Method for producing water-soluble polymers, method for producing superabsorbent polymers, water-soluble polymers, and superabsorbent polymers

Abstract

Provided are: a method for producing a water-soluble polymer, the method making it possible to produce a water-soluble polymer under mild conditions from an adhesive as waste; a method for producing a water-absorbent polymer, the method making it possible to produce a water-absorbent polymer under mild conditions from an adhesive; a water-soluble polymer that can be produced from an adhesive; and a water-absorbent polymer that can be produced from an adhesive. The method for producing a water-soluble polymer according to an embodiment of the present invention includes bringing an adhesive treatment solution including a liquid having a Hansen solubility parameter of 31 or less and an alkali compound, the concentration of alkali compound in the adhesive treatment solution being 0.001-20 wt%, into contact with an adhesive.

Description

[Technical Field]

[0001] This invention relates to a method for producing water-soluble polymers. This invention also relates to a method for producing superabsorbent polymers. This invention also relates to water-soluble polymers. This invention also relates to superabsorbent polymers. [Background technology]

[0002] Hydrophilic polymers, which have an affinity for water, include water-soluble polymers used as raw materials for various industrial products, and superabsorbent polymers used in absorbent materials such as disposable diapers. As a method for producing such hydrophilic polymers, for example, a technique has been reported in which monomers are polymerized by heating them to about 175°C in the presence of a catalyst to produce hydrophilic polymers (Patent Document 1).

[0003] However, the technology described in Patent Document 1 requires the selection of extremely high temperature conditions, such as exceeding 150°C, which limits the improvement in the manufacturing efficiency of hydrophilic polymers.

[0004] Furthermore, in recent years, there has been a growing desire to produce polymers from waste materials from the perspective of reducing environmental impact. In particular, hydrophilic polymers such as water-soluble polymers and superabsorbent polymers, which have a wide range of industrial applications, would make a significant contribution to reducing environmental impact if they could be recycled from waste materials under mild conditions. In this case, it would be highly desirable if the large quantities of waste materials that can be generated could be utilized. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 3917178 [Overview of the project] [Problems that the invention aims to solve]

[0006] We conducted research to identify waste materials that can be used to produce hydrophilic polymers, such as water-soluble polymers and superabsorbent polymers, under mild conditions, and that are likely to be generated in large quantities. As a result, we focused on adhesive waste, including adhesive contained in adhesive tapes collected after use, adhesive residue left on surfaces when adhesive tapes are peeled off, and adhesive adhering to adhesive manufacturing equipment. We then diligently investigated a technology to regenerate hydrophilic polymers, such as water-soluble polymers and superabsorbent polymers, from such adhesive waste under mild conditions, leading to the completion of the present invention.

[0007] The object of the present invention is to provide a method for producing a water-soluble polymer from an adhesive under mild conditions, a method for producing a superabsorbent polymer from an adhesive under mild conditions, a water-soluble polymer that can be produced from an adhesive, and a superabsorbent polymer that can be produced from an adhesive. [Means for solving the problem]

[0008] A method for producing a water-soluble polymer according to an embodiment of the present invention is: The adhesive treatment solution, which contains a liquid with a Hansen solubility parameter value of 31 or less and an alkaline compound, and in which the concentration of the alkaline compound is 0.001% to 20% by weight, is brought into contact with the adhesive.

[0009] In one embodiment, the Hansen solubility parameter value of the liquid is 15 or more and 25 or less, and the liquid contains a lower alcohol.

[0010] In one embodiment, the adhesive is composed of an acrylic adhesive.

[0011] In one embodiment, the concentration of the alkaline compound in the treatment solution is 0.01% to 10% by weight.

[0012] The water-soluble polymer according to an embodiment of the present invention is a water-soluble polymer obtained by the method for producing a water-soluble polymer according to an embodiment of the present invention, and includes a structural unit (1) represented by the following formula and a structural unit (2) represented by the following formula. [Chemical formula] (In the formula, R 1 represents a hydrogen atom or a methyl group. R 2 represents an alkyl group having 1 to 12 carbon atoms. M represents a hydrogen atom or a cation.)

[0013] The method for producing a water-absorbent polymer according to an embodiment of the present invention reacts a water-soluble polymer obtained by the method for producing a water-soluble polymer in an embodiment of the present invention with a crosslinking agent.

[0014] The method for producing a water-absorbent polymer according to an embodiment of the present invention is an adhesive treatment liquid containing a liquid having a Hansen solubility parameter value of 31 or less and an alkali compound, wherein the concentration of the alkali compound in the adhesive treatment liquid is 0.001% by weight to 20% by weight, and a crosslinking agent and an adhesive are brought into contact with each other.

[0015] The water-absorbent polymer according to an embodiment of the present invention includes a structural unit (1) represented by the following formula, a structural unit (2) represented by the following formula, and a crosslinked structure formed by the reaction of the structural unit (1) and / or the structural unit (2) with a crosslinking agent. [Chemical formula] (In the formula, R 1 represents a hydrogen atom or a methyl group. R 2 represents an alkyl group having 1 to 12 carbon atoms. M represents a hydrogen atom or a cation.) [Advantages of the Invention]

[0016] According to the present invention, it is possible to provide a method for producing a water-soluble polymer from an adhesive under mild conditions, a method for producing a superabsorbent polymer from an adhesive under mild conditions, a water-soluble polymer that can be produced from an adhesive, and a superabsorbent polymer that can be produced from an adhesive. [Modes for carrying out the invention]

[0017] Where the term "weight" appears in this specification, it may be interpreted as "mass," which is the commonly used SI unit for weight.

[0018] In this specification, the expression "(meth)acrylic" means "acrylic and / or methacrylic," the expression "(meth)acrylate" means "acrylate and / or methacrylate," the expression "(meth)allyl" means "allyl and / or methallyl," and the expression "(meth)acrolein" means "acrolein and / or metacrolein."

[0019] ≪≪1. Method for producing water-soluble polymers≫≫ In the method for producing a water-soluble polymer according to an embodiment of the present invention, a water-soluble polymer is produced from an adhesive by bringing an adhesive into contact with an adhesive treatment solution. According to the method for producing a water-soluble polymer according to an embodiment of the present invention, various types of adhesives can be recycled to produce a water-soluble polymer from the adhesive.

[0020] ≪1-1. Adhesives≫ As an adhesive used as a raw material for the water-soluble polymer, any suitable adhesive can be used as long as it does not impair the effects of the present invention. Typical examples of such adhesives include adhesives that are considered waste, such as adhesives contained in adhesive tapes collected after use, adhesives that remain on a substrate when the adhesive tape is peeled off the substrate to which the tape was attached, and adhesives that adhere to adhesive manufacturing equipment.

[0021] Adhesive tape typically comprises an adhesive layer composed of an adhesive and a substrate. The adhesive layer may consist of only one layer or two or more layers.

[0022] Examples of adherends include silicon wafers, semiconductor circuit boards, electronic devices such as ceramic capacitors, optical films, and optical glass, where even a small amount of adhesive residue could potentially lead to a decrease in the adherend's functionality.

[0023] Examples of adhesive manufacturing equipment include polymerization kettle, compounding equipment, and coating machine.

[0024] The adhesive can take various forms, such as an adhesive layer contained in adhesive tape, adhesive residue left on the adherend, or adhesive adhering to manufacturing equipment such as polymerization kettle, compounding device, or coating machine, and therefore its size and shape can vary. For example, if the adhesive is in the form of an adhesive layer contained in adhesive tape, the thickness of the adhesive tape is preferably 1 μm to 2000 μm, as this allows the effects of the present invention to be more fully realized.

[0025] The adhesive is preferably composed of at least one selected from the group consisting of acrylic adhesives, urethane adhesives, rubber adhesives, and silicone adhesives, more preferably composed of at least one selected from the group consisting of acrylic adhesives, urethane adhesive compositions, and silicone adhesive compositions, and even more preferably composed of an acrylic adhesive.

[0026] The adhesive can be formed by any suitable method. For example, such a method involves applying an adhesive composition (at least one selected from the group consisting of acrylic adhesive compositions, urethane adhesive compositions, rubber adhesive compositions, and silicone adhesive compositions) onto any suitable substrate, heating and drying as necessary, and curing as necessary to form an adhesive (specifically, an adhesive layer) on the substrate. For example, such application methods include gravure roll coaters, reverse roll coaters, kiss roll coaters, dip roll coaters, bar coaters, knife coaters, air knife coaters, spray coaters, comma coaters, direct coaters, roll brush coaters, and die coaters.

[0027] <Acrylic adhesive> Acrylic adhesives are formed from acrylic adhesive compositions.

[0028] The acrylic adhesive composition preferably contains an acrylic polymer and a crosslinking agent, as this allows for better expression of the effects of the present invention.

[0029] Acrylic polymers can be referred to as so-called base polymers in the field of acrylic adhesives. The acrylic polymer may consist of only one type or two or more types.

[0030] The content of acrylic polymer in the acrylic adhesive composition is preferably 50% to 100% by weight, more preferably 60% to 100% by weight, even more preferably 70% to 100% by weight, particularly preferably 80% to 100% by weight, and most preferably 90% to 100% by weight, based on solid content.

[0031] As the acrylic polymer, any suitable acrylic polymer can be used, as long as it does not impair the effects of the present invention.

[0032] The weight-average molecular weight of the acrylic polymer is preferably 100,000 to 3,000,000, more preferably 150,000 to 2,000,000, even more preferably 200,000 to 1,500,000, and particularly preferably 250,000 to 1,000,000, in order to better exhibit the effects of the present invention.

[0033] The acrylic polymer is preferably an acrylic polymer formed by polymerization from composition (A), which is preferable in that it can better exhibit the effects of the present invention, and which comprises (a) an alkyl (meth)acrylate ester having 4 to 12 carbon atoms in the alkyl group of the alkyl ester portion, and (b) at least one selected from the group consisting of (meth)acrylate esters having an OH group and (meth)acrylic acid. Each of (a) and (b) may be one or two or more, independently of each other.

[0034] Examples of alkyl (meth)acrylate esters (component a) having 4 to 12 carbon atoms in the alkyl group of the alkyl ester portion include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, and dodecyl (meth)acrylate. Among these, n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate are preferred in terms of being able to better exhibit the effects of the present invention, and more preferably n-butyl acrylate and 2-ethylhexyl acrylate.

