Adhesive composition, adhesive tape, laminated sheet, chemical solution tank, and method for manufacturing a chemical solution tank.

Abstract

The present invention provides a (meth)acrylic adhesive composition that facilitates the bonding of fluororesins and enables the creation of a thick, uniform coating film without placing a significant burden on the environment. It also provides an adhesive tape formed using the adhesive composition. Furthermore, it provides a laminated sheet having the adhesive tape, and a chemical tank to which the adhesive tape or laminated sheet is attached. In addition, it provides a method for manufacturing a chemical tank using the adhesive tape and the laminated sheet. [Solution] An adhesive composition comprising a base polymer and a tackifying resin, wherein the base polymer comprises a (meth)acrylic copolymer, the (meth)acrylic copolymer has a weight-average molecular weight of less than 400,000, and the tackifying resin comprises a tackifying resin whose constituent units are aromatic rings having side chain groups selected from hydroxyl groups, COOH groups, ether groups, and amino groups.

Description

[Technical Field]

[0001] This invention relates to an adhesive composition. Furthermore, it relates to an adhesive tape formed using the adhesive composition. Moreover, it relates to a laminated sheet having the adhesive tape, and to a chemical tank to which the adhesive tape or the laminated sheet is attached. In addition, it relates to a method for manufacturing a chemical tank using the adhesive tape and the laminated sheet. [Background technology]

[0002] Conventionally, adhesive tape has been widely used to fix various components. Specifically, for example, adhesive tape is used to adhere a cover panel to protect the surface of a portable electronic device to a touch panel module or display panel module, or to bond a touch panel module to a display panel module. In addition to high adhesiveness, adhesive tape used to fix such components is required to have functions such as heat resistance, thermal conductivity, and impact resistance, depending on the environment in which it is used (for example, Patent Documents 1 to 3). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-052050 [Patent Document 2] Japanese Patent Publication No. 2015-021067 [Patent Document 3] Japanese Patent Publication No. 2015-120876 [Overview of the project] [Problems that the invention aims to solve]

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

[0005] Generally, fluororesins are used to bond dissimilar materials, but fluororesins do not exhibit good adhesion to adhesive tapes, making bonding with general adhesive tapes difficult. Therefore, methods for bonding fluororesins to dissimilar materials typically involve applying a liquid adhesive to a fluororesin surface treated for easy adhesion, bonding via adhesive tape using a silicone-based adhesive, or treating the surface of the fluororesin with an alkaline hydrophilic solution to improve the adhesive strength of the adhesive. However, each of these methods presents challenges: the process is complicated when using liquid adhesives, the components to be bonded can be contaminated by the volatilization or penetration of low molecular weight components when using silicone-based adhesives, and environmental pollution occurs due to wastewater generated during the hydrophilic treatment when using alkaline hydrophilic solutions. Furthermore, adhesives are typically used by applying an adhesive composition and then drying it to form an adhesive layer. To increase the thickness of the adhesive layer in order to improve adhesion, it is necessary to apply the adhesive composition thickly (thick coating). However, such thick coating presents challenges such as equipment limitations, the generation of air bubbles during the drying process after application, and increased solvent usage, which places a burden on the environment.

[0006] The present invention provides a (meth)acrylic adhesive composition that can easily bond fluororesins and obtain a thick, uniform coating film without placing a significant burden on the environment. The present invention also provides an adhesive tape formed using the adhesive composition. Furthermore, the present invention provides a laminated sheet having the adhesive tape, and a chemical tank to which the adhesive tape or the laminated sheet is attached. In addition, the present invention provides a method for manufacturing a chemical tank using the adhesive tape and the laminated sheet. [Means for solving the problem]

[0007] The present disclosure 1 is an adhesive composition containing a base polymer and a tackifier resin, wherein the base polymer includes a (meth)acrylic copolymer, the (meth)acrylic copolymer has a weight average molecular weight of less than 400,000, and the tackifier resin is a tackifier resin (T1-1) having at least one structural unit (A) selected from the group consisting of a structural unit (A-1), a structural unit (A-1'), a structural unit (A-2), a structural unit (A-2'), a structural unit (A-3), a structural unit (A-3'), a structural unit (A-4), and a structural unit (A-4') represented by the following formula. The present disclosure 2 is the adhesive composition of the present disclosure 1, wherein the (meth)acrylic copolymer has a structural unit derived from a polar functional group-containing monomer, and the polar functional group-containing monomer includes at least one selected from the group consisting of a carboxy group-containing monomer and a hydroxy group-containing monomer. The present disclosure 3 is the adhesive composition of the present disclosure 1 or 2, wherein the (meth)acrylic copolymer has a structural unit derived from an alkyl (meth)acrylate, and the alkyl (meth)acrylate includes an alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms at the ester terminal. The present disclosure 4 is the adhesive composition of the present disclosure 1, 2 or 3, wherein the tackifier resin (T1-1) further has a structural unit (B) derived from at least one monomer (b) selected from the group consisting of a terpene-based monomer and a vinyl-based monomer. The present disclosure 5 is the adhesive composition of the present disclosure 1, 2, 3 or 4, wherein the tackifier resin (T1-1) has a softening temperature of 50°C or higher and 90°C or lower. The present disclosure 6 is the adhesive composition of the present disclosure 1, 2, 3, 4 or 5, wherein the content of the tackifier resin (T1-1) with respect to 100 parts by mass of the base polymer is 5 parts by mass or more and 30 parts by mass or less. The present disclosure 7 is the adhesive composition of the present disclosure 1, 2, 3, 4, 5 or 6, wherein the tackifier resin further includes at least one tackifier resin (T1-2) selected from the group consisting of a rosin ester resin, a terpene resin, a terpene phenol resin, and a petroleum resin. The present disclosure 8 is the adhesive composition of any one of the present disclosures 1, 2, 3, 4, 5, 6 or 7, wherein the content of the entire tackifier resin with respect to 100 parts by mass of the base polymer is 10 parts by mass or more and 80 parts by mass or less. The present disclosure 9 is the adhesive composition of any one of the present disclosures 1, 2, 3, 4, 5, 6, 7 or 8, further containing a crosslinking agent. The present disclosure 10 is the adhesive composition of the present disclosure 9, wherein the crosslinking agent contains at least one selected from the group consisting of an isocyanate - based crosslinking agent and an epoxy - based crosslinking agent. The present disclosure 11 is the adhesive composition of the present disclosure 9, wherein the content of the crosslinking agent with respect to 100 parts by mass of the base polymer is 2 parts by mass or more and 15 parts by mass or less. The present disclosure 12 is the adhesive composition of any one of the present disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, further containing a solvent. The present disclosure 13 is the adhesive composition of the present disclosure 12, wherein the solid content concentration is 50% by mass or more and 80% by mass or less. The present disclosure 14 is the adhesive composition of any one of the present disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or 13, for the adhesive composition not containing a crosslinking agent, the viscosity measured under the conditions of using a B - type viscometer at 23°C and 10 rpm is 0.1 Pa·s or more and 15 Pa·s or less. The present disclosure 15 is an adhesive tape having an adhesive layer (Y1) formed using the adhesive composition of any one of the present disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14. The present disclosure 16 is the adhesive tape of the present disclosure 15, wherein the gel fraction of the adhesive layer (Y1) is 1 mass% or more and 60 mass% or less. The present disclosure 17 is the adhesive tape of the present disclosure 15 or 16, wherein the thickness of the adhesive layer (Y1) is 100 μm or more and 1000 μm or less. The present disclosure 18 is the adhesive tape of any one of the present disclosures 15, 16 or 17, further having a base material. The present disclosure 19 is the adhesive tape of the present disclosure 18, wherein the base material contains at least one selected from the group consisting of a polyester resin, a polyimide resin, a polyether resin, a polyolefin resin, a polyurethane resin, a metal, a glass fiber, and a carbon fiber. Disclosure 20 is an adhesive tape according to Disclosure 18 or 19, wherein the substrate is a substrate of at least one shape selected from the group consisting of nonwoven fabric and woven fabric. Disclosure 21 is an adhesive tape according to Disclosure 18, 19, or 20, having the above-mentioned substrate, the above-mentioned adhesive layer (Y1) on one side of the substrate, and the adhesive layer (Y2) formed on the other side of the substrate using an adhesive composition (X2). Disclosure 22 is an adhesive tape according to Disclosure 21, wherein the adhesive layer (Y2) has a thickness of 50 μm or more and 500 μm or less. Disclosure 23 is an adhesive tape according to Disclosure 21 or 22, 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 and styrene-based elastomers. Disclosure 24 is an adhesive tape according to Disclosure 21, 22, or 23, wherein the adhesive composition (X2) contains a tackifying resin (T2), and the tackifying resin (T2) contains at least one tackifying resin selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins. Disclosure 25 is an adhesive tape according to Disclosure 21, 22, 23, or 24, wherein the adhesive composition (X2) contains a silane coupling agent. Disclosure 26 is an adhesive tape of Disclosure 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 used for lining the body of a chemical tank for semiconductors or chemical tanks for the chemical industry. Disclosure 27 is a laminated sheet having a sheet containing fluororesin on the adhesive layer (Y1) side of the adhesive tape of Disclosure 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or 26. Disclosure 28 is a laminated sheet of Disclosure 27 used to protect an adherend. Disclosure 29 is a laminated sheet of Disclosure 28 used to protect an adherend from a chemical solution. Disclosure 30 is a chemical tank in which the adhesive tape of Disclosure 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26 or the laminated sheet of Disclosure 27, 28 or 29 is attached to the inner surface of the can body. Disclosure 31 is a method for manufacturing a chemical tank for semiconductors or a chemical tank for the chemical industry, which includes the step of attaching the adhesive tape of Disclosure 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or 26 to the inner surface of the tank body of the chemical tank. Disclosure 32 is a method for manufacturing a chemical tank, comprising the steps of: preparing a laminated sheet according to Disclosure 27, 28, or 29 by pressing a sheet containing fluororesin onto the adhesive layer (Y1) of the adhesive tape according to Disclosure 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, or 26; and attaching the adhesive layer (Y2) of the laminated sheet to the inner surface of the can body of the chemical tank.

[0008] [ka]

[0009] [ka]

[0010] [ka]

[0011] [ka]

[0012] In the formula, R 1 ~R 7* represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group, respectively. n and l each represent an integer between 2 and 4, and n' and l' each represent an integer between 2 and 5. m and k each represent an integer between 1 and 4, and m' and k' each represent an integer between 1 and 5. * represents a linking part. The present invention will be described in detail below.

[0013] The present inventors have discovered that by using a (meth)acrylic copolymer having a weight-average molecular weight below a specific value as a base polymer in combination with a tackifying resin having a specific structure, it is possible to obtain a (meth)acrylic adhesive composition that facilitates the bonding of fluororesins and allows for the creation of a thick, uniform coating film without placing a significant burden on the environment, thus completing the present invention.

[0014] The adhesive composition of the present invention contains a base polymer. The above base polymer includes a (meth)acrylic copolymer. 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.

