JP2023053737A - thickening composition - Google Patents

Abstract

To provide a thickening composition that can exhibit high thickening effect even with a small amount of addition.SOLUTION: A composition comprises a crosslinked polymer. The crosslinked polymer is a polyaspartic acid crosslinked using a polyfunctional amine as a crosslinker or a salt thereof. The crosslinked polymer has a degree of crosslinking of 1.0 mol% or more and less than 2.2 mol%.SELECTED DRAWING: None

Description

The present invention relates to thickened compositions.

Carbomer is the most widely used cosmetic thickener on the market. Features of carbomer that are not found in other thickening agents include extremely high thickening properties and a refreshing feel when applied to the skin. Carbomer is a polyacrylic acid-based polymer.
Polyaspartic acid has a chemical structure similar to that of polyacrylic acid, can exhibit similar functions, and is biodegradable, so it is expected as an alternative material with less environmental load. Moreover, polyaspartic acid (salt) in which the chains are partially crosslinked by a polyvalent amine compound has been reported (Patent Document 1).

Japanese Patent Application Laid-Open No. 2002-179791

However, the thickening effect of crosslinked polyaspartic acid, which is being attempted as a thickening agent, is low and must be added in large amounts. Therefore, for example, in applications such as skin cosmetics, there is a problem of causing roughness and stickiness when applied to the skin.

The present invention has been made to solve the above problems, and by using a crosslinked polyaspartic acid or salt whose degree of crosslinking is controlled within a predetermined range, the thickening effect is enhanced even when blended in a small amount. An object of the present invention is to provide a thickening composition capable of

The content of the present disclosure includes the following embodiments [1] to [6].
[1] including a crosslinked polymer,
The crosslinked polymer is polyaspartic acid or a salt thereof crosslinked using a polyfunctional amine as a crosslinking agent,
A thickening composition, wherein the degree of cross-linking of the cross-linked polymer is 1.0 or more and less than 2.2 mol %.
[2] The thickening composition according to [1], wherein the polyfunctional amine is at least one selected from the group consisting of aliphatic diamines, alicyclic diamines and ether-based diamines.
[3] The thickening composition according to [1] or [2], wherein the polyaspartic acid salt is an organic base salt or an alkali metal salt.
[4] The thickening composition according to any one of [1] to [3], further containing water.
[5] The thickening composition according to [4], wherein the content of the crosslinked polymer is 0.05 to 10.0% by mass with respect to the total 100% by mass of the thickening composition.
[6] A cosmetic composition comprising the thickening composition according to any one of [1] to [5] and a cosmetic active ingredient.

ADVANTAGE OF THE INVENTION According to this invention, the thickening composition which can improve the thickening effect even if mix|blended in a small amount can be provided.

The present invention will now be described in more detail. In addition, this invention is not limited only to embodiment shown below.

"~" means greater than or equal to the value before the description of "~" and less than or equal to the value after the description of "~".

(Thickening composition)
The thickening composition of one embodiment of the present invention (hereinafter this embodiment) comprises a crosslinked polymer. The crosslinked polymer is polyaspartic acid or a salt thereof crosslinked using a polyfunctional amine as a crosslinking agent. The degree of cross-linking of the cross-linked polymer is 1.0 or more and less than 2.2 mol %.

[Crosslinked polymer]
The crosslinked polymer according to this embodiment is polyaspartic acid or a salt thereof crosslinked using a polyfunctional amine as a crosslinking agent. The crosslinked polymer according to this embodiment has a polyaspartic acid skeleton, and has a structure in which polyaspartic acid chains are linked to each other by polyfunctionality. The degree of cross-linking of the cross-linked polymer is 1.0 or more and less than 2.2 mol %.

Polyaspartic acid according to this embodiment is a polymer formed by peptide bonds of aspartic acid. Amide bonds in the main chain of polyaspartic acid may be α-bonds or β-bonds. Moreover, these binding modes may be the same or different for each structural unit. The amino group of aspartic acid and the carboxyl group at the α-position of aspartic acid are α-bonds, and the carboxyl group at the β-position of aspartic acid is β-bonding. The side chains of polyaspartic acid are represented by —CH ₂ —COOH (for α-bonds) or —COOH (for β-bonds). In the crosslinked polymer according to this embodiment, for example, when the polyfunctional amine is a diamine, a carboxyl group present in a side chain on one polyaspartic acid chain and a side chain on another polyaspartic acid chain The carboxyl group and the amino group of the diamine each form an amide bond, thereby cross-linking the polyaspartic acid chains.

