Adhesive composition and adhesive sheet

Abstract

One embodiment of this adhesive composition contains a polyester resin having 50 mol% or more of structural units derived from a furandicarboxylic acid component per 100 mol% of structural units derived from polycarboxylic acid components constituting the polyester resin.

Description

Pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet

[0001] The present disclosure relates to a pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet.

[0002] Pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer are used in various technical fields (see, for example, Patent Documents 1 and 2). For example, pressure-sensitive adhesive sheets having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a polyester resin are known.

[0003] JP 2019-085518 A JP 2022-188511 A

[0004] In recent years, as part of efforts to address environmental issues, the use of highly biodegradable polyester resins has been considered. For example, polyester resins obtained using an isophthalic acid component are known, but these polyester resins tend to be not very biodegradable. Therefore, the present inventors have investigated the use of highly biodegradable polyester resins obtained using a furandicarboxylic acid component. However, the present inventors have found that it may be difficult to form a pressure-sensitive adhesive layer with high holding power using a pressure-sensitive adhesive composition containing a polyester resin obtained using a furandicarboxylic acid component.

[0005] One object of the present disclosure is to provide a pressure-sensitive adhesive composition containing a polyester resin obtained using a furan dicarboxylic acid component, which is capable of forming a pressure-sensitive adhesive layer having high holding power.

[0006] One embodiment of the pressure-sensitive adhesive composition of the present disclosure contains a polyester resin having 50 mol % or more of structural units derived from a furandicarboxylic acid component, relative to 100 mol % of structural units derived from a polycarboxylic acid component constituting the polyester resin.

[0007] According to the present disclosure, there is provided a pressure-sensitive adhesive composition containing a polyester resin obtained using a furandicarboxylic acid component, which is capable of forming a pressure-sensitive adhesive layer having high cohesive strength.

[0008] Generally, the terms "sheet," "film," and "tape" are sometimes used to distinguish between them based on thickness, etc., but in this specification, these terms are used without any particular distinction. In this specification, "adherend" means an object to which the PSA sheet is attached.

[0009] Each of the components described in this specification can be used alone or in combination of two or more.

[0010] In this specification, the numerical range n1 to n2 means n1 or more and n2 or less if n1<n2, and n1>n2 means n2 or more and n1 or less if n1>n2. In this specification, when multiple lower limit values ​​and multiple upper limit values ​​are given in the description of a certain element, a numerical range formed by combining a value arbitrarily selected from the given lower limit value and a value arbitrarily selected from the given upper limit value is also considered to be given.

[0011] [Pressure-sensitive adhesive composition] The pressure-sensitive adhesive composition of the present disclosure contains a specific polyester resin (hereinafter also referred to as "polyester resin (P)") described below. The pressure-sensitive adhesive composition contains at least one type of polyester resin (P), and may contain two or more types.

[0012] <Polyester Resin (P)> The polyester resin (P) contains 50 mol % or more of structural units derived from a furandicarboxylic acid component, relative to 100 mol % of structural units derived from a polycarboxylic acid component constituting the polyester resin. The furandicarboxylic acid component is at least one selected from furandicarboxylic acid and furandicarboxylic acid derivatives.

[0013] The polyester resin (P) is, for example, a polycondensate of a monomer mixture containing a polycarboxylic acid component such as a dicarboxylic acid component and a polyol component such as a diol component. The polyester resin (P) is obtained, for example, by polycondensing the monomer mixture. The polyester resin (P) preferably has a constituent unit derived from a dicarboxylic acid component such as a furandicarboxylic acid component and a constituent unit derived from a diol component.

[0014] Examples of the polycarboxylic acid component include dicarboxylic acid components and trivalent or higher polycarboxylic acid components, among which dicarboxylic acid components are preferred. Examples of the polyol component include diol components and trivalent or higher polyhydric alcohols, among which diol components are preferred.

[0015] <Furandicarboxylic Acid Component> The polyester resin (P) has a structural unit derived from a furandicarboxylic acid component. At least a furandicarboxylic acid component is used as a raw material monomer for the polyester resin (P).

[0016] The polyester resin (P) has at least one type of structural unit derived from a furan dicarboxylic acid component, and may have two or more types. In the production of the polyester resin (P), at least one type of furan dicarboxylic acid component is used, and two or more types of furan dicarboxylic acid components may be used.

[0017] As used herein, the term "furandicarboxylic acid component" refers to either furandicarboxylic acid or a furandicarboxylic acid derivative. Examples of furandicarboxylic acid include 2,5-furandicarboxylic acid, 2,4-furandicarboxylic acid, 2,3-furandicarboxylic acid, and 3,4-furandicarboxylic acid. Among these, 2,5-furandicarboxylic acid is preferred. Examples of furandicarboxylic acid derivatives include furandicarboxylic acid esters such as furandicarboxylic acid alkyl esters, furandicarboxylic acid anhydrides, furandicarboxylic acid salts such as sodium salts and potassium salts, and furandicarboxylic acid halides such as furandicarboxylic acid chloride. The alkyl group in the furandicarboxylic acid alkyl ester preferably has 1 to 15 carbon atoms, more preferably 1 to 10, and even more preferably 1 to 5 carbon atoms. The furandicarboxylic acid ester may be a furandicarboxylic acid monoester or a furandicarboxylic acid diester. The furandicarboxylic acid alkyl ester may be a furandicarboxylic acid monoalkyl ester or a furandicarboxylic acid dialkyl ester. The furandicarboxylic acid salt may be a mono- or di-salt of a dicarboxylic acid. The furandicarboxylic acid halide may be a mono- or di-halide of furandicarboxylic acid.

[0018] Specific examples of furandicarboxylic acid derivatives include dimethyl 2,5-furandicarboxylate, diethyl 2,5-furandicarboxylate, dipropyl 2,5-furandicarboxylate, dibutyl 2,5-furandicarboxylate, dihexyl 2,5-furandicarboxylate, dioctyl 2,5-furandicarboxylate, and dichloride 2,5-furandicarboxylate.

[0019] The furandicarboxylic acid component may be a component obtained using a raw material derived from a fossil fuel, or may be a biomass component obtained using a raw material derived from biomass. From the viewpoint of carbon neutrality or reduction of the environmental load, the furandicarboxylic acid component is preferably a biomass component.

[0020] A furandicarboxylic acid component is a type of aromatic dicarboxylic acid component. A pressure-sensitive adhesive composition containing a polyester resin (P) having structural units derived from an aromatic dicarboxylic acid component such as a furandicarboxylic acid component tends to be able to form a pressure-sensitive adhesive layer having even more excellent holding power, as described below.

[0021] The furandicarboxylic acid component tends to be more biodegradable than aromatic dicarboxylic acid components other than the furandicarboxylic acid component (e.g., an isophthalic acid component), and therefore, the polyester resin (P) is a preferred polyester resin from the viewpoint of reducing the environmental load.

[0022] In the polyester resin (P), the content of structural units derived from a furan dicarboxylic acid component in 100 mol % of structural units derived from a polycarboxylic acid component is 50 mol % or more, preferably 55 mol % or more or more than 55 mol %, more preferably 56 mol % or more, even more preferably 60 mol % or more, still more preferably 65 mol % or more, and particularly preferably 70 mol % or more. A pressure-sensitive adhesive composition containing such a polyester resin (P) tends to be able to form a pressure-sensitive adhesive layer having even more excellent holding power, as described below.