[0035] At least one component (b) selected from the group consisting of (meth)acrylic acid esters and (meth)acrylic acid having an OH group, include, for example, (meth)acrylic acid esters having an OH group such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate, and (meth)acrylic acid. Among these, hydroxyethyl (meth)acrylate and (meth)acrylic acid are preferred in terms of being able to better express the effects of the present invention, and more preferably hydroxyethyl acrylate and acrylic acid.

[0036] Composition (A) may contain copolymerizable monomers other than components (a) and (b). The copolymerizable monomer may be one type or two or more types.Such copolymerizable monomers include, for example, carboxyl group-containing monomers such as itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and their acid anhydrides (e.g., acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride) (excluding (meth)acrylic acid); (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-hydroxyethyl(meth) Amylamide-containing monomers such as acrylamide; amino group-containing monomers such as (meth)aminoethyl acrylate, (meth)dimethylaminoethyl acrylate, and (meth)butylaminoethyl acrylate; epoxy group-containing monomers such as (meth)glycidyl acrylate and (meth)methylglycidyl acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinyl-2-pyrrolidone, (meth)acryloylmorpholine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, N-vinyl Examples include heterocyclic vinyl monomers such as midazole, vinylpyridine, vinylpyrimidine, and vinyloxazole; sulfonic acid group-containing monomers such as sodium vinylsulfonate; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; imide group-containing monomers such as cyclohexyl maleimide and isopropyl maleimide; isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate; (meth)acrylic acid esters having alicyclic hydrocarbon groups such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid esters having aromatic hydrocarbon groups such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, and benzyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyltoluene; olefins and dienes such as ethylene, butadiene, isoprene, and isobutylene; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride.

[0037] Polyfunctional monomers can also be used as copolymerizable monomers. A polyfunctional monomer is a monomer having two or more ethylenically unsaturated groups in one molecule. Any suitable ethylenically unsaturated group can be used as the ethylenically unsaturated group, as long as it does not impair the effects of the present invention. Examples of such ethylenically unsaturated groups include radical polymerizable functional groups such as vinyl groups, propenyl groups, isopropenyl groups, vinyl ether groups (vinyloxy groups), and allyl ether groups (allyloxy groups). Examples of polyfunctional monomers include hexanediol di(meth)acrylate, butanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate. Such polyfunctional monomers may be present individually or in combination of two or more types.

[0038] As copolymerizable monomers, alkoxyalkyl (meth)acrylates may also be used. Examples of alkoxyalkyl (meth)acrylates include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, and 4-ethoxybutyl (meth)acrylate. There may be only one alkoxyalkyl (meth)acrylate or two or more.

[0039] The content of the alkyl (meth)acrylate (component a) in which the alkyl group of the alkyl ester portion has 4 to 12 carbon atoms is preferably 50% by weight or more, more preferably 60% to 100% by weight, even more preferably 70% to 100% by weight, and particularly preferably 80% to 100% by weight, relative to the total amount (100% by weight) of the monomer components constituting the acrylic polymer, in order to better express the effects of the present invention.

[0040] The content of at least one component (component b) selected from the group consisting of (meth)acrylic acid esters having an OH group and (meth)acrylic acid is preferably 0.1% by weight or more, more preferably 1.0% to 50% by weight, even more preferably 1.5% to 40% by weight, and particularly preferably 2.0% to 30% by weight, relative to the total amount (100% by weight) of monomer components constituting the acrylic polymer, in order to better express the effects of the present invention.

[0041] The acrylic polymer is preferably contained in an amount of 5% to 95% by weight, more preferably 10% to 95% by weight, even more preferably 15% to 95% by weight, even more preferably 20% to 95% by weight, even more preferably 25% to 95% by weight, even more preferably 30% to 95% by weight, particularly preferably 35% to 90% by weight, and most preferably 40% to 90% by weight, relative to the total amount of monomer components (100% by weight).

[0042] Composition (A) may contain any other suitable components, as long as they do not impair the effects of the present invention. Examples of such other components include polymerization initiators, chain transfer agents, and solvents. The content of these other components may be any suitable amount, as long as they do not impair the effects of the present invention.

[0043] Depending on the type of polymerization reaction, the polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator (photoinitiator). There may be only one polymerization initiator or two or more.

[0044] A thermal polymerization initiator can preferably be used when obtaining an acrylic polymer by solution polymerization. Examples of such thermal polymerization initiators include azo polymerization initiators, peroxide polymerization initiators (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), and redox polymerization initiators. Among these thermal polymerization initiators, the azo polymerization initiator disclosed in Japanese Patent Application Publication No. 2002-69411 is particularly preferred. Such azo polymerization initiators are preferred because their decomposition products are less likely to remain in the acrylic polymer as a cause of outgassing. Examples of azo polymerization initiators include 2,2'-azobisisobutyronitrile (hereinafter sometimes referred to as AIBN), 2,2'-azobis-2-methylbutyronitrile (hereinafter sometimes referred to as AMBN), 2,2'-azobis(2-methylpropionic acid)dimethyl, and 4,4'-azobis-4-cyanovaleric acid. The amount of azo polymerization initiator used is preferably 0.01 to 5.0 parts by weight, more preferably 0.05 to 4.0 parts by weight, even more preferably 0.1 to 3.0 parts by weight, particularly preferably 0.15 to 3.0 parts by weight, and most preferably 0.20 to 2.0 parts by weight, relative to the total amount of monomer components constituting the acrylic polymer (100 parts by weight).

[0045] Photopolymerization initiators can preferably be used when obtaining acrylic polymers by active energy ray polymerization. Examples of photopolymerization initiators include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and the like.

[0046] Examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, and anisole methyl ether. Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloroacetophenone. Examples of α-ketol-based photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. Examples of aromatic sulfonyl chloride-based photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. Examples of benzoin-based photopolymerization initiators include benzoin. Examples of benzyl-based photopolymerization initiators include benzyl. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. Examples of ketal-based photopolymerization initiators include benzyldimethylketal. Examples of thioxanthone-based photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0047] The amount of photopolymerization initiator used is preferably 0.01 to 3.0 parts by weight, more preferably 0.015 to 2.0 parts by weight, even more preferably 0.02 to 1.5 parts by weight, particularly preferably 0.025 to 1.0 part by weight, and most preferably 0.03 to 0.50 parts by weight, relative to the total amount of monomer components constituting the acrylic polymer (100 parts by weight).

[0048] The acrylic adhesive composition may contain a crosslinking agent. By using a crosslinking agent, the cohesive force of the acrylic adhesive can be improved, and the effects of the present invention can be further exhibited. There may be only one type of crosslinking agent, or there may be two or more types.

[0049] Examples of crosslinking agents include polyfunctional isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, as well as urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, carbodiimide crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, and amine crosslinking agents. Among these, at least one (component c) selected from the group consisting of polyfunctional isocyanate crosslinking agents and epoxy crosslinking agents is preferred in terms of being able to better express the effects of the present invention.

[0050] Examples of polyfunctional isocyanate crosslinking agents include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; alicyclic polyisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated xylene diisocyanate; and aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. Examples of polyfunctional isocyanate crosslinking agents include commercially available products such as trimethylolpropane / tolylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L"), trimethylolpropane / hexamethylene diisocyanate adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), trade name "Coronate HX" (manufactured by Nippon Polyurethane Industry Co., Ltd.), and trimethylolpropane / xylylene diisocyanate adduct (manufactured by Mitsui Chemicals, Inc., trade name "Takenate 110N").

[0051] Examples of epoxy crosslinking agents (polyfunctional epoxy compounds) include N,N,N',N'-tetraglycidyl-m-xylenediline, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol polyglycidyl ether. Examples include diglycidyl ethers, glycerol polyglycidyl ethers, pentaerythritol polyglycidyl ethers, polyglycerol polyglycidyl ethers, sorbitan polyglycidyl ethers, trimethylolpropane polyglycidyl ethers, diglycidyl adipate esters, diglycidyl o-phthalate esters, triglycidyl-tris(2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ethers, bisphenol-S-diglycidyl ethers, and epoxy resins having two or more epoxy groups in the molecule. Commercially available epoxy crosslinking agents include the trade name "Tetrad C" (manufactured by Mitsubishi Gas Chemical Company, Inc.).

[0052] The amount of crosslinking agent in the acrylic adhesive composition can be any appropriate amount, as long as it does not impair the effects of the present invention. For example, in terms of better exhibiting the effects of the present invention, the amount is preferably 0.1 to 5.0 parts by weight, more preferably 0.2 to 4.5 parts by weight, even more preferably 0.3 to 4.0 parts by weight, and particularly preferably 0.4 to 3.5 parts by weight, relative to the solid content (100 parts by weight) of the acrylic polymer.

[0053] The acrylic adhesive composition may contain any other suitable components as long as they do not impair the effects of the present invention. Examples of such other components include polymer components other than acrylic polymers, crosslinking accelerators, crosslinking catalysts, silane coupling agents, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), antioxidants, inorganic fillers, organic fillers, metal powders, colorants (pigments, dyes, etc.), foils, UV absorbers, antioxidants, light stabilizers, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, conductive agents, stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat stabilizers, polymerization inhibitors, lubricants, solvents, catalysts, and the like.

[0054] <Silicone-based adhesive> As the silicone-based adhesive, any suitable silicone-based adhesive can be used, such as a known silicone-based adhesive described in Japanese Patent Application Publication No. 2014-047280, as long as it does not impair the effects of the present invention. These may be one type or two or more types. The silicone-based adhesive may contain any suitable components, as long as it does not impair the effects of the present invention.

[0055] <Urethane-based adhesive> Urethane adhesives are formed from urethane adhesive compositions.

[0056] The urethane-based adhesive composition preferably comprises at least one selected from the group consisting of urethane prepolymers and polyols, and a crosslinking agent, in order to better exhibit the effects of the present invention.

[0057] At least one selected from the group consisting of urethane prepolymers and polyols can be referred to as a so-called base polymer in the field of urethane adhesives. The urethane prepolymer may be one type or two or more types. The polyol may be one type or two or more types.

[0058] [Urethane prepolymer] The urethane prepolymer is preferably a polyurethane polyol, and more preferably a polyester polyol (a1) or a polyether polyol (a2), either individually or as a mixture of (a1) and (a2), reacted with an organic polyisocyanate compound (a3) ​​in the presence or absence of a catalyst.

[0059] Any suitable polyester polyol (a1) can be used. Examples of such polyester polyols (a1) include polyester polyols obtained by reacting an acid component with a glycol component. Examples of acid components include terephthalic acid, adipic acid, azelaic acid, sebatic acid, phthalic anhydride, isophthalic acid, trimellitic acid, etc. Examples of glycol components include ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, 1,6-hexane glycol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, polyoxyethylene glycol, polyoxypropylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, and examples of polyol components include glycerin, trimethylolpropane, pentaerythritol, etc. Other examples of polyester polyols (a1) include polyester polyols obtained by ring-opening polymerization of lactones such as polycaprolactone, poly(β-methyl-γ-valerolactone), and polyvalerolactone.

[0060] The molecular weight of polyester polyol (a1) can range from low to high. Preferably, the number average molecular weight of polyester polyol (a1) is between 100 and 100,000, in order to better exhibit the effects of the present invention. If the number average molecular weight is less than 100, the reactivity will be high, and gelation may occur easily. If the number average molecular weight exceeds 100,000, the reactivity will be low, and furthermore, the cohesive force of the polyurethane polyol itself may decrease. Preferably, the amount of polyester polyol (a1) used is between 0 mol% and 90 mol% of the polyol constituting the polyurethane polyol, in order to better exhibit the effects of the present invention.

[0061] Any suitable polyether polyol (a2) can be used. Examples of such polyether polyols (a2) include those obtained by polymerizing oxirane compounds such as ethylene oxide, propylene oxide, butylene oxide, and tetrahydrofuran using a low molecular weight polyol such as water, propylene glycol, ethylene glycol, glycerin, or trimethylolpropane as an initiator. Specifically, examples of such polyether polyols (a2) include polyether polyols with two or more functional groups, such as polypropylene glycol, polyethylene glycol, and polytetramethylene glycol.

[0062] The polyether polyol (a2) can be used with a molecular weight ranging from low to high. Preferably, the number average molecular weight of the polyether polyol (a2) is between 100 and 100,000, in order to better exhibit the effects of the present invention. If the number average molecular weight is less than 100, the reactivity will be high, and gelation may occur easily. If the number average molecular weight exceeds 100,000, the reactivity will be low, and furthermore, the cohesive force of the polyurethane polyol itself may decrease. Preferably, the amount of polyether polyol (a2) used is between 0 mol% and 90 mol% of the polyol constituting the polyurethane polyol, in order to better exhibit the effects of the present invention.

[0063] Polyether polyol (a2) can be used in combination with glycols such as ethylene glycol, 1,4-butanediol, neopentyl glycol, butylethylpentanediol, glycerin, trimethylolpropane, and pentaerythritol, or polyhydric amines such as ethylenediamine, N-aminoethylethanolamine, isophoronediamine, and xylylenediamine, as needed.

[0064] As the polyether polyol (a2), only a bifunctional polyether polyol may be used, or a polyether polyol having a number average molecular weight of 100 to 100,000 and having at least three hydroxyl groups in one molecule may be used in part or in whole. When a polyether polyol having a number average molecular weight of 100 to 100,000 and having at least three hydroxyl groups in one molecule is used in part or in whole as the polyether polyol (a2), the effects of the present invention can be more fully expressed, and a good balance between adhesiveness and release properties can be achieved. In such polyether polyols, if the number average molecular weight is less than 100, the reactivity may increase, and gelation may become more likely. Also, in such polyether polyols, if the number average molecular weight exceeds 100,000, the reactivity may decrease, and furthermore, the cohesive force of the polyurethane polyol itself may decrease. The number average molecular weight of such polyether polyols is more preferably 100 to 10,000 in terms of being able to better express the effects of the present invention.

[0065] Any suitable organic polyisocyanate compound can be used as the organic polyisocyanate compound (a3). Examples of such organic polyisocyanate compounds (a3) ​​include aromatic polyisocyanates, aliphatic polyisocyanates, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates.

[0066] Examples of aromatic polyisocyanates include 1,3-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediisocyanate, 4,4'-diphenylmethanediisocyanate, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 4,4'-toluidinediisocyanate, 2,4,6-triisocyanatetoluene, 1,3,5-triisocyanatebenzene, dianisidinediisocyanate, 4,4'-diphenyletherdiisocyanate, and 4,4',4"-triphenylmethanetriisocyanate.

[0067] Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0068] Examples of aromatic aliphatic polyisocyanates include ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylenediisocyanate, and 1,3-tetramethylxylylenediisocyanate.

[0069] Examples of alicyclic polyisocyanates include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,4-bis(isocyanate methyl)cyclohexane, and 1,4-bis(isocyanate methyl)cyclohexane.

[0070] As the organic polyisocyanate compound (a3), trimethylolpropane adducts, biuret compounds obtained by reaction with water, and trimers having an isocyanurate ring can be used in combination.

[0071] Any suitable catalyst can be used to obtain polyurethane polyols. Examples of such catalysts include tertiary amine compounds and organometallic compounds.

[0072] Examples of tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabicyclo(5,4,0)-undecene-7(DBU).

[0073] Examples of organometallic compounds include tin compounds and non-tin compounds.

[0074] Examples of tin-based compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

[0075] Examples of non-tin compounds include titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate; iron compounds such as iron 2-ethylhexanoate and iron acetylacetonate; cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate; zinc compounds such as zinc naphthenate and zinc 2-ethylhexanoate; and zirconium compounds such as zirconium naphthenate.

[0076] When using a catalyst to obtain polyurethane polyols, systems containing two types of polyols, polyester polyols and polyether polyols, tend to exhibit problems such as gelation and turbidity of the reaction solution due to their differing reactivity when using a single catalyst. Therefore, using two types of catalysts when obtaining polyurethane polyols makes it easier to control the reaction rate and catalyst selectivity, thereby resolving these issues. Examples of such two-catalyst combinations include tertiary amine / organometallic, tin / non-tin, and tin / tin. Preferably, it is tin / tin, and more preferably a combination of dibutyltin dilaurate and tin 2-ethylhexanoate. The weight ratio of tin 2-ethylhexanoate / dibutyltin dilaurate is preferably less than 1, and more preferably 0.2 to 0.6. A ratio of 1 or more may increase the likelihood of gelation due to the balance of catalytic activity.

[0077] When a catalyst is used to obtain a polyurethane polyol, the amount of catalyst used is preferably 0.01% to 1.0% by weight relative to the total amount of polyester polyol (a1), polyether polyol (a2), and organic polyisocyanate compound (a3).

[0078] When a catalyst is used to obtain polyurethane polyols, the reaction temperature is preferably less than 100°C, and more preferably 85°C to 95°C. Above 100°C, it may become difficult to control the reaction rate and crosslinking structure, potentially making it difficult to obtain polyurethane polyols with a predetermined molecular weight.

[0079] A catalyst may not be used to obtain polyurethane polyols. In that case, the reaction temperature is preferably 100°C or higher, and more preferably 110°C or higher. Furthermore, when obtaining polyurethane polyols without a catalyst, it is preferable to allow the reaction to proceed for 3 hours or more.

[0080] Methods for obtaining polyurethane polyols include, for example, 1) a method of charging polyester polyol, polyether polyol, catalyst, and organic polyisocyanate into a volumetric flask, and 2) a method of charging polyester polyol, polyether polyol, and catalyst into a flask and then adding organic polyisocyanate. Method 2) is preferred for controlling the reaction when obtaining polyurethane polyols.

[0081] Any suitable solvent can be used to obtain polyurethane polyols. Examples of such solvents include methyl ethyl ketone, ethyl acetate, toluene, xylene, and acetone. Among these solvents, toluene is preferred.

[0082] [Polyol] Examples of polyols include, preferably, polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate polyols, and castor oil-based polyols. More preferably, the polyol is a polyether polyol.

[0083] Polyester polyols can be obtained, for example, by an esterification reaction between a polyol component and an acid component.

[0084] Examples of polyol components include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerin, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol. Examples of acidic components include succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanediic acid, 1,14-tetradecanediic acid, dimer acid, 2-methyl-1,4-cyclohexanedicarboxylic acid, 2-ethyl-1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-bifeldicarboxylic acid, and their acid anhydrides.

[0085] Examples of polyether polyols include those obtained by addition polymerization of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide, using water, low molecular weight polyols (propylene glycol, ethylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc.), bisphenols (bisphenol A, etc.), and dihydroxybenzenes (catechol, resorcinol, hydroquinone, etc.) as initiators. Specifically, examples include polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

[0086] Examples of polycaprolactone polyols include caprolactone-based polyester diols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and σ-valerolactone.

[0087] Examples of polycarbonate polyols include: polycarbonate polyols obtained by polycondensation reaction of the above polyol component with phosgene; polycarbonate polyols obtained by transesterification condensation of the above polyol component with diesters such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, ethylbutyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and dibenzyl carbonate; copolymerized polycarbonate polyols obtained by using two or more of the above polyol components in combination; polycarbonate polyols obtained by esterification reaction of the above various polycarbonate polyols with carboxyl group-containing compounds; and the above various poly Examples include: polycarbonate polyols obtained by etherification reaction of a polycarbonate polyol and a hydroxyl group-containing compound; polycarbonate polyols obtained by transesterification reaction of the above various polycarbonate polyols and ester compounds; polycarbonate polyols obtained by transesterification reaction of the above various polycarbonate polyols and hydroxyl group-containing compounds; polyester-based polycarbonate polyols obtained by polycondensation reaction of the above various polycarbonate polyols and dicarboxylic acid compounds; copolymerized polyether-based polycarbonate polyols obtained by copolymerization of the above various polycarbonate polyols and alkylene oxides; and so on.

[0088] Examples of castor oil-based polyols include those obtained by reacting castor oil fatty acids with the above-mentioned polyol components. Specifically, examples include castor oil-based polyols obtained by reacting castor oil fatty acids with polypropylene glycol.

[0089] The number-average molecular weight Mn of the polyol is preferably 300 to 100,000, more preferably 400 to 75,000, even more preferably 450 to 50,000, and particularly preferably 500 to 30,000, in order to better express the effects of the present invention.

[0090] The polyol preferably contains a polyol (A1) having three OH groups and a number-average molecular weight Mn of 300 to 100,000, in order to better express the effects of the present invention. Polyol (A1) may be one type or two or more types.

[0091] The content of polyol (A1) in the polyol is preferably 5% by weight or more, more preferably 25% to 100% by weight, and even more preferably 50% to 100% by weight, in order to better exhibit the effects of the present invention.

[0092] The number-average molecular weight Mn of the polyol (A1) is preferably 1,000 to 100,000, more preferably greater than 1,000 and 80,000 or less, even more preferably 1,100 to 70,000, even more preferably 1,200 to 60,000, even more preferably 1,300 to 50,000, even more preferably 1,400 to 40,000, even more preferably 1,500 to 35,000, particularly preferably 1,700 to 32,000, and most preferably 2,000 to 30,000, in terms of being able to better express the effects of the present invention.

[0093] The polyol may contain polyol (A2) having three or more OH groups and a number-average molecular weight Mn of 20,000 or less. Polyol (A2) may be of one type or two or more types. The number-average molecular weight Mn of polyol (A2) is preferably 100 to 20,000, more preferably 150 to 10,000, even more preferably 200 to 7,500, particularly preferably 300 to 6,000, and most preferably 300 to 5,000, in order to better express the effects of the present invention. As for polyol (A2), in order to better express the effects of the present invention, preferred examples include polyols having three OH groups (triol), polyols having four OH groups (tetraol), polyols having five OH groups (pentaol), and polyols having six OH groups (hexaol).

[0094] The total amount of polyol (A2) consisting of polyols having four OH groups (tetraol), polyols having five OH groups (pentaol), and polyols having six OH groups (hexaol) is preferably 70% by weight or less, more preferably 60% by weight or less, even more preferably 40% by weight or less, and particularly preferably 30% by weight or less, in order to better express the effects of the present invention.

[0095] The content of polyol (A2) in the polyol is preferably 95% by weight or less, and more preferably 0% to 75% by weight, in order to better exhibit the effects of the present invention.

[0096] The content of polyol (A2), which has four or more OH groups and a number-average molecular weight Mn of 20,000 or less, is preferably less than 70% by weight, more preferably 60% by weight or less, even more preferably 50% by weight or less, particularly preferably 40% by weight or less, and most preferably 30% by weight or less, relative to the total polyol, in order to better express the effects of the present invention.

[0097] [Crosslinking agent] The urethane-based adhesive composition preferably contains a crosslinking agent, as this allows for a more pronounced effect of the present invention.

[0098] Urethane prepolymers and polyols, used as base polymers, can be combined with crosslinking agents to form components of urethane-based adhesive compositions.

[0099] As a crosslinking agent to be combined with a urethane prepolymer and polyol as base polymers, a polyfunctional isocyanate-based crosslinking agent is preferred in that it can better exhibit the effects of the present invention.

[0100] As the polyfunctional isocyanate crosslinking agent, any suitable polyfunctional isocyanate crosslinking agent that can be used in the urethane reaction can be employed. Examples of such polyfunctional isocyanate crosslinking agents include the polyfunctional isocyanate crosslinking agents described in the above section on <acrylic adhesives>.

[0101] [Urethane-based adhesive composition] The urethane-based adhesive composition may contain any other suitable components as long as they do not impair the effects of the present invention. Examples of such other components include polymer components other than urethane prepolymers and polyols, crosslinking accelerators, crosslinking catalysts, silane coupling agents, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), anti-aging agents, inorganic fillers, organic fillers, metal powders, colorants (pigments, dyes, etc.), foil-like materials, degradation inhibitors, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, conductive agents, stabilizers, surface lubricants, leveling agents, corrosion inhibitors, heat-resistant stabilizers, polymerization inhibitors, lubricants, solvents, catalysts, and the like.

[0102] The urethane-based adhesive composition preferably contains a degradation inhibitor, as this allows for better expression of the effects of the present invention. The degradation inhibitor may be one type or two or more types.

[0103] Preferably, antioxidants, ultraviolet absorbers, and light stabilizers are used as degradation inhibitors, as they can better demonstrate the effects of the present invention.

[0104] Examples of antioxidants include radical chain inhibitors and peroxide decomposers.

[0105] Examples of radical chain inhibitors include phenolic antioxidants and amine-based antioxidants.

[0106] Examples of phenolic antioxidants include monophenolic antioxidants, bisphenolic antioxidants, and high molecular weight phenolic antioxidants. Examples of monophenolic antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stearin-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate. Examples of bisphenol-based antioxidants include 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), and 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane. Examples of high molecular weight phenolic antioxidants include 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-S-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol.

[0107] Examples of peroxide decomposing agents include sulfur-based antioxidants and phosphorus-based antioxidants. Examples of sulfur-based antioxidants include dilauryl 3,3'-thiodipropionate, dimyristyl 3,3'-thiodipropionate, and distearyl 3,3'-thiodipropionate. Examples of phosphorus-based antioxidants include triphenyl phosphite, diphenyl isodecyl phosphite, and phenyl diisodecyl phosphite.

[0108] Examples of UV absorbers include benzophenone-based UV absorbers, benzotriazole-based UV absorbers, salicylic acid-based UV absorbers, oxalic acid anilide-based UV absorbers, cyanoacrylate-based UV absorbers, and triazine-based UV absorbers.

[0109] Examples of benzophenone-based UV absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, and bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane.

[0110] Examples of benzotriazole-based UV absorbers include 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)5-chlorobenzotriazole, and 2-(2'-hydroxy Examples include -3',5'-di-tert-amylphenyl)benzotriazole, 2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, 2-[2'-hydroxy-3'-(3'',4'',5'',6'',-tetrahydrophthalimidomethyl)-5'-methylphenyl]benzotriazole, 2,2'methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol], and 2-(2'-hydroxy-5'-methacryloxyphenyl)-2H-benzotriazole.

[0111] Examples of salicylic acid-based UV absorbers include phenyl salicylate, p-tert-butylphenyl salicylate, and p-octylphenyl salicylate.

[0112] Examples of cyanoacrylate-based UV absorbers include 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate and ethyl-2-cyano-3,3'-diphenyl acrylate.

[0113] Examples of light stabilizers include hindered amine light stabilizers and ultraviolet light stabilizers. Examples of hindered amine light stabilizers include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, and methyl-1,2,2,6,6-pentamethyl-4-piperidyl sebacate. Examples of ultraviolet light stabilizers include nickel bis(octylphenyl) sulfide, [2,2'-thiobis(4-tert-octylphenolate)]-n-butylamine nickel, nickel complex-3,5-di-tert-butyl-4-hydroxybenzyl phosphate monoethylate, benzoate-type quenchers, and nickel-dibutyldithiocarbamate.

[0114] [A urethane polymer formed from a urethane adhesive composition containing a urethane prepolymer and a polyfunctional isocyanate crosslinking agent.] The urethane prepolymer may be of one type or two or more types. The polyfunctional isocyanate crosslinking agent may be of one type or two or more types.

[0115] As a method for forming a urethane polymer from a urethane adhesive composition containing a urethane prepolymer and a polyfunctional isocyanate crosslinking agent, any suitable manufacturing method can be adopted, as long as it uses a so-called "urethane prepolymer" as a raw material to produce the urethane polymer.

[0116] The number-average molecular weight (Mn) of the urethane prepolymer is preferably 3,000 to 1,000,000, in terms of enabling the effects of the present invention to be more fully realized.

[0117] In the urethane prepolymer and the polyfunctional isocyanate crosslinking agent, the equivalent ratio of NCO groups to OH groups is preferably 5.0 or less, more preferably 0.01 to 4.75, even more preferably 0.02 to 4.5, particularly preferably 0.03 to 4.25, and most preferably 0.05 to 4.0, in terms of the ability to better express the effects of the present invention.

[0118] The content ratio of the polyfunctional isocyanate crosslinking agent is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 25 parts by weight, even more preferably 0.1 to 20 parts by weight, particularly preferably 0.5 to 17.5 parts by weight, and most preferably 1 to 15 parts by weight, per 100 parts by weight of urethane prepolymer, in order to better express the effects of the present invention.

[0119] [A urethane polymer formed from a urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent.] The polyol may be one type or two or more types. The polyfunctional isocyanate crosslinking agent may be one type or two or more types.

[0120] In the polyol and polyfunctional isocyanate crosslinking agent, the equivalent ratio of NCO groups to OH groups is preferably 5.0 or less, more preferably 0.1 to 3.0, even more preferably 0.2 to 2.5, particularly preferably 0.3 to 2.25, and most preferably 0.5 to 2.0, in order to better express the effects of the present invention.

[0121] The content ratio of the polyfunctional isocyanate crosslinking agent is preferably 1.0 to 30 parts by weight, more preferably 1.5 to 27 parts by weight, even more preferably 2.0 to 25 parts by weight, particularly preferably 2.3 to 23 parts by weight, and most preferably 2.5 to 20 parts by weight per 100 parts by weight of polyol, in order to better express the effects of the present invention.

[0122] The urethane polymer formed from a urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent is, more specifically, preferably, formed by curing the urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent. Any suitable method can be used to form the urethane polymer by curing the urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent, such as urethane polymerization reaction methods using bulk polymerization or solution polymerization, as long as the effects of the present invention are not impaired.

[0123] A catalyst is preferably used to cure a urethane adhesive composition containing a polyol and a polyfunctional isocyanate crosslinking agent. Examples of such catalysts include organometallic compounds and tertiary amine compounds.

[0124] Examples of organometallic compounds include iron-based compounds, tin-based compounds, titanium-based compounds, zirconium-based compounds, lead-based compounds, cobalt-based compounds, and zinc-based compounds. Among these, iron-based compounds and tin-based compounds are preferred in terms of reaction rate and the pot life of the adhesive layer.

[0125] Examples of iron-based compounds include iron acetylacetonate, iron 2-ethylhexanoate, and ferric narsem.

[0126] Examples of tin-based compounds include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin maleate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin sulfide, tributyltin methoxide, tributyltin acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, dioctyltin dilaurate, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate.

[0127] Examples of titanium-based compounds include dibutyltitanium dichloride, tetrabutyltitanate, and butoxytitanium trichloride.

[0128] Examples of zirconium-based compounds include zirconium naphthenate and zirconium acetylacetonate.

[0129] Examples of lead-based compounds include lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate.

[0130] Examples of cobalt-based compounds include cobalt 2-ethylhexanoate and cobalt benzoate.

[0131] Examples of zinc-based compounds include zinc naphthenate and zinc 2-ethylhexanoate.

[0132] Examples of tertiary amine compounds include triethylamine, triethylenediamine, and 1,8-diazabicyclic-(5,4,0)-undecene-7.

[0133] The catalyst may be of one type only, or of two or more types. Furthermore, the catalyst may be used in combination with a crosslinking retarder or the like. The amount of catalyst is preferably 0.005 to 1.00 parts by weight, more preferably 0.01 to 0.75 parts by weight, even more preferably 0.01 to 0.50 parts by weight, and particularly preferably 0.01 to 0.20 parts by weight, per 100 parts by weight of polyol, in order to better exhibit the effects of the present invention.

[0134] ≪1-2. Adhesive Treatment Solution≫ The adhesive treatment liquid used in the embodiments of the present invention comprises a liquid having a Hansen solubility parameter value of 31 or less and an alkaline compound, wherein the concentration of the alkaline compound is 0.001% to 20% by weight.

[0135] In this invention, "liquid" refers to a substance that is liquid at room temperature and pressure, and generally includes water, alcohol, and various other solvents.

[0136] The liquid in the adhesive treatment solution having a Hansen solubility parameter value of 31 or less may be just one type or two or more types.

[0137] The alkaline compound in the adhesive treatment solution may be one type or two or more types.

[0138] The adhesive treatment solution contains a liquid with a Hansen solubility parameter value of 31 or less and an alkaline compound, and the concentration of the alkaline compound is between 0.01% and 10% by weight, which allows for the smooth production of water-soluble polymers from adhesives under mild conditions.

[0139] The "Hansen solubility parameter value" is the Hildebrand solubility parameter value with a dispersion term (δ D ), polarity term (δ p ), and hydrogen bond term (δ HThe HSP value is a parameter value that takes into account the polarity of a substance and is divided into three components. The dispersion term (term related to van der Waals forces), the polarity term (term related to dipole moments), and the hydrogen bonding term (term related to hydrogen bonds) can be represented in three-dimensional coordinates.

[0140] The Hansen solubility parameter value of a mixture of two or more liquids can be determined as the weighted average value m of the HSP values ​​of each solvent using the following formula (1). Here, δ1 and δ2 are the HSP values ​​of each liquid component, and φ1 and φ2 are the volume fractions of each liquid component. m = δ1φ1 + δ2φ2···(1)

[0141] The Hansen solubility parameter values ​​for each solvent are included in "HSPiP Version 5," and for solvents not included, the values ​​estimated by "HSPiP Version 5" are used.

[0142] The Hansen solubility parameter value of the liquid contained in the adhesive treatment solution is 31 or less, preferably 30 or less, more preferably 29 or less, even more preferably 28 or less, and particularly preferably 25 or less. The lower limit of the Hansen solubility parameter value of the liquid contained in the adhesive treatment solution is preferably 7 or more, more preferably 10 or more, even more preferably 13 or more, and particularly preferably 15 or more. If the Hansen solubility parameter value of the liquid contained in the adhesive treatment solution is within the above range, preferably 10 to 30, and more preferably 15 to 25, then a water-soluble polymer can be stably produced from the adhesive under mild conditions.

[0143] If the Hansen solubility parameter value of the liquid contained in the adhesive treatment solution exceeds 31, the penetration of the adhesive treatment solution into the adhesive may deteriorate, potentially reducing the production efficiency of water-soluble polymers. Similarly, if the Hansen solubility parameter value of the liquid contained in the adhesive treatment solution falls below 7, although not to the same extent as when it exceeds 31, the penetration of the adhesive treatment solution into the adhesive may deteriorate, potentially reducing the production efficiency of water-soluble polymers.

[0144] Typical examples of liquids included in adhesive treatment solutions that have a Hansen solubility parameter value of 31 or less as a single liquid include the following: Alcohols: Methanol (HSP value = 29.6), Ethanol (HSP value = 26.5), 1-Propanol (HSP value = 24.6), 2-Propanol (IPA) (HSP value = 23.6), 1-Butanol (HSP value = 23.2), 1-Pentanol (HSP value = 21.7), 1-Hexanol (HSP value = 21.2), Benzyl alcohol (HSP value = 23.8), Diethylene glycol (HSP value = 27.9), Dipropylene glycol (HSP value = 26.4) Hydrocarbons; benzene (HSP value = 18.5), toluene (HSP value = 18.2), styrene (HSP value = 19.1), hexane (HSP value = 14.9), cyclohexane (HSP value = 16.8), heptane (HSP value = 15.3) Ketones; acetone (HSP value = 19.9), methyl ethyl ketone (HSP value = 19.1) Esters; ethyl acetate (HSP value = 18.2) Ethers; tetrahydrofuran (HSP value = 19.5), cyclopentyl methyl ether (HSP value = 17.8) Amines; Aniline (HSP value = 23.7) Nitriles; Acetonitrile (HSP value = 24.4) Carboxylic acids; Acetic acid (HSP value = 21.4) Terpenes; d-limonene (HSP value = 17.8)

[0145] These liquids may be used individually or in combination of two or more. In addition to liquids whose Hansen solubility parameter as a single liquid is 31 or less, any mixed liquid can be used as long as the Hansen solubility parameter value of the mixed liquid, as calculated by formula (1) above, is 31 or less. An example of a solvent that can be used as a mixed liquid by combining multiple liquids is water (HSP value = 47.8). For example, if water (HSP value = 47.8) and ethanol (HSP value = 26.5) are used in a volume fraction of water / ethanol = 20% / 80%, then m = 30.76, and it can be used.

[0146] Liquids with a Hansen solubility parameter value of 31 or less preferably contain alcohols, and more preferably lower alcohols, from the viewpoint of solubility of alkaline compounds. Lower alcohols may include not only primary alcohols, but also secondary alcohols such as 2-propanol, propylene glycol monopropyl ether, and propylene glycol monoethyl ether, and tertiary alcohols such as t-butyl alcohol.

[0147] The lower alcohol preferably includes a lower alcohol having 1 to 5 carbon atoms (typically, at least one selected from methanol, ethanol, 1-propanol, 2-propanol, butanol, and 1-pentanol), more preferably a lower alcohol having 1 to 4 carbon atoms (typically, at least one selected from methanol, ethanol, 1-propanol, 2-propanol, and butanol), even more preferably a lower alcohol having 1 to 3 carbon atoms (typically, at least one selected from methanol, ethanol, 1-propanol, and 2-propanol), and particularly preferably a lower alcohol having 1 to 2 carbon atoms (at least one selected from methanol and ethanol).

[0148] Liquids with a Hansen solubility parameter value of 31 or less preferably contain alcohols in addition to organic solvents other than alcohols. The organic solvents other than alcohols may be used individually or in combination of two or more. Examples of organic solvents other than alcohols are the ethers and hydrocarbons mentioned above, preferably at least one selected from toluene, cyclopentyl methyl ether, and tetrahydrofuran, and more preferably at least one selected from toluene and cyclopentyl methyl ether. When the liquid with a Hansen solubility parameter value of 31 or less is a mixed solvent of alcohols and an organic solvent (preferably at least one selected from ethers and hydrocarbons), the permeability of the adhesive treatment solution to the adhesive can be improved, and the production efficiency of water-soluble polymers can be improved.

[0149] When a liquid with a Hansen solubility parameter value of 31 or less contains alcohols and an organic solvent other than alcohols (preferably at least one selected from ethers and hydrocarbons), the volume ratio of the organic solvent to the alcohols (organic solvent:alcohols) is preferably 10:90 to 99:1, more preferably 20:80 to 95:5, even more preferably 30:70 to 90:10, particularly preferably 40:60 to 90:10, and most preferably 60:40 to 80:20. If the volume ratio of the organic solvent to the alcohols is within the above range, the permeability of the adhesive treatment liquid to the adhesive can be further improved, and the efficiency of water-soluble polymer production can be stably improved.

[0150] The alkali compound contained in the adhesive treatment liquid can be any suitable alkali compound as long as it does not impair the effects of the present invention. Examples of such alkali compounds include hydroxides and carbonates of alkali metals or alkaline earth metals, such as potassium hydroxide, sodium hydroxide, and calcium hydroxide, as well as metal alkoxides such as sodium methoxide, sodium ethoxide, and potassium t-butoxide. Preferably, it is at least one selected from the group consisting of potassium hydroxide, sodium hydroxide, and sodium ethoxide.

[0151] The concentration of the alkali compound in the adhesive treatment solution is preferably 0.001% to 20% by weight, more preferably 0.01% to 10% by weight, even more preferably 0.01% to 8% by weight, particularly preferably 0.01% to 5% by weight, and most preferably 0.5% to 1.5% by weight. If the concentration of the alkali compound in the adhesive treatment solution is within the above range, water-soluble polymers can be produced more stably from the adhesive under mild conditions. If the concentration of the alkali compound in the adhesive treatment solution exceeds 20% by weight, the alkali compound becomes less soluble in the treatment solvent (a liquid with a Hansen solubility parameter value of 31 or less), and in the case of adhesive tape, it may adversely affect not only the adhesive but also the substrate.

[0152] The adhesive treatment solution may contain other additives. Any suitable additive can be used as the other additive, as long as it does not impair the effects of the present invention. Examples of such additives include various known additives such as ionic surfactants, nonionic surfactants, chelating agents, solubilizers, slurrying agents, and defoaming agents.

[0153] ≪1-3. Adhesive Treatment Process≫ In the method for producing a water-soluble polymer according to an embodiment of the present invention, typically the above-mentioned adhesive is impregnated with the above-mentioned adhesive treatment solution. This allows for the smooth production of a water-soluble polymer from the adhesive under mild conditions.

[0154] As for the method of impregnating the adhesive with the adhesive treatment solution, any appropriate impregnation method can be appropriately adopted depending on the type of scale and adhesive. In this specification, "impregnating the adhesive with the adhesive treatment solution" means bringing the adhesive into a state in which the adhesive treatment solution is impregnated, for example, by bringing the adhesive into a state in which at least a portion of it is immersed in the adhesive treatment solution. This is because if at least a portion of the adhesive is immersed in the adhesive treatment solution, the adhesive treatment solution will seep into the adhesive.

