Compounds, oxidatively degradable crosslinking agents, compositions, polymers, water-absorbing articles, methods for degrading polymers

Abstract

This invention provides compounds that can be used as oxidatively degradable crosslinking agents, which can form oxidatively degradable superabsorbent polymers that exhibit a short oxidative degradation time and excellent water absorption capacity. It also provides oxidatively degradable crosslinking agents, compositions, polymers, absorbent articles, and methods for degrading polymers. [Solution] A compound represented by general formula (1). TIFF2026123600000022.tif2178

Description

[Technical Field]

[0001] The present invention relates to compounds, oxidatively degradable crosslinking agents, compositions, polymers, water-absorbing articles, and methods for degrading polymers. [Background technology]

[0002] Superabsorbent polymers (SAPs) can absorb hundreds of times their own weight in water and are used in a variety of fields, including hygiene products such as disposable diapers, agriculture, and civil engineering. In particular, with the recent trend of a declining birthrate and aging population, the production of disposable diapers for the elderly is on the rise, and the proportion of disposable diapers in total waste is increasing year by year. Currently, used disposable diapers are mainly incinerated, but from the perspective of the SDGs (Sustainable Development Goals), there is a need to reduce the amount of incineration, and as one alternative method, superabsorbent polymers that have an oxidative decomposition capability that allows them to be rapidly decomposed by relatively inexpensive oxidizing agents such as sodium hypochlorite (hereinafter also referred to as "oxidatively decomposable superabsorbent polymers") are attracting attention. Typical examples of oxidatively decomposable superabsorbent polymers include polymers that have a structure derived from an oxidatively decomposable crosslinking agent, obtained by polymerizing monomers such as acrylic acid in the presence of an oxidatively decomposable crosslinking agent.

[0003] For example, Patent Document 1 discloses a compound (1,2-diacryloylhydrazine) having the following structure as an oxidatively degradable crosslinking agent used in the polymerization of oxidatively degradable superabsorbent polymers.

[0004] [ka] [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2021 / 131003 [Overview of the project] [Problems that the invention aims to solve]

[0006] The present inventors investigated the properties of the oxidatively degradable crosslinking agent described in Patent Document 1 by preparing an oxidatively degradable superabsorbent polymer obtained by polymerizing monomers such as acrylic acid in the presence of the above-mentioned oxidatively degradable crosslinking agent, and found that there is room for improvement to further reduce the time required for decomposition using an oxidizing agent (hereinafter also referred to as "oxidative decomposition time") and to further increase the amount of water absorbed.

[0007] Therefore, the object of the present invention is to provide a compound that can be used as an oxidatively degradable crosslinking agent and that can form an oxidatively degradable superabsorbent polymer that has a short oxidative degradation time and excellent water absorption capacity. Furthermore, the present invention aims to provide oxidatively degradable crosslinking agents, compositions, polymers, water-absorbing articles, and methods for degrading polymers. [Means for solving the problem]

[0008] The inventors have found that the above problems can be solved by the following configuration.

[0009] [1] A compound represented by the general formula (1) described later. [2] R 1 and R 2 The compound described in [1], wherein each independently represents a group represented by general formula (2) or general formula (3) described later. [3] A 1 However, -CO-O- or -CO-NR 3 - represents A 2 However, -CO- or -CO-NR 3 A compound described in [1] or [2] that represents -. [4] A compound according to any of [1] to [3], wherein the compound represented by the above general formula (1) is a compound represented by any of the formulas (1A) to (1D) described later. 〔5〕 An oxidative-decomposable crosslinking agent comprising the compound according to any one of 〔1〕 to 〔4〕. 〔6〕 A composition comprising the compound according to any one of 〔1〕 to 〔4〕 and a radically polymerizable compound. 〔7〕 The composition according to 〔6〕, wherein the radically polymerizable compound comprises at least one selected from the group consisting of acrylic acid, methacrylic acid, vinylsulfonic acid, acrylate ester, methacrylate ester, acrylamide, methacrylamide, N-vinylpyrrolidone, N-vinylformaldehyde, styrene, vinyl acetate, and maleimide. 〔8〕 The composition according to 〔6〕 or 〔7〕, wherein the radically polymerizable compound is acrylic acid or methacrylic acid. 〔9〕 A polymer comprising a repeating unit derived from a radically polymerizable compound and a repeating unit derived from a compound represented by the following general formula (1). 〔10〕 R 1 and R 2 each independently represent a group represented by the following general formula (2) or a group represented by the following general formula (3). The polymer according to 〔9〕. 〔11〕 A 1 represents -CO-O- or -CO-NR 3 -, and A 2 represents -CO- or -CO-NR 3 -. The polymer according to 〔9〕 or 〔10〕. 〔12〕 The polymer according to any one of 〔9〕 to 〔11〕, wherein the compound represented by the above general formula (1) is a compound represented by any one of the following formulas (1A) to (1D). 〔13〕 A water-absorbing article comprising the polymer according to any one of 〔9〕 to 〔12〕. 〔14〕 A method for decomposing a polymer, comprising contacting the polymer according to any one of 〔9〕 to 〔12〕 with an oxidizing agent to decompose the polymer. 〔15〕 The method for decomposing a polymer according to 〔14〕, wherein the oxidizing agent is sodium hypochlorite.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a compound that can be used as an oxidatively degradable crosslinking agent, which can form an oxidatively degradable superabsorbent polymer that has a short oxidative degradation time and excellent water absorption capacity. Furthermore, the present invention can provide oxidatively degradable crosslinking agents, compositions, polymers, water-absorbing articles, and methods for degrading polymers. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0012] Furthermore, in this specification, "(meth)acryloyl group" refers to both an acryloyl group and a methacryloyl group, and "(meth)acrylic" refers to both acrylic and methacrylic.

[0013] Furthermore, in the notation of groups (atomic groups) in this specification, notations that do not specify whether they are substituted or unsubstituted include both groups with and without substituents. For example, "alkyl group" includes not only alkyl groups without substituents (unsubstituted alkyl groups) but also alkyl groups with substituents (substituted alkyl groups). Furthermore, in this specification, an organic group refers to a group containing one or more carbon atoms.