[0023] In the polyester resin (P), the content of structural units derived from a furandicarboxylic acid component in 100 mol% of structural units derived from a polycarboxylic acid component is 100 mol% or less. In the polyester resin (P), the content of structural units derived from a furandicarboxylic acid component in 100 mol% of structural units derived from a polycarboxylic acid component is preferably less than 100 mol%, more preferably 95 mol% or less, even more preferably 90 mol% or less, still more preferably 85 mol% or less, and particularly preferably 80 mol% or less. Such a polyester resin (P) has a glass transition temperature (Tg) described below that is not too high, and a pressure-sensitive adhesive composition containing the polyester resin (P) tends to be able to form a pressure-sensitive adhesive layer having even more excellent adhesion and flexibility.

[0024] In the polyester resin (P), the content of the structural units derived from the furan dicarboxylic acid component relative to 100 mol % of the structural units derived from the polycarboxylic acid component is, for example, 50 mol % or more and less than 100 mol %, preferably more than 55 mol % and less than 100 mol %, and more preferably 56 to 85 mol %. In this specification, the content of the structural units derived from each component in the polyester resin (P) is measured by nuclear magnetic resonance spectroscopy (NMR method).

[0025] In the above-mentioned monomer mixture, the content of the furandicarboxylic acid component in 100 mol% of the polycarboxylic acid component is, for example, 50 mol% or more, preferably 55 mol% or more or more than 55 mol%, more preferably 56 mol% or more, even more preferably 60 mol% or more, still more preferably 65 mol% or more, and particularly preferably 70 mol% or more. In the above-mentioned monomer mixture, the content of the furandicarboxylic acid component in 100 mol% of the polycarboxylic acid component is 100 mol% or less, preferably less than 100 mol%, more preferably 95 mol% or less, even more preferably 90 mol% or less, still more preferably 85 mol% or less, and particularly preferably 80 mol% or less. In the above-mentioned monomer mixture, the content of the furandicarboxylic acid component in 100 mol% of the polycarboxylic acid component is, for example, 50 mol% or more but less than 100 mol%.

[0026] <<Dicarboxylic Acid Component Other than Furandicarboxylic Acid Component>> The polyester resin (P) may further include a structural unit derived from a dicarboxylic acid component other than a furandicarboxylic acid component (hereinafter also referred to as an “other dicarboxylic acid component”). The other dicarboxylic acid component may further be used as a raw material monomer for the polyester resin (P).

[0027] The polyester resin (P) may have one or more structural units derived from the other dicarboxylic acid component. In the production of the polyester resin (P), one or more of the other dicarboxylic acid components may be used. From the viewpoint of carbon neutrality or reduction of environmental load, the other dicarboxylic acid component may be a biomass component obtained using a biomass-derived raw material.

[0028] As used herein, the term "dicarboxylic acid component" refers to both a dicarboxylic acid and a dicarboxylic acid derivative. Examples of dicarboxylic acid derivatives include dicarboxylic acid esters such as dicarboxylic acid alkyl esters, dicarboxylic acid anhydrides, dicarboxylic acid salts such as sodium salts and potassium salts, and dicarboxylic acid halides such as dicarboxylic acid chlorides. The number of carbon atoms in the alkyl group in the dicarboxylic acid alkyl ester is preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5. The dicarboxylic acid ester may be a dicarboxylic acid monoester or a dicarboxylic acid diester. The dicarboxylic acid alkyl ester may be a dicarboxylic acid monoalkyl ester or a dialkyl diester. The dicarboxylic acid salt may be a dicarboxylic acid monosalt or disalt. The dicarboxylic acid halide may be a dicarboxylic acid mono- or dihalide.

[0029] Examples of other dicarboxylic acid components include aliphatic dicarboxylic acid components (aliphatic dicarboxylic acids and / or derivatives thereof), alicyclic dicarboxylic acid components (alicyclic dicarboxylic acids and / or derivatives thereof), and aromatic dicarboxylic acid components other than furandicarboxylic acid components (aromatic dicarboxylic acids and / or derivatives thereof).

[0030] Examples of aliphatic dicarboxylic acids include malonic acid, succinic acid, glutaric acid, 3,3-dimethylglutaric acid, adipic acid, 2,2,4-trimethyladipic acid, pimelic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, diglycolic acid, 1,9-nonanedicarboxylic acid, and dimer acid. Dimer acid is a dibasic acid containing, as its main component, a dicarboxylic acid obtained by dimerization of an unsaturated fatty acid having 10 to 26 carbon atoms, preferably 12 to 24 carbon atoms, more preferably 14 to 22 carbon atoms, and even more preferably 18 carbon atoms. The unsaturated bond contained in the dicarboxylic acid may be hydrogenated. Examples of such unsaturated fatty acids include oleic acid, linoleic acid, linolenic acid, and erucic acid. The term "main component" refers to a component that accounts for 90% by mass or more, preferably 95% by mass or more, and more preferably 98% by mass or more of the total. Examples of alicyclic dicarboxylic acids include 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, and adamantanedicarboxylic acid. Examples of aromatic dicarboxylic acids other than furandicarboxylic acid include phthalic acid, isophthalic acid, terephthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid, naphthalenedicarboxylic acids (e.g., 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid), and sulfonate group-containing aromatic dicarboxylic acids.

[0031] The polyester resin (P) preferably further contains a structural unit derived from an aromatic dicarboxylic acid component other than the furan dicarboxylic acid component. The polycarboxylic acid component used in the production of the polyester resin (P) preferably further contains an aromatic dicarboxylic acid component other than the furan dicarboxylic acid component. A pressure-sensitive adhesive composition containing such a polyester resin (P) tends to be able to form a pressure-sensitive adhesive layer having even more excellent holding power, as described below.

[0032] In the polyester resin (P), the total content of the structural units derived from the furandicarboxylic acid component and the structural units derived from the aromatic dicarboxylic acid component, relative to 100 mol% of the structural units derived from the polycarboxylic acid component, is preferably 55 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, still more preferably 70 mol% or more, and particularly preferably 75 mol% or more, and is preferably 100 mol% or less, more preferably 99 mol% or less, even more preferably 95 mol% or less, and particularly preferably 90 mol% or less, for example, 55 to 100 mol%.

[0033] In the above-mentioned monomer mixture, the total proportion of the furandicarboxylic acid component and the aromatic dicarboxylic acid component in 100 mol% of the polycarboxylic acid component is preferably 55 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, still more preferably 70 mol% or more, particularly preferably 75 mol% or more, and is preferably 100 mol% or less, more preferably 99 mol% or less, even more preferably 95 mol% or less, particularly preferably 90 mol% or less, for example, 55 to 100 mol%.

[0034] In the polyester resin (P), the content of structural units derived from an aliphatic dicarboxylic acid component in 100 mol% of structural units derived from a polycarboxylic acid component is preferably 0 mol% or more, more preferably 1 mol% or more, even more preferably 5 mol% or more, particularly preferably 10 mol% or more, and is preferably 45 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, still more preferably 30 mol% or less, particularly preferably 25 mol% or less, for example, 0 to 45 mol%.

[0035] In the above-mentioned monomer mixture, the proportion of the aliphatic dicarboxylic acid component in 100 mol% of the polycarboxylic acid component is preferably 0 mol% or more, more preferably 1 mol% or more, even more preferably 5 mol% or more, particularly preferably 10 mol% or more, and is preferably 45 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, still more preferably 30 mol% or less, particularly preferably 25 mol% or less, for example, 0 to 45 mol%.