In the crosslinked polymer according to this embodiment, some of the carboxyl groups on the side chains of polyaspartic acid form such crosslinks, and another part of the carboxyl groups on the side chains of polyaspartic acid ( The remainder may be the entirety) may be a free carboxylic acid or form a salt. The salt is not particularly limited, and examples thereof include alkali metal salts such as sodium salts and potassium salts, salts of organic bases such as triethylamine, N-methylmorpholine, triethanolamine and diisopropylethylamine. Specific examples of salts of polyaspartic acid include, for example, sodium salts of polyaspartic acid.

A carboxyl group of a side chain that does not form a bridge can be combined with -NH- in the amide bond of the main chain to form an imide ring. Therefore, an imide ring may be present in part of the main chain. That is, the main chain portion in some structural units in the polymer according to this embodiment may form part of the imide ring formed as described above. In this embodiment, "partially crosslinked" means that some of the carboxyl groups on the side chains of polyaspartic acid form crosslinks.

In addition, the weight-average molecular weight of individual polyaspartic acid chains interconnected by crosslinking in the polymer is preferably 40,000 or more, more preferably 80,000 or more, and even more preferably 100,000 or more. . The greater the weight average molecular weight of the polyaspartic acid chain, the greater the thickening effect. For example, when polysuccinimide is used as a raw material for producing polyaspartic acid as described later, these weight average molecular weights are those of polyaspartic acid obtained by hydrolyzing polysuccinimide used as a raw material. By measuring the salt by GPC, it can be obtained as a pullulan conversion value which is a standard substance.

[Method for producing crosslinked polymer]
The method for producing the crosslinked polymer according to the present embodiment is not particularly limited, but for example, after reacting polysuccinimide with a polyfunctional amine compound, the hydrolysis reaction of the reaction product is performed while adjusting the pH in an aqueous solution. Alternatively, it can be obtained by hydrolyzing while reacting polysuccinimide and polyfunctional amine in an aqueous solution. At this time, the imide ring may remain in some structural units.

[Polysuccinimide]
Although the method for producing polysuccinimide is not particularly limited, it can be produced, for example, by heating aspartic acid at 170 to 180° C. in vacuum in the presence of phosphoric acid for dehydration condensation. In order to obtain a polysuccinimide having a higher molecular weight, the polysuccinimide obtained as described above may be treated with a condensing agent such as dicyclohexylcarbodiimide. The weight-average molecular weight of the polysuccinimide is, for example, preferably 20,000 or more, more preferably 40,000 or more, and even more preferably 50,000 or more. The weight-average molecular weight in this case is a value converted using polymethyl methacrylate as a standard substance according to the GPC method.

[Polyfunctional amine]
Polyfunctional amines according to this embodiment are preferably amines having at least two primary and/or secondary amino groups.
Examples of diamine compounds include aliphatic diamines such as ethylenediamine and hexamethylenediamine, aliphatic diamines containing aromatic rings such as xylenediamine, alicyclic diamines such as norbornenediamine, and 1,2-bis(2-aminoethoxy). Ether-based diamines such as ethane, diethylene glycol bis(3-aminopropyl) ether, polyoxyethylenediamine, polyoxypropylenediamine, etc., amino acids and their derivatives having an amino group in the side chain represented by lysine, ornithine, cystine , cystamine, etc., in which monoamino compounds are linked by a disulfide bond, and derivatives thereof. Preferred among these are lysine, ornithine, cystine, cystamine and derivatives thereof, which are highly safe polymer degradation products. Derivatives include diketopiperazines, which are cyclic dimers of lysine and ornithine, and esters of lysine, ornithine, and cystine.