[0014] Furthermore, the bonding direction of divalent groups as expressed herein is not limited unless otherwise specified. For example, in a compound represented by the formula "XYZ", if Y is -COO-, Y may also be -CO-O- or -O-CO-. Also, the above compound may be "X-CO-OZ" or "XO-CO-Z".

[0015] Furthermore, in this specification, "solids" of a composition means the components that form the composition layer formed using the composition, and if the composition contains a solvent (organic solvent, water, etc.), it means all components excluding the solvent. In addition, liquid components that form the composition layer are also considered to be solids.

[0016] [Compound] The compound of the present invention is a compound represented by the general formula (1) described later (hereinafter also referred to as the "specific compound"). The compounds of the present invention can be suitably used as oxidatively degradable crosslinking agents. Polymers obtained by polymerizing monomers such as acrylic acid in the presence of the compounds of the present invention as oxidatively degradable crosslinking agents exhibit a short oxidative decomposition time and excellent water absorption (high water absorption).

[0017] Although this is not entirely clear, the inventors speculate the following: The specific compound has a structure with relatively low reactivity (radical polymerization reactivity). As a result, it is presumed that polymers obtained using this specific compound as an oxidative decompositionable crosslinking agent have excellent water absorption capacity because the crosslink density does not become excessively high, making them prone to swelling upon water absorption. Furthermore, it is presumed that the above polymer also has a short oxidative decomposition time due to its structure, which does not result in an excessively high crosslink density. Furthermore, the inventors have confirmed that when the above polymer, after absorbing water, is oxidatively decomposed with an oxidizing agent (for example, sodium hypochlorite), the viscosity of the solution containing the decomposed polymer is low, and the processing performance after decomposition is also excellent.

[0018] Hereinafter, when the compound of the present invention is used as the oxidative decomposition agent, the oxidative decomposition time of the polymer obtained is shorter, the amount of water absorbed is greater, and / or the viscosity of the solution obtained by applying an oxidizing agent to the polymer after water absorption and oxidative decomposition is lower, this is also referred to as "the effects of the present invention being superior."

[0019] The following describes compounds represented by general formula (1) (specific compounds). [Specific compound]

[0020] [ka]

[0021] In general formula (1), A 1 and A 2 These are -CO-, -CO-O-, and -CO-NR, each independently. 3 -, -SO2-, or -SO2-NR 4 - represents A 1 and A 2 -CO-, -CO-O-, or -CO-NR are more likely to produce superior effects in the present invention. 3 - is preferred to represent, A 1 and A 2 One of them is -CO-O- or -CO-NR 3 - represents -CO- or -CO-NR 3 It is preferable to represent it as -. Furthermore, in terms of the likelihood of the effects of the present invention being even better, A 1 and A 2 It is also preferable that they represent different structures from one another.

[0022] R 3 and R 4 Each of these independently represents a hydrogen atom, an alkyl group, or an alkenyl group. R 3 and R 4 The alkyl group represented by may be linear, branched, or cyclic, but it is preferably linear or branched, and more preferably linear. The number of carbon atoms in the alkyl group is not particularly limited, but is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3. R 3 and R 4 The alkenyl group represented by may be linear, branched, or cyclic, but is preferably linear or branched, and more preferably linear. The number of carbon atoms in the alkenyl group is not particularly limited, but is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 4. Specific examples of the above alkenyl groups include vinyl groups, allyl groups, isopropenyl groups, and 2-methylallyl groups (2-methyl-2-propenyl groups).

[0023] R 3 and R 4 It is preferable, and more preferable, that the present invention represents a hydrogen atom or an alkenyl group, as this tends to result in better effects.

[0024] R 1 and R 2 Each of these independently represents a group that can be expressed by any of the following general formulas (2) to (6).

[0025] [ka]

[0026] In general formula (2), R 5 represents a hydrogen atom or a methyl group.

[0027] In general formula (3), R 6 represents a hydrogen atom or a methyl group.

[0028] In general formula (4), R 7 represents a hydrogen atom or a methyl group. L 1 L represents an alkylene group. 1 The alkylene group represented by is preferably linear or branched. The number of carbon atoms in the alkylene group is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1 to 2.

[0029] In general formula (5), R 8 represents a hydrogen atom or a methyl group. L 2 L represents an alkylene group. 2The alkylene group represented by is preferably linear or branched. The number of carbon atoms in the alkylene group is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1 to 2.

[0030] In general formula (6), L 3 L represents an alkylene group. 3 The alkylene group represented by is preferably linear or branched. The number of carbon atoms in the alkylene group is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 4, and particularly preferably 1 to 2.

[0031] R 1 and R 2 It is preferable that the group represents the group represented by general formula (2) or the group represented by general formula (3), as this tends to result in better effects of the present invention.

[0032] However, in general formula (1), A 1 When -CO- represents, A 2 -CO-O-, -CO-NR 3 -, -SO2-, or -SO2-NR 4 - represents A 1 When -CO-O- represents, A 2 -CO-, -CO-NR 3 -, -SO2-, or -SO2-NR 4 - represents A 1 ga-CO-NR 3 When representing -, R 1 This represents a group represented by any of the general formulas (2), (3), (5), and (6). 2 ga-CO-NR 3 When representing -, R 2 This represents a group that can be represented by any of the general formulas (2), (3), (5), and (6).

[0033] In general formula (1), A is more likely to produce superior effects. 1 However, -CO-O- or -CO-NR 3 - represents A 2 However, -CO- or -CO-NR3 - is preferred to represent, A 1 represents -CO-O-, A 2 -CO- or -CO-NR 3 - represents, or A 1 ga-CO-NR 3 - represents A 2 It is more preferable that -CO- represents A 1 represents -CO-O-, A 2 ga-CO-NR 3 It is even more preferable to represent it as -.