[0036] The polyester resin (P) preferably further contains a structural unit derived from a sulfonate group-containing dicarboxylic acid component. The polycarboxylic acid component used in the production of the polyester resin (P) preferably further contains a sulfonate group-containing dicarboxylic acid component. Such a polyester resin (P) has high cohesive strength, and a pressure-sensitive adhesive composition containing the polyester resin (P) tends to be able to form a pressure-sensitive adhesive layer having even more excellent holding power, as described below.

[0037] Examples of the sulfonate group-containing dicarboxylic acid component include sulfonate group-containing dicarboxylic acids and their derivatives, such as mono- or diesters of dicarboxylic acids, carboxylic acid anhydrides, mono- or di-salts of dicarboxylic acids, and mono- or dihalides of dicarboxylic acids.

[0038] The sulfonate group-containing dicarboxylic acid has two carboxy groups and a sulfonate group in the molecule. Examples of sulfonate groups include metal salts, ammonium salts, and organic amine salts of the sulfonic acid group (—SO3H). Examples of metal atoms that form metal salts include monovalent metal atoms such as alkali metal atoms (e.g., lithium, sodium, and potassium) and divalent metal atoms (e.g., calcium and magnesium). Examples of organic amine salts include alkanolamine salts (e.g., ethanolamine salts, diethanolamine salts, and triethanolamine salts) and triethylamine salts. Examples of sulfonate groups include sodium sulfonate groups, potassium sulfonate groups, magnesium sulfonate groups, calcium sulfonate groups, and ammonium sulfonate groups, with sodium sulfonate groups being particularly preferred.

[0039] The sulfonate group-containing dicarboxylic acid component is preferably a sulfonate group-containing aromatic dicarboxylic acid component, more preferably an aromatic dicarboxylic acid component having a sulfonate group bonded to a benzene ring, and even more preferably phthalic acid, isophthalic acid, or terephthalic acid, each of which has a sulfonate group bonded to a benzene ring.

[0040] Examples of sulfonate group-containing dicarboxylic acid components include sodium 5-sulfoisophthalate, sodium dimethyl 5-sulfoisophthalate, potassium dimethyl 5-sulfoisophthalate, sodium 4-sulfoisophthalate, sodium dimethyl 4-sulfoisophthalate, potassium dimethyl 4-sulfoisophthalate, sodium 2-sulfoterephthalate, potassium 2-sulfoterephthalate, sodium dimethyl 2-sulfoterephthalate, and potassium dimethyl 2-sulfoterephthalate. Of these, sodium dimethyl 5-sulfoisophthalate is preferred.

[0041] In the polyester resin (P), the content of the structural units derived from the sulfonate group-containing dicarboxylic acid component in 100 mol % of the structural units derived from the polycarboxylic acid component is preferably 1 to 10 mol %, more preferably 2 to 8 mol %, and even more preferably 3 to 7 mol %. In the monomer mixture, the content of the structural units derived from the sulfonate group-containing dicarboxylic acid component in 100 mol % of the polycarboxylic acid component is preferably 1 to 10 mol %, more preferably 2 to 8 mol %, and even more preferably 3 to 7 mol %.

[0042] <Trivalent or higher polycarboxylic acid component> The polyester resin (P) may further have a structural unit derived from a trivalent or higher polycarboxylic acid component. As a raw material monomer for the polyester resin (P), a trivalent or higher polycarboxylic acid component may be further used together with the dicarboxylic acid component. Examples of the trivalent or higher polycarboxylic acid component include trivalent or higher polycarboxylic acids and derivatives thereof. Examples of the trivalent or higher polycarboxylic acid component include trimellitic acid, pyromellitic acid, adamantanetricarboxylic acid, and trimesic acid. By using a trivalent or higher polycarboxylic acid component, for example, a polyester resin (P) having a branching point can be produced.

[0043] In the polyester resin (P), the content of the structural units derived from a trivalent or higher polycarboxylic acid component per 100 mol of the structural units derived from a dicarboxylic acid component is preferably 20 mol or less, more preferably 10 mol or less, even more preferably 5 mol or less, and particularly preferably 1 mol or less, from the viewpoint of ease of production of the polyester resin (P).

[0044] In the above-mentioned monomer mixture, the amount of the trivalent or higher polycarboxylic acid component is preferably 20 mol or less, more preferably 10 mol or less, even more preferably 5 mol or less, and particularly preferably 1 mol or less, per 100 mol of the dicarboxylic acid component, from the viewpoint of ease of production of the polyester resin (P).

[0045] In one embodiment, the polycarboxylic acid component is not a dimer acid component.

[0046] <Diol Component> The polyester resin (P) may have one or more types of structural units derived from a diol component. In producing the polyester resin (P), one or more types of diol components may be used. The diol component may be a biomass component obtained using a biomass-derived raw material from the viewpoint of carbon neutrality or reducing the environmental load.

[0047] The diol component has two hydroxy groups. Examples of the diol component include an aliphatic diol component, an alicyclic diol component, and an aromatic diol component. Other examples of the diol component include a fatty acid ester derived from castor oil, a dimer diol derived from oleic acid or erucic acid, and glycerol monostearate.

[0048] Examples of the aliphatic diol component include linear diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, diethylene glycol, and triethylene glycol; propylene glycol, dipropylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2-methyl-2-propyl-1,3-propanediol; branched diols such as 1,3,5-trimethyl-1,3-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 1,3,5-trimethyl-1,3-pentanediol, 2-methyl-1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, and 2,4-dimethyl-2-ethyl-1,3-hexanediol; and ethylene oxide or propylene oxide adducts of these diols.

[0049] Examples of the alicyclic diol component include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; and ethylene oxide or propylene oxide adducts of these diols.

[0050] Examples of the aromatic diol component include dihydroxybenzene, naphthalenediol, xylenediol, 4,4'-methylenediphenol, and 4,4'-dihydroxybiphenyl; and ethylene oxide or propylene oxide adducts of these diols.

[0051] Among the diol components, from the viewpoint of reactivity in the production of the polyester resin (P), an aliphatic diol component is preferred, an aliphatic diol component having 2 to 20 carbon atoms is more preferred, and an aliphatic diol component having 2 to 10 carbon atoms is even more preferred.

[0052] In the polyester resin (P), the content of the structural units derived from the aliphatic diol component in 100 mol % of the structural units derived from the polyol component is preferably 50 mol % or more, more preferably 60 mol % or more, even more preferably 70 mol % or more, still more preferably 80 mol % or more, and particularly preferably 90 mol % or more, from the viewpoint of ease of production of the polyester resin (P).

[0053] In the monomer mixture, the proportion of the aliphatic diol component in 100 mol % of the polyol component is preferably 50 mol % or more, more preferably 60 mol % or more, even more preferably 70 mol % or more, still more preferably 80 mol % or more, and particularly preferably 90 mol % or more, from the viewpoint of ease of production of the polyester resin (P).

[0054] <Trihydric or higher polyhydric alcohol> The polyester resin (P) may further have a structural unit derived from a trihydric or higher polyhydric alcohol. As a raw material monomer for the polyester resin (P), a trihydric or higher polyhydric alcohol may further be used together with the diol component. The trihydric or higher polyhydric alcohol has three or more hydroxy groups. Examples of trihydric or higher polyhydric alcohols include pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol, and adamantanetriol.

