11 is an adhesive sheet of Disclosure 10 in which the tackifying resin (T1) comprises at least one tackifying resin selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins. Disclosure 12 is an adhesive sheet according to Disclosure 10 or 11, wherein the adhesive composition (X1) contains a base polymer (P1), and the content of the tackifying resin (T1) is 10 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the base polymer (P1). Disclosure 13 states that the adhesive composition (X1) is an adhesive sheet according to Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, which contains a silane coupling agent. Disclosure 14 is an adhesive sheet of Disclosure 13, comprising a silane coupling agent having at least one functional group selected from the group consisting of epoxy group, amino group, vinyl group, acrylic group, methacrylic group, isocyanate group, isocyanurate group, styryl group, ureido group, acid anhydride group, and mercapto group. Disclosure 15 is an adhesive sheet according to Disclosure 13 or 14, wherein the adhesive composition (X1) contains a base polymer (P1), and the content of the silane coupling agent is 0.1 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the base polymer (P1). Disclosure 16 further comprises an adhesive sheet of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15, having an adhesive layer (Y2) formed on the other surface of the substrate using an adhesive composition (X2). Disclosure 17 is an adhesive sheet according to Disclosure 16, wherein the thickness of the adhesive layer (Y2) is 200 μm or more. Disclosure 18 is an adhesive sheet according to Disclosure 16 or 17, wherein the 180° peel force to the PTFE on the adhesive layer (Y2) side is less than 5.0 N / 25 mm. Disclosure 19 is an adhesive sheet according to Disclosure 16, 17, or 18, wherein the adhesive composition (X2) contains a base polymer (P2), and the base polymer (P2) comprises at least one selected from the group consisting of (meth)acrylic copolymers, styrene elastomers, and synthetic rubbers. Disclosure 20 is an adhesive sheet of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19 used for lining a can in a chemical tank. Disclosure 21 is a laminated sheet having a sheet containing fluororesin on the adhesive layer (Y2) side of the adhesive sheet of Disclosure 16, 17, 18, or 19. Disclosure 22 is a laminated sheet of Disclosure 21 in which the sheet containing the fluororesin has at least one surface treatment layer selected from the group consisting of a sodium etching layer, a glass backing layer, and an atmospheric pressure plasma treatment layer on one of its surfaces. Disclosure 23 is a laminated sheet of Disclosure 21 or 22 used to protect an adherend. Disclosure 24 is a laminated sheet of Disclosure 23 used to protect an adherend from a chemical solution. Disclosure 25 is a chemical tank in which an adhesive sheet of Disclosure 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20, or a laminated sheet of Disclosure 21, 22, 23 or 24 is attached to the inner surface of a can body. Disclosure 26 is a method for manufacturing a chemical tank, which includes the step of attaching a laminated sheet of Disclosure 21, 22, 23, or 24 to the inner surface of the tank body of the chemical tank. Disclosure 27 is a method for manufacturing a chemical tank, comprising the steps of: manufacturing a laminated sheet using the adhesive sheet of Disclosure 16, 17, 18 or 19, and pressing a sheet containing fluororesin onto the adhesive layer (Y2); and attaching the adhesive layer (Y1) of the laminated sheet to the inner surface of the tank body of the chemical tank. The present invention will be described in detail below.

[0009] The inventors of the present invention studied an adhesive sheet having a base material and an adhesive layer (Y1) on one surface of the base material, setting the 180° peel strength against SUS at 23°C on the adhesive layer (Y1) side to be not less than a specific value and setting the tensile yield strength of the adhesive sheet to be not less than a specific value. As a result, it was found that an adhesive sheet capable of suppressing the occurrence of lifting of the fluororesin from the can body during pasting and the tearing of the adhesive sheet after bending the adhesive sheet can be obtained, leading to the completion of the present invention.

[0010] The adhesive sheet of the present invention is an adhesive sheet having a base material and an adhesive layer (Y1) formed by using an adhesive composition (X1) on one surface of the base material. In this specification, the above "adhesion" not only means a permanent adhesion phenomenon but also means having the meaning as "adhesion" which is a temporary adhesion phenomenon.

[0011] The adhesive sheet of the present invention has a base material. By having a base material, the present invention enables the production of a double-sided tape having two or more kinds of adhesive layers with different compositions and structures.

[0012] The above base material is preferably composed of a base material having a mesh structure. Since the base material having the above-described mesh structure has a passage for air and can suppress the generation of air, it has high air permeability, making it easy to remove the foaming that occurs during drying in the process of forming an adhesive layer with a large thickness. Therefore, when the above base material is composed of a base material having a mesh structure, even when the thickness of the adhesive layer is large, it is possible to suppress the remaining of foaming on the surface of the adhesive layer, and it becomes possible to more easily increase the thickness of the adhesive layer in order to improve the adhesive strength of the adhesive layer against SUS. In addition, since the above base material being composed of a base material having a mesh structure can suppress the generation of foaming on the surface of the adhesive layer, the adhesive sheet has a more excellent appearance.

[0013] The base material having the above mesh structure is preferably a fabric base material. Since the base material having the above mesh structure is a fabric base material, the flexibility of the base material is further improved, and when the adhesive sheet of the present invention bonds the fluororesin and the can body, the tearing of the adhesive sheet after bending the adhesive sheet can be further suppressed.

[0014] The fabric structure of the above fabric base material is not particularly limited, and examples include plain weave, twill weave, and damask weave. However, from the perspective that the flexibility of the above base material is further improved and the tearing of the adhesive sheet after bending the adhesive sheet when the adhesive sheet of the present invention bonds the fluororesin and the can body can be further suppressed, the above fabric base material is preferably a base material woven by twill weave or damask weave.

[0015] Examples of the base material having the above mesh structure include glass cloth, carbon cloth, alumina cloth, metal mesh, etc., and it is preferably composed of at least one selected from the group consisting of glass cloth, carbon cloth, alumina cloth, and metal mesh. Among them, from the perspective of being a fabric base material and further improving the flexibility of the above base material, it is more preferably composed of at least one selected from the group consisting of glass cloth, carbon cloth, and alumina cloth.

[0016] Examples of commercially available products of the above glass cloth include KS1132J (manufactured by Nitto Boseki Co., Ltd., plain weave), 1031NT-1270 S640 (manufactured by Arisawa Manufacturing Co., Ltd., plain weave), NGC-330-100 (manufactured by Nippon Glass Fiber Industry Co., Ltd., twill weave), KS120 (manufactured by Nitto Boseki Co., Ltd., damask weave), KS1080 (manufactured by Nitto Boseki Co., Ltd., plain weave), 1027NT-1270 S640 (manufactured by Arisawa Manufacturing Co., Ltd., plain weave), etc. Examples of commercially available products of the above carbon cloth include CF1K (manufactured by Arisawa Manufacturing Co., Ltd., plain weave), etc. Examples of commercially available products of the above alumina cloth include ALC (manufactured by Nippon Glass Fiber Industry Co., Ltd., plain weave), etc. Examples of commercially available metal meshes include Naslon (manufactured by Nippon Seisen Co., Ltd.).

[0017] The above-mentioned substrate may be composed of a substrate other than a substrate having a network structure. Examples of substrates other than those having the above-mentioned mesh structure include polyimide film and LCP film. Examples of commercially available polyimide films include Kapton 200H (manufactured by Toray DuPont) and UPILEX (manufactured by UBE).

[0018] The above-mentioned substrate preferably has a surface treatment layer. By having a surface treatment layer, the interlayer strength of the adhesive sheet of the present invention is further improved, and when bonding the fluororesin to the can body, the occurrence of the fluororesin lifting away from the can body during bonding can be further suppressed. Examples of the above-mentioned surface treatment layers include a corona treatment layer in which the surface of the substrate is corona treated, a heat cleaning layer in which the surface of the substrate is heat cleaned, a silane treatment layer in which the surface of the substrate is silane treated, and an atmospheric pressure plasma treatment layer in which the surface of the substrate is treated with atmospheric pressure plasma.

[0019] The thickness of the surface treatment layer described above can be adjusted to a suitable range depending on the thickness of the substrate, but specifically, the preferred lower limit for the thickness of the surface treatment layer is 1 nm. A thickness of 1 nm or more of the surface treatment layer further improves the interlayer strength of the adhesive sheet of the present invention, thereby further suppressing the occurrence of fluororesin lifting from the can body during bonding. A more preferred lower limit for the thickness of the surface treatment layer described above is 5 nm. Furthermore, the preferred upper limit for the thickness of the above surface treatment layer is 10 μm. By having a surface treatment layer thickness of 10 μm or less, the interlayer strength with the adhesive sheet is further improved without the surface treatment layer undergoing cohesive failure. A more preferred upper limit for the thickness of the above surface treatment layer is 5 μm.

[0020] The preferred lower limit for the thickness of the above-mentioned substrate is 150 μm. A thickness of 150 μm or more improves the strength of the substrate, thereby further suppressing tearing of the adhesive sheet after bending when bonding the fluororesin to the can body. A more preferred lower limit for the thickness of the above-mentioned substrate is 200 μm, and an even more preferred lower limit is 300 μm. Furthermore, from the viewpoint of further improving the flexibility of the substrate, the preferred upper limit for the thickness of the substrate is 1000 μm, and the more preferred upper limit is 500 μm.

[0021] The adhesive sheet of the present invention has an adhesive layer (Y1) formed using an adhesive composition (X1). The adhesive layer (Y1) is formed using the adhesive composition (X1). A method for forming the adhesive layer (Y1) using the adhesive composition (X1) is, for example, to apply the adhesive composition (X1) to a release film or the like, and then heat-dry the adhesive composition (X1).