[0034] Furthermore, in general formula (1), the number of crosslinking groups can be 2 to 4, and 2 or 3 are preferred, with 3 being more preferred, in terms of superior water absorption. Note that in general formula (1), when the number of crosslinking groups is 3 or 4, R 1 and R 2 In addition to the predetermined crosslinkable groups represented by A, 1 and A 2 One or both of are -CO-NR 3 - or -SO2-NR 4 - represents, and R 3 and R 4 This applies when it represents an alkenyl group.

[0035] Specific examples of the specified compounds include, for example, compounds represented by any of the following formulas (1A) to (1D). Among the specified compounds, those represented by formulas (1B) to (1D) are preferred in that they exhibit superior effects of the present invention.

[0036] [ka]

[0037] The specific compound can be synthesized by known methods. Certain compounds can be suitably used as oxidatively degradable crosslinking agents. Polymers synthesized using specific compounds have repeating units derived from these specific compounds, and the hydrazine structural portion of these repeating units can be oxidatively decomposed using an oxidizing agent, making them suitable for various applications as oxidatively decomposable polymers. Examples of applications for oxidatively decomposable polymers include oxidatively decomposable adhesives and oxidatively decomposable coatings. Furthermore, polymers obtained by copolymerizing specific compounds with raw material monomers for superabsorbent polymers (SAP) (e.g., (meth)acrylic acid) can be suitably used as oxidatively decomposable superabsorbent polymers.

[0038] [Oxidative decomposition crosslinking agent] The oxidative decomposition crosslinking agent of the present invention consists of a compound represented by the general formula (1) described above (specific compound). The specific compound is as previously stated.

[0039] [Composition] The composition of the present invention comprises a compound represented by the general formula (1) described above (a specific compound) and a radical polymerizable compound. The components that the composition of the present invention may contain are described in detail below.

[0040] [Specific compound] The composition of the present invention contains a specific compound. The specific compound is as previously described, and the preferred embodiment is also the same. The specific compound may be used alone or in combination of two or more compounds. The content of the specific compound in the composition of the present invention (the total content if multiple types are included) can be adjusted as appropriate so that the cured product (polymer) formed using the composition of the present invention, as described later, becomes the desired polymer. The content of the specific compound in the composition of the present invention is preferably such that, when a cured product (polymer) is formed using the composition of the present invention, the repeating units derived from the specific compound amount to 0.001 mol% or more of the total repeating units of the polymer, more preferably 0.01 mol% or more, and even more preferably 0.05 mol% or more. As an upper limit, it is preferably 20 mol% or less, more preferably 15 mol% or less, even more preferably 10 mol% or less, particularly preferably 5 mol% or less, and most preferably 1 mol% or less.

[0041] [Radical polymerizable compounds] The composition of the present invention contains a radical polymerizable compound. Radical polymerizable compounds are typically compounds that have a radical polymerizable group. The types of radical polymerizable groups are not particularly limited, but examples include ethylenically unsaturated groups such as (meth)acryloyl groups, (meth)acrylamide groups, vinyl groups, allyl groups, styryl groups, and maleimide groups. The radical polymerizable compound may be either a monofunctional radical polymerizable compound (a compound having one radical polymerizable group) or a polyfunctional radical polymerizable compound (a compound having two or more radical polymerizable groups), but it is preferable that it be a monofunctional radical polymerizable compound. The number of functional groups (number of radical polymerizable groups) in a polyfunctional radical polymerizable compound is not particularly limited, but is preferably 2 to 10, more preferably 2 to 6, and even more preferably 2 to 3.

[0042] The monofunctional radically polymerizable compound is not particularly limited. For example, acid group-containing unsaturated monomers such as (meth)acrylic acid, vinylphosphonic acid, vinylsulfonic acid, maleic acid, itaconic acid, cinnamic acid, vinylsulfonic acid, allyltoluenesulfonic acid, vinyltoluenesulfonic acid, styrenesulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, 2-(meth)acryloylpropanesulfonic acid, 2-hydroxyethyl (meth)acryloyl phosphate; N-vinylpyrrolidone; N-vinylformaldehyde; styrene; vinyl acetate; maleimide; (meth)acrylic acid esters; (meth)acrylamides; (meth)acrylic acid thioesters; (meth)acrylonitrile; butadiene and the like can be mentioned.

[0043] The radically polymerizable compound is preferably at least one selected from the group consisting of (meth)acrylic acid, vinylsulfonic acid, (meth)acrylic acid ester, (meth)acrylamide, N-vinylpyrrolidone, N-vinylformaldehyde, styrene, vinyl acetate, and maleimide, and more preferably (meth)acrylic acid.

[0044] It is also preferable that the radically polymerizable compound is selected from those other than monofunctional vinyl monomers having a structural site represented by any of the following general formulas (R1) to (R4). (R1) -CO-OR X (R2) -CO-SR X (R3) -CO-N(R X )2 (R4) -CO-NR Y In general formulas (R1) to (R3), R X represents a monovalent organic group. In general formula (R4), R Y represents a divalent organic group. In general formula (R4), when R Y represents a divalent organic group, it means that R YThe intention is that both bonds of the divalent organic group represented by the formula (R4) will bond to the nitrogen atom explicitly shown in the general formula (R4) to form a ring structure (a ring structure that includes the nitrogen atom explicitly shown in the general formula (R4) as a ring member atom, such as a morpholine ring, piperidine ring, piperazine ring, etc.).

[0045] Radical polymerizable compounds may be used individually or in combination of two or more. The content of the radical polymerizable compound in the composition of the present invention is preferably such that, when a cured product (polymer) is formed using the composition of the present invention, the repeating units derived from the radical polymerizable compound account for 80 mol% or more of the total repeating units of the polymer, more preferably 85 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 99 mol% or more. As an upper limit, it is preferably 99.999 mol% or less, more preferably 99.99 mol% or less, and even more preferably 99.95 mol% or less.