[0055] In the polyester resin (P), the content of the structural units derived from a trihydric or higher polyhydric alcohol per 100 mol of the structural units derived from the diol component is preferably 20 mol or less, more preferably 10 mol or less, even more preferably 5 mol or less, and particularly preferably 1 mol or less, from the viewpoint of ease of production of the polyester resin (P).

[0056] In the above-mentioned monomer mixture, the amount of the trihydric or higher polyhydric alcohol is preferably 20 mol or less, more preferably 10 mol or less, even more preferably 5 mol or less, and particularly preferably 1 mol or less, per 100 mol of the diol component, from the viewpoint of ease of production of the polyester resin (P).

[0057] <<Production of Polyester Resin (P)>> The polyester resin (P) can be produced, for example, by polycondensation of a polycarboxylic acid component containing at least a furan dicarboxylic acid component and a polyol component, optionally in the presence of a catalyst, by a known method. In one embodiment, the esterification reaction is followed by the polycondensation reaction.

[0058] The polyester resin (P) is preferably a polycondensate of a monomer mixture containing a furandicarboxylic acid component, an aliphatic dicarboxylic acid component, a sulfonate group-containing dicarboxylic acid component, and an aliphatic diol component. The polyester resin (P) preferably has structural units derived from the furandicarboxylic acid component, structural units derived from the aliphatic dicarboxylic acid component, structural units derived from the sulfonate group-containing dicarboxylic acid component, and structural units derived from the aliphatic diol component.

[0059] The blending ratio of the polycarboxylic acid component and the polyol component in the production of the polyester resin (P) is preferably 1 to 3 mol, more preferably 1.1 to 2.5 mol, of the polyol component per 1 mol of the polycarboxylic acid component.

[0060] The blending ratio of the dicarboxylic acid component and the diol component in the production of the polyester resin (P) is preferably 1 to 3 mol, more preferably 1.1 to 2.5 mol, of the diol component per 1 mol of the dicarboxylic acid component.

[0061] A catalyst may be used in the esterification reaction. Examples of the catalyst include titanium-based catalysts such as titanium tetraisopropoxide and titanium tetrabutoxide; antimony-based catalysts such as antimony trioxide; germanium-based catalysts such as germanium dioxide; and catalysts such as zinc acetate, manganese acetate, and dibutyltin oxide. One type of catalyst may be used, or two or more types may be used. The amount of catalyst used is preferably 1.0 × 10 relative to 1 mol of the total of the raw material monomers contained in the monomer mixture. -7 ~1.0 x 10 -3 mol, more preferably 5.0 × 10 -7 ~0.5 x 10 -3 mol, more preferably 1.0 × 10 -6 ~1.0 x 10 -4 mol.

[0062] The reaction temperature in the esterification reaction is preferably 150 to 280°C, more preferably 160 to 260°C, and even more preferably 170 to 240°C.

[0063] A catalyst may be used in the polycondensation reaction. Examples of the catalyst include the catalysts exemplified in the explanation of the esterification reaction. The reaction temperature in the polycondensation reaction is preferably 200 to 300°C, more preferably 220 to 280°C. In the polycondensation reaction, the pressure of the reaction system may be gradually reduced, and the reaction may be finally carried out at 500 Pa or less.

[0064] <Physical Properties of Polyester Resin (P)> In one embodiment, the glass transition temperature (Tg) of the polyester resin (P) is preferably 10°C or lower, more preferably -60 to 5°C, and even more preferably -50 to 3°C. A pressure-sensitive adhesive composition containing a polyester resin (P) having a Tg of not more than the above upper limit tends to be able to form a pressure-sensitive adhesive layer having excellent adhesion and flexibility. A polyester resin (P) having a Tg of not less than the above lower limit tends to have excellent cohesive strength. The Tg of the polyester resin (P) is a value measured using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min. Details of the measurement conditions are described in the Examples section.

[0065] In one embodiment, the glass transition temperature (Tg) of the polyester resin (P) may be greater than 10°C and equal to or less than 80°C, may be 15 to 60°C, or may be 20 to 40°C. When a polyester resin (P) having such a Tg is used and the adhesiveness or flexibility is insufficient, a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in adhesiveness and flexibility can be obtained by further using, for example, a plasticizer. Polyester resins (P) having a Tg equal to or greater than the above lower limit tend to have excellent cohesive strength.

[0066] The weight-average molecular weight (Mw) of the polyester resin (P) is preferably 5,000 or more, more preferably 7,000 or more, even more preferably 10,000 or more, even more preferably 12,000 or more, particularly preferably 13,000 or more, and preferably 200,000 or less, more preferably 140,000 or less, even more preferably 100,000 or less, even more preferably 70,000 or less, particularly preferably 50,000 or less, for example, 5,000 to 200,000. Polyester resins (P) having an Mw equal to or greater than the lower limit described above tend to have excellent cohesive strength as pressure-sensitive adhesives and excellent heat resistance and mechanical strength. Polyester resins (P) having an Mw equal to or less than the upper limit described above tend to suppress gelation during production. Mw is a polystyrene-equivalent value determined by gel permeation chromatography (GPC), and details of the measurement conditions are described in the Examples section.

[0067] The ratio Mw / Mn of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the polyester resin (P) is preferably 1.0 to 10.0, more preferably 1.3 to 8.0, and even more preferably 1.5 to 6.0. Mn is a polystyrene-equivalent value determined by gel permeation chromatography (GPC), and details of the measurement conditions are described in the Examples section.

[0068] The acid value of the polyester resin (P) is preferably 10 mgKOH / g or less, more preferably 3 mgKOH / g or less, and even more preferably 1 mgKOH / g or less. A polyester resin (P) having an acid value of the above upper limit or less tends to be less prone to hydrolysis. The acid value is a value determined by neutralization titration in accordance with JIS K 0070:1992.

[0069] The content of the polyester resin (P) in the solid content of the PSA composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. In this specification, the term "solid content" refers to all components other than the solvent and the dispersion medium.

[0070] <Plasticizer> The pressure-sensitive adhesive composition of the present disclosure may further contain a plasticizer. For example, when the Tg of the polyester resin (P) is high and the adhesiveness or flexibility is insufficient, a pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer excellent in adhesiveness and flexibility can be obtained by further using a plasticizer. The pressure-sensitive adhesive composition may contain one type of plasticizer or two or more types of plasticizer.

[0071] Examples of the plasticizer include glycerin esters such as triacetin, diacetin, and tributyrin; phthalate esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, diisononyl phthalate, di-2-ethylhexyl phthalate, diheptyl phthalate, dioctyl phthalate, diisooctyl phthalate, didecyl phthalate, and diisodecyl phthalate; and dimethyl adipate, diisobutyl adipate, di-2-ethylhexyl phthalate. Examples of suitable plasticizers include adipic acid esters such as xyl adipate, diisononyl adipate, and diisodecyl adipate; sebacate esters such as dibutyl sebacate and di-2-ethylhexyl sebacate; azelaic acid esters such as di-2-ethylhexyl azelate; citric acid esters such as triethyl citrate, tributyl citrate, triethyl acetyl citrate, and tributyl acetyl citrate; and trimellitic acid esters such as tri-2-ethylhexyl trimellitate. The plasticizer may be a mono-, di-, or triester of a di- or tricarboxylic acid, such as phthalic acid, adipic acid, sebacic acid, azelaic acid, or trimellitic acid, with an alcohol. Examples of the alcohol include linear or branched alkyl alcohols having 1 to 10 carbon atoms, such as methyl alcohol, n-butyl alcohol, isobutyl alcohol, n-heptyl alcohol, n-octyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, and isodecyl alcohol.