[0155] In a method for producing a water-soluble polymer according to an embodiment of the present invention, one preferred embodiment involves stirring the adhesive while it is impregnated with an adhesive treatment solution. By stirring the adhesive while it is impregnated with the adhesive treatment solution, a water-soluble polymer can be produced more smoothly from the adhesive. In this specification, "a state in which the adhesive is impregnated with the adhesive treatment solution" refers to a state in which the adhesive is impregnated with the adhesive treatment solution, for example, a state in which at least a portion of the adhesive is immersed in the adhesive treatment solution. This is because if at least a portion of the adhesive is immersed in the adhesive treatment solution, the adhesive treatment solution will seep into the adhesive.

[0156] As for the stirring method, any appropriate stirring method can be appropriately adopted depending on the type of scale and adhesive.

[0157] In an adhesive treatment method according to an embodiment of the present invention, one preferred embodiment involves ultrasonic treatment while the adhesive is impregnated with an adhesive treatment solution. By performing ultrasonic treatment while the adhesive is impregnated with an adhesive treatment solution, a water-soluble polymer can be produced from the adhesive more smoothly.

[0158] As for the ultrasonic treatment method, any appropriate ultrasonic treatment method can be appropriately adopted depending on the type of scale or adhesive.

[0159] In a method for producing a water-soluble polymer according to an embodiment of the present invention, in one preferred embodiment, the temperature of the adhesive impregnated with the adhesive treatment solution is preferably 20°C or higher, more preferably 25°C or higher, even more preferably 30°C or higher, even more preferably 35°C or higher, even more preferably 40°C or higher, particularly preferably 45°C or higher, with an upper limit of preferably 120°C or lower, more preferably 100°C or lower, and even more preferably 80°C or lower. If the temperature of the adhesive impregnated with the adhesive treatment solution is within the above range, a water-soluble polymer can be smoothly produced from the adhesive in a simple manner under mild conditions.

[0160] In a method for producing a water-soluble polymer according to an embodiment of the present invention, another preferred embodiment involves producing a water-soluble polymer from the adhesive of an adhesive tape containing a substrate and an adhesive. More specifically, a physical method can also be applied as a method for separating the substrate and adhesive from the adhesive tape. Specifically, the adhesive is scraped off from the adhesive tape using an abrasive cloth, abrasive belt, abrasive paper, abrasive brush, etc., to separate the substrate and the adhesive. The separated adhesive is then impregnated with an adhesive treatment solution.

[0161] According to the method for producing a water-soluble polymer according to an embodiment of the present invention, the adhesive swells in the adhesive treatment solution, and hydrolysis (including saponification reactions in which salts and alcohols are produced by the reaction of an ester and a base) proceeds with an alkali compound and a liquid containing a Hansen solubility parameter value of 31 or less in the adhesive treatment solution. By causing the reaction to proceed mainly through saponification, a water-soluble polymer can be produced efficiently. Since the activation energy required for saponification is higher than that of the transesterification reaction, the reaction can be appropriately controlled by carrying out the reaction at a temperature within the above range (preferably 20°C to 120°C). As a result, a water-soluble polymer is formed from the adhesive and dissolved or dispersed in the adhesive treatment solution according to an embodiment of the present invention. Such a water-soluble polymer derived from the adhesive can be recovered as a solution or dispersion by further treatment with a solvent as needed, and in a preferred embodiment, it can be recovered as a solution in which the water-soluble polymer is dissolved in an aqueous solvent. Examples of aqueous solvents include water, alcohol, mixed solvents thereof, and mixed solvents of these with organic solvents. Here, "water-soluble polymer derived from adhesive" means a water-soluble polymer having a structure derived from the main polymer (also called the base polymer) used in the composition of the adhesive. Specifically, for example, it means a water-soluble polymer having a structure in which at least some of the functional groups (e.g., carboxyl groups or ester groups) present at the side chain ends of the main polymer (sometimes called the base polymer) that constitutes the adhesive have undergone hydrolysis (including saponification reactions in which salts and alcohols are produced by the reaction of esters and bases) by an alkali compound with a Hansen solubility parameter value of 31 or less contained in the adhesive treatment solution.

[0162] According to the method for producing a water-soluble polymer according to the embodiment of the present invention, a water-soluble polymer can be easily obtained from an adhesive under mild conditions. This is presumed to be because, according to the method for producing a water-soluble polymer according to the embodiment of the present invention, the hydrolysis of the adhesive (including a saponification reaction in which a salt and an alcohol are produced by the reaction of an ester and a base) proceeds easily under mild conditions, and as a result, a water-soluble polymer is obtained.

[0163] Conventionally, in order to perform hydrolysis of an adhesive (including saponification reaction in which salt and alcohol are produced by the reaction of an ester and a base), it is necessary to perform the above reaction under conditions of high temperature and high pressure, or to design the composition of the adhesive to a limited composition. According to the method for producing a water-soluble polymer according to an embodiment of the present invention, good hydrolysis of the adhesive (including saponification reaction in which salt and alcohol are produced by the reaction of an ester and a base) can be easily performed under mild conditions without setting conditions of high temperature and high pressure and without designing the composition of the adhesive to a limited composition.

[0164] ≪≪2. Water-soluble polymer≫≫ The water-soluble polymer obtained by the method for producing a water-soluble polymer according to an embodiment of the present invention typically includes a structural unit (1) represented by the following formula and a structural unit (2) represented by the following formula.

Chemical formula

[0165] The water-soluble polymer typically contains a plurality of each of the structural unit (1) and the structural unit (2). In the molecular chain of the water-soluble polymer, the structural unit (1) and the structural unit (2) are typically arranged randomly.

[0166] In the structural unit (1) and the structural unit (2), R 1 represents a hydrogen atom or a methyl group, preferably a hydrogen atom. In a plurality of the structural units (1), R 1 may be the same as or different from each other. In the structural unit (1) and the structural unit (2), R 1These components may be identical or different from each other. The presence of component (1) in the water-soluble polymer lowers the glass transition temperature of the water-soluble polymer, improving its flexibility at room temperature. The presence of component (2) in the water-soluble polymer makes it soluble in water. The presence of component (1) and (2) in the water-soluble polymer makes it a suitable raw material for an excellent water-soluble adhesive.

[0167] In constituent unit (1), R 2 The alkyl group represented by is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably a methyl group, an ethyl group, an n-butyl group, and a 2-ethylhexyl group. In the multiple constituent units (1), 2 They may be identical to each other or they may be different to each other.

[0168] In the constituent unit (2), the cation represented by M is preferably an alkali metal cation or an alkaline earth metal cation, more preferably an alkali metal cation, and even more preferably a potassium cation or a sodium cation. In multiple constituent units (2), M may be the same as or different from each other.

[0169] The content of constituent unit (1) in the water-soluble polymer is preferably 1% by weight or more, more preferably 3% by weight or more, even more preferably 5% by weight or more, and particularly preferably 10% by weight or more. The upper limit is preferably 95% by weight or less, more preferably 90% by weight or less, even more preferably 85% by weight or less, and particularly preferably 80% by weight or less.

[0170] The content of constituent unit (2) in the water-soluble polymer is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, and particularly preferably 20% by weight or more. The upper limit is preferably 95% by weight or less, more preferably 90% by weight or less, even more preferably 87% by weight or less, and particularly preferably 85% by weight or less.

[0171] The content ratio of component unit (1) to the total sum of component unit (1) and component unit (2) is preferably 5% by weight or more, more preferably 7% by weight or more, even more preferably 10% by weight or more, and the upper limit is preferably 95% by weight or less, more preferably 90% by weight or less, even more preferably 93% by weight or less, and particularly preferably 90% by weight or less.

[0172] The proportion of constituent units can be measured, for example, by FT-IR, NMR, or titration.

[0173] The water-soluble polymer according to the embodiments of the present invention can be appropriately used as a raw material for various industrial products. The water-soluble polymer according to the embodiments of the present invention can be suitably used as a raw material for adhesives or as a raw material for water-absorbent polymers.

[0174] ≪≪3. Method for producing superabsorbent polymers≫≫ Examples of methods for producing a superabsorbent polymer according to embodiments of the present invention include a method for producing a superabsorbent polymer using a water-soluble polymer obtained by a method for producing a water-soluble polymer according to embodiments of the present invention (hereinafter sometimes referred to as "production method A"), and a method for producing a superabsorbent polymer directly from adhesive waste (hereinafter sometimes referred to as "production method B").

[0175] ≪3-1. Manufacturing method A≫ In a method for producing a water-absorbent polymer according to one embodiment of the present invention, a water-soluble polymer obtained by a method for producing a water-soluble polymer according to an embodiment of the present invention is reacted with a crosslinking agent. By reacting the water-soluble polymer with the crosslinking agent, water-absorbing properties can be imparted to the polymer.

[0176] The crosslinking agent is an internal crosslinking agent that can react with the constituent units of the water-soluble polymer. The amount of crosslinking agent used is preferably 0.1 to 200 parts by weight, more preferably 1 to 150 parts by weight, and even more preferably 1 to 100 parts by weight, per 100 parts by weight of the water-soluble polymer.

[0177] Examples of crosslinking agents include polymerizable crosslinking agents, reactive crosslinking agents, and crosslinking agents that combine both.

[0178] Polymerizable crosslinking agents can react with ethylenically unsaturated double bonds contained in water-soluble polymers. Specific examples of polymerizable crosslinking agents include compounds having at least two polymerizable double bonds within their molecules, such as N,N'-methylenebisacrylamide, (poly)ethylene glycol di(meth)acrylate, (polyoxyethylene)trimethylolpropane tri(meth)acrylate, and poly(meth)alyloxyalkanes.

[0179] Reactive crosslinking agents can react with carboxyl groups (more specifically, the -COOM groups in the above-mentioned structural unit (2)) contained in water-soluble polymers. Specific examples of reactive crosslinking agents include, for example, covalent crosslinking agents such as polyglycidyl ethers (ethylene glycol diglycidyl ether, etc.) and polyhydric alcohols (ethylene glycol, polyethylene glycol, propanediol, glycerin, sorbitol, etc.), ionic crosslinking agents which are polyvalent metal compounds such as aluminum, melamine resin-based crosslinking agents, amino resin-based crosslinking agents, peroxide-based crosslinking agents, and the aforementioned polyfunctional isocyanate-based crosslinking agents.

[0180] The crosslinking agent may be used alone or in combination of two or more types.

[0181] Preferably, the crosslinking agent is a reactive crosslinking agent, and more preferably, ethylene glycol or polyethylene glycol.

[0182] In one embodiment of the present invention, method A for producing a water-absorbent polymer, a crosslinking agent is typically added to a solution (or dispersion) of a water-soluble polymer.

[0183] In one preferred embodiment, a crosslinking agent is added to a solution (or dispersion) of a water-soluble polymer, and then the mixture is stirred. Any suitable stirring method can be appropriately employed.

[0184] In one preferred embodiment, a water-soluble polymer and a crosslinking agent are reacted in the aforementioned adhesive treatment solution (a liquid with a Hansen solubility parameter value of 31 or less and an alkaline compound, wherein the concentration of the alkaline compound is 0.001% to 20% by weight). This allows the polymer and the crosslinking agent to react while further hydrolysis (including saponification) of the water-soluble polymer, enabling the smooth production of a water-absorbent polymer.

[0185] The adhesive treatment solution (hereinafter referred to as the treatment solution for producing superabsorbent polymers) preferably contains 1% to 90% by volume, more preferably 1% to 80% by volume, even more preferably 1% to 70% by volume, even more preferably 1% to 60% by volume, particularly preferably 1% to 50% by volume, and most preferably 1% to 40% by volume of alcohols. When the adhesive treatment solution contains alcohols, the saponification reaction and the transesterification reaction of the alcohols can be carried out in the production of the superabsorbent polymer, and the reactivity of the polymer to the crosslinking agent can be suitably adjusted.

[0186] Preferably, the treatment solution for producing superabsorbent polymers has a Hansen solubility parameter value of 10 or more and 29 or less, and an alkali compound concentration of 0.01% by weight or more and 8% by weight or less. More preferably, the Hansen solubility parameter value of the liquid has a Hansen solubility parameter value of 13 or more and 25 or less, and an alkali compound concentration of 0.5% by weight or more and 5% by weight or less. When the Hansen solubility parameter value of the liquid and / or the alkali compound concentration are both within the above ranges in the treatment solution for producing superabsorbent polymers, the saponification reaction and the transesterification reaction can proceed in a balanced manner, and superabsorbent polymers can be produced stably. If the Hansen solubility parameter value of the liquid and / or the alkali compound concentration are outside the above ranges, the saponification reaction may become excessively dominant over the transesterification reaction. In this case, the reaction between the crosslinking agent and the polymer (or adhesive) may converge at the surface of the polymer (or adhesive), and it may not be possible to produce superabsorbent polymers.

[0187] In one preferred embodiment, the temperature during the reaction of the water-soluble polymer and the crosslinking agent in the adhesive treatment solution is preferably 15°C or higher, more preferably 20°C or higher, even more preferably 25°C or higher, even more preferably 30°C or higher, particularly preferably 35°C or higher, most preferably 40°C or higher, with an upper limit of preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 60°C or lower. If the temperature during the reaction of the water-soluble polymer and the crosslinking agent in the adhesive treatment solution is within the above range, a water-absorbent polymer can be smoothly produced from the water-soluble polymer and the crosslinking agent under mild conditions. By causing the reaction to proceed mainly through transesterification, a water-absorbent polymer can be produced efficiently. Since the activation energy required for the transesterification reaction is lower than that for saponification, the reaction can be appropriately controlled by carrying out the reaction at the above temperature range (preferably 15°C to 80°C).

[0188] According to one embodiment of the present invention, a method for producing a superabsorbent polymer, A, a superabsorbent polymer can be easily obtained from adhesive waste via a water-soluble polymer under mild conditions. This is presumed to be because, according to one embodiment of the present invention, a method for producing a superabsorbent polymer, A, the water-soluble polymer (particularly the -COOM group in constituent unit (2)) and the crosslinking agent proceed easily under mild conditions, resulting in the acquisition of a superabsorbent polymer.

[0189] ≪3-2. Manufacturing method B≫ Another embodiment of the present invention provides a method for producing a water-absorbent polymer, method B, which involves contacting the aforementioned adhesive treatment solution (an adhesive treatment solution containing a liquid with a Hansen solubility parameter value of 31 or less and an alkaline compound, wherein the concentration of the alkaline compound is 0.001% to 20% by weight) with a crosslinking agent and an adhesive.

[0190] As for the contact method between the adhesive treatment liquid, the crosslinking agent, and the adhesive, any appropriate contact method can be adopted as long as it does not impair the effects of the present invention. Examples of such contact methods include adding the crosslinking agent to the adhesive treatment liquid, then adding the adhesive and bringing them into contact; adding the crosslinking agent and the adhesive simultaneously to the adhesive treatment liquid and bringing them into contact; and adding the adhesive to the adhesive treatment liquid, then adding the crosslinking agent and bringing them into contact.

[0191] According to manufacturing method B described above, a superabsorbent polymer can be easily obtained directly from adhesive waste under mild conditions.

[0192] In this method B for producing superabsorbent polymers, the above-described treatment liquid for producing superabsorbent polymers is preferably used as the adhesive treatment liquid.

[0193] The amount of crosslinking agent added is preferably 0.1 to 200 parts by weight, more preferably 1 to 150 parts by weight, and even more preferably 1 to 100 parts by weight, per 100 parts by weight of the adhesive.

[0194] The temperature range during contact between the adhesive treatment solution, the crosslinking agent, and the adhesive is, for example, the same as the temperature range during the reaction between the water-soluble polymer and the crosslinking agent in the adhesive treatment solution.

[0195] Thus, according to manufacturing method B, a superabsorbent polymer can be easily obtained from an adhesive under mild conditions. This is presumed to be because the hydrolysis of the adhesive (including the saponification reaction in which a salt and an alcohol are produced by the reaction of an ester and a base) proceeds easily under mild conditions, and the reaction between the carboxyl group (more specifically the -COOM group in the above constituent unit (2)) and the crosslinking agent proceeds to obtain a superabsorbent polymer.

[0196] ≪≪4. Superabsorbent Polymer≫≫ The superabsorbent polymer according to embodiments of the present invention typically includes a constituent unit (1) represented by the following formula, a constituent unit (2) represented by the following formula, and a crosslinked structure formed by the reaction of the constituent unit (1) and / or the constituent unit (2) represented by the following formula with the crosslinking agent described above. The crosslinked structure is preferably formed by the reaction of the constituent unit (2) represented by the following formula with the crosslinking agent described above. [ka] (In the formula, R 1 R represents a hydrogen atom or a methyl group. 2 (where M represents an alkyl group with 1 to 12 carbon atoms, and M represents a hydrogen atom or cation.)

[0197] In constituent unit (1) and constituent unit (2), R 1 , R 2 Regarding M, in the constituent units (1) and (2) of the water-soluble polymer described above, R 1 , R 2 We can use M's explanation as a basis.

[0198] The proportion of constituent unit (1) in the superabsorbent polymer can be determined by referring to the explanation of the proportion of constituent unit (1) in the water-soluble polymer described above.

[0199] The range of the sum of the content ratios of constituent units (2) and crosslinked structures in the water-absorbent polymer can be explained by referring to the above-described explanation of the range of content ratios of constituent units (2) in water-soluble polymers.

[0200] The content of the cross-linked structure in the water-absorbent polymer is preferably 1% by weight or more, more preferably 3% by weight or more, even more preferably 5% by weight or more, and particularly preferably 7% by weight or more. The upper limit is preferably 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less, and particularly preferably 75% by weight or less.

[0201] The content ratio of component unit (1) to the total sum of component unit (1) and component unit (2) is preferably 3% by weight or more, more preferably 5% by weight or more, even more preferably 7% by weight or more, and particularly preferably 10% by weight or more. The upper limit is preferably 95% by weight or less, more preferably 90% by weight or less, even more preferably 85% by weight or less, and particularly preferably 80% by weight or less.

[0202] The superabsorbent polymer according to the embodiments of the present invention can be obtained by any suitable method, provided that the effects of the present invention are not impaired. Such a method is, for example, a method for producing the superabsorbent polymer according to the embodiments of the present invention. [Examples]

[0203] The present invention will be specifically described below with reference to examples, but the present invention is not limited in any way to these examples. The test and evaluation methods in the examples are as follows. When "parts" is written, it means "parts by weight" unless otherwise specified, and when "%" is written, it means "percent by weight" unless otherwise specified.

[0204] <Preparing the adhesive tape> I prepared the following adhesive tapes. "E-MASK" series (manufactured by Nitto Denko Corporation), part number RP108C, acrylic adhesive. "E-MASK" series (manufactured by Nitto Denko Corporation), part number RP207, acrylic adhesive. "Riva Alpha" series (manufactured by Nitto Denko Corporation), part number No. 3195MS(N), acrylic adhesive. Floor protection tape (manufactured by Nitto Denko Corporation), product number No. 395N, acrylic adhesive. "Nitoflon" series (manufactured by Nitto Denko Corporation), part number No. 973UL, silicone-based adhesive.

[0205] <Preparation of adhesive treatment solution> [Preparation Example 1] Potassium hydroxide (KOH) was added to 1-butanol (HSP value = 23.2) to obtain adhesive treatment solution (1) with an alkali concentration of 0.5% by volume. The results are summarized in Table 1.

[0206] [Preparation Example 2] To a mixed solvent of cyclopentyl methyl ether (Cpme) / methanol = 70 / 30 (volume ratio) (HSP value = 20.0), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (2) so that the alkali concentration in the resulting treatment solution was 1.3% by weight. The results are summarized in Table 1.

[0207] [Preparation Example 3] To a mixed solvent of cyclopentyl methyl ether (Cpme) / ethanol = 70 / 30 (volume ratio) (HSP value = 19.5), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (3) so that the alkali concentration in the resulting treatment solution was 1.3% by weight. The results are summarized in Table 1.

[0208] [Preparation Example 4] To a mixed solvent of cyclopentyl methyl ether (Cpme) / 2-propanol (IPA) = 70 / 30 (volume ratio) (HSP value = 18.9), potassium hydroxide (KOH) was added to obtain a tackening treatment solution (4) so ​​that the alkali concentration in the resulting treatment solution was 1.3% by weight. The results are summarized in Table 1.

