Method for manufacturing polyaspartic acid derivative

Abstract

To provide a method for manufacturing a polyaspartic acid derivative, capable of suppressing decomposition even when performing modification reaction by amine, such as n-dodecyl amine at high temperature and obtaining a polyaspartic acid derivative excellent in storage stability.SOLUTION: A method for manufacturing a polyaspartic acid derivative comprises the step (a) of modifying a polymer including a monomeric unit derived from succinic acid imide by specific amine under the existence of a solvent. The solvent includes a compound including one or more selected from a group consisting of dimethylformamide, dimethylsulfoxide and N-methyl pyrolidone and at least one hydroxyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing a polyaspartic acid derivative. [Background technology]

[0002] Polyacrylic acid polymers, such as carboxyvinyl polymers, have been used as thickeners for cosmetics and water-absorbent polymers for hygiene products. However, because polyacrylic acid polymers are derived from petroleum and are non-biodegradable, there is a growing demand for alternatives to polyacrylic acid polymers from an environmental perspective.

[0003] Polyaspartic acid derivatives are known as alternative polymers. Polyaspartic acid derivatives are made from polysuccinimide, which is obtained by, for example, thermal condensation of bio-derived aspartic acid. Polyaspartic acid derivatives are obtained by modifying polysuccinimide with specific amines such as n-dodecylamine or hydroxypropylamine (Patent Document 1). Polysuccinimide has poor solubility in solvents and dissolves only in high-boiling-point solvents such as dimethylformamide. Therefore, in the production of the polyaspartic acid derivatives in Patent Document 1, polysuccinimide is dissolved in dimethylformamide and then subjected to a modification reaction with an amine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-344061 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when polysuccinimide is modified at high temperatures with an amine such as n-dodecylamine in a high-boiling solvent such as dimethylformamide, not only the modification reaction but also the decomposition reaction proceeds, resulting in the problem of a low molecular weight polyaspartic acid derivative. Furthermore, the decomposition proceeds with prolonged storage, further reducing the molecular weight of the polyaspartic acid derivative, resulting in poor storage stability. Therefore, the modification reaction had to be carried out over a long period of time at low temperatures. On the other hand, while the decomposition reaction is suppressed when the reaction is carried out at low temperatures, and a high molecular weight polyaspartic acid derivative is obtained, the storage stability of the polyaspartic acid derivative when prepared as an aqueous solution is poor. Therefore, an object of the present disclosure is to provide a method for producing a polyaspartic acid derivative, which can suppress decomposition and produce a polyaspartic acid derivative having excellent storage stability. [Means for solving the problem]

[0006] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they discovered that polyaspartic acid derivatives having high molecular weights and excellent storage stability can be obtained by using one or more solvents selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone in combination with a compound having at least one hydroxyl group in a modification reaction with an amine such as n-dodecylamine, and thus completed the invention of the present disclosure.

[0007] That is, the invention of the present disclosure is as follows. [1] A method for producing a polyaspartic acid derivative, comprising the following step (a): Step (a): A step of modifying a polymer containing a succinimide-derived monomer unit with an amine represented by the following general formula (1) in the presence of a solvent, R1-NH2(1) (In the formula, R1 represents a group containing a hydrocarbon group having 3 to 22 carbon atoms which may contain a heteroatom.) The solvent contains one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group. [2] The method according to [1], wherein step (a) is carried out at 40°C or higher. [3] The method according to [1] or [2], wherein step (a) is carried out at 150°C or lower. [4] The production method according to [1] or [2], wherein the ratio of the number of moles of hydroxyl groups of the compound having at least one hydroxyl group to the number of moles of monomer units derived from succinimide in the solvent in step (a) is 1.0 to 10.0. [Effects of the Invention]

[0008] According to the present invention, it is possible to obtain a polyaspartic acid derivative having a high molecular weight and high viscosity, and further, according to the present invention, it is possible to obtain a polyaspartic acid derivative having excellent storage stability even when stored in the form of an aqueous solution for a long period of time. In particular, when the modification reaction with an amine such as n-dodecylamine is carried out at a high temperature, the reaction time can be shortened compared to when the reaction is carried out at a low temperature. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure will be described in more detail below. Note that the present disclosure is not limited to the following embodiments.

[0010] The expressions "XX or more and YY or less" or "XX to YY" that represent a numerical range mean a numerical range including the endpoints, that is, the lower limit and the upper limit, unless otherwise specified. When numerical ranges are stated in stages, the upper and lower limits of each numerical range can be combined in any way.

[0011] The method for producing a polyaspartic acid derivative of the present disclosure (also referred to as the "production method of the present disclosure") includes the following step (a): Step (a): A step of modifying a polymer containing a succinimide-derived monomer unit with an amine represented by the following general formula (1) in the presence of a solvent, R1-NH2(1) (In the formula, R1 represents a group containing a hydrocarbon group having 3 to 22 carbon atoms which may contain a heteroatom.) The solvent contains one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group.

[0012] [Polymer containing succinimide-derived monomer units] The "monomer unit derived from succinimide" of the "polymer containing a monomer unit derived from succinimide" (also referred to as "polymer") in step (a), step (b) described below, and step (c) described below is a monomer unit represented by the following formula (2) (also referred to as "monomer unit CU").

[0013] [ka]

[0014] An example of a polymer containing a monomer unit derived from succinimide is polysuccinimide (also referred to as "PSI"). Polysuccinimide is a polymer formed by polymerizing the monomer unit represented by the above formula (2). The degree of polymerization of the monomer unit represented by the above formula (2) in polysuccinimide is not particularly limited, but is, for example, 10 to 10,000.

[0015] Polysuccinimide can be produced by known methods, for example, by heating aspartic acid in the presence of phosphoric acid at 170 to 190°C in a vacuum to cause dehydration condensation. To obtain a polysuccinimide with a higher molecular weight, the polysuccinimide obtained as described above can be treated with a condensing agent such as dicyclohexylcarbodiimide. The molecular weight of the polysuccinimide is not particularly limited, but may be, for example, a weight-average molecular weight of 20,000 or more, 50,000 or more, or 70,000 or more, or 500,000 or less, 200,000 or less, or 100,000 or less. Specifically, the weight-average molecular weight may be, for example, 20,000 to 500,000, 50,000 to 200,000, or 70,000 to 100,000. In the present disclosure, the weight-average molecular weight refers to a converted value measured by the GPC method (differential refractometer) using polystyrene as a standard substance, and specifically refers to the weight-average molecular weight measured using a G1000HHR column (TSKgel (registered trademark), manufactured by Tosoh Corporation), a G4000HHR column (TSKgel (registered trademark), manufactured by Tosoh Corporation), or a GMHHR-H column (TSKgel (registered trademark), manufactured by Tosoh Corporation) using dimethylformamide containing 10 mM lithium bromide as an eluent.

[0016] The amount of the succinimide-derived monomer units present in the constituent monomers of a polymer containing the succinimide-derived monomer units is not particularly limited, and may be, for example, 40 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more, or 100 mol% or less, 98 mol% or less, 95 mol% or less, 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, or 50 mol% or less, or any compatible combination thereof. Specifically, it may be, for example, 40 mol% to 100 mol%, 50 mol% to 98 mol%, 60 mol% to 95 mol%, 70 mol% to 90 mol%, 80 mol% to 95 mol%, 90 mol% to 98 mol%, 95 mol% to 100 mol%, 70 mol% to 80 mol%, 60 mol% to 70 mol% or less, 50 mol% to 60 mol%, or 40 mol% to 50 mol%.

[0017] The polymer containing a monomer unit derived from succinimide may contain a monomer unit other than the monomer unit derived from succinimide. For example, A polymer containing the units may be partially modified with one or more selected from the group consisting of amine A and amine B. Amine A and amine B will be described later. In other words, a polymer containing a monomer unit derived from succinimide may further contain one or more selected from the group consisting of α- or β-polyaspartic acid monomer units AU (also referred to as "monomer units AU") represented by the following general formula (3), α- or β-polyaspartic acid monomer units B'-U represented by the following general formula (4), and α- or β-polyaspartic acid monomer units B"-U represented by the following general formula (5). Note that one or more selected from the group consisting of α- or β-polyaspartic acid monomer units B'-U represented by the general formula (4) and α- or β-polyaspartic acid monomer units B"-U represented by the general formula (5) are also collectively referred to as "monomer units BU".

[0018] [ka] (In the formula, R1 represents a group containing a hydrocarbon group having 3 to 22 carbon atoms which may contain a heteroatom.)

[0019] Regarding R1 in general formula (3), the explanation given below regarding R1 in general formula (1) is incorporated herein by reference.

[0020] [ka] (In the formula, R2 represents a group containing a hydrocarbon group having 1 to 16 carbon atoms which may contain a heteroatom.)

[0021] [ka] (In the formula, R3 represents a group containing a hydrocarbon group having 1 to 8 carbon atoms which may contain a heteroatom, and R4 represents a group containing a hydrocarbon group having 1 to 8 carbon atoms which may contain a heteroatom.)

[0022] The explanation for R2 in general formula (4) is incorporated herein by reference, and the explanation for R2 in general formula (7) is incorporated herein by reference, while the explanation for R3 and R4 in general formula (8) is incorporated herein by reference.

[0023] The monomer unit AU may be formed by modification with amine A in step (a). The monomer unit BU may be formed by modification with amine B in step (b) described below. For example, when the production method of the present disclosure further includes step (b) described below and step (b) is performed before step (a), the polymer containing succinimide-derived monomer units and subjected to step (a) may be partially modified with amine B. For example, when the production method of the present disclosure further includes step (b) described below and step (b) is performed after step (a), the polymer containing succinimide-derived monomer units and subjected to step (b) may be partially modified with amine A. For example, when the production method of the present disclosure further includes step (c) described below and step (a) is performed before step (c), the polymer containing succinimide-derived monomer units and subjected to step (c) may be partially modified with amine A. Furthermore, for example, when the production method of the present disclosure further includes step (b) and step (c), and step (b) is performed before step (c), the polymer containing a succinimide-derived monomer unit to be subjected to step (c) may be partially modified with amine B.

[0024] The polymer containing the succinimide-derived monomer unit may have a crosslinked structure. In other words, the polymer containing the succinimide-derived monomer unit may further contain an α- or β-polyaspartic acid monomer unit Crosslink-U (also referred to as "monomer unit Crosslink-U") represented by the following general formula (6):

[0025] [ka] (In the formula, the wavy lines indicate crosslinking sites.)

[0026] The crosslinked structure may be formed, for example, by step (c) described below. For example, when the production method of the present disclosure further includes step (c) described below and step (c) is performed before step (a), the polymer containing monomer units derived from succinimide and subjected to step (a) may have a crosslinked structure. Also, for example, when the production method of the present disclosure further includes steps (b) and (c) and step (c) is performed before step (b), the polymer containing monomer units derived from succinimide and subjected to step (b) may have a crosslinked structure.

[0027] The polymer containing a monomer unit derived from succinimide may be a polymer containing a monomer unit derived from succinimide and one or more selected from the group consisting of a monomer unit AU, a monomer unit B'-U, a monomer unit B"-U, and a monomer unit Crosslink-U. Furthermore, the polymer containing a monomer unit derived from succinimide may be a polymer consisting of a monomer unit derived from succinimide and one or more selected from the group consisting of a monomer unit AU, a monomer unit B'-U, a monomer unit B"-U, and a monomer unit Crosslink-U.

[0028] [Step (a)] Step (a) is a step of modifying a polymer containing a monomer unit derived from succinimide with an amine represented by the following general formula (1) (also referred to as "amine A") in the presence of a solvent. R1-NH2(1) (In the formula, R1 represents a group containing a hydrocarbon group having 3 to 22 carbon atoms which may contain a heteroatom.)

[0029] In step (a), the succinimide ring in the polymer is opened by amine A, and amine A is added to the succinimide-derived monomer unit. That is, in step (a), an addition reaction of amine A occurs, accompanied by cleavage of the succinimide ring.

[0030] In general formula (1), R1 is not particularly limited as long as it is a group containing a hydrocarbon group having 3 to 22 carbon atoms. R1 may be saturated or unsaturated, may be branched or linear, or may have a ring structure. Specific examples of hydrocarbon groups having 3 to 22 carbon atoms include linear alkyl groups such as propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl; branched alkyl groups such as isopropyl, isobutyl, isopentyl, and isohexyl; cycloalkyl groups such as cyclobutyl, cyclopentyl, and cyclohexyl; cycloalkylalkyl groups such as cyclobutylmethyl, cyclopentylmethyl, cyclohexylmethyl, cyclobutylethyl, cyclopentylethyl, cyclohexylethyl, cyclobutylpropyl, cyclopentylpropyl, cyclohexylpropyl, cyclobutylbutyl, cyclopentylbutyl, and cyclohexylbutyl; and alkenyl groups such as propenyl, butenyl, pentenyl, and hexenyl. Among these, alkyl groups are preferred as hydrocarbon groups having 3 to 22 carbon atoms.

[0031] The number of carbon atoms in the hydrocarbon group having 3 to 22 carbon atoms in R1 is not particularly limited, and may be, for example, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or 11 or more, or may be 22 or less, 21 or less, 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, or 14 or less. The number of carbon atoms in the hydrocarbon group having 3 to 22 carbon atoms in R1 may specifically be, for example, 3 to 22, 4 to 21, 5 to 20, 6 to 19, 7 to 18, 8 to 17, 9 to 16, 10 to 15, or 11 to 14.

[0032] Furthermore, the group containing a hydrocarbon group having 3 to 22 carbon atoms in R1 may contain a heteroatom. Examples of the heteroatom include one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of the group containing a hydrocarbon group having 3 to 22 carbon atoms and containing a heteroatom include the above-mentioned hydrocarbon group having 3 to 22 carbon atoms interposed by a heteroatom. Examples of the interposed heteroatom include one or more selected from the group consisting of -O-, -N-, and -S-.

[0033] Therefore, the amine A may be, for example, an amine represented by the following general formula (1′): R 11 -LR 12 -NH2(1') (In the formula, R 11 and R 12 each represents a hydrocarbon group having 1 to 21 carbon atoms, and R 11 The number of carbon atoms in R 12 The sum of the number of carbon atoms in R is 3 to 22. 11 The number of carbon atoms in R is preferably 18 to 21. 12 The number of carbon atoms is preferably 1 to 4. L represents a nitrogen atom, an oxygen atom, or a sulfur atom.

[0034] R 11 and R 12 may be saturated or unsaturated, may be branched or straight, and may have a ring structure.

[0035] "R" in general formula (1') 11 -LR 12 Specific examples of "-" include ethoxymethylene, propoxymethylene, butoxymethylene, pentoxymethylene, hexanoxymethylene, heptanoxymethylene, octanoxymethylene, nonanoxymethylene, decanoxymethylene, undecanoxymethylene, dodecanoxymethylene, tridecanoxymethylene, tetradecanoxymethylene, pentadecanoxymethylene, hexadecanoxymethylene, heptadecanoxymethylene, octadecanoxymethylene, nonadecanoxymethylene, ethoxyethylene, propoxyethylene, butoxyethylene, pentoxyethylene, and hexanoxyethylene groups. , heptanoxyethylene group, octanoxyethylene group, nonanoxyethylene group, decanoxyethylene group, undecanoxyethylene group, dodecanoxyethylene group, tridecanoxyethylene group, tetradecanoxyethylene group, pentadecanoxyethylene group, hexadecanoxyethylene group, heptadecanoxyethylene group, octadecanoxyethylene group, nonadecanoxyethylene group, ethoxypropylene group, propoxypropylene group, butoxypropylene group, pentoxypropylene group, hexanoxypropylene group, heptanoxypropylene group, octanoxypropylene group, nonanoxypropylene group, decanoxypropylene group, undecanoxypropylene group, Dodecanoxypropylene group, tridecanoxypropylene group, tetradecanoxypropylene group, pentadecanoxypropylene group, hexadecanoxypropylene group, heptadecanoxypropylene group, octadecanoxypropylene group, nonadecanoxypropylene group, ethoxytetramethylene group, propoxytetramethylene group, butoxytetramethylene group, pentoxytetramethylene group, hexanoxytetramethylene group, heptanoxytetramethylene group alkyl alkylene groups such as a lamethylene group, an octanoxytetramethylene group, a nonanoxytetramethylene group, a decanoxytetramethylene group, an undecanoxytetramethylene group, a dodecanoxytetramethylene group, a tridecanooxytetramethylene group, a tetradecanoxytetramethylene group, a pentadecanooxytetramethylene group, a hexadecanoxytetramethylene group, a heptadecanooxytetramethylene group, and an octadecanooxytetramethylene group; Ethylthiomethyl group, propylthiomethyl group, butylthiomethyl group, pentylthiomethyl group, hexylthiomethyl group, heptylthiomethyl group, octylthiomethyl group, nonylthiomethyl group, decylthiomethyl group, undecylthiomethyl group, dodecylthiomethyl group, tridecylthiomethyl group, tetradecylthiomethyl group, pentadecylthiomethyl group, hexadecylthiomethyl group, heptadecylthiomethyl group, octadecylthiomethyl group, nonadecylthiomethyl group, ethylthiomethyl group thioethyl, propylthioethyl, butylthioethyl, pentylthioethyl, hexylthioethyl, heptylthioethyl, octylthioethyl, nonylthioethyl, decylthioethyl, undecylthioethyl, dodecylthioethyl, tridecylthioethyl, tetradecylthioethyl, pentadecylthioethyl, hexadecylthioethyl, heptadecylthioethyl, octadecylthioethyl, nonadecylthioethyl, ethylthiopropyl, pro and alkylthioalkyl groups such as ethylthiopropyl group, butylthiopropyl group, pentylthiopropyl group, hexylthiopropyl group, heptylthiopropyl group, octylthiopropyl group, nonylthiopropyl group, decylthiopropyl group, undecylthiopropyl group, dodecylthiopropyl group, tridecylthiopropyl group, tetradecylthiopropyl group, pentadecylthiopropyl group, hexadecylthiopropyl group, heptadecylthiopropyl group, octadecylthiopropyl group, nonadecylthiopropyl group, ethylthiobutyl group, propylthiobutyl group, butylthiobutyl group, pentylthiobutyl group, hexylthiobutyl group, heptylthiobutyl group, octylthiobutyl group, nonylthiobutyl group, decylthiobutyl group, undecylthiobutyl group, dodecylthiobutyl group, tridecylthiobutyl group, tetradecylthiobutyl group, pentadecylthiobutyl group, hexadecylthiobutyl group, heptadecylthiobutyl group, and octadecylthiobutyl group.

[0036] The amine A may be used alone or in combination of two or more.

[0037] The amount of amine A charged is not particularly limited, and may be, for example, 20 mol% or more, 25 mol% or more, or 30 mol% or more, or 60 mol% or less, 58 mol% or less, or 57 mol% or less, relative to the number of moles of the succinimide-derived monomer units. Specifically, the amount of amine A charged may be, for example, 20 mol% to 60 mol%, 25 mol% to 58 mol%, or 30 mol% to 57 mol%. Furthermore, when step (a) is performed after step (b), the amount of amine A charged is preferably greater than the amount required for the reaction in order to promote the reaction of step (a). In the present disclosure, the "number of moles of succinimide-derived monomer units" can be calculated, for example, by dividing the weight of the charged amount of polysuccinimide by the molecular weight of the succinimide-derived monomer units.

[0038] The solvent (reaction solvent) in step (a) contains one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group.