[0046] The content of radical polymerizable compounds in the composition of the present invention (total content if multiple types are included) is preferably 30% by mass or more, and more preferably 50% by mass or more, based on the total solid content of the composition of the present invention. The upper limit is preferably 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, based on the total solid content of the composition of the present invention.

[0047] [Polymerization initiator] The composition of the present invention preferably contains a polymerization initiator. Examples of polymerization initiators include photoradical polymerization initiators and thermal radical polymerization initiators, with thermal radical polymerization initiators being preferred. While there are no particular limitations on polymerization initiators, examples include persulfates such as persulfuric acid, sodium persulfate, potassium persulfate, and ammonium persulfate; hydroperoxides such as hydrogen peroxide and tert-butyl hydroperoxide; peroxydicarbonates such as di(4-tert-butylcyclohexyl)peroxydicarbonate; and azo compounds such as 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methylpropionitrile), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(N-butyl-2-methylpropionamide), and dimethyl-2,2-azobis(2-methylpropionate), which are examples of radical polymerization initiators.

[0048] If the composition of the present invention contains a polymerization initiator, the content of the polymerization initiator (or the total content if multiple types are included) is preferably 1 to 50% by mass, and more preferably 5 to 30% by mass, relative to the total solid content of the composition of the present invention. Polymerization initiators may be used alone or in combination of two or more.

[0049] 〔solvent〕 The composition of the present invention may contain a solvent. The solvent is not particularly limited as long as it does not react with the specific compound and the radical polymerizable compound, and does not inhibit their polymerization reactions. Specific examples of solvents include, for example, purified water such as distilled water and deionized water, and waters such as ultrapure water; for example, aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, n-heptane, n-octane, and isooctane, and petroleum ether; for example, halogenated aliphatic hydrocarbon solvents such as dichloromethane, trichloromethane (chloroform), and tetrachloromethane (carbon tetrachloride); for example, aromatic hydrocarbon solvents such as benzene, toluene, and xylene; for example, ether solvents such as diethyl ether, diisopropyl ether, methyl-tert-butyl ether, cyclopentyl methyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, and 1,4-dioxane; for example, glycol ether solvents such as ethylene glycol dimethyl ether, propylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether; for example, ethylene glycol Glycol ether acetate solvents such as glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, and dipropylene glycol monoethyl ether acetate; for example, 2-propanone (acetone), 2-butanone (ethyl methyl ketone), and 4-methyl Examples of ester solvents include ketone solvents such as -2-pentanone (methyl isobutyl ketone); ester solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, ethyl butyrate, and isoamyl butyrate; and amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, 1-methyl-2-pyrrolidinone (N-methylpyrrolidone), and 1,3-dimethyl-2-imidazolidinone (dimethylethylene urea). The solvent may be used alone or in combination of two or more types.

[0050] From the viewpoint of practicality and economics, the amount of solvent used is preferably such that the total solvent content relative to the total mass of the composition of the present invention is 0 (substantially no solvent) to 300% by mass, and more preferably 10% to 100% by mass.

[0051] [Other ingredients] The composition of the present invention may contain other components besides those mentioned above. These other components are not particularly limited, but examples include polymerization inhibitors, fillers, plasticizers, preservatives, antioxidants, UV absorbers, flame retardants, antistatic agents, pigments, elastomers (e.g., styrene-based block copolymers) for adjusting the rubber properties of the cured product, thiol compounds, tertiary amine compounds, and adhesion promoters.

[0052] [Method for synthesizing cured polymers] By subjecting the composition of the present invention to heat treatment or exposure treatment, the polymerization of the radical polymerizable compound and specific compound in the composition of the present invention can proceed, thereby forming a cured product (polymer).

[0053] The polymerization method for the polymer is not particularly limited, but examples include aqueous solution polymerization, reversed-phase suspension polymerization, spray polymerization, droplet polymerization, bulk polymerization, and precipitation polymerization, with aqueous solution polymerization being preferred.

[0054] When polymerization is carried out by heat treatment, the reaction temperature is preferably 120°C or lower in order to suppress the thermal decomposition of the hydrazine structural portion in the specific compound. The reaction temperature is usually 40 to 120°C, preferably 45 to 110°C, and more preferably 50 to 105°C. The reaction time can be selected as appropriate, but it is usually 0.5 to 5 hours. The heat treatment may be carried out in an air environment, or in a nitrogen-purged or argon-purged environment.

[0055] When polymerization is carried out by exposure treatment, the light source used for exposure can be appropriately selected as long as it emits light of a wavelength that exposes the polymerization initiator. Specifically, examples include ultra-high pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, and LEDs (Light Emitting Diodes). As for the amount of exposure, there are no particular restrictions on the amount of light irradiation (exposure) as long as the polymerization reaction proceeds well. Furthermore, when polymerization is carried out by exposure treatment, the reaction temperature is preferably adjusted to 120°C or below in order to suppress the thermal decomposition of the hydrazine structural portion in the specific compound. The reaction time can be appropriately selected, but is usually 0.5 to 5 hours. The exposure treatment may be carried out in an air environment, or in a nitrogen-purged or argon-purged environment.

[0056] When polymer polymerization is carried out by aqueous solution polymerization, after the polymerization is complete, the reaction solution is cooled as needed, the polymer precipitated in the solution is filtered off, and the filtered polymer is dried. Alternatively, the filtered polymer may be purified by adding it to a suitable precipitating agent as needed.

[0057] [polymer] The polymer of the present invention (hereinafter also referred to as the "specific polymer") includes repeating units derived from a radical polymerizable compound (hereinafter also referred to as the "repeating unit X1") and repeating units derived from the compound represented by the general formula (1) described above (the specific compound) (hereinafter also referred to as the "repeating unit Y1"). The compound represented by the general formula (1) (the specific compound) is as described above, and the preferred embodiments are also the same. The specific polymer can be formed using the composition of the present invention described above.