[0022] The adhesive sheet of the present invention has a lower limit of 50 N / 25 mm for the 180° peel force against SUS at 23°C on the adhesive layer (Y1). Since the 180° peel force against SUS at 23°C on the adhesive layer (Y1) is 50 N / 25 mm or higher, the adhesive strength of the adhesive layer (Y1) to SUS is excellent. Therefore, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can suppress the occurrence of fluororesin lifting from the can body during bonding. A preferred lower limit for the 180° peel force against SUS at 23°C on the adhesive layer (Y1) is 70 N / 25 mm, and a more preferred lower limit is 100 N / 25 mm. Furthermore, there is no particular preferred upper limit for the 180° peel force against SUS at 23°C on the adhesive layer (Y1) side, but the practical upper limit is 500 N / 25 mm. The 180° peel force on the adhesive layer (Y1) at 23°C relative to SUS can be measured by the following method. Specifically, first, the obtained adhesive sheet is cut to a size of 25 mm wide x 100 mm long. Then, the adhesive layer (Y1) side is placed on a SUS plate (SUS304 plate that has been washed with ethanol and then wiped dry), and a 2 kg rubber roller is used to move it back and forth once at a speed of 300 mm / min. Finally, a laminate is created by pressing it under pressure at 0.1 MPa for 10 minutes in an environment of 120°C. Then, a 180° peel test is performed on the obtained laminate using a tensile testing machine (for example, "Tensilon" manufactured by ORIENTEC) in accordance with JIS Z 0237, under conditions of 23°C, 50% RH, and a peeling speed of 300 mm / min. By peeling the adhesive sheet from the SUS plate, the 180° peel force of the adhesive layer (Y1) side relative to SUS at 23°C can be measured. Furthermore, if the adhesive sheet of the present invention has an adhesive layer (Y2) described later, the adhesive sheet, with the adhesive layer (Y2) side backed with a 50 μm thick polyimide (PI) film, is cut by making one back-and-forth motion at a speed of 300 mm / min using a 2 kg rubber roller. After that, a laminate is prepared by the method described above, and a 180° peel test is performed.

[0023] Methods for adjusting the 180° peel force on SUS at 23°C on the adhesive layer (Y1) side include, for example, changing the type or constituent units of the base polymer (P1) described later (for example, changing the copolymerization ratio or monomer composition of the base polymer (P1)), adjusting the type or content of the tackifying resin (T1) described later, changing the thickness of the adhesive layer (Y1), or changing the substrate.

[0024] The adhesive layer (Y1) is formed using the adhesive composition (X1). The above adhesive composition (X1) preferably contains a base polymer (P1). Examples of the base polymer (P1) include (meth)acrylic copolymers, styrene elastomers, silicone resins, urethane resins, and synthetic rubbers. In particular, from the viewpoint of easily exhibiting strong adhesion and being able to easily adjust the monomer composition, the base polymer (P1) preferably contains at least one selected from the group consisting of (meth)acrylic copolymers, styrene elastomers, and synthetic rubbers, and more preferably contains at least one selected from the group consisting of (meth)acrylic copolymers and styrene elastomers. In this specification, the term "base polymer" refers to a polymer that accounts for 50% by mass or more of the polymers with a weight-average molecular weight of 50,000 or more contained in the adhesive composition. Furthermore, in this specification, "(meth)acrylic" means acrylic or methacrylic.

[0025] The above (meth)acrylic copolymer preferably has constituent units derived from alkyl (meth)acrylate. The above-mentioned alkyl (meth)acrylate-derived structural units preferably include structural units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester terminus. The above-mentioned (meth)acrylic copolymer has structural units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester terminus, thereby further lowering the glass transition temperature (Tg) of the above-mentioned (meth)acrylic copolymer. As a result, the flexibility of the above-mentioned adhesive layer (Y1) is further improved, so that when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of lifting of the fluororesin from the can body during bonding can be further suppressed. In addition, the tearing of the adhesive sheet after bending can be further suppressed. In this specification, "(meth)acrylate" means acrylate or methacrylate. Furthermore, in this specification, the above-mentioned "alkyl (meth)acrylate having an alkyl group at the ester terminus" means a (meth)acrylate in which an alkyl group is bonded to the oxygen atom of the ester bond.

[0026] Examples of alkyl (meth)acrylates having an alkyl group with 4 to 12 carbon atoms at the ester end 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, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 1-methylheptyl (meth)acrylate, and lauryl (meth)acrylate. In particular, when bonding the fluororesin and the can body, the adhesive sheet of the present invention preferably contains alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester end, in order to further suppress the occurrence of the fluororesin lifting away from the can body during bonding. The alkyl (meth)acrylates having an alkyl group with 4 to 12 carbon atoms at the ester terminus may be used alone or in combination of two or more types.

[0027] The preferred lower limit of the content of constituent units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester terminus in the above (meth)acrylic copolymer is 50% by mass. When the content of constituent units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester terminus is 50% by mass or more, the glass transition temperature (Tg) of the above (meth)acrylic copolymer is further reduced, and as a result the flexibility of the adhesive layer (Y1) is further improved. Therefore, when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of lifting of the fluororesin from the can body during bonding is further suppressed. In addition, the tearing of the adhesive sheet after bending is further suppressed. A more preferred lower limit for the content of structural units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester terminus is 90% by mass, and an even more preferred lower limit is 95% by mass. In particular, a preferred lower limit for the content of structural units derived from alkyl (meth)acrylate having an alkyl group with 6 to 8 carbon atoms at its ester terminus in the (meth)acrylic copolymer is 50% by mass, a more preferred lower limit is 85% by mass, and an even more preferred lower limit is 90% by mass. Furthermore, from the viewpoint of further improving the bulk cohesive force of the adhesive layer (Y1), the preferred upper limit for the content of constituent units derived from alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester terminus is 99.5% by mass, and the more preferred upper limit is 99% by mass.

[0028] The alkyl (meth)acrylate described above may include other alkyl (meth)acrylates other than the alkyl (meth)acrylate having an alkyl group with 4 to 12 carbon atoms at its ester terminus. 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, ester of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)octanol-1 with (meth)acrylic acid, ester of an alcohol with a total of 18 carbon atoms having 1 or 2 methyl groups in a linear main chain with (meth)acrylic acid, behenyl (meth)acrylate, arachidyl (meth)acrylate, and the like. The above-mentioned other alkyl (meth)acrylates may be used individually or in combination of two or more.

[0029] Preferably, the (meth)acrylic copolymer further has constituent units derived from a polar functional group-containing monomer. By having constituent units derived from a polar functional group-containing monomer in the (meth)acrylic copolymer, the bulk strength of the adhesive layer (Y1) is increased and the adhesive strength of the adhesive layer (Y1) to SUS is improved. Therefore, when the adhesive sheet of the present invention is bonded to the can body, the occurrence of the fluororesin lifting away from the can body during bonding can be suppressed.

[0030] The constituent units derived from the above polar functional group-containing monomers are constituent units derived from monomers containing functional groups that have reactivity such as crosslinking reactions, and it is preferable that the constituent units are derived from monomers containing at least one functional group selected from the group consisting of carboxyl groups, hydroxyl groups, amino groups, and epoxy groups. In particular, it is more preferable that the constituent units derived from the above polar functional group-containing monomers include one constituent unit selected from the group consisting of constituent units derived from carboxyl group-containing monomers and constituent units derived from hydroxyl group-containing monomers, as this can contribute to improving the adhesion strength of the adhesive layer (Y1) to SUS. Examples of constituent units derived from the above-mentioned carboxyl group-containing monomers include constituent units derived from (meth)acrylic acid. Examples of the hydroxyl group-containing monomers mentioned above include constituent units derived from 4-hydroxybutyl (meth)acrylate and constituent units derived from 2-hydroxyethyl (meth)acrylate. Examples of constituent units derived from polar functional group-containing monomers (epoxy group-containing monomers) having an epoxy group as the polar functional group include constituent units derived from glycidyl (meth)acrylate. The constituent units derived from the above polar functional group-containing monomers may be used individually or in combination of two or more types.

[0031] In the above (meth)acrylic copolymer, the preferred lower limit of the content of constituent units derived from the carboxyl group-containing monomer is 0.01% by mass, and the preferred upper limit is 6.0% by mass. By having the content of constituent units derived from the carboxyl group-containing monomer within this range, the bulk strength of the adhesive layer (Y1) is increased, and the adhesive strength of the adhesive layer (Y1) to SUS is further improved. Therefore, when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of fluororesin lifting from the can body during bonding is further suppressed. A more preferred lower limit of the content of constituent units derived from the carboxyl group-containing monomer is 0.05% by mass, and a more preferred upper limit is 3.0% by mass.

[0032] In the above (meth)acrylic copolymer, the preferred lower limit of the content of constituent units derived from the above hydroxyl group-containing monomer is 0.01% by mass, and the preferred upper limit is 5.0% by mass. When the content of constituent units derived from the above hydroxyl group-containing monomer is within this range, the bulk strength of the adhesive layer (Y1) is increased, and the adhesive strength of the adhesive layer (Y1) to SUS is further improved. Therefore, when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of fluororesin lifting from the can body during bonding is further suppressed. The more preferred lower limit of the content of constituent units derived from the above hydroxyl group-containing monomer is 0.05% by mass, and the more preferred upper limit is 3.0% by mass.

[0033] In the above (meth)acrylic copolymer, the preferred lower limit of the total content of constituent units derived from the above polar functional group-containing monomer is 0.01% by mass, and the preferred upper limit is 6.0% by mass. When the total content of constituent units derived from the above polar functional group-containing monomer is within this range, the bulk strength of the adhesive layer (Y1) is increased, and the adhesion strength of the adhesive layer (Y1) to SUS is improved, so that when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of fluororesin lifting from the can body during bonding is further suppressed. The more preferred lower limit of the total content of constituent units derived from the above polar functional group-containing monomer is 0.1% by mass, and the more preferred upper limit is 3.0% by mass.

[0034] The above (meth)acrylic copolymer may optionally contain structural units derived from other copolymerizable monomers other than the alkyl (meth)acrylate and the polar functional group-containing monomer. Examples of other monomers mentioned above include benzyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, and polypropylene glycol mono(meth)acrylate. In addition, other monomers that can be used include vinyl carboxylates such as vinyl acetate and various monomers commonly used in acrylic polymers such as styrene. The other monomers mentioned above may be used individually or in combination of two or more.

[0035] The preferred lower limit of the weight-average molecular weight (Mw) of the above (meth)acrylic copolymer is 50,000, and the preferred upper limit is 1,600,000. A weight-average molecular weight (Mw) of 50,000 or more increases the bulk strength of the adhesive layer (Y1) and improves the adhesion of the adhesive layer (Y1) to SUS. Therefore, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can more effectively suppress the lifting of the fluororesin from the can body during bonding. A weight-average molecular weight (Mw) of 1,600,000 or less further improves the flexibility of the adhesive layer (Y1). Therefore, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can more effectively suppress the lifting of the fluororesin from the can body during bonding. Furthermore, it becomes possible to more effectively suppress tearing of the adhesive sheet after bending. A more preferred lower limit of the weight-average molecular weight (Mw) of the above (meth)acrylic copolymer is 100,000, and a more preferred upper limit is 1,200,000.