[0209] [Preparation Example 5] To a mixed solvent of cyclopentyl methyl ether (Cpme) / 1-butanol = 70 / 30 (volume ratio) (HSP value = 18.8), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (5) so that the alkali concentration in the resulting treatment solution was 1.3% by weight. The results are summarized in Table 1.

[0210] [Preparation Example 6] To a mixed solvent of cyclopentyl methyl ether (Cpme) / benzyl alcohol = 70 / 30 (volume ratio) (HSP value = 18.7), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (6) so that the alkali concentration in the resulting treatment solution was 1.3% by weight. The results are summarized in Table 1.

[0211] [Preparation Example 7] Potassium hydroxide (KOH) was added to a toluene / methanol mixed solvent of 80 / 20 (volume ratio) (HSP value = 18.7) to obtain a tackifying agent treatment solution (7) with an alkali concentration of 1.0% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0212] [Preparation Example 8] To a mixed solvent of toluene / 1-butanol = 80 / 20 (volume ratio) (HSP value = 18.4), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (8) so that the alkali concentration in the resulting treatment solution was 1.0% by weight. The results are summarized in Table 1.

[0213] [Preparation Example 9] Sodium ethoxide (NaOEt) was added to a mixed solvent of ethanol / 1-butanol = 50 / 50 (volume ratio) (HSP value = 24.8) to obtain a tackifying agent treatment solution (9) with an alkali concentration of 5.0% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0214] [Preparation Example 10] To a mixed solvent of heptane / echinae® (F-6, manufactured by Nippon Alcohol Sales Co., Ltd.) = 95 / 5 (volume ratio) (HSP value = 15.3), potassium hydroxide (KOH) was added to obtain a tackening treatment solution (10) so that the alkali concentration in the resulting treatment solution was 2.0% by weight. The results are summarized in Table 1.

[0215] [Preparation Example 11] To a mixed solvent of heptane / echinae® (F-6, manufactured by Nippon Alcohol Sales Co., Ltd.) = 90 / 10 (volume ratio) (HSP value = 15.5), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (11) so that the alkali concentration in the resulting treatment solution was 2.0% by weight. The results are summarized in Table 1.

[0216] [Preparation Example 12] To a mixed solvent of cyclopentyl methyl ether (Cpme) / methanol = 50 / 50 (volume ratio) (HSP value = 17.7), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (12) so that the alkali concentration in the resulting treatment solution was 10% by weight. The results are summarized in Table 1.

[0217] [Preparation Example 13] To a mixed solvent of cyclopentyl methyl ether (Cpme) / methanol = 50 / 50 (volume ratio) (HSP value = 17.7), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (13) with an alkali concentration of 14% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0218] [Preparation Example 14] To a mixed solvent of methyl ethyl ketone (MEK) / methanol = 50 / 50 (volume ratio) (HSP value = 23.2), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (14) so ​​that the alkali concentration in the resulting treatment solution was 20% by weight. The results are summarized in Table 1.

[0219] [Preparation Example 15] Potassium hydroxide (KOH) was added to a mixed solvent of 1-butanol / methanol / water = 40 / 40 / 20 (volume ratio) (HSP value = 29.5) so that the alkali concentration in the resulting treatment solution was 1.3% by weight, thereby obtaining the adhesive treatment solution (15). The results are summarized in Table 1.

[0220] [Preparation Example 16] To a mixed solvent of methyl ethyl ketone (MEK) / methanol = 70 / 30 (volume ratio) (HSP value = 21.2), sodium hydroxide (NaOH) was added to obtain a tackifying agent treatment solution (16) with an alkali concentration of 0.8% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0221] [Preparation Example 17] To a mixed solvent of methyl ethyl ketone (MEK) / methanol = 70 / 30 (volume ratio) (HSP value = 21.2), sodium hydroxide (NaOH) was added to obtain a tackifying agent treatment solution (17) with an alkali concentration of 1.3% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0222] [Preparation Example 18] To a mixed solvent of methyl ethyl ketone (MEK) / methanol = 70 / 30 (volume ratio) (HSP value = 21.2), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (18) with an alkali concentration of 5.0% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0223] [Preparation Example 19] To a mixed solvent of decane / butanol = 40 / 60 (volume ratio) (HSP value = 18.8), potassium hydroxide (KOH) was added to obtain a tackening treatment solution (19) so that the alkali concentration in the resulting treatment solution was 1.5% by weight. The results are summarized in Table 1.

[0224] [Preparation Example 20] Potassium hydroxide (KOH) was added to a mixed solvent of 1-butanol / methanol / water = 60 / 20 / 20 (volume ratio) (HSP value = 28.9) to obtain a tackifying agent treatment solution (20) with an alkali concentration of 5.0% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0225] [Preparation Example 21] A mixed solvent of 1-butanol / 2-propanol (IPA) / water = 70 / 10 / 20 (volume ratio) (HSP value = 26.9) was to which potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (21) with an alkali concentration of 5.0% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0226] [Preparation Example 22] To a mixture of ethanol / water = 65 / 35 (volume ratio) (HSP value = 34.0), potassium hydroxide (KOH) was added to obtain a tackening treatment solution (C1) with an alkali concentration of 0.5% by weight. The results are summarized in Table 1.

[0227] [Preparation Example 23] A mixed solvent of cyclopentyl methyl ether (Cpme) / methanol = 50 / 50 (volume ratio) (HSP value = 17.7) was used as the adhesive treatment solution (C2). The results are summarized in Table 1.

[0228] [Preparation Example 24] To a mixed solvent of methyl ethyl ketone (MEK) / methanol = 50 / 50 (volume ratio) (HSP value = 23.2), potassium hydroxide (KOH) was added to obtain a tackifying agent treatment solution (C3) with an alkali concentration of 25.0% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0229] [Preparation Example 25] Potassium hydroxide (KOH) was added to a mixed solvent of benzyl alcohol / methanol / water = 40 / 20 / 40 (volume ratio) (HSP value = 33.5) to obtain a tackifying agent treatment solution (C4) with an alkali concentration of 1.3% by weight in the resulting treatment solution. The results are summarized in Table 1.

[0230] [Table 1]

[0231] [Examples 1-18 and Comparative Examples 1-4] <Manufacturing of water-soluble polymers> The adhesive layer was separated from the substrate by pressing the abrasive belt of a belt sander (BE-3210, RYOBI) equipped with an abrasive belt (grit size = #100, Makita) against the adhesive tape shown in Table 2 at a belt speed of 5.8 m / s. 0.7 g of the isolated adhesive was placed in a vial, and 20 g of adhesive treatment solution was added. The mixture was stirred at 50°C for 12 hours at a stirring speed of 600 rpm. The solvent was then removed by decantation to obtain the polymer. A large amount of water was added to the obtained polymer, and its solubility in water was evaluated. The results are shown in Table 2. ○: Completely dissolved in water. △: It was almost completely dissolved in water, but there were some undissolved particles. ×: It did not dissolve in water. Next, the polymers obtained in Examples 2, 4, and 5 were analyzed by IR and / or NMR to confirm that they were water-soluble polymers having the following constituent units. Table 2 shows the content ratios of constituent unit (I) and constituent unit (II) in the water-soluble polymers produced from the acrylic adhesive of "E-MASK" RP108C (manufactured by Nitto Denko Corporation). [ka] (In the formula, R 1 R represents a hydrogen atom. 2 (where M represents an alkyl group with 1 to 4 carbon atoms, and M represents a potassium cation or a sodium cation.)

[0232] [Table 2]

[0233] [Examples 19-31 and Comparative Examples 5-8] <Manufacturing of superabsorbent polymers> The adhesive layer was separated from the substrate by pressing the abrasive belt of a belt sander (BE-3210, RYOBI) equipped with an abrasive belt (grit size = #100, Makita) against the adhesive tape shown in Table 3 at a belt speed of 5.8 m / s. 0.7 g of the isolated adhesive was placed in a 50 ml sample tube, and 20 g of the adhesive treatment solution obtained in each preparation example shown in Table 3 was added. Then, 0.1 g (0.01 g for Examples 30 and 31) of the crosslinking agent shown in Table 3 was added, and the mixture was stirred at 600 rpm for 12 hours at 50°C. As a result, the superabsorbent polymer precipitated. Subsequently, the solvent was removed by decantation, and the superabsorbent polymer was dried at 120°C for 1.5 hours. Next, the dried superabsorbent polymer was ground in a mortar and pestle, and its water absorption was evaluated according to JIS K 7223-1996 (tea bag method). The results are shown in Table 3. ○: Water absorption rate is 10 times or more. ×: Water absorption rate is less than 10 times.

[0234] [Table 3]

[0235] The abbreviations for the crosslinking agents in Table 3 are as follows: EG; Ethylene glycol, PEG-200; Polyethylene glycol (number average molecular weight Mn200) PEG-400; Polyethylene glycol (number average molecular weight Mn400) [Industrial applicability]

[0236] The methods for producing water-soluble polymers and superabsorbent polymers according to embodiments of the present invention can produce water-soluble polymers and superabsorbent polymers from various types of adhesives under mild conditions, and are therefore suitable for recycling adhesive waste generated in large quantities at manufacturing sites and other locations.

Claims

1. A tackening solution containing a liquid and an alkaline compound, wherein the Hansen solubility parameter value is 25 or less, The liquid contains lower alcohols. The lower alcohol is at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, butanol, and 1-pentanol. The adhesive treatment solution, in which the concentration of the alkaline compound is 0.001% to 20% by weight, is brought into contact with an adhesive composed of at least one selected from the group consisting of acrylic adhesives and silicone adhesives. A method for producing water-soluble polymers.

2. The method for producing a water-soluble polymer according to claim 1, wherein the Hansen solubility parameter value of the liquid is 15 or more and 25 or less.

3. The method for producing a water-soluble polymer according to claim 1, wherein the adhesive is composed of an acrylic adhesive.

4. The method for producing a water-soluble polymer according to claim 1, wherein the concentration of the alkali compound in the processing solution is 0.01% by weight to 10% by weight.

5. A method for producing a water-absorbent polymer, comprising reacting a water-soluble polymer obtained by a method for producing a water-soluble polymer according to any one of claims 1 to 4 with a crosslinking agent.

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