[0072] When the PSA composition contains a plasticizer, the content of the plasticizer is preferably 5 to 100 parts by mass, more preferably 10 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, relative to 100 parts by mass of the polyester resin (P). Such a PSA composition tends to be able to form a PSA layer that is excellent in adhesiveness and flexibility, even when the glass transition temperature (Tg) of the polyester resin (P) is high.

[0073] <Other Components> The pressure-sensitive adhesive composition of the present disclosure may further contain a polyester resin other than the polyester resin (P). The pressure-sensitive adhesive composition of the present disclosure may further contain an additive other than a plasticizer. Examples of additives other than plasticizers include crosslinkers, antioxidants, UV absorbers, stabilizers, softeners, antistatic agents, tackifiers, inorganic or organic fillers, metal powders, pigments, and dyes. The pressure-sensitive adhesive composition may contain one type of additive, or two or more types of additives.

[0074] When the pressure-sensitive adhesive composition contains additives other than a plasticizer, the content of the additives is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less, per 100 parts by mass of the polyester resin (P).

[0075] The pressure-sensitive adhesive composition may further contain a crosslinking agent. Examples of crosslinking agents include isocyanate-based crosslinking agents. Isocyanate-based crosslinking agents are compounds having two or more isocyanate groups per molecule. The number of isocyanate groups per molecule of the isocyanate-based crosslinking agent is preferably 2 to 8, more preferably 2 to 6. Examples of isocyanate-based crosslinking agents include diisocyanate compounds having two isocyanate groups per molecule and isocyanate compounds having three or more isocyanate groups per molecule.

[0076] Examples of diisocyanate compounds include aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. Examples of aliphatic diisocyanates include aliphatic diisocyanates having 4 to 30 carbon atoms, such as ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate. Examples of alicyclic diisocyanates include alicyclic diisocyanates having 7 to 30 carbon atoms, such as isophorone diisocyanate, cyclopentyl diisocyanate, cyclohexyl diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate. Examples of aromatic diisocyanates include aromatic diisocyanates having 8 to 30 carbon atoms, such as phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, naphthylene diisocyanate, diphenyl ether diisocyanate, diphenylmethane diisocyanate, and diphenylpropane diisocyanate.

[0077] Examples of the isocyanate compound having three or more isocyanate groups in one molecule include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates, and specific examples include 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, and 4,4',4"-triphenylmethane triisocyanate.

[0078] Examples of the isocyanate crosslinking agent include multimers (e.g., dimers or trimers, biurets, isocyanurates), derivatives (e.g., addition reaction products of polyhydric alcohols with two or more molecules of diisocyanate compounds), and polymers of the above-mentioned isocyanate compounds having two or more isocyanate groups. Examples of the polyhydric alcohols in the derivatives include low-molecular-weight polyhydric alcohols such as trimethylolpropane, glycerin, and pentaerythritol, as well as trivalent or higher alcohols, and high-molecular-weight polyhydric alcohols such as polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, and polyisoprene polyols. Examples of such isocyanate-based crosslinking agents include a trimer of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, a biuret or isocyanurate of hexamethylene diisocyanate or tolylene diisocyanate, a reaction product of trimethylolpropane and tolylene diisocyanate or xylylene diisocyanate (e.g., a trimolecular adduct of tolylene diisocyanate or xylylene diisocyanate), a reaction product of trimethylolpropane and hexamethylene diisocyanate (e.g., a trimolecular adduct of hexamethylene diisocyanate), polyether polyisocyanate, and polyester polyisocyanate.

[0079] When the pressure-sensitive adhesive composition contains a crosslinking agent, the content of the crosslinking agent is not particularly limited, but is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the polyester resin (P).

[0080] The pressure-sensitive adhesive composition may be, for example, a hot-melt pressure-sensitive adhesive composition.

[0081] The PSA composition may contain a solvent or a dispersion medium. Examples of the solvent or dispersion medium include an organic solvent (organic dispersion medium) and water. The PSA composition may be in the form of, for example, a solution containing a polyester resin and a solvent, or a dispersion containing a polyester resin and a dispersion medium. The PSA composition may be, for example, an emulsion-type PSA composition.

[0082] Examples of organic solvents (organic dispersion media) include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, and diphenyl ether; halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, and chlorobenzene; esters such as ethyl acetate, propyl acetate, butyl acetate, and methyl propionate; ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile; and sulfoxides such as dimethyl sulfoxide and sulfolane. Examples of water include tap water, deionized water, and ion-exchanged water. The pressure-sensitive adhesive composition may contain one or more solvents or dispersion media.

[0083] When the PSA composition contains a solvent or a dispersion medium, the content of the solvent or dispersion medium in the PSA composition is preferably 20 to 90 mass %, more preferably 30 to 85 mass %, and even more preferably 40 to 80 mass %.

[0084] [Adhesive Sheet] The adhesive sheet of the present disclosure has an adhesive layer (hereinafter also referred to as a "polyester-based adhesive layer") formed from the adhesive composition of the present disclosure. The adhesive sheet may be a double-sided adhesive sheet that does not have a substrate. The adhesive sheet may further have a substrate containing a resin material.

[0085] The substrate has a first surface and a second surface opposite the first surface.

[0086] The PSA sheet may be a single-sided PSA sheet having a polyester-based PSA layer on either the first or second surface of the substrate. The PSA sheet may be a double-sided PSA sheet having a first polyester-based PSA layer on the first surface of the substrate and a second polyester-based PSA layer on the second surface of the substrate, i.e., having a first polyester-based PSA layer, the substrate, and a second polyester-based PSA layer in this order in the stacking direction.

[0087] The pressure-sensitive adhesive sheet may have a release film on the outside of the polyester-based pressure-sensitive adhesive layer, if necessary. The release film protects the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet may have, for example, a substrate, a polyester-based pressure-sensitive adhesive layer, and a release film, in this order in the stacking direction; a first release film, a first polyester-based pressure-sensitive adhesive layer, a substrate, a second polyester-based pressure-sensitive adhesive layer, and a second release film, in this order in the stacking direction; or a first release film, a polyester-based pressure-sensitive adhesive layer, and a second release film, in this order in the stacking direction. When using the pressure-sensitive adhesive sheet, for example, the release film is peeled off from the pressure-sensitive adhesive layer, and the exposed pressure-sensitive adhesive layer is attached to the surface of an adherend.

[0088] <Substrate> The substrate contains a resin material. Examples of the resin material include vinyl chloride resins such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymer; other vinyl resins such as ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polyethylene naphthate, polybutylene terephthalate, polyethylene furanoate, and polyethylene terephthalate / isophthalate copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; cycloolefin resins; polystyrene resins; acrylonitrile-butadiene-styrene copolymers; fluoroethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and fluorinated polyethylene; polyamide resins such as nylon 6 and nylon 6,6; cellulose resins such as cellulose triacetate and cellophane; (meth)acrylic resins such as polymethyl(meth)acrylate, polyethyl(meth)acrylate, and polybutyl(meth)acrylate; polycarbonate resins; polyarylate resins; and polyimide resins. Among these, polyester resins or vinyl chloride resins are preferred, and polyethylene terephthalate or polyvinyl chloride are more preferred. The resin material may be a biomass material obtained using raw materials derived from biomass, from the viewpoint of carbon neutrality or reduction of environmental load.

