Polymer, production method therefor, and composition, aqueous solution, molded body, and packaging containing polymer

Abstract

Provided are: a polymer (X) containing a structural unit (A) represented by general formula (1) and a structural unit (B) represented by general formula (2); a production method therefor; and a composition, aqueous solution, molded body, and packaging containing said polymer.

Description

Polymer, its manufacturing method, and composition, aqueous solution, molded article, and packaged article containing the polymer

[0001] The present invention relates to a polymer, a method for producing the same, and a composition, an aqueous solution, a molded article, and a packaged article containing the polymer.

[0002] Vinyl alcohol polymers have excellent film properties (mechanical strength, oil resistance, film-forming ability, oxygen gas barrier property, etc.) due to their hydrophilicity or high crystallinity. Taking advantage of these properties, vinyl alcohol polymers are therefore widely used as raw materials for viscosity modifiers (thickeners), adhesives, paper coating agents, fiber processing agents, binders, emulsion stabilizers, films, fibers, etc. Furthermore, in order to improve the performance of vinyl alcohol polymers according to their applications, modified vinyl alcohol polymers have been developed by introducing functional groups, controlling crystallinity, etc.

[0003] Since polyvinyl alcohol is a crystalline polymer, if its degree of saponification is too high, its solubility in water decreases. To address this issue, a method of reducing crystallinity by random copolymerizing vinyl esters with other monomers is known to ensure water solubility. Patent Document 1 describes a block copolymer consisting of a vinyl alcohol-based polymer block (B-b) and a copolymer block (B-c) containing vinyl alcohol-based monomer units and acrylic acid-based monomer units as a vinyl alcohol-based block copolymer having excellent water solubility, aqueous solution stability, and strength.

[0004] International Publication No. 2020 / 262517

[0005] Meanwhile, vinyl alcohol polymers are known as biodegradable materials, but according to studies by the present inventors, it has been found that biodegradability decreases when an acrylic acid monomer is copolymerized to increase water solubility, as in the technique of Patent Document 1. For this reason, it has been difficult to obtain a vinyl alcohol polymer that is both water soluble and biodegradable.

[0006] The present invention has an object of solving the above problems, and an object of the present invention is to provide a polymer that is highly water-soluble and biodegradable, a method for producing the same, and a composition, an aqueous solution, a molded article, and a packaged article that contain the polymer.

[0007] The present inventors have conducted studies to solve the above-mentioned problems and have found that the problems can be solved by the following embodiments [1] to

[17] : [1] A polymer (X) containing a structural unit (A) represented by the following general formula (1) and a structural unit (B) represented by the following general formula (2): (In formula (1), R １ represents a hydrogen atom, an amino group, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms. ２ represents a hydrogen atom, a metal atom, an ammonium group, a phosphonium group, or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. ３ represents a hydroxyl group or —O—C(═O)—R ４ R represents a group represented by the formula: ４ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. [2] R in the general formula (2) ３ is a hydroxyl group or —O—C(═O)—CH ３ [3] The polymer (X) according to the above [1], wherein R in the general formula (1) is １ [4] The polymer (X) according to the above [1] or [2], wherein R in the general formula (1) is a hydrogen atom or an allyl group. ２ is a hydrogen atom, an alkali metal atom, or a methyl group. [5] Polymer (X) according to any one of the above [1] to [4], further comprising an optional structural unit (C) represented by the following general formula (3), wherein the total content of the structural unit (A) and the optionally contained structural unit (C) is 0.01 to 20.0 mol % based on all monomer units (100 mol %) of the polymer (X): (R in the formula １ represents R in the general formula (1). １The polymer (X) is the same as the polymer (X) described in any one of [1] to [5] above, having a degree of saponification of 70.00 to 99.99 mol%. [7] The polymer (X) is the polymer (X) described in any one of [1] to [6] above, having a number-average degree of polymerization DPn of 100 to 5,000. [8] The polymer (X) is the polymer (X) described in any one of [1] to [7] above, further comprising a structural unit (C) represented by the following general formula (3), wherein the ratio of the molar content of the structural unit (A) to the total molar content of the structural unit (A) and the structural unit (C) [(structural unit (A)) / (structural unit (A)+structural unit (C))] is 0.01 to 0.99: (R in the formula １ represents R in the general formula (1). １ The same as above.) [9] A composition comprising the polymer (X) according to any one of [1] to [8] above.

[10] An aqueous solution comprising the polymer (X) according to any one of [1] to [8] above.

[11] A molded article comprising the polymer (X) according to any one of [1] to [8] above.

[12] The molded article according to

[11] above, which is a film.

[13] The molded article according to

[11] or

[12] above, which is water-soluble.

[14] A package comprising a chemical housed in the molded article according to

[12] or

[13] above.

[15] The package according to

[14] above, wherein the chemical is an agricultural chemical or a detergent.

[16] A method for producing the polymer (X) according to any one of [1] to [8] above, comprising the steps of copolymerizing a monomer (a) represented by the following general formula (I) with a monomer (b) represented by the following general formula (II) to obtain a copolymer, and saponifying the copolymer. (R in formula (I) １ and R ２ is R in the general formula (1). １ and R ２ and R in formula (II) is the same as ４ is R in the description of the general formula (2) ４

[17] A polymer (X') containing a structural unit (C) represented by the following general formula (3): (In formula (3), R １represents a hydrogen atom, an amino group, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms.

[0008] According to the present invention, it is possible to provide a polymer having excellent water solubility and biodegradability, a method for producing the same, and a composition, an aqueous solution, a molded article, and a packaged article containing the polymer.

[0009] An example of an embodiment to which the present invention is applied will be described below, but other embodiments are also included in the present invention as long as they are consistent with the spirit of the present invention.

[0010] [Polymer (X)] The polymer (X) of the present invention is a polymer containing a structural unit (A) represented by the following general formula (1) and a structural unit (B) represented by the following general formula (2).

[0011] (In formula (1), R １ represents a hydrogen atom, an amino group, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms. ２ represents a hydrogen atom, a metal atom, an ammonium group, a phosphonium group, or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. ３ represents a hydroxyl group or —O—C(═O)—R ４ R represents a group represented by the formula: ４ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms.

[0012] <Structural Unit (A)> The structural unit (A) contained in the polymer (X) of the present invention is represented by the above general formula (1). The polymer (X) may contain only one type of structural unit (A), or two or more types of structural units (A). It is believed that the polymer (X) of the present invention achieves both water solubility and biodegradability by containing the structural unit (A). This is due to the -C(=O)-OR structure of the structural unit (A). ２ The structural unit (A) contains a quaternary carbon that constitutes the main chain of the polymer (X) and is capable of forming a hydrogen bond. １ It is presumed that the presence of the group reduces the mobility of the molecule, making it more susceptible to attack by decomposing enzymes.

[0013] (R in general formula (1) １ R in the above general formula (1) １ represents a hydrogen atom, an amino group, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms. ２ -OR １ The group -CH ２ - group and -R １ An oxygen atom (—O—) bonded to both of the aryl and aryl groups may be referred to as “oxygen atom (1).” In the following description, a ring-forming atom refers to an atom constituting the ring itself in a structure in which atoms are bonded in a ring, and does not include atoms such as hydrogen atoms and substituents bonded to atoms constituting the ring.

[0014] In the present invention, R １ has a heterocyclic ring, and the atom bonded to the oxygen atom (1) is a ring-forming atom of the heterocyclic ring, １ In addition, when the heterocycle forms a condensed ring and the atom bonded to the oxygen atom (1) is a ring-forming atom of the condensed ring, the atom bonded to the oxygen atom (1) is classified as a heterocyclic group. １ is classified as a heterocyclic group. １ has a hydrocarbon group, and the atom bonded to the oxygen atom (1) is a carbon atom of the hydrocarbon group, １ is classified as a hydrocarbon group.

[0015] R in the above general formula (1) １ Examples of the substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms represented by R include a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, and a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms. １ has a fused ring other than a heterocycle, and the fused ring is formed from an aromatic ring and a non-aromatic ring, and the atom bonded to the oxygen atom (1) is a ring-forming atom of the aromatic ring constituting the fused ring, １is classified as an aromatic hydrocarbon group, and when the atom bonded to the oxygen atom (1) is a ring-forming atom of a non-aromatic ring constituting the above-mentioned fused ring, the R １ is classified as an alicyclic hydrocarbon group.

[0016] Examples of the substituent that the substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms may have include a hydroxy group, a halogen atom, a cyano group, a nitro group, a carboxy group, an amino group, a quaternary ammonium base, an alkoxy group, an aryloxy group, and an acyloxy group.

[0017] The number of carbon atoms excluding the substituent in the substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms is preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5. The number of carbon atoms including the substituent in the substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms is preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5. When the number of carbon atoms is equal to or less than the above upper limit, thickening of the polymer (X) is suppressed, improving the coatability during film formation and improving the productivity, thickness accuracy, etc. of the film.

[0018] The substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms may be linear, branched, or cyclic. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group or an unsaturated aliphatic hydrocarbon group. Examples of the substituent that the substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms may have include, in addition to those listed above, aromatic hydrocarbon groups, heterocyclic groups, and the like.

[0019] Examples of the substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms include a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, a substituted or unsubstituted branched unsaturated aliphatic hydrocarbon group having 3 to 20 carbon atoms, and a substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0020] Examples of the linear alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group.

[0021] Examples of branched alkyl groups having 3 to 20 carbon atoms include an isopropyl group (1-methylethyl group), a 1-methylpropyl group, a 2-methylpropyl group, a t-butyl group, a 1,1-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1,2-dimethylpropyl group, a 1-ethylpropyl group, a 2-ethylpropyl group, a 1,1-diethylpropyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1,1-dimethylbutyl group, a 2,2-dimethylbutyl group, a 3,3-dimethylbutyl group, a 1,3,3-trimethylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-propylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a 4,4-dimethylpentyl group, a 1-methylhexyl group, and a 2-methylhexyl group. , 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 5,5-dimethylhexyl group, 1-methylheptyl group, 2-methylheptyl group, 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 6-methylheptyl group, 6,6-dimethylheptyl group, 1-methyloctyl group, 2-methyloctyl group, 3-methyloctyl group, 4-methyloctyl group, 5 1-methyloctyl group, 6-methyloctyl group, 7-methyloctyl group, 7,7-dimethyloctyl group, 1-methylnonyl group, 2-methylnonyl group, 3-methylnonyl group, 4-methylnonyl group, 5-methylnonyl group, 6-methylnonyl group, 7-methylnonyl group, 8-methylnonyl group, 3,5,5-trimethylhexyl group, 3,7,11,15-tetramethylhexadecyl group, and the like.