[0039] Generally, amine A and succinimide are reacted in a high boiling point solvent such as dimethylformamide. When reacted with a polymer containing a monomer unit derived from amine A at high temperatures, not only the modification reaction by amine A but also the decomposition reaction proceeds, resulting in a problem of a low molecular weight polyaspartic acid derivative. Also, when reacted at low temperatures, a high molecular weight polyaspartic acid derivative is obtained, but this has the problem of poor storage stability when stored in aqueous solution for a long period of time. On the other hand, according to the production method of the present disclosure, by using one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone in combination with a compound having at least one hydroxyl group in step (a), decomposition can be suppressed, resulting in a polyaspartic acid derivative with a high molecular weight and excellent storage stability. This is presumably because, while it is generally believed that hydrolysis occurs due to trace amounts of water present in the reaction system when a modification reaction with amine A is carried out at high temperatures, the use of a compound having at least one hydroxyl group in combination with amine A hydrogen bonds with the water in the reaction system, thereby suppressing hydrolysis and maintaining a high molecular weight. Furthermore, it is presumed that amine A hydrogen bonds with the compound having at least one hydroxyl group, thereby imparting a certain regular, more stable structure to the polyaspartic acid derivative in the reaction with a polymer containing a succinimide-derived monomer unit, thereby resulting in excellent storage stability.

[0040] One or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone act as a solvent for dissolving a polymer containing a succinimide-derived monomer unit. Dimethyl sulfoxide and N-methylpyrrolidone are particularly preferred due to their low toxicity. Therefore, the one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone are preferably one or more selected from the group consisting of dimethyl sulfoxide and N-methylpyrrolidone. One or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone may be used alone or in combination of two or more.

[0041] The compound having at least one hydroxyl group is not particularly limited, but examples thereof include lower alcohols having 1 to 5 carbon atoms, such as methanol, ethanol, n-propanol, and isopropanol; polyhydric alcohols having 1 to 8 carbon atoms, such as dihydric alcohols, such as butylene glycol, propylene glycol, ethylene glycol, and dibutylene glycol, and trihydric alcohols, such as glycerin; sterols, such as cholesterol, sitosterol, phytosterol, and lanosterol; monosaccharides, such as pentoses, such as ribose, arabinose, and xylose, and hexoses, such as glucose, galactose, and fructose; and sugar alcohols, such as sorbitol, xylitol, and maltitol. Among these, the compound having at least one hydroxyl group preferably includes one or more selected from the group consisting of methanol, ethanol, 2-propanol, and isopropanol, since this will reduce the viscosity of the reaction liquid. The compound having at least one hydroxyl group may be used alone or in combination of two or more.

[0042] The solvent in step (a) may contain one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group, as long as the reaction in step (a) can proceed. Specifically, the solvent may contain, for example, an aprotic polar organic solvent such as dimethylacetamide (DMAc), dimethylimidazolidinone (DMI), sulfolane, 3-methoxy-N,N-dimethylpropanamide, or 3-butoxy-N,N-dimethylpropanamide.

[0043] The total content of one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the compound having at least one hydroxyl group in the solvent in step (a) is not particularly limited as long as the reaction in step (a) can proceed, and may be, for example, The total content may be, for example, 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more, or 100% by weight or less, 95% by weight or less, 90% by weight or less, or 80% by weight or less, or any compatible combination thereof. The total content may be, for example, 70% by weight to 100% by weight, 80% by weight to 95% by weight, 90% by weight to 95% by weight, 95% by weight to 100% by weight, 80% by weight to 90% by weight, or 70% by weight to 80% by weight.

[0044] The ratio of the number of moles of hydroxyl groups in the compound having at least one hydroxyl group to the number of moles of monomer units derived from succinimide in the solvent in step (a) ((number of moles of hydroxyl groups in the compound having at least one hydroxyl group) / (number of moles of monomer units derived from succinimide)) is not particularly limited, but is preferably 1.0 or more, more preferably 2.0 or more, even more preferably 3.0 or more, and still more preferably 4.0 or more. On the other hand, it is preferably 10.0 or less, more preferably 8.0 or less, even more preferably 6.0 or less, and still more preferably 5.0 or less. The ratio is, for example, 1.0 to 10.0, 2.0 to 8.0, 3.0 to 6.0, or 4.0 to 5.0. In the present disclosure, the "number of moles of monomer units derived from succinimide" can be calculated, for example, by dividing the weight of the charged amount of polysuccinimide by the molecular weight of the monomer units derived from succinimide.

[0045] The weight ratio of the content of one or more compounds selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone to the content of the compound having at least one hydroxyl group in the solvent in step (a) is not particularly limited, and may be, for example, 0.5 or more, 1.0 or more, 2.0 or more, 3.0 or more, or 4.0 or more, or 20.0 or less, 15.0 or less, 10.0 or less, 5.0 or less, 4.0 or less, or 3.0 or less, or any compatible combination thereof. The weight ratio may be, for example, 0.5 to 20.0, 1.0 to 15.0, 2.0 to 10.0, 3.0 to 5.0, 4.0 to 10.0, 0.5 to 4.0, or 1.0 to 3.0.

[0046] The concentration of the polymer containing a monomer unit derived from succinimide in the solvent in step (a) is not particularly limited, and may be, for example, 1.0 wt % or more, 3.0 wt % or more, 5.0 wt % or more, 10.0 wt % or more, 15.0 wt % or more, or 20.0 wt % or more, or 50.0 wt % or less, 40.0 wt % or less, 30.0 wt % or less, 20.0 wt % or less, 15.0 wt % or less, or 10.0 wt % or less, or any compatible combination thereof. The concentration of the polymer containing a monomer unit derived from succinimide in the solvent in step (a) may be, for example, 1.0 wt % to 50.0 wt %, 3.0 wt % to 40.0 wt %, 5.0 wt % to 30.0 wt %, 10.0 wt % to 20.0 wt %, 15.0 wt % to 50.0 wt %, 20.0 wt % to 40.0 wt %, 1.0 wt % to 15.0 wt %, or 3.0 wt % to 10.0 wt %.

[0047] A specific procedure for step (a) may include, for example, dissolving a polymer containing succinimide-derived monomer units in a solvent, adding dropwise a solvent solution containing amine A dissolved therein, and reacting the resulting mixture under predetermined temperature conditions. In this case, the solvent for dissolving the polymer containing succinimide-derived monomer units and the solvent for dissolving amine A are preferably solvents containing one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group, respectively.

[0048] The temperature conditions for step (a) are not particularly limited as long as the progress of the reaction can be substantially maintained. Step (a) may be carried out at a temperature of, for example, 5° C. or higher, 10° C. or higher, 15° C. or higher, 20° C. or higher, 25° C. or higher, 30° C. or higher, or 35° C. or higher, or at a temperature of 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, 110° C. or lower, 100° C. or lower, 95° C. or lower, 90° C. or lower, 85° C. or lower, 80° C. or lower, 75° C. or lower, 70° C. or lower, 65° C. or lower, or 60° C. or lower. Step (a) may be carried out at a temperature of, for example, 5°C to 150°C, 10°C to 140°C, 15°C to 130°C, 20°C to 120°C, 25°C to 110°C, 30°C to 100°C, 35°C to 95°C, 5°C to 90°C, 10°C to 85°C, 15°C to 80°C, 20°C to 75°C, 25°C to 70°C or less, 30°C to 65°C, or 35°C to 60°C. In particular, according to the production method of the present disclosure, the molecular weight of the polyaspartic acid derivative can be maintained high even when step (a) is carried out at a high temperature. Therefore, step (a) may be carried out at a temperature of, for example, 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, 60°C or higher, 65°C or higher, 70°C or higher, 75°C or higher, or 80°C or higher, or at a temperature of 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, 95°C or lower, 90°C or lower, 85°C or lower, 80°C or lower, 75°C or lower, 70°C or lower, 65°C or lower, or 60°C or lower, or at a compatible combination thereof. Step (a) may be carried out at a temperature of, for example, 40°C to 150°C, 45°C to 140°C, 50°C to 130°C, 55°C to 120°C, 60°C to 110°C, 65°C to 100°C, 70°C to 95°C, 75°C to 90°C, 80°C to 85°C, 40°C to 80°C, 45°C to 75°C, 50°C to 70°C, 55°C to 65°C, or 55°C to 60°C.

[0049] The reaction time for step (a) is not particularly limited as long as the reaction in step (a) can proceed, but may be, for example, 5 minutes or more, 10 minutes or more, 20 minutes or more, 30 minutes or more, 40 minutes or more, 50 minutes or more, 1 hour or more, 2 hours or more, or 3 hours or more, or 10 hours or less, 5 hours or less, 4 hours or less, 3 hours or less, 2 hours or less, 1 hour or less, 50 minutes or less, 40 minutes or less, 30 minutes or less, 20 minutes or less, or 10 minutes or less, or any compatible combination thereof. Specifically, the reaction time may be, for example, 5 minutes to 10 hours, 10 minutes to 5 hours, 20 minutes to 4 hours, 30 minutes to 3 hours, 40 minutes to 2 hours, 50 minutes to 1 hour, 1 hour to 10 hours, 2 hours to 5 hours, 3 hours to 4 hours, 5 minutes to 50 minutes, 10 minutes to 40 minutes, 20 minutes to 30 minutes or less, 5 minutes to 20 minutes, or 5 minutes to 10 minutes.

[0050] The polyaspartic acid derivative obtained in step (a) may be a polymer containing succinimide-derived monomer units in which all of the succinimide-derived monomer units have been modified with amine A, or a polymer in which some of the succinimide-derived monomer units are unmodified.

[0051] [Step (b)] The manufacturing method of the present disclosure may further include the following step (b): Step (b): A step of modifying a polymer containing a monomer unit derived from succinimide with one or more amines selected from the group consisting of amines represented by the following general formula (7) and amines represented by the following general formula (8): OH-R2-NH2(7) (In the formula, R2 represents a group containing a hydrocarbon group having 1 to 16 carbon atoms which may contain a heteroatom.) OH-R3-NH-R4(8) (In the formula, R3 represents a group containing a hydrocarbon group having 1 to 8 carbon atoms which may contain a heteroatom, and R4 represents a group containing a hydrocarbon group having 1 to 8 carbon atoms which may contain a heteroatom.)