[0036] The preferred lower limit of 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)) is 1.05, and the preferred upper limit is 10.0. A molecular weight distribution (Mw / Mn) of the (meth)acrylic copolymer of 1.05 or higher further improves the flexibility of the adhesive layer (Y1), thereby suppressing the lifting of the fluororesin from the can body during bonding. Furthermore, it helps to further suppress tearing of the adhesive sheet after bending. A molecular weight distribution (Mw / Mn) of the (meth)acrylic copolymer of 10.0 or lower reduces the proportion of low-molecular-weight components, increasing the bulk strength of the adhesive layer (Y1) and improving the adhesive strength of the adhesive layer (Y1) to SUS. Therefore, the adhesive sheet of the present invention further suppresses the lifting of the fluororesin from the can body during bonding. A more preferred upper limit for the molecular weight distribution (Mw / Mn) of the above (meth)acrylic copolymer is 9.0, a further preferred upper limit is 8.0, and a more preferred upper limit is 7.0.

[0037] In this specification, weight-average molecular weight (Mw) and number-average molecular weight (Mn) refer to the weight-average molecular weight and number-average molecular weight (Mn) measured in standard polystyrene equivalent as determined by gel permeation chromatography (GPC), respectively. Specifically, a (meth)acrylic copolymer is diluted 50-fold with tetrahydrofuran (THF), and the diluted solution is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The resulting filtrate is supplied to a gel permeation chromatograph (Waters, "2690 Separations Module," etc.), and GPC measurement is performed under conditions of sample flow rate of 1 mL / min and column temperature of 40°C to measure the polystyrene equivalent molecular weight of the (meth)acrylic copolymer and determine the weight-average molecular weight (Mw) and number-average molecular weight (Mn). For example, a GPC KF-802.5L (Showa Denko Corporation) can be used as the column, and for example, a differential refractometer can be used as the detector. Furthermore, the molecular weight distribution (Mw / Mn) can be measured using the obtained weight-average molecular weight (Mw) and number-average molecular weight (Mn).

[0038] Methods for adjusting the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the above-mentioned (meth)acrylic copolymer to within the above range include, for example, adjusting the composition of the monomers constituting the (meth)acrylic copolymer, the polymerization method, the polymerization conditions, etc.

[0039] The preferred lower limit of the glass transition temperature (Tg) of the above (meth)acrylic copolymer is -70°C, and the preferred upper limit is -30°C. Having the glass transition temperature of the above (meth)acrylic copolymer within this range results in the adhesive layer (Y1) having higher adhesion to SUS. A more preferred lower limit of the glass transition temperature (Tg) of the above (meth)acrylic copolymer is -60°C, and a more preferred upper limit is -40°C. In this specification, the glass transition temperature is the value obtained in the first run when measured using a differential scanning calorimeter (for example, Hitachi High-Tech Science Corporation's "SII Exstar 6000 / DSC 6220") under a nitrogen atmosphere and a heating rate of 10°C / min.

[0040] As polymerization methods for synthesizing the above-mentioned (meth)acrylic copolymer, conventionally known methods can be used in which monomers from which the above-mentioned constituent units are derived are subjected to a radical reaction in the presence of a polymerization initiator. Examples include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization. Among these, solution polymerization is preferred because it is easy to synthesize.

[0041] When solution polymerization is used as the polymerization method described above, examples of reaction solvents include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, and diethyl ether. The above reaction solvents may be used individually or in combination of two or more.

[0042] Examples of polymerization initiators include organic peroxides and azo compounds. Examples of the above-mentioned 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 above-mentioned azo compounds include azobisisobutyronitrile and azobiscyclohexanecarbonitride. The polymerization initiators described above may be used alone or in combination of two or more.

[0043] The styrene-based elastomer is preferably a block copolymer having a block derived from the styrene-based monomer and a block derived from a conjugated diene monomer, possessing rubber elasticity at room temperature, and having a hard segment portion and a soft segment portion. The block derived from the styrene-based monomer is the hard segment portion, and the block derived from the conjugated diene monomer is the soft segment portion.

[0044] Examples of the styrene monomers mentioned above 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 it is readily available industrially. Examples of the tertiary amino group-containing diphenylethylene mentioned above include 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene. The above-mentioned styrene monomers may be used individually or in combination of two or more types.

[0045] Examples of the above-mentioned conjugated diene monomers 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 due to their high polymerization reactivity and ease of industrial availability. The above-mentioned conjugated diene monomers may be used individually or in combination of two or more types.

[0046] Examples of the styrene-based elastomers mentioned above include styrene-isoprene-styrene (SIS) block copolymer, styrene-butadiene-styrene (SBS) block copolymer, styrene-ethylene-butylene-styrene copolymer (SEBS), and styrene-ethylene-propylene-styrene copolymer (SEPS). Among these, SIS block copolymer and SBS block copolymer are preferred, and SIS block copolymer is more preferred, because the resulting adhesive sheet tends to exhibit high adhesive strength and is less likely to peel off the adherend even when immersed in an alkaline chemical solution. The above-mentioned styrene-based elastomers may be used individually or in combination of two or more types.

[0047] The styrene-based elastomer preferably includes a triblock copolymer of a block derived from the styrene-based monomer and a block derived from the conjugated diene monomer, and more preferably includes a diblock copolymer of a block derived from the styrene-based monomer and a block derived from the conjugated diene monomer, in addition to the triblock copolymer. The preferred lower limit for the content of the diblock copolymer in the styrene-based elastomer (hereinafter sometimes referred to as the "diblock ratio") is 50% by mass. When the diblock ratio is 50% by mass or more, the flexibility of the adhesive layer (Y1) is further improved, and when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of lifting of the fluororesin from the can body during bonding is further suppressed. In addition, the tearing of the adhesive sheet after bending is further suppressed. The more preferred lower limit for the diblock ratio is 70% by mass. Furthermore, from the viewpoint of further improving the cohesive force of the adhesive layer (Y1), the preferred upper limit of the jiblock ratio is 90% by mass. The above diblock ratio can be calculated from the peak area ratio of each copolymer measured by gel permeation chromatography (GPC).

[0048] The preferred upper limit for the amount of blocks derived from the styrene monomer in the above-mentioned styrene-based elastomer (hereinafter sometimes referred to as "styrene content") is 20% by mass. By having a styrene content of 20% by mass or less, the flexibility of the adhesive layer (Y1) is further improved, and when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of lifting of the fluororesin from the can body during bonding can be further suppressed. In addition, the tearing of the adhesive sheet after bending can be further suppressed. A more preferred upper limit for the styrene content is 16% by mass. Furthermore, from the viewpoint of further improving the cohesive force of the adhesive layer (Y1), the preferred lower limit of the styrene content is 8% by mass. The above styrene content is, 1 It can be calculated from the peak area ratio of each block measured by 1H-NMR.

[0049] The preferred lower limit for the weight-average molecular weight of the above styrene-based elastomer is 50,000, and the preferred upper limit is 600,000. A weight-average molecular weight of 50,000 or more for the above styrene-based elastomer increases the bulk strength of the adhesive layer (Y1) and improves the adhesive strength of the adhesive layer (Y1) to SUS. Therefore, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can further suppress the occurrence of fluororesin lifting from the can body during bonding. A weight-average molecular weight of 600,000 or less for the above styrene-based elastomer further improves the compatibility between the styrene-based elastomer and other components. A more preferred lower limit for the weight-average molecular weight of the above styrene-based elastomer is 100,000, and a more preferred upper limit is 500,000.

[0050] Examples of the synthetic rubbers mentioned above include chloroprene rubber, nitrile rubber, acrylic rubber, isoprene rubber, ethylene propylene rubber, ethylene vinyl acetate rubber, urethane rubber, nitrile butadiene rubber, fluororubber, butadiene rubber, styrene butadiene rubber, and butyl rubber. In particular, from the viewpoint of heat resistance, chemical resistance, and weather resistance, it is preferable that the synthetic rubbers mentioned above include chloroprene rubber, which has chlorine in the carbon-carbon double bond in its molecule. Examples of commercially available chloroprene rubber include 575F (manufactured by Cemedyne Co., Ltd.) and G17 (manufactured by Konishi Co., Ltd.). Examples of commercially available nitrile rubbers include 501F (manufactured by Cemedyne Co., Ltd.).

[0051] The preferred lower limit of the content of the base polymer (P1) in the adhesive composition (X1) is 30% by mass, and the preferred upper limit is 99.5% by mass. By having the base polymer (P1) content within this range, the adhesive strength of the adhesive layer (Y1) to SUS is further improved, so that when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of fluororesin lifting from the can body during bonding can be further suppressed. A more preferred lower limit of the base polymer (P1) content is 40% by mass, a more preferred upper limit is 99% by mass, an even more preferred lower limit is 50% by mass, and an even more preferred upper limit is 95% by mass.

[0052] The adhesive composition (X1) preferably contains a tackifying resin (T1). By including the tackifying resin (T1) in the adhesive composition (X1), the adhesive strength of the adhesive layer (Y1) to SUS is further improved, so that when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of the fluororesin lifting away from the can body during bonding can be further suppressed.

[0053] The tackifying resin (T1) preferably contains at least one tackifying resin selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins. By including at least one tackifying resin selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins in the tackifying resin (T1), the adhesive strength of the adhesive layer (Y1) to SUS is further improved, so that when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of the fluororesin lifting away from the can body during bonding can be further suppressed. In particular, since the adhesive strength of the adhesive layer (Y1) to SUS can be further improved, it is more preferable that the tackifying resin (T1) contains at least one tackifying resin selected from the group consisting of rosin ester resins and terpene resins.

[0054] The preferred lower limit of the softening temperature of the tackifying resin (T1) is 50°C, and the preferred upper limit is 200°C. A softening temperature of 50°C or higher for the tackifying resin (T1) further improves the heat resistance of the adhesive layer (Y1). A softening temperature of 200°C or lower for the tackifying resin (T1) further improves the wettability and flexibility of the interface of the adhesive layer (Y1), and further improves the adhesive strength to SUS. Therefore, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can further suppress the lifting of the fluororesin from the can body during bonding. Furthermore, it becomes possible to further suppress tearing of the adhesive sheet after bending. A more preferred lower limit of the softening temperature of the tackifying resin (T1) is 70°C, and a more preferred upper limit is 150°C. The softening temperature refers to the softening temperature (softening point) measured according to JIS K 2207 (ring-ball method).

[0055] The preferred lower limit of the hydroxyl value of the tackifying resin (T1) is 0 mgKOH / g, and the preferred upper limit is 200 mgKOH / g. Having the hydroxyl value of the tackifying resin (T1) within this range further improves the wettability of the interface of the adhesive layer (Y1) and enhances the adhesive strength to SUS. Therefore, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can further suppress the occurrence of fluororesin lifting from the can body during bonding. A more preferred lower limit of the hydroxyl value of the tackifying resin (T1) is 30 mgKOH / g, and a more preferred upper limit is 130 mgKOH / g. The above hydroxyl value can be measured according to JIS K 1557 (phthalic anhydride method).