[0089] In one embodiment, the substrate contains a vinyl chloride resin and a plasticizer, and has, for example, rigidity due to the vinyl chloride resin and flexibility due to the plasticizer.

[0090] In this specification, a vinyl chloride resin is a polymer having a structural unit derived from vinyl chloride. The content of the structural unit derived from vinyl chloride in 100% by mass of the structural units derived from polymerizable monomers in a vinyl chloride resin is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, even more preferably 40% by mass or more, and particularly preferably 50% by mass or more. In this specification, the content of each structural unit in a vinyl chloride resin is measured by nuclear magnetic resonance spectroscopy (NMR method). Examples of vinyl chloride resins include a homopolymer of vinyl chloride and a copolymer of vinyl chloride and a comonomer.

[0091] Examples of comonomers include vinylidene chloride, α-olefins such as ethylene and propylene, carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and fumaric acid, and esters or acid anhydrides thereof, vinyl ester-based monomers such as vinyl acetate and vinyl propionate, styrene-based monomers such as styrene, α-methylstyrene, and vinyltoluene, and (meth)acrylonitrile. One or more types of comonomers may be used.

[0092] The substrate may contain one type of resin material or two or more types of resin materials.

[0093] The content of the resin material in the substrate is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of the substrate.

[0094] The substrate may further contain additives. Examples of additives include antioxidants, UV absorbers, stabilizers, softeners, antistatic agents, tackifiers, plasticizers, inorganic or organic fillers, metal powders, pigments, and dyes. The substrate may contain one type of additive, or two or more types. The substrate may contain a plasticizer, for example, to improve its flexibility. A substrate containing a vinyl chloride resin preferably contains a plasticizer, for example, to improve its flexibility.

[0095] Examples of the plasticizer include phthalate esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, diisononyl phthalate, di-2-ethylhexyl phthalate, diheptyl phthalate, dioctyl phthalate, diisooctyl phthalate, didecyl phthalate, and diisodecyl phthalate; dimethyl adipate, diisobutyl adipate, di-2-ethylhexyl adipate, diisononyl adipate, and diisodecyl adipate; Examples of suitable plasticizers include adipic acid esters such as butyl sebacate and di-2-ethylhexyl sebacate; sebacic acid esters such as dibutyl sebacate and di-2-ethylhexyl sebacate; azelaic acid esters such as di-2-ethylhexyl azelate; citric acid esters such as triethyl citrate, tributyl citrate, acetyl triethyl citrate, and acetyl tributyl citrate; trimellitic acid esters such as tri-2-ethylhexyl trimellitate; and glycerin esters such as triacetin, diacetin, and tributyrin. The plasticizer is preferably a mono-, di-, or triester of a di- or tricarboxylic acid, such as phthalic acid, adipic acid, sebacic acid, azelaic acid, or trimellitic acid, with an alcohol. Examples of suitable alcohols include linear or branched alkyl alcohols having 1 to 10 carbon atoms, such as methyl alcohol, n-butyl alcohol, isobutyl alcohol, n-heptyl alcohol, n-octyl alcohol, 2-ethylhexyl alcohol, isononyl alcohol, and isodecyl alcohol.

[0096] The molecular weight of the plasticizer is preferably not more than 700, more preferably not more than 600, and even more preferably not more than 500. Plasticizers with such molecular weights tend to have a more excellent plasticizing effect than so-called polymer-type plasticizers.

[0097] In the base material, the content of the plasticizer is preferably 1 part by mass or more, more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, particularly preferably 15 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, even more preferably 40 parts by mass or less, particularly preferably 35 parts by mass or less, for example, 1 to 50 parts by mass, relative to 100 parts by mass of the resin material contained in the base material.

[0098] The substrate may have a single-layer structure or a multi-layer structure having two or more layers.

[0099] The surface of the substrate on which the polyester-based pressure-sensitive adhesive layer is to be formed may be subjected to a surface treatment in order to improve adhesion between the substrate and the polyester-based pressure-sensitive adhesive layer. Examples of the surface treatment include oxidation treatments by chemical or physical methods such as corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage shock exposure, and ionizing radiation treatment.

[0100] The thickness of the substrate is not particularly limited, but is preferably 1 to 1,000 μm, more preferably 5 to 500 μm, even more preferably 10 to 300 μm, and even more preferably 20 to 200 μm.

[0101] <Pressure-Sensitive Adhesive Layer> The polyester-based pressure-sensitive adhesive layer is a layer formed from the pressure-sensitive adhesive composition of the present disclosure.

[0102] The storage modulus of the polyester-based pressure-sensitive adhesive layer at 23°C is preferably 100 MPa or less, more preferably 50 MPa or less, even more preferably 10 MPa or less, still more preferably 5 MPa or less, and particularly preferably 3 MPa or less. The storage modulus of the polyester-based pressure-sensitive adhesive layer at 23°C is preferably 0.01 MPa or more, more preferably 0.05 MPa or more, even more preferably 0.1 MPa or more, still more preferably 0.3 MPa or more, and particularly preferably 0.6 MPa or more. The storage modulus of the polyester-based pressure-sensitive adhesive layer at 23°C is, for example, 0.01 to 100 MPa. The storage modulus (G') is measured under conditions of a measurement temperature of 23°C and a measurement frequency of 1 Hz. By setting the storage modulus at 23°C within the above range, for example, the initial adhesion and adhesive strength required for the pressure-sensitive adhesive sheet can be obtained.

[0103] The thickness of the polyester-based pressure-sensitive adhesive layer is not particularly limited, but is preferably 1 to 500 μm, more preferably 3 to 200 μm, even more preferably 5 to 100 μm, and particularly preferably 10 to 50 μm. Such a polyester-based pressure-sensitive adhesive layer tends to have excellent adhesiveness to the adherend. When the pressure-sensitive adhesive sheet has a first polyester-based pressure-sensitive adhesive layer and a second polyester-based pressure-sensitive adhesive layer, the above thickness refers to the thickness of each of the first and second polyester-based pressure-sensitive adhesive layers.

[0104] <Release Film> Examples of the release film include films obtained by subjecting a resin film formed from the resin materials exemplified as components constituting the above-mentioned substrate to a release treatment; foams such as polyurethane foam, vinyl foam, polyethylene foam, and polystyrene foam; metal foils such as aluminum foil, copper foil, stainless steel foil, iron foil, duralumin foil, tin foil, titanium foil, and gold foil; paper; woven fabric; and nonwoven fabric.

[0105] The release treatment may be, for example, a treatment in which a release agent is applied in the form of a layer. Examples of the release agent include silicone-based resins, long-chain alkyl-based resins, fluorine-based resins, and phosphate ester-based surfactants. One type of release agent may be used, or two or more types may be used.

[0106] The thickness of the release film is not particularly limited, but is preferably 1 to 1,000 μm, more preferably 5 to 500 μm, even more preferably 10 to 300 μm, and even more preferably 20 to 200 μm. When the PSA sheet has a first release film and a second release film, the above thickness refers to the thickness of each of the first and second release films.