[0022] Examples of the linear unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms include ethenyl (vinyl), propenyl (allyl), butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, and nonadecenyl groups. and icosenyl groups; linear alkynyl groups such as propynyl, butynyl, pentynyl, hexynyl, octynyl, and undecynyl groups; and linear unsaturated aliphatic hydrocarbon groups containing two or more unsaturated bonds such as heptadienyl, hexadienyl, octadienyl, nonadienyl, decadienyl, undecadienyl, and decatrienyl groups. In the linear unsaturated aliphatic hydrocarbon groups, the double bond or triple bond may be located at any position.

[0023] Examples of the branched unsaturated aliphatic hydrocarbon group having 3 to 20 carbon atoms include an isopropenyl group, a 1-methylpropenyl group, a 2-methylpropenyl group, a t-butenyl group, a 1,1-dimethylpropenyl group, a 2,2-dimethylpropenyl group, a 1,2-dimethylpropenyl group, a 1-ethylpropenyl group, a 2-ethylpropenyl group, a 1,1-diethylpropenyl group, a 1-methylbutenyl group, a 2-methylbutenyl group, and a 3-methyl-2-butenyl group. a 3-methyl-3-butenyl group, a 1,1-dimethylbutenyl group, a 2,2-dimethylbutenyl group, a 3,3-dimethylbutenyl group, a 1,3,3-trimethylbutenyl group, a 1-ethylbutenyl group, a 2-ethylbutenyl group, a 3,3-dimethylbutenyl group, a 1-propylbutenyl group, a 1-methylpentenyl group, a 2-methylpentenyl group, a 3-methylpentenyl group, a 4-methylpentenyl group, a 4,4-dimethylpent ... hexenyl group, 2-methylhexenyl group, 3-methylhexenyl group, 4-methylhexenyl group, 5-methylhexenyl group, 5,5-dimethylhexenyl group, 1-methylheptenyl group, 2-methylheptenyl group, 3-methylheptenyl group, 4-methylheptenyl group, 5-methylheptenyl group, 6-methylheptenyl group, 6,6-dimethylheptenyl group, 1-methyloctenyl group, 2-methyloctenyl group, 3-methyloctenyl group Examples of branched unsaturated aliphatic hydrocarbon groups include 1-methylnonenyl, 4-methyloctenyl, 5-methyloctenyl, 6-methyloctenyl, 7-methyloctenyl, 7,7-dimethyloctenyl, 1-methylnonenyl, 2-methylnonenyl, 3-methylnonenyl, 4-methylnonenyl, 5-methylnonenyl, 6-methylnonenyl, 7-methylnonenyl, 8-methylnonenyl, 1-ethenylnonyl, and 3,5,5-trimethylhexenyl. In the branched unsaturated aliphatic hydrocarbon groups, the double bond or triple bond may be located at any position.

[0024] Examples of the substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclohexen-1-yl group, a bicyclo[2.2.1]heptan-1-yl group, a 1,2,3,4-tetrahydro-1-naphthalenyl group, a 1,4-dioxaspiro[4.5]dec-8-yl group, a tricyclo[3.3.1.1] ３，７ ]dec-1-yl group and the like.

[0025] Examples of the substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a 1-naphthalenyl group, a 2-naphthalenyl group, a 5,6,7,8-tetrahydro-1-naphthalenyl group, a 2,3-dihydro-1H-inden-5-yl group, an anthracenyl group, a fluorenyl group, a phenanthrenyl group, a pyrenyl group, a tetracenyl group, etc. Examples of the substituent that the substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms may have include, in addition to the above-mentioned substituents, an aliphatic hydrocarbon group, a heterocyclic group, etc.

[0026] R in the above general formula (1) １ Examples of the substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms represented by the formula (I) include an oxetanyl group, a tetrahydro-3-furanyl group, a tetrahydro-2-furanyl group, a tetrahydro-2H-pyran-2-yl group, a tetrahydro-2H-pyran-4-yl group, a 1,3-benzodioxol-5-yl group, a tetrahydrothiophenium group, a silacyclohex-1-yl group, a 3-isothiazolyl group, a 3-pyridinyl group, a 1H-indol-4-yl group, a 3-quinolinyl group, a 5-quinolinyl group, a 7-quinolinyl group, an 8-quinolinyl group, etc. Examples of the substituent that the substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms can have include, in addition to the above-mentioned groups, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, etc.

[0027] Among the above options, R １From the viewpoints of water solubility and biodegradability, is preferably a hydrogen atom or a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, and even more preferably a hydrogen atom or an allyl group.

[0028] (R in general formula (1) ２ In the above general formula (1), R ２ represents a hydrogen atom, a metal atom, an ammonium group, a phosphonium group, or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. ２ Examples of the metal atom represented by R include alkali metal atoms such as lithium, sodium, and potassium; and alkaline earth metal atoms such as magnesium and calcium. ２ is a metal atom, an ammonium group, or a phosphonium group, -OR ２ represents a salt of an oxygen atom with a metal atom, an ammonium group, or a phosphonium group. ２ The substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms represented by R １ The structure exemplified is the same as that of the substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I).

[0029] Among the above options, R ２ From the viewpoint of water solubility and biodegradability, R is preferably a hydrogen atom, an alkali metal atom, or a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom, an alkali metal atom, or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, even more preferably a hydrogen atom, an alkali metal atom, or a methyl group, even more preferably an alkali metal atom, and particularly preferably sodium. ２The content of the structural unit (A) in which is an alkali metal atom is preferably 20 to 100 mol %, more preferably 50 to 100 mol %, even more preferably 70 to 100 mol %, still more preferably 90 to 100 mol %, and still more preferably 95 to 100 mol %, from the viewpoint of water solubility.

[0030] (Monomer (a) Providing Structural Unit (A)) The structural unit (A) is formed by polymerizing a monomer (a) represented by the following general formula (I).

[0031] (In the formula, R １ and R ２ is R in the above general formula (1). １ and R ２ is the same as

[0032] Examples of the monomer (a) include 2-(hydroxymethyl)methyl acrylate, 2-(allyloxymethyl)methyl acrylate, 2-(methoxymethyl)methyl acrylate, 2-(ethoxymethyl)methyl acrylate, 2-(propoxymethyl)methyl acrylate, 2-[(1-methylethoxy)methyl]methyl acrylate, 2-(n-butoxymethyl)methyl acrylate, 2-[[(3,7,11,15-tetramethylhexadecyl)oxy]methyl]methyl acrylate, 2-[(n-dodecyloxy)methyl]methyl acrylate, 2-[(n-hexadecyloxy)methyl]methyl acrylate, 2-[(3-buten-1-yloxy)methyl]methyl acrylate, 2-[[(2-methyl-2-propen-1-yl)oxy]methyl]methyl acrylate, 2 methyl 2-[(2-buten-1-yloxy)methyl]acrylate, methyl 2-[(1-ethenylnonyloxy)methyl]acrylate, methyl 2-[[(1,1-dimethyl-3-buten-1-yl)oxy]methyl]acrylate, methyl 2-[(3,5-hexadienyloxy)methyl]acrylate, methyl 2-[(2-propyn-1-yloxy)methyl]acrylate, methyl 2-[(2-pentyn-1-yloxy)methyl]acrylate, methyl 2-(hydroperoxymethyl)acrylate, methyl 2-[(1,4-dioxaspiro[4.5]dec-8-yloxy)methyl]acrylate, methyl 2-[(3-isothiazolyloxy)methyl]acrylate, methyl 2-[(5-quinolinyloxy)methyl]acrylate, 2-[(tricyclo[3.3.1.1 ３，７]dec-1-yloxy)methyl] methyl acrylate, 2-(phenoxymethyl) methyl acrylate, 2-[(cyclohexyloxy)methyl] methyl acrylate, 2-[(5,6,7,8-tetrahydro-1-naphthalenyloxy)methyl] methyl acrylate, 2-(n-butoxymethyl) butyl acrylate, 2-[(n-pentyloxy)methyl] ethyl acrylate, 2-[(n-hexyloxy)methyl] ethyl acrylate, 2-[(n-heptyloxy)methyl] ethyl acrylate, 2-[( 2-[(n-hexadecyloxy)methyl]ethyl acrylate, 2-[(n-octadecyloxy)methyl]ethyl acrylate, 2-[(10-undecyn-1-yloxy)methyl]ethyl acrylate, 2-[(2-heptyn-1-yloxy)methyl]ethyl acrylate, 2-[(1-methylethoxy)methyl]ethyl acrylate, 2-[(1-methylpropoxy)methyl]ethyl acrylate, 2-[(3-methylbutoxy)methyl]ethyl acrylate, 2-[(1-methylbutoxy)methyl]ethyl acrylate ethyl, 2-[(1-ethylpropoxy)methyl]ethyl acrylate, 2-[(aminooxy)methyl]ethyl acrylate, 2-[(2-propen-1-yloxy)methyl]ethyl acrylate, 2-[(3-buten-1-yloxy)methyl]ethyl acrylate, 2-[(4-penten-1-yloxy)methyl]ethyl acrylate, 2-[(cyclopropyloxy)methyl]ethyl acrylate, 2-[(cyclobutyloxy)methyl]ethyl acrylate, 2-[(cyclopentyloxy)methyl]acrylate Ethyl acrylate, 2-[(cycloheptyloxy)acrylate, 2-[(1-cyclohexen-1-yloxy)methyl]acrylate, 2-[[(2,3-dihydro-1H-inden-5-yl)oxy]methyl]acrylate, 2-[[(5,6,7,8-tetrahydro-2-naphthalenyl)oxy]methyl]acrylate, 2-[(2-naphthalenyloxy)methyl]acrylate, 2-[(1-naphthalenyloxy)methyl]acrylate, 2-[[(1,2,3,4-tetrahydro-1-naphthalenyl)oxy]methyl]ethyl acrylate, 2-[(3-oxetanyloxy)methyl]ethyl acrylate, 2-[[(tetrahydro-3-furanyl)oxy]methyl]ethyl acrylate, 2-[(2-propen-yloxy)methyl]tetrahydro-2-furanyl acrylate, 2-[[(tetrahydro-2H-pyran-2-yl)oxy]methyl]ethyl acrylate, 2-[[(tetrahydro-2H-pyran-4-yl)oxy]methyl]ethyl acrylate, 2-[(1,3-benzodioxol-5-yloxy)methyl]ethyl acrylate, 1-[[2-(ethoxycarbonyl)-2-propen-1-yl]oxy]tetrahydrothiophenium, 2-[(3-isothiazolyloxy)methyl]methyl acrylate, 2-[(silacyclohex-1-yloxy)methyl]acrylate 1-methylethyl, 1-[[2-(ethoxycarbonyl)-2-propen-1-yl]oxy]pyridinium, 2-[(3-pyridinyloxy)methyl]acrylate 2-[(1H-indol-4-yloxy)methyl]ethyl acrylate, 2-[(7-quinolinyloxy)methyl]ethyl acrylate, 2-[(3-quinolinyloxy)methyl]ethyl acrylate, 2-[(8-quinolinyloxy)methyl]ethyl acrylate, 2-[(5-quinolinyloxy)methyl]ethyl acrylate, 1-[[2-(ethoxycarbonyl)-2-propen-1-yl]oxy)] Quinolinium, tris[2-[(2-propen-1-yloxy-κO)methyl]-2-propenoato-κO]europium, bis[2-[(2-propen-1-yloxy-κO)methyl]-2-propenoato-κO]manganese, [2-[(2-propen-1-yloxy-κO)methyl]-2-propenoato-κO]silver, bis[2-[(2-propen-1-yloxy-κO)methyl]-2-propenoato-κO]zinc, tris[2-[(2 Examples of suitable monomers include lanthanum [2-[[(2-methyl-2-propen-1-yl)oxy-κO]methyl]-2-propenoato-κO], tris[2-[[(2-methyl-2-propen-1-yl)oxy-κO]methyl]-2-propenoato-κO], zinc, bis[2-[[(2-methyl-2-propen-1-yl)oxy-κO]methyl]-2-propenoato-κO], and bis[2-[(2-propen-1-yloxy-κO)methyl]-2-propenoato-κO]cobalt. Among these, methyl 2-(hydroxymethyl)acrylate and methyl 2-(allyloxymethyl)acrylate are preferred from the viewpoints of water solubility and biodegradability. Monomer (a) may be used singly or in combination of two or more.