[0058] The radical polymerizable compound constituting the repeating unit X1 in the specific polymer (corresponding to the raw material monomer of the repeating unit X1) is the same as the radical polymerizable compound listed above as a component of the composition of the present invention, and the preferred embodiment is also the same. Furthermore, if the repeating unit X1 in the specific polymer has an acidic group, some or all of the acidic group may be anionized. Also, some or all of the acidic group may form a salt structure with alkali metals, etc. The repeating unit X1 may be used alone or in combination of two or more types.

[0059] In a specific polymer, the content of repeating units X1 (or the total content if multiple types are included) is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, particularly preferably 95 mol% or more, and most preferably 99 mol% or more, relative to the total repeating units of the specific polymer. The upper limit is preferably 99.999 mol% or less, more preferably 99.99 mol% or less, and even more preferably 99.95 mol% or less.

[0060] The repeating unit X1 may also preferably include a repeating unit represented by the following general formula (X1A) (hereinafter also referred to as "repeating unit X1A").

[0061] [ka]

[0062] In general formula (X1A), R X1 represents a hydrogen atom or a monovalent substituent. R X1 Examples of monovalent substituents represented by include alkyl groups (preferably having 1 to 6 carbon atoms), hydroxyl groups, amino groups, mercapto groups, acyl groups (preferably having 2 to 6 carbon atoms), and alkyl groups (preferably having 1 to 6 carbon atoms) having one or more substituents selected from hydroxyl groups, amino groups, mercapto groups, and acyl groups (preferably having 2 to 6 carbon atoms). R X1 Of these, hydrogen atoms or alkyl groups having 1 to 3 carbon atoms are preferred, and hydrogen atoms or methyl groups are more preferred.

[0063] A X1 -COO -, -SO3 - , or, -PO3 - represents. A X1 is -COO - is preferred. Y X1 is H + , Li + , Na + , or, K + represents. Incidentally, when A X1 is -COO - is taken as an example, when Y X1 is H + represents, the site represented by -A<00001​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​In a specific polymer, the content of repeating units Y1 (or the total content if multiple types are included) is preferably 0.001 mol% or more, more preferably 0.01 mol% or more, and even more preferably 0.05 mol% or more, relative to the total repeating units of the specific polymer. The upper limit is preferably 20 mol% or less, more preferably 15 mol% or less, even more preferably 10 mol% or less, particularly preferably 5 mol% or less, and most preferably 1 mol% or less.

[0066] [Water absorbent articles] The water-absorbing article of the present invention contains a specific polymer. Absorbent articles refer to articles used for the purpose of absorbing water, such as disposable diapers, sanitary napkins, adult incontinence products, pet sheets and other sanitary materials, soil water retention agents for agriculture and horticulture, and water-stopping agents for industry. Absorbent articles typically consist of an absorbent material and a component that holds the absorbent material. Disposable diapers, an example of an absorbent article, have a structure consisting of an absorbent material and a surface material that encloses and holds the absorbent material, and specific polymers may be used as the absorbent material.

[0067] [Methods for breaking down polymers] The present invention provides a method for decomposing a polymer by contacting a specific polymer with an oxidizing agent. Examples of oxidizing agents include oxygen acids and their salts (e.g., alkali metal salts such as sodium salts); elemental chlorine, elemental bromine, elemental iodine, elemental sulfur, and solutions containing them; nitrogen oxides such as nitrogen dioxide and nitric oxide; oxygen compounds such as superoxides and peroxides (e.g., hydrogen peroxide); transition metal compounds such as transition metal salts and transition metal complexes; and the like. The oxidizing agent is preferably sodium hypochlorite due to its low cost and excellent availability. The oxidizing agent may be used alone or in combination of two or more types.

[0068] There are no particular limitations on the method of contact between the specific polymer and the oxidizing agent, but examples include adding the specific polymer to an aqueous solution containing the oxidizing agent and stirring, and spraying the aqueous solution containing the oxidizing agent onto the specific polymer. In a method of adding a specific polymer to an aqueous solution containing an oxidizing agent and stirring, the concentration of the aqueous solution containing the oxidizing agent is not particularly limited, but is preferably 0.1 to 50% by mass, and more preferably 1 to 30% by mass. The temperature of the aqueous solution is not particularly limited, but is preferably 10 to 30°C, and more preferably 15 to 25°C. The stirring time is not particularly limited, but is preferably 0.05 to 24 hours, and more preferably 0.5 to 3 hours. [Examples]

[0069] The present invention will be described in more detail below based on the following examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the following examples.

[0070] [Example 1] Synthesis of N,N,N,N-tetraallylhydrazine-1,2-dicarboxamide (TAHC) (1) Synthesis of diallylcarbamoyl chloride 4.89 g (16.5 mmol: Fujifilm Wako Pure Chemical Industries, Ltd.) of triphosgene was mixed with 40 mL of t-butyl methyl ether (TBME) and cooled to 5°C. 4.17 g (41.2 mmol: Fujifilm Wako Pure Chemical Industries, Ltd.) of triethylamine and 4.00 g (41.2 mmol: Fujifilm Wako Pure Chemical Industries, Ltd.) of diallylamine were added dropwise, and the mixture was reacted at 25°C for 2 hours. After the reaction was complete, 40 mL of deionized water was added for washing. The solvent was removed by distillation under reduced pressure to obtain 5.33 g (33.39 mmol, yield: 81%) of diallylcarbamoyl chloride.

[0071] [ka]

[0072] (2) Synthesis of TAHC 0.95 g (15.18 mmol: manufactured by Mitsubishi Gas Chemical Next Co., Ltd.) of 80% hydrazine monohydrate, 3.07 g (30.34 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 4.31 g (30.34 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed with 10 mL of TBME and cooled to 5°C. 5.33 g (33.39 mmol) of diallylcarbamoyl chloride obtained in (1) above was dissolved in 10 mL of TBME and added dropwise, and the mixture was reacted at 5°C for 1 hour. After removing the inorganic salt by filtration, the mixture was washed with deionized water, and the solvent was removed by distillation under reduced pressure concentration. The resulting crystals were filtered with heptane to obtain 2.12 g (7.62 mmol, yield: 50%) of TAHC as a white powder.