Examples of polyfunctional amine compounds other than diamine include tris(2-aminoethyl)amine, tris(3-aminopropyl)amine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

As a method of reacting polysuccinimide and a polyfunctional amine, for example, there is a method of carrying out in an organic solvent. An example in which the polyfunctional amine according to the present embodiment is a diamine will be described.
In the method of reacting polysuccinimide and diamine in an organic solvent, polysuccinimide is dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethylimidazolidinone (DMI), dimethylsulfoxide ( After dissolving in an aprotic polar organic solvent such as DMSO) or sulfolane, a diamine or a solution of the diamine in the organic solvent is added dropwise. At this time, the amount of the organic solvent used for dissolving the polysuccinimide is not particularly limited, but it is usually used at a polymer concentration of 1 to 50% by mass.

The temperature at which the polysuccinimide and the diamine are reacted is not particularly limited, but is, for example, room temperature to 80°C.

The conditions of the above reaction (reaction temperature, reaction time, reaction concentration, amount of diamine used, etc.) are not particularly limited, but the reaction between polysuccinimide and diamine is allowed to proceed even after the reaction has gelled to the extent that stirring becomes difficult. Therefore, it is better to maintain the reaction temperature.

For isolation of the crosslinked polysuccinimide produced by the reaction, known normal isolation procedures such as recrystallization, reprecipitation, filtration and concentration can be used.

After isolating the resulting crosslinked polysuccinimide, the imide ring of the isolated crosslinked polysuccinimide is hydrolyzed. In the hydrolysis, it is realized that the reaction system can be kept substantially stirred, the efficiency of hydrolysis of the imide ring is sufficient, the degree of hydrolysis of the amide bond in the main chain is small, and the pH can be controlled. If possible, the reaction conditions (reaction system, pH, temperature, polymer concentration, type of alkali, concentration of alkali, etc.) are not particularly limited.

The reaction system for hydrolysis of the crosslinked polysuccinimide is generally carried out by suspending the crosslinked polysuccinimide in an aqueous solution, but may contain various organic solvents that are miscible with water. Specific examples of various organic solvents miscible with water include alcohols such as methanol and ethanol, acetone, tetrahydrofuran, and the like. The pH at which the crosslinked polysuccinimide is hydrolyzed is generally preferably from 8.0 to 11.5, more preferably from 9.0 to 11.0. The higher the value, the higher the efficiency of hydrolysis of the imide ring, and the lower the value, the less the degree of hydrolysis of the undesirable backbone amide bond. As for the polymer concentration at the time of hydrolysis of crosslinked polysuccinimide, generally, the more water, the faster the reaction. However, when considering the productivity, the polymer concentration is preferably 0.5 to 10% by mass.

Specific examples of alkalis that can be used for hydrolysis of crosslinked polysuccinimide include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; A base can be mentioned.

The alkali used for hydrolyzing the crosslinked polysuccinimide is usually used in the form of an aqueous solution thereof, and its concentration is such that the efficiency of hydrolysis of the imide ring is sufficient and the degree of hydrolysis of the amide bond of the main chain is small. Although the concentration is not particularly limited as long as it can realize that the pH can be controlled, 5 to 48% is preferable, and 10 to 30% is more preferable. The higher the value, the higher the efficiency of hydrolysis of the imide ring, and the lower the value, the less the degree of hydrolysis of the undesirable backbone amide bond.

For the isolation of the crosslinked polymer of the present embodiment produced by the hydrolysis reaction of crosslinked polysuccinimide, known normal isolation procedures such as recrystallization, reprecipitation, filtration, and concentration can be used. can.

The size (average particle diameter) of the crosslinked polymer of this embodiment is not particularly limited, but is preferably 150 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less. By setting the average particle size to 150 μm or less, advantages such as excellent transparency of the thickened solution and smooth touch feeling can be obtained.

[Degree of cross-linking]
The amount of polyfunctional amine used in this embodiment may be appropriately selected according to the desired degree of cross-linking. For example, in the case of the example of the production method using the above-described diamine and polysuccinimide, from the viewpoint of imparting high water swellability to the finally produced crosslinked polymer according to the present embodiment, the amount of diamine used is polysuccinic acid It is 1.0 or more and less than 2.2 mol, preferably 1.0 to 2.0 mol, more preferably 1.2 to 1.8 mol, relative to 100 mol of imide in terms of moles, More preferably, it is 1.3 to 1.7 mol. When the amount of diamine used is 2 moles per 100 moles of polysuccinimide in terms of moles, it is simply defined as "the amount of diamine used is 2 mol %". When the amount of diamine used is in the range of 1.0 or more and less than 2.2 mol %, the thickening effect can be enhanced even if the thickening composition of the present embodiment is blended in a small amount. Here, the term "converted number of moles of polysuccinimide" means the number of moles of aspartic acid, which is the raw material used in the above-described method for synthesizing polysuccinimide.
The amount (mol %) of polyfunctional amine used relative to polysuccinimide refers to the "degree of cross-linking" in the present invention. "Mole %" is used as the unit of degree of cross-linking.