[0056] The rosin ester resins mentioned above are resins obtained by esterifying rosin resins mainly composed of abietic acid, disproportionated rosin resins, hydrogenated rosin resins, or dimers of resin acids such as abietic acid (polymerized rosin resins) with alcohol. Some of the hydroxyl groups of the alcohol used in esterification are not used in the esterification process and are instead contained within the resin, thereby adjusting the hydroxyl value to the range described above. Examples of such alcohols include polyhydric alcohols such as ethylene glycol, glycerin, and pentaerythritol. Examples of commercially available rosin ester resins include Pine Crystal KE-359 (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value: 40 mg KOH / g, softening temperature: 100°C).

[0057] The above-mentioned terpene resin is a resin that has structural units derived from monoterpene compounds and does not have structural units derived from aromatic compounds. Examples of commercially available terpene resins include YS Resin PX1250 (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value: 0 mg KOH / g, softening temperature: 125°C).

[0058] The above-mentioned terpene phenol resin is a resin having structural units derived from monoterpene compounds and structural units derived from phenol compounds. In this specification, the term "phenol compound" in the terpene phenol resin refers to a compound that contains an aromatic ring structure having only one phenolic hydroxyl group and does not contain an aromatic ring structure having two or more phenolic hydroxyl groups. Examples of commercially available terpene phenol resins include YS Polystar G150 (manufactured by Yasuhara Chemical Co., Ltd., hydroxyl value: 120 mg KOH / g, softening temperature: 150°C).

[0059] Examples of commercially available petroleum-based resins include Alcon P-140 (manufactured by Arakawa Chemical Industries, Ltd., hydroxyl value: 0 mg KOH / g, softening temperature: 140°C) and Quintone R100 (manufactured by Nippon Zeon Corporation, hydroxyl value: 0 mg KOH / g, softening temperature: 96°C).

[0060] The preferred upper limit for the content of the tackifying resin (T1) per 100 parts by mass of the base polymer (P1) is 150 parts by mass. By having a content of 150 parts by mass or less of the tackifying resin (T1), the flexibility of the adhesive layer (Y1) is further improved and the adhesive strength to SUS is further improved, so that when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, the occurrence of lifting of the fluororesin from the can body during bonding can be further suppressed. In addition, the tearing of the adhesive sheet after bending can be further suppressed. The more preferred upper limit for the content of the tackifying resin (T1) is 100 parts by mass, an even more preferred upper limit is 70 parts by mass, and an even more preferred upper limit is 40 parts by mass. The lower limit of the content of the tackifying resin (T1) is not particularly limited and may be 0 parts by mass (i.e., the adhesive layer (Y1) does not need to contain the tackifying resin (T1)). However, from the viewpoint of further improving the adhesive strength of the adhesive layer (Y1) to SUS, a preferred lower limit is 10 parts by mass, and a more preferred lower limit is 20 parts by mass.

[0061] The adhesive composition (X1) preferably contains a silane coupling agent. By containing a silane coupling agent in the adhesive composition (X1), the adhesive strength of the adhesive layer (Y1) to SUS is further improved, and when the adhesive sheet of the present invention is bonded to the can body, the occurrence of fluororesin lifting from the can body during bonding is further suppressed.

[0062] Examples of the silane coupling agents mentioned above include vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, and 3-aminopropyltriethoxysilane. In particular, from the viewpoint of further improving the adhesive strength of the adhesive layer (Y1) to SUS and further suppressing the occurrence of fluororesin lifting from the can body during bonding when the adhesive sheet of the present invention bonds the fluororesin to the can body, it is preferable that the silane coupling agent comprises a silane coupling agent having at least one functional group selected from the group consisting of epoxy group, amino group, vinyl group, acrylic group, methacrylic group, isocyanate group, isocyanurate group, styryl group, ureido group, acid anhydride group, and mercapto group, and more preferably comprises a silane coupling agent having at least one functional group selected from the group consisting of epoxy group and vinyl group. The silane coupling agents described above may be used individually or in combination of two or more.

[0063] The preferred lower limit for the content of the silane coupling agent per 100 parts by mass of the base polymer (P1) is 0.1 parts by mass, and the preferred upper limit is 5.0 parts by mass. A content of 0.1 parts by mass or more of the silane coupling agent further improves the adhesion of the adhesive layer (Y1) to SUS, and when the adhesive sheet of the present invention is bonded to the fluororesin and the can body, it further suppresses the occurrence of fluororesin lifting from the can body during bonding, and also improves adhesion to the substrate. A content of 5.0 parts by mass or less of the silane coupling agent can suppress bleed-out of the silane coupling agent. A more preferred lower limit for the content of the silane coupling agent is 0.5 parts by mass, a more preferred upper limit is 4.5 parts by mass, an even more preferred lower limit is 2.0 parts by mass, and an even more preferred lower limit is 3.0 parts by mass.

[0064] The adhesive composition (X1) preferably contains a crosslinking agent. In particular, if the base polymer (P1) contains the (meth)acrylic copolymer, the adhesive composition (X1) preferably contains a crosslinking agent. By containing a crosslinking agent in the adhesive composition (X1), the base polymer (P1) (such as the (meth)acrylic copolymer) can form a crosslinked structure by chemical crosslinking, thereby improving the bulk cohesive force of the adhesive layer (Y1). As a result, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can further suppress the occurrence of fluororesin lifting from the can body during bonding. Furthermore, from the viewpoint of storage stability, etc., the crosslinking agent may be added to the adhesive composition (X1) immediately before forming the adhesive layer (Y1).

[0065] Examples of the crosslinking agents include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-based crosslinking agents. In particular, it is preferable that the crosslinking agent includes at least one selected from the group consisting of isocyanate-based crosslinking agents and epoxy-based crosslinking agents, as this enables appropriate chemical crosslinking of the (meth)acrylic copolymer and further improves the adhesive strength of the adhesive layer (Y1).

[0066] Examples of commercially available isocyanate-based crosslinking agents include Takenate 500 (manufactured by Mitsui Chemicals, Inc.) and Desmodulo L-75 (manufactured by Covestro Corporation).

[0067] The preferred lower limit of the content of the crosslinking agent in the above adhesive composition (X1) per 100 parts by mass of the (meth)acrylic copolymer is 0.01 parts by mass, and the preferred upper limit is 20 parts by mass. By having the crosslinking agent content within this range, appropriate chemical crosslinking of the (meth)acrylic copolymer becomes possible, further improving the adhesive strength of the adhesive layer (Y1) to SUS. Therefore, when bonding the fluororesin to the can body, the adhesive sheet of the present invention can further suppress the occurrence of fluororesin lifting from the can body during bonding. A more preferred lower limit of the crosslinking agent content is 0.1 parts by mass, a more preferred upper limit is 10 parts by mass, an even more preferred lower limit is 0.5 parts by mass, and an even more preferred upper limit is 8.0 parts by mass.

[0068] The above adhesive composition (X1) may optionally contain conventionally known fine particles and additives such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers.

[0069] The adhesive layer (Y1) described above has a preferred lower limit of thickness of 200 μm. A thickness of 200 μm or more of the adhesive layer (Y1) further improves the adhesive strength of the adhesive layer (Y1) to SUS, thereby further suppressing the occurrence of fluororesin lifting from the can body during bonding when the adhesive sheet of the present invention is bonded to the can body. A more preferred lower limit for the thickness of the adhesive layer (Y1) is 250 μm, and an even more preferred lower limit is 300 μm. Furthermore, since the flexibility of the adhesive layer (Y1) is further improved, the adhesive sheet of the present invention can better suppress tearing of the adhesive sheet after bending when bonding the fluororesin to the can body. From this viewpoint, the preferred upper limit of the adhesive layer (Y1) is 1000 μm, and the more preferred upper limit is 500 μm.

[0070] It is preferable that the thickness of the adhesive layer (Y1) is 0.5 times or more the thickness of the substrate. By having an adhesive layer (Y1) thickness of 0.5 times or more the thickness of the substrate, adhesion to the substrate is improved and anchor strength can be improved. It is more preferable that the thickness of the adhesive layer (Y1) is 1 time or more the thickness of the substrate, and even more preferable that it is 2 times or more. Furthermore, it is preferable that the thickness of the adhesive layer (Y1) is 10 times or less the thickness of the base material. By having an adhesive layer (Y1) thickness of 10 times or less the thickness of the base material, it becomes less likely for wrinkles or other appearance defects to occur when the adhesive sheet of the present invention is rolled up. It is more preferable that the thickness of the adhesive layer (Y1) is 8 times or less the thickness of the base material, and even more preferable that it is 5 times or less.

[0071] The adhesive sheet of the present invention preferably has a 180° peel force of less than 5.0 N / 25 mm on the adhesive layer (Y1) side relative to PTFE. Having a 180° peel force of less than 5.0 N / 25 mm on the adhesive layer (Y1) side relative to PTFE suppresses contamination of the fluororesin by the adhesive layer (Y1) even if the adhesive layer (Y1) accidentally comes into contact with the fluororesin during the lining process when using the adhesive sheet of the present invention to line a can with fluororesin. Therefore, workability is further improved when using the adhesive sheet of the present invention to line a can with fluororesin. A more preferable upper limit for the 180° peel force of the adhesive layer (Y1) side relative to PTFE is 3.0 N / 25 mm, and an even more preferable upper limit is 1.0 N / 25 mm. Furthermore, there is no particular preferred lower limit for the 180° peel force on the PTFE side of the adhesive layer (Y1), but the practical lower limit is 0.01 N / 25 mm. The 180° peel force on the PTFE side of the adhesive layer (Y1) can be measured by the following method. Specifically, first, the adhesive sheet is cut to a size of 25 mm wide x 100 mm long. Then, the adhesive layer (Y1) side is placed on a 2 mm thick polytetrafluoroethylene board (for example, "Yodoflon" manufactured by Yodogawa Hutech Co., Ltd.), and after one back-and-forth motion using a 2 kg rubber roller at a speed of 300 mm / min, the laminate is pressed together by applying pressure at 0.1 MPa for 10 minutes in an environment of 120°C to create a laminate. Then, a 180° peel test is performed on the obtained laminate using a tensile testing machine (for example, "Tensilon" manufactured by ORIENTEC Co., Ltd.) in accordance with JIS Z 0237, under conditions of 23°C, 50% RH, and a peeling speed of 300 mm / min. By peeling the adhesive sheet from the polytetrafluoroethylene board, the 180° peel force of the adhesive layer (Y1) side relative to PTFE can be measured. Furthermore, if the adhesive sheet of the present invention has an adhesive layer (Y2) described later, the adhesive sheet is backed by passing a 50 μm thick polyimide (PI) film back and forth once with a 2 kg rubber roller at a speed of 300 mm / min against the adhesive layer (Y2) side. After cutting the backed adhesive sheet, a laminate is prepared and pressed together using the method described above, and a 180° peel test is performed. Furthermore, in this specification, "PTFE" as used in relation to "180° peel force against PTFE" refers to PTFE that has not undergone surface treatment.