[0073] Below, TAHC 1 This shows an H-NMR spectrum. 1 H-NMR (CDCl3, 400Hz) δ 6.39 (s, 2H), 5.86-5.77 (m, 4H), 5.24 (t, 8H), 3.55 (d, 8H)

[0074] [ka]

[0075] [Example 2] Synthesis of allyl-2-(diallylcarbamoyl)hydrazine-1-carboxylate (ADAHC) (1) Synthesis of diallylcarbamoyl chloride 11.87 g (40 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) of triphosgene was mixed with 100 mL of methylene chloride and cooled to 5°C. 10.12 g (100 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) of triethylamine and 9.71 g (100 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) of diallylamine were added dropwise, and the mixture was reacted at 25°C for 2 hours. After the reaction was complete, 100 mL of deionized water was added for washing. The solvent was removed by distillation under reduced pressure to obtain 15.61 g (97.80 mmol, yield: 98%) of diallylcarbamoyl chloride.

[0076] [ka]

[0077] (2) Synthesis of N,N-diallylhydrazine carboxyamide 6.26 g (100 mmol: manufactured by Mitsubishi Gas Chemical Next Co., Ltd.) of 80% hydrazine monohydrate was mixed with 20 mL of tetrahydrofuran (THF) and cooled to 5°C. 3.20 g (20 mmol) of diallylcarbamoyl chloride obtained in (2) above was added dropwise, and the mixture was reacted at 25°C for 4 hours. After the reaction was complete, the solvent was removed by distillation under reduced pressure, and the solvent was replaced with methylene chloride. The mixture was washed with deionized water, dehydrated with sodium sulfate, and filtered. By distillation of the solvent under reduced pressure, 3.06 g (19.72 mmol, yield: 99%) of a colorless oily liquid N,N-diallylhydrazinecarboxamide was obtained.

[0078] [ka]

[0079] (3) Synthesis of ADAHC 0.93 g (6.00 mmol) of N,N-diallylhydrazine carboxamide obtained in (2) above, and 0.95 g (9.00 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed with 10 mL of THF and cooled to 5°C. 0.87 g (7.22 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise, and the mixture was reacted at 5°C for 1 hour, then at 25°C for 1 hour. After the reaction was complete, the resulting salt was filtered, ethyl acetate was added, washed with deionized water, and dehydrated with sodium sulfate. After filtration, the solvent was removed by distillation under reduced pressure to obtain 1.22 g (5.10 mmol, yield: 85%) of ADAHC as a white powder.

[0080] Below is ADAHC's 1 This shows an H-NMR spectrum. 1 H-NMR (CDCl3, 400Hz) δ 6.53 (s, 1H), 6.30 (s, 1H), 5.96-5.76 (m, 3H), 5.35-5.22 (m, 6H), 4.63 (d, 2H), 3.90 (d, 4H)

[0081] [ka]

[0082] [Example 3] Synthesis of N,N-diallyl-2-methacryloylhydrazine-1-carboxamide (DAMHC) 1.01 g (6.51 mmol) of N,N-diallylhydrazine carboxamide and 1.03 g (9.72 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) obtained in (2) of [Example 2] were mixed with 10 mL of THF and cooled to 5°C on ice. 0.81 g (7.75 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) methacrylate chloride was added dropwise, and the mixture was reacted at 5°C for 1 hour, then at 25°C for 1 hour. The resulting salt was filtered, the solvent was removed by distillation under reduced pressure, and the mixture was purified by silica gel column chromatography to obtain 1.01 g (4.52 mmol, yield: 69%) of DAMHC, a white viscous solid.

[0083] Below, DAMHC1 This shows an H-NMR spectrum. 1 H-NMR (CDCl3, 400Hz) δ 8.57 (s, 1H), 7.20 (s, 1H), 5.82-5.77 (m, 3H), 5.40 (s, 1H), 5.29-5.15 (m, 4H), 3.91 (t, 4H), 1.97 (s, 3H)

[0084] [ka]

[0085] [Example 4] Synthesis of allyl-2-methacryloylhydrazine-1-carboxylate (AMHC) (1) Synthesis of methacrylate hydrazide 10.01 g (200 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) of hydrazine monohydrate was added to 30 mL of chloroform and cooled to 5°C. 6.17 g (40 mmol: manufactured by Tokyo Chemical Industry Co., Ltd.) of methacrylic anhydride was added dropwise, and the mixture was reacted at 5°C for 30 minutes, followed by 25°C for 30 minutes. After the reaction was complete, deionized water was added, and the mixture was separated with methylene chloride, followed by sodium sulfate to dehydrate it. After filtration, the solvent was removed by distillation under reduced pressure to obtain 0.96 g (9.59 mmol, yield: 24%) of methacrylic acid hydrazide as a white powder.

[0086] [ka]

[0087] (2) Synthesis of AMHC 0.95 g (9.49 mmol) of methacrylate hydrazide obtained in (1) above, and 1.51 g (14.25 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed with 10 mL of methylene chloride and cooled to 5°C. 1.38 g (11.45 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise, and the mixture was reacted at 5°C for 20 minutes, then at 25°C for 4 hours. After filtering the resulting salt, the solvent was removed by distillation under reduced pressure to obtain 0.86 g (4.67 mmol, yield: 49%) of colorless oily liquid AMHC.

[0088] Below, AMHC 1 This shows an H-NMR spectrum. 1 H-NMR (CDCl3, 400Hz) δ 8.39 (s, 1H), 7.37 (s, 1H), 5.96-5.77 (m, 2H), 5.44-5.22 (m, 3H), 4.71-4.63 (m, 2H), 1.97 (s, 3H)

[0089] [ka]

[0090] [Examples 5-8] Synthesis of Polymers 1.08 g of acrylic acid (14.99 mmol: manufactured by Toagosei Co., Ltd.), the crosslinking agent synthesized in Examples 1-4 (0.5 mol% or 0.25 mol%), and 9 mL of deionized water were placed in a test tube and bubbled with N2 at 5°C for 30 minutes. 0.21 g of the initiator 4,4'-azobis(4-cyanovaleric acid) (0.75 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the mixture was heated to 70°C to obtain a gel. The obtained gel was crushed into small pieces and neutralized with 7.5 mL of 2 M sodium hydroxide aqueous solution (15 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to obtain gel-like crosslinked polymer compounds 1-1 to 1-4 (crosslinking agent amount 0.5 mol%) and 2-1 to 2-4 (crosslinking agent amount 0.25 mol%).

