Thickener

Abstract

The purpose of the present invention is to provide a thickener capable of increasing the viscosity of a composition while suppressing stickiness and maintaining a satisfactory use feel when applied to, for example, the skin, due to the thickener containing no polymer thickener or a decreased amount of a polymer thickener. The thickener of the present invention is characterized by containing a phospholipid and a biosurfactant and in that the ratio of the phospholipid is more than 4 parts by mass but not more than 10 parts by mass relative to 1 part by mass of the biosurfactant.

Description

[Technical field]

[0001] The present invention relates to a thickener that does not contain a polymeric thickener or has a reduced content of a polymeric thickener, and therefore is capable of increasing the viscosity of a composition while suppressing stickiness when applied to the skin, etc., and maintaining the feel of use. [Background technology]

[0002] In contrast to liquid preparations such as aqueous solutions and dispersions, if the viscosity of the topical preparation to be applied to the skin is increased, dripping during application is suppressed and the preparation is easier to apply. Therefore, a thickener that increases the viscosity is sometimes blended into topical preparations.

[0003] As thickeners, generally, polymers such as proteins such as gelatin, xanthan gum derived from microorganisms, carrageenan derived from seaweed, guar gum derived from plants, polysaccharides such as cellulose derivatives, etc. are used. However, polymeric thickeners can cause stickiness and deteriorate the feeling of use, especially when the topical agent is dried after application, such as when starch syrup is attached. Therefore, low molecular weight compounds or compositions having a thickening effect are desirable, but no practical low molecular weight thickeners have been developed so far.

[0004] For example, Patent Document 1 discloses a block copolymer containing a hydrophobic polymer unit and a sulfonic acid group-containing hydrophilic polymer unit as a relatively low molecular weight thickener component. However, the molecular weight of such a block copolymer is several tens of thousands or more, and it is not capable of solving the above-mentioned stickiness problem. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-241060 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, conventional thickeners are made of polymers such as proteins and polysaccharides, and therefore have the problem of stickiness. Therefore, an object of the present invention is to provide a thickener that does not contain a polymeric thickener or has a reduced content of a polymeric thickener, and thus can increase the viscosity of a composition while suppressing stickiness when applied to the skin, etc., and maintaining a good feel when used. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems, and as a result have found that by using phospholipids and a biosurfactant and appropriately specifying the ratio between them, entangled string-like molecular aggregates are formed, and a thickener can be obtained without using a polymeric thickener, thereby completing the present invention. The present invention will now be described.

[0008] [1] Contains phospholipids and biosurfactants. A thickening agent characterized in that the ratio of phospholipid to 1 part by mass of biosurfactant is more than 4 parts by mass and not more than 10 parts by mass. [2] The thickener according to [1] above, which contains a string-like molecular aggregate comprising the phospholipid and the biosurfactant. [3] The thickener according to [2] above, which contains 1 part by mass or more and 20 parts by mass or less of a polyhydric alcohol per 1 part by mass of the biosurfactant. [4] The thickening agent according to any one of [1] to [3] above, wherein the biosurfactant is a surfactin represented by the following formula (II) or a salt thereof: [ka] [In the formula, X represents an amino acid residue selected from leucine, isoleucine and valine, R 2 is C 9-18 indicates an alkyl group] [5] An external preparation comprising the thickener according to any one of [1] to [4] above. [6] The topical preparation according to the above [5], wherein the content of the polymer thickener is less than 1.0% by mass. [7] The topical preparation according to [5] or [6] above, which is a cosmetic preparation.

[0009] [8] Use of a thickening agent containing a phospholipid and a biosurfactant to increase the viscosity of a composition containing water, wherein the ratio of phospholipid to 1 part by weight of biosurfactant is more than 4 parts by weight and not more than 10 parts by weight. [9] The use according to [8] above, wherein the thickening agent contains a string-like molecular aggregate comprising the phospholipid and the biosurfactant.

[10] The use according to [8] or [9] above, wherein the thickener contains 1 part by mass or more and 20 parts by mass or less of a polyhydric alcohol per 1 part by mass of the biosurfactant.

[11] The use according to any one of the above [8] to

[10] , wherein the biosurfactant is a surfactin represented by the above formula (II) or a salt thereof.

[12] The use according to any one of [8] to

[11] above, wherein the concentration of the polymer thickener in the composition is less than 1.0 mass%.

[0010]

[13] A method for increasing the viscosity of a composition containing water, comprising: A method characterized by including a step of blending a thickening agent containing a phospholipid and a biosurfactant into the above composition, in which the ratio of phospholipid to 1 part by mass of biosurfactant is more than 4 parts by mass and not more than 10 parts by mass.

[14] The method according to

[13] , wherein the thickener contains a string-like molecular aggregate comprising the phospholipid and the biosurfactant.

[15] The method according to

[13] or

[14] above, wherein the thickener contains 1 part by mass or more and 20 parts by mass or less of a polyhydric alcohol per 1 part by mass of the biosurfactant.

[16] The method according to any one of

[13] to

[15] above, wherein the biosurfactant is a surfactin represented by the formula (II) above or a salt thereof.

[17] The method according to any one of the above

[13] to

[16] , wherein the concentration of the polymer thickener in the composition is less than 1.0 mass%. Effect of the Invention

[0011] The thickener according to the present invention can increase the viscosity of a composition even if no polymer thickener is used or the amount of the polymer thickener is reduced. As a result, when a composition containing the thickener according to the present invention is applied to the skin, the stickiness caused by the polymer thickener, especially after drying, is suppressed. Therefore, the thickener according to the present invention is very useful as a component for increasing the viscosity of external preparations such as cosmetics. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a photograph showing the appearance of the thickener according to the present invention. [Diagram 2] FIG. 2 is a graph showing the results of dynamic viscoelasticity measurement of the thickener according to the present invention. [Diagram 3] FIG. 3 is a photograph showing the results of magnified observation of the thickener according to the present invention using a freeze-fracture transmission electron microscope. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The thickener according to the present invention exhibits thickening properties even though it does not contain a polymer thickener or the content of the polymer thickener is less than 1.0% by mass.

[0014] In the present disclosure, the molecular weight of the polymer thickener is not particularly limited as long as the polymer thickener can be considered to be a polymer, and is, for example, 10,000 or more. Common polymer thickeners include, for example, cellulose-based polymer thickeners, which are cellulose and its derivatives; alginic acid-based polymer thickeners such as sodium alginate; starch-based polymer thickeners such as starch, carboxymethyl starch, and methylhydroxypropyl starch; other polysaccharide-based polymer thickeners such as agar, xanthan gum, carrageenan, and guar gum; protein-based polymer thickeners such as pectin, collagen, casein, albumin, and gelatin; vinyl-based polymer thickeners such as polyvinyl methyl ether and carboxyvinyl polymer; and acrylic-based polymer thickeners such as polyoxyethylene-based polymers, polyoxyethylene polyoxypropylene copolymer-based polymers, polyethyl acrylate, and polyacrylamide.

[0015] Phospholipids are a general term for lipids that have a phosphate moiety in their structure, and are classified into glycerophospholipids, which contain glycerin in their skeleton, and sphingophospholipids, which contain sphingosine in their skeleton. Sphingosine has a structure in which the hydroxyl group at the C2 position of glycerin is replaced with an amino group, and a long-chain alkyl group is further bonded to the C1 position. The phosphate group forms a phosphate ester with the hydroxyl group of glycerin or sphingosine. Since phospholipids are one of the components of cell membranes, gel compositions and emulsion compositions containing phospholipids have excellent usability.

[0016] The phospholipid may be one represented by the following general formula (III): [ka] [In the formula, R 3 and R 4 is independently 8-24 Alkyl group, C 8-24 Alkenyl group, or C 8-24 R represents an alkynyl group. 5 ~R 7 is independently C 1-6 represents an alkyl group.

[0017] C 8-24 An alkyl group refers to a linear or branched monovalent saturated aliphatic hydrocarbon group having from 8 to 24 carbon atoms. Examples include octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, eicosacilyl, docosyl, isotetradecyl, isohexadecyl, isooctadecyl, isoeicosacilyl, isodocosyl, 2-butyldecyl, 2-hexyldecyl, 2-octyldecyl, 2-decanyldecyl, 2-dodecanyldecyl, and tetracosyl.

[0018] C 8-24 The alkenyl group refers to a straight-chain or branched-chain monovalent unsaturated aliphatic hydrocarbon group having 8 to 24 carbon atoms and at least one carbon-carbon double bond.

[0019] C 8-24 An alkynyl group refers to a straight-chain or branched-chain monovalent unsaturated aliphatic hydrocarbon group having 8 to 24 carbon atoms and at least one carbon-carbon triple bond.

[0020] C 1-6 The alkyl group refers to a linear or branched monovalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms. Examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, and n-hexyl. 1-4 is an alkyl group, more preferably C 1-2 It is preferably an alkyl group, and even more preferably methyl.

[0021] A specific example of a phospholipid is lecithin, which is another name for phosphatidylcholine and has the following structure: [ka]

[0022] In addition, naturally derived lipid products containing phospholipids are sometimes called natural lecithin. For example, a phospholipid product derived from egg yolk is sometimes called egg yolk lecithin, and a phospholipid product derived from soybeans is sometimes called soybean lecithin.

[0023] Other examples of phospholipids include glycerophospholipids such as phosphatidic acid, bisphosphatidic acid, phosphatidylserine, phosphatidylethanolamine, phosphatidylmethylethanolamine, phosphatidylinositol, phosphatidylglycerol, and diphosphatidylglycerol; sphingophospholipids such as sphingosine, ceramide, sphingomyelin, and cerebroside; and hydrogenated lecithins such as hydrogenated soybean phospholipid and hydrogenated egg yolk lecithin.

[0024] Biosurfactants are natural surface-active compounds produced by microorganisms, and examples thereof include lipopeptide biosurfactants having a hydrophobic group and a hydrophilic peptide portion, particularly cyclic lipopeptide biosurfactants in which the lipopeptide portion is cyclic. The cyclic peptide portion contains one or more anionic groups, such as a carboxyl group or a phenolic hydroxyl group. Lipopeptide biosurfactants have the advantage of being easily decomposed by microorganisms and therefore having little impact on the environment.

[0025] The cyclic lipopeptide biosurfactant may be one or more selected from surfactin, arthrofactin, iturin, and salts thereof, with surfactin or a salt thereof being preferred.

[0026] Here, surfactin or a salt thereof refers to surfactin represented by general formula (II) or a salt thereof. [ka] [In the formula, R 2 and X have the same meaning as above.]

[0027] The amino acid residue represented by X may be either L- or D-form, but is preferably L-form. Examples of counter cations constituting a surfactin salt include alkali metal ions and quaternary ammonium ions. The alkali metal ions are not particularly limited, but include lithium ions, sodium ions, potassium ions, etc., with sodium ions being preferred. Examples of the substituents of the quaternary ammonium ions include C ions such as methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl. 1-6 Alkyl group; C with a substituent such as 2-hydroxyethyl 1-6 Examples of the organic groups include alkyl groups, aralkyl groups such as benzyl, methylbenzyl, and phenylethyl, and aryl groups such as phenyl, toluyl, and xylyl. Examples of the quaternary ammonium ion include tetramethylammonium ion, tetraethylammonium ion, and pyridinium ion.

[0028] "C 9-18 An "alkyl group" refers to a linear or branched monovalent saturated hydrocarbon group having 9 to 18 carbon atoms. Examples include n-nonyl, 6-methyloctyl, 7-methyloctyl, n-decyl, 8-methylnonyl, n-undecyl, 9-methyldecyl, n-dodecyl, 10-methylundecyl, n-tridecyl, 11-methyldodecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, and n-octadecyl.

[0029] Arthrofactin is represented by the general formula (IV). [ka]

[0030] Arthrofactin has one D-aspartic acid and one L-aspartic acid in its structure, and these amino acid residues may form salts. Examples of counter cations that constitute such salts include alkali metal ions and quaternary ammonium ions.

[0031] Iturin is represented by the general formula (V). [ka] In formula (V), R 8 is C 9-18 It represents an alkyl group, for example, -(CH 2 ) 10 CH 3 , -(CH 2 ) 8 CH(CH 3 )CH 2 CH 3 , -(CH 2 ) 9 CH(CH 3 ) 2 Shows.

[0032] One or more kinds of biosurfactants or their salts may be used. For example, a mixture of two or more kinds having different carbon numbers of hydrophobic groups may be used. The cyclic lipopeptide biosurfactant can be separated from the culture liquid by culturing a microorganism that produces the desired cyclic lipopeptide biosurfactant according to a known method, and can be used either as a purified product or as an unpurified product, for example, as the culture liquid. For example, a strain belonging to Bacillus subtilis can be mentioned as a microorganism that produces surfactin. Biosurfactants obtained by chemical synthesis can also be used in the same manner.

[0033] The phospholipid and the biosurfactant cooperate to form a string-like molecular assembly, and as a result, the thickener according to the present invention is considered to exhibit an excellent thickening effect, even though it does not contain a polymer thickener or contains a small amount of the polymer thickener. In the present disclosure, the string-like molecular assembly refers to an assembly formed from at least a phospholipid and a biosurfactant, and has a structure in which string-like assemblies are entangled. The width of the string-like molecular assembly can be, for example, 5 nm or more and 40 nm or less. Surfactants such as hexadecyltrimethylammonium bromide (CTAB) are also known to form string-like micelles, but the width of the string-like molecular assembly according to the present invention is several times larger than the width of the string-like micelles. Therefore, the string-like molecular assembly according to the present invention is considered to maintain an entangled structure even at a relatively low concentration, and to exhibit excellent thickening effect and thread-pulling properties.

[0034] The main solvent of the thickener according to the present invention is water, which may be water alone or a mixed solvent of a water-miscible organic solvent and water. A water-miscible organic solvent is an organic solvent that can be mixed with water without restrictions, and is preferably one that has little adverse effect on the human body, particularly human skin. Examples of water-miscible organic solvents include ethanol and isopropyl alcohol. When a water-miscible organic solvent is used, the ratio of the water-miscible organic solvent to the total of water and the water-miscible organic solvent is preferably 0.1% by mass or more and 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less or 5% by mass or less.

[0035] As described above, the thickener according to the present invention exhibits thickening properties even though it does not contain a polymer thickener or the amount of the polymer thickener is small. One aspect of the thickener according to the present invention that exhibits thickening properties while not containing a polymer thickener or the amount of the polymer thickener is small is to appropriately adjust the ratio of phospholipid to biosurfactant. Specifically, the ratio of phospholipid to 1 part by mass of biosurfactant can be more than 4 parts by mass and 10 parts by mass or less. If the ratio of phospholipid to biosurfactant is within this range, it is considered that a molecular aggregate similar to a polymer is more reliably formed and a thickening property similar to that of a polymer thickener is exhibited. The above ratio is preferably 4.5 parts by mass or more, and more preferably 8 parts by mass or less, and more preferably 6 parts by mass or less.

[0036] The thickener according to the present invention can be produced by a conventional method. For example, it may be produced by mixing at least phospholipid and biosurfactant in a solvent together with other components to be thickened, or the thickener according to the present invention may be added separately to the liquid composition to be thickened to thicken the liquid composition. In the latter embodiment, the thickener according to the present invention may or may not contain a solvent.

[0037] The thickener according to the present invention and the thickening composition containing the thickener according to the present invention may contain other components in addition to the above-mentioned phospholipid and biosurfactant, as well as the optional solvent. Examples of other components include polyhydric alcohols having three or more hydroxyl groups, such as glycerin. The amount of the polyhydric alcohol may be appropriately adjusted, and may be, for example, 1 part by mass or more and 20 parts by mass or less per part by mass of the biosurfactant. Polyhydric alcohols having three or more hydroxyl groups can be used as solvents at room temperature and normal pressure, and can also be used as moisturizers, water retaining agents, moisturizing agents, skin protective agents, oral hygiene agents, fragrances, etc. Examples of other components include ultraviolet absorbers, antioxidants, emollients, solubilizers, anti-inflammatory agents, moisturizers, preservatives, bactericides, pigments, fragrances, powders, etc.

[0038] The thickener according to the present invention and the thickening composition containing the thickener according to the present invention do not contain a polymer thickener or contain a small amount of the polymer thickener, so that they are less sticky after drying and have an excellent feeling of use. Specifically, the concentration of the polymer thickener in the thickener according to the present invention or the thickening composition containing the thickener according to the present invention is preferably less than 1.0% by mass. The concentration may be 0% by mass. Therefore, the thickening composition containing the thickener according to the present invention is particularly useful as an external preparation such as a cosmetic or skin external preparation that is applied directly to the skin.

[0039] Specifically, the thickener according to the present invention contains phospholipids, biosurfactant, and water, has a viscosity of 30 mPa·s or more and 600 Pa·s or less, and contains less than 1.0% by mass of polymeric thickener. The viscosity can be determined, for example, by rotating a cylinder or disk in a solution containing 0.1% by mass or more and 5% by mass or less of phospholipids, 0.2% by mass or more and 10% by mass or less of biosurfactant, water as a solvent, and containing no polymeric thickener or having a concentration of less than 1.0% by mass, measuring the viscous resistance torque acting on the cylinder or disk used, and converting the measured value. The viscous resistance torque can be measured by a conventional method. The viscosity is preferably 40 mPa·s or more, more preferably 50 mPa·s or more, and preferably 500 Pa·s or less.

[0040] This application claims the benefit of priority based on Japanese Patent Application No. 2020-8230, filed on January 22, 2020. The entire contents of the specification of Japanese Patent Application No. 2020-8230, filed on January 22, 2020, are incorporated by reference into this application. EXAMPLES

[0041] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and it is possible to carry out the present invention by making appropriate modifications within the scope of the above and below-mentioned aims, and all of these modifications are included in the technical scope of the present invention.

[0042] Example 1 Phospholipid ("L-α-dimyristoylphosphatidylcholine" NOF Corp., hereinafter abbreviated as "DMPC") (625 mg) was weighed into a test tube and dissolved by adding chloroform. Nitrogen gas was sprayed into the test tube while stirring the solution with a vortex mixer, and the chloroform was removed to form a lipid film on the wall of the test tube. After leaving it in a desiccator for 2 days, water or pH 7.4 phosphate buffer (5 mL) was added and hydrated at room temperature for 10 minutes. Then, by stirring with a vortex mixer for 3 minutes, a 200 mM DMPC liposome aqueous solution was prepared. The concentration of DMPC was measured using a phospholipid quantification kit ("Phospholipid C-Test Wako" Wako Pure Chemical Industries, Ltd.). Next, surfactin sodium (hereinafter abbreviated as "SFNa") (524 mg) was weighed into a test tube, and phosphate buffer (pH 7.4) (10 mL) or water was added to prepare a 50 mM SFNa aqueous solution. The above 200 mM DMPC liposome aqueous solution (2480 μL) and 50 mM SFNa aqueous solution (2000 μL) were mixed with 5520 μL of phosphate buffer (pH 7.4) or water so that the total concentration of DMPC and SFNa was 4 mass% or 8 mass%, and the mixture was stirred with a vortex mixer for 3 minutes and then stirred at 200 rpm overnight using a small thermostatic shaking incubator ("Bio Shaker BR-23FD" manufactured by Taitec Co., Ltd.). As a result, as shown in Figure 1, a viscous transparent composition was obtained, and it was found that when the DMPC content was high, a thickened gel-like composition was obtained that maintained the interface even when the test tube was tilted. In addition, similar results were obtained when, without preparing liposomes in advance, DMPC and SFNa powders were weighed into a test tube, water was added, and the mixture was stirred with a vortex mixer for 1 minute, and then stirred overnight in the same manner as above, although some of the powder remained undissolved. When the pH of these solutions was measured, it was found to be approximately pH 7.5, near neutral.

[0043] In addition, the dynamic viscoelasticity of a thickened gel composition in which the total ratio of DMPC and SFNa was 8% by mass was measured. The dynamic viscoelasticity was measured at 25°C using an Anton Paar modular compact rheometer 302 and a SANDBLASTED parallel plate with a diameter of 49.977 mm. The results are shown in Figure 2. Figure 2(a) shows the angular frequency dependence of the storage modulus (G') and loss modulus (G'') when the strain is fixed at 35%. As a result, it was found that the loss modulus (G") curve has a maximum value at the intersection with the storage modulus (G') curve, and that the storage modulus (G') curve becomes almost constant above each angular frequency at which the maximum is reached, indicating that this gel composition exhibits typical Maxwell fluid behavior. Figure 2(b) shows the Cole-Cole plot (G' vs G") of this gel-like composition. The data is distributed in a semicircular shape, which indicates that the composition behaves like a typical Maxwell fluid. This behavior differs from viscoelasticity due to the entanglement of polymer molecules, and suggests that the gel-like composition forms a string-like molecular assembly. The composition of the present invention that forms the string-like molecular aggregates exhibits viscosity in a static state, and exhibits the property of becoming more fluid when a force such as stirring is applied. The composition of the present invention having this string-like molecular aggregate structure has thixotropy, and when the composition is taken on the palm, the viscosity caused by the string-like molecular aggregate structure prevents dripping, and when the composition is applied to the skin, the string-like molecular aggregate structure collapses and the viscosity decreases, making application easy. In addition, after application, the string-like molecular aggregate structure is restored again, so the composition exhibits excellent usability characteristics in that dripping from the application site is unlikely to occur. Conventional topical preparations in which a thickened moisturizing preparation is applied directly to the skin have problems such as a decrease in viscosity due to salt on the skin, and stickiness when a large amount of a polymeric thickener such as polysaccharide is blended to maintain viscosity. By applying the composition forming the string-like molecular assembly of the present invention, a topical preparation that maintains viscosity, is not sticky, and has a good feel when used can be provided.

[0044] Example 2 A gel composition was prepared in the same manner as in Example 1, except that the concentration of SFNa was 10 mM and the concentration of DMPC was 50 mM. The obtained gel composition was quickly frozen and the surface was fractured under high vacuum conditions. Next, the solvent on the fractured surface was etched to expose the object to be observed, and then a replica film was made of platinum and carbon on the surface, and observed with a freeze-fracture transmission electron microscope (FF-TEM, "JEM-1010" manufactured by JEOL Ltd.). The results are shown in FIG. 3. As shown in Figure 3, string-like entangled molecular assemblies were observed in the gel composition with a DMPC:SFNa = 5:1 (mass ratio), and the average string width at 20 randomly selected points was 20.4 ± 3.7 nm. This width is several times larger than the string-like micelles formed by ordinary surfactants such as CTAB, so it is believed that the flat nanoparticles formed by DMPC and SFNa were stacked on top of each other to form string-like molecular assemblies. The reason why the thickener according to the present invention exhibits thickening properties even without containing a polymer is believed to be due to such a molecular assembly structure.

Claims

1. Contains phospholipids, biosurfactants and polyhydric alcohols. The biosurfactant is a surfactin represented by the following formula (II) or a salt thereof: 【Chemistry 1】 [In the formula, X represents an amino acid residue selected from leucine, isoleucine and valine; R 2 represents a C 9-18 alkyl group. The ratio of phospholipid to 1 part by mass of biosurfactant is more than 4 parts by mass and 10 parts by mass or less; A thickening agent, characterized in that the ratio of polyhydric alcohol to 1 part by mass of biosurfactant is 1 part by mass or more and 20 parts by mass or less.

2. The thickening agent according to claim 1 , which contains a string-like molecular aggregate comprising the phospholipid and the biosurfactant.

3. A thickener described in claim 1 or 2, which does not contain a polymeric thickener or contains less than 1.0 mass% of a polymeric thickener.

4. A thickening agent described in any one of claims 1 to 3, wherein the phospholipid is a glycerophospholipid or a sphingophospholipid.

5. An external preparation comprising the thickener according to any one of claims 1 to 4.

6. The external preparation according to claim 5, which is a cosmetic preparation.

7. 1. A method for increasing the viscosity of a composition comprising water, comprising: The method is characterized by comprising a step of blending a thickening agent into the above composition, the thickening agent containing a phospholipid, a biosurfactant and a polyhydric alcohol, wherein the biosurfactant is a surfactin represented by the following formula (II) or a salt thereof, the ratio of the phospholipid to 1 part by mass of the biosurfactant is more than 4 parts by mass and not more than 10 parts by mass, and the ratio of the polyhydric alcohol to 1 part by mass of the biosurfactant is 1 part by mass or more and 20 parts by mass or less. 【Chemistry 2】 [In the formula, X represents an amino acid residue selected from leucine, isoleucine and valine; R 2 represents a C 9-18 alkyl group.

8. The method according to claim 7, wherein the thickening agent comprises a worm-like molecular assembly comprising the phospholipid and the biosurfactant.

9. The method described in claim 7 or 8, wherein the phospholipid is a glycerophospholipid or a sphingophospholipid.

10. The method according to any one of claims 7 to 9, wherein the concentration of the polymeric thickener in the composition is less than 1.0% by weight.

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