[0033] <Structural Unit (B)> The structural unit (B) contained in the polymer (X) of the present invention is represented by the above general formula (2). The polymer (X) may contain only one type of structural unit (B), or may contain two or more types of structural units (B).

[0034] (R in general formula (2) ３ R in the above general formula (2) ３ represents a hydroxyl group or —O—C(═O)—R ４ It is a group represented by the formula: —O—C(═O)—R ４ R of a group represented by ４ The substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms represented by R １ The structures exemplified are the same as those of the substituted or unsubstituted hydrocarbon groups having 1 to 20 carbon atoms represented by R ４ is preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a substituted or unsubstituted unsaturated aliphatic hydrocarbon group having 2 to 20 carbon atoms, more preferably a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, further preferably an ethyl group or a methyl group, and particularly preferably a methyl group.

[0035] Among the above options, R ３ From the viewpoints of industrial and water solubility, it is preferable that the compound has a hydroxyl group or -O-C(=O)-CH ３ R is preferably a hydroxyl group, and more preferably a hydroxyl group. ３ From the viewpoint of water solubility, the content of the structural unit (B) in which is a hydroxyl group is preferably 70.00 to 99.99 mol%, more preferably 75.00 to 99.00 mol%, even more preferably 80.00 to 98.00 mol%, still more preferably 85.00 to 97.00 mol%, and still more preferably 88.00 to 96.00 mol%.

[0036] (Monomer (b) Providing Structural Unit (B)) The structural unit (B) is formed by polymerizing a monomer (b) represented by the following general formula (II).

[0037] (R in the formula ４ is R in the description of the general formula (2)４ is the same as

[0038] Examples of the monomer (b) include vinyl acetate, vinyl formate, vinyl propionate, vinyl caprylate, and vinyl versatate. Among these, vinyl acetate is preferred from an industrial viewpoint. The monomer (b) may be used alone or in combination of two or more.

[0039] <Structural Unit (C)> The polymer (X) of the present invention may further contain a structural unit (C) represented by the following general formula (3): The polymer (X) may contain only one type of structural unit (C), or may contain two or more types of structural units (C).

[0040] (R in the formula １ represents R in the general formula (1). １ is the same as

[0041] The structural unit (C) corresponds to a structure in which, when the monomer (a) and the monomer (b) are copolymerized and the resulting copolymer is saponified, the structural unit (A) derived from the monomer (a) and the structural unit (B) derived from the monomer (b) adjacent to the structural unit (A) form a lactone ring. The inclusion of the structural unit (C) in the polymer (X) prevents the surface of the polymer (X) from melting and adhering to form clumps, which would otherwise make the polymer (X) less soluble in water. As described above, the polymer (X) of the present invention contains the structural unit (A) and the structural unit (B). The present invention also provides a polymer (X') containing the structural unit (C), which corresponds to a precursor of the polymer (X).

[0042] <Other Structural Units> The polymer (X) of the present invention may or may not contain other structural units (hereinafter simply referred to as "other structural units") in addition to the above structural units.Examples of other structural units include structural units derived from ethylenically unsaturated monomers other than the monomer (a) and the monomer (b). Examples of the ethylenically unsaturated monomers include α-olefins such as ethylene, propylene, n-butene, and isobutylene; acrylates such as acrylic acid and its salts, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate; esters; methacrylic acid and its salts; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate; acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidopropanesulfonic acid and its salts, acrylamide propanesulfonic acid, and the like; acrylamide derivatives such as propyldimethylamine and its salts or quaternary salts thereof, and N-methylolacrylamide and its derivatives; methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidepropyldimethylamine and its salts or quaternary salts thereof, and N-methylolmethacrylamide and its derivatives; methacrylamide derivatives such as methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidepropyldimethylamine and its salts or quaternary salts thereof, and N-methylolmethacrylamide and its derivatives; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether vinyl ethers such as butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride and vinyl fluoride; vinyl halides such as vinylidene chloride and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; unsaturated dicarboxylic acids and salts or esters thereof such as maleic acid, itaconic acid, and fumaric acid; vinyl silyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate.

[0043] The polymer (X) of the present embodiment may further contain a structural unit represented by the following general formula (4).

[0044] (In the formula, R ２ represents R in the general formula (1). ２ It is the same as R ５ represents a substituted or unsubstituted trivalent hydrocarbon group having 1 to 20 carbon atoms.

[0045] The number of carbon atoms, excluding substituents, of the substituted or unsubstituted trivalent hydrocarbon group having 1 to 20 carbon atoms is preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5. The number of carbon atoms, including substituents, of the substituted or unsubstituted trivalent hydrocarbon group having 1 to 20 carbon atoms is preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5. As the substituted or unsubstituted trivalent hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted trivalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms is preferred, and a substituted or unsubstituted trivalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms is more preferred.

[0046] R in the above general formula (4) ５ Examples of the substituent that the substituted or unsubstituted trivalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) may have include a hydroxy group, a halogen atom, a cyano group, a nitro group, a carboxy group, an amino group, a quaternary ammonium base, an alkoxy group, an aryloxy group, and an acyloxy group.

[0047] Examples of the substituted or unsubstituted trivalent hydrocarbon group having 1 to 20 carbon atoms include alkanetriyl groups such as methanetriyl group, ethanetriyl group, 1,2,3-propanetriyl group, 1,2,4-butanetriyl group, 1,2,5-pentanetriyl group, 1,3,5-pentanetriyl group, 1,2,6-hexanetriyl group, and 1,3,6-hexanetriyl group; and arenetriyl groups such as 1,2,3-benzenetriyl group, 1,2,4-benzenetriyl group, and 1,3,5-benzenetriyl group.

[0048] The structural unit represented by the above general formula (4) is preferably a structural unit represented by the following formula (4') from the viewpoint of productivity.

[0049] (In the formula, R ２ represents R in the general formula (1). ２ is the same as

[0050] The structural unit represented by the general formula (4) is a structural unit that can be formed by polymerizing the above-mentioned monomer (a) while an intramolecular cyclization reaction occurs. Specifically, for example, R １ is a group containing an ethylenically unsaturated bond, R １ The structural unit represented by the general formula (4) can be formed by polymerization proceeding while an addition reaction occurs between the group containing an ethylenically unsaturated bond of the formula and the carbon at the 2-position shown in the formula below.

[0051] (In the formula, R １ and R ２ is as described above.)

[0052] R １ The group containing an ethylenically unsaturated bond represented by the formula (I) includes the above-mentioned R １ Among the options, a linear alkenyl group having 1 to 20 carbon atoms is preferred, and an allyl group is more preferred.

[0053] <Content of Each Structural Unit> The content of the structural unit (A) in the polymer (X) of the present invention is preferably 0.01 to 20.0 mol%, more preferably 0.01 to 15.0 mol%, even more preferably 0.01 to 10.0 mol%, even more preferably 0.01 to 8.0 mol%, even more preferably 0.01 to 7.0 mol%, even more preferably 0.01 to 5.0 mol%, and even more preferably 0.01 to 4.0 mol%, based on the total monomer units (100 mol%) of the polymer (X). When the content of the structural unit (A) is within the above range, the polymer (X) tends to be able to achieve both water solubility and biodegradability to a higher degree. In the present invention, the content of each structural unit in the total monomer units (100 mol%) of the polymer (X) can be measured by the method described in the Examples. Furthermore, the above-mentioned "total monomer units of polymer (X)" refers to the total number of all monomer units contained in polymer (X), when a structural unit based on one monomer molecule formed by polymerization of one monomer molecule is defined as a "monomer unit."

[0054] The content of the structural unit (B) in the polymer (X) of the present invention is preferably 50.0 to 99.9 mol%, more preferably 60.0 to 99.8 mol%, even more preferably 70.0 to 99.6 mol%, still more preferably 80.0 to 99.4 mol%, even more preferably 85.0 to 99.2 mol%, even more preferably 87.0 to 99.0 mol%, even more preferably 88.0 to 98.0 mol%, and even more preferably 90.0 to 97.0 mol% of the total monomer units (100 mol%) of the polymer (X). When the total content of the structural unit (B) is within the above range, the polymer (X) tends to be able to achieve a higher degree of both water solubility and biodegradability.