[0091] [Comparative Example 1] Synthesis of the comparative polymer (1) Synthesis of comparative crosslinking agent (1,2-dimethacryloylhydrazine (MMH)) 100 g (2.00 mol: manufactured by Mitsubishi Gas Chemical Next Co., Ltd.), 337 g (3.18 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 226 g (1.59 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) of 80% hydrazine monohydrate were mixed with 2 L of chloroform and cooled to 5°C. 333 g (3.19 mmol: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) of methacrylate chloride was added dropwise, and the mixture was reacted at 25°C for 19 hours. After the reaction was complete, the mixture was heated to 56°C, and the salt was removed by filtration. The solvent was removed by vacuum concentration, 2 L of t-butyl methyl ether was added to crystallize, and the mixture was filtered and dried to obtain 199 g (1.18 mol, yield 74%) of white powder 1,2-dimethacryloylhydrazine (MMH).

[0092] [ka]

[0093] (2) Synthesis of comparative polymers The gel-like comparative polymer compounds 1-R1 (0.5 mol% crosslinking agent) and 2-R1 (0.25 mol% crosslinking agent) were obtained in the same manner as in Examples 5 to 8, except that 1,2-dimethacryloylhydrazine (MMH) (0.5 mol% or 0.25 mol%) obtained in (1) above was used instead of the crosslinking agent (0.5 mol% or 0.25 mol%) synthesized in Examples 1 to 4.

[0094] [Comparative Example 2] Synthesis of the comparative polymer Except for using pentaerythritol triallyl ether (trade name "P-30M", manufactured by Osaka Soda Co., Ltd.) instead of the crosslinking agent (0.5 mol% or 0.25 mol%) synthesized in Examples 1 to 4, the same procedure as in Examples 5 to 8 was used to obtain gel-like comparative polymer compounds 1-R2 (0.5 mol% crosslinking agent) and 2-R2 (0.25 mol% crosslinking agent).

[0095] [Various evaluations] [1] Evaluation 1 (Evaluation of water absorption) The crosslinked polymer compounds 1-1 to 1-4 and comparative polymer compounds 1-R1 to 1-R2 (all containing 0.5 mol% crosslinking agent) obtained in the upper section were thoroughly dried. Next, 0.1 g of each dried polymer compound was weighed and sealed in a bag made of 1 μm nylon mesh. For comparison, an empty bag of the same size was also prepared. Beakers containing 500 mL of deionized water were prepared and each was immersed. After immersion for 96 hours and draining for 10 minutes, the mass was measured. The water absorption rate (g / g) of crosslinked polymer compounds 1-1 to 1-4 and comparative polymer compounds 1-R1 to 1-R2 was calculated using the following formula (A) and evaluated according to the following evaluation criteria. In formula (A) below, "mass of sample" is 0.1 g. An evaluation of "B" or higher is preferable for water absorption, and "A" is most preferable.

[0096] Formula (A) Water absorption (g / g) = (Mass of the bag containing the sample after draining - Mass of the empty bag after draining - Mass of the sample) / Mass of the sample

[0097] <Evaluation Criteria> "A": 1000g / g or more "B": 300g / g or more, less than 1000g / g "C": Less than 300g / g

[0098] [2] Evaluation 2 (Evaluation of oxidative decomposition time and viscosity after decomposition) The crosslinked polymer compounds 2-1 to 2-4 and comparative polymer compounds 2-R1 to 2-R2 (all containing 0.25 mol% crosslinking agent) obtained in the upper section were thoroughly dried. Next, 0.1 g of each dried polymer compound was weighed, and 2 mL of deionized water was added to each, allowing them to absorb water for 17 hours. 2 mL of sodium hypochlorite aqueous solution was added to the absorbed gel and stirred. The time until the gel completely decomposed (oxidative decomposition time) was measured visually. The viscosity of the solution after decomposition (post-decomposition viscosity) was measured using a B-type viscometer. The obtained oxidative decomposition time and post-decomposition viscosity were classified according to the evaluation criteria below, and the performance of each polymer compound was evaluated. For the oxidative decomposition time, a rating of "C" or higher is preferable, "B" or higher is more preferable, and "A" is most preferable. For the post-decomposition viscosity, a rating of "B" or higher is preferable, and "A" is most preferable.

[0099] <Evaluation Criteria: Oxidative Decomposition Time> "A": Less than 10 minutes "B": 10 minutes or more, less than 15 minutes "C": 15 minutes or more, less than 20 minutes "D": 20 minutes or more

[0100] <Evaluation criteria: Viscosity after decomposition> "A": Less than 9.0 mPa·s "B": 9.0 mPa·s or higher, less than 13.0 mPa·s "C": 13.0 mPa·s or higher, less than 15.0 mPa·s “D”: 15.0mPa·s or more

[0101] Table 1 is shown below. In Table 1, crosslinked polymer compounds 1-1, 1-2, 1-3, and 1-4, as well as comparative polymer compounds 1-R1 and 1-R2, are all polymer compounds polymerized with a crosslinking agent content of 0.25 mol%. Crosslinked polymer compounds 2-1, 2-2, 2-3, and 2-4, as well as comparative polymer compounds 2-R1 and 2-R2, are all polymer compounds polymerized with a crosslinking agent content of 0.5 mol%. Furthermore, the crosslinking agent TAHC corresponds to the compound represented in (1A) above, ADAHC corresponds to the compound represented in (1B) above, DAMHC corresponds to the compound represented in (1C) above, and AMHC corresponds to the compound represented in (1D) above.