When the crosslinked polymer according to this embodiment is produced by a production method using diamine and polysuccinimide, the degree of crosslinking of the crosslinked polymer according to this embodiment is obtained from the degree of crosslinking of the crosslinked polysuccinimide before hydrolysis. The degree of crosslinking of the crosslinked polymer according to this embodiment is 1.0 or more and less than 2.2 mol%, preferably 1.0 to 2.0 mol%, more preferably 1.2 to 1.8 mol%. %, more preferably 1.3 to 1.7 mol %.

[water]
The thickening composition of this embodiment may not contain water. For example, the thickened composition of the present embodiment obtained by the method described later can be further subjected to a drying treatment or the like to obtain a powdery thickened composition. The thickening composition of this embodiment may consist only of a crosslinked polymer. That is, it may be substantially free of other components other than the crosslinked polymer according to the present embodiment. The meaning of "substantially free of other components" is, for example, that the content of the crosslinked polymer in the thickening composition is 95.0 to 100% by mass, and 98.0 to 100% by mass. It is preferably 99.0 to 100% by mass, and even more preferably 100%.

The thickening composition of this embodiment may contain water. For example, the thickened composition of the present embodiment obtained by the method described above may be used as it is without being subjected to dehydration treatment. Examples of the water of the present embodiment include ion-exchanged water.
Moreover, when the thickening composition contains water, the "thickening composition containing water" may be referred to as a "thickening solution".
The content of the crosslinked polymer is preferably 0.05 to 10.0% by mass, preferably 0.1 to 5.0%, based on the total 100% by mass of the thickening composition (thickening solution) containing water. % by mass is more preferable, 0.2 to 2.5% by mass is more preferable, and 0.2 to 1.5% by mass is particularly preferable.

When the thickening composition contains water, its pH value is preferably in the range of 5.0 to 10.0, more preferably in the range of 6.0 to 9.0.
A method for adjusting the pH value is not particularly limited, and a method using an acidic substance or a basic substance may be mentioned. Specific examples of acids include organic acids such as citric acid. Specific examples of bases include organic basic compounds such as ammonia and inorganic basic compounds such as sodium hydroxide.

[Other ingredients]
The thickening composition of this embodiment may further contain other components. Examples include cosmetic active ingredients. Additives often used in cosmetics, such as surfactants, stabilizers, and moisturizing agents, may also be used.

(Method for preparing thickening composition)
As a method for preparing the thickening composition of the present embodiment, for example, the crosslinked polymer according to the present embodiment described above is weighed in a predetermined amount, and if necessary, water or other components are added in a predetermined amount. A method of adding and stirring can be used.
When the thickening composition of the present embodiment contains water, an aqueous dispersion of the crosslinked polymer of the present embodiment may be prepared first and mixed with other components, if necessary.
If the thickening composition of this embodiment does not contain water, the solid crosslinked polymer may be weighed out in a predetermined amount and mixed with other solid ingredients, if desired. Alternatively, a dispersion containing a crosslinked polymer and water may be prepared in advance, and if necessary, mixed with other components to prepare a mixed solution, which may be dried before preparation.