[0055] The total content of the structural unit (A) and the optionally contained structural unit (C) in the polymer (X) of the present invention [structural unit (A) + structural unit (C)] is preferably 0.01 to 20.0 mol%, more preferably 0.01 to 15.0 mol%, even more preferably 0.01 to 10.0 mol%, even more preferably 0.1 to 9.0 mol%, even more preferably 1.0 to 8.0 mol%, even more preferably 3.0 to 6.0 mol%, and even more preferably 4.0 to 5.0 mol% of the total monomer units (100 mol%) of the polymer (X). When the total content of the structural unit (A) and the optionally contained structural unit (C) is within the above range, the polymer (X) tends to be able to achieve a higher level of both water solubility and biodegradability. The above "total content of the structural unit (A) and the optionally contained structural unit (C)" means the "content of the structural unit (A)" when the polymer (X) does not contain the structural unit (C).

[0056] The total content of the structural unit (B) and optionally contained structural unit (C) in the polymer (X) of the present invention [structural unit (B) + structural unit (C)] is preferably 50.0 to 99.9 mol%, more preferably 60.0 to 99.8 mol%, even more preferably 70.0 to 99.6 mol%, even more preferably 80.0 to 99.4 mol%, even more preferably 90.0 to 99.2 mol%, even more preferably 92.0 to 99.0 mol%, even more preferably 94.0 to 98.5 mol%, and even more preferably 95.0 to 98.0 mol% of all monomer units (100 mol%) of the polymer (X). When the total content of the structural unit (B) and optionally contained structural unit (C) is within the above range, the polymer (X) tends to be able to achieve a higher degree of both water solubility and biodegradability. The above "total content of the structural unit (B) and the optionally contained structural unit (C)" means the "content of the structural unit (B)" when the polymer (X) does not contain the structural unit (C).

[0057] When the polymer (X) of the present invention contains the structural unit (C), the ratio of the molar content of the structural unit (A) to the total molar content of the structural units (A) and (C) [structural unit (A) / (structural unit (A)+structural unit (C)] is preferably 0.01 to 0.99, more preferably 0.05 to 0.99, even more preferably 0.05 to 0.90, still more preferably 0.10 to 0.90, even more preferably 0.10 to 0.80, still more preferably 0.10 to 0.70, still more preferably 0.15 to 0.70, and still more preferably 0.20 to 0.60. When the ratio [(structural unit (A)) / (structural unit (A)+structural unit (C)]] is within the above range, the polymer (X) tends to be able to achieve both water solubility and biodegradability to a higher degree.

[0058] In the polymer (X) of the present invention, the sum of the above-mentioned total content [structural unit (A) + structural unit (C)] and the above-mentioned total content [structural unit (B) + structural unit (C)] is, from the viewpoints of water solubility and biodegradability, preferably 70.0 to 100.0 mol%, more preferably 80.0 to 100.0 mol%, even more preferably 90.0 to 100.0 mol%, still more preferably 95.0 to 100.0 mol%, and particularly preferably 99.0 to 100.0 mol%.

[0059] <Saponification Degree> The saponification degree of the polymer (X) of the present invention is preferably 70.00 to 99.99 mol%, more preferably 80.00 to 99.00 mol%, even more preferably 85.00 to 98.00 mol%, still more preferably 86.00 to 97.00 mol%, and even more preferably 88.00 to 96.00 mol%. When the saponification degree is equal to or greater than the lower limit, the mechanical strength tends to be improved, and when it is equal to or less than the upper limit, the water solubility tends to be further improved. In the present invention, the saponification degree means the proportion (mol %) of saponified structural units among all structural units derived from vinyl ester-based monomers in the polymer (X). The above-mentioned "vinyl ester-based monomer" refers to a vinyl carboxylate (CH ２=CH-O-C(=O)-R, where R is a hydrocarbon group), and is typically the above-mentioned monomer (b), but may also contain monomers other than monomer (b). The "total structural units derived from vinyl ester monomers" used in calculating the degree of saponification refers to structural units derived from vinyl ester monomers that are not saponified and still have an acyloxy group (-O-C(=O)-R) (hereinafter also referred to as "vinyl ester units"). In particular, -O-C(=O)-CH ３ A structural unit that still has the formula (I) is also referred to as a "vinyl acetate unit." Examples of such structural units include a structural unit in which an acyloxy group is converted to a hydroxyl group (—OH) by saponification (hereinafter also referred to as a "vinyl alcohol unit"), and a structural unit that forms a lactone ring by saponification (hereinafter also referred to as a "lactone ring unit"). Furthermore, the "saponified structural unit" used in calculating the degree of saponification refers to a structural unit derived from a vinyl ester monomer in which an acyloxy group is converted to a hydroxyl group by saponification (hereinafter also referred to as a "vinyl alcohol unit"), a structural unit that forms a lactone ring by saponification, and the like. The degree of saponification of polymer (X) can be measured by the method described in the Examples.

[0060] <Number-average degree of polymerization DPn> The number-average degree of polymerization DPn of the polymer (X) of the present invention is preferably 100 to 5,000, more preferably 200 to 4,000, even more preferably 500 to 3,000, still more preferably 800 to 2,000, and particularly preferably 1,200 to 1,700. When the number-average degree of polymerization DPn of the polymer (X) is equal to or greater than the lower limit, the polymer (X) tends to have excellent mechanical strength, and when it is equal to or less than the upper limit, the polymer (X) tends to be easily produced industrially. The number-average degree of polymerization DPn of the polymer (X) can be measured by the method described in the examples.

[0061] <Biodegradability> From the viewpoint of biodegradability, the biodegradability of the polymer (X) of the present invention is preferably 38% or more, more preferably 40% or more, even more preferably 45% or more, and even more preferably 50% or more. The upper limit of the biodegradability is not particularly limited, but may be 100% or less, or may be 95% or less. The biodegradability can be measured by the method described in the Examples.

[0062] [Method for producing polymer (X)] The method for producing polymer (X) of the present invention is not particularly limited. For example, the method for producing polymer (X) of the present invention is simple and preferable, and includes a step of copolymerizing monomer (a) represented by general formula (I) above with monomer (b) represented by general formula (II) above to obtain a copolymer (hereinafter also referred to as a "polymerization step"), and a step of saponifying the copolymer (hereinafter also referred to as a "saponification step").

[0063] (Polymerization step) The explanation of the monomer (a) and the monomer (b) used in the polymerization step is the same as that of the structural unit (A) and the structural unit (B). The polymerization method for copolymerizing the monomer (a) and the monomer (b) may be any method such as batch polymerization, semi-batch polymerization, continuous polymerization, semi-continuous polymerization, etc., and known methods such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, and dispersion polymerization can be applied as the polymerization method. From an industrial viewpoint, solution polymerization, emulsion polymerization, and dispersion polymerization are preferred. The organic solvent used in the polymerization step is not particularly limited, and examples thereof include esters such as methyl acetate and ethyl acetate; aromatic hydrocarbons such as toluene; lower alcohols such as methanol and ethanol; and the like. Among these, from the viewpoint of cost, lower alcohols are preferred, and methanol is more preferred. The amount of solvent used in the polymerization system may be selected depending on the average degree of polymerization of the target polymer, taking into consideration chain transfer of the solvent. For example, when the solvent is methanol, the mass ratio of the solvent to the total monomers contained in the polymerization system {(solvent) / (total monomers)} is preferably in the range of 0.01 to 10, more preferably in the range of 0.05 to 3.

[0064] The polymerization initiator used in the copolymerization of the monomer (a) and the monomer (b) is not particularly limited and may be selected from known polymerization initiators such as azo initiators, peroxide initiators, redox initiators, etc., depending on the polymerization method. Examples of azo initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "V-70"). Examples of peroxide initiators include percarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; perester compounds such as t-butyl peroxyneodecanate, α-cumyl peroxyneodecanate, and t-butyl peroxyneodecanate; acetylcyclohexylsulfonyl peroxide; diisobutyryl peroxide; and 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate. These initiators may also be combined with potassium persulfate, ammonium persulfate, hydrogen peroxide, or the like to form peroxide initiators. Examples of redox initiators include combinations of the above peroxide initiators with reducing agents such as sodium hydrogen sulfite, sodium hydrogen carbonate, tartaric acid, L-ascorbic acid, and Rongalit. Among these, azo-based initiators are preferred, and 2,2'-azobisisobutyronitrile is more preferred from the viewpoints of polymerization at relatively low temperatures and suppressing side reactions. The amount of polymerization initiator used cannot be determined in general because it differs depending on the polymerization catalyst, but it is preferable to select it depending on the polymerization rate. The amount of polymerization initiator added is preferably 0.001 to 1.0 part by mass, more preferably 0.003 to 0.1 part by mass, and even more preferably 0.005 to 0.05 part by mass relative to the total amount (100 parts by mass) of the raw material monomers of polymer (X).

[0065] When polymerizing the monomer (a) and the monomer (b) in the polymerization step, the polymerization may be carried out in the presence of a chain transfer agent, as long as the effects of the present disclosure can be obtained. Examples of chain transfer agents include aldehydes such as formaldehyde, acetaldehyde, and propionaldehyde; ketones such as acetone and methyl ethyl ketone; mercaptans such as 2-hydroxyethanethiol; and phosphinates such as sodium phosphinate monohydrate. Among these, aldehydes and ketones are preferably used. The amount of chain transfer agent added to the polymerization system is determined depending on the chain transfer coefficient of the chain transfer agent added and the degree of polymerization of the desired copolymer, and may be, for example, 1 to 1,000,000 ppm by mass, 5 to 80,000 ppm by mass, or 10 to 60,000 ppm by mass relative to the total amount of raw material monomers for polymer (X).

[0066] The polymerization temperature is not particularly limited, but may be 0 to 150°C, preferably 0 to 80°C, more preferably 10 to 80°C, even more preferably 20 to 80°C, still more preferably 40 to 75°C, and even more preferably 50 to 70°C. When the polymerization temperature is 0°C or higher, the polymerization rate becomes sufficient and productivity improves. On the other hand, when the polymerization temperature is 150°C or lower, a polymer (X) having a narrow molecular weight distribution can be obtained.

[0067] Although the monomers (a) and (b) may be added all at once or successively, it is preferred to mix a part of the monomer (a) with the whole of the monomer (b) before starting the polymerization reaction, and then successively add the remaining monomer (a). This makes it possible to maintain a constant monomer composition in the polymerization solution, and facilitates the production of a polymer (X) having a desired composition.

[0068] When the target polymerization rate is reached, the polymerization reaction is terminated by rapidly cooling the reaction system, adding a polymerization terminator, or both simultaneously. Rapid cooling of the reaction system can be achieved by running cooling water through the reactor jacket, but adding a pre-cooled liquid medium to the reactor is preferred. The copolymer before saponification is obtained by the above method.

[0069] (Saponification Step) Saponification is preferably carried out in a state where the copolymer before saponification is dissolved in alcohol or aqueous alcohol. Examples of alcohols used in the saponification reaction include lower alcohols such as methanol and ethanol, with methanol being preferred. The alcohol used in the saponification reaction may or may not contain other solvents such as acetone, esters such as methyl acetate and ethyl acetate, and toluene. The content of other solvents is preferably 40% by mass or less, more preferably 10% by mass or less, based on the total amount of alcohol and other solvents. The concentration of the alcohol solution of the copolymer before saponification is preferably 1 to 50% by mass, more preferably 5 to 45% by mass, and even more preferably 8 to 40% by mass. Examples of catalysts used in the saponification reaction include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali catalysts such as sodium methylate, and acid catalysts such as mineral acids and organic acids. Among these, sodium hydroxide is preferred from the viewpoint of easy handling.

[0070] The temperature at which the saponification reaction is carried out is not limited, but is preferably 20 to 70°C, for example. At a temperature of 20°C or higher, the saponification reaction can proceed quickly. If a gel-like product precipitates as the saponification proceeds, the product can be pulverized, washed, and dried to obtain the saponified copolymer. The saponification method is not limited to the method described above, and any known method can be used.

[0071] When the lactone ring described above is formed in the copolymer after saponification, the copolymer may be treated with an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, whereby saponification and ring-opening of the lactone ring are carried out, thereby adjusting the degree of saponification and the content ratio of the structural unit (C).

[0072] [Aqueous Solution, Composition] The aqueous solution of the present invention is an aqueous solution containing the polymer (X) of the present invention. The content of the polymer (X) in the aqueous solution of the present invention is preferably 0.1 to 50.0 mass%, more preferably 1.0 to 40.0 mass%, even more preferably 5.0 to 35.0 mass%, and still more preferably 10.0 to 30.0 mass%. The aqueous solution of the present invention may contain components other than the polymer (X) and water, as long as the gist of the present invention is not impaired. Examples of components other than the polymer (X) and water include the same as the other components that may be contained in the molded article of the present invention, which will be described later.

[0073] The composition of the present invention is a composition containing the polymer (X) of the present invention. The composition of the present invention is not particularly limited as long as it contains the polymer (X) of the present invention and components other than the polymer (X) and the solvent. Examples of the components other than the polymer (X) and the solvent include the same components that may be contained in the molded article of the present invention described below.

[0074] The aqueous solutions and compositions of the present invention can be used in a variety of applications, including, but not limited to, the following examples. (1) Dispersant uses: Dispersion stabilizers for organic and inorganic pigments in paints, adhesives, etc.; Dispersion stabilizers and dispersion aids for suspension polymerization of various vinyl compounds such as vinyl chloride, vinylidene chloride, styrene, (meth)acrylate, and vinyl acetate. (2) Coating agent uses: Paper coating agents, sizing agents, fiber processing agents, leather finishing agents, paints, anti-fogging agents, metal corrosion inhibitors, zinc plating gloss agents, antistatic agents. (3) Adhesive uses: Adhesives, pressure sensitive adhesives, re-moistened adhesives, various binders, additives for cement and mortar. (4) Emulsifier uses: Emulsifier for emulsion polymerization, post-emulsifier for bitumen, etc. (5) Flocculant uses: Flocculant for suspended and dissolved substances in water, metal flocculant. (6) Paper processing uses: Paper strength enhancers, oil and solvent resistance agents, smoothness improvers, surface gloss improvement aids, sealing agents, barrier agents, light resistance agents, water resistance agents, dispersants for dyes and color developers, adhesion improvers, binders. (7) Agricultural uses: pesticide binders, pesticide spreaders, agricultural covering agents, soil conditioners, erosion inhibitors, pesticide dispersants (8) Medical and cosmetic uses: granulating binders, coating agents, emulsifiers, patches, binders, film formulation base materials, film formers (9) Viscosity adjuster uses: thickeners, rheology adjusters (10) Film uses: water-soluble films, polarizing films, barrier films, textile packaging films, seed protection sheets, vegetation sheets, seed tapes, moisture-absorbing films (11) Molded products uses: fibers, pipes, tubes, leak-proof films, water-soluble fibers for chemical lace, sponges (12) Gel uses: pharmaceutical gels, industrial gels (13) Post-reaction uses: post-reaction uses with low-molecular-weight organic compounds, high-molecular-weight organic compounds, and inorganic compounds

[0075] [Molded Article] The molded article of the present invention is a molded article containing the polymer (X) of the present invention. The shape of the molded article of the present invention is not particularly limited, and examples thereof include any shape such as a fiber, a film, a sheet, a tube, or a bottle. The method for molding the molded article of the present invention is not particularly limited, and examples thereof include a method of molding the polymer (X) of the present invention from a solution state in which the polymer (X) is dissolved in water, dimethyl sulfoxide, or the like (e.g., cast molding); and a method of plasticizing the polymer (X) by heating and molding it (e.g., extrusion molding, injection molding, inflation molding, press molding, blow molding).

[0076] The content of polymer (X) in the molded article of the present invention can be set arbitrarily depending on the physical properties required for the molded article. For example, from the viewpoint of the strength of the molded article, the content of polymer (X) is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 50% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the mass (100% by mass) of the molded article, and may be substantially 100% by mass.

[0077] The molded article of the present invention may further contain, as necessary, components other than the polymer (X) (hereinafter also referred to as "other components"). Examples of other components include polymers other than the polymer (X); plasticizers, surfactants, sugars, inorganic fillers, antioxidants, lubricants, release agents, antifoaming agents, anti-pestants, fillers, crosslinking agents, UV absorbers, processing stabilizers, antistatic agents, flame retardants, light stabilizers, release agents, preservatives, fragrances, deodorizers, extenders, rust inhibitors, weathering stabilizers, colorants, reinforcing agents, mildew inhibitors, crystallization rate retarders, compatibilizers, lubricants, bleaching agents (sodium bisulfite, sodium pyrosulfite), and other additives. These components may be used alone or in combination of two or more.

[0078] The plasticizer is not particularly limited as long as it is one that is commonly used as a plasticizer, and examples thereof include polyhydric alcohols such as glycerin, diglycerin, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, pentaerythritol, 1,3-butanediol, etc.; polyethers such as polyethylene glycol and polypropylene glycol; polyvinylamides such as polyvinylpyrrolidone; amide compounds such as N-methylpyrrolidone and dimethylacetamide; compounds in which ethylene oxide is added to polyhydric alcohols such as glycerin, pentaerythritol, sorbitol, etc., and water. These may be used alone or in combination. Among these plasticizers, glycerin, diglycerin, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, polyethylene glycol, and polyvinylpyrrolidone are preferred for the purpose of improving water solubility, and glycerin, diglycerin, trimethylolpropane, polyethylene glycol, and polyvinylpyrrolidone are particularly preferred from the standpoint of the effect of suppressing a decrease in water solubility of the film due to bleed-out of the plasticizer.

[0079] There is no particular restriction on the molecular weight of the polyethylene glycol used as the plasticizer, but from the viewpoints of compatibility with the polymer (X) and the effect of suppressing a decrease in water solubility due to bleed-out, the number average molecular weight is preferably 100 to 1,000. There is no particular restriction on the molecular weight of the polyvinylpyrrolidone used as the plasticizer, but from the viewpoint of compatibility with the polymer (X), the mass average molecular weight is preferably 1,000 to 20,000.

[0080] The blending amount of the plasticizer is preferably 1 to 50 parts by mass per 100 parts by mass of polymer (X). When the blending amount of the plasticizer is 1 part by mass or more, the effect of blending the plasticizer is fully exhibited. On the other hand, when the blending amount of the plasticizer is 50 parts by mass or less, bleed-out of the plasticizer can be suppressed. Furthermore, from the viewpoint of the dissolution rate of the obtained molded body in water, the blending amount of the plasticizer is more preferably 20 parts by mass or more per 100 parts by mass of polymer (X). On the other hand, from the viewpoint of the stiffness of the obtained molded body (the processability in a bag making machine, etc.), the blending amount of the plasticizer is more preferably 40 parts by mass or less per 100 parts by mass of polymer (X).

[0081] The type of surfactant is not particularly limited, but anionic or nonionic surfactants are preferred. Suitable anionic surfactants include, for example, carboxylic acid-type surfactants such as potassium laurate; sulfate-type surfactants such as octyl sulfate; and sulfonic acid-type surfactants such as dodecylbenzenesulfonate. Suitable nonionic surfactants include, for example, alkyl ether-type surfactants such as polyoxyethylene lauryl ether and polyoxyethylene oleyl ether; alkyl phenyl ether-type surfactants such as polyoxyethylene octylphenyl ether; alkyl ester-type surfactants such as polyoxyethylene laurate; alkyl amine-type surfactants such as polyoxyethylene lauryl amino ether; alkyl amide-type surfactants such as polyoxyethylene lauric acid amide; polypropylene glycol ether-type surfactants such as polyoxyethylene polyoxypropylene ether; alkanolamide-type surfactants such as oleic acid diethanolamide; and allyl phenyl ether-type surfactants such as polyoxyalkylene allyl phenyl ether. These surfactants can be used alone or in combination of two or more.

[0082] The amount of surfactant blended is preferably 0.01 to 2 parts by mass, more preferably 0.1 to 1 part by mass, and even more preferably 0.2 to 0.5 parts by mass, relative to 100 parts by mass of polymer (X). When the amount of surfactant blended is 0.01 part by mass or more, the peelability between the formed film and the metal surface of the drum or the like of the film-forming apparatus is improved, thereby improving productivity. When the amount of surfactant blended is 2 parts by mass or less, elution of the surfactant on the film surface can be suppressed.

[0083] Examples of sugars include monosaccharides, oligosaccharides, polysaccharides, and linear sugar alcohols. Examples of monosaccharides include glucose. Examples of oligosaccharides include galactooligosaccharides, isomaltooligosaccharides, xylooligosaccharides, soybean oligosaccharides, nigerooligosaccharides, lactoferrin oligosaccharides, and fructooligosaccharides. Examples of polysaccharides include starch, cellulose, chitin, chitosan, hemicellulose, pectin, pullulan, agar, alginic acid, carrageenan, dextrin, and trehalose. Examples of linear sugar alcohols include tetrites having four carbon atoms, such as threitol and erythritol; pentites having five carbon atoms, such as arabitol and xylitol; and hexites having six carbon atoms, such as glycite, mannitol, and sorbitol. These may be used alone or in combination. The addition of sugars can further improve the water solubility and biodegradability of the molded body, increase borate ion resistance, and suppress a decrease in cold water solubility after packaging chemicals, particularly chemicals that degrade polymers (chlorine-based substances, etc.). Among sugars, starch is preferred because of the good cold water solubility of the film when sugars are added. Examples of starch that can be used include raw starch from corn, potato, etc., and processed starches (dextrin, oxidized starch, etherified starch, cationized starch, etc.) that have been physically or chemically treated.

[0084] The molded article of the present invention can further contain an inorganic filler, if necessary. Examples of inorganic fillers that can be used in the molded article of the present invention include silica, heavy, light, or surface-treated calcium carbonate, aluminum hydroxide, aluminum oxide, titanium oxide, diatomaceous earth, barium sulfate, calcium sulfate, zeolite, zinc oxide, silicic acid, silicates, mica, magnesium carbonate, kaolin, halloysite, pyrophyllite, clays such as sericite, and talc. These may be used alone or in combination. Among these, talc is particularly preferred from the viewpoint of dispersibility in the polymer (X). The average particle size of the inorganic filler is preferably 1 μm or more from the viewpoint of anti-blocking properties of the film, and preferably 10 μm or less from the viewpoint of dispersibility in the polymer (X). From the viewpoint of satisfying the required properties of both the anti-blocking properties of the film exhibited by the incorporation of the inorganic filler and the dispersibility of the inorganic filler in the polymer (X), it is more preferable to use an inorganic filler having an average particle size of about 1 to 7 μm.

[0085] The amount of inorganic filler to be blended is preferably 0.5 to 20 parts by mass, more preferably 0.7 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of polymer (X), from the viewpoints of preventing blocking of the molded article and dispersibility of the inorganic filler in polymer (X). When the amount of inorganic filler to be blended is 20 parts by mass or less, dispersibility in polymer (X) becomes good, and the water solubility of the obtained molded article tends to be improved.

[0086] In producing the molded article of the present invention, the raw materials for the production thereof can be prepared by blending other components such as a plasticizer, a saccharide, an inorganic filler, etc. with the polymer (X) as needed, and mixing them by a known method, such as a method of dissolving or dispersing them in a solvent in a stirring tank or a method of melt-kneading them in an extruder.

[0087] (Film) Among the shapes of the molded article of the present invention, a film is one of the particularly suitable embodiments. A molded article that is a film is preferably water-soluble. A film containing the polymer (X) of the present invention may be formed only from the polymer (X), or may contain the other components described above. A film containing the polymer (X) of the present invention may be a monolayer film or a multilayer film with other films. In the case of a monolayer film, the thickness of a film containing the polymer (X) of the present invention is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 30 to 120 μm. When the film thickness is equal to or greater than the above lower limit, the film has excellent handleability, and when it is equal to or less than the above upper limit, the film has excellent water solubility.

[0088] The method for producing a film containing the polymer (X) of the present invention is not particularly limited, and it can be produced by known methods such as casting and melt extrusion. For example, the polymer (X) and, if desired, the other components described above are dissolved in an aqueous solvent, the resulting solution is placed on a smooth casting surface, and after the aqueous solvent has evaporated, the solution is peeled off from the casting surface to obtain the water-soluble film of the present invention. Water is preferred as the aqueous solvent. The casting surface may be any smooth, hard material, such as steel, aluminum, glass, or a polymer (e.g., polyolefin, polyethylene, polyamide, polyvinyl chloride, polycarbonate, polyhalocarbon, etc.). The evaporation rate of the aqueous solvent can be increased by heating the casting surface or by exposing the deposited solution to, for example, heated air or infrared radiation. The casting surface may be flat or may be a standard (drum-type) industrial film production casting machine.

[0089] In order to improve the anti-blocking properties of the film, the film surface may be roll-matted, or an anti-blocking powder such as silica or starch may be applied to the film, or an embossing treatment may be performed, as necessary. The roll-matting of the film surface can be performed by forming fine irregularities on the roll with which the film comes into contact before drying during film formation. Embossing is generally performed after the film is formed by nipping the film between an embossing roll and a rubber roll while applying heat or pressure. Although powder application has a significant anti-blocking effect, it may not be usable depending on the application of the film. Therefore, roll-matting or embossing is preferred, and roll-matting is particularly preferred in terms of the magnitude of the anti-blocking effect.

[0090] Films containing the polymer (X) of the present invention have excellent water solubility and biodegradability, and are therefore useful in a wide range of fields, such as sanitary materials, pharmaceutical packaging films, base films for hydraulic transfer printing, substrate films for embroidery, release films for molding artificial marble, seed packaging films, films for waste collection bags, etc. When used as pharmaceutical packaging films, the types of pharmaceuticals to be used are as described below in the description of the pharmaceuticals to be used in the package of the present invention.

[0091] [Package] The package of the present invention is a package comprising a chemical housed in a molded article that is the film of the present invention. Suitable embodiments of the film containing the polymer (X) of the present invention, which is one embodiment of the molded article of the present invention, are as described above. Examples of chemicals housed in the package of the present invention include pesticides, detergents (including bleaches), disinfectants, etc. Among these, the chemical is preferably a pesticide or a detergent. There are no particular restrictions on the physical properties of the chemical, and it may be acidic, neutral, or alkaline. The chemical may also contain a boron-containing compound. The chemical may be in the form of a powder, a lump, a gel, or a liquid.

[0092] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0093] [Production of Polymer and Production of Polymer Film] Polymers and polymer films were produced according to the following procedure. In the following description, the polymer produced in the comparative example, which is the comparison target for the polymer (X) produced in the example, is referred to as "polymer (Y)".

[0094] Examples 1 to 3 <Production of Polymer (X) and Production of Film of Polymer (X)> (Polymerization Step) A reactor equipped with a reflux condenser, a stirrer, a thermometer, a nitrogen inlet tube, a post-addition liquid feed section, and a pump was charged with the monomer (1), monomer (2), and methanol shown in Table 1 in the composition shown in Table 1 to prepare a mixed solution. The atmosphere in the system was purged with nitrogen while stirring the mixed solution. Separately, a methanol solution of monomer (1) (concentration: 40% by mass) was prepared as a sequential addition solution, and nitrogen was bubbled through it for 30 minutes. The temperature of the reactor was increased, and when it reached 60°C, the amount of polymerization initiator (2,2'-azobisisobutyronitrile (AIBN)) shown in Table 1 was added to initiate polymerization. During the polymerization reaction, the prepared methanol solution of monomer (1) was added dropwise to the system to maintain a constant monomer composition (molar ratio of monomer (1) to monomer (2)) in the polymerization solution. The polymerization was terminated when the polymerization rate of the monomer (2) reached 30%.

[0095] (Saponification Step) Next, unreacted monomer was removed under reduced pressure while occasionally adding methanol to prepare a methanol solution of the copolymer before saponification. Further methanol was added to the methanol solution of the copolymer before saponification to adjust the concentration of the methanol solution of the copolymer before saponification to the concentration shown in "Polymer Methanol Solution Concentration" in Table 1. Next, while maintaining the temperature at 40°C, a methanol solution of sodium hydroxide was added so that the molar ratio of sodium hydroxide to the structural units derived from monomer (2) in the copolymer before saponification was the value of "Molar Ratio [NaOH / Monomer (2)]" in Table 1, thereby carrying out saponification. After the addition of the methanol solution of sodium hydroxide, a polymer gel was formed, which was crushed in a crusher and left in air at 40°C for 1 hour to carry out the saponification reaction. 1,000 parts by mass of methanol was added to the white solid product obtained by filtration, and the mixture was left to wash at room temperature (23°C) for 3 hours. The above washing procedure was repeated twice, and the product obtained by centrifugal dewatering was then dried in a dryer at 40° C. under a reduced pressure of 1.3 Pa for 20 hours to obtain a saponified copolymer.

[0096] (Post-treatment step) Next, a reactor equipped with a reflux condenser, a stirrer, and a thermometer was charged with 100 parts by mass of the saponified copolymer obtained above and 2,400 parts by mass of water, and the temperature of the reactor was started to be increased, followed by stirring for 1 hour at 95° C. to obtain an aqueous solution of the saponified copolymer. Next, an aqueous sodium hydroxide solution was added so that the molar ratio of sodium hydroxide to the structural unit (C) in the saponified copolymer was 1, and the temperature was maintained at 40° C. and stirring was carried out for 1 hour to obtain an aqueous solution of polymer (X).

[0097] (Film Forming Step) The aqueous solution of polymer (X) obtained in the post-treatment step was cast onto a PET film and air-dried at 25° C. and 65% RH for 5 days to obtain a film of polymer (X) (thickness: 50 μm).

[0098] Example 4 The polymerization step and the saponification step were carried out in the same manner as in Example 1, except that the synthesis conditions and the saponification conditions were changed to those shown in Table 1. The post-treatment step in Example 1 was not carried out, and the polymer obtained in the saponification step was designated as polymer (X). Using the obtained polymer (X), a film of polymer (X) (thickness: 50 μm) was obtained in the same manner as in the film formation step of Example 1.

[0099] Example 5 Polymer (X) was obtained in the same manner as in Example 4, except that a post-treatment step was carried out under the same conditions as in Example 1 after the saponification step. Using the obtained polymer (X), a film of polymer (X) (thickness: 50 μm) was obtained in the same manner as in the film formation step of Example 1.

[0100] Example 6 The polymerization step and the saponification step were carried out in the same manner as in Example 1, except that the synthesis conditions and the saponification conditions were changed to those shown in Table 1. The post-treatment step in Example 1 was not carried out, and the polymer obtained in the saponification step was designated as polymer (X). The obtained polymer (X) was used to obtain a film of polymer (X) (thickness: 50 μm).

[0101] <Production of Polymer (Y) and Production of Film of Polymer (Y)> Comparative Example 1 (Polymerization Step) Monomer (2) and methanol were charged into a reactor equipped with a reflux condenser, a stirrer, a thermometer, a nitrogen inlet pipe, and a pump in a composition shown in Table 1 to prepare a mixed solution. The atmosphere in the system was replaced with nitrogen while stirring the mixed solution. The temperature of the reactor was started to be increased, and when it reached 60°C, the amount of polymerization initiator (2,2'-azobisisobutyronitrile (AIBN)) shown in Table 1 was added to initiate polymerization. The polymerization was terminated when the conversion of monomer (2) reached 30%.

[0102] (Saponification step) Next, unreacted monomer (2) was removed under reduced pressure to prepare a methanol solution of the polymer before saponification. Thereafter, the saponification step was carried out in the same manner as in Example 1. The polymer obtained in the saponification step without carrying out the post-treatment step in Example 1 was designated polymer (Y).

[0103] (Film Formation Step) A reactor equipped with a reflux condenser, a stirrer, and a thermometer was charged with 100 parts by mass of polymer (Y) obtained in the saponification step and 2,400 parts by mass of water, and the temperature of the reactor was started to be increased, followed by stirring for 1 hour at 95° C. An aqueous solution of polymer (Y) was obtained. The obtained aqueous solution of polymer (Y) was cast onto a PET film and air-dried at 25° C. and 65% RH for 5 days to obtain a film of polymer (Y) (thickness: 50 μm).

[0104] Comparative Example 2 An aqueous solution of polymer (Y) was obtained by carrying out the polymerization step, saponification step, and post-treatment step in the same manner as in Example 1, except that the synthesis conditions and saponification conditions were changed to those shown in Table 1. Using the obtained aqueous solution of polymer (Y), a film of polymer (Y) (thickness: 50 μm) was obtained in the same manner as in the film formation step of Example 1.

[0105] Comparative Examples 3 and 4 The polymerization step and the saponification step were carried out in the same manner as in Example 1, except that the synthesis conditions and the saponification conditions were changed to those shown in Table 1. The post-treatment step in Example 1 was not carried out, and the polymer obtained in the saponification step was designated as polymer (Y). Using the obtained polymer (Y), a film of polymer (Y) (thickness: 50 μm) was obtained in the same manner as in the film formation step of Comparative Example 1.

[0106] <Content and Molar Ratio of Each Structural Unit> The content (mol %) of each structural unit in the polymer (X) obtained in the examples and the polymer (Y) obtained in the comparative examples is １ Specifically, the polymers (X) obtained in Examples 1 to 3 were analyzed by H-NMR (500 MHz). １ H-NMR measurement results and the results of the polymer (X) not treated with acid １ The content (mol %) of each structural unit was determined from the results of H-NMR measurement.

[0107] (Acid-treated polymer (X) １ H-NMR Measurement) The acid treatment of polymer (X) was carried out as follows: Polymer (X) was stirred in a hydrochloric acid aqueous solution of pH 2 at 100°C for 1 hour, and then dried at 120°C to obtain all -C(=O)-OCH in the structural units derived from monomer (1) in polymer (X).３ or —C(═O)—ONa was converted to a carboxylic acid structure (—COOH) or a lactone ring structure. Note that a structural unit derived from methyl 2-(hydroxymethyl)acrylate having a carboxylic acid structure (—COOH) in its side chain is referred to as a “2-(hydroxymethyl)acrylic acid unit” in the following analysis. Also, a structural unit derived from methyl 2-(hydroxymethyl)acrylate having a lactone ring structure is a structural unit represented by the following formula (3′) formed by reacting a structural unit derived from methyl 2-(hydroxymethyl)acrylate with a structural unit derived from monomer (2) adjacent to the structural unit (this structural unit will be referred to as a “lactone ring unit” hereinafter). Note that one underlined hydrogen atom in the following formula (3′) corresponds to a “methine proton in the main chain in the lactone ring unit” described below, and two methylene groups (—CH ２ The four hydrogen atoms constituting the lactone ring unit correspond to the "methylene protons of the main chain in the lactone ring unit." The acid-treated polymer (X) was washed with methanol to remove salts, and then dried under reduced pressure at 90°C for 2 days. １ The measurement was performed using a nuclear magnetic resonance spectrometer "LAMBDA 500" manufactured by JEOL Ltd., and DMSO-d6 was used as the solvent at 80°C. １ The content of the structural units derived from the monomer (a) relative to the total monomer units of the polymer (X) (Z ａ ) (mol %), the content of structural units derived from the monomer (b) (Z ｂ ) (mol %) was calculated by the following formula: ａ )(mol%)=((X+Y) / ((W-T×3) / 2))×100 (Z ｂ ) (mol%) = 100 - (Z ａ The meanings of the symbols in the formula are as follows. In the chemical formulas described in parentheses in the following explanation, the protons from which the peaks for which the integrated values ​​were calculated are underlined. Y: Side chain proton (-CH ２ C(CH ２X: Integrated value of the peak derived from the vinyl alcohol unit, vinyl acetate unit, and 2-(hydroxymethyl)acrylic acid unit (a broad peak detected in the range of 11.0 ppm to 13.0 ppm); W: Integrated value of the methylene protons of the main chain in the vinyl alcohol unit, vinyl acetate unit, and 2-(hydroxymethyl)acrylic acid unit, the methylene protons of the main chain in the lactone ring unit, and the side chain protons (-CH ２ CH (OCOCH ３ )-) (peaks from 1.2 ppm to 2.4 ppm) T: methine proton (-CH) of the main chain in the vinyl acetate unit ２ CH (OCOCH ３ )-)) Peak integration value (peaks from 4.8 ppm to 5.2 ppm)

[0108] (Polymer (X) not treated with acid) １ H-NMR measurement) of polymer (X) not subjected to acid treatment １ The H-NMR measurement was carried out using heavy water as a solvent and the same nuclear magnetic resonance apparatus as above at 50°C. The content (Z Ａ ) (mol %), the content of the structural unit (B) (Z Ｂ ) (mol %), the content of the structural unit (C) (Z Ｃ ) (mol %), R in the above general formula (2) ３ The content of the structural unit (B) in which Z is a hydroxyl group ＢＨ ) (mol %) was calculated by the following formula: Ｃ ) (mol%) = (Q / ((P - 3 × R) / 2)) × 100 (Z Ａ ) (mol%) = (Z ａ )-(Z Ｃ ) (Z Ｂ ) (mol%) = (Z ｂ )-(Z Ｃ ) (Z ＢＨ ) (mol%) = (Z Ｂ) - ((R / ((P-3 x R) / 2)) x 100) The meanings of the symbols in the formula are as follows: P: methylene protons of the main chain in the vinyl alcohol unit, vinyl acetate unit and 2-(hydroxymethyl)acrylic acid unit, methylene protons of the main chain in the lactone ring unit, and side chain protons (-CH ２ CH (OCOCH ３ )-) derived from the total integral value (peaks from 1.5 ppm to 3.1 ppm) Q: integral value of methine protons of the main chain in the lactone ring unit (peaks from 5.0 ppm to 5.1 ppm) R: methine protons of the main chain in the vinyl acetate unit (-CH ２ CH (OCOCH ３ )-) Peak integration value (peak from 5.1 ppm to 5.7 ppm)

[0109] The content (mol %) of each structural unit in the polymer (X) obtained in Examples 4 and 5 was also measured by the same method as in Examples 1 to 3.

[0110] Polymer (X) obtained in Example 6 １ The H-NMR measurement was carried out using DMSO-d6 as a solvent and the same nuclear magnetic resonance apparatus as above at 80°C. The content (Z Ａ ) (mol %), the content of the structural unit (B) (Z Ｂ ) (mol %), the content of the structural unit (C) (Z Ｃ ) (mol %), R in the above general formula (2) ３ The content of the structural unit (B) in which Z is a hydroxyl group ＢＨ ) (mol %), the content of structural units derived from monomer (a) relative to all monomer units of polymer (X) (Z ａ ) (mol %), the content of structural units derived from the monomer (b) (Z ｂ ) (mol %) was calculated by the following formula: Ａ )(mol%)=(N') / (((P'-D')-5×(S'-G')-2×N'-3×(R'-N')) / 2+(S'-G')+N')×100 (Z ａ ) (mol%) = (Z Ａ)+(S'-G') / (((P'-D')-5×(S'-G')-2×N'-3×(R'-N')) / 2+(S'-G')+N')×100 (Z C )(mol%)=(Q') / (((P'-D')-5×(S'-G')-2×N'-3×(R'-N')) / 2+(S'-G')+N')×100 (Z Ｂ ) (mol%) = 100 - (Z ａ )-(Z Ｃ ) (Z ＢＨ ) (mol%) = (Z Ｂ )-((R'-N') / (((P'-D')-5×(S'-G')-2×N'-3×(R'-N')) / 2+(S'-G')+N'))×100 (Z ｂ ) (mol%) = 100 - (Z ａ The meanings of the symbols in the formula are as follows: P': methylene protons in the main chain in the vinyl alcohol unit, vinyl acetate unit, and units derived from methyl 2-(allyloxymethyl)acrylate, methine protons in the main chain generated by intramolecular cyclization of methyl 2-(allyloxymethyl)acrylate, methylene protons in the main chain in the lactone ring unit, and side chain protons (-CH ２ CH (OCOCH ３ )-) derived from the total integral value of the peaks (peaks at 0.7 ppm to 2.8 ppm). D': integral value of the solvent peak of DMSO (2.45 ppm to 2.55 ppm). Q': integral value of the methine protons of the main chain in the lactone ring unit (peaks at 4.5 ppm to 4.7 ppm). R': methine protons of the main chain in the vinyl acetate unit (-CH ２ CH (OCOCH ３ )-), methylene protons of the side chain allyl group in the unit derived from methyl 2-(allyloxymethyl)acrylate (—CH ２ -O-CH ２ -CH=CH ２ ) (peaks at 4.7 ppm to 5.2 ppm) N': methylene proton (-CH) of the side chain allyl group in the unit derived from methyl 2-(allyloxymethyl)acrylate ２ -O-CH ２ -CH=CH ２) (peak at 5.2 ppm to 5.3 ppm) G': integral value of the peak derived from one of the two separated protons of the main chain methine proton derived from the 1,2-glycol bond formed by the vinyl alcohol unit (peak at 3.2 ppm to 3.3 ppm) S': integral value of the peak derived from one of the two separated protons of the main chain methine proton derived from the 1,2-glycol bond formed by the vinyl alcohol unit, methylene proton (-CH) of the five-membered ring generated by intramolecular cyclization of methyl 2-(allyloxymethyl)acrylate ２ -O-CH ２ -CH-CH ２ -) Total integral value of the peak derived from one proton separated into two (peak from 3.2 ppm to 3.3 ppm)

[0111] Polymer (Y) obtained in Comparative Example 2 １ The H-NMR measurement was carried out using heavy water as a solvent and the same nuclear magnetic resonance apparatus as above at 80° C. The content (Z Ａ’ ) (mol %), the content of the structural unit (B) (Z Ｂ ) (mol %), the content of the structural unit (C′) (Z Ｃ’ ) (mol %), R in the above general formula (2) ３ The content of the structural unit (B) in which Z is a hydroxyl group ＢＨ ) (mol %) was calculated by the following formula: Ｃ’ ) (mol%) = (T / ((S - 3 × U) / 2)) × 100 (Z Ａ’ ) (mol%) = (V / ((S - 3 × U) / 2)) × 100 (Z Ｂ ) (mol%) = 100 - (Z Ａ’ )-(Z Ｃ’ ) x 2 (Z ＢＨ ) (mol%) = (Z Ｂ ) - ((U / ((S - 3 × U) / 2)) × 100) The meanings of the symbols in the formula are as follows: S: methylene protons of the main chain in the structural units derived from vinyl alcohol units, vinyl acetate units, and methyl acrylate, methylene protons of the main chain in the lactone ring unit, and side chain protons (-CH ２ CH (OCOCH３ )-) derived from the total integral value of the peaks (peaks at 1.3 ppm-2.4 ppm, peaks at 2.6-2.8 ppm) T: ((-CH ２ CH) (R ａ ) CH ２ CH (R ｂ )-)) (where R ａ -R ｂ form a bond with each other, and -R ａ -R ｂ - means -CO-O- structure) integral value (peak from 4.6 ppm to 5.0 ppm) U: methine proton (-CH ２ CH (OCOCH ３ )-) (peak between 5.0 ppm and 5.4 ppm) V: integral value of the peak derived from methine protons of the main chain in the structural unit derived from methyl acrylate (peak between 2.4 ppm and 2.6 ppm)

[0112] The content (mol %) of each structural unit in the polymer (Y) obtained in Comparative Examples 3 and 4 was also measured by a method similar to that of Comparative Example 2. The structural unit (A') and the structural unit (C') of the polymer (Y) shown in Table 3 are explained as follows.

[0113] <Structural Units (A')> Structural unit (A') of Comparative Example 2: A structural unit in which R' is a methyl group, a hydrogen atom, or sodium in the side chain (-COOR') of a structural unit derived from methyl acrylate. Structural unit (A') of Comparative Example 3: A structural unit in which R' is a methyl group, a hydrogen atom, or sodium in the side chain (-COOR') of a structural unit derived from dimethyl itaconate. Structural unit (A') of Comparative Example 4: A structural unit in which R' is a methyl group, a hydrogen atom, or sodium in the side chain (-COOR') of a structural unit derived from monomethyl maleate.

[0114] <Structural Unit (C')> Structural Unit (C') in Comparative Example 2: A structural unit represented by the following formula (3c-1)

[0115] Structural unit (C') of Comparative Example 3: Structural unit represented by the following formula (3c-2) (wherein R' is a methyl group, a hydrogen atom, or sodium.)

[0116] Structural unit (C') of Comparative Example 4: Structural unit represented by the following formula (3c-3) (wherein R' is a methyl group, a hydrogen atom, or sodium.)

[0117] the above １ From the contents of the structural units calculated by H-NMR measurement, the ratio of the molar content of the structural unit (A) to the total molar content of the structural unit (A) and the structural unit (C) [structural unit (A) / (structural unit (A)+structural unit (C))], and the ratio of the molar content of the structural unit (A') to the total molar content of the structural unit (A') and the structural unit (C') [structural unit (A') / (structural unit (A')+structural unit (C'))] were calculated.

[0118] <Method for measuring number-average degree of polymerization DPn> The number-average degree of polymerization DPn was measured by the following method. The number-average molecular weight (Mn) of polymer (X) and polymer (Y) was measured using a size-exclusion high-performance liquid chromatography device "HLC-8320GPC" manufactured by Tosoh Corporation. The measurement conditions were as follows. Column: Two HFIP-based columns "GMHHR-H(S)" manufactured by Tosoh Corporation connected in series Standard sample: Polymethyl methacrylate Solvent and mobile phase: Sodium trifluoroacetate-HFIP solution (concentration 20 mM) Flow rate: 0.2 mL / min Temperature: 40°C Sample solution concentration: 0.1% by mass (filtered through a filter with an opening diameter of 0.45 μm) Injection volume: 10 μL Detector: RI The number-average molecular weight (Mn) obtained above and the above １ Based on the composition calculated from the H-NMR measurement, the average molecular weight (MW) of all structural units contained in the polymer (X) or polymer (Y) was calculated, and the number-average degree of polymerization DPn was calculated using the following formula: DPn=Mn / MW

[0119] <Method for measuring the degree of saponification> １ Based on the composition calculated from H-NMR measurement, the degree of saponification (mol %) was calculated from the following formula: ＢＨ ) + (Z Ｃ )) × 100 / (Z ｂ )

[0120] <Method for Evaluating Water Solubility of Films> Films of polymer (X) and polymer (Y) (hereinafter simply referred to as "films") produced in the Examples and Comparative Examples were cut into 30 mm x 40 mm rectangles, which were then sandwiched between slide mounts. A 600 ml glass beaker containing 500 ml of distilled water was placed in a separate thermostatic bath adjusted to 5°C, and the distilled water in the beaker was stirred at 400 rpm using a 5 cm x 1 cm diameter rotor and a magnetic stirrer (HS-4SP, manufactured by AS ONE Corporation). After the distilled water in the beaker reached 5°C, the temperature of the distilled water was maintained at 5°C, and the slide mount described above was immersed in the stirred distilled water to begin measuring water solubility. At this time, the dissolution state of the film was visually observed, and the time until the film broke and dissolved (measured rupture time) was measured. The measured rupture time for each film was normalized to a film thickness of 50 μm according to the following formula, and the complete dissolution time for each film was calculated. Time to complete dissolution (seconds) = [50 / film thickness (μm)] ２ × Actual rupture time (seconds) The calculated complete dissolution time of the film was evaluated according to the following criteria. The evaluation was made on a four-level scale of 1 to 4, with the closer to 4 the better the result. 4: Less than 70 seconds 3: 70 seconds or more but less than 75 seconds 2: 75 seconds or more but less than 145 seconds 1: 145 seconds or more

[0121] <Method for Evaluating Biodegradability> Polymer (X) and polymer (Y) synthesized in the Examples and Comparative Examples were used as samples, and biodegradability was evaluated with reference to the biodegradability evaluation method described in OECD 301B. That is, activated sludge (obtained from a sewage treatment plant) was added to 200 ml of inorganic medium solution to a concentration of 30 ppm, and the sample polymer was added to a concentration of 15 mg DOC / L. The mixture was cultured at 22°C for 28 days using a pressure sensor-type BOD meter "Oxitop" (manufactured by WTW), and the amount of oxygen consumed by biodegradation during this culture period was measured. The biodegradation rate (%) was calculated from the obtained amount of oxygen using the following formula: Biodegradation rate (%) = (RO ２ -R2O ２ )×100 / ThOD R1O ２ : Amount of oxygen consumed in the system to which the polymer was added (mg / L) RO ２: Amount of oxygen consumed in blank (mg / L) ThOD: Theoretical oxygen demand (mg / L)

[0122] The polymer biodegradability test was judged to have been carried out normally if the decomposition rate of the control substance, sodium benzoate, exceeded 60%. The biodegradation rate of the polymer in the test that was deemed normal was evaluated according to the following criteria. The following three-level evaluation, 1 to 3, indicates that the closer to 3, the better. 3: 50% or more 2: 38% or more but less than 50% 1: Less than 38%

[0123] The synthesis conditions for polymer (X) and polymer (Y) are shown in Table 1, the evaluation results for polymer (X) are shown in Table 2, and the evaluation results for polymer (Y) are shown in Table 3.

[0124]

[0125]

[0126]

[0127] The results shown in Tables 2 and 3 show that the polymers of Examples 1 to 6, which are polymers (X) of the present invention, are excellent in water solubility and biodegradability.

Claims

1. A polymer (X) comprising a structural unit (A) represented by the following general formula (1) and a structural unit (B) represented by the following general formula (2): (In formula (1), R １ represents a hydrogen atom, an amino group, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms. ２ represents a hydrogen atom, a metal atom, an ammonium group, a phosphonium group, or a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. ３ represents a hydroxyl group or —O—C(═O)—R ４ R represents a group represented by the formula: ４ represents a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms.

2. R in the general formula (2) ３ is a hydroxyl group or —O—C(═O)—CH ３ The polymer (X) according to claim 1, 3. R ​​in the general formula (1) １ The polymer (X) according to claim 1 or 2, wherein is a hydrogen atom or an allyl group.

4. R in the general formula (1) ２ The polymer (X) according to claim 1 or 2, wherein is a hydrogen atom, an alkali metal atom, or a methyl group.

5. Polymer (X) according to claim 1 or 2, further comprising, optionally, a structural unit (C) represented by the following general formula (3), wherein the total content of the structural unit (A) and the optionally contained structural unit (C) is 0.01 to 20.0 mol % of all monomer units (100 mol %) of polymer (X): (R in the formula １ represents R in the general formula (1). １ is the same as 6. The polymer (X) according to claim 1 or 2, having a degree of saponification of 70.00 to 99.99 mol %.

7. The polymer (X) according to claim 1 or 2, having a number average degree of polymerization DPn of 100 to 5,000.

8. Polymer (X) according to claim 1 or 2, further comprising a structural unit (C) represented by the following general formula (3), wherein the ratio of the molar content of the structural unit (A) to the molar total content of the structural unit (A) and the structural unit (C) [(structural unit (A)) / (structural unit (A)+structural unit (C))] is 0.01 to 0.99: (R in the formula １ represents R in the general formula (1). １ is the same as 9. A composition comprising the polymer (X) according to claim 1 or 2.

10. An aqueous solution containing the polymer (X) according to claim 1 or 2.

11. A molded article comprising the polymer (X) according to claim 1 or 2.

12. The molded article according to claim 11, which is a film.

13. The molded article according to claim 12, which is water-soluble.

14. A package containing a medicine in the molded article according to claim 12.

15. The package of claim 14, wherein the chemical is a pesticide or a detergent.

16. A method for producing polymer (X) according to claim 1 or 2, comprising the steps of copolymerizing a monomer (a) represented by the following general formula (I) with a monomer (b) represented by the following general formula (II) to obtain a copolymer, and saponifying the copolymer: (R in formula (I) １ and R ２ is R in the general formula (1). １ and R ２ and R in formula (II) is the same as ４ is R in the description of the general formula (2) ４ is the same as 17. A polymer (X') containing a structural unit (C) represented by the following general formula (3): (In formula (3), R １ represents a hydrogen atom, an amino group, a substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocyclic group having 3 to 20 carbon atoms.