[0102] [Table 1]

[0103] The results in the table clearly show that polymers obtained by polymerizing monomers such as acrylic acid in the presence of the compound from the examples as an oxidatively decomposable crosslinking agent exhibit a short oxidative decomposition time and high water absorption. Furthermore, it is clear that when the polymer after water absorption is oxidatively decomposed with an oxidizing agent, the viscosity of the solution containing the decomposed polymer is low, indicating excellent post-decomposition processing performance. Furthermore, from a comparison of the examples, it can be seen that in a specific compound, A 1 and A 2 When they represent different structures (specifically, A 1 represents -CO-O-, A 2 -CO- or -CO-NR 3 - represents, or A 1 ga-CO-NR 3 - represents A 2 When A represents -CO-, it is clear that the oxidative decomposition time is further shortened (see comparison between Example 5 and Examples 6-8). Furthermore, in certain compounds, 1 represents -CO-O-, A 2 ga-CO-NR 3 When this is expressed as -, it can be seen that the oxidative decomposition time, water absorption amount, and post-decomposition treatment performance are all at an excellent level (see comparison between Example 6, Example 7, and Example 8).

Claims

1. A compound represented by the following general formula (1). 【Chemistry 1】 In general formula (1), A １ and A ２ These are, independently, -CO-, -CO-O-, and -CO-NR ３ -, -SO ２ -, or -SO ２ -NR ４ Represents -. R ３ and R ４ Each of these independently represents a hydrogen atom, an alkyl group, or an alkenyl group. R １ and R ２ each independently represents a group represented by any one of the following general formulas (2) to (6). 【Chemistry 2】 In general formula (2), R ５ represents a hydrogen atom or a methyl group. In general formula (3), R ６ represents a hydrogen atom or a methyl group. In general formula (4), R ７ L represents a hydrogen atom or a methyl group. １ This represents an alkylene group. In general formula (5), R ８ L represents a hydrogen atom or a methyl group. ２ This represents an alkylene group. In general formula (6), L ３ This represents an alkylene group. However, in general formula (1), A １ When -CO- represents, A ２ is -CO-O-, -CO-NR ３ -, -SO ２ -, or -SO ２ -NR ４ Represents -. A １ When -CO-O- represents, A ２ -CO-, -CO-NR ３ -, -SO ２ -, or -SO ２ -NR ４ Represents -. A １ ga-CO-NR ３ When representing -, R １ This represents a group represented by any of the general formulas (2), (3), (5), and (6). ２ ga-CO-NR ３ When representing -, R ２ This represents a group represented by any of the general formulas (2), (3), (5), and (6).

2. R １ and R ２ The compound according to claim 1, wherein each independently represents a group represented by general formula (2) or a group represented by general formula (3).

3. A １ However, -CO-O- or -CO-NR ３ - represents A ２ However, -CO- or -CO-NR ３ The compound according to claim 1, which represents -.

4. The compound according to claim 1, wherein the compound represented by the general formula (1) is a compound represented by any of the following formulas (1A) to (1D). 【Transformation 3】

5. An oxidatively degradable crosslinking agent comprising the compound described in claim 1.

6. A composition comprising the compound described in claim 1 and a radical polymerizable compound.

7. The composition according to claim 6, wherein the radical polymerizable compound comprises one or more selected from the group consisting of acrylic acid, methacrylic acid, vinyl sulfonic acid, acrylic acid ester, methacrylic acid ester, acrylamide, methacrylamide, N-vinylpyrrolidone, N-vinylformaldehyde, styrene, vinyl acetate, and maleimide.

8. The composition according to claim 7, wherein the radical polymerizable compound is acrylic acid or methacrylic acid.

9. A polymer comprising repeating units derived from a radical polymerizable compound and repeating units derived from a compound represented by the following general formula (1). 【Chemistry 4】 In general formula (1), A １ and A ２ These are, independently, -CO-, -CO-O-, and -CO-NR ３ -, -SO ２ -, or -SO ２ -NR ４ Represents -. R ３ and R ４ Each of these independently represents a hydrogen atom, an alkyl group, or an alkenyl group. R １ and R ２ Each of these independently represents a group that can be expressed by any of the following general formulas (2) to (6). 【Transformation 5】 In general formula (2), R ５ represents a hydrogen atom or a methyl group. In general formula (3), R ６ represents a hydrogen atom or a methyl group. In general formula (4), R ７ L represents a hydrogen atom or a methyl group. １ This represents an alkylene group. In general formula (5), R ８ L represents a hydrogen atom or a methyl group. ２ This represents an alkylene group. In general formula (6), L ３ This represents an alkylene group. However, in general formula (1), A １ When -CO- represents, A ２ is -CO-O-, -CO-NR ３ -, -SO ２ -, or -SO ２ -NR ４ Represents -. A １ When -CO-O- represents, A ２ -CO-, -CO-NR ３ -, -SO ２ -, or -SO ２ -NR ４ Represents -. A １ ga-CO-NR ３ When representing -, R １ This represents a group represented by any of the general formulas (2), (3), (5), and (6). ２ ga-CO-NR ３ When representing -, R ２ This represents a group represented by any of the general formulas (2), (3), (5), and (6).

10. R １ and R ２ The polymer according to claim 9, wherein each independently represents a group represented by the general formula (2) or a group represented by the general formula (3).

11. A １ However, -CO-O- or -CO-NR ３ - represents A ２ However, -CO- or -CO-NR ３ The polymer according to claim 9, which represents -.

12. The polymer according to claim 9, wherein the compound represented by the general formula (1) is a compound represented by any of the following formulas (1A) to (1D). 【Transformation 6】

13. A water-absorbing article comprising the polymer described in claim 9.

14. A method for decomposing a polymer, comprising contacting the polymer described in claim 9 with an oxidizing agent to decompose the polymer.

15. The method for decomposing a polymer according to claim 14, wherein the oxidizing agent is sodium hypochlorite.

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