[0015] The above (meth)acrylic copolymer has a weight-average molecular weight (Mw) of less than 400,000. By including the above (meth)acrylic copolymer, which has a weight-average molecular weight (Mw) of less than 400,000, in combination with the tackifying resin (T1-1) described later, the adhesive composition of the present invention can easily bond fluororesins and obtain a thick, uniform coating film without placing a large burden on the environment. The preferred upper limit for the weight-average molecular weight (Mw) of the above (meth)acrylic copolymer is 350,000, and the more preferred upper limit is 300,000. Furthermore, a preferred lower limit for the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 50,000. A weight-average molecular weight (Mw) of 50,000 or more improves the bulk cohesive force of the adhesive layer formed using the adhesive composition of the present invention, thereby further improving the adhesive strength. A more preferred lower limit for the weight-average molecular weight (Mw) of the (meth)acrylic copolymer is 100,000, and an even more preferred lower limit is 150,000. In this specification, the term "adhesion" refers not only to a permanent bonding phenomenon but also to a temporary bonding phenomenon called "tackiness."

[0016] The preferred lower limit for the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the above (meth)acrylic copolymer (molecular weight distribution (Mw / Mn)) is 1.05, and the preferred upper limit is 10.0. When the molecular weight distribution (Mw / Mn) of the above (meth)acrylic copolymer is 1.05 or higher, the adhesive layer formed using the adhesive composition of the present invention becomes more flexible, and the adhesion to fluororesin is further improved. When the molecular weight distribution (Mw / Mn) of the above (meth)acrylic copolymer is 10.0 or lower, the proportion of low molecular weight components is suppressed, the bulk cohesive force of the adhesive layer formed using the adhesive composition of the present invention is improved, and the adhesive strength is further improved. The more preferred upper limit for the molecular weight distribution (Mw / Mn) of the above (meth)acrylic copolymer is 9.0, the even more preferred upper limit is 8.0, and the even more preferred upper limit is 7.0.

[0017] In this specification, weight-average molecular weight (Mw) and number-average molecular weight (Mn) refer to the weight-average molecular weight (Mw) 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 obtained 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).

[0018] Methods for adjusting the weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the above (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. More specifically, methods include changing the type and amount of polymerization initiator and monomer concentration during the polymerization reaction, adding a small amount of chain transfer agent such as dodecyl mercaptan, controlling chain transfer to the solvent by changing the type of polymerization reaction solvent, and changing the temperature and time during the reaction.

[0019] The (meth)acrylic copolymer preferably has structural units derived from a polar functional group-containing monomer. Having structural units derived from a polar functional group-containing monomer in the (meth)acrylic copolymer increases the bulk cohesive force of the adhesive layer formed using the adhesive composition of the present invention, thereby further improving the adhesive strength.

[0020] The above polar functional group is reactive, such as through crosslinking reactions, and preferably at least one selected from the group consisting of carboxyl groups, hydroxyl groups, amino groups, and epoxy groups. In particular, one selected from the group consisting of carboxyl groups and hydroxyl groups is more preferred because it can contribute to improving the adhesive strength of the resulting adhesive tape. That is, the above polar functional group-containing monomer preferably contains at least one selected from the group consisting of carboxyl group-containing monomers and hydroxyl group-containing monomers. Examples of the above-mentioned carboxyl group-containing monomers include (meth)acrylic acid. Examples of the hydroxyl group-containing monomers mentioned above include 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate. Examples of polar functional group-containing monomers (epoxy group-containing monomers) having an epoxy group as the polar functional group include glycidyl (meth)acrylate. The above-mentioned monomers containing polar functional groups may be used individually or in combination of two or more types. In this specification, "(meth)acrylate" means acrylate or methacrylate.

[0021] In the above (meth)acrylic copolymer, the preferred lower limit for the content of constituent units derived from the carboxyl group-containing monomer is 0.01% by mass, and the preferred upper limit is 3.0% by mass. By having the content of constituent units derived from the carboxyl group-containing monomer within this range, the cohesive force of the bulk of the adhesive layer formed using the adhesive composition of the present invention can be appropriately adjusted, thereby further improving the adhesive strength. A more preferred lower limit for the content of constituent units derived from the carboxyl group-containing monomer is 0.05% by mass, and a more preferred upper limit is 2.0% by mass.

[0022] In the above (meth)acrylic copolymer, the preferred lower limit for the content of constituent units derived from the above hydroxyl group-containing monomer is 0.01% by mass, and the preferred upper limit is 3.0% by mass. By having the content of constituent units derived from the above hydroxyl group-containing monomer within this range, the cohesive force of the bulk of the adhesive layer formed using the adhesive composition of the present invention can be appropriately adjusted, thereby further improving the adhesive strength. A more preferred lower limit for the content of constituent units derived from the above hydroxyl group-containing monomer is 0.05% by mass, and a more preferred upper limit is 2.0% by mass.

[0023] In the above (meth)acrylic copolymer, the preferred lower limit for 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. By having the total content of constituent units derived from the above polar functional group-containing monomer within this range, the cohesive force of the bulk of the adhesive layer formed using the adhesive composition of the present invention can be appropriately adjusted, thereby further improving the adhesive strength. A more preferred lower limit for the total content of constituent units derived from the above polar functional group-containing monomer is 0.1% by mass, and a more preferred upper limit is 3.0% by mass.

[0024] The above (meth)acrylic copolymer preferably has constituent units derived from alkyl (meth)acrylate. The alkyl (meth)acrylate described above preferably includes an alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms at its ester terminus. That is, the (meth)acrylic copolymer preferably has structural units derived from alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms at its ester terminus. By having structural units derived from alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms at its ester terminus, the flexibility of the adhesive layer formed using the resulting adhesive composition is further improved, and thus the adhesion to fluororesin is further improved. In particular, the alkyl (meth)acrylate described above is more preferably an alkyl (meth)acrylate having a linear alkyl group with 7 or more carbon atoms at its ester terminus. Furthermore, from the viewpoint of uniformity of the coating film when the resulting adhesive composition is applied thickly, the (meth)acrylic copolymer preferably has structural units derived from alkyl (meth)acrylate having an alkyl group with 12 or fewer carbon atoms at its ester terminus, and more preferably has structural units derived from alkyl (meth)acrylate having an alkyl group with 8 or fewer carbon atoms at its ester terminus. In this specification, the term "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.

[0025] Examples of alkyl (meth)acrylates having an alkyl group with 6 or more carbon atoms at the ester terminus include n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 1-methylheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, arachidyl (meth)acrylate, esters of 5,7,7-trimethyl-2-(1,3,3-trimethylbutyl)octanol-1 with (meth)acrylic acid, and esters of (meth)acrylic acid with an alcohol having 1 or 2 methyl groups in a linear main chain and a total of 18 carbon atoms. The alkyl (meth)acrylates having an alkyl group with 6 or more carbon atoms at the ester end may be used alone or in combination of two or more types.

[0026] The preferred lower limit for the content of constituent units derived from alkyl (meth)acrylate having an alkyl group with 6 or more 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 6 or more 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 formed using the adhesive composition of the present invention is further improved, and the adhesion strength of the adhesive layer to the fluororesin is further improved. A more preferred lower limit for the content of constituent units derived from alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms at its ester terminus is 90% by mass, and an even more preferred lower limit is 95% by mass. Furthermore, from the viewpoint of the bulk cohesive force of the adhesive layer formed using the adhesive composition of the present invention, the preferred upper 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 is 99.5% by mass, and the more preferred upper limit is 99% by mass.

[0027] The alkyl (meth)acrylate described above may include other alkyl (meth)acrylates other than the alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms at its ester terminus. Examples of the other alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and the like. The above-mentioned other alkyl (meth)acrylates may be used individually or in combination of two or more types.

[0028] 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.

[0029] The preferred lower limit for 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 resulting adhesive tape exhibiting superior adhesion to fluororesin. A more preferred lower limit for 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.

[0030] 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.

[0031] 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 types.

[0032] 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.

[0033] The preferred lower limit and preferred upper limit of the base polymer content in the adhesive composition of the present invention is 30% by mass. Having the base polymer content within this range further improves the adhesion strength of the adhesive layer formed using the adhesive composition of the present invention to the fluororesin. A more preferred lower limit for the base polymer 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.

[0034] The adhesive composition of the present invention contains a tackifying resin. The tackifying resin described above includes a tackifying resin (T1-1) having at least one constituent unit (A) selected from the group consisting of constituent units (A-1), (A-1'), (A-2), (A-2'), (A-3), (A-3'), (A-4), and (A-4') represented by the above formula. By including the tackifying resin (T1-1) in the adhesive composition of the present invention, the adhesive layer formed using the adhesive composition of the present invention can exhibit high adhesive strength, particularly high adhesive strength to substrates with low polarity (for example, fluororesins, etc.). In particular, the interaction with the adherend can be greatly improved, and the adhesive strength to the adherend can be further enhanced, so it is preferable that the above-mentioned structural unit (A) is at least one selected from the group consisting of structural unit (A-1), structural unit (A-1'), structural unit (A-2), structural unit (A-2'), structural unit (A-3), and structural unit (A-3'), and it is more preferable that it is at least one selected from the group consisting of structural unit (A-1) and structural unit (A-1'). By the above-mentioned structural unit (A) being at least one selected from the group consisting of structural unit (A-1) and structural unit (A-1'), the interaction with the adherend can be further greatly improved. Furthermore, since monomers containing bio-derived materials, which will be described later, can be easily used as monomers constituting the above-mentioned structural unit (A-1) and structural unit (A-1'), it is preferable from the viewpoint of saving petroleum resources. Furthermore, the tackifying resin (T1-1) having appropriate polarity improves its compatibility with the (meth)acrylic copolymer.

[0035] The tackifying resin (T1-1) may have the above-mentioned structural unit (A) in the side chain, or in the main chain skeleton or at the ends of the main chain skeleton. In particular, it is preferable that the tackifying resin (T1-1) has the above-mentioned structural unit (A) in the main chain skeleton or at the ends of the main chain skeleton, as this allows it to have suitable physical properties required as a tackifying resin.

[0036] In the above constituent unit (A), R 1~R 7 represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group, respectively. Examples of the aliphatic hydrocarbon group include linear, branched, or cyclic alkyl groups having 1 to 20 carbon atoms. Examples of the aromatic hydrocarbon group include substituted or unsubstituted aryl groups having 1 to 20 carbon atoms. Specific examples of the polar functional group include an amino group, a carboxy group, a carbonyl group, an alkoxy group, a hydroxyl group, a nitrile group, a nitro group, etc. R 1 As R, a polar functional group other than a hydroxyl group can be used. R 2 As R, a polar functional group other than a carboxy group can be used. R 3 As R, a polar functional group other than the group represented by OR 4 can be used. R 5 As R, a polar functional group other than the group represented by NR 6 R 7 can be used. Examples of the aliphatic hydrocarbon group having a polar functional group include a group in which one or more hydrogens in the aliphatic hydrocarbon group are substituted with the polar functional group. Examples of the aromatic hydrocarbon group having a polar functional group include a group in which one or more hydrogens in the aromatic hydrocarbon group are substituted with the polar functional group.