(Cosmetic composition)
The cosmetic composition according to this embodiment contains the thickening composition and a cosmetic active ingredient. Cosmetic active ingredients include, for example, higher alcohols, lower alcohols, polyhydric alcohols, pH adjusters, surfactants, sequestering agents, antioxidants, physical and chemical sunscreens, vitamins, and skin protection. oils, hydrocarbon oils, moisturizers, antiperspirants, cleansers, fragrances, cosmetic colorants, antibacterial agents, bactericides, feel enhancers and foam stabilizers, other thickening agents, and the like. . The cosmetic composition according to this embodiment may further contain water.
When the cosmetic composition according to the present embodiment contains water, the content of the crosslinked polymer according to the present embodiment is 0.05 to 10.0% by mass with respect to the total 100% by mass of the cosmetic composition. is preferably 0.1 to 5.0% by mass, more preferably 0.2 to 2.5% by mass, particularly 0.2 to 1.5% by mass preferable.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
(material)
Aspartic acid: manufactured by YIXING QIANCHENG BIO-ENGINEERING, 99.97% purity Phosphoric acid: manufactured by Kanto Chemical Co., Ltd., 85% purity Dimethylformamide: manufactured by Kanto Chemical Co., Ltd., 99.5% purity Hexamethylenediamine (HAD): Kanto Chemical Co., Ltd. 98% purity diethylenetriamine (DTA): manufactured by Kanto Chemical Co., Ltd., 97% purity Tetraethylenepentamine (TEP): manufactured by Kanto Chemical Co., Ltd., 100% purity Ethylenediamine (EDA): manufactured by Kanto Chemical Co., Ltd., 99.0% purity methanol : manufactured by Kanto Chemical Co., Ltd., 99.8% purity Sodium hydroxide: manufactured by Kanto Chemical Co., Ltd., 48% purity

<Synthesis of polysuccinimide>
(Synthesis example 1)
160 parts of aspartic acid 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 6 hours. After pulverizing the reaction mixture, it was washed with distilled water until the filtrate became neutral, and vacuum-dried at 80°C to obtain 115 parts of polysuccinimide having a weight average molecular weight of 70,000.

<Measurement of weight average molecular weight of polysuccinimide>
The weight-average molecular weight of polysuccinimide was obtained as a polymethyl methacrylate conversion value by the GPC method (differential refractometer). G1000HHR column, G4000HHR column, and GMHHR-H column (TSKgel (registered trademark), Tosoh Corporation) were used for the measurement. Dimethylformamide containing 10 mM lithium bromide was used as the eluent.

<Synthesis of crosslinked polysuccinimide>
(Synthesis example 2)
10 parts of the polysuccinimide obtained in Synthesis Example 1 was mixed with 40 parts of dimethylformamide and dissolved by stirring at 60° C. for 5 hours. A mixed solution of 0.18 parts of hexamethylenediamine (HDA) and 1.6 parts of dimethylformamide was added dropwise while the solution was heated to 40°C, and the mixture was reacted for 8 hours while the temperature was maintained at 40°C. The resulting gel was added to 500 parts of deionized water and pulverized with a mixer. After filtration, the product was washed with 150 parts of methanol for 1 hour and vacuum-dried at 60° C. to obtain 10.1 parts of crosslinked polysuccinimide (PCI-1). The degree of cross-linking in this case is 1.5 mol %.

(Synthesis Example 3)
10.1 parts of crosslinked polysuccinimide (PCI-2) was obtained in the same manner as in Synthesis Example 2 except that 0.11 parts of diethylenetriamine (DTA) and 1.0 parts of dimethylformamide were used. The degree of cross-linking in this case is 1.0 mol %.

(Synthesis Example 4)
10.1 parts of crosslinked polysuccinimide (PCI-3) was obtained in the same manner as in Synthesis Example 2 except that 0.12 parts of tetraethylenepentamine (TEP) and 5.9 parts of dimethylformamide were used. The degree of cross-linking in this case is 1.5 mol %.

(Synthesis Example 5)
10.1 parts of crosslinked polysuccinimide (PCI-4) was obtained in the same manner as in Synthesis Example 2 except that 0.25 parts of ethylenediamine (EDA) and 2.3 parts of dimethylformamide were used. The degree of cross-linking in this case is 2.0 mol %.

(Comparative Synthesis Example 1)
10.2 parts of crosslinked polysuccinimide (cPCI-1) was obtained in the same manner as in Synthesis Example 2 except that 0.30 parts of hexamethylenediamine (HDA) and 2.7 parts of dimethylformamide were used. The degree of cross-linking in this case is 2.5 mol %.

(Comparative Synthesis Example 2)
10.2 parts of crosslinked polysuccinimide (cPCI-2) was obtained in the same manner as in Synthesis Example 2 except that 0.36 parts of hexamethylenediamine (HDA) and 3.23 parts of dimethylformamide were used. The degree of cross-linking in this case is 3.0 mol %.