[0072] Methods for adjusting the 180° peel force of the adhesive layer (Y1) to the PTFE within the range described above include, for example, changing the type or constituent units of the base polymer (P1) (for example, changing the copolymerization ratio or monomer composition of the base polymer (P1)), adjusting the type or content of the tackifying resin (T1), changing the thickness of the adhesive layer (Y1), or changing the substrate.

[0073] The adhesive sheet of the present invention may have layers other than the above-mentioned substrate and the above-mentioned adhesive layer (Y1), as long as the effects of the present invention are not impaired.

[0074] The adhesive sheet of the present invention preferably has an adhesive layer (Y2) formed from an adhesive composition (X2) on the other side of the substrate. The adhesive sheet of the present invention has an adhesive layer (Y2) on the other side of the substrate (the side without the adhesive layer (Y1)), which further improves the workability of the adhesive sheet of the present invention.

[0075] The above adhesive composition (X2) preferably contains a base polymer (P2). Examples of the base polymer (P2) include (meth)acrylic copolymers, styrene elastomers, silicone resins, urethane resins, and synthetic rubbers. In particular, from the viewpoint of easily exhibiting strong adhesion and being able to easily adjust the monomer composition, it is preferable that the base polymer (P2) contains at least one selected from the group consisting of (meth)acrylic copolymers, styrene elastomers, and synthetic rubbers.

[0076] Examples of the (meth)acrylic copolymer, styrene-based elastomer, and synthetic rubber in the above-mentioned base polymer (P2) are the same as those in the above-mentioned base polymer (P1).

[0077] The preferred lower limit for the content of the base polymer (P2) in the adhesive composition (X2) is 50% by mass, and the preferred upper limit is 99% by mass. Having the base polymer (P2) content within this range further improves the adhesive strength of the adhesive layer (Y2). A more preferred lower limit for the base polymer (P2) content is 75% by mass, and a more preferred upper limit is 90% by mass.

[0078] The adhesive composition (X2) preferably contains a tackifying resin (T2). The presence of a tackifying resin (T2) in the adhesive composition (X2) further improves the adhesive strength of the adhesive layer (Y2).

[0079] From the viewpoint of further improving the adhesive strength of the adhesive layer (Y2), it is preferable that the tackifying resin (T2) includes at least one tackifying resin selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins. Examples of the above-mentioned rosin ester resin, terpene resin, terpene phenol resin, and petroleum resin include those similar to those used in the tackifying resin (T1) described above.

[0080] The preferred lower limit for the content of the tackifying resin (T2) per 100 parts by mass of the base polymer (P2) is 10 parts by mass, and the preferred upper limit is 150 parts by mass. A content of 10 parts by mass or more of the tackifying resin (T2) further improves the adhesive strength of the adhesive layer (Y2). A content of 150 parts by mass or less of the tackifying resin (T2) further improves the flexibility of the adhesive layer (Y2) and further improves the adhesive strength of the adhesive layer (Y2). A more preferred lower limit for the content of the tackifying resin (T2) is 15 parts by mass, a more preferred upper limit is 100 parts by mass, an even more preferred lower limit is 20 parts by mass, an even more preferred upper limit is 70 parts by mass, and an even more preferred upper limit is 40 parts by mass.

[0081] The adhesive composition (X2) preferably contains a silane coupling agent. The presence of a silane coupling agent in the adhesive composition (X2) further improves the adhesive strength of the adhesive layer (Y2).

[0082] The silane coupling agent in the adhesive composition (X2) described above is the same as that in the adhesive composition (X1) described above. The silane coupling agents described above may be used individually or in combination of two or more.

[0083] The preferred lower limit for the content of the silane coupling agent per 100 parts by mass of the base polymer (P2) is 0.1 parts by mass, and the preferred upper limit is 5.0 parts by mass. A content of 0.1 parts by mass or more of the silane coupling agent further improves the adhesive strength of the adhesive layer (Y2). A content of 5.0 parts by mass or less of the silane coupling agent can suppress bleed-out of the silane coupling agent. A more preferred lower limit for the content of the silane coupling agent is 0.5 parts by mass, and a more preferred upper limit is 2.0 parts by mass.

[0084] The adhesive composition (X2) preferably contains a crosslinking agent. In particular, if the base polymer (P2) contains the (meth)acrylic copolymer, the adhesive composition (X2) preferably contains a crosslinking agent. By containing a crosslinking agent in the adhesive layer (Y2), the base polymer (P2) ((meth)acrylic copolymer, etc.) forms a crosslinked structure by chemical crosslinking, and the adhesive strength of the adhesive layer (Y2) is further improved. Furthermore, from the viewpoint of storage stability, etc., the crosslinking agent may be added to the adhesive composition (X2) immediately before forming the adhesive layer (Y2).

[0085] The crosslinking agent contained in the above adhesive composition (X2) preferably includes at least one selected from the group consisting of isocyanate-based crosslinking agents and epoxy-based crosslinking agents, from the viewpoint of enabling appropriate chemical crosslinking of the (meth)acrylic copolymer and further improving the adhesive strength of the above adhesive layer (Y2). In the adhesive composition (X2) described above, the isocyanate-based crosslinking agent and the epoxy-based crosslinking agent are the same as those in the adhesive composition (X1) described above.

[0086] The preferred lower limit for the content of the crosslinking agent in the adhesive composition (X2) per 100 parts by mass of the (meth)acrylic copolymer is 0.1 parts by mass, and the preferred upper limit is 10 parts by mass. Having the crosslinking agent content within this range allows for appropriate chemical crosslinking of the (meth)acrylic copolymer, further improving the adhesive strength of the adhesive layer (Y2). A more preferred lower limit for the crosslinking agent content is 0.5 parts by mass, and a more preferred upper limit is 5.0 parts by mass.

[0087] The above adhesive composition (X2) may optionally contain conventionally known fine particles and additives such as inorganic fine particles, conductive fine particles, antioxidants, foaming agents, organic fillers, and inorganic fillers.

[0088] The preferred lower limit for the thickness of the adhesive layer (Y2) is 200 μm. A thickness of 200 μm or more ensures that the adhesive layer (Y2) has sufficient adhesive strength. A more preferred lower limit for the thickness of the adhesive layer (Y1) is 250 μm, and an even more preferred lower limit is 300 μm. Furthermore, from the viewpoint of increasing the load due to the self-weight of the adhesive sheet, the preferred upper limit for the adhesive layer (Y2) is 1000 μm, and the more preferred upper limit is 500 μm.

[0089] The adhesive sheet of the present invention preferably has a 180° peel force against PTFE on the adhesive layer (Y2) side of less than 5.0 N / 25 mm. Having a 180° peel force against PTFE on the adhesive layer (Y2) side of less than 5.0 N / 25 mm allows for the suppression of contamination of the fluororesin by the adhesive layer (Y2) when lining a can body with fluororesin using the adhesive sheet of the present invention, even if the adhesive layer (Y2) comes into contact with the fluororesin during the lining process. Therefore, workability is further improved when lining a can body with fluororesin using the adhesive sheet of the present invention. A more preferable upper limit for the 180° peel force against PTFE on the adhesive layer (Y2) side of less than 3.0 N / 25 mm, and an even more preferable upper limit of 1.0 N / 25 mm, is used. Furthermore, there is no particular preferred lower limit for the 180° peel force on the PTFE side of the adhesive layer (Y2), but the practical lower limit is 0.01 N / 25 mm. The 180° peel force on the PTFE side of the adhesive layer (Y2) can be measured by the following method. Specifically, first, a 50 μm thick polyimide (PI) film is placed on the adhesive layer (Y1) side of the adhesive sheet, and then the adhesive sheet with the adhesive layer (Y1) side backed is cut to a size of 25 mm wide x 100 mm long by running a 2 kg rubber roller back and forth at a speed of 300 mm / min. Next, the adhesive layer (Y2) side of the cut adhesive sheet is placed on a 2 mm thick polytetrafluoroethylene board (for example, "Yodoflon" manufactured by Yodogawa Hutech Co., Ltd.), and after running a 2 kg rubber roller back and forth at a speed of 300 mm / min, the two are pressed together by applying pressure at 0.1 MPa for 10 minutes in an environment of 120°C to create a laminate. Then, using a tensile testing machine (for example, "Tensilon" manufactured by ORIENTEC), a 180° peel test is performed on the obtained laminate under conditions of 23°C, 50%RH, and a peeling speed of 300 mm / min in accordance with JIS Z 0237. By peeling the adhesive sheet from the polytetrafluoroethylene board, the 180° peel force of the adhesive layer (Y2) relative to PTFE can be measured.

[0090] The adhesive sheet of the present invention has a preferred lower limit of 50 N / 25 mm for the 180° peel force against SUS at 23°C on the adhesive layer (Y2) side. A 180° peel force of 50 N / 25 mm or higher on the adhesive layer (Y2) side at 23°C on SUS improves the adhesive strength of the adhesive layer (Y2). A more preferred lower limit for the 180° peel force of the adhesive layer (Y2) against SUS at 23°C is 70 N / 25 mm, and an even more preferred lower limit is 100 N / 25 mm. Furthermore, there is no particular preferred upper limit for the 180° peel force against SUS at 23°C on the adhesive layer (Y2) side, but the practical upper limit is 500 N / 25 mm. The 180° peel force on SUS at 23°C on the adhesive layer (Y2) can be measured by the following method. Specifically, first, a 50 μm thick polyimide (PI) film is placed on the adhesive layer (Y1) side of the adhesive sheet, and then the adhesive sheet with the adhesive layer (Y1) side backed is cut to a size of 25 mm wide x 100 mm long by using a 2 kg rubber roller to make one back-and-forth motion at a speed of 300 mm / min. Next, the adhesive layer (Y2) side is placed on a SUS plate (SUS304 plate that has been washed with ethanol and then wiped dry), and a laminate is created by pressing it together under pressure of 0.1 MPa for 10 minutes in an environment of 120°C. Then, a 180° peel test is performed on the obtained laminate using a tensile testing machine (for example, "Tensilon" manufactured by ORIENTEC) in accordance with JIS Z 0237, under conditions of 23°C, 50% RH, and a peeling speed of 300 mm / min, and the 180° peel force of the adhesive layer (Y2) side relative to SUS at 23°C can be measured by peeling the adhesive sheet from the SUS plate.