[0052] In step (b), the succinimide ring in the polymer is opened by one or more amines selected from the group consisting of amines represented by general formula (7) and amines represented by general formula (8) (these are also collectively referred to as "amine B"), whereby amine B is added to the succinimide-derived monomer unit. That is, in step (b), amine B is added to the succinimide-derived monomer unit, which is accompanied by the cleavage of the succinimide ring. The following addition reaction occurs:

[0053] In general formula (7), R2 is not particularly limited as long as it is a group containing a hydrocarbon group having 1 to 16 carbon atoms, and may contain a heteroatom. R2 may be saturated or unsaturated, branched or linear, or may have a ring structure. Specific examples of the hydrocarbon group having 1 to 16 carbon atoms include an ethylene group (-CH2CH2-), a trimethylene group (-CH2CH2CH2-), a tetramethylene group (-CH2CH2CH2CH2-), a pentamethylene group (-CH2CH2CH2CH2CH2-), a hexamethylene group (-CH2CH2CH2CH2CH2CH2-), a heptamethylene group (-CH2CH2CH2CH2CH2CH2-), and the like. Examples of alkylene groups include linear alkylene groups such as an octamethylene group (-CH(CH)CH-, -CHCH(CH)-) and an octamethylene group (-CHCHCHCHCHCHCHCHCH-); branched alkylene groups such as a propylene group (-CH(CH)CH-, -CHCH(CH)-) and a 1,2-dimethylethylene group (-(CH)CHCH(CH)-); and alkenyl groups such as a propenylene group (-CHCH=CH-, -CH=CHCH-). Among these, branched or straight chain alkylene groups are preferred, and straight chain alkylene groups are more preferred.

[0054] Furthermore, the group containing a hydrocarbon group having 1 to 16 carbon atoms in R2 may contain a heteroatom, such as one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of groups containing a hydrocarbon group having 1 to 16 carbon atoms and containing a heteroatom include those in which one or more hydrogen atoms of the above-mentioned hydrocarbon groups having 1 to 16 carbon atoms are substituted with a substituent containing a heteroatom. Examples of the substituent containing a heteroatom include one or more selected from the group consisting of a hydroxy group (-OH), an amino group (-NH), and a thiol group (-SH). Specific examples of groups containing a hydrocarbon group having 1 to 16 carbon atoms substituted with a substituent containing a heteroatom include hydroxyalkylene groups such as a hydroxyethylene group (-CH(OH)CH-), a hydroxypropylene group (-CHCH(OH)CH-), and a hydroxybutylene group (-CHCHCH(OH)CH-); and polyhydroxyalkylene groups such as a group obtained by removing the amino group (-NH-) and the terminal hydroxy group (-OH) from D-glucamine.

[0055] The number of carbon atoms in the group containing a hydrocarbon group having 1 to 16 carbon atoms in R2 is not particularly limited, and may be, for example, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, or 12 or more, or 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, or 5 or less, or any compatible combination thereof. Specific examples of the number of carbon atoms in the group containing a hydrocarbon group having 1 to 16 carbon atoms in R2 may be 1 to 16, 2 to 15, 3 to 14, 4 to 13, 5 to 12, 6 to 11, 7 to 10, 8 to 9, 9 to 16, 10 to 15, 11 to 14, 12 to 13, 1 to 8, 2 to 7, 3 to 6, or 4 to 5.

[0056] In general formula (8), R3 is not particularly limited as long as it is a group containing a hydrocarbon group having 1 to 8 carbon atoms, and may contain a heteroatom. R3 may be saturated or unsaturated, branched or linear, or may have a ring structure. Specific examples of the hydrocarbon group having 1 to 8 carbon atoms include linear alkylene groups such as an ethylene group (-CH2CH2-), a trimethylene group (-CH2CH2CH2-), a tetramethylene group (-CH2CH2CH2CH2-), a pentamethylene group (-CH2CH2CH2CH2CH2-), a hexamethylene group (-CH2CH2CH2CH2CH2CH2-), a heptamethylene group (-CH2CH2CH2CH2CH2CH2CH2-), and an octamethylene group (-CH2CH2CH2CH2CH2CH2CH2CH2-); a propylene group (-CH(CH 3) Branched alkylene groups such as CH2-, -CH2CH(CH3)-, and 1,2-dimethylethylene group (-(CH3)CHCH(CH3)-); and alkenyl groups such as propenylene group (-CH2CH=CH-, -CH=CHCH2-). Among these, branched or straight chain alkylene groups are preferred, and straight chain alkylene groups are more preferred.

[0057] Furthermore, the group containing a hydrocarbon group having 1 to 8 carbon atoms in R3 may contain a heteroatom, such as one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of groups containing a hydrocarbon group having 1 to 8 carbon atoms and containing a heteroatom include those in which one or more hydrogen atoms of the above-mentioned hydrocarbon group having 1 to 8 carbon atoms are substituted with a substituent containing a heteroatom. Examples of the substituent containing a heteroatom include one or more selected from the group consisting of a hydroxy group (-OH), an amino group (-NH), and a thiol group (-SH). Specific examples of groups containing a hydrocarbon group having 1 to 8 carbon atoms substituted with a substituent containing a heteroatom include hydroxyalkylene groups such as a hydroxyethylene group (-CH(OH)CH-), a hydroxypropylene group (-CHCH(OH)CH-), and a hydroxybutylene group (-CHCHCH(OH)CH-); and polyhydroxyalkylene groups such as a group obtained by removing the amino group (-NH-) and the terminal hydroxy group (-OH) from D-glucamine.

[0058] The number of carbon atoms in the hydrocarbon group having 1 to 8 carbon atoms in R3 is not particularly limited, and may be, for example, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, or 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, or 3 or less, or any compatible combination thereof.Specifically, the number of carbon atoms in the hydrocarbon group having 1 to 8 carbon atoms in R3 may be, for example, 1 to 8, 2 to 7, 3 to 6, 4 to 5, 6 to 8, 1 to 4, or 2 to 3.

[0059] In general formula (8), R4 is not particularly limited as long as it is a group containing a hydrocarbon group having 1 to 8 carbon atoms, and may contain a heteroatom. R3 may be saturated or unsaturated, branched or linear, or may have a ring structure. Specific examples of the hydrocarbon group having 1 to 8 carbon atoms include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and octyl; branched alkyl groups such as isopropyl, isobutyl, isopentyl, and isohexyl; cycloalkyl groups such as cyclobutyl, cyclopentyl, and cyclohexyl; cycloalkylalkyl groups such as cyclobutylmethyl, cyclopentylmethyl, cyclohexylmethyl, cyclobutylethyl, cyclopentylethyl, cyclohexylethyl, cyclobutylpropyl, cyclopentylpropyl, cyclobutylbutyl, and cyclopentylbutyl; and alkenyl groups such as propenyl, butenyl, pentenyl, and hexenyl. Among these, branched or straight chain alkyl groups are preferred, and straight chain alkyl groups are more preferred.

[0060] Furthermore, the group containing a hydrocarbon group having 1 to 8 carbon atoms in R4 may contain a heteroatom, such as one or more selected from the group consisting of a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of groups containing a hydrocarbon group having 1 to 8 carbon atoms and containing a heteroatom include those in which one or more hydrogen atoms of the above-mentioned hydrocarbon group having 1 to 8 carbon atoms are substituted with a substituent containing a heteroatom. Examples of the substituent containing a heteroatom include one or more selected from the group consisting of a hydroxy group (-OH), an amino group (-NH2), and a thiol group (-SH). Groups containing a hydrocarbon group having 1 to 8 carbon atoms substituted with a substituent containing a heteroatom include Examples include hydroxyalkyl groups such as a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, a hydroxypentyl group, a hydroxyhexyl group, a hydroxyheptyl group, and a hydroxyoctyl group; dialkylamino groups such as a dimethylamino group, a diethylamino group, a dipropylamino group, and a dibutylamino group; azapropyl group, azabutyl group, azapentyl group, azahexyl group, N,N-dimethylaminobutyl group, N,N-dimethylaminopropyl group, N,N-dimethylaminoethyl group, and N,N-dimethylaminomethyl group. azaalkyl groups such as an N,N-diethylaminobutyl group, an N,N-diethylaminopropyl group, an N,N-diethylaminoethyl group, or an N,N-diethylaminomethyl group; azaalkenyl groups such as an azapropenyl group, an azabutenyl group, an azapentenyl group, an azahexenyl group, an N,N-dimethylaminopropenyl group, an N,N-dimethylaminobutenyl group, an N,N-dimethylaminohexenyl group, or an N,N-diethylaminopropenyl group; an oxaethyl group, an oxapropyl group, an oxabutyl group, an oxapentyl group, an oxahexyl group, or an oxaheptyl group. oxaalkyl groups such as oxapropenyl group, oxabutenyl group, oxopentenyl group, oxahexenyl group, oxaheptenyl group, and oxaoctenyl group; oxaalkyl groups such as thiobutyl group, thiopentyl group, thiohexyl group, thioheptyl group, and thiooctyl group; thioalkenyl groups such as thiopentenyl group, thiohexenyl group, thioheptenyl group, and thiooctenyl group; hydroxyethoxyethyl group, hydroxyethoxypropyl group, hydroxyethoxybutyl group, and hydroxypropoxyethyl group, Examples include hydroxyalkoxyalkyl groups such as hydroxypropoxypropyl group and hydroxypropoxybutyl group; alkoxyalkoxyalkyl groups such as methoxyethoxyethyl group, methoxyethoxypropyl group, methoxyethoxybutyl group, methoxypropoxyethyl group, methoxypropoxypropyl group and methoxypropoxybutyl group; dihydroxyalkyl groups such as dihydroxyethyl group, dihydroxypropyl group and dihydroxybutyl group; and polyhydroxyalkyl groups such as the group obtained by removing the amino group (-NH2-) from D-glucamine.

[0061] The number of carbon atoms in the hydrocarbon group having 1 to 8 carbon atoms in R4 is not particularly limited, and may be, for example, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 6 or more, or 8 or less, 7 or less, 6 or less, 5 or less, 4 or less, or 3 or less, or any compatible combination thereof.Specifically, the number of carbon atoms in the hydrocarbon group having 1 to 8 carbon atoms in R4 may be, for example, 1 to 8, 2 to 7, 3 to 6, 4 to 5, 6 to 8, 1 to 4, or 2 to 3.

[0062] The amine B may be used alone or in combination of two or more.

[0063] The amount of amine B charged is not particularly limited, and may be, for example, 30 mol% or more, 32 mol% or more, or 35 mol% or more, or 75 mol% or less, 70 mol% or less, or 65 mol% or less, relative to the number of moles of the succinimide-derived monomer units. Specific examples of the amount of amine B charged may be 30 mol% to 75 mol%, 32 mol% to 70 mol%, or 35 mol% to 65 mol%. Furthermore, when step (b) is carried out after step (a), the amount of amine B charged is preferably greater than the amount required for the reaction in order to promote the reaction in step (b).

[0064] With regard to the polymer containing a monomer unit derived from succinimide to be subjected to step (b), the explanation in the above section [Polymer containing a monomer unit derived from succinimide] is incorporated herein by reference.

[0065] The solvent (reaction solvent) in step (b) is not particularly limited as long as it is a solvent that can promote the reaction of step (b), and examples thereof include a solvent containing one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and may further contain a compound having at least one hydroxyl group. With regard to the one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the compound having at least one hydroxyl group, the description of the one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the description of the compound having at least one hydroxyl group in step (a) is incorporated by reference.

[0066] The solvent in step (b) may contain one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group, as long as the reaction in step (b) can proceed. Specifically, the solvent may contain, for example, an aprotic polar organic solvent such as dimethylacetamide (DMAc), dimethylimidazolidinone (DMI), sulfolane, 3-methoxy-N,N-dimethylpropanamide, or 3-butoxy-N,N-dimethylpropanamide.

[0067] When the production method of the present disclosure further includes step (b), steps (a) and (b) may be performed in any order. For example, step (b) may be performed before step (a), after step (a), or simultaneously with step (a). When step (b) is carried out before step (a), for example, after step (b), amine A may be further added to the reaction system in step (a), and a solvent may or may not be further added. When step (b) is carried out after step (a), for example, after step (a), amine B may be further added to the reaction system in step (b), and a solvent may or may not be further added. When step (b) is carried out simultaneously with step (a), for example, amine A and amine B may be added to the solvent in step (a). The order of addition of amine A and amine B is not particularly limited. Amine A may be added first and then amine B, or amine B may be added first and then amine A, or amine A and amine B may be added simultaneously. Furthermore, when step (b) is carried out simultaneously with step (a), this means that step (b) is carried out in the middle of step (a) and step (a) is carried out in the middle of step (b).

[0068] The solvent in step (b) may be of a different type from the solvent in step (a), or may be of the same type.

[0069] The concentration of the polymer containing a monomer unit derived from succinimide in the solvent in step (b) is not particularly limited, and may be, for example, 1.0 wt % or more, 3.0 wt % or more, 5.0 wt % or more, 10.0 wt % or more, 15.0 wt % or more, or 20.0 wt % or more, or 50.0 wt % or less, 40.0 wt % or less, 30.0 wt % or less, 20.0 wt % or less, 15.0 wt % or less, or 10.0 wt % or less, or any compatible combination thereof. The concentration of the polymer containing a monomer unit derived from succinimide in the solvent in step (b) may be, for example, 1.0 wt % to 50.0 wt %, 3.0 wt % to 40.0 wt %, 5.0 wt % to 30.0 wt %, 10.0 wt % to 20.0 wt %, 15.0 wt % to 50.0 wt %, 20.0 wt % to 40.0 wt %, 1.0 wt % to 15.0 wt %, or 3.0 wt % to 10.0 wt %.

[0070] Step (b) can be carried out by a known method. Specific procedures for step (b) include, for example, dissolving a polymer containing a succinimide-derived monomer unit in a solvent, adding dropwise a solution of amine B to the solution, and reacting the resulting mixture under a predetermined temperature condition.

[0071] The temperature conditions for step (b) are not particularly limited as long as the progress of the reaction can be substantially maintained. Step (b) may be carried out at a temperature of, for example, 5° C. or higher, 10° C. or higher, 15° C. or higher, 20° C. or higher, 25° C. or higher, 30° C. or higher, or 35° C. or higher, or at a temperature of 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, 110° C. or lower, 100° C. or lower, 95° C. or lower, 90° C. or lower, 85° C. or lower, 80° C. or lower, 75° C. or lower, 70° C. or lower, 65° C. or lower, or 60° C. or lower. Step (b) may be carried out at a temperature of, for example, 5°C to 150°C, 10°C to 140°C, 15°C to 130°C, 20°C to 120°C, 25°C to 110°C, 30°C to 100°C, 35°C to 95°C, 5°C to 90°C, 10°C to 85°C, 15°C to 80°C, 20°C to 75°C, 25°C to 70°C or less, 30°C to 65°C, or 35°C to 60°C.

[0072] The reaction time of step (b) is not particularly limited as long as the reaction of step (b) can proceed, but may be, for example, 5 minutes or more, 10 minutes or more, 20 minutes or more, 30 minutes or more, 1 hour or more, 2 hours or more, 3 hours or more, 4 hours or more, 5 hours or more, 6 hours or more, or 7 hours or more, or 15 hours or less, 10 hours or less, 9 hours or less, 8 hours or less, 7 hours or less, 6 hours or less, 5 hours or less, 4 hours or less, 3 hours or less, 2 hours or less, 1 hour or less, or 30 minutes or less, or any combination thereof that does not contradict. Specifically, it may be, for example, 5 minutes to 15 hours, 10 minutes to 10 hours, 20 minutes to 9 hours, 30 minutes to 8 hours, 1 hour to 7 hours, 2 hours to 6 hours, 3 hours to 5 hours, 4 hours to 15 hours, 5 hours to 10 hours, 6 hours to 9 hours, 7 hours to 8 hours, 5 minutes to 4 hours, 10 minutes to 3 hours, 20 minutes to 2 hours, 30 minutes to 1 hour, or 5 minutes to 30 minutes.

[0073] The reaction product obtained in step (b) is a polymer containing succinimide-derived monomer units in which some of the succinimide-derived monomer units have been modified with amine B.

[0074] The molar ratio of the amount of amine A charged to the amount of amine B charged is not particularly limited, and may be, for example, 25 / 75 to 60 / 40, or 30 / 70 to 60 / 40.

[0075] [Step (c)] The production method of the present disclosure may further include the following step (c): Step (c): A step of crosslinking the polymer containing the succinimide-derived monomer units with a crosslinking agent.

[0076] In step (c), a crosslinked structure is formed in the polymer by a crosslinking agent. The crosslinked structure can be formed by any crosslinking agent capable of forming a crosslinked moiety. The crosslinking agent is not particularly limited, but examples thereof include crosslinking agents that form amide bonds as crosslinked moieties, and specifically, polyfunctional amines.

[0077] The polyfunctional amine is preferably an amine having at least two amino groups, one or more of which is selected from the group consisting of primary and secondary amino groups. Examples of diamines include aliphatic diamines such as ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,2-butanediamine, 1,3-butanediamine, 1,4-butanediamine, 1,2-pentanediamine, 1,3-pentanediamine, 1,4-pentanediamine, 1,5-pentanediamine, 1,2-hexanediamine, 1,3-hexanediamine, 1,4-hexanediamine, 1,5-hexanediamine, hexamethylenediamine, 1,7-pentanediamine, 1,8-octanediamine, 1,10-diaminodecane (DAD), and 1,12-dodecyldiamine; Examples of suitable polyfunctional amines include aliphatic diamines containing an aromatic ring, such as norbornene diamine; alicyclic diamines, such as norbornene diamine; ether-based diamines, such as 1,2-bis(2-aminoethoxy)ethane (AEE), diethylene glycol bis(3-aminopropyl) ether (bis[2-(3-aminopropoxy)ethyl ether (APEE)), polyoxyethylene diamine, and polyoxypropylene diamine; amino acids and derivatives thereof having an amino group in the side chain, such as lysine and ornithine; and monoamino compounds linked by disulfide bonds, such as cystine and cystamine, and derivatives thereof. The polyfunctional amine preferably contains one or more selected from the group consisting of aliphatic diamines, alicyclic diamines, and ether-based diamines. The polyfunctional amine preferably does not contain the above amino acids and their derivatives. The polyfunctional amine is preferably one or more selected from the group consisting of aliphatic diamines and ether-based diamines, from the viewpoints of having a flexible structure that makes it difficult for insoluble matter to be generated during the crosslinking reaction and of making the crosslinking reaction easier to control.

[0078] Examples of polyfunctional amines other than diamines include tris(2-aminoalkyl)amines (where the carbon atom number of the alkyl is preferably 1 to 5, and more preferably 2 to 4), such as tris(2-aminoethyl)amine (TREN) and tris(3-aminopropyl)amine; diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

[0079] Among these, preferred examples of polyfunctional amines include 1,2-bis(2-aminoethoxy)ethane (AEE), bis[2-(3-aminopropoxy)ethyl ether (APEE)], tris(2-aminoethyl)amine (TREN), 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, hexamethylenediamine, 1,7-pentanediamine, 1,8-octanediamine, 1,10-diaminodecane (DAD), and 1,12-dodecyldiamine.

[0080] The crosslinking agent may be used alone or in combination of two or more.

[0081] The amount of the crosslinking agent used is not particularly limited, but may be, for example, 0.1 mol% or more, 0.3 mol% or more, or 0.5 mol% or more, or 2.0 mol% or less, 1.8 mol% or less, or 1.7 mol% or less, relative to the number of moles of the succinimide-derived monomer units. Specifically, the amount of the crosslinking agent used may be, for example, 0.1 mol% to 2.0 mol%, 0.3 mol% to 1.8 mol%, or 0.5 mol% to 1.7 mol%.

[0082] With regard to the polymer containing a monomer unit derived from succinimide to be subjected to step (c), the explanation in the above section [Polymer containing a monomer unit derived from succinimide] is incorporated herein by reference.

[0083] The solvent (reaction solvent) in step (c) is not particularly limited as long as it is a solvent that can promote the reaction of step (c), and examples thereof include a solvent containing one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and may further contain a compound having at least one hydroxyl group. With regard to the one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the compound having at least one hydroxyl group, the description of the one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and the description of the compound having at least one hydroxyl group in step (a) is incorporated by reference.

[0084] The solvent in step (c) may contain one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group, as long as the reaction in step (c) can proceed. Specifically, the solvent may contain, for example, an aprotic polar organic solvent such as dimethylacetamide (DMAc), dimethylimidazolidinone (DMI), sulfolane, 3-methoxy-N,N-dimethylpropanamide, or 3-butoxy-N,N-dimethylpropanamide.

[0085] When the manufacturing method of the present disclosure further includes step (c), steps (a) and (c) may be performed in any order. For example, step (c) may be performed before step (a); It may be carried out after step (a) or simultaneously with step (a).

[0086] When the manufacturing method of the present disclosure further includes steps (b) and (c), steps (a), (b), and (c) may be performed in any order. For example, steps (a), (b), and (c) may be performed in this order; steps (a), (c), and (b); steps (b), (a), and (c); steps (b), (c), and (a); steps (c), (a), and (b); or steps (c), (b), and (a). Furthermore, two or more steps selected from the group consisting of steps (a), (b), and (c) may be performed simultaneously.

[0087] In particular, it is preferable to perform the steps (c), (a), and (b) in this order. Therefore, the production method of the present disclosure preferably includes the following steps (c), (a), and (b). Step (c): A step of crosslinking the polymer containing the succinimide-derived monomer units with a crosslinking agent. Step (a): A step of modifying the reaction product obtained in step (c) with an amine represented by general formula (1) in the presence of a solvent, The solvent contains one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group. Step (b): A step of modifying the reaction product obtained in step (a) with one or more amines selected from the group consisting of amines represented by general formula (7) and amines represented by general formula (8).

[0088] When step (c) is carried out before step (a), for example, after step (c), amine A may be further added to the reaction system in step (a), and a solvent may or may not be further added. When step (c) is carried out after step (a), for example, after step (a), a crosslinking agent may be further added to the reaction system in step (c), and a solvent may or may not be further added.

[0089] When step (c) is carried out simultaneously with step (a), for example, amine A and a crosslinking agent may be added to the solvent used in step (a). The order of addition of amine A and crosslinking agent is not particularly limited. Amine A may be added first and then the crosslinking agent, or the crosslinking agent may be added first and then the amine A, or amine A and the crosslinking agent may be added simultaneously. Furthermore, when step (c) is carried out simultaneously with step (a), this includes cases where step (c) is carried out during step (a) and cases where step (a) is carried out during step (c).

[0090] When step (c) is carried out before step (b), for example, after step (c), amine B may be further added to the reaction system in step (b), and a solvent may or may not be further added. When step (c) is carried out after step (b), for example, after step (b), a crosslinking agent may be further added to the reaction system in step (c), and a solvent may or may not be further added.

[0091] When step (c) is carried out simultaneously with step (b), for example, amine B and a crosslinking agent may be added. The order of addition of amine B and a crosslinking agent is not particularly limited. Amine B may be added first and then the crosslinking agent, or the crosslinking agent may be added first and then the amine B, or amine B and the crosslinking agent may be added simultaneously. In addition, when step (c) is carried out simultaneously with step (b), The phrase "when step (c) is carried out in the middle of step (b)" includes the case where step (c) is carried out in the middle of step (b) and the case where step (b) is carried out in the middle of step (c).

[0092] The solvent in step (c) may be of a different type from the solvent in step (a), or may be the same type as the solvent in step (a).Furthermore, the solvent in step (c) may be of a different type from the solvent in step (b), or may be the same type as the solvent in step (b).

[0093] The concentration of the polymer containing a monomer unit derived from succinimide in the solvent in step (c) is not particularly limited, and may be, for example, 1.0 wt % or more, 3.0 wt % or more, 5.0 wt % or more, 10.0 wt % or more, 15.0 wt % or more, or 20.0 wt % or more, or 50.0 wt % or less, 40.0 wt % or less, 30.0 wt % or less, 20.0 wt % or less, 15.0 wt % or less, or 10.0 wt % or less, or any compatible combination thereof. The concentration of the polymer containing a monomer unit derived from succinimide in the solvent in step (a) may be, for example, 1.0 wt % to 50.0 wt %, 3.0 wt % to 40.0 wt %, 5.0 wt % to 30.0 wt %, 10.0 wt % to 20.0 wt %, 15.0 wt % to 50.0 wt %, 20.0 wt % to 40.0 wt %, 1.0 wt % to 15.0 wt %, or 3.0 wt % to 10.0 wt %.

[0094] Step (c) can be carried out by a known method. Specific procedures for step (c) include, for example, dissolving a polymer containing a monomer unit derived from succinimide in a solvent, adding dropwise a solvent solution containing a crosslinking agent, and reacting the resulting mixture under a predetermined temperature condition.

[0095] The temperature conditions for step (c) are not particularly limited as long as the progress of the reaction can be substantially maintained. Step (c) may be carried out at a temperature of, for example, 5° C. or higher, 10° C. or higher, 15° C. or higher, 20° C. or higher, 25° C. or higher, 30° C. or higher, or 35° C. or higher, or at a temperature of 150° C. or lower, 140° C. or lower, 130° C. or lower, 120° C. or lower, 110° C. or lower, 100° C. or lower, 95° C. or lower, 90° C. or lower, 85° C. or lower, 80° C. or lower, 75° C. or lower, 70° C. or lower, 65° C. or lower, or 60° C. or lower. Step (c) may be carried out at a temperature of, for example, 5°C to 150°C, 10°C to 140°C, 15°C to 130°C, 20°C to 120°C, 25°C to 110°C, 30°C to 100°C, 35°C to 95°C, 5°C to 90°C, 10°C to 85°C, 15°C to 80°C, 20°C to 75°C, 25°C to 70°C or less, 30°C to 65°C, or 35°C to 60°C.

[0096] The reaction time for step (c) is not particularly limited as long as the reaction of step (c) can proceed, but may be, for example, 5 minutes or more, 10 minutes or more, 20 minutes or more, 30 minutes or more, 1 hour or more, 2 hours or more, 3 hours or more, 4 hours or more, 5 hours or more, 6 hours or more, or 7 hours or more, or 15 hours or less, 10 hours or less, 9 hours or less, 8 hours or less, 7 hours or less, 6 hours or less, 5 hours or less, 4 hours or less, 3 hours or less, 2 hours or less, 1 hour or less, or 30 minutes or less, or any combination thereof that does not contradict. Specifically, it may be, for example, 5 minutes to 15 hours, 10 minutes to 10 hours, 20 minutes to 9 hours, 30 minutes to 8 hours, 1 hour to 7 hours, 2 hours to 6 hours, 3 hours to 5 hours, 4 hours to 15 hours, 5 hours to 10 hours, 6 hours to 9 hours, 7 hours to 8 hours, 5 minutes to 4 hours, 10 minutes to 3 hours, 20 minutes to 2 hours, 30 minutes to 1 hour, or 5 minutes to 30 minutes.

[0097] The reaction product obtained in step (c) is a polymer containing succinimide-derived monomer units in which at least a portion of the succinimide-derived monomer units has been crosslinked.

[0098] In the production method of the present disclosure, unreacted imide rings may remain in the resulting polyaspartic acid derivative. The production method of the present disclosure may further include a step of modifying the polymer containing the succinimide-derived monomer unit with a monoamine other than amine A and amine B. In this case, the step (a), step (b) and step (c) may be carried out in the same manner. c) may be performed in any order. When this step is included, the total amount of amine A and amine B charged may be 80.0 mol% or more, 90.0 mol% or more, or 95.0 mol% or more, or 99.0 mol% or less, 95.0 mol% or less, or 90.0 mol% or less, or any compatible combination thereof, based on the total amount of amine A, amine B, and monoamines other than amine A and amine B charged. Specifically, the amount may be, for example, 80.0 mol% to 99.0 mol%, 90.0 mol% to 95.0 mol%, or 80.0 mol% to 90.0 mol%.

[0099] [Isolation of polyaspartic acid derivatives] The production method of the present disclosure may include a step of isolating the produced polyaspartic acid derivative from the reaction solution after completion of the reaction. The isolation method is not particularly limited as long as it can isolate the polyaspartic acid derivative with the desired purity, and any known or commonly used method may be used. Generally, known or commonly used isolation procedures such as concentration, recrystallization, or reprecipitation are used.

[0100] A specific example of the isolation method is a method in which, after completion of the reaction, an excess of a poor solvent (e.g., ethyl acetate, acetone, methyl ethyl ketone, acetonitrile, methyl ethyl ketone, water, etc.) is added to the reaction solution in which the reaction product is dissolved at an appropriate temperature, the precipitated reaction product is isolated by decantation, filtration, suction filtration, etc., and the crystals are thoroughly washed with a poor solvent that does not dissolve the crystals, followed by drying. Another specific example is a method in which, after completion of the reaction, the reaction solution in which the reaction product is dissolved is added to an excess of the same poor solvent as above at an appropriate temperature, and the precipitated reaction product is isolated, washed, and dried in the same manner as above.

[0101] The polyaspartic acid derivative produced by the production method of the present disclosure may be used as is without isolation, as a polyaspartic acid derivative, as a reaction solution after the completion of the reaction. If necessary, only some unreacted raw materials other than the solvent may be removed, and the polyaspartic acid derivative may be used. Alternatively, the concentration of the reaction solution after the completion of the reaction may be adjusted by increasing or decreasing the amount of solvent, and the resulting polyaspartic acid derivative may be used.

[0102] [Polyaspartic acid derivatives] The polyaspartic acid derivatives produced by the production method of the present disclosure are polymers formed by peptide bonds of aspartic acid. The amide bonds in the main chain of polyaspartic acid may be α- or β-bonds. Furthermore, these bond types may be the same or different for each structural unit.

[0103] The polyaspartic acid derivative produced by the production method of the present disclosure contains an α- or β-polyaspartic acid monomer unit AU (also referred to as a "monomer unit AU") represented by the above general formula (3). The polyaspartic acid derivative containing the monomer unit AU is obtained by step (a). One molecule of the polyaspartic acid derivative may contain one type of monomer unit AU alone or two or more types.