[0107] <Production of Pressure-Sensitive Adhesive Sheet> The pressure-sensitive adhesive sheet of the present disclosure can be produced by a conventionally known method, except for using the pressure-sensitive adhesive composition of the present disclosure. For example, the pressure-sensitive adhesive sheet can be produced as follows. The pressure-sensitive adhesive composition of the present disclosure is prepared. The pressure-sensitive adhesive composition is applied to the first or second surface of a substrate and dried to form a pressure-sensitive adhesive layer, a release film is attached to the surface of the pressure-sensitive adhesive layer, and a curing treatment is performed as necessary. Alternatively, the pressure-sensitive adhesive composition is applied to the surface of a release film and dried to form a pressure-sensitive adhesive layer, a substrate is attached to the surface of the pressure-sensitive adhesive layer, and a curing treatment is performed as necessary. In this way, a pressure-sensitive adhesive sheet having a substrate, a pressure-sensitive adhesive layer, and a release film is obtained.

[0108] For example, a pressure-sensitive adhesive sheet can be produced as follows: A pressure-sensitive adhesive composition according to the present disclosure is prepared. The pressure-sensitive adhesive composition is applied to the surface of a release film and dried to form a pressure-sensitive adhesive layer. Another release film is then laminated to the surface of the pressure-sensitive adhesive layer, and a curing treatment is performed as necessary. In this manner, a double-sided pressure-sensitive adhesive sheet having no substrate is obtained.

[0109] Examples of methods for applying the pressure-sensitive adhesive composition include spin coating, knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating.

[0110] As for the drying conditions after application of the PSA composition, the drying temperature is preferably 50 to 150°C, more preferably 60 to 120°C, and the drying time is preferably 1 to 10 minutes, more preferably 2 to 7 minutes. As for the conditions for the curing treatment, the curing temperature is preferably 5 to 60°C, more preferably 15 to 40°C, and the curing time is preferably 1 to 30 days, more preferably 3 to 20 days.

[0111] <Uses of Pressure-Sensitive Adhesive Sheet> The pressure-sensitive adhesive sheet of the present disclosure can be used for various purposes. The pressure-sensitive adhesive sheet of the present disclosure can be used, for example, as a marking film for display or decoration. Examples of substrates to which the marking film can be attached include vehicles such as bicycles, motorcycles, automobiles, buses, and trains; household items such as furniture and home appliances; office supplies such as cabinets, desks, and personal computers; buildings such as houses; everyday items such as mobile phones and mobile phone covers; and exterior or interior parts thereof. Examples of materials for the substrate include plastic, glass, and metals such as stainless steel and aluminum.

[0112] The pressure-sensitive adhesive sheet of the present disclosure can be used as, for example, a surface protection sheet.The uses of the surface protection sheet include, for example, a protection sheet for plastic film or glass plate, a protection sheet for optical components, a protection sheet for semiconductor wafer, a protection sheet for electronic components and electronic equipment such as electronic substrates, and a protection sheet for metal plates such as stainless steel and aluminum.Therefore, the adherend to which the surface protection sheet is attached includes, for example, a plastic film, a glass plate, an optical component, a semiconductor wafer, an electronic substrate, and other electronic components and electronic equipment, and a metal plate such as stainless steel and aluminum.

[0113] Examples of optical components include inorganic transparent electrode films such as indium tin oxide (ITO) electrode films, organic transparent electrode films such as polythiophene, polarizing plates, retardation plates, elliptically polarizing plates, light diffusion films, optical compensation films, brightness enhancement films, electromagnetic wave shielding films, near-infrared absorbing films, antireflection films, and antiglare films.

[0114] When the pressure-sensitive adhesive sheet of the present disclosure further comprises an optical member, it can be used, for example, as an optical sheet. The pressure-sensitive adhesive sheet of the present disclosure can also be used as a pressure-sensitive adhesive sheet for optical members used for bonding the optical member.

[0115] Preferred substrates for the pressure-sensitive adhesive sheet include, for example, vehicle components for automobiles, buses, trains, etc., aircraft components, ship components, and building components, and more preferred are vehicle interior materials, aircraft interior materials, ship interior materials, and building interior materials.

[0116] [Examples] The present disclosure relates to, for example, the following [1] to [8]. [1] A pressure-sensitive adhesive composition containing a polyester resin having 50 mol% or more of structural units derived from a furandicarboxylic acid component, based on 100 mol% of structural units derived from a polycarboxylic acid component constituting the polyester resin. [2] The pressure-sensitive adhesive composition according to [1] above, in which the polyester resin has more than 55 mol% but less than 100 mol% of structural units derived from the furandicarboxylic acid component, based on 100 mol% of structural units derived from the polycarboxylic acid component. [3] The pressure-sensitive adhesive composition according to [1] above, in which the polyester resin is a polycondensate of a monomer mixture including the furandicarboxylic acid component, an aliphatic dicarboxylic acid component, a sulfonate group-containing dicarboxylic acid component, and an aliphatic diol component. [4] The pressure-sensitive adhesive composition according to [3] above, wherein the polyester resin contains 56 to 85 mol % of structural units derived from the furandicarboxylic acid component and 1 to 10 mol % of structural units derived from the sulfonate group-containing dicarboxylic acid component, based on 100 mol % of structural units derived from the polycarboxylic acid component. [5] The pressure-sensitive adhesive composition according to any one of [1] to [4] above, wherein the furandicarboxylic acid component is at least one selected from furandicarboxylic acid and a furandicarboxylic acid derivative. [6] The pressure-sensitive adhesive composition according to any one of [1] to [5] above, further comprising a plasticizer. [7] A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of [1] to [6] above. [8] The pressure-sensitive adhesive sheet according to [7] above, wherein the pressure-sensitive adhesive layer has a storage modulus at 23°C of 100 MPa or less.

[0117] The pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of the present disclosure will be described in more detail below based on examples, but the pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of the present disclosure are not limited to these examples in any way.

[0118] [Methods for measuring various physical properties, etc.] <Content ratio of structural units in polyester resin> The content ratio (amount of structural units) of structural units derived from each raw material monomer in the polyester resin was calculated by nuclear magnetic resonance spectroscopy (NMR method) under the following conditions. Measuring device: ECZL-500G (manufactured by JEOL Ltd.) Measuring method: 1 H-NMR Accumulation number: 16 Sample concentration: 10 mg / mL Dilution solvent: dimethyl sulfoxide (DMSO)-d6

[0119] <Glass Transition Temperature (Tg) of Polyester Resin> The polyester resin was placed in a simple hermetic pan and measured using a differential scanning calorimeter (DSC). Under a nitrogen stream, the temperature was raised from -60°C to 200°C at a rate of 10°C / min, and the thermal change was measured to plot a DSC curve of "endothermal heat generation" versus "temperature." The characteristic inflection point observed at this time was taken as the glass transition temperature (Tg) of the polyester resin. The Tg value was obtained from the DSC curve by the midpoint method.