[0091] Methods for adjusting the 180° peel force on SUS at 23°C on the adhesive layer (Y2) side include, for example, changing the type or constituent units of the base polymer (P2) described later (for example, changing the copolymerization ratio or monomer composition of the base polymer (P2)), adjusting the type or content of the tackifying resin (T2) described later, changing the thickness of the adhesive layer (Y2), or changing the substrate.

[0092] The method for manufacturing the adhesive sheet of the present invention is not particularly limited, and examples include the following methods. First, an adhesive solution (a) containing an adhesive composition (X1) is prepared by adding a base polymer (P1), and optionally a tackifying resin (T1), a crosslinking agent, and a solvent. The obtained adhesive solution (a) is applied to the release surface of a release PET film, and the solvent in the solution is completely dried and removed to create a laminated film in which an adhesive layer (Y1) is formed on the release PET film. The prepared laminated film is placed on a substrate so that the adhesive layer (Y1) and the substrate face each other, and cured for 48 hours in an environment of 40°C and 50%RH to obtain an adhesive sheet having the adhesive layer (Y1) on one side of the substrate. Note that the step of applying the adhesive solution (a) to the release surface of the release PET film may be completed in one step, or it may be performed multiple times by applying it on top of the applied adhesive solution. By adjusting the number of application steps, the thickness of the adhesive layer (Y1) can be easily adjusted. Furthermore, an adhesive solution (b) containing an adhesive composition (X2) is prepared by adding a base polymer (P2), and optionally a tackifying resin (T2), a crosslinking agent, and a solvent. The obtained adhesive solution (b) is applied to the release surface of a release PET film, and the solvent in the solution is completely dried and removed to create a laminated film in which an adhesive layer (Y2) is formed on the release PET film. Then, the adhesive sheet having an adhesive layer (Y1) on one side of the substrate and the side of the substrate without the adhesive layer (Y1) are superimposed so that the adhesive layer (Y2) of the laminated film with the adhesive layer (Y2) formed on the release PET film faces each other, and cured for 48 hours in an environment of 40°C and 50%RH, thereby obtaining an adhesive sheet having an adhesive layer (Y1) on one side of the substrate and an adhesive layer (Y2) on the other side of the substrate. The step of applying the adhesive solution (b) to the release treatment surface of the release PET film may be performed only once, or it may be performed multiple times by applying it in layers over the applied adhesive solution. By adjusting the number of application steps, the thickness of the adhesive layer (Y2) can be easily adjusted.

[0093] In manufacturing the adhesive sheet of the present invention, it is preferable to surface treat the substrate. By surface treating the substrate, the interlayer strength of the resulting adhesive sheet is further improved, resulting in higher adhesion to SUS. Examples of the above surface treatments include corona treatment, heat cleaning, and silane treatment.

[0094] The adhesive sheet of the present invention has a lower limit of tensile yield strength of 100 N / cm. Because the adhesive sheet of the present invention has a tensile yield strength of 100 N / cm or higher, it can suppress tearing of the adhesive sheet after bending when bonding the fluororesin to the can body. A preferred lower limit of tensile yield strength for the adhesive sheet of the present invention is 400 N / cm, and a more preferred lower limit is 600 N / cm. Furthermore, while there is no particular preferred upper limit for the tensile yield strength of the adhesive sheet of the present invention, the practical upper limit is 5000 N / cm. The tensile yield strength of the adhesive sheet of the present invention can be measured by the following method. Specifically, a test specimen is prepared by cutting the adhesive sheet to a size of 10 mm wide x 100 mm long with the MD direction as the longer side, and peeling off the separator. In this specification, "MD direction" in this measurement refers to the direction relative to the flow direction of the roll shape, and in the case of a woven fabric, it refers to the direction parallel to the warp threads. The obtained test specimen is subjected to a tensile test using a tensile testing machine (for example, Shimadzu Corporation's "Autograph AGS-X"), with the grip distance set to 50 mm, and pulled at a tensile speed of 300 mm / min until the test specimen breaks. The value of the peak strength at the yield point (stress at the yield point) is obtained from the obtained stress-strain curve, and this peak strength value is taken as the tensile yield strength (N / cm) of the adhesive sheet of the present invention.

[0095] Methods for adjusting the tensile yield strength of the adhesive sheet of the present invention include, for example, changing the type of substrate (e.g., using a woven fabric substrate), changing the type and content ratio of the base polymer (P1) and base polymer (P2) contained in the adhesive layer (Y1) and the adhesive layer (Y2), and adjusting the thickness of the adhesive layer (Y1) and the adhesive layer (Y2) (e.g., reducing the thickness of the adhesive layer to improve flexibility).

[0096] The adhesive sheet of the present invention is not particularly limited in its applications, but is preferably used to protect an adherend, and is particularly preferably used to protect an adherend from chemical solutions. In particular, it is preferably used to bond a tank body to a fluororesin in a chemical solution tank, and is even more preferably used to bond a tank body to a fluororesin in a chemical solution tank for semiconductors or for the chemical industry. The adhesive sheet of the present invention can suppress the lifting of the fluororesin from the can body during bonding and the tearing of the adhesive sheet after bending, thereby enabling a tight bond between the can body and the fluororesin.

[0097] When the adhesive sheet of the present invention has the adhesive layer (Y2), a laminated sheet having a sheet containing fluororesin on the side of the adhesive layer (Y2) in the adhesive sheet of the present invention is also one of the present inventions. Since the laminated sheet of the present invention has a sheet containing fluororesin, by using the laminated sheet of the present invention, it is possible to more easily bond fluororesin for various purposes.

[0098] In the laminated sheet of the present invention, examples of sheets containing the above-mentioned fluororesin include sheets containing polytetrafluoroethylene (PTFE), sheets containing perfluoroalkoxyalkane (PFA), sheets containing perfluoroethylenepropene copolymer (FEP), sheets containing ethylenetetrafluoroethylene copolymer (ETFE), sheets containing polyvinylidene fluoride (PVDF), sheets containing polyvinyl fluoride (PVF), sheets containing polychlorotrifluoroethylene (PCTFE), and sheets containing ethylene chlorotrifluoroethylene copolymer (ECTFE). Among these, sheets containing PTFE are preferred because they have excellent heat resistance and chemical resistance.

[0099] The sheet containing the fluororesin preferably has a surface treatment layer on one surface. By having a surface treatment layer on one surface of the sheet containing the fluororesin, the adhesive strength is further improved when the adhesive layer (Y2) is laminated onto the surface treatment layer of the sheet containing the fluororesin, and the laminated sheet of the present invention can bond the fluororesin more firmly. Examples of the above-mentioned surface treatment layers include sodium etching layers, glass backing layers, atmospheric pressure plasma treatment layers, corona treatment layers, flame treatment layers, and embossing layers. Among these, at least one surface treatment layer selected from the group consisting of sodium etching layers, glass backing layers, and atmospheric pressure plasma treatment layers is preferred.

[0100] Examples of sodium etching treatments in the sodium etching layer mentioned above include the naphthalene method and the ammonia method. Examples of glass backing treatments in the above-mentioned glass backing layer include heat lamination of glass cloth using a PFA sheet as a bonding agent.

[0101] The applications of the laminated sheet of the present invention are not particularly limited, but it can be suitably used to bond fluororesin to dissimilar members for various purposes. More specifically, these various purposes include, for example, promoting sliding of friction surfaces, preventing friction of sliding parts, insulating coating, and protecting adherends from high temperatures or chemical solutions. In particular, it can be suitably used to protect adherends, and especially suitably used to protect adherends from chemical solutions. The adherends to be protected from chemical solutions are not particularly limited, but examples include cans, trays, walls, etc. Specifically, it can be suitably used as a coating material for chemical solution tanks such as chemical solution tanks for semiconductors and chemical solution tanks for the chemical industry, as well as for piping for transporting chemical solutions, as a coating material for electronic equipment components, and as a building material. In particular, the laminated sheet of the present invention can be suitably used for lining (surface treatment covering the inner surface of a can) of a can in a chemical solution tank, and among these, it can be even suitably used for lining a can in a chemical solution tank such as a chemical solution tank for semiconductors or a chemical solution tank for the chemical industry.

[0102] A chemical tank in which the adhesive sheet or laminated sheet of the present invention is attached to the inner surface of a can body is also one of the present inventions. The chemical tank of the present invention allows for strong bonding of fluororesin to the inner surface of the tank body via the adhesive sheet or laminated sheet of the present invention attached to the inner surface of the tank body. Therefore, it is possible to further suppress peeling and lifting of the fluororesin caused by the chemical solution stored in the chemical tank to which the fluororesin is bonded.

[0103] A method for manufacturing a chemical tank, which includes the step of attaching the laminated sheet of the present invention to the inner surface of the tank body of the chemical tank, is also one of the present inventions.

[0104] If the adhesive sheet of the present invention has the adhesive layer (Y2) described above, a method for manufacturing a chemical tank also of the present invention is also one of the present invention, which includes the steps of: preparing a laminated sheet of the present invention by pressing a sheet containing fluororesin onto the adhesive layer (Y2) of the adhesive sheet of the present invention; and attaching the adhesive layer (Y1) of the laminated sheet to the inner surface of the can body of the chemical tank.