[0037] In the above tackifier resin (T1-1), the plurality of R 1 contained in one constitutional unit (A-1) may be the same or different from each other. Also, the plurality of R 1 contained in different constitutional units (A-1) may be the same or different from each other as well. Similarly, the plurality of R 1 contained in one constitutional unit (A-1’) may be the same or different from each other. Also, the plurality of R 1 contained in different constitutional units (A-1’) may be the same or different from each other.

[0038] Similarly, multiple R units contained within a single constituent unit (A-2) 2 These may be the same or different. Also, multiple Rs contained in different constituent units (A-2) 2 These may be the same or different. Similarly, multiple Rs contained within a single constituent unit (A-2') 2 These may be the same or different. Also, multiple Rs contained in different constituent units (A-2') 2 They may be the same or they may be different.

[0039] Similarly, multiple Rs contained within a single constituent unit (A-3) 3 These may be the same or different. Also, multiple Rs contained in different constituent units (A-3) 3 These may be the same or different. Similarly, multiple Rs contained within a single constituent unit (A-3') 3 These may be the same or different. Also, multiple Rs contained in different constituent units (A-3') 3 They may be the same or they may be different.

[0040] Similarly, multiple Rs contained within a single constituent unit (A-3) 4 These may be the same or different. Also, multiple Rs contained in different constituent units (A-3) 4 These may be the same or different. Similarly, multiple Rs contained within a single constituent unit (A-3') 4 These may be the same or different. Also, multiple Rs contained in different constituent units (A-3') 4 They may be the same or they may be different.

[0041] Similarly, multiple Rs contained within a single constituent unit (A-4) 5These may be the same or different. Also, multiple Rs contained in different constituent units (A-4) 5 These may be the same or different. Similarly, multiple Rs contained within a single constituent unit (A-4') 5 These may be the same or different. Also, multiple Rs contained in different constituent units (A-4') 5 They may be the same or they may be different.

[0042] Similarly, multiple Rs contained within a single constituent unit (A-4) 6 and R 7 These may be the same or different. Also, multiple Rs contained in different constituent units (A-4) 6 and R 7 These may be the same or different. Similarly, multiple Rs contained within a single constituent unit (A-4') 6 and R 7 These may be the same or different. Also, multiple Rs contained in different constituent units (A-4') 6 and R 7 They may be the same or they may be different.

[0043] In the above constituent unit (A), n and l are integers between 2 and 4, and n' and l' are integers between 2 and 5, but from the viewpoint of ease of obtaining raw materials, it is preferable that n, l, n', and l' are 2 or 3, and it is more preferable that n, l, n', and l' are 3, as this can further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention.

[0044] In the above constituent unit (A), m and k are integers between 1 and 4, and m' and k' are integers between 1 and 5, but from the viewpoint of ease of obtaining raw materials, it is preferable that m, k, m', and k' are 1, 2, or 3, and it is more preferable that m, k, m', and k' are 1, as this can further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention.

[0045] More specifically, the above-mentioned constituent units (A-1) and (A-1') include, for example, a constituent unit derived from dihydroxybenzene or its derivatives (when n and n' are 2), a constituent unit derived from trihydroxybenzene or its derivatives (when n and n' are 3), and so on. These constituent units may be used individually, or two or more may be used in combination.

[0046] Examples of the above-mentioned dihydroxybenzene or its derivatives include resorcinol, pyrocatechol, hydroquinone, dihydroxytoluene, dihydroxyxylene, dihydroxyphenylethylamine hydrochloride, dihydroxybenzoic acid, dihydroxyphenylacetic acid, dihydroxyhydrocinnamic acid, dihydroxyphenylpropionic acid, dihydroxyphenylalanine, dihydroxybenzaldehyde, dihydroxyacetophenone, diacetyldihydroxybenzene, dihydroxyphenyl-2-butanone, dihydroxyphenylmethyl acetate, benzyldihydroxyphenyl ketone, dihydroxybenzamide, dihydroxymethoxybenzene, dihydroxybenzyl alcohol, dihydroxyphenylethanol, dihydroxyphenyl glycol, dihydroxyphenylacetonitrile, and dihydroxynitrobenzene. Among these, pyrocatechol is preferred because it has low steric hindrance and readily interacts with the adherend. The above-mentioned dihydroxybenzene or its derivatives may be used alone or in combination of two or more types.

[0047] Examples of the above-mentioned trihydroxybenzene or its derivatives include pyrogallol, 1,2,4-trihydroxybenzene, phloroglucinol, trihydroxytoluene, trihydroxydiphenylmethane, 6-hydroxy-L-dopa, gallic acid, methyl gallate, butyl gallate, isobutyl gallate, isoamyl gallate, hexadecyl gallate, stearyl gallate, trihydroxyacetophenone, trihydroxyphenylethanone, trihydroxyphenylbutanone, trihydroxybenzaldehyde, trihydroxybenzamide, and trihydroxynitrobenzene. Among these, pyrogallol is preferred because it has low steric hindrance and readily interacts with the adherend. The above-mentioned trihydroxybenzene or its derivatives may be used alone or in combination of two or more types.

[0048] More specifically, the above-mentioned constituent units (A-2) and (A-2') include constituent units derived from benzoic acid, salicylic acid, dihydroxybenzoic acid, gallic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, 2-ethylbenzoic acid, 3-ethylbenzoic acid, 4-ethylbenzoic acid, 4-tert-butylbenzoic acid, 2-vinylbenzoic acid, 3-vinylbenzoic acid, 4-vinylbenzoic acid, 4,4'-stilbendicarboxylic acid, and their derivatives. Among these, the constituent unit derived from 4-vinylbenzoic acid is preferred because it has less steric hindrance and readily interacts with the adherend. These constituent units may be used individually, or two or more may be used in combination.

[0049] More specifically, the above-mentioned constituent units (A-3) and (A-3') include, for example, constituent units derived from dialkoxybenzene or its derivatives (when l and l' are 2), and constituent units derived from trialkoxybenzene or its derivatives (when l and l' are 3).

[0050] Examples of the above-mentioned dialkoxybenzene or its derivatives include 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, and 1,4-dimethoxybenzene. The above-mentioned dialkoxybenzene or its derivatives may be used alone or in combination of two or more types.

[0051] Examples of trialkoxybenzene or its derivatives include 1,2,3-trimethoxybenzene, 1,2,4-trimethoxybenzene, and 1,3,5-trimethoxybenzene. Among these, 1,2,3-trimethoxybenzene is preferred because it has low steric hindrance and readily interacts with the adherend. The above-mentioned trialkoxybenzene or its derivatives may be used alone or in combination of two or more types.

[0052] More specifically, the above-mentioned constituent units (A-4) and (A-4') include, for example, constituent units derived from aminobenzene or its derivatives (when k and k' are 1). Examples of the above-mentioned aminobenzene or its derivatives include aniline, methylaniline, ethylaniline, dimethylaniline, and diethylaniline. The above-mentioned aminobenzene or its derivatives may be used alone or in combination of two or more types.

[0053] The above-mentioned component (A) may consist solely of petroleum-derived materials, but it is preferable that it includes bio-derived materials. The depletion of petroleum resources and the emission of carbon dioxide from the combustion of petroleum-derived products are serious concerns. Therefore, attempts are being made to conserve petroleum resources by using bio-derived materials instead of petroleum-derived materials. It is preferable from the standpoint of conserving petroleum resources if the above-mentioned component (A) includes bio-derived materials. Furthermore, if the above-mentioned component (A) includes bio-derived materials, since bio-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, it is thought that burning them will not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the standpoint of reducing carbon dioxide emissions. Examples of monomers constituting the above-mentioned constituent unit (A), which includes bio-derived materials, include resorcinol, dihydroxyphenylethylamine hydrochloride, dihydroxyhydrocinnamic acid, dihydroxyphenylalanine, dihydroxybenzaldehyde, dihydroxybenzyl alcohol, pyrogallol, 1,2,4-trihydroxybenzene, phloroglucinol, 6-hydroxy-L-dopa, gallic acid, methyl gallate, butyl gallate, isobutyl gallate, isoamyl gallate, hexadecyl gallate, stearyl gallate, trihydroxyacetophenone, trihydroxybenzaldehyde, trihydroxybenzamide, trihydroxynitrobenzene, and the like.

[0054] The preferred lower limit of the content (on a molar basis) of the above-mentioned constituent unit (A) in the tackifying resin (T1-1) is 1 mol%, and the preferred upper limit is 60 mol%. By having a content of 1 mol% or more of the above-mentioned constituent unit (A), the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention can be further improved. By having a content of 60 mol% or less of the above-mentioned constituent unit (A), the above-mentioned tackifying resin (T1-1) will have the preferred physical properties required as a tackifying resin. A more preferred lower limit of the content of the above-mentioned constituent unit (A) is 5 mol%, a more preferred upper limit is 50 mol%, an even more preferred lower limit is 10 mol%, and an even more preferred upper limit is 30 mol%. Furthermore, the preferred lower limit (by mass) of the content ratio (by mass) of the above-mentioned constituent unit (A) in the tackifying resin (T1-1) is 0.9% by mass, and the preferred upper limit is 60% by mass. By having a content ratio of 0.9% by mass or more of the above-mentioned constituent unit (A), the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention can be further improved. By having a content ratio of 60% by mass or less of the above-mentioned constituent unit (A), the above-mentioned tackifying resin (T1-1) will have the preferred physical properties required as a tackifying resin. A more preferred lower limit for the content ratio of the above-mentioned constituent unit (A) is 5% by mass, a more preferred upper limit is 50% by mass, an even more preferred lower limit is 10% by mass, and an even more preferred upper limit is 30% by mass.

[0055] Preferably, the tackifying resin (T1-1) further has a constituent unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers. By having the above constituent unit (B) in the tackifying resin (T1-1), the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention can be further improved. Furthermore, from the viewpoint of improving compatibility with the base polymer, the tackifying resin (T1-1) is preferably composed of structural units derived from terpene monomers. Since the structural units derived from terpene monomers have an aliphatic hydrocarbon group having an unsaturated double bond, the compatibility between the tackifying resin (T1-1) and the base polymer is improved when the tackifying resin (T1-1) has structural units derived from terpene monomers, and it is possible to suppress a decrease in the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention due to deterioration of compatibility.

[0056] Examples of the above-mentioned terpene monomers include α-pinene, β-pinene, limonene, dipentene, δ-3-carene, dimethyloctatriene, allocimene, myrcene, ocimene, linalool, and cosmene. Among these, α-pinene, β-pinene, or limonene are preferred because they can further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention. As the vinyl monomers mentioned above, vinyl monomers that do not have a structure containing two or more aromatic rings in one molecule (for example, naphthalene structure, anthracene structure, biphenyl structure, anthraquinone structure, benzophenone structure, etc.) are preferred from the viewpoint of improving the compatibility between the tackifying resin (T1-1) and the base polymer. Examples of vinyl monomers that do not have a structure containing two or more aromatic rings in a single molecule include ethylene, propylene, butylene, hexene, vinyl acetate, vinyl chloride, styrene, α-methylstyrene, coumarone, indene, vinyltoluene, divinylbenzene, divinyltoluene, and 2-phenyl-2-butene. Among these, styrene is preferred because it can further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention. The above monomer (b) may be used alone or in combination of two or more types.