[0104] The amount of the monomer unit AU present in the constituent monomers of the polyaspartic acid derivative is not particularly limited, but may be, for example, 20 mol% or more, 25 mol% or more, or 30 mol% or more, or 60 mol% or less, 58 mol% or less, or 57 mol% or less. Specifically, the amount of the monomer unit AU present may be, for example, 20 mol% to 60 mol%, 25 mol% to 58 mol%, or 30 mol% to 57 mol%. The amount of the monomer unit AU present can be adjusted by the amount of amine A and other raw materials charged.

[0105] The abundance of the monomer unit AU can be, for example, 1 It can be calculated from HNMR. can be calculated from the obtained NMR spectrum, for example, using the following formula: Abundance of monomer unit AU (mol %)=(peak integral value of methyl group of amine A / 3)×100 / ((peak integral value of methyl group of amine A / 3)+(peak integral value of methylene group of amine B / 2)+(peak integral value of methine group of succinimide))

[0106] The polyaspartic acid derivative produced by the production method of the present disclosure may further contain one or more selected from the group consisting of α- or β-polyaspartic acid monomer units B'-U represented by the above general formula (4) and α- or β-polyaspartic acid monomer units B''-U represented by the general formula (5) (these are also collectively referred to as "monomer units BU"). The polyaspartic acid derivative containing the monomer units BU is obtained by step (b). One molecule of the polyaspartic acid derivative may contain one type of monomer unit BU alone or two or more types.

[0107] The amount of the monomer units BU present in the constituent monomers of the polyaspartic acid derivative is not particularly limited, but may be, for example, 30 mol% or more, 32 mol% or more, or 35 mol% or more, or 60 mol% or less, 50 mol% or less, or 45 mol% or less. Specific examples of the amount of the monomer units BU present may be 30 mol% to 80 mol%, 32 mol% to 75 mol%, or 35 mol% to 70 mol%. The amount of the monomer units BU present can be adjusted by the amount of amine B and other raw materials charged.

[0108] The amount of the monomer unit BU present can be, for example, 1 It can be calculated from HNMR. Specifically, it can be calculated from the obtained NMR spectrum, for example, using the following formula: Abundance of monomer unit BU (mol %)=(peak integral value of methylene group of amine B / 2)×100 / ((peak integral value of methyl group of amine A / 3)+(peak integral value of methylene group of amine B / 2)+(peak integral value of methine group of succinimide))

[0109] In the polyaspartic acid derivative, the ratio of the amount (mol %) of the monomer unit AU to the amount (mol %) of the monomer unit BU (also expressed as (AU) / (BU)) is not particularly limited, and may be, for example, 25 / 75 to 60 / 40, or 30 / 70 to 60 / 40.

[0110] (AU) / (BU) is, for example,1 It can be calculated from HNMR. Specifically, it can be calculated from the obtained NMR spectrum, for example, using the following formula: (AU) / (BU)=(peak integral of methyl group of amine A / 3) / (peak integral of methylene group of amine B / 2)

[0111] The polyaspartic acid derivative produced by the production method of the present disclosure may contain an α- or β-polyaspartic acid monomer unit Crosslink-U (also referred to as a "monomer unit Crosslink-U") represented by the above general formula (6). The polyaspartic acid derivative containing the monomer unit Crosslink-U is obtained by step (c).

[0112] The amount of crosslinking in the polyaspartic acid derivative (i.e., the amount of the monomer unit Crosslink-U present in the constituent monomers of the polyaspartic acid derivative) is not particularly limited, but may be, for example, 0.1 mol% or more, 0.3 mol% or more, or 0.5 mol% or more, or 2.0 mol% or less, 1.8 mol% or less, or 1.7 mol% or less. Specific examples of the amount of crosslinking may be 0.1 mol% to 2.0 mol%, 0.3 mol% to 1.8 mol%, or 0.5 mol% to 1.7 mol%. The amount of crosslinking can be adjusted by the amount of crosslinking agent and the amount of each of the other raw materials charged.

[0113] The crosslinking amount is, for example, the ratio of the moles of the crosslinking agent to the moles of the monomer units derived from succinimide. It can be calculated from the ratio (%) of the amount charged (number of moles).

[0114] In the polyaspartic acid derivative produced by the production method of the present disclosure, unreacted succinimide rings may remain, i.e., the polyaspartic acid derivative may contain the monomer unit represented by the above formula (2) (also referred to as "monomer unit CU").

[0115] When the polyaspartic acid derivative contains the monomer units AU, BU, and CU, the ratio of the total abundance (mol %) of the monomer units AU and BU to the abundance (mol %) of the monomer unit CU in the polyaspartic acid derivative (also represented as [(AU)+(BU)] / (CU)) is not particularly limited and may be, for example, 80 / 20 to 99 / 1, 85 / 15 to 98 / 1, 90 / 10 to 98 / 2, or 90 / 10 to 97 / 2.

[0116] [(AU)+(BU)] / (CU), for example, 1 It can be calculated from HNMR. Specifically, it can be calculated from the obtained NMR spectrum, for example, using the following formula: [(AU) + (BU)] / (CU) = [(peak integral of methyl group of amine A / 3) + (peak integral of methylene group of amine B / 2)] / (peak integral of methine group of succinimide)

[0117] The bonding form of the monomer units AU, BU, CU, and Crosslink-U may be any of random, block, and tapered. The bonding form of each of these monomer units may be any of linear, macrocyclic, branched, star, and three-dimensional network structures, but is preferably a linear structure with a slight three-dimensional network structure.

[0118] The polyaspartic acid derivative may contain a monomer unit other than the monomer units AU, BU, CU, and Crosslink-U. For example, the polyaspartic acid derivative may contain a monomer unit in which succinimide is modified with a monoamine other than amine A and amine B.

[0119] The polyaspartic acid derivative may also contain, for example, one or more monomer units selected from the group consisting of a monomer unit represented by the following general formula (9), a monomer unit represented by the following general formula (10), and a monomer unit represented by the following general formula (11).

[0120] [ka] (In the formula, R1 represents a group containing a hydrocarbon group having 3 to 22 carbon atoms which may contain a heteroatom.)

[0121] The monomer unit represented by the general formula (9) is formed by opening the succinimide ring of the monomer unit CU. The carboxylic acid is a carboxylic acid ammonium salt in which the carboxylic acid, which is a monomer formed by the reaction, is bonded to the amine A remaining after step (a). The explanation for R1 in general formula (1) is incorporated herein by reference.

[0122] [ka] (In the formula, R2 represents a group containing a hydrocarbon group having 1 to 16 carbon atoms which may contain a heteroatom.)

[0123] [ka] (In the formula, R3 represents a group containing a hydrocarbon group having 1 to 8 carbon atoms which may contain a heteroatom, and R4 represents a group containing a hydrocarbon group having 1 to 8 carbon atoms which may contain a heteroatom.)

[0124] The monomer unit represented by general formula (10) and the monomer unit represented by general formula (11) are each an ammonium carboxylate salt formed by combining a carboxylic acid, which is a monomer formed by ring-opening the succinimide ring of the monomer unit CU, with the amine B remaining after step (b). The explanation for R2 in general formula (10) is incorporated herein by reference. Furthermore, the explanation for R3 and R4 in general formula (8) is incorporated herein by reference.

[0125] The weight average molecular weight (Mw) of the polyaspartic acid derivative is not particularly limited, and may be, for example, 70,000 or more, 80,000 or more, 100,000 or more, 120,000 or more, 150,000 or more, 200,000 or more, or 250,000 or more, or 1,000,000 or less, 700,000 or less, 600,000 or less, 500,000 or less, 400,000 or less, 300,000 or less, or 200,000 or less, or any compatible combination thereof. Specifically, the weight average molecular weight may be, for example, 70,000 to 1,000,000, 80,000 to 700,000, 100,000 to 600,000, 120,000 to 500,000, 150,000 to 400,000, 200,000 to 500,000, 250,000 to 400,000, or 70,000 to 200,000. The weight average molecular weight can be adjusted by the molecular weight of the polymer containing a monomer unit derived from succinimide, the types of amine A and amine B, the type of solvent used in step (a), etc.

[0126] When an aqueous solution containing 1.5 wt % of a polyaspartic acid derivative and 0.2 wt % of citric acid is prepared, the shear viscosity of the aqueous solution is not particularly limited, and may be, for example, 1000 mPa·s or more, 1500 mPa·s or more, 2000 mPa·s or more, 2500 mPa·s or more, or 3000 mPa·s or more, or 10000 mPa·s or less, 8000 mPa·s or less, 7000 mPa·s or less, 6000 mPa·s or less, or 5000 mPa·s or less. Specifically, the shear viscosity may be, for example, 1000 mPa·s to 10000 mPa·s, 1500 mPa·s to 8000 mPa·s, 2000 mPa·s to 7000 mPa·s, 2500 mPa·s to 6000 mPa·s, or 3000 mPa·s to 5000 mPa·s. The shear viscosity can be adjusted by the molecular weight of the polymer containing the succinimide-derived monomer unit, the types of amine A and amine B, the type of solvent used in step (a), etc. In this disclosure, the shear viscosity refers to the shear viscosity value at a shear rate of 5 (1 / s) after preshearing for 15 seconds at a shear rate of 10 (1 / s) and leaving it to stand for 30 seconds using a rotational rheometer (MCR102, manufactured by Anton Paar) under conditions of a cone plate CP-25, a gap of 0.106 mm, and a measurement temperature of 25°C.

[0127] When an aqueous solution containing 1.5 wt % of a polyaspartic acid derivative and 0.2 wt % of citric acid is prepared and then stored at 50°C for two months, the shear viscosity of the aqueous solution is not particularly limited, and may be, for example, 900 mPa·s or more, 1000 mPa·s or more, 1500 mPa·s or more, 2000 mPa·s or more, 2500 mPa·s or more, or 3000 mPa·s or more, or 10000 mPa·s or less, 8000 mPa·s or less, 7000 mPa·s or less, 6000 mPa·s or less, or 5000 mPa·s or less. Specifically, the shear viscosity may be, for example, 900 mPa·s to 10,000 mPa·s, 1,000 mPa·s to 8,000 mPa·s, 1,500 mPa·s to 7,000 mPa·s, 2,000 mPa·s to 6,000 mPa·s, 2,500 mPa·s to 5,000 mPa·s, or 3,000 mPa·s to 10,000 mPa·s. The shear viscosity can be adjusted by the molecular weight of the polymer containing the succinimide-derived monomer unit, the types of amine A and amine B, the type of solvent used in step (a), etc.

[0128] After preparing an aqueous solution containing 1.5 wt% of a polyaspartic acid derivative and 0.2 wt% of citric acid, the shear viscosity retention of the aqueous solution after storage at 50°C for two months is not particularly limited, but may be, for example, 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more; or 100% or less, 97% or less, 95% or less, 90% or less, or 85% or less, or any compatible combination thereof. Specifically, the viscosity retention may be, for example, 70% to 100%, 75% to 97%, 80% to 95%, 85% to 90%, 90% to 100%, or 70% to 85%. The viscosity retention can be adjusted by the molecular weight of the polymer containing the succinimide-derived monomer unit, the types of amine A and amine B, the type of solvent used in step (a), and the like. The shear viscosity retention rate here refers to the ratio (%) of the shear viscosity of the aqueous solution after storage at 50°C for 2 months to the shear viscosity immediately after preparation of the aqueous solution.

[0129] The polyaspartic acid derivative produced by the production method of the present disclosure has a high molecular weight and a high viscosity, and therefore is suitable for use as a thickener. In addition, since it has excellent stability when stored for a long period of time in the form of an aqueous solution, it can be used as a composition containing the polyaspartic acid derivative and water. The polyaspartic acid derivative can be used for any desired purpose, for example, for external skin preparations, specifically, cosmetics, quasi-drugs, and pharmaceuticals. [Example]

[0130] The present invention will be described in detail below with reference to examples, but the present disclosure is not limited thereto.

[0131] [Example 1] The polyaspartic acid derivative of Example 1 was prepared according to the following procedure.

[0132] <Synthesis of Polysuccinimide (PSI)> 160 parts of aspartic acid (YIXING QIANCHENG BIO-ENGINEERING Co., Ltd., 99.97% purity) and 83 parts of 85% phosphoric acid were mixed in a mortar, transferred to a tray, and reacted at 190°C and 1.3 kPa for 5 hours. The reaction mixture was pulverized, washed with distilled water until the filtrate became neutral, and then vacuum dried at 80°C to obtain 115 parts of polysuccinimide (PSI) with a weight-average molecular weight of 70,000. The weight-average molecular weight of PSI was measured using the measurement method described below.

[0133] <Synthesis of polyaspartic acid derivatives> 10.0 g of PSI and 60.0 g of dimethylformamide (DMF) were placed in a reaction vessel and completely dissolved by heating at 60°C. Ethanol (EtOH) was added while stirring at 60°C. After 10.0 g of 1,2-bis(2-aminoethoxy)ethane (AEE) was added dropwise over 30 minutes, a mixture of 0.228 g (1.5 mol % per mole of succinimide units) of 1,2-bis(2-aminoethoxy)ethane (AEE) as a crosslinker and 2.06 g of DMF was added and allowed to react for 2 hours. Next, a mixture of 10.3 g (54 mol % per mole of succinimide units) of Farmin 20D (a mixture of 1% decylamine, 96% dodecylamine, and 3% tetradecylamine, manufactured by Kao Corporation) as amine A and 10.3 g of 99.5 wt % EtOH was added dropwise and allowed to react for 30 minutes at 60°C. Furthermore, 3.45 g of 3-amino-1-propanol (PA) (44.5 mol % per mole of succinimide units) was added as amine B, and the reaction was allowed to proceed for 7 hours while maintaining the temperature inside the reaction vessel at 60°C. The reaction vessel was then cooled, and once it reached room temperature, the reaction solution was poured into 1,080 g of ethyl acetate (EA) with stirring to precipitate the reaction product, and the solid was recovered by filtration. The recovered solid was further washed in 540 g of ethyl acetate (EA) with stirring, and the solid was recovered by filtration. The recovered solid was dried at 60°C under reduced pressure for 12 hours, yielding 22.2 g of the polyaspartic acid derivative of Example 1.

[0134] [Examples 2 to 15] The polyaspartic acid derivatives of Examples 2 to 15 were obtained in the same manner as in Example 1, except that the raw materials and solvent, the temperature when dissolving PSI in the solvent, and the reaction temperature were changed as shown in Table 1. In Table 1, the purities of n-propanol, isopropanol, and propylene glycol were 99.7% by weight, 99.7% by weight, and 99.0% by weight, respectively.

[0135] [Comparative Example 1] 10.0 g of PSI and 60.0 g of dimethylformamide (DMF) were placed in a reaction vessel and completely dissolved by heating at 60°C. While stirring at 60°C, a mixture of 0.228 g (1.5 mol% per mole of succinimide units) of 1,2-bis(2-aminoethoxy)ethane (AEE) as a crosslinking agent and 2.06 g of DMF was added and reacted for 7 hours. Next, a mixture of 10.3 g (54 mol% per mole of succinimide units) of Farmin 20D as amine A and 2.00 g of DMF was added and heated at 60°C. The mixture was allowed to react for 30 minutes. Furthermore, 3.45 g of 3-amino-1-propanol (PA) (44.5 mol % relative to 1 mole of succinimide units) was added as amine B, and the reaction was allowed to proceed for 7 hours while maintaining the temperature inside the reaction vessel at 60°C. The reaction vessel was then cooled, and once it reached room temperature, the reaction solution was poured into 1,080 g of ethyl acetate (EA) with stirring to precipitate the reaction product, and the solid was recovered by filtration. The recovered solid was further washed with 540 g of ethyl acetate (EA) with stirring, and the solid was recovered by filtration. The recovered solid was dried at 60°C under reduced pressure for 12 hours, yielding 22.2 g of the polyaspartic acid derivative of Comparative Example 1.

[0136] [Comparative Examples 2 to 4] Polyaspartic acid derivatives of Comparative Examples 2 to 4 were obtained in the same manner as in Comparative Example 1, except that the solvent, the temperature at which PSI was dissolved in the solvent, and the reaction temperature were changed as shown in Table 1.

[0137] [Table 1]

[0138] <Measurement of Weight-Average Molecular Weight of PSI and Polyaspartic Acid Derivative> In the measurement of the weight-average molecular weight of PSI, the polystyrene-equivalent value was determined by the GPC method (differential refractometer). For the measurement, a G1000HHR column (TSKgel (registered trademark), manufactured by Tosoh Corporation), a G4000HHR column (TSKgel (registered trademark), manufactured by Tosoh Corporation), or a GMHHR-H column (TSKgel (registered trademark), manufactured by Tosoh Corporation) was used. As the eluent, dimethylformamide containing 10 mM lithium bromide was used. Also, the weight-average molecular weights of the polyaspartic acid derivatives in each example and comparative example were measured in the same manner. The results are shown in Table 1.

[0139] <Measurement of Viscosity> The obtained polyaspartic acid derivatives of the examples and comparative examples were each dissolved in ion-exchanged water at 80 °C so that the concentration became 1.8% by weight, and then the pH was adjusted to 7 with a 0.2% by weight aqueous citric acid solution, and further adjusted with water at pH 7 so that the concentration became 1.5% by weight to obtain each sample. The shear viscosity of each obtained sample was measured using a rotational rheometer (MCR102, manufactured by Anton Paar). Specifically, under the conditions of a cone plate CP-25, a gap of 0.106 mm, and a measurement temperature of 25 °C, preshear was performed at a shear rate of 10 (1 / s) for 15 seconds and then left standing for 30 seconds, and then the shear viscosity at a shear rate of 5 (1 / s) was measured. The results are shown in Table 1.

[0140] <Stability Test> After storing the above-obtained viscosity measurement samples in a sealed state in a constant-temperature container at 50 °C for 2 months, the viscosity was measured in the same manner as in the above <Measurement of Viscosity>. The evaluation was performed using the post-test viscosity retention rate (%) of the following formula. Post-test viscosity retention rate (%) = (viscosity after stability test) / (viscosity before stability test) × 100

[0141] As shown in Table 1, in Examples 1 to 13, in which the temperature in step (a) was 60°C, polyaspartic acid derivatives with higher weight average molecular weights and higher viscosity were obtained compared to Comparative Examples 1 to 3, in which the temperature in step (a) was also 60°C. Similarly, in Example 14, in which the temperature in step (a) was 40°C, polyaspartic acid derivatives with higher weight average molecular weights and higher viscosity were obtained compared to Comparative Example 4, in which the temperature in step (a) was also 40°C. Furthermore, in Examples 1 to 14, the viscosity retention after testing was higher and stability was superior compared to Comparative Examples 1 to 4. These results demonstrate that polyaspartic acid derivatives with high molecular weights and excellent storage stability can be obtained by using a solvent such as DMF in combination with a compound having at least one hydroxyl group.

Claims

1. A method for producing a polyaspartic acid derivative, comprising the following step (a): Step (a): A step of modifying a polymer containing a succinimide-derived monomer unit with an amine represented by the following general formula (1) in the presence of a solvent, R １ -NH ２ (1) (In the formula, R １ represents a group containing a hydrocarbon group having 3 to 22 carbon atoms which may contain a heteroatom. The solvent contains one or more selected from the group consisting of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, and a compound having at least one hydroxyl group.

2. The method of claim 1 , wherein step (a) is carried out at 40° C. or higher.

3. The method according to claim 1 or 2, wherein step (a) is carried out at 150°C or less.

4. 3. The method according to claim 1, wherein the ratio of the number of moles of hydroxyl groups of the compound having at least one hydroxyl group to the number of moles of monomer units derived from succinimide in the solvent in step (a) is 1.0 to 10.0.

Images