[0105] In the process of producing the laminated sheet described above, examples of sheets containing the fluororesin include sheets containing polytetrafluoroethylene (PTFE), sheets containing perfluoroalkoxyalkane (PFA), sheets containing perfluoroethylenepropene copolymer (FEP), sheets containing ethylenetetrafluoroethylene copolymer (ETFE), sheets containing polyvinylidene fluoride (PVDF), sheets containing polyvinyl fluoride (PVF), sheets containing polychlorotrifluoroethylene (PCTFE), and sheets containing ethylene chlorotrifluoroethylene copolymer (ECTFE). Among these, sheets containing PTFE are preferred because they have excellent heat resistance and chemical resistance. [Effects of the Invention]

[0106] According to the present invention, it is possible to provide an adhesive sheet that can suppress the occurrence of fluororesin lifting from the can body during bonding and the tearing of the adhesive sheet after it has been folded, when the adhesive sheet is folded and bonded to the can body. Furthermore, according to the present invention, it is possible to provide a laminated sheet having said adhesive sheet. Moreover, according to the present invention, it is possible to provide a chemical tank to which said adhesive sheet or said laminated sheet has been attached. In addition, according to the present invention, it is possible to provide a method for manufacturing a chemical tank using said adhesive sheet and said laminated sheet. [Modes for carrying out the invention]

[0107] The embodiments of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0108] (Preparation of (meth)acrylic copolymer) (Synthesis Example 1) 100 parts by mass of ethyl acetate was placed in a reactor equipped with a thermometer, stirrer, and condenser, and after purging with nitrogen, the reactor was heated and reflux was started. 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 constituent unit monomers shown in Table 1 was then added dropwise and evenly over 1 hour and 30 minutes to allow the reaction to proceed. 30 minutes after the end of the dropwise addition, 0.1 parts by mass of azobisisobutyronitrile was added, and the polymerization reaction was continued for a further 5 hours. By adding ethyl acetate to the reactor and cooling while diluting, a solution of (meth)acrylic copolymer with a solid content of 25% by mass was obtained. The obtained (meth)acrylic copolymer solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The resulting filtrate was supplied to a gel permeation chromatograph (Waters, 2690 Separations Module), and GPC measurements were performed under conditions of sample flow rate of 1 mL / min and column temperature of 40°C to measure the polystyrene-equivalent molecular weight of the (meth)acrylic copolymer and determine the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn). A GPC KF-806L column (Showa Denko) was used, and a differential refractometer was used as the detector. The results are shown in Table 1.

[0109] (Synthesis Examples 2-3) (Meth)acrylic copolymers were obtained in the same manner as in Synthesis Example 1, except that the monomer mixture was modified as shown in Table 1. The results are shown in Table 1.

[0110] The constituent monomers shown in Table 1 are as follows: BA: n-butyl acrylate 2EHA:2-Ethylhexylacrylate LA: Lauryl acrylate HEA: 2-Hydroxyacrylate AAc: Acrylic acid

[0111] [Table 1]

[0112] (Preparation of tackifying resin) (Synthesis example A) Fifty parts by mass of toluene were added to a reactor equipped with a thermometer, stirrer, and condenser, and after purging with nitrogen, the reactor was heated and reflux was started. After 30 minutes, 2 parts by mass of aluminum chloride (AlCl3) were added while maintaining the toluene at 75°C. A solution of 50 parts by mass of catechol (pyrocatechol) and α-pinene (molar ratio as shown in Table 2) dissolved in 50 parts by mass of toluene was gradually added dropwise over 1 hour and 30 minutes to allow the reaction to proceed. After polymerization for 4 hours, the hydrochloric acid generated from aluminum chloride (AlCl3) was neutralized by cooling while adding 0.1 parts by mass of pyridine to the reactor. The precipitate formed by neutralization was filtered, and after liquid-liquid extraction of the obtained filtrate, the toluene was evaporated to obtain a solid tackifying resin (Synthesis Example A). Regarding the obtained tackifying resin (synthesis example A): 1 ¹H-NMR measurements were performed to confirm that the tackifying resin (T1-1) is a copolymer having structural units derived from catechol (pyrocatechol) and structural units derived from α-pinene (a copolymer having structural units derived from catechol (pyrocatechol) in the main chain skeleton or at the ends of the main chain skeleton). The obtained tackifying resin (synthesis example A) was dissolved in tetrahydrofuran, and the resulting 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 measurements were performed under conditions of sample flow rate of 1 mL / min and column temperature of 40°C to measure the polystyrene-equivalent molecular weight of the tackifying resin (T1-1) and determine the weight-average molecular weight (Mw). A GPC KF-802.5L column (Showa Denko) was used, and a differential refractometer was used as the detector. The results are shown in Table 2.

[0113] (Measurement of the percentage of bio-derived carbon in tackifying resin (synthesis example A)) The bio-derived carbon content of the obtained tackifying resin (synthesis example A) was measured according to ASTM D6866-22. The results are shown in Table 2.

[0114] [Table 2]

[0115] (Example 1) (1) Preparation of adhesive sheets To 100 parts by mass of the solid content of the (meth)acrylic copolymer (Synthesis Example 1) obtained as the base polymer (P1), 20 parts by mass of rosin ester resin (Arakawa Chemical Industries, Ltd., "Pine Crystal KE-359") and 10 parts by mass of terpene phenol resin (Yasuhara Chemical Co., Ltd., "YS Polystar G150") were added as tackifying resins (T1). Furthermore, 30 parts by mass of ethyl acetate (Fuji Chemical Co., Ltd.) and 1.0 part by mass of isocyanate crosslinking agent (Covestro, Inc., "Desmodule L-75") were added, and the mixture was thoroughly stirred to obtain an adhesive solution (a) containing the adhesive composition (X1). The obtained adhesive solution (a) was applied to the release surface of a 75 μm thick release PET film (Toyo Cloth Co., Ltd., "SP3000"), and dried at 100°C for 5 minutes to form a 200 μm thick adhesive layer (Y1) on the release PET film, thereby producing a laminated film (a). A 100 μm thick glass cloth (Arisawa Seisakusho Co., Ltd., "1031NT-1270 S640") was prepared as the base material. The prepared laminated film was placed on top of the base material so that the adhesive layer (Y1) faced the base material, and then cured by heating at 40°C for 48 hours. This resulted in a laminate having the base material and the adhesive layer (Y1) on one side of the base material. Furthermore, to 100 parts by mass of the solid content of the (meth)acrylic copolymer (Synthesis Example 1) obtained as the base polymer (P2), 20 parts by mass of rosin ester resin (Arakawa Chemical Industries, Ltd., "Pine Crystal KE-359") and 10 parts by mass of terpene phenol resin (Yasuhara Chemical Co., Ltd., "YS Polystar G150") were added. In addition, 30 parts by mass of ethyl acetate (Fuji Chemical Co., Ltd.) and 1.0 part by mass of isocyanate crosslinking agent (Covestro, Inc., "Desmodule L-75") were added, and the mixture was thoroughly stirred to obtain an adhesive solution (b) containing the adhesive composition (X2). The obtained adhesive solution (b) was applied to the release surface of a 75 μm thick release PET film (Toyo Cloth Co., Ltd., "SP3000"), and dried at 100°C for 5 minutes to form a 50 μm thick adhesive layer (Y2) on the release PET film, thereby producing a laminated film (b). In a laminate having a substrate and an adhesive layer (Y1) on one side of the substrate, the side of the substrate without the adhesive layer (Y1) and the adhesive layer (Y2) of the laminated film (b) were superimposed so that they faced each other, and cured for 48 hours in an environment of 40°C and 50%RH to obtain 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.

[0116] (2) Measurement of 180° peel force against SUS at 23°C on the adhesive layer (Y1) side. The obtained adhesive sheet was then backed by placing a 50 μm thick polyimide (PI) film on top of the adhesive layer (Y2) and rolling a 2 kg rubber roller back and forth once at a speed of 300 mm / min. After that, it was cut to a size of 25 mm wide x 100 mm long. Next, the cut adhesive sheet was placed with the adhesive layer (Y1) side on top of a 1 mm thick SUS plate (SUS304 plate that had been washed with ethanol and then wiped dry). A 2 kg rubber roller was used to roll the sheets back and forth once at a speed of 300 mm / min, and then the sheets were pressed together by applying pressure at 0.1 MPa for 10 minutes in an environment of 120°C to create a laminate. The obtained laminates were subjected to a 180° peel test using a tensile testing machine (ORIENTEC, "Tensilon") in accordance with JIS Z 0237, under conditions of 23°C, 50% RH, and a peeling speed of 300 mm / min. The 180° peel force of the adhesive layer (Y1) relative to the SUS at 23°C was measured by peeling the adhesive sheet from the SUS plate. The results are shown in Table 3.

[0117] (3) Measurement of the 180° peel force on the PTFE on the adhesive layer (Y1) side. The obtained adhesive sheet was then backed by placing a 50 μm thick polyimide (PI) film on top of the adhesive layer (Y2) and running a 2 kg rubber roller back and forth at a speed of 300 mm / min once. After that, it was cut to a size of 25 mm wide x 100 mm long. The adhesive layer (Y1) side of the cut adhesive sheet was pressed onto a 2 mm thick polytetrafluoroethylene sheet (Yodogawa Hutech Co., Ltd., "Yodoflon") by running a 2 kg rubber roller back and forth at a speed of 300 mm / min once. A laminate was then fabricated by further pressing it under pressure at 0.1 MPa for 10 minutes in an environment of 120°C. The obtained laminates were subjected to a 180° peel test using a tensile testing machine (ORIENTEC, "Tensilon") in accordance with JIS Z 0237, under conditions of 23°C, 50% RH, and a peeling speed of 300 mm / min. The 180° peel force of the adhesive layer (Y1) against PTFE was measured by peeling the adhesive layer (Y1) from the polytetrafluoroethylene film. The results are shown in Table 3.

[0118] (4) Measurement of 180° peel force against SUS at 23°C on the adhesive layer (Y2) side. The obtained adhesive sheet was then backed by placing a 50 μm thick polyimide (PI) on top of the adhesive layer (Y1) and rolling a 2 kg rubber roller back and forth once at a speed of 300 mm / min. After that, it was cut to a size of 25 mm wide x 100 mm long. Next, the cut adhesive sheet was placed with the adhesive layer (Y1) side facing a 1 mm thick SUS plate (SUS304 plate that had been washed with ethanol and then wiped dry), and a 2 kg rubber roller was used to roll it back and forth once at a speed of 300 mm / min. Finally, a laminate was created by pressing it under pressure at 0.1 MPa for 10 minutes in an environment of 120°C. The obtained laminates were subjected to a 180° peel test using a tensile testing machine (ORIENTEC, "Tensilon") in accordance with JIS Z 0237, under conditions of 23°C, 50% RH, and a peeling speed of 300 mm / min. The 180° peel force of the adhesive layer (Y2) relative to the SUS at 23°C was measured by peeling the adhesive sheet from the SUS plate. The results are shown in Table 3.

[0119] (5) Measurement of the 180° peel force against the PTFE on the adhesive layer (Y2) side. The obtained adhesive sheet was then backed by placing a 50 μm thick polyimide (PI) film on top of the adhesive layer (Y1) and running a 2 kg rubber roller back and forth at a speed of 300 mm / min once. After that, it was cut to a size of 25 mm wide x 100 mm long. The adhesive layer (Y2) side of the cut adhesive sheet was pressed onto a 2 mm thick polytetrafluoroethylene sheet (Yodogawa Hutech Co., Ltd., "Yodoflon") by running a 2 kg rubber roller back and forth at a speed of 300 mm / min once. A laminate was then fabricated by further pressing it under pressure at 0.1 MPa for 10 minutes in an environment of 120°C. The obtained laminates were subjected to a 180° peel test using a tensile testing machine (ORIENTEC, "Tensilon") in accordance with JIS Z 0237, under conditions of 23°C, 50% RH, and a peeling speed of 300 mm / min. The 180° peel force of the adhesive layer (Y2) against PTFE was measured by peeling the adhesive layer (Y2) from the polytetrafluoroethylene film. The results are shown in Table 3.

[0120] (6) Measurement of the tensile yield strength of the adhesive sheet Test specimens were prepared by cutting the adhesive sheet to a size of 10 mm wide x 100 mm long, with the MD direction as the longer side, and peeling off the separator. Tensile tests were performed on the obtained test specimens using a tensile testing machine (Shimadzu Corporation, "Autograph AGS-X"), with the grip distance set to 50 mm, and pulling the specimen at a tensile speed of 300 mm / min until it broke. The peak strength (stress at the yield point) was obtained from the resulting stress-strain curve, and this peak strength value was defined as the tensile yield strength (N / cm) of the adhesive sheet. The results are shown in Table 3.

[0121] (Examples 2-18, Comparative Examples 1-7) In the above-described "(1) Preparation of adhesive sheet," an adhesive sheet was prepared and measured in the same manner as in Example 1, except that the composition of the adhesive composition (X1), the thickness of the adhesive layer (Y1), the type and thickness of the substrate, the composition of the adhesive composition (X2), and the thickness of the adhesive layer (Y2) were as shown in Tables 3 to 5. The results are shown in Tables 3 to 5.

[0122] <Rating> The obtained adhesive sheets were evaluated using the following method. The results are shown in Tables 6-8.

[0123] (Lifting of fluororesin after adhesive sheet application) The adhesive sheet obtained was bonded to a polytetrafluoroethylene (PTFE) plate (manufactured by Yoshida SKT Co., Ltd., TEFPASS etching sheet, 2 mm thick) with a sodium etching treatment on its surface. After pressing it down by running a 2 kg rubber roller back and forth at a speed of 300 mm / min once, the adhesive sheet was cut to a size of 210 mm wide x 297 mm long. The adhesive layer (Y1) of the cut adhesive sheet was bonded along the circumferential direction of the inner side surface of a head plate (manufactured by Ohama Press Co., Ltd., "10% dish-type head plate"), and the lifting of the PTFE plate was visually observed. If lifting of the PTFE plate was observed, the adhesive layer (Y1) of the adhesive sheet was bonded to the prepared cut adhesive sheet again, while heating the pressed PTFE plate with a gas burner, along the circumferential direction of the inner side surface of the head plate (manufactured by Ohama Press Co., Ltd., "10% dish-type head plate"), and the lifting of the PTFE plate was visually observed again. The lifting of the fluororesin after adhesive sheet application was evaluated according to the following criteria. ◎: No lifting occurred when the adhesive was bonded without heating. ○: When bonded without heating, lifting occurred, but when bonded while heating, lifting did not occur. ×: Lifting occurred even when the pieces were bonded together while heating. If the evaluation is satisfactory, it will be possible to suppress the occurrence of fluororesin lifting from the can body when bonding the fluororesin to the can body using an adhesive sheet.

[0124] (Tearing of the adhesive sheet after folding) The obtained adhesive sheet was cut to a size of 25 mm wide x 100 mm long, and the release PET film on both sides was peeled off. The adhesive layer (Y2) was then bonded to a polytetrafluoroethylene board (TEFPASS etching sheet, manufactured by Yoshida SKT Co., Ltd.) that was 50 mm wide, 125 mm long, and 2 mm thick, with a sodium etching treatment on its surface. At this time, the adhesive sheet was adjusted to be located in the center of the length of the polytetrafluoroethylene board. A 2 kg rubber roller was passed back and forth once on the polytetrafluoroethylene board at a speed of 300 mm / min, and then left to stand at 23°C for 24 hours to create a laminate. The resulting laminate was then bent by manually applying bending stress in the length direction of the laminate so that the PTFE board was on the inside. The bending angle was increased by 30° per second, and the tearing of the adhesive sheet was observed when the laminate was bent to 90° and when the laminate was bent to 180°. The tearing of the adhesive sheet after bending was evaluated according to the following criteria. ◎: No tearing of the adhesive sheet occurred even when the laminate was bent 180°. ○: When the laminate was bent at 90°, no tearing occurred in the adhesive sheet, but when the laminate was bent at 180°, tearing occurred in the adhesive sheet. ×: When the laminate was bent 90°, the adhesive sheet tore. If the evaluation is satisfactory, it will be possible to suppress the tearing of the adhesive sheet after it has been folded when bonding the fluororesin and the can body using the adhesive sheet.

[0125] (Adhesive residue on PTFE) After the 180° peel test of the adhesive sheet in "(3) Measurement of 180° peel force on PTFE on the adhesive layer (Y1) side" described above, the surface of the PTFE board after peeling the adhesive sheet was visually observed, and the amount of adhesive residue on the PTFE was evaluated according to the following criteria. ○: When no adhesive residue is present on the surface of the PTFE board after the adhesive sheet has been removed. ×: If adhesive residue is present on the surface of the PTFE board after the adhesive sheet has been removed. Even if the evaluation result is "×", it can still be used without problems depending on the application.

[0126] [Table 3]

[0127] [Table 4]

[0128] [Table 5]

[0129] [Table 6]

[0130] [Table 7]

[0131] [Table 8] [Industrial applicability]

[0132] According to the present invention, it is possible to provide an adhesive sheet that can suppress the occurrence of fluororesin lifting from the can body during bonding and the tearing of the adhesive sheet after it has been folded, when the adhesive sheet is folded and bonded to the can body. Furthermore, according to the present invention, it is possible to provide a laminated sheet having said adhesive sheet. Moreover, according to the present invention, it is possible to provide a chemical tank to which said adhesive sheet or said laminated sheet has been attached. In addition, according to the present invention, it is possible to provide a method for manufacturing a chemical tank using said adhesive sheet and said laminated sheet.

Claims

1. An adhesive sheet having a base material and an adhesive layer (Y1) formed on one surface of the base material using an adhesive composition (X1), The adhesive sheet has a 180° peel force of 50 N / 25 mm or more on the adhesive layer (Y1) side against SUS at 23°C. The adhesive sheet has a tensile yield strength of 100 N / cm or more. An adhesive sheet characterized by the following features.

2. The adhesive sheet according to claim 1, wherein the substrate is made of a substrate having a mesh structure.

3. The adhesive sheet according to claim 2, wherein the base material having the mesh structure is a woven fabric base material.

4. The adhesive sheet according to claim 3, wherein the base material of the fabric is a base material woven in a twill weave or satin weave.

5. The adhesive sheet according to claim 1, 2, 3, or 4, wherein the substrate having the mesh structure is composed of at least one selected from the group consisting of glass cloth, carbon cloth, alumina cloth, and metal mesh.

6. The adhesive sheet according to claim 1, 2, 3, or 4, wherein the thickness of the substrate is 150 μm or more.

7. The adhesive sheet according to claim 1, 2, 3, or 4, wherein the thickness of the adhesive layer (Y1) is 200 μm or more.

8. The adhesive sheet according to claim 1, 2, 3, or 4, wherein the 180° peel force on the PTFE side of the adhesive layer (Y1) is less than 5.0 N / 25 mm.

9. The adhesive composition (X1) contains a base polymer (P1), The base polymer (P1) includes at least one selected from the group consisting of (meth)acrylic copolymers, styrene elastomers, and synthetic rubbers. The adhesive sheet according to claim 1, 2, 3, or 4.

10. The adhesive sheet according to claim 1, 2, 3, or 4, wherein the adhesive composition (X1) contains a tackifying resin (T1).

11. The adhesive sheet according to claim 10, wherein the tackifying resin (T1) comprises at least one tackifying resin selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins.

12. The adhesive composition (X1) contains a base polymer (P1), The adhesive sheet according to claim 10, wherein the content of the tackifying resin (T1) is 10 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the base polymer (P1).

13. The adhesive sheet according to claim 1, 2, 3, or 4, wherein the adhesive composition (X1) contains a silane coupling agent.

14. The adhesive sheet according to claim 13, wherein the silane coupling agent comprises a silane coupling agent having at least one functional group selected from the group consisting of epoxy group, amino group, vinyl group, acrylic group, methacrylic group, isocyanate group, isocyanurate group, styryl group, ureido group, acid anhydride group, and mercapto group.

15. The adhesive composition (X1) contains a base polymer (P1), The adhesive sheet according to claim 13, wherein the content of the silane coupling agent is 0.1 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the base polymer (P1).

16. Furthermore, the adhesive sheet according to claim 1, further comprising an adhesive layer (Y2) formed on the other surface of the substrate using an adhesive composition (X2).

17. The adhesive sheet according to claim 16, wherein the thickness of the adhesive layer (Y2) is 200 μm or more.

18. The adhesive sheet according to claim 16 or 17, wherein the 180° peel force on the PTFE side of the adhesive layer (Y2) is less than 5.0 N / 25 mm.

19. The adhesive composition (X2) contains a base polymer (P2), The base polymer (P2) includes at least one selected from the group consisting of (meth)acrylic copolymers, styrene elastomers, and synthetic rubbers. The adhesive sheet according to claim 16 or 17.

20. The adhesive sheet according to claim 1, 2, 3, or 4, used for lining a tank body in a chemical tank.

21. A laminated sheet having a sheet containing fluororesin on the adhesive layer (Y2) side, according to claim 16.

22. The laminated sheet according to claim 21, wherein the sheet containing the fluororesin has at least one surface treatment layer selected from the group consisting of a sodium etching layer, a glass backing layer, and an atmospheric pressure plasma treatment layer on one of its surfaces.

23. A laminated sheet according to claim 21, used to protect an adherend.

24. A laminated sheet according to claim 23, used to protect an adherend from a chemical solution.

25. A chemical tank having an adhesive sheet according to claim 1, 2, 3, or 4, or a laminated sheet according to claim 24, attached to the inner surface of a can.

26. A method for manufacturing a chemical tank, comprising the step of attaching the laminated sheet described in claim 24 to the inner surface of the tank body of the chemical tank.

27. A method for manufacturing a chemical tank, comprising the steps of: manufacturing a laminated sheet using the adhesive sheet described in claim 16 or 17, and pressing a sheet containing fluororesin onto the adhesive layer (Y2); and attaching the adhesive layer (Y1) of the laminated sheet to the inner surface of the tank body of the chemical tank.

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