(Comparative Synthesis Example 3)
10.2 parts of crosslinked polysuccinimide (cPCI-3) was obtained in the same manner as in Synthesis Example 2 except that 0.28 parts of diethylenetriamine (DTA) and 2.5 parts of dimethylformamide were used. The degree of cross-linking in this case is 2.5 mol %.

(Comparative Synthesis Example 4)
10.1 parts of crosslinked polysuccinimide (cPCI-4) was obtained in the same manner as in Synthesis Example 2 except that 0.2 parts of tetraethylenepentamine (TEP) and 9.8 parts of dimethylformamide were used. The degree of cross-linking in this case is 2.5 mol %.

(Comparative Synthesis Example 5)
10.2 parts of crosslinked polysuccinimide (cPCI-5) was obtained in the same manner as in Synthesis Example 2, except that 0.31 parts of ethylenediamine (EDA) and 2.9 parts of dimethylformamide were used. The degree of cross-linking in this case is 2.5 mol %.

<Synthesis of crosslinked sodium polyaspartate>
(Synthesis Example 6)
3.0 parts of the crosslinked polysuccinimide (PCI-1) obtained in Synthesis Example 2 was dispersed in 20 parts of methanol and 10 parts of deionized water. A mixed solution of 2.4 parts of 48% sodium hydroxide and 2.4 parts of methanol was divided into 10 portions, added every 30 minutes, and reacted for 15 hours. The reaction liquid was poured into 400 parts of methanol, and the precipitate was collected by filtration and washed with 100 parts of methanol. Vacuum dried at 60°C. The dried product was pulverized in a mortar, passed through a mesh of 20 to 40 μm using a stainless sieve (JIS Z-8801), and crosslinked sodium polyaspartate (PAN-1) 3 as the crosslinked polymer of the present invention. .0 copies were obtained.

(Synthesis Examples 7-9)
Crosslinked sodium polyaspartate (PAN-2) to (PAN-2) to ( PAN-4) 3.0 parts each.

(Comparative Synthesis Examples 6 to 10)
Comparative Examples Crosslinked sodium polyaspartate (cPAN-1) to (cPAN-5) 3.0 parts each.

<Preparation of thickening composition>
(Example 1)
After mixing 1.0 parts of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6 and 99.0 parts of ion-exchanged water, citric acid was added to adjust the pH to 7.0. A thickened composition containing water (thickened solution L1) of this example was obtained.

(Example 2)
The water of this example was prepared in the same manner as in Example 1, except that 0.6 parts of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6 and 99.4 parts of ion-exchanged water were used. A thickened composition containing (thickened solution L2) was obtained.

(Comparative example 1)
The same method as in Example 1 except that the crosslinked sodium polyaspartate (PAN-1) obtained in Comparative Synthesis Example 6 was used instead of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6. Thus, a thickened composition containing water (thickened solution cL1) of this comparative example was obtained.

(Comparative example 2)
The same method as in Example 2 except that the crosslinked sodium polyaspartate (PAN-1) obtained in Comparative Synthesis Example 6 was used instead of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6. Thus, a thickened composition containing water (thickened solution cL2) of this comparative example was obtained.

(Comparative Example 3)
The same method as in Example 1 except that the crosslinked sodium polyaspartate (cPAN-2) obtained in Comparative Synthesis Example 7 was used instead of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6. Thus, a thickened composition containing water (thickened solution cL3) of this comparative example was obtained.

(Comparative Example 4)
The same method as in Example 2 except that the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6 was replaced with the crosslinked sodium polyaspartate (cPAN-2) obtained in Comparative Synthesis Example 7. Thus, a thickened composition containing water (thickened solution cL4) of this comparative example was obtained.

(Example 3)
In place of 1.0 parts of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6 and 99.0 parts of ion-exchanged water, 0 of the crosslinked sodium polyaspartate (PAN-2) obtained in Synthesis Example 7 was used. A water-containing thickened composition (thickened solution L3) of this comparative example was obtained in the same manner as in Example 1, except that 0.6 parts and 99.4 parts of ion-exchanged water were used.