[0120] <Number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polyester resin> The polystyrene-equivalent number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polyester resin were determined by gel permeation chromatography (GPC) under the following conditions: Measurement device: HLC-8320GPC (manufactured by Tosoh Corporation) GPC column configuration: the following four columns in series (all manufactured by Tosoh Corporation): (1) TSKgel HxL-H (guard column) (2) TSKgel GMHxL (3) TSKgel GMHxL (4) TSKgel G2500HxL Flow rate: 1.0 mL / min Column temperature: 40°C Sample concentration: 1.5% (w / v) (diluted with tetrahydrofuran) Mobile phase solvent: tetrahydrofuran Standard polystyrene equivalent

[0121] <Biodegradability (Marine Degradability) of Polyester Resin Particles> 30 mg of polyester resin obtained in the following Production Example and 250 mL of seawater were placed in a brown sample bottle, and after setting up a measurement head, the sample bottle was left to stand in a thermostatic chamber at 20°C for 30 days, and the biochemical oxygen demand (BOD) value was calculated. The theoretical oxygen demand was calculated by calculating the amount of CO2 from the molecular weight of the polyester resin. The biodegradability (%) was calculated using the following formula. An Oxi-Topi (manufactured by WTW) was used as the measurement head. Biodegradability (%) = [(sample BOD value (mg) - blank BOD value (mg)) / theoretical oxygen demand of sample (mg)] x 100

[0122] [Production Example 1] A flask equipped with a heater, thermometer, stirrer, rectification column, nitrogen inlet tube, and vacuum device was charged with 0.5 mol of 2,5-dimethyl furandicarboxylate (FDCA-Me; biomass component), 0.44 mol of sebacic acid (SebA), 0.06 mol of 5-dimethylsodium sulfoisophthalate (SIPM), 1.7 mol of diethylene glycol (DEG), and 0.000035 mol of Orgatix TA-8 (titanium tetraisopropoxide, manufactured by Matsumoto Fine Chemical) as a polymerization catalyst. The temperature in the flask was gradually increased to 180 ° C. while introducing nitrogen, and the esterification reaction was carried out for 3 hours. Thereafter, the temperature in the flask was increased to 230 ° C., and the pressure in the flask was reduced to 100 Pa, and the polycondensation reaction was carried out for 3 hours. In this way, polyester resin (1) was produced. The polyester resin (1) had a glass transition temperature (Tg) of -25°C, a number average molecular weight (Mn) of 22,700, and a weight average molecular weight (Mw) of 42,900.

[0123] [Production Examples 2 to 10] Polyester resins (2) to (10) were produced in the same manner as in Production Example 1, except that the types and / or amounts of raw material monomers were changed as shown in Table 1.

[0124] [Example 1] Polyester resin (1) and tetrahydrofuran (THF) were placed in a sample bottle to prepare a pressure-sensitive adhesive composition in the form of a solution of polyester resin (1) with a solids concentration of 30% by mass. The resulting solution was applied to a 50 μm thick polyethylene terephthalate (PET) film so that the dry thickness was 20 μm, and the film was dried at 100 ° C for 2 minutes to remove the solvent, forming a pressure-sensitive adhesive layer. A release-treated PET film was attached to the surface of the pressure-sensitive adhesive layer opposite the surface in contact with the PET film. In this way, a pressure-sensitive adhesive sheet having a 50 μm thick PET film, a 20 μm thick pressure-sensitive adhesive layer, and a release-treated PET film was produced.

[0125] Examples 2 to 8, Comparative Example 1 and Reference Example 1 Pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets were produced in the same manner as in Example 1, except that polyester resin (1) was changed to any of polyester resins (2) to (10) shown in Table 1. However, in Example 4, 60 parts by mass of a plasticizer (triacetin) was blended with 100 parts by mass of polyester resin (4).

[0126] [Evaluation] <Adhesive Strength> The pressure-sensitive adhesive sheets of the Examples or Comparative Examples were cut to a size of 20 mm x 100 mm, and the release-treated PET film was peeled off from the pressure-sensitive adhesive layer. The exposed pressure-sensitive adhesive layer was attached to a SUS plate and pressed back and forth with a 2 kg roller three times to prepare test pieces. Two test pieces were prepared for each test. One test piece was left in an environment of 23°C and 50% RH for 20 minutes (referred to as "initial" in Table 1), and the other test piece was left in an environment of 23°C and 50% RH for 24 hours (referred to as "after 24 hours" in Table 1). The edge of the pressure-sensitive adhesive sheet was pulled at a speed of 300 mm / min in a direction 180° relative to the surface of the SUS plate, and the adhesive strength (N / 20 mm) was measured.

[0127] <Holding Power> In an environment of 23°C and 50% RH, the release-treated PET film was peeled off from the adhesive layer of the adhesive sheet of each Example or Comparative Example, and the exposed adhesive layer was attached to a SUS plate. A 2 kg roller was then rolled back and forth three times to perform a pressure-bonding process. The adhesion area was 20 mm x 20 mm. After 20 minutes of application, a 500 g load was applied parallel to the adhesive layer surface in a dry environment at 40°C, and the distance (mm) of displacement of the adhesive sheet from its original position after 1 hour was measured. The smaller the displacement distance of the adhesive sheet, the higher the holding power of the adhesive sheet. If the adhesive sheet fell within 1 hour, the time required for the adhesive sheet to fall after the load was applied was recorded.

[0128] <Storage Modulus> The polyester resin obtained in the above Production Example and THF were placed in a sample bottle to prepare a solution with a polyester resin solids concentration of 30% by mass. The obtained solution was applied to a release-treated PET film so that the dry thickness was 25 μm, and the solution was dried in a 100°C environment for 2 minutes to remove the solvent, forming a pressure-sensitive adhesive layer. A release-treated PET film was attached to the side of the pressure-sensitive adhesive layer opposite the side in contact with the PET film. In this manner, multiple pressure-sensitive adhesive sheets were produced, each having a release-treated PET film, a 25 μm-thick pressure-sensitive adhesive layer, and a release-treated PET film. A 1 mm-thick test piece for measuring the storage modulus was prepared by laminating multiple pressure-sensitive adhesive layers using multiple pressure-sensitive adhesive sheets. The storage modulus (G') at 23°C was measured using this test piece using a TA Instruments DHR2 rheometer. The measurement frequency was 1 Hz.

[0129]

[0130] FDCA-Me: 2,5-dimethyl furandicarboxylate SebA: Sebacic acid SIPM: 5-sodium dimethyl sulfoisophthalate IPA: Isophthalic acid Dimer acid: Dibasic acid containing as its main component a dicarboxylic acid obtained by dimerization of unsaturated fatty acids having 18 carbon atoms DEG: Diethylene glycol EG: Ethylene glycol

Claims

1. A pressure-sensitive adhesive composition containing a polyester resin having 50 mol % or more of structural units derived from a furandicarboxylic acid component out of 100 mol % of structural units derived from a polycarboxylic acid component constituting the polyester resin.

2. The pressure-sensitive adhesive composition according to claim 1, wherein the polyester resin contains more than 55 mol% and less than 100 mol% of structural units derived from the furandicarboxylic acid component, based on 100 mol% of structural units derived from the polycarboxylic acid component.

3. The pressure-sensitive adhesive composition according to claim 2, wherein the polyester resin is a polycondensate of a monomer mixture containing the furandicarboxylic acid component, an aliphatic dicarboxylic acid component, a sulfonate group-containing dicarboxylic acid component, and an aliphatic diol component.

4. The pressure-sensitive adhesive composition according to claim 3, wherein the polyester resin contains 56 to 85 mol % of structural units derived from the furandicarboxylic acid component and 1 to 10 mol % of structural units derived from the sulfonate group-containing dicarboxylic acid component, relative to 100 mol % of structural units derived from the polycarboxylic acid component.

5. The pressure-sensitive adhesive composition according to claim 1, wherein the furandicarboxylic acid component is at least one selected from furandicarboxylic acid and furandicarboxylic acid derivatives.

6. The pressure-sensitive adhesive composition according to claim 1, further comprising a plasticizer.

7. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 6.

8. The pressure-sensitive adhesive sheet according to claim 7, wherein the pressure-sensitive adhesive layer has a storage modulus at 23°C of 100 MPa or less.

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