[0057] The above-mentioned component unit (B) may consist solely of petroleum-derived materials, but it is preferable that it includes bio-derived materials. The depletion of petroleum resources and the emission of carbon dioxide from the combustion of petroleum-derived products are serious concerns. Therefore, attempts are being made to conserve petroleum resources by using bio-derived materials instead of petroleum-derived materials. It is preferable from the standpoint of conserving petroleum resources if the above-mentioned component unit (B) includes bio-derived materials. Furthermore, if the above-mentioned component unit (B) includes bio-derived materials, since bio-derived materials are originally produced by absorbing carbon dioxide from the atmosphere, it is thought that burning them will not increase the total amount of carbon dioxide in the atmosphere, which is also preferable from the standpoint of reducing carbon dioxide emissions. Examples of monomers (b) that constitute the above-mentioned constituent unit (B) containing bio-derived materials include terpene monomers, ethylene, propylene, hexene, and the like.

[0058] The preferred lower limit for the content of the constituent unit (B) in the tackifying resin (T1-1) is 40 mol%, and the preferred upper limit is 99 mol%. By having a content of 40 mol% or more of the constituent unit (B), the tackifying resin (T1-1) can have the desirable physical properties required as a tackifying resin. By having a content of 99 mol% or less of the constituent unit (B), the content of the constituent unit (A) can be sufficiently secured, thereby further improving the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention, and in particular, further improving the adhesive strength even to adherends with low polarity. The more preferred lower limit for the content of the constituent unit (B) is 50 mol%, and the more preferred upper limit is 90 mol%.

[0059] The tackifying resin (T1-1) is preferably a copolymer having a structure represented by the following formula. In particular, when the above constituent unit (A) is present in or at the end of the main chain skeleton, it is preferable that the copolymer has a structure represented by the following formula. Copolymers having such a structure are obtained by a cationic polymerization method as described later, and can further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention, and in particular can further improve the adhesive strength even to adherends with low polarity.

[0060] [ka]

[0061] In the formula, A represents a constituent unit (A), B represents a constituent unit (B), and s and t each represent an integer greater than or equal to 1. * represents a connection.

[0062] The tackifying resin (T1-1) is preferably a copolymer having the above-mentioned structural unit (A) and the above-mentioned structural unit (B), and may further have other structural units. When the tackifying resin (T1-1) is a copolymer having the above-mentioned structural unit (A) and the above-mentioned structural unit (B), the above-mentioned structural unit (A) and the above-mentioned structural unit (B) may be copolymerized randomly, or they may be copolymerized in a regular or periodic manner, for example, when each forms a block segment and the block segments are bonded to each other.

[0063] The tackifying resin (T1-1) preferably has an aliphatic hydrocarbon group having an unsaturated double bond. The tackifying resin (T1-1) may have the aliphatic hydrocarbon group having an unsaturated double bond in the constituent unit (A) or the constituent unit (B), or in other constituent units. In particular, from the viewpoint of ease of synthesis and from the viewpoint of improving the compatibility between the tackifying resin (T1-1) and the base polymer, it is preferable that the aliphatic hydrocarbon group having an unsaturated double bond be in the constituent unit (B) or other constituent units. The constituent unit (B) or other constituent units having such aliphatic hydrocarbon group having an unsaturated double bond are not particularly limited, but it is preferable that the constituent unit (B) is derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers. That is, the tackifying resin (T1-1) preferably has the aliphatic hydrocarbon group having an unsaturated double bond in a constituent unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers. In particular, it is preferable that the structural unit derived from the terpene monomer has an aliphatic hydrocarbon group having the above-mentioned unsaturated double bond, as this can further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention.

[0064] Other constituent units mentioned above include, for example, constituent units derived from other phenolic monomers not included in constituent unit (A), and constituent units derived from maleic anhydride. Other phenolic monomers mentioned above include, for example, phenol, cresol, xylenol, propylphenol, norylphenol, methoxyphenol, bromophenol, bisphenol A, bisphenol F, bisphenol S, and dihydroxynaphthalene. The other phenolic monomers mentioned above may be used individually or in combination of two or more.

[0065] The preferred lower limit of the weight-average molecular weight (Mw) of the above tackifying resin (T1-1) is 400, and the preferred upper limit is 10,000. When the weight-average molecular weight (Mw) of the above tackifying resin (T1-1) is within this range, the above tackifying resin (T1-1) will have the desirable physical properties required as a tackifying resin. A more preferred lower limit of the weight-average molecular weight (Mw) of the above tackifying resin (T1-1) is 500, a more preferred upper limit is 5000, an even more preferred lower limit is 600, and an even more preferred upper limit is 3000. Methods for adjusting the weight-average molecular weight (Mw) to the above range include, for example, adjusting the composition, polymerization method, and polymerization conditions of the tackifying resin (T1-1).

[0066] The preferred lower limit of the Young's modulus of the tackifying resin (T1-1) at 25°C is 10 MPa. A Young's modulus of 10 MPa or higher at 25°C for the tackifying resin (T1-1) provides appropriate hardness and desirable physical properties required for a tackifying resin. A more preferred lower limit for the Young's modulus of the tackifying resin (T1-1) at 25°C is 50 MPa, and an even more preferred lower limit is 70 MPa. Furthermore, from the viewpoint of preventing the adhesive layer formed using the adhesive composition of the present invention from becoming too hard and reducing its adhesive strength, a preferred upper limit for the Young's modulus of the tackifying resin (T1-1) at 25°C is 10,000 MPa, and a more preferred upper limit is 5,000 MPa. The Young's modulus of the tackifying resin (T1-1) at 25°C can be measured by performing a tensile test using a tensile testing machine (e.g., ORIENTEC's "Tensilon") under the conditions of a tensile speed of 200 mm / min, a grip distance of 15 mm, and a temperature of 25°C. A sample for this measurement can be obtained, for example, by filling a mold measuring 10 × 50 mm with the tackifying resin (T1-1) and melting it at a temperature 100°C higher than the glass transition temperature to produce a test piece with a thickness of 1 mm.

[0067] Methods for adjusting the Young's modulus of the tackifying resin (T1-1) at 25°C to within the above range include, for example, adjusting the molecular weight or weight-average molecular weight (Mw) of the tackifying resin (T1-1), the composition and content ratio of the constituent units (A) and (B) in the tackifying resin (T1-1), etc.

[0068] The preferred lower limit for the glass transition temperature of the tackifying resin (T1-1) is 0°C, and the preferred upper limit is 200°C. Because the glass transition temperature of the tackifying resin (T1-1) is within this range, the Young's modulus of the tackifying resin (T1-1) at 25°C is easily adjusted to within this range, thus the tackifying resin (T1-1) possesses the desirable physical properties required for a tackifying resin. A more preferred lower limit for the glass transition temperature of the tackifying resin (T1-1) is 10°C, and a more preferred upper limit is 150°C.

[0069] The preferred lower limit of the iodine value of the tackifying resin (T1-1) is 2 g / 100 g, and the preferred upper limit is 180 g / 100 g. Having an iodine value of 2 g / 100 g or higher makes it easier to suppress the decrease in adhesive strength of the adhesive layer formed using the adhesive composition of the present invention, which is caused by poor compatibility between the tackifying resin (T1-1) and the base polymer (P1). Having an iodine value of 180 g / 100 g or lower makes it possible to further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention, and in particular, to further improve adhesive strength even to low-polarity adherends. A more preferred lower limit of the iodine value of the tackifying resin (T1-1) is 70 g / 100 g, and a more preferred upper limit is 170 g / 100 g. The iodine value is an indicator of the amount of unsaturated double bonds (C=C bond amount), and refers to the value measured in accordance with the method described in "JIS K 0070:1992".

[0070] The preferred lower limit for the content of bio-derived carbon (carbon atoms) in the carbon (carbon atoms) of the above-mentioned tackifying resin (T1-1) is 10%. A bio-derived carbon content of 10% or more is an indicator that a product is "bio-based". The above tackifying resin (T1-1) is preferable if it contains 10% or more bio-derived carbon, from the viewpoint of conserving petroleum resources and reducing carbon dioxide emissions. A more preferable lower limit for the bio-derived carbon content of the above tackifying resin (T1-1) is 30%, an even more preferable lower limit is 60%, an even more preferable lower limit is 70%, and a particularly preferable lower limit is 90%. There is no particular preferred upper limit for the bio-derived carbon content of the above tackifying resin (T1-1), and it may be 100%. Furthermore, while bio-derived carbon contains a certain percentage of the radioactive isotope (C-14), petroleum-derived carbon contains almost no C-14. Therefore, the percentage of bio-derived carbon in the above-mentioned tackifying resin (T1-1) can be calculated by measuring the concentration of C-14 contained in the compound. Specifically, this can be measured in accordance with ASTM D6866-22, a standard widely used in the bioplastics industry.

[0071] The tackifying resin (T1-1) described above also includes hydrogenated compounds of the compounds mentioned above. A hydrogenated compound is a compound in which the carbon-carbon double bonds present in the tackifying resin (T1-1) described above are saturated by hydrogenation, at least partially. That is, the adhesive composition of the present invention may contain a hydrogenated compound in which some of the carbon-carbon double bonds in the tackifying resin (T1-1) are hydrogenated, or it may contain a hydrogenated compound in which all of the carbon-carbon double bonds in the tackifying resin (T1-1) are hydrogenated. Even such a hydrogenated compound can be suitably used as a tackifying resin to be incorporated into the adhesive composition of the present invention, and can improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention, and in particular can improve the adhesive strength even to adherends with low polarity.

[0072] The method for producing the above-mentioned tackifying resin (T1-1) is not particularly limited, but when the above-mentioned constituent unit (A) is present in or at the end of the main chain skeleton, the following method is preferred, for example. In other words, a method of copolymerizing monomer (a) constituting the above-mentioned structural unit (A) with at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers constituting the above-mentioned structural unit (B) (hereinafter also referred to as "production method [I]") is preferred.

[0073] The monomer (a) is preferably at least one selected from the group consisting of monomer (a-1), monomer (a-2), monomer (a-3), and monomer (a-4), which are represented by the following formula.

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] In formulas (a-1) to (a-4), R 1 ~R 7 Each of the following represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group. n'' represents an integer between 2 and 5, preferably 2 or 3, and more preferably 3. m'' represents an integer between 1 and 5. l'' represents an integer between 2 and 5. k'' represents an integer between 1 and 5.

[0079] In the method for producing the tackifying resin (T1-1) described above [I], it is preferable to copolymerize monomer (a) and monomer (b) by cationic polymerization. By using the cationic polymerization described above, monomer (a) and monomer (b) can be copolymerized without prior chemical modification to protect the functional groups of monomer (a), such as phenolic hydroxyl groups, carboxyl groups, alkoxy groups, and amino groups, and subsequent deprotection is also unnecessary. Therefore, monomer (a) and monomer (b) can be copolymerized in a simpler one-step reaction process, leading to a reduction in impurities and an improvement in yield.

[0080] A preferred method for copolymerizing monomer (a) and monomer (b) by cationic polymerization is to react monomer (a) and monomer (b) in the presence of a Lewis acid. This method is thought to generate cations of monomer (b), leading to cationic polymerization between monomers (b) and a Fridel-Crafts alkylation reaction between monomer (a) and monomer (b). Repeated reactions of this nature allow for the production of a copolymer having constituent units (A) derived from monomer (a) and constituent units (B) derived from monomer (b). The Lewis acid mentioned above is not particularly limited, and conventionally known Lewis acids can be used, such as aluminum chloride (AlCl3), diethylaluminum chloride (Et2AlCl2), tin(IV) chloride (SnCl4), titanium(IV) chloride (TiCl4), boron trichloride (BCl3), and boron trifluoride ether complex (BF3·EtO). Among these, aluminum chloride (AlCl3) is preferred because it yields a higher yield of copolymer.

[0081] More specifically, for example, if pyrogallol is used as monomer (a) and α-pinene is used as monomer (b), and these are reacted in the presence of aluminum chloride (AlCl3), which is a Lewis acid, the reaction shown in the following scheme is expected to proceed. Specifically, a cation of monomer (b), α-pinene, is generated, and cationic polymerization of α-pinenes proceeds (upper part of the scheme below), while a Fridel-Crafts alkylation reaction proceeds between monomer (a), pyrogallol, and monomer (b), α-pinene (middle part of the scheme below). By repeatedly performing such reactions, a copolymer having structural units derived from pyrogallol and structural units derived from α-pinene can be obtained (lower part of the scheme below). Such a copolymer will have structural units derived from pyrogallol in the main chain skeleton or at the ends of the main chain skeleton.

[0082] [ka]

[0083] In the expression, s and t each represent an integer greater than or equal to 1. * represents a concatenation.

[0084] As for the method of producing the above-mentioned tackifying resin (T1-1), if the above-mentioned structural unit (A) is present in the side chain, for example, the following method is preferred. In other words, a method of copolymerizing a monomer (a') obtained by introducing an unsaturated double bond to monomer (a) constituting the above-mentioned structural unit (A), with at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers constituting the above-mentioned structural unit (B) (hereinafter also referred to as "production method [II]") is preferred.

[0085] Examples of the above monomer (a') include 2-vinylbenzoic acid, 3-vinylbenzoic acid, 4-vinylbenzoic acid, and 4,4'-stilbendicarboxylic acid. Among these, 4-vinylbenzoic acid is preferred because it has less steric hindrance and readily interacts with the adherend. The above monomer (a') may be used alone or in combination of two or more types.

[0086] In the above method for producing the tackifying resin (T1-1) [II], it is preferable to copolymerize the monomer (a') and the monomer (b) by cationic polymerization, similar to the method for producing the tackifying resin (T1-1) [I]. A preferred method for copolymerizing monomer (a') and monomer (b) by cationic polymerization is to react monomer (a') and monomer (b) in the presence of a Lewis acid as described above. By such a method, cationic polymerization proceeds between the unsaturated double bond in monomer (a') and the unsaturated double bond in monomer (b), and a copolymer having constituent units (A) derived from monomer (a') and constituent units (B) derived from monomer (b) can be obtained.

[0087] The above-mentioned tackifying resin (T1-1) has a preferred lower limit of softening temperature of 50°C and a preferred upper limit of 90°C. A softening temperature of 50°C or higher for the above-mentioned tackifying resin (T1-1) prevents the adhesive layer formed using the adhesive composition of the present invention from becoming too soft and reducing its adhesive strength. A softening temperature of 90°C or lower for the above-mentioned tackifying resin (T1-1) improves the wettability of the interface of the adhesive layer formed using the adhesive composition of the present invention, thereby preventing interfacial delamination. Furthermore, the glass transition temperature (Tg) of the above-mentioned (meth)acrylic copolymer is further reduced. As a result, the flexibility of the adhesive layer formed using the adhesive composition of the present invention is further improved, leading to improved adhesion of the adhesive layer to fluororesin and improved adhesion to the substrate described later. A more preferred lower limit of softening temperature for the above-mentioned tackifying resin (T1-1) is 55°C, and a more preferred upper limit is 85°C. In this specification, the softening temperature refers to the softening temperature measured by a method compliant with JIS K 2207 (ring-ball method).

[0088] The tackifying resin (T1-1) described above can improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention, even in a small amount compared to conventional tackifying resins. The preferred lower limit of the content of the tackifying resin (T1-1) per 100 parts by mass of the base polymer is 5 parts by mass, and the preferred upper limit is 30 parts by mass. By having a content of 5 parts by mass or more of the tackifying resin (T1-1), the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention can be further improved, and in particular, the adhesive strength to low-polarity adherends (e.g., fluororesins, etc.) can be further improved. By having a content of 30 parts by mass or less of the tackifying resin (T1-1), a decrease in adhesive strength caused by the adhesive layer formed using the adhesive composition of the present invention becoming too hard can be suppressed. The more preferred lower limit of the content of the tackifying resin (T1-1) is 10 parts by mass, and the more preferred upper limit is 20 parts by mass.

[0089] The tackifying resin described above preferably further comprises at least one tackifying resin (T1-2) selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins. By including the tackifying resin (T1-2), the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention can be further improved. In particular, the tackifying resin (T1-2) is more preferably composed of at least one tackifying resin selected from the group consisting of rosin ester resins and terpene resins because it can further improve the adhesive strength to low-polarity adherends (e.g., fluororesins, etc.), and the tackifying resin (T1-2) is even more preferably composed of a rosin ester resin because it can further improve the adhesive strength to low-polarity adherends (e.g., fluororesins, etc.).

[0090] The preferred lower limit of the softening temperature of the tackifying resin (T1-2) is 50°C, and the preferred upper limit is 200°C. A softening temperature of 50°C or higher for the tackifying resin (T1-2) prevents the adhesive layer formed using the adhesive composition of the present invention from becoming too soft and reducing its adhesive strength. A softening temperature of 200°C or lower for the tackifying resin (T1-2) improves the wettability of the interface of the adhesive layer formed using the adhesive composition of the present invention, preventing interfacial delamination. Furthermore, the glass transition temperature (Tg) of the (meth)acrylic copolymer is further reduced. As a result, the flexibility of the adhesive layer formed using the adhesive composition of the present invention is further improved, thus improving the adhesive strength of the adhesive layer to the fluororesin. A more preferred lower limit of the softening temperature of the tackifying resin (T1-2) is 70°C, and a more preferred upper limit is 150°C.

[0091] The preferred lower limit of the hydroxyl value of the tackifying resin (T1-2) is 0 mgKOH / g, and the preferred upper limit is 200 mgKOH / g. Having the hydroxyl value of the tackifying resin (T1-2) within this range improves the wettability of the interface of the adhesive layer formed using the adhesive composition of the present invention, thereby suppressing interfacial delamination. A more preferred lower limit of the hydroxyl value of the tackifying resin (T1-2) 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).

[0092] 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).

[0093] 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).

[0094] 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. The constituent units derived from the phenol compound in the terpene phenol resin do not include the constituent units (A-1) and (A-1') mentioned above. 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).

[0095] 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).

[0096] The preferred lower limit for the content of the tackifying resin (T1-2) per 100 parts by mass of the base polymer is 5 parts by mass, and the preferred upper limit is 100 parts by mass. By having the content of the tackifying resin (T1-2) within this range, the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention can be further improved. A more preferred lower limit for the content of the tackifying resin (T1-2) is 10 parts by mass, a more preferred upper limit is 90 parts by mass, an even more preferred upper limit is 80 parts by mass, and an even more preferred upper limit is 70 parts by mass.

[0097] The preferred lower limit for the total content of the tackifying resin relative to 100 parts by mass of the base polymer is 10 parts by mass, and the preferred upper limit is 80 parts by mass. A total content of 10 parts by mass or more of the tackifying resin can further improve the adhesive strength of the adhesive layer formed using the adhesive composition of the present invention. A total content of 80 parts by mass or less of the tackifying resin can prevent the adhesive layer formed using the adhesive composition of the present invention from becoming too hard and reducing its adhesive strength. A more preferred lower limit for the total content of the tackifying resin is 15 parts by mass, a more preferred upper limit is 70 parts by mass, an even more preferred upper limit is 65 parts by mass, and an even more preferred upper limit is 60 parts by mass.

[0098] The adhesive composition of the present invention preferably further contains a crosslinking agent. By including the above-mentioned crosslinking agent, the (meth)acrylic copolymer can form a structure that is crosslinked by chemical crosslinking. As a result, the bulk cohesive force of the adhesive layer formed using the adhesive composition of the present invention is further improved, and the gel fraction of the adhesive layer, as described later, becomes larger, thus further improving the adhesive strength. Furthermore, from the viewpoint of storage stability and other factors, the above-mentioned crosslinking agent may be incorporated into the adhesive composition of the present invention immediately before forming the adhesive layer.

[0099] Examples of the above-mentioned crosslinking agents include isocyanate-based crosslinking agents, aziridine-based crosslinking agents, epoxy-based crosslinking agents, and metal chelate-type crosslinking agents. The above-mentioned crosslinking agents may be used alone or in combination of two or more types. When two or more crosslinking agents are used in combination, two or more of the same type of crosslinking agent may be used (for example, using two types of isocyanate-based crosslinking agents), or one or more different types of crosslinking agents may be used in combination (for example, using one or more isocyanate-based crosslinking agents and one or more epoxy-based crosslinking agents). In particular, it is preferable that the above-mentioned 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 formed using the adhesive composition of the present invention.

[0100] Examples of commercially available isocyanate-based crosslinking agents include Takenate 500 (manufactured by Mitsui Chemicals, Inc.) and Desmodulo L-75 (manufactured by Covestro Corporation).

[0101] The preferred lower limit for the content of the crosslinking agent per 100 parts by mass of the base polymer is 2 parts by mass, and the preferred upper limit is 15 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 formed using the adhesive composition of the present invention. A more preferred lower limit for the crosslinking agent content is 5 parts by mass, and a more preferred upper limit is 10 parts by mass.

[0102] The adhesive composition of the present invention preferably further contains a solvent. By including the above-mentioned solvent, the resulting adhesive composition can be applied more easily in thicker layers.

[0103] Examples of the solvents mentioned above include ethyl acetate and toluene.

[0104] The preferred lower limit of the solid content concentration of the adhesive composition of the present invention is 50% by mass, and the preferred upper limit is 80% by mass. Having the solid content concentration of the adhesive composition within this range makes it easier to apply thick coats of the resulting adhesive composition. A more preferred lower limit of the solid content concentration of the adhesive composition is 55% by mass, a more preferred upper limit is 75% by mass, and an even more preferred upper limit is 60% by mass. In this specification, the term "solid content" refers to components in the adhesive composition other than the solvent.

[0105] The adhesive composition of the present invention may further contain a coloring agent for the purpose of providing light-shielding properties. Examples of the coloring agent include carbon black, aniline black, and titanium dioxide. Among these, carbon black is preferred because it is relatively inexpensive and chemically stable.

[0106] The adhesive composition of the present invention 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.

[0107] The adhesive composition of the present invention, when measured using a B-type viscometer at 23°C and 10 rpm, has a preferred lower limit of 0.1 Pa·s and a preferred upper limit of 15 Pa·s. Having a viscosity within this range allows the resulting adhesive composition to be applied more easily in thick layers. A more preferred lower limit of 1 Pa·s, a more preferred upper limit of 10 Pa·s, and an even more preferred upper limit of 8 Pa·s is also present. Examples of the above-mentioned Type B viscometer include the LV-DV-E (manufactured by Brookfield). In the case where the adhesive composition of the present invention contains the above-mentioned crosslinking agent, the viscosity refers to the value measured for a composition containing all the components of the adhesive composition other than the crosslinking agent.

[0108] The adhesive composition of the present invention is suitably used for forming an adhesive layer in adhesive tapes. An adhesive tape having an adhesive layer (Y1) formed using the adhesive composition of the present invention is also one of the present inventions. Hereinafter, in the adhesive tape of the present invention, the adhesive composition of the present invention used to form the adhesive layer (Y1) will also be referred to as "adhesive composition (X1)", and the base polymer and tackifying resin contained in the adhesive composition (X1) will also be referred to as "base polymer (P1)" and "tackifying resin (T1)", respectively.

[0109] The preferred lower limit for the gel fraction of the adhesive layer (Y1) is 15% by mass, and the preferred upper limit is 60% by mass. When the gel fraction of the adhesive layer (Y1) is 15% by mass or more, the bulk strength of the adhesive layer (Y1) is increased, and the resulting adhesive tape has superior adhesion. When the gel fraction of the adhesive layer (Y1) is 60% by mass or less, the shear storage modulus of the adhesive layer (Y1) at 25°C is moderately reduced, the flexibility of the adhesive layer (Y1) is further improved, and the adhesion strength of the adhesive layer (Y1) to the fluororesin is further improved. The more preferred lower limit for the gel fraction of the adhesive layer (Y1) is 25% by mass, and the more preferred upper limit is 50% by mass. The gel fraction of the adhesive layer (Y1) can be measured by the following methods, etc. Specifically, a test specimen is prepared by cutting a substrate to which the adhesive layer (Y1) is attached, or the adhesive layer (Y1) alone, into a flat rectangular shape with a width of 50 mm and a length of 100 mm. The test specimen is immersed in an organic solvent at 23°C for 24 hours, then removed from the organic solvent and dried at 110°C for 1 hour. If the base polymer (P1) is a (meth)acrylic copolymer, ethyl acetate can be used as the organic solvent; if the base polymer (P1) is a styrene elastomer or silicone resin, toluene can be used. The mass of the dried test specimen is measured, and the gel fraction is calculated using the following formula (1). Note that the test specimen is not laminated with a release film to protect the adhesive layer (Y1). If the test specimen does not have a substrate, W0 is calculated as 0. Gel fraction (mass %) = 100 × (W2 - W0) / (W1 - W0) (1) (W0: Mass of the substrate, W1: Mass of the test specimen before immersion, W2: Mass of the test specimen after immersion and drying)

[0110] The gel fraction of the adhesive layer (Y1) can be adjusted to within the above range by, for example, adjusting the type and content ratio of monomers constituting the (meth)acrylic copolymer, the weight-average molecular weight (Mw) of the (meth)acrylic copolymer, the type and content of the crosslinking agent, etc.

[0111] The preferred lower limit for the thickness of the adhesive layer (Y1) is 100 μm, and the preferred upper limit is 1000 μm. The adhesive layer (Y1) having sufficient adhesive strength is within this range. A more preferred lower limit for the thickness of the adhesive layer (Y1) is 120 μm, an even more preferred lower limit is 150 μm, and a particularly preferred lower limit is 200 μm. A more preferred upper limit for the thickness of the adhesive layer (Y1) is 700 μm, an even more preferred upper limit is 600 μm, and a particularly preferred upper limit is 500 μm.

[0112] The adhesive tape of the present invention may further have a base material, from the viewpoint of ease of application and other factors. From the viewpoint of heat resistance and chemical resistance, the above-mentioned substrate preferably contains at least one selected from the group consisting of polyester resin, polyimide resin, polyether resin, polyolefin resin, polyurethane resin, metal, glass fiber, and carbon fiber.

[0113] Furthermore, the generation of air at the adhesive surface when the above-mentioned substrate is pressed against the adhesive layer can cause the adhesive layer to peel off easily. Therefore, it is preferable that the above-mentioned substrate includes at least one shape selected from the group consisting of nonwoven fabrics and woven fabrics, as this improves the anchoring strength of the substrate and improves air release properties by providing air passages to suppress air generation, thereby suppressing the peeling of the adhesive layer.

[0114] Examples of commercially available nonwoven fabric-like base materials include G2260-1S (manufactured by Toray International, Inc.). Examples of the woven base material mentioned above include glass cloth and carbon cloth. Among the glass cloths mentioned above, commercially available examples include KS2770 (manufactured by Nitto Boseki Co., Ltd.). Among the carbon cloths mentioned above, commercially available examples include C-540 (manufactured by Hagiwara Industries Co., Ltd.).

[0115] The preferred lower limit for the thickness of the above substrate is 50 μm, and the preferred upper limit is 1000 μm. Having the substrate thickness within this range further improves the interlayer strength of the resulting adhesive tape. A more preferred lower limit for the thickness of the above substrate is 100 μm, and an even more preferred lower limit is 120 μm. A more preferred upper limit for the thickness of the above substrate is 500 μm, and an even more preferred upper limit is 300 μm.

[0116] The adhesive tape of the present invention may have a base material, an adhesive layer (Y1) formed on one side of the base material using an adhesive composition (X1), and an adhesive layer (Y2) formed on the other side of the base material using an adhesive composition (X2). By having the adhesive layer (Y2) on the other side of the base material of the adhesive tape of the present invention, it becomes possible to bond a fluororesin and a dissimilar material at once.

[0117] The adhesive layer (Y2) described above is preferably the same as the adhesive layer (Y1) described above, from the viewpoint of having no front or back side and improving handling.

[0118] When using an adhesive layer (Y2) different from the adhesive layer (Y1), it is preferable that the adhesive layer (Y2) is a low-tack adhesive layer from the viewpoint of ease of bonding. Because the adhesive layer (Y2) is a low-tack adhesive layer, stickiness of the adhesive layer (Y2) can be suppressed, resulting in an adhesive tape with superior bonding ease.

[0119] The above adhesive composition (X2) preferably contains a base polymer (P2). The above-mentioned base polymer (P2) preferably contains at least one selected from the group consisting of (meth)acrylic copolymers, styrene elastomers, ethylene-vinyl acetate copolymers, chloroprene rubber, nitrile rubber, polyurethane resins, polyamide resins, polyolefin resins, polyester resins, epoxy resins, and silicone resins. In particular, from the viewpoint of suppressing stickiness and improving heat resistance, it is preferable to include at least one selected from the group consisting of (meth)acrylic copolymers and styrene elastomers.

[0120] Examples of the (meth)acrylic copolymer in the above-mentioned base polymer (P2) include the same as that used in the base polymer (P1) contained in the adhesive composition of the present invention (adhesive composition (X1)) described above.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] Examples of the styrene-based elastomers mentioned above include styrene-isoprene-styrene (SIS) block copolymer, styrene-butadiene-styrene (SBS) block copolymer, styrene-chloroprene-styrene 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 tape 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.

[0125] 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 higher, the adhesive strength of the adhesive layer (Y2) to the adherend is further improved, and the resulting adhesive tape has superior adhesive properties. A 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 (Y2), the preferred upper limit of the diblock 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).

[0126] A preferred upper limit for the content 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. When the styrene content is 20% by mass or less, the adhesive layer (Y2) does not become too hard, the adhesive strength to the adherend is further improved, and the resulting adhesive tape has superior adhesion. 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 (Y2), 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.

[0127] The preferred lower limit for the weight-average molecular weight (Mw) of the above styrene-based elastomer is 50,000, and the preferred upper limit is 600,000. A weight-average molecular weight (Mw) of 50,000 or more for the above styrene-based elastomer increases the bulk strength of the adhesive layer (Y2), resulting in a more adhesive tape with superior adhesion. A weight-average molecular weight (Mw) 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 (Mw) of the above styrene-based elastomer is 100,000, and a more preferred upper limit is 500,000.

[0128] Examples of commercially available silicone resins include KR-3700 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0129] Examples of commercially available ethylene-vinyl acetate copolymers include HM200 (manufactured by Cemedyne Co., Ltd.). Examples of commercially available chloroprene rubbers 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.). Examples of commercially available polyurethane resins include SHM107-PUR (manufactured by Seedam Corporation). Examples of commercially available polyamide resins include SHM301-PAD (manufactured by Seedam Corporation). Examples of commercially available polyolefin resins include PPET1200F (manufactured by Toagosei Co., Ltd.). Examples of commercially available polyester resins include PH-413 (manufactured by Nippon Matai Co., Ltd.). Examples of commercially available epoxy resins include 1500 (manufactured by Cemedyne Co., Ltd.).

[0130] The above adhesive composition (X2) preferably contains a tackifying resin (T2) from the viewpoint of further improving adhesive strength. The above tackifying resin (T2) preferably contains 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 (T1-2) described above.

[0131] 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 (meth)acrylic copolymer forms a crosslinked structure through chemical crosslinking, resulting in an adhesive tape with superior adhesion. Furthermore, from the viewpoint of storage stability and other factors, the crosslinking agent may be added to the adhesive composition (X2) immediately before forming the adhesive layer (Y2).

[0132] 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). Examples of the above-mentioned isocyanate-based crosslinking agent and epoxy-based crosslinking agent include those similar to those used in the adhesive composition of the present invention (adhesive composition (X1)) described above.

[0133] From the viewpoint of further improving adhesive strength, the above adhesive composition (X2) preferably contains a silane coupling agent. 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. The silane coupling agents described above may be used individually or in combination of two or more.

[0134] 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.

[0135] The preferred lower limit for the thickness of the adhesive layer (Y2) is 50 μm, and the preferred upper limit is 600 μm. By having the thickness of the adhesive layer (Y2) within this range, the adhesive layer (Y2) will have sufficient adhesive strength. A more preferred lower limit for the thickness of the adhesive layer (Y2) is 100 μm, and an even more preferred lower limit is 150 μm. A more preferred upper limit for the thickness of the adhesive layer (Y2) is 500 μm, an even more preferred upper limit is 450 μm, and a particularly preferred upper limit is 400 μm.

[0136] The adhesive tape of the present invention has a preferred lower limit of thickness of 200 μm and a preferred upper limit of thickness of 1200 μm. Having the thickness within this range results in an adhesive tape with superior bonding workability. A more preferred lower limit for the thickness of the adhesive tape of the present invention is 250 μm, an even more preferred lower limit is 300 μm, and a particularly preferred lower limit is 400 μm. A more preferred upper limit for the thickness of the adhesive tape of the present invention is 1000 μm, and an even more preferred upper limit is 800 μm.

[0137] The method for manufacturing the adhesive tape of the present invention is not particularly limited, and examples include the following methods. First, an adhesive composition (X1) is prepared by adding a solvent to a base polymer (P1) and a tackifying resin (T1), and optionally a crosslinking agent. The adhesive composition (X1) is then applied to the release surface of a release PET film, and the solvent in the composition is completely dried and removed to form an adhesive layer (Y1) and produce a laminated film. The resulting laminated film can be used as an adhesive tape having an adhesive layer (Y1) on a release PET film. Furthermore, by overlapping the prepared laminated film with the adhesive layer (Y1) facing the substrate and curing it for 48 hours in an environment of 40°C and 50%RH, an adhesive tape can be obtained that has an adhesive layer (Y1) on one side of the substrate. The step of applying the adhesive composition (X1) to the release treatment surface of the release PET film may be completed in one step, or it may be performed multiple times by applying it in layers on top of the applied adhesive composition (X1). By adjusting the number of application steps, the thickness of the adhesive layer (Y1) can be easily adjusted. Furthermore, another laminated film is prepared by applying an adhesive composition (X2) prepared by a similar method onto the release surface of a release PET film, and completely drying and removing the solvent in the composition to form an adhesive layer (Y2). The step of applying the adhesive composition (X2) onto the release surface of the release PET film may be performed once, or it may be performed multiple times by applying it in layers on top of the applied adhesive composition (X2). By adjusting the number of application steps, the thickness of the adhesive layer (Y2) can be easily adjusted. By overlapping the prepared laminated film with an adhesive layer (Y2) onto the substrate so that the side of the substrate without the adhesive layer (Y1) faces the adhesive layer (Y2), and curing it for 48 hours in an environment of 40°C and 50%RH, an adhesive tape can be obtained 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.

[0138] The applications of the adhesive tape of the present invention are not particularly limited, but because it has excellent adhesive strength to fluororesins such as polytetrafluoroethylene without pretreatment to the fluororesin, it is suitably used for joining fluororesins 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 is suitably used to protect adherends, and especially suitably used to protect adherends from chemical solutions. Furthermore, because the adhesive tape of the present invention can suppress peeling of the substrate and provide high-strength adhesion, it is more suitably used for lining the tank bodies of chemical solution tanks for semiconductors or chemical solutions tanks for the chemical industry.

[0139] A laminated sheet having a sheet containing fluororesin on the adhesive layer (Y1) side of the adhesive tape 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.

[0140] 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.

[0141] 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 tanks for semiconductors or chemical tanks for the chemical industry, or for piping used to transport chemical solutions, as a coating material for electronic equipment components, or as a building material. In particular, the laminated sheet of the present invention is suitably used for lining (surface treatment covering the inner surface of a can) of cans in chemical tanks for semiconductors or chemical tanks for the chemical industry.

[0142] A chemical tank in which the adhesive tape or laminated sheet of the present invention is attached to the inner surface of a can 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 tape of the present invention or the adhesive layer (Y1) in the laminated sheet of the present invention, thereby further suppressing peeling and lifting of the fluororesin caused by the chemical solution stored in the chemical tank to which the fluororesin is bonded.

[0143] A method for manufacturing a chemical tank for semiconductors or a chemical tank for the chemical industry, 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. Furthermore, a method for manufacturing a chemical tank, which includes the step of producing a laminated sheet of the present invention by pressing a sheet containing fluororesin onto the adhesive layer (Y1) of the adhesive tape of the present invention, and the step of attaching the adhesive layer (Y2) of the laminated sheet to the inner surface of the tank body of the chemical tank, is also one of the present inventions. [Effects of the Invention]

[0144] The present invention provides a (meth)acrylic adhesive composition that facilitates the bonding of fluororesins and allows for the creation of a thick, uniform coating film without placing a significant burden on the environment. Furthermore, the present invention provides an adhesive tape formed using the adhesive composition. Moreover, the present invention provides a laminated sheet having the adhesive tape, and a chemical tank to which the adhesive tape or the laminated sheet is attached. In addition, the present invention provides a method for manufacturing a chemical tank using the adhesive tape and the laminated sheet. [Brief explanation of the drawing]

[0145] [Figure 1] This diagram schematically illustrates a method for evaluating the holding power of adhesive tape. [Modes for carrying out the invention]

[0146] 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.

[0147] (Preparation of acrylic copolymers) (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 acrylic copolymer with a solid content of 25% by mass was obtained. The obtained acrylic copolymer solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (Waters, 2690 Separations Module), and GPC 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 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.

[0148] (Synthesis Examples 2-10) An acrylic copolymer was 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. The molecular weight of each acrylic copolymer was adjusted by controlling the reaction solid content by increasing or decreasing the amount of ethyl acetate.

[0149] The constituent monomers shown in Table 1 are as follows: BA: n-butyl acrylate nHexA: n-hexyl acrylate 2EHA:2-Ethylhexylacrylate nHepA:n-heptylacrylate HEA: 2-hydroxyethyl acrylate AAc: Acrylic acid

[0150] [Table 1]

[0151] (Preparation of tackifying resin (T1-1)) (Synthesis example A) 50 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) (n=2) 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 (T1-1). Regarding the obtained tackifying resin (T1-1) 1 ¹H-NMR measurements were performed to confirm that the tackifying resin (T1-1) is a copolymer having constituent units (A) derived from catechol (pyrocatechol) and constituent units (B) derived from α-pinene (a copolymer having constituent unit (A) in or at the ends of the main chain skeleton). The obtained tackifying resin (T1-1) 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.

[0152] (Measurement of the bio-derived carbon content of tackifying resin (T1-1)) The bio-derived carbon content of the obtained tackifying resin (T1-1) was measured according to ASTM D6866-22. The results are shown in Table 2.

[0153] (Measurement of the softening temperature of the tackifying resin (T1-1)) The softening temperature of the obtained tackifying resin (T1-1) was measured according to the method compliant with JIS K 2207 (ring-ball method). The results are shown in Table 2.

[0154] (Synthesis examples B-C and E) In the above-mentioned "(Preparation of Tackifying Resin (T1-1))", the tackifying resin (T1-1) was synthesized in the same manner as in "(Synthesis Example A)", except that the constituent unit monomers were changed as shown in Table 2, and measurements were performed. The results are shown in Table 2.

[0155] (Synthesis example D) (Preparation of tackifying resin (T1-1)) 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, while maintaining the toluene at 75°C, two parts by mass of aluminum chloride (AlCl3) were added. A solution of 70 parts by mass of 4-vinylbenzoic acid (m=1) 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 (T1-1). Regarding the obtained tackifying resin (T1-1) 1 ¹H-NMR measurements were performed to confirm that the tackifying resin (T1-1) is a copolymer having structural units (A) derived from 4-vinylbenzoic acid and structural units (B) derived from α-pinene (a copolymer having structural unit (A) in its side chains). The obtained tackifying resin (T1-1) 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.

[0156] (Measurement of the bio-derived carbon content of tackifying resin (T1-1)) The bio-derived carbon content of the obtained tackifying resin (T1-1) was measured according to ASTM D6866-22. The results are shown in Table 2.

[0157] (Measurement of the softening temperature of the tackifying resin (T1-1)) The softening temperature of the obtained tackifying resin (T1-1) was measured according to the method compliant with JIS K 2207 (ring-ball method). The results are shown in Table 2.

[0158] [Table 2]

[0159] (Example 1) (1) Preparation of adhesive compositions and adhesive tapes To 100 parts by mass of the solid content of the acrylic copolymer obtained in Synthesis Example 1 as the base polymer (P1), 20 parts by mass of the tackifying resin (T1-1) obtained in Synthesis Example B was added. Furthermore, 6 parts by mass of an isocyanate crosslinking agent (Desmodule L-75, manufactured by Covestro) and ethyl acetate (manufactured by Fuji Chemical Co., Ltd.) as a solvent were added, and the mixture was thoroughly stirred to obtain the adhesive composition (X1). The solid content concentration of the obtained adhesive composition (X1) is shown in Table 3. The obtained adhesive composition (X1) 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 obtain an adhesive tape having a 100 μm thick adhesive layer (Y1) on the release PET film.

[0160] (2) Measurement of viscosity of adhesive composition without crosslinking agent A composition containing all components of the obtained adhesive composition (X1) except for the isocyanate crosslinking agent was prepared, and the viscosity of this composition was measured using a B-type viscometer (BROOKFIELD, "LV-DV-E") at 23°C and 10 rpm. For the adhesive composition (X1) obtained in Example 7, the viscosity of the obtained adhesive composition (X1) itself was measured. The results are shown in Table 3.

[0161] (3) Measurement of the gel fraction of the adhesive layer Only the adhesive layer (Y1) was extracted from the obtained adhesive tape, cut into a flat rectangular shape measuring 50 mm wide x 100 mm long to prepare a test specimen, and its mass (W1 (g)) was measured. The obtained test specimen was immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The mass (W2 (g)) of the dried test specimen was measured, and the gel fraction of the adhesive layer (Y1) was calculated from formula (1) above, with W0 set to 0. The results are shown in Table 3.

[0162] (Examples 2-30, Comparative Examples 1-5) In Example 1 described above, in "(1) Preparation of adhesive composition and adhesive tape," an adhesive tape was prepared and measured in the same manner as in Example 1, except that the composition of the adhesive composition (X1) and the thickness of the adhesive layer (Y1) were as shown in Tables 3 to 6. The results are shown in Tables 3 to 6.

[0163] (Examples 31-33) (1) Preparation of adhesive compositions and adhesive tapes In Example 1 described above, in "(1) Preparation of adhesive composition and adhesive tape," the adhesive composition (X1) was obtained in the same manner as in Example 1, except that the composition of the adhesive composition (X1) was as shown in Table 5. The solid content concentration of the obtained adhesive composition (X1) is shown in Table 5. The obtained adhesive composition (X1) 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 obtain a laminated film having a 100 μm thick adhesive layer (Y1) on the release PET film. The substrates shown in Table 5 were prepared, and the prepared laminated film was placed on top of the substrate so that the adhesive layer (Y1) faced the substrate. The film was then cured by heating at 40°C for 48 hours. This resulted in an adhesive tape having a substrate and an adhesive layer (Y1) on one side of the substrate.

[0164] (2) Measurement of viscosity of adhesive composition without crosslinking agent A composition containing all components of the obtained adhesive composition (X1) except for the isocyanate crosslinking agent was prepared, and the viscosity of this composition was measured using a B-type viscometer (BROOKFIELD, "LV-DV-E") at 23°C and 10 rpm. The results are shown in Table 5.

[0165] (3) Measurement of the gel fraction of the adhesive layer The obtained adhesive tape was cut into a flat rectangular shape measuring 50 mm in width and 100 mm in length to prepare test specimens, and their mass (W1 (g)) was measured. The obtained test specimens were immersed in ethyl acetate at 23°C for 24 hours, then removed from the ethyl acetate and dried at 110°C for 1 hour. The mass (W2 (g)) of the dried test specimens was measured, and using the previously measured mass of the substrate (W0 (g)), the gel fraction of the adhesive layer (Y1) was calculated from formula (1) above. The results are shown in Table 5.

[0166] <Rating> The obtained adhesive compositions and adhesive tapes were evaluated using the following methods. The results are shown in Tables 3 to 6.

[0167] (Applicability of adhesive compositions) (1) Maximum coating thickness The obtained adhesive composition (X1) was applied to the release surface of a 75 μm thick release PET film (Toyo Cloth Co., Ltd., "SP3000") to a thickness of 30 mil using an applicator, and dried at 100°C for 5 minutes to form an adhesive layer (Y1) on the release PET film, thereby creating a laminated film. A 50 μm thick PET film (Futamura Chemical Co., Ltd., "FE2002") was prepared as the substrate, and the prepared laminated film was overlapped so that the adhesive layer (Y1) faced the substrate, and then cured by heating at 40°C for 48 hours. The thickness of the adhesive layer (Y1) after curing was taken as the maximum coating thickness and evaluated according to the following criteria. ◎: When the maximum coating thickness is 250 μm or more ○: When the maximum coating thickness is 150 μm or more and less than 250 μm. △: When the maximum coating thickness is 100 μm or more but less than 150 μm. ×: If the maximum coating thickness is less than 100 μm

[0168] (2) Appearance of the coating The obtained adhesive composition (X1) was applied to the release surface of a 75 μm thick release PET film (Toyo Cloth Co., Ltd., "SP3000") to obtain a laminated film having a 300 μm thick coating on the release PET film. The appearance of the obtained coating was visually inspected and evaluated according to the following criteria. ○: When there are no streaks on the surface or repulsion between the coating and the release PET film, and a uniform coating film is obtained. △: If at least one of the following is observed: surface streaks or repellency between the release PET film and the surface. ×: If a large number of surface streaks or repellencies between the release PET film and the surface are observed.

[0169] (Adhesion of the adhesive layer to the fluororesin) After cutting the obtained adhesive tape to a size of 25 mm wide x 100 mm long, the adhesive layer (Y1) side was pressed onto a 2 mm thick polytetrafluoroethylene sheet (Yodogawa Hutech Co., Ltd., "Yodoflon") by using a 2 kg rubber roller to roll it back and forth once at a speed of 300 mm / min. Test specimens were then prepared by curing them for 20 minutes at 23°C and 50% RH. A 180° peel test was performed on the obtained test specimens using a tensile testing machine (ORIENTEC Co., Ltd., "Tensilon") in accordance with JIS Z 0237, at 23°C and a peeling speed of 300 mm / min. The 180° peel force of the adhesive layer (Y1) to PTFE at 23°C was measured by peeling the adhesive layer (Y1) from the polytetrafluoroethylene film. The adhesion of the adhesive layer to fluororesin was evaluated according to the following criteria. ◎: When the 180° peeling force is 4N / 25mm or more ○: When the 180° peeling force is 3N / 25mm or more and less than 4N / 25mm. △: When the 180° peeling force is 1N / 25mm or more and less than 3N / 25mm ×: If the 180° peeling force is less than 1N / 25mm

[0170] (retention) After peeling the release PET film from the obtained adhesive tape, it was cut into 25mm wide strips and bonded to a SUS plate (SUS304 plate washed with ethanol and then wiped dry) by running a 2kg rubber roller back and forth at a speed of 300mm / min once. Next, cuts were made in the adhesive tape so that the bonding area was 25mm x 25mm, and the test sample was prepared by letting it stand at 23°C for 20 minutes. The prepared test sample was placed in an 80°C oven and heated for another 20 minutes, and then a 500g weight was suspended under 80°C and 50%RH conditions as shown in Figure 1 to apply a load in the shear direction. The amount of displacement (movement) (mm) from the cut position one hour after the load was applied was measured with a scale loupe. The obtained displacement amount (mm) was used to evaluate the retention performance according to the following criteria. ◎: If the displacement is less than 0.5 mm ○: If the displacement is 0.5 mm or more but less than 1.0 mm △: If the displacement is 1.0 mm or more but less than 2.0 mm ×: If the displacement is 2.0 mm or more, or if the adhesive tape falls off. Even if a product receives a "×" rating for its holding ability, it can still be used without problems depending on the application.

[0171] [Table 3]

[0172] [Table 4]

[0173] [Table 5]

[0174] [Table 6] [Industrial applicability]

[0175] The present invention provides a (meth)acrylic adhesive composition that facilitates the bonding of fluororesins and allows for the creation of a thick, uniform coating film without placing a significant burden on the environment. Furthermore, the present invention provides an adhesive tape formed using the adhesive composition. Moreover, the present invention provides a laminated sheet having the adhesive tape, and a chemical tank to which the adhesive tape or the laminated sheet is attached. In addition, the present invention provides a method for manufacturing a chemical tank using the adhesive tape and the laminated sheet. [Explanation of symbols]

[0176] 1 Adhesive tape 2 SUS304 plate 3,500g weight

Claims

1. An adhesive composition containing a base polymer and a tackifying resin, The base polymer comprises a (meth)acrylic copolymer. The (meth)acrylic copolymer has a weight-average molecular weight of less than 400,000. The tackifying resin includes a tackifying resin (T1-1) having at least one component (A) selected from the group consisting of component (A-1), component (A-1'), component (A-2), component (A-2'), component (A-3), component (A-3'), component (A-4), and component (A-4') represented by the following formula. An adhesive composition characterized by the following features. 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 In the formula, R １ ~R ７ * represents a hydrogen atom, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a polar functional group, an aliphatic hydrocarbon group having a polar functional group, or an aromatic hydrocarbon group having a polar functional group, respectively. n and l each represent an integer between 2 and 4, and n' and l' each represent an integer between 2 and 5. m and k each represent an integer between 1 and 4, and m' and k' each represent an integer between 1 and 5. * represents a linking part.

2. The (meth)acrylic copolymer has constituent units derived from a polar functional group-containing monomer, The adhesive composition according to claim 1, wherein the polar functional group-containing monomer comprises at least one selected from the group consisting of carboxyl group-containing monomers and hydroxyl group-containing monomers.

3. The (meth)acrylic copolymer has constituent units derived from alkyl (meth)acrylate, The adhesive composition according to claim 1 or 2, wherein the alkyl (meth)acrylate comprises an alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms at its ester terminus.

4. The adhesive composition according to claim 1 or 2, wherein the tackifying resin (T1-1) further comprises a constituent unit (B) derived from at least one monomer (b) selected from the group consisting of terpene monomers and vinyl monomers.

5. The adhesive composition according to claim 1 or 2, wherein the tackifying resin (T1-1) has a softening temperature of 50°C or higher and 90°C or lower.

6. The adhesive composition according to claim 1 or 2, wherein the content of the tackifying resin (T1-1) per 100 parts by mass of the base polymer is 5 parts by mass or more and 30 parts by mass or less.

7. The adhesive composition according to claim 1 or 2, wherein the tackifying resin further comprises at least one tackifying resin (T1-2) selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins.

8. The adhesive composition according to claim 1 or 2, wherein the total content of the tackifying resin relative to 100 parts by mass of the base polymer is 10 parts by mass or more and 80 parts by mass or less.

9. Furthermore, the adhesive composition according to claim 1 or 2 contains a crosslinking agent.

10. The adhesive composition according to claim 9, wherein the crosslinking agent comprises at least one selected from the group consisting of isocyanate-based crosslinking agents and epoxy-based crosslinking agents.

11. The adhesive composition according to claim 9, wherein the content of the crosslinking agent per 100 parts by mass of the base polymer is 2 parts by mass or more and 15 parts by mass or less.

12. Furthermore, the adhesive composition according to claim 1 or 2 contains a solvent.

13. The adhesive composition according to claim 12, wherein the solid content concentration is 50% by mass or more and 80% by mass or less.

14. The adhesive composition according to claim 1 or 2, wherein the adhesive composition, which does not contain a crosslinking agent, has a viscosity of 0.1 Pa·s or more and 15 Pa·s or less, as measured using a B-type viscometer at 23°C and 10 rpm.

15. An adhesive tape having an adhesive layer (Y1) formed using the adhesive composition described in claim 1.

16. The adhesive tape according to claim 15, wherein the adhesive layer (Y1) has a gel fraction of 15% by mass or more and 60% by mass or less.

17. The adhesive tape according to claim 15 or 16, wherein the adhesive layer (Y1) has a thickness of 100 μm or more and 1000 μm or less.

18. Furthermore, the adhesive tape according to claim 15 or 16, further comprising a base material.

19. The adhesive tape according to claim 18, wherein the substrate contains at least one selected from the group consisting of polyester resin, polyimide resin, polyether resin, polyolefin resin, polyurethane resin, metal, glass fiber, and carbon fiber.

20. The adhesive tape according to claim 18, wherein the base material comprises a base material in at least one shape selected from the group consisting of nonwoven fabric and woven fabric.

21. The adhesive tape according to claim 18, comprising the base material, the adhesive layer (Y1) on one surface of the base material, and the adhesive layer (Y2) formed on the other surface of the base material using an adhesive composition (X2).

22. The adhesive tape according to claim 21, wherein the adhesive layer (Y2) has a thickness of 50 μm or more and 500 μm or less.

23. The adhesive composition (X2) contains a base polymer (P2), The adhesive tape according to claim 21, wherein the base polymer (P2) comprises at least one selected from the group consisting of (meth)acrylic copolymers and styrene-based elastomers.

24. The adhesive tape according to claim 21, wherein the adhesive composition (X2) contains a tackifying resin (T2), and the tackifying resin (T2) comprises at least one tackifying resin selected from the group consisting of rosin ester resins, terpene resins, terpene phenol resins, and petroleum resins.

25. The adhesive tape according to claim 21, wherein the adhesive composition (X2) contains a silane coupling agent.

26. The adhesive tape according to claim 15, used for lining the body of a chemical tank for semiconductors or a chemical tank for the chemical industry.

27. A laminated sheet having a sheet containing fluororesin on the adhesive layer (Y1) side of the adhesive tape according to claim 15.

28. A laminated sheet according to claim 27, used for protecting an adherend.

29. A laminated sheet according to claim 28, used to protect an adherend from a chemical solution.

30. A chemical tank having the adhesive tape described in claim 15 or the laminated sheet described in claim 27 attached to the inner surface of the can body.

31. A method for manufacturing a chemical tank for semiconductors or a chemical tank for the chemical industry, comprising the step of attaching the adhesive tape described in claim 15 to the inner surface of the tank body of the chemical tank.

32. A step of producing a laminated sheet according to claim 27 by pressing a sheet containing fluororesin onto the adhesive layer (Y1) of the adhesive tape according to claim 15, A method for manufacturing a chemical tank, comprising the step of attaching the adhesive layer (Y2) of the laminated sheet to the inner surface of the tank body of the chemical tank.

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