(Example 4)
In place of 1.0 parts of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6 and 99.0 parts of ion-exchanged water, 0 of the crosslinked sodium polyaspartate (PAN-3) obtained in Synthesis Example 8 was used. A water-containing thickened composition (thickened solution L4) of this comparative example was obtained in the same manner as in Example 1, except that 0.8 parts and 99.2 parts of ion-exchanged water were used.

(Example 5)
1.0 parts of the crosslinked sodium polyaspartate (PAN-1) obtained in Synthesis Example 6 and 99.0 parts of ion-exchanged water were replaced with 0 of the crosslinked sodium polyaspartate (PAN-4) obtained in Synthesis Example 9. A water-containing thickened composition (thickened solution L5) of this comparative example was obtained in the same manner as in Example 1, except that 0.6 parts and 99.4 parts of ion-exchanged water were used.

(Comparative Example 5)
The same method as in Example 3 except that the crosslinked sodium polyaspartate (cPAN-3) obtained in Comparative Synthesis Example 8 was used instead of the crosslinked sodium polyaspartate (PAN-2) obtained in Synthesis Example 7. Thus, a thickened composition containing water (thickened solution cL5) of this comparative example was obtained.

(Comparative Example 6)
The same method as in Example 4 except that the crosslinked sodium polyaspartate (cPAN-4) obtained in Comparative Synthesis Example 9 was used instead of the crosslinked sodium polyaspartate (PAN-3) obtained in Synthesis Example 8. Thus, a thickened composition containing water (thickened solution cL5) of this comparative example was obtained.

(Comparative Example 7)
The same method as in Example 5 except that the crosslinked sodium polyaspartate (PAN-4) obtained in Synthesis Example 9 was replaced with the crosslinked sodium polyaspartate (cPAN-5) obtained in Comparative Synthesis Example 10. Thus, a thickened composition containing water (thickened solution cL5) of this comparative example was obtained.

(Evaluation of thickening property)
Using a rotary rheometer MCR102, the initial viscosities (viscosities at a shear rate of 1/s) of the thickened solutions L1 to L5 and cL1 to cL7 obtained in Examples and the like were measured by the method described below. Table 1 shows the results.

<Viscosity measurement of thickened solution>
The viscosity of the thickened solution was measured using a rotary rheometer MCR102 (AntonPaar) under the conditions of cone plate CP-25, gap 0.106 mm, measurement temperature 25 ° C., shear rate 10 / s and pre-shear for 15 seconds. After standing for 30 seconds, the shear viscosity was measured at a shear rate of 1/s to 1000/s. A shear viscosity at a shear rate of 1/s was adopted as the initial viscosity.

"HDA", "DTA", "TEP" and "EDA" in Table 1 mean "hexamethylenediamine", "diethylenetriamine", "tetraethylenepentamine" and "ethylenediamine" respectively.

(Discussion)
As shown in Table 1, compared with Comparative Examples 1 to 7 in which the degree of crosslinking of the crosslinked polymer is 2.5 mol% and 3.0 mol%, the degree of crosslinking of the crosslinked polymer is 1.0 to 2.0 mol. %, a higher thickening effect was observed with a smaller amount.
When the degree of cross-linking of cross-linked polyaspartic acid and its salt is within a predetermined small range, the cross-linked polyaspartic acid and its salt swell greatly in ion-exchanged water, and the volume of the swollen cross-linked polymer in the thickened solution of the same concentration is reduced. It is presumed that the thickening effect is large because the ratio is large.

Claims (6)

comprising a crosslinked polymer;
The crosslinked polymer is polyaspartic acid or a salt thereof crosslinked using a polyfunctional amine as a crosslinking agent,
A thickening composition, wherein the degree of cross-linking of the cross-linked polymer is 1.0 or more and less than 2.2 mol %. The thickening composition according to Claim 1, wherein the polyfunctional amine is at least one selected from the group consisting of aliphatic diamines, alicyclic diamines and ether-based diamines. 3. The thickening composition according to claim 1 or 2, wherein the salt of polyaspartic acid is an organic base salt or an alkali metal salt. The thickening composition according to any one of claims 1 to 3, further comprising water. 5. The thickening composition according to claim 4, wherein the content of the crosslinked polymer is 0.05 to 10.0% by mass with respect to the total 100% by mass of the thickening composition. The thickening composition according to any one of claims 1 to 5,
a cosmetic active ingredient,
A cosmetic composition comprising: