Method for producing emulsion composition

Abstract

To provide a technique for producing an emulsion composition free from separation of an oil phase and an aqueous phase by using a polymeric emulsifier.SOLUTION: An emulsion composition production method is provided, including a step of emulsifying, under heating, a water-soluble copolymer having at least one constitutional unit (a) induced from a specific hydrophobic monomer and at least one constitutional unit (b) induced from a hydrophilic monomer as essential constitutional units, an oil phase component, and an aqueous phase component.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for producing an emulsion composition under heating. [Background technology]

[0002] Cosmetics based on emulsion compositions such as emulsions are widely used because they can combine the effects of both oil phase components and aqueous phase components. Conventionally, low molecular weight emulsifiers (low molecular weight surfactants) such as polyoxyethylene hydrogenated castor oil have been used as emulsifiers, but in recent years, polymeric emulsifiers such as PEMULEN (registered trademark) (Lubrizol Corporation) have been increasingly used, and are attracting attention as they can reduce the amount of conventional low molecular weight emulsifiers used.

[0003] PEMULEN is an (acrylates / alkyl acrylate (C10-30)) crosspolymer that is characterized by its ability to emulsify any type of oil. Patent Document 1 discloses a polymer emulsifier having a branched polysiloxane side chain with a low degree of polymerization, and discloses a technology for producing an oil-in-water emulsion composition containing polysiloxane as an oil phase component, in which the average particle size of the polysiloxane is fine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-174486 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, a process for producing a highly stable emulsion composition generally involves heating a mixture of aqueous phase components (aqueous phase) and a mixture of oil phase components (oil phase) separately, and then adding the oil phase while heating and stirring the aqueous phase. By carrying out emulsification while heating, the components of each phase are uniformly dissolved and dispersed, and a highly stable emulsion composition can be prepared.

[0006] However, many conventional polymeric emulsifiers do not exhibit sufficient emulsifying ability when used alone under heat, and so they have generally been used in combination with conventional low-molecular-weight surfactants such as polyoxyethylene hydrogenated castor oil.

[0007] In view of the above-mentioned problems, an object of the present invention is to provide a technique for producing an emulsion composition using a polymer emulsifier without separation of the oil phase and the spray phase. [Means for solving the problem]

[0008] The present invention, which solves the above-mentioned problems, provides a method for producing an emulsion composition, which includes an emulsification step of emulsifying, under heating, a water-soluble copolymer having, as essential constituent units, one or more constituent units (a) derived from a hydrophobic monomer represented by the following general formula (I), (II), or (III), and one or more constituent units (b) derived from a hydrophilic monomer, together with an oil phase component and an aqueous phase component: General formula (I) [ka] (I)

[0009] (R in general formula (I) 1 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 2 represents a branched hydrocarbon group having 13 to 30 carbon atoms and not containing a ring structure, or a hydrocarbon group having 6 to 12 carbon atoms and not containing a ring structure and having two or more branches.

[0010] General formula (II) [ka] (II)

[0011] (R in general formula (II) 3 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R4 ,R 5 may be the same or different and represent a branched acyl group containing no ring structure and having 6 to 22 carbon atoms. X represents a group in which an OH group has been eliminated from a trihydric alcohol.

[0012] General formula (III) [ka] (III)

[0013] (R in general formula (III) 6 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 7 ,R 8 ,R 9 may be the same or different and represent a branched acyl group containing no ring structure and having 6 to 22 carbon atoms. Y represents a group in which an OH group has been eliminated from a tetrahydric alcohol.

[0014] In the present invention, by using the water-soluble copolymer as an emulsifier, it is possible to prepare an emulsion composition that does not separate into an oil phase and an aqueous phase upon heating.

[0015] In a preferred embodiment of the present invention, the emulsification step is a step of emulsifying the water-soluble copolymer, the oil phase component, and the aqueous phase component by stirring under heating.

[0016] In a preferred embodiment of the present invention, the temperature in the emulsification step is greater than 40°C. According to the present invention, a stable emulsion composition can be prepared by emulsifying with heating.

[0017] In a preferred embodiment of the present invention, the emulsification step does not substantially contain any emulsifier other than the water-soluble copolymer. In the present invention, a stable emulsion composition can be prepared by emulsifying the water-soluble copolymer alone under heating.

[0018] In a preferred embodiment of the present invention, the aqueous phase components include a component having a melting point of more than 40°C and / or a component that is not soluble or dispersible in the aqueous phase at 40°C or lower. In a preferred embodiment of the present invention, the oil phase components include a component having a melting point of more than 40°C and / or a component that is not soluble or dispersible in the oil phase at 40°C or lower. According to the present invention, by carrying out emulsification under heating, a stable emulsion composition can be prepared even if it contains components that are difficult to dissolve or disperse or components with high melting points.

[0019] In a preferred embodiment of the present invention, the hydrophilic monomer is one or more hydrophilic monomers selected from the group consisting of polymerizable carboxylic acids, hydrophilic monomers represented by the following general formula (IV), hydrophilic monomers represented by the following general formula (V), hydrophilic monomers represented by the following general formula (VI), and hydrophilic monomers represented by the following general formula (VII). General formula (IV) [ka] (IV)

[0020] (R in general formula (IV) 10 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 11 represents an alkylene group having 2 to 4 carbon atoms which may have a hydroxyl group, and R 12 represents a hydrogen atom, an aromatic hydrocarbon group having 6 to 10 carbon atoms, an aliphatic hydrocarbon group having 1 to 14 carbon atoms, or an acyl group having 1 to 12 carbon atoms. n represents an integer of 6 to 40.

[0021] General formula (VI) [ka] (VI)

[0022] (R in general formula (VI) 15 represents a hydrogen atom or a methyl group.)

[0023] General formula (VII) [ka] (VII)

[0024] (R in general formula (VII) 16 represents a hydrogen atom or a methyl group, and GO- represents a group obtained by removing a hydrogen atom from the hydroxyl group at position 1 of a reducing sugar. m represents 2 or 3, and l represents an integer from 1 to 5.

[0025] General formula (VIII) [ka] (VIII)

[0026] (R in general formula (VIII) 17 represents a hydrogen atom or a methyl group, R 18 represents an amino acid residue, a polyamine residue, or an amino alcohol residue. Q represents an oxygen atom or a group represented by NH.

[0027] In a preferred embodiment of the present invention, the hydrophobic monomer is a hydrophobic monomer represented by the general formula (II), and the water-soluble monomer is a hydrophilic monomer represented by the general formula (IV).

[0028] In a preferred embodiment of the present invention, the emulsion composition is an external preparation for skin.

[0029] The present invention also relates to an emulsion composition produced by the above-mentioned production method. The emulsion composition of the present invention is a good one that does not exhibit separation between the oil phase and the aqueous phase.

[0030] In a preferred embodiment of the present invention, the emulsion composition contains, as an aqueous phase component, a component having a melting point of more than 40°C and / or a component that is not soluble or dispersible in the aqueous phase at 40°C or lower, and contains, as an oil phase component, a component having a melting point of more than 40°C and / or a component that is not soluble or dispersible in the oil phase at 40°C or lower.

[0031] The present invention provides a method for designing an emulsion composition that is emulsified under heating, comprising the steps of: The method includes the steps of: selecting, as the aqueous phase component, a component having a melting point of greater than 40°C and / or a component that does not dissolve or disperse in the aqueous phase at temperatures greater than 40°C; selecting, as the oil phase component, a component having a melting point of greater than 40°C and / or a component that does not dissolve or disperse in the oil phase at temperatures greater than 40°C; and selecting, as the emulsifier, a water-soluble copolymer having, as essential structural units, one or more structural units (a) derived from a hydrophobic monomer represented by general formula (I), (II), or (III) above, and one or more structural units (b) derived from a hydrophilic monomer. [Effects of the Invention]

[0032] According to the present invention, by using the water-soluble copolymer as an emulsifier, a stable emulsion composition can be prepared by emulsification under heating. [Brief explanation of the drawings]

[0033] [Figure 1] 1 shows a photograph taken from the side of a composition after stirring using squalane as the oil agent and (a) a POE surfactant, (b) an AAMA polymer, and (c) a water-soluble copolymer as the emulsifier. [Figure 2] 1 shows a photograph of the liquid surface of a composition using squalane as the oil agent and (a) a POE surfactant, (b) an AAMA polymer, and (c) a water-soluble copolymer as the emulsifiers after stirring. In the photograph, the black arrow indicates the separated oil agent. [Figure 3] 1 shows a microscope image of emulsion droplets in an emulsion composition of a water-soluble copolymer, squalane, and water. [Figure 4] These are evaluations of the surface condition and microscopic images of emulsion compositions prepared with or without heating using a water-soluble copolymer or AAMA polymer as an emulsifier, immediately after preparation, after one week of storage, and after one month of storage (20°C). DETAILED DESCRIPTION OF THE INVENTION

[0034] The present invention is characterized by the use of a water-soluble copolymer having a structural unit (a) derived from a hydrophobic monomer and a structural unit (b) derived from a hydrophilic monomer. <1> In the section 2. above, hydrophobic monomers, hydrophilic monomers, and copolymers thereof, which are water-soluble copolymers, will be explained.

[0035] <1> Water-soluble copolymer (1) Hydrophobic Monomer In the present invention, a water-soluble copolymer is used that contains, as an essential structural unit, one or more structural units derived from a hydrophobic monomer represented by the general formula (I), (II), or (III) (hereinafter, sometimes simply referred to as "structural unit I"). In the present invention, the term "structural unit derived from a monomer" refers to a structural unit formed by cleavage of the carbon-carbon unsaturated bond of the corresponding monomer through a polymerization reaction. The hydrophobic monomers represented by formula (I), (II) or (III) will be described below.

[0036] (1-1) Hydrophobic monomer represented by general formula (I) In the general formula (I), R 1 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 2 represents a branched hydrocarbon group having 13 to 30 carbon atoms and not containing a ring structure, or a hydrocarbon group having 6 to 12 carbon atoms and not containing a ring structure and having two or more branches. where R 1 Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a cyclopropyl group. 1 is preferably a hydrogen atom or a methyl group.

[0037] Also, R 2Examples of the branched hydrocarbon group having 13 to 30 carbon atoms and not containing a ring structure, represented by the formula (I), include a 1-methyldodecanyl group, an 11-methyldodecanyl group, a 3-ethylundecanyl group, a 3-ethyl-4,5,6-trimethyloctyl group, a 1-methyltridecanyl group, a 1-hexyloctyl group, a 2-butyldecanyl group, a 2-hexyloctyl group, a 4-ethyl-1-isobutyloctyl group, a 1-methylpentadecanyl group, a 2-hexyldecanyl group, a 2-octyldodecanyl group, a 2-hexyldodecanyl group, a 16-methylheptadecanyl group, a 9-methylheptadecanyl group, a 7-methyl-2-(3-methylhexyl)decanyl group, a 3,7,11,15-tetra-methylhexadecanyl group, a 2-octyldodecanyl group, a 2-decyltetradecanyl group, and a 2-dodecylhexadecanyl group.

[0038] Also, R 2Examples of hydrocarbon groups having 6 to 12 carbon atoms, not containing a ring structure, and having two or more branches, include 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl group, 1,3-dimethylbutyl group, 1,2,2-trimethylpropyl group, 1,1-dimethylpentanyl group, 1-isopropylbutyl group, 1-isopropyl-2-methylpropyl group, 1,1-diethylpropyl group, 1-ethyl-1-isopropylpropyl group, 2-ethyl-4-methylpentyl group, 1-propyl-2,2-dimethylpropyl group, 1,1,2-trimethylpentyl group, 1-isopropyl-3-methylbutyl group, 1,2-dimethyl-1-ethylbutyl group, 1,3-dimethyl-1-ethylbutyl group, 1-ethyl-1-isopropylpropyl group, 1,1-diethylpentanyl group, Examples include a methylhexyl group, a 1-methyl-1-ethylpentyl group, a 1-methyl-1-propylbutyl group, a 1,4-dimethylhexyl group, a 1-ethyl-3-methylpentyl group, a 1,5-dimethylhexyl group, a 1-ethyl-6-methylheptyl group, a 1,1,3,3-tetramethylbutyl group, a 1,2-dimethyl-1-isopropylpropyl group, a 3-methyl-1-(2,2-dimethylethyl)butyl group, a 1-isopropylhexyl group, a 3,5,5-trimethylhexyl group, a 2-isopropyl-5-methylhexyl group, a 1,5-dimethyl-1-ethylhexyl group, a 3,7-dimethyloctyl group, a 2,4,5-trimethylheptyl group, a 2,4,6-trimethylheptyl group, and a 3,5-dimethyl-1-(2,2-dimethylethyl)hexyl group.

[0039] (1-2) Hydrophobic monomers represented by general formula (II) or (III) In the general formulas (II) and (III), R 3 , R 6 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 4 ,R 5 , R 7 , R 8 , R 9 may be the same or different and represent a branched acyl group containing no ring structure and having 6 to 22 carbon atoms. X represents a group in which an OH group has been eliminated from a trihydric alcohol.

[0040] Here, examples of the alkyl group represented by R3 and R6 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a cyclopropyl group, etc. In the present invention, R3 is preferably a hydrogen atom or a methyl group.

[0041] Furthermore, examples of branched acyl groups having 6 to 22 carbon atoms and not containing a ring structure represented by R4, R5, R7, R8, and R9 include a 2-methylpentanoyl group, a 3-methylpentanoyl group, a 4-methylpentanoyl group, a 2-ethylbutanoyl group, a 2-ethylbutanoyl group, a 2,2-dimethylbutanoyl group, a 3,3-dimethylbutanoyl group, a 2-methylhexanoyl group, a 4-methylhexanoyl group, a 5-methylhexanoyl group, a 2,2-dimethylpentanoyl group, a 4,4-dimethylpentanoyl group, a 2-methylheptanoyl group, and a 2-ethylhexanoyl group. Silyl group, 2-propylpentanoyl group, 2,2-dimethylhexanoyl group, 2,2,3-trimethylpentanoyl group, 2-methyloctanoyl group, 3,3,5-trimethylhexanoyl group, 2-methylnonanoyl group, 4-methylnonanoyl group, 8-methylnonanoyl group, 4-ethyloctanoyl group, 2-ethyloctanoyl group, 2-butylhexanoyl group, 2-tert-butylhexanoyl group, 2,2-diethylhexanoyl group, 2,2-dimethyloctanoyl group, 3,7-dimethyloctanoyl group, neodecanoyl group, 7-methyl Dodecanoyl group, 2-methyl-2-ethyloctanoyl group, 2-methylundecanoyl group, 10-methylundecanoyl group, 2,2dimethyldecanoyl group, 2-ethyldecanoyl group, 2-butyloctanoyl group, diethyloctanoyl group, 2-tert-butyl-2,2,4-trimethylpentanoyl group, 10-methyldodecanoyl group, 3-methyldodecanoyl group, 4-methyldodecanoyl group, 11-methyldodecanoyl group, 10-ethylundecanoyl group, 12-methyltridecanoyl group, 2-butyldecanoyl group, 2-hexyl group Examples include an octanoyl group, a 2-butyl-2-ethyloctanoyl group, a 12-methyltetradecanoyl group, a 14-methylpentadecanoyl group, a 2-butyldodecanoyl group, a 2-hexyldecanoyl group, a 16-methylheptadecanoyl group, a 2,2-dimethylhexanoyl group, a 2-butylhexadecanoyl group, a 2-hexyldodecanoyl group, a 2,4,10,14-tetramethylpentanoyl group, an 18-methylnonadecanoyl group, a 3,7,11,15-tetramethylhexadecanoyl group, and a 19-methyleicosanoyl group.

[0042] In a preferred embodiment of the present invention, in general formulas (II) and (III), R4, R5, R7, R8, and R9 may be the same or different and are a branched, C10-22 acyl group not containing a ring structure, or a C6-9 acyl group not containing a ring structure and having two or more branches.

[0043] In a preferred embodiment, examples of the branched acyl group having 10 to 22 carbon atoms and not containing a ring structure, represented by R4, R5, R7, R8, and R9, include a 2-methylnonanoyl group, a 4-methylnonanoyl group, an 8-methylnonanoyl group, a 4-ethyloctanoyl group, a 2-ethyloctanoyl group, a 2-butylhexanoyl group, a 2-tert-butylhexanoyl group, a 2,2-diethylhexanoyl group, a 2,2-dimethyloctanoyl group, a 3,7-dimethyloctanoyl group, a neodecanoyl group, a 7-methyldecanoyl group, a 2-methyl-2-ethyloctanoyl group, a 2-methylundecanoyl group, a 10-methylundecanoyl group, a 2,2-dimethyldecanoyl group, a 2-ethyldecanoyl group, a 2-butyloctanoyl group, a diethyloctanoyl group, a 2-tert-butyl-2,2,4-trimethyl ... trimethylpentanoyl group, 10-methyldodecanoyl group, 3-methyldodecanoyl group, 4-methyldodecanoyl group, 11-methyldodecanoyl group, 10-ethylundecanoyl group, 12-methyltridecanoyl group, 2-butyldecanoyl group, 2-hexyloctanoyl group, 2-butyl-2-ethyloctanoyl group, 12-methyltetradecanoyl group, 14-methylpentadecanoyl group, 2-butyl Examples include tildodecanoyl group, 2-hexyldecanoyl group, 16-methylheptadecanoyl group, 2,2-dimethylhexanoyl group, 2-butylhexadecanoyl group, 2-hexyldodecanoyl group, 2,4,10,14-tetramethylpentanoyl group, 18-methylnonadecanoyl group, 3,7,11,15-tetramethylhexadecanoyl group, and 19-methyleicosanoyl group.

[0044] In addition, examples of the acyl group having 6 to 9 carbon atoms and no ring structure, represented by R4, R5, R7, R8, and R9 in a preferred embodiment include a 2,2-dimethylbutanoyl group, a 3,3-dimethylbutanoyl group, a 2,2-dimethylpentanoyl group, a 4,4-dimethylpentanoyl group, a 2,2-dimethylhexanoyl group, a 2,2,3-trimethylpentanoyl group, and a 3,5,5-trimethylhexanoyl group.

[0045] The group derived from a trihydric alcohol, represented by X in general formula (II), is not particularly limited as long as it is a group in which an OH group has been separated from a trihydric alcohol, and a suitable example is a group in which an OH group has been separated from a trihydric alcohol selected from the group consisting of glycerin, trimethylolpropane, and trimethylolethane.

[0046] Furthermore, the group derived from a tetrahydric alcohol, represented by Y in general formula (III), is not particularly limited as long as it is a group in which an OH group has been separated from a tetrahydric alcohol, and a suitable example is a group in which an OH group has been separated from a tetrahydric alcohol selected from the group consisting of diglycerin, pentaerythritol, erythritol, D-threitol, and L-threitol.

[0047] In the present invention, it is particularly preferable to use a water-soluble copolymer containing the structural unit II. In a more preferred embodiment of the present invention, the hydrophobic monomer represented by general formula (II) is a hydrophobic monomer represented by the following general formula (V).

[0048] General formula (V) [ka] (V) (In general formula (V), R13 and R14 may be the same or different and represent a branched, ring-free acyl group having 16 to 22 carbon atoms. Z represents a group in which an OH group has been eliminated from a trihydric alcohol.)

[0049] R in general formula (V)13 , R 14 The acyl group has 12 to 22 carbon atoms, more preferably 14 to 20 carbon atoms, and even more preferably 16 to 20 carbon atoms. In addition, R in general formula (V) 13 , R 14 The main chain of the acyl group preferably has 9 to 21 carbon atoms, more preferably 12 to 20 carbon atoms, and even more preferably 16 to 18 carbon atoms. In addition, R in general formula (V) 13 , R 14 The number of branches in the acyl group is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Furthermore, R in general formula (V) 13 , R 14 In the acyl group, the higher the carbon atom number in the main chain to which the branched chain is bonded, the more preferable it is. Specifically, the branched chain is preferably bonded to the first to third carbon atoms, more preferably the first or second carbon atoms, and even more preferably the first carbon atom, from the carbon atom at the end of the main chain.

[0050] R 13 , R 14 Specific preferred examples of the alkyl group include a 10-methylundecanoyl group, a 10-methyldodecanoyl group, an 11-methyldodecanoyl group, a 10-ethylundecanoyl group, a 12-methyltridecanoyl group, a 12-methyltetradecanoyl group, a 14-methylpentadecanoyl group, a 16-methylheptadecanoyl group, a 2,4,10,14-tetramethylpentanoyl group, an 18-methylnonadecanoyl group, a 3,7,11,15-tetramethylhexadecanoyl group, and a 19-methyleicosanoyl group.

[0051] The group derived from a trihydric alcohol, represented by Z in general formula (V), is not particularly limited as long as it is a group in which an OH group has been separated from a trihydric alcohol, and a suitable example is a group in which an OH group has been separated from a trihydric alcohol selected from the group consisting of glycerin, trimethylolpropane, and trimethylolethane.

[0052] (2) Hydrophilic Monomer As the hydrophilic monomer in the present invention, polymerizable carboxylic acids and compounds represented by the above general formula (IV), the following general formula (VI), the following general formula (VII) and the following general formula (VIII) can be used.

[0053] (2-1) Polymerizable Carboxylic Acid In the present invention, specific examples of polymerizable carboxylic acids or salts thereof include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, and their sodium salts, potassium salts, ammonium salts, and amine salts. Among these, acrylic acid, methacrylic acid, and their salts are particularly preferred due to their high polymerizability. When introducing a structural unit derived from a polymerizable carboxylic acid salt into the water-soluble copolymer of the present invention, the polymerizable carboxylic acid may be converted into a salt in advance and then subjected to a polymerization reaction, or the structural unit derived from the polymerizable carboxylic acid may be introduced into the water-soluble copolymer by polymerization, and then the resulting copolymer may be neutralized with a base to convert into a salt.

[0054] (2-2) Hydrophilic monomer represented by general formula (IV) In the general formula (IV), R 10 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and R 11 represents an alkylene group having 2 to 4 carbon atoms which may have a hydroxyl group, and R 12 represents a hydrogen atom, an aromatic hydrocarbon group having 6 to 10 carbon atoms, an aliphatic hydrocarbon group having 1 to 14 carbon atoms, or an acyl group having 1 to 12 carbon atoms. n represents an integer of 6 to 40.

[0055] In the general formula (IV), R 10 Examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a cyclopropyl group. 10 is preferably a hydrogen atom or a methyl group.

[0056] Also, R 11Examples of the alkylene group represented by the formula (I) include an ethylene group, a propylene group, an isopropylene group, a 2-hydroxypropylene group, a 1-hydroxy-2-methylethylene group, and a 2-hydroxy-1-methylethylene group. Of these, an ethylene group or a propylene group is preferred, and an ethylene group is more preferred.

[0057] Also, R 12 Among the groups represented by the formula (I), examples of aromatic groups having 6 to 10 carbon atoms include phenyl, benzyl, methylphenyl, and ethylphenyl; examples of aliphatic hydrocarbon groups having 1 to 14 carbon atoms include methyl, ethyl, butyl, tertiary butyl, hexyl, cyclohexyl, octyl, 2-ethylhexyl, and lauryl; and examples of acyl groups having 1 to 12 carbon atoms include formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, and lauroyl. Of these, the group represented by R5 is preferably an aliphatic hydrocarbon group having 1 to 14 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms.

[0058] Furthermore, n in the general formula (IV) is a numerical value ranging from 6 to 40.

[0059] Among the monomers represented by the general formula (IV), R 11 Specific examples of monomers in which n is a propylene group include polypropylene glycol (9) monoacrylate, polypropylene glycol (13) monoacrylate, polypropylene glycol (9) monomethacrylate, and polypropylene glycol (13) monomethacrylate. The number in parentheses represents n. Many of these polymers are commercially available. Specific examples of these commercially available products include products under the trade name "Blemmer" AP-400, AP-550, AP-800, PP-500, and PP-800 (all manufactured by NOF Corporation).

[0060] Among the monomers represented by the general formula (IV), R 11Specific examples of the monomer in which is an ethylene group include polyethylene glycol (10) monoacrylate, polyethylene glycol (8) monomethacrylate, polyethylene glycol (23) monoacrylate, polyethylene glycol (23) monomethacrylate, methoxypolyethylene glycol (9) acrylate, methoxypolyethylene glycol (9) methacrylate, methoxypolyethylene glycol (23) methacrylate, oleyloxypolyethylene glycol (18) methacrylate, lauroxypolyethylene glycol (18) acrylate, lauroyloxypolyethylene glycol (10) methacrylate, and stearoxypolyethylene glycol (30) monomethacrylate.

[0061] The above-mentioned hydrophilic monomers can be obtained in high yields by esterification of the corresponding polyethylene glycol, polyethylene glycol monoether, or polyethylene glycol monoester with the chloride or anhydride of acrylic acid or methacrylic acid. Many commercially available products are also available, and these can be used. Specific examples of such commercially available products include those under the trade names Blemmer, AE-400, PE-350, AME-400, PME-400, PME-1000, ALE-800, and PSE-1300 (all manufactured by NOF Corporation).

[0062] (2-3) Hydrophilic monomer represented by general formula (VI) As the hydrophilic monomer in the present invention, a hydrophilic monomer represented by the following general formula (VI) may be used.

[0063] (General formula VI) [ka] (VI) (R in general formula (VI) 15 represents a hydrogen atom or a methyl group.)

[0064] Specific examples of the hydrophilic monomer represented by the general formula (VI) include 2-acryloyloxyethyl phosphorylcholine (APC) and 2-methacryloyloxyethyl phosphorylcholine (MPC). These monomers can be synthesized, for example, by the following method described in Polymer Journal, Vol. 22, No. 5.

[0065] <Synthesis method> 2-Bromoethylphosphoryl dichloride is reacted with 2-hydroxyethyl methacrylate or 2-hydroxyethyl acrylate to obtain 2-methacryloyloxyethyl-2'-bromoethyl phosphate or 2-acryloyloxyethyl-2'-bromoethyl phosphate, and then these compounds are reacted with triethylamine in methanol.

[0066] (2-4) Hydrophilic monomer represented by general formula (VII) As the hydrophilic monomer in the present invention, a hydrophilic monomer represented by the following general formula (VII) may be used.

[0067] General formula (VII) [ka] (VII) (R in general formula (VII) 16 represents a hydrogen atom or a methyl group, and GO- represents a group obtained by removing a hydrogen atom from the hydroxyl group at position 1 of a reducing sugar. m represents 2 or 3, and l represents an integer from 1 to 5.

[0068] In the hydrophilic monomer represented by general formula (VII), the reducing sugar represented by GO-, which is formed by removing a hydrogen atom from the 1-hydroxyl group, can be one or more selected from the group consisting of monosaccharides such as glucose, mannose, galactose, arabinose, xylose, and ribose, disaccharides such as maltose, lactose, and cellobiose, trisaccharides such as maltotriose, and oligosaccharides such as maltooligosaccharides. Of these, one or more selected from the group consisting of glucose, galactose, arabinose, xylose, ribose, maltose, lactose, and cellobiose are preferred, with glucose being particularly preferred. Furthermore, glucosyloxyethyl methacrylate (hereinafter abbreviated as GEMA) or glucosyloxyethyl acrylate (hereinafter abbreviated as GEA) is preferred as the monomer represented by general formula (VII).

[0069] (2-5) Hydrophilic monomer represented by general formula (VIII) As the hydrophilic monomer in the present invention, a hydrophilic monomer represented by the following general formula (VIII) may be used.

[0070] General formula (VIII) [ka] (VIII) (R in general formula (VIII) 17 represents a hydrogen atom or a methyl group, R 18 represents an amino acid residue, a polyamine residue, or an amino alcohol residue. Q represents an oxygen atom or a group represented by NH.

[0071] In the monomer of general formula (VIII), R 18 The amino acid of the amino acid residue represented by is not particularly limited as long as it is a commonly known amino acid, and specific examples include glycine, alanine, glutamine, lysine, arginine, etc. Among these, lysine residue is particularly preferred because the resulting water-soluble copolymer has an excellent effect of restoring the skin barrier.

[0072] Also, R18 In the polyamine residue represented by the formula (I), the polyamine refers to an amine having two or more amino groups, each of which may be substituted with an alkyl group, in the same molecule, and specific examples include diamines, triamines, tetraamines, and amines in which the hydrogen atoms of these amino groups are substituted with alkyl groups. Among these, diamines are preferred because the resulting topical skin preparation containing the water-soluble copolymer has a particularly excellent feel when used, and particularly preferred examples include ethylenediamine, 1,4-diamino-n-butane, 1,6-diamino-n-hexane, etc., because the raw materials for synthesis are easily available.

[0073] Furthermore, R 18 The amino alcohol in the amino alcohol residue represented by the formula (I) means a compound having an amino group, which may be substituted with an alkyl group, and an alcoholic hydroxyl group in the same molecule. The amino alcohol is not particularly limited as long as it is a commonly known one, and specific examples include ethanolamine, triethylaminoethanol, etc.

[0074] The salt of the monomer represented by general formula (VIII) is not particularly limited, but specific examples include sodium salts, potassium salts, ammonium salts, amine salts, etc., in which the acid moiety is neutralized with a base, and hydrochlorides, sulfates, nitrates, phosphates, citrates, oxalates, carbonates, etc., in which the amino group moiety is neutralized with an acid. When introducing a structural unit derived from a salt of the monomer represented by general formula (VIII) into the water-soluble copolymer of the present invention, the monomer represented by general formula (VIII) may be previously converted into a salt and then subjected to a polymerization reaction, or the structural unit derived from the monomer represented by general formula (VIII) may be introduced into the water-soluble copolymer by polymerization, and then neutralized to form a salt.

[0075] Suitable specific examples of the monomer represented by formula (VIII) and salts thereof include compounds having the following structures and salts thereof.

[0076] [ka]

[0077]

change

[0078]

change

[0079]

change

[0080]

change

[0081]

change

[0082]

change

[0083]

change

[0084]

change

[0085]

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[0086]

change

[0087] The hydrophilic monomer represented by general formula (VIII) can be synthesized, for example, by an esterification reaction or an amidation reaction using (meth)acrylic acid or (meth)acrylic acid chloride as shown below.

[0088] [ka] [ka] (R in the reaction formula 17 represents a hydrogen atom or a methyl group, R 18 represents an amino acid residue, a polyamine residue, or an amino alcohol residue. Q represents an oxygen atom or a group represented by NH.

[0089] As described above, in the present invention, the hydrophilic polymers that can be used are those represented by the general formula (IV), the general formula (VI), the general formula (VII), and the general formula (VIII). In a preferred embodiment of the present invention, the water-soluble copolymer comprises a constitutional unit IV derived from the general formula (IV) above.

[0090] (3) Water-soluble copolymer In the present invention, a water-soluble copolymer having structural units II and IV can be preferably used, and a water-soluble copolymer having structural units V and IV is more preferably used. Among these water-soluble copolymers, it is particularly preferable to use (methoxy PEG-23 methacrylate / glyceryl methacrylate diisostearate) copolymer. By containing such a water-soluble copolymer, an emulsion composition can be obtained which is low in irritation, less sticky, and has excellent emulsion stability.

[0091] The (methoxy PEG-23 methacrylate / glyceryl methacrylate diisostearate) copolymer contains, as the structural unit (a), a hydrophobic monomer represented by the general formula (V), R 13 , R 14The copolymer mainly contains structural units (a) derived from a hydrophobic monomer in which the aryl group is a 16-methylheptadecanoyl group. Furthermore, as the structural unit (b), among the hydrophilic monomers represented by the general formula (IV), R 10 is a methyl group, R 11 is an ethylene group, R 12 The copolymer mainly contains structural units (b) derived from a hydrophilic monomer in which n is a methyl group and n is 23.

[0092] Generally, highly hydrophobic surfactants are suitable for forming water-in-oil emulsion compositions, while highly hydrophilic surfactants are suitable for forming oil-in-water emulsion compositions.Similarly, in the case of the water-soluble copolymer of the present invention, when the proportion of the hydrophobic structural unit (a) is high, it is suitable for forming water-in-oil emulsion compositions, and when the proportion of the hydrophilic structural unit (b) is high, it is suitable for forming oil-in-water emulsion compositions. In this way, by appropriately adjusting the proportions and ratios of the structural units (a) and (b), it is possible to adjust the emulsion form of the emulsion composition to be formed.

[0093] In the present invention, the proportion of the structural unit (a) in all structural units in the water-soluble copolymer is preferably from 1 to 50 mass %, more preferably from 20 to 50 mass %, and even more preferably from 30 to 40 mass %. By setting the proportion of the structural unit (a) in the water-soluble copolymer within the above range, it is possible to provide an oil-in-water emulsion composition with reduced stickiness.

[0094] In the present invention, the proportion of the structural unit (b) in all structural units in the water-soluble copolymer is preferably from 50 to 99 mass %, more preferably from 50 to 80 mass %, and even more preferably from 60 to 70 mass %. By setting the proportion of the structural unit (b) in the water-soluble copolymer within the above range, it is possible to provide an oil-in-water emulsion composition with reduced stickiness.

[0095] In the present invention, the mass ratio of the structural unit (a) to the structural unit (b) constituting the water-soluble copolymer is preferably 10:90 to 50:50, more preferably 20:80 to 50:50, and even more preferably 30:70 to 40:60.

[0096] Furthermore, the molar ratio of the structural unit (a) to the structural unit (b) constituting the water-soluble copolymer is preferably 15:85 to 62:38, more preferably 29:71 to 62:38, and even more preferably 41:59 to 52:48. By setting the mass ratio and molar ratio of the structural unit (a) and the structural unit (b) in the water-soluble copolymer within the above ranges, it is possible to obtain a water-soluble copolymer with excellent emulsifying power that is suitable for forming an oil-in-water emulsion composition.

[0097] In the present invention, the average molecular weight of the water-soluble copolymer is preferably 20,000 to 110,000, more preferably 20,000 to 80,000, more preferably 30,000 to 80,000, more preferably 40,000 to 70,000, even more preferably 50,000 to 70,000, and still more preferably 57,000 to 66,000. The average molecular weight herein refers to the weight average molecular weight measured by GPC and converted into polystyrene.

[0098] <2> Method for producing emulsion composition The present invention includes an emulsification step of emulsifying the above-mentioned water-soluble copolymer, an oil phase component, and an aqueous phase component under heating. The temperature in the emulsification step is preferably above 40°C, more preferably 50°C or higher, even more preferably 60°C or higher, and particularly preferably 65°C or higher. The temperature in the emulsification step is preferably 90°C or lower, more preferably 85°C or lower, and even more preferably 80°C or lower. In the present invention, a stable emulsion composition can be prepared by using the water-soluble copolymer as an emulsifier and carrying out emulsification under heating.

[0099] In the emulsification step, a preferred example is a mode in which an aqueous phase component containing the water-soluble copolymer and an oil phase component are separately prepared and then mixed by stirring. More specifically, a preferred embodiment involves preparing an aqueous solution in which the water-soluble copolymer is dispersed, mixing this with other aqueous phase components, and stirring and mixing the mixture of aqueous phase components with a mixture of oil phase components prepared in advance. The step of preparing the aqueous solution in which the water-soluble copolymer is dispersed is preferably carried out under heating. The step of mixing the aqueous solution in which the water-soluble copolymer is dispersed with other aqueous phase components is preferably carried out under heating. The step of preparing a mixture of oil phase components is preferably carried out under heating.

[0100] The amount of the water-soluble copolymer added in the emulsification step is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by mass, based on the total amount of the emulsion composition to be produced. By adjusting the amount of the water-soluble copolymer to be added within the above range, the emulsion stability of the emulsion composition can be further improved.

[0101] In the emulsification step, the blending ratio of the aqueous phase component and the oil phase component to be emulsified can be appropriately adjusted by changing the ratio of the structural unit (a) and the structural unit (b) in the water-soluble copolymer. Hereinafter, the contents of the oil phase and the aqueous phase when a water-soluble copolymer containing the structural unit (a) and the structural unit (b) in a ratio suitable for forming the above-mentioned oil-in-water emulsion composition is used will be described. In the present specification, the oil phase and oil phase components, and the water phase and water phase components are explained as not including the water-soluble copolymer of the present invention.

[0102] The amount of oil phase component added in the emulsification step is preferably 0.01 to 80% by mass, more preferably 0.1 to 70% by mass, based on the total amount of the emulsion composition to be produced. By adjusting the amount of the oil phase component to be added within the above range, the emulsion stability of the emulsion composition can be improved. The oil phase components are oily and lipophilic components, and refer to components contained in the oil phase of the emulsion composition.

[0103] In the emulsification step, the mixing mass ratio of the water-soluble copolymer to the oil phase component is preferably 1:100 to 1:0.2, more preferably 1:70 to 1:0.3. By setting the mass ratio of the water-soluble copolymer to the oil phase component within the above range, the emulsion stability of the emulsion composition can be improved.

[0104] The mixing mass ratio of the oil phase to the aqueous phase in the emulsification step is preferably 0.1:99.9 to 80:20, more preferably 1:99 to 65:35. By setting the mass ratio of the oil phase to the water phase within the above range, a stable oil-in-water emulsion composition can be formed.

[0105] The components contained in the oil phase and the water phase are not particularly limited. Examples of oils constituting the oil phase include liquid oils, solid oils, waxes, hydrocarbon oils, higher fatty acids, higher alcohols, synthetic ester oils, and silicone oils.

[0106] Examples of liquid oils and fats include avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, camellia oil, castor oil, linseed oil, safflower oil, cottonseed oil, perilla oil, meadowfoam oil, soybean oil, peanut oil, tea seed oil, Japanese kaya oil, rice bran oil, Chinese tung oil, Japanese tung oil, jojoba oil, germ oil, triglycerin, glycerin trioctanoate, and glycerin triisopalmitate.

[0107] Examples of solid fats and oils include cacao butter, coconut oil, horse fat, hardened coconut oil, palm oil, beef tallow, mutton tallow, hardened beef tallow, palm kernel oil, lard, beef bone fat, Japan wax kernel oil, hardened oil, beef foot fat, Japan wax, and hardened castor oil.

[0108] Examples of waxes include beeswax, candelilla wax, cotton wax, carnauba wax, bayberry wax, Ibota wax, whale wax, montan wax, rice bran wax, lanolin, kapok wax, acetated lanolin, liquid lanolin, sugarcane wax, lanolin fatty acid isopropyl, hexyl laurate, reduced lanolin, jojoba wax, hard lanolin, shellac wax, POE lanolin alcohol ether, POE lanolin alcohol acetate, POE cholesterol ether, lanolin fatty acid polyethylene glycol, and POE hydrogenated lanolin alcohol ether.

[0109] Examples of hydrocarbon oils include liquid paraffin, ozokerite, pristane, paraffin, ceresin, squalene, petrolatum, and microcrystalline wax.

[0110] Examples of higher fatty acids include lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, 12-hydroxystearic acid, undecylenic acid, and tall acid.

[0111] Examples of higher alcohols include cetyl alcohol, stearyl alcohol, behenyl alcohol, batyl alcohol, myristyl alcohol, and cetostearyl alcohol.

[0112] Synthetic ester oils include isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, isocetyl stearate, isocetyl isostearate, sucrose stearate, sucrose oleate, cholesteryl 12-hydroxystearate, ethylene glycol di-2-ethylhexylate, dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glycerin di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexylate, trimethylolpropane triisostearate, and pentane tetra-2-ethylhexylate. Erythritol, glycerin tri-2-ethylhexanoate, trimethylolpropane triisostearate, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, glycerin trimyristate, tri-2-heptylundecanoic acid glyceride, castor oil fatty acid methyl ester, oleic acid oil, cetostearyl alcohol, acetoglyceride, 2-heptylundecyl palmitate, cetyl palmitate, adipyl diisobutyl phosphate, N-lauroyl-L-glutamic acid-2-octyldodecyl ester, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, 2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, triethyl citrate, and the like.

[0113] Examples of silicone oils include chain polysiloxanes such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane, and cyclic polysiloxanes such as decamethylpolysiloxane, dodecamethylpolysiloxane, and tetramethyltetrahydrogenpolysiloxane.

[0114] One or more types of oils can be used.

[0115] The aqueous phase components preferably contain a component having a melting point of more than 40°C or a component that is not soluble or dispersible in the aqueous phase at 40°C or below. The oil phase component preferably contains a component having a melting point of over 40°C or a component that is not soluble or dispersible in the oil phase at 40°C or below. The term "dissolved" as used herein includes compatibility. As the component that is not soluble or dispersible in the water phase or oil phase at 40°C or lower, a component that is soluble or dispersible in the water phase or oil phase at a temperature above 40°C is preferred. The component having a melting point of more than 40°C may be a component having a melting point of 50°C or higher, or may be a component having a melting point of 60°C or higher. The melting point of the component having a melting point of more than 40°C is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. A component that does not dissolve or disperse in the aqueous phase or oil phase at 40°C or below is preferably a component that dissolves or disperses in the aqueous phase or oil phase at 100°C or below, more preferably 90°C or below, and even more preferably 80°C or below. Examples of such oil phase components include waxes, higher alcohols, fatty acids, petrolatum, hardened rapeseed oil, ester oil, crosslinked methylpolysiloxane, and highly polymerized silicone.

[0116] The emulsification step may be performed in a form in which substantially no emulsifier other than the water-soluble copolymer is added. Here, "substantially no emulsifiers other than the water-soluble copolymers" means that the amount of emulsifiers other than the water-soluble copolymers added is 0.3% by mass or less, preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0.001% by mass or less, based on the total amount of the emulsion composition to be produced. It is particularly preferred that no emulsifiers other than the water-soluble copolymers are added. The water-soluble copolymer used in the present invention has sufficient emulsifying ability by itself under heating.

[0117] In the emulsification step, optional additive components that are usually added to cosmetics may be added. Examples of such additive components include humectants such as polyethylene glycol, glycerin, 1,3-butylene glycol, erythritol, sorbitol, xylitol, and maltitol; lower alcohols such as ethanol; antioxidants such as butylhydroxytoluene, tocopherol, and phytin; antibacterial agents such as benzoic acid, salicylic acid, sorbic acid, parahydroxybenzoic acid alkyl esters, and hexachlorophene; benzoic acid-based ultraviolet absorbers such as paraaminobenzoic acid (hereinafter abbreviated as "PABA"), PABA monoglycerin ester, N,N-dipropoxy PABA ethyl ester, N,N-diethoxy PABA ethyl ester, N,N-dimethyl PABA methyl ester, N,N-dimethyl PABA ethyl ester, N,N-dimethyl PABA butyl ester, and N,N-dimethyl PABA 2-ethylhexyl ester; anthranilic acid-based ultraviolet absorbers such as homomenthyl-N-acetylanthranilate; amyl salicylate, menthyl salicylate, and the like. salicylic acid-based ultraviolet absorbers such as salicylate, homomenthyl salicylate, octyl salicylate, phenyl salicylate, benzyl salicylate, and p-isopropanol phenyl salicylate; octyl cinnamate, ethyl 4-isopropyl cinnamate, methyl 2,5-diisopropyl cinnamate, ethyl 2,4-diisopropyl cinnamate, methyl 2,4-diisopropyl cinnamate, propyl p-methoxycinnamate, and isopropyl p-methoxycinnamate. Cinnamic acid-based ultraviolet absorbers such as cinnamate, isoamyl-p-methoxycinnamate, octyl-p-methoxycinnamate (2-ethylhexyl-p-methoxycinnamate), 2-ethoxyethyl-p-methoxycinnamate, cyclohexyl-p-methoxycinnamate, ethyl-α-cyano-β-phenylcinnamate, 2-ethylhexyl-α-cyano-β-phenylcinnamate, and glyceryl mono-2-ethylhexanoyl-di-para-methoxycinnamate;[3-bis(trimethylsiloxy)methylsilyl-1-methylpropyl]-3,4,5-trimethoxycinnamate, [3-bis(trimethylsiloxy)methylsilyl-3-methylpropyl]-3,4,5-trimethoxycinnamate, [3-bis(trimethylsiloxy)methylsilylpropyl]-3,4,5-trimethoxycinnamate, [3-bis(trimethylsiloxy)methylsilylbutyl]-3,4,5-trimethoxycinnamate, [3-tris(trimethylsiloxy)silylbutyl]-3,4,5-trimethoxycinnamate, Silicone cinnamic acid ultraviolet absorbers such as [3-tris(trimethylsiloxy)silylbutyl]-3,4,5-trimethoxycinnamate and [3-tris(trimethylsiloxy)silyl-1-methylpropyl]-3,4-dimethoxycinnamate; 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, Benzophenone-based ultraviolet absorbers such as 4'-methylbenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 4-phenylbenzophenone, 2-ethylhexyl-4'-phenyl-benzophenone-2-carboxylate, 2-hydroxy-4-n-octoxybenzophenone, and 4-hydroxy-3-carboxybenzophenone; 3-(4'-methylbenzylidene)-d,l-camphor, 3-benzylidene-d,l-camphor, urocanic acid ethyl ester, 2-phenyl-5-methylbenzoxazole, 2 UV absorbers such as 2'-hydroxy-5-methylphenylbenzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, dibenzalazine, dianisoylmethane, 4-methoxy-4'-t-butyldibenzoylmethane, 5-(3,3'dimethyl-2-norbornylidene)-3-pentan-2-one; organic acids such as acyl sarcosinates (e.g., sodium lauroyl sarcosinate), glutathione, citric acid, malic acid, tartaric acid, and lactic acid;Vitamin A and its derivatives, vitamin B6 hydrochloride, vitamin B6 tripalmitate, vitamin B6 dioctanoate, vitamin B2 and its derivatives, vitamin B12, vitamin B15 and its derivatives, vitamin E such as α-tocopherol, β-tocopherol, γ-tocopherol, vitamin E acetate, vitamin D, vitamin H, pantothenic acid, pantethine, nicotinamide, benzyl nicotinate, vitamins such as γ-oryzanol, allantoin, glycyrrhizic acid (salt), glycyrrhetinic acid and its derivatives, trane tranexamic acid and its derivatives (examples of tranexamic acid derivatives include dimers of tranexamic acid (e.g., trans-4-(trans-aminomethylcyclohexanecarbonyl)aminomethylcyclohexanecarboxylic acid hydrochloride, etc.), esters of tranexamic acid and hydroquinone (e.g., trans-4-aminomethylcyclohexanecarboxylic acid 4'-hydroxyphenyl ester, etc.), esters of tranexamic acid and gentisic acid (e.g., 2-(trans-4-aminomethylcyclohexylcarbonyloxy)-5-hydroxybenzoic acid and its salts, etc.), Amides of tranexamic acid (e.g., trans-4-aminomethylcyclohexanecarboxylic acid methylamide and its salts, trans-4-(P-methoxybenzoyl)aminomethylcyclohexanecarboxylic acid and its salts, trans-4-guanidinomethylcyclohexanecarboxylic acid and its salts, etc.), hinokitiol, bisabolol, eucalptone, thymol, inositol, saponins such as saikosaponin, carrot saponin, loofah saponin, and soapberry saponin, pantothenyl ethyl ether, ethinyl estradiol, tranexamic acid, Various agents such as arbutin, cepharanthine, placenta extract, etc.; extracts of plants such as dock, sophora flavescens, water hyacinth, orange, sage, yarrow, mallow, swertia japonica, thyme, angelica, spruce, birch, horsetail, loofah, horse chestnut, saxifrage, arnica, lily, mugwort, peony, aloe, gardenia, and jasmine; pigments; porous and / or water-absorbent powders (e.g., starches obtained from corn, potato, etc., powders of silicic anhydride, talc, kaolin, magnesium aluminum silicate, calcium alginate, etc.); neutralizers; preservatives; fragrances;Pigments, etc.;

[0118] The present invention can be applied to methods for producing cosmetics such as emulsions, creams, beauty serums, sunscreens, and liquid foundations, external skin preparations, quasi-drugs, and pharmaceuticals. In particular, in view of the increasing need for preparing homemade cosmetics, the present invention is preferably applied to the production of cosmetics.

[0119] The emulsification step is preferably a step of emulsifying by stirring. The stirring method in the emulsification step is not particularly limited, and a general machine such as a homogenizer can be used. On the other hand, the emulsification step of the present invention can be carried out using a household mixer. Here, the term "household mixer" refers to a mixer sold as a household appliance, rather than a mixer with a strong mixing force used in the industrial production of emulsion compositions.

[0120] The stirring method of the household mixer is not particularly limited, but a preferred example is one in which emulsification is carried out based on shear force generated by rotating rotor blades.

[0121] Preferred examples of household mixers include equipment used as household cooking utensils, and preferred examples include lightweight mixers weighing preferably 10 kg or less, more preferably 8 kg or less, even more preferably 6 kg or less, even more preferably 4 kg or less, and even more preferably 2 kg or less. Specifically, examples include hand blenders, handheld milk frothers, tabletop mixers, tabletop food processors, and electric whisks. These household mixers have poorer mixing power than industrially used emulsifying devices. However, in the method for producing an emulsion composition of the present invention, by using the water-soluble copolymer described above as an emulsifier, it is possible to prepare an emulsion composition without separation of the oil phase and the aqueous phase even using such a household mixer with poor mixing power. In other words, the emulsion composition can be prepared with less energy.

[0122] Furthermore, the stirring force used when the water-soluble copolymer, oil phase component, and aqueous phase component are stirred and emulsified in the emulsification step preferably satisfies the condition defined in Definition A below.

[0123] [Definition A] When 2 parts by mass of a polyoxyethylene ester ether type nonionic surfactant or 0.3 parts by mass of an acrylic acid / methacrylic acid copolymer as an emulsifier, 12 parts by mass of a solution containing 1,3-butylene glycol and glycerin in a 1:1 ratio, and the remainder of the water are mixed at room temperature to prepare an aqueous solution, and then 65 parts by mass of an oil selected from Group A below are stirred at room temperature to prepare 100 parts by mass of an emulsion composition, the stirring force is insufficient to disperse all of the oil as emulsified droplets. (A) Squalane, mineral oil, isostearic acid, oleic acid, linoleic acid, linolenic acid, caprylic / capric triglyceride, triethylhexanoin, olive fruit oil, polydimethylsiloxane, cyclopentasiloxane (However, if a polyoxyethylene ester ether type nonionic surfactant is selected as the emulsifier, mineral oil, triethylhexanoin, and olive fruit oil cannot be selected from Group A.)

[0124] In the present invention, even when emulsification is carried out by stirring with a weak stirring force as defined in Definition A, an emulsion composition without phase separation can be produced.

[0125] A specific example of the "polyoxyethylene ester ether type nonionic surfactant" in Definition A is polyoxyethylene hydrogenated castor oil.

[0126] Furthermore, the "acrylic acid-methacrylic acid copolymer" in Definition A specifically includes (acrylates / alkyl acrylate (C10-30)) crosspolymer.

[0127] Furthermore, the volume of the mixture of emulsifier, 1,3-butylene glycol and glycerin, water, and oil to be stirred in Definition A is, as a guideline, preferably 10 to 400 ml, more preferably 30 to 300 ml.

[0128] Whether or not "all of the oil agent is dispersed as emulsified droplets" in Definition A can be determined by checking whether or not the oil agent has undergone phase separation and floated to the top. This determination can be made visually. If the oil agent has undergone phase separation and floated, it can be determined that "all of the oil agent has been dispersed as emulsified droplets" has not been achieved.

[0129] The oils listed in Group A in Definition A may be selected singly or in combination of two or more. Preferably, only one is selected and used.

[0130] The stirring force in the emulsification step preferably satisfies the condition defined in Definition B below. [Definition B] When 2 parts by mass of a polyoxyethylene ester ether type nonionic surfactant, 12 parts by mass of a solution containing 1,3-butylene glycol and glycerin in a 1:1 ratio, and 21 parts by mass of water are mixed at room temperature to prepare an aqueous solution, and then 65 parts by mass of an oil selected from mineral oil, triethylhexanoin, and olive fruit oil are stirred at room temperature to prepare 100 parts by mass of an emulsion composition, the stirring force is sufficient to disperse all of the oil as emulsified droplets.

[0131] By stirring with the stirring force defined in Definition B, a more stable emulsion composition can be produced without phase separation.

[0132] The explanation in Definition A can be applied directly to the specific aspects of the "polyoxyethylene ester ether type nonionic surfactant" in Definition B. In addition, the explanation in Definition A can be applied directly to the volume of the mixture of emulsifier, 1,3-butylene glycol and glycerin, water, and oil to be stirred in Definition B.

[0133] The oils listed in definition B may be selected singly or in combination of two or more, but preferably, only one is selected and used.

[0134] Whether or not "all of the oil is dispersed as emulsified droplets" in definition B has been achieved can be determined by checking whether or not the oil has phase-separated and floated to the top, as described above. This determination can be made visually. If no oil is observed to have phase-separated and floated, it can be determined that "all of the oil is dispersed as emulsified droplets" has been achieved.

[0135] In the emulsification step, it is preferable to emulsify using a stirrer that satisfies the conditions defined in Definition C below. [Definition C] When 2% by mass of the water-soluble copolymer, 88% by mass of water, and 10% by mass of squalane are stirred at room temperature, the proportion of the squalane that cannot be dispersed as emulsified droplets can be less than 1% by mass.

[0136] The proportion of the squalane that cannot be dispersed as emulsified droplets in Definition C is less than 1% by mass, preferably less than 0.5% by mass, and more preferably less than 0.1% by mass.

[0137] By using a stirrer that satisfies the conditions defined in Definition C, an emulsion composition without separation can be easily produced. A preferred example of a mixer that satisfies the conditions defined in Definition C is a hand blender.

[0138] In the emulsification step, it is preferable to emulsify using a stirrer that satisfies the conditions defined in Definition D below. [Definition D] When 2% by mass of the water-soluble copolymer, 88% by mass of water, and 10% by mass of squalane are stirred at room temperature, the median diameter of the emulsion droplets can be set to 30 μm or less.

[0139] The median diameter in definition D is 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less.

[0140] By using a mixer that satisfies the conditions defined in Definition D, an emulsion composition with better stability can be produced. A preferred example of a mixer that satisfies the conditions defined in Definition D is a hand blender.

[0141] In the emulsification step, it is preferable to emulsify so that the median diameter of the emulsified droplets is 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. In the present invention, the use of the water-soluble copolymer makes it possible to produce a stable emulsion composition with small emulsion droplets.

[0142] The median diameter can be measured by observing an image under an optical microscope.

[0143] In the emulsification step, it is preferable to emulsify using a stirrer that satisfies the conditions defined in Definition E below. [Definition E] When a mixture of 100 g of a carboxyvinyl polymer aqueous solution with a viscosity of 26,450 mPa·s or greater measured under the following conditions and 1 mL of a 0.5 wt% Red No. 504 aqueous solution is added dropwise and placed in a 200 mL beaker, the stirrer is clamped in place and the mixture is stirred continuously at 20°C for 5 minutes, but the entire mixture cannot be dyed uniformly. [conditions] Equipment used: B-type viscometer (Shibaura Systems Co., Ltd.) Temperature: 20℃ Rotation speed: 12 rpm Rotor: No. 4 Time: 60sec

[0144] A preferred example of a mixer that satisfies the conditions defined by Definition E is a milk foamer.

[0145] The viscosity of the aqueous carboxyvinyl polymer solution in Definition E is preferably 22,000 mPa·s or more, more preferably 20,000 mPa·s or more, even more preferably 1,800 mPa·s or more, even more preferably 16,000 mPa·s or more, still more preferably 15,500 mPa·s or more, and particularly preferably 15,150 mPa·s or more.

[0146] <4> Kit for preparing emulsion composition The present invention also relates to a kit for preparing an emulsion composition. The emulsion composition preparation kit of the present invention includes, as a component thereof, a first packaging container filled with the above-mentioned water-soluble copolymer. The water-soluble copolymer filled in the first packaging container may be in a non-liquid form such as a solid or powder, but is preferably filled in a liquid form. Specifically, the water-soluble copolymer is preferably filled in the first packaging container in a state dispersed in water.

[0147] When the first packaging container is filled with the aqueous dispersion of the water-soluble copolymer described above, the content of the water-soluble copolymer in the aqueous dispersion is not particularly limited, but as a guideline, it can be preferably 0.01 to 99% by mass, more preferably 1 to 90% by mass.

[0148] The volume of the aqueous dispersion of the water-soluble copolymer filled in the first packaging container is not particularly limited, but as a guideline, it is preferably 1 to 1000 ml, more preferably 10 to 500 ml.

[0149] The emulsion composition preparation kit of the present invention includes, as a component thereof, a second packaging container filled with an oil phase component. The oil phase component filled in the second packaging container may be solid or liquid at room temperature, but is preferably liquid at room temperature. If the oil phase component filled in the second packaging container is solid at room temperature, the second packaging container is heated in a hot water bath or the like to liquefy the oil phase component before use.

[0150] The volume of the oil phase component filled into the second packaging container is not particularly limited, but as a guideline, it is preferably 1 to 1000 ml, more preferably 10 to 500 ml.

[0151] The oil phase component to be filled into the second packaging container is the above-mentioned " <2> Examples of oils include those described in the section "Method for producing emulsion composition," such as liquid oils, solid oils, waxes, hydrocarbon oils, higher fatty acids, higher alcohols, synthetic ester oils, and silicone oils.

[0152] The oil phase component to be filled into the second packaging container is the same as that described above. <2> It is preferable that the oily agent described in the section "Method for producing emulsion composition" be used as the base oil. Although there are no particular limitations, specifically, as a guideline, the oily agent accounts for preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more of the oily phase components. The total amount of the oily phase components to be filled into the second packaging container is determined by the above-mentioned " <2> It may be composed of the oil agent explained in the section "Method for producing emulsion composition."

[0153] The oil phase component to be filled into the second packaging container may be in a form that contains an oil-soluble optional component other than the above-mentioned base oil in advance. <2> Of the optional ingredients listed in the section "Method for producing emulsion composition," oil-soluble ingredients may be appropriately blended.

[0154] The kit for preparing an emulsion composition of the present invention includes, as a component thereof, a third packaging container filled with an aqueous phase component. The aqueous phase component filled in the third packaging container may be entirely water, preferably purified water. Alternatively, the aqueous phase component may be an aqueous solution or aqueous dispersion in which any component is dissolved or dispersed.

[0155] The volume of the aqueous phase component filled in the third packaging container is not particularly limited, but as a guideline, it is preferably 1 to 1000 ml, more preferably 10 to 500 ml.

[0156] When the third packaging container is filled with an aqueous solution or aqueous dispersion, the content of the solute or dispersoid is not particularly limited, but is preferably 0.01 to 90% by mass, more preferably 0.1 to 80% by mass as a guideline.

[0157] When filling the third packaging container with an aqueous solution or aqueous dispersion containing an optional component in advance, the solute or dispersoid may be any of the above-mentioned <2> Among the optional ingredients listed in the section "Method for producing emulsion composition," water-soluble or hydrophilic ingredients can be appropriately blended.

[0158] The third packaging container may be filled with an aqueous dispersion of the water-soluble copolymer. That is, the embodiment may be designed to prepare the emulsion composition by mixing the oil phase component filled in the second packaging container with the aqueous phase component containing the water-soluble copolymer filled in the third packaging container. In this case, the first packaging container filled with the water-soluble copolymer or its aqueous dispersion may not be provided, and only the second packaging container and the third packaging container may be included.

[0159] The preparation kit of the present invention enables consumers to prepare homemade emulsion compositions at home. That is, the water-soluble copolymer, oil phase component, and aqueous phase component filled in the first to third packaging containers, respectively, are poured into any container to prepare a mixture, and the mixture can be stirred to prepare the emulsion composition. The blending ratio of the water-soluble copolymer, oil phase component, and aqueous phase component can be adjusted to suit the consumer's preference. Furthermore, any active ingredient can be blended as needed to suit the consumer's preference. In other words, the preparation kit of the present invention allows the preparation of an original emulsion composition.

[0160] When preparing an emulsion composition using the preparation kit of the present invention, it is not necessary to use an industrial stirring device with a strong stirring force. Even when a household stirrer with poor stirring force is used, an emulsion composition without separation of the oil phase and the aqueous phase can be easily prepared.

[0161] An agitator may be included as a component of the production kit of the present invention. When an agitator is included as a component of the production kit, specific embodiments such as the type of agitator and agitation power are described in the above " <2> The matters described in "Method for producing emulsion composition" can be applied as they are.

[0162] The preparation kit of the present invention may also include a container used for preparing the emulsion composition as a component thereof. A preferable example of this container is one with a graduated scale, and more preferably, a graduated beaker. The provision of a graduated container makes it easy for consumers to adjust and check the blending ratio of the water-soluble copolymer, oil phase component, and aqueous phase component.

[0163] Furthermore, the preparation kit may include an instruction manual that describes the approximate blending ratios of the water-soluble copolymer, oil phase component, and aqueous phase component.

[0164] The preparation kit may include a fourth packaging container filled with a plant extract that has a beneficial effect on the skin, an aromatic oil for fragrance, etc. The ingredients filled in the fourth packaging container can be blended into the emulsion composition according to the consumer's preferences.

[0165] The production kit of the present invention may be embodied in such a way that all components included in the kit are packed in a single packaging container, which facilitates transportation and sales. Furthermore, the production kit of the present invention has a high degree of freedom in terms of composition, allowing consumers to change the ingredients and their ratios to achieve the feel and comfort they prefer.

[0166] <5> Method for designing emulsion composition The present invention also relates to a method for designing an emulsion composition that is emulsified under heating. The present invention involves the step of selecting, as the aqueous phase components, components having a melting point above 40°C and / or components that do not dissolve or disperse in the aqueous phase at 40°C or below. The method also includes a step of selecting, as the oil phase component, a component having a melting point of more than 40°C and / or a component that is not soluble or dispersible in the oil phase at 40°C or lower.

[0167] The aqueous phase components and oil phase components are: <2> The matters described in "Method for producing emulsion composition" and " <3> The matters explained in "Emulsion composition" can be applied. Examples of oil phase components having a melting point of more than 40°C include waxes, higher alcohols, fatty acids, petrolatum, hardened rapeseed oil, ester oil, crosslinked methylpolysiloxane, and highly polymerized silicone.

[0168] The oil phase component is preferably one or more selected from the group consisting of squalane, isostearic acid, oleic acid, linoleic acid, linolenic acid, tri(caprylic / capric acid)glyceryl, polydimethylsiloxane, and cyclopentasiloxane. [Example]

[0169] <Test Example 1> An emulsion composition was prepared using a water-soluble copolymer (glyceryl diisostearate methacrylate / methoxy PEG-23 methacrylate) having an average molecular weight of 61,000, obtained by copolymerizing a hydrophobic monomer, glyceryl diisostearate methacrylate, with a hydrophilic monomer, methoxy PEG-23 methacrylate, in a mass ratio of approximately 3:7.

[0170] Specifically, first, an aqueous solution was prepared by mixing 1 part by mass of the above-mentioned water-soluble copolymer, 12 parts by mass of a moisturizer made by mixing 1,3-butylene glycol and glycerin in a 1:1 ratio, and 22 parts by mass of water at room temperature. To this aqueous solution, 65 parts by mass of 11 different oils with different structures listed in Table 1 were added to make a total of 150 ml of mixture, which was then stirred at high speed for 30 seconds using a household kitchen mixer (HB-1230, HadinEEon) to prepare 100 parts by mass of an emulsified composition.

[0171] For comparison, emulsion compositions were prepared under the same conditions using 2 parts by mass of a polyoxyethylene ester ether type nonionic surfactant (POE surfactant) or 0.3 parts by mass of an acrylic acid methacrylic acid copolymer (AAMA polymer) instead of the water-soluble copolymer described above. The amount of water added was adjusted to make the total 100 parts by mass.

[0172] The POE surfactant and AAMA polymer used were specifically as follows: POE surfactant: Polyoxyethylene hydrogenated castor oil AAMA Polymer: (Acrylates / C10-30 Alkyl Acrylate) Crosspolymer

[0173] Immediately after preparation, the emulsion composition was visually evaluated for separation of the oil and water phases to determine whether emulsification was successful, i.e., whether all of the oil was dispersed as emulsified droplets. The evaluation results are shown in Table 1. As a representative example, photographs of a composition using squalane as the oil agent and a POE surfactant, an AAMA polymer, and a water-soluble copolymer as the emulsifier after stirring are shown in Figures 1 and 2.

[0174] [Table 1]

[0175] As a result, the POE surfactant was unable to completely emulsify 8 of the 11 oils (Table 1). In addition, separation of the water and oil phases was observed when the AAMA polymer was used with all oils (Table 1). On the other hand, when the water-soluble copolymer was used, complete emulsification was confirmed without separation of the oil phase in all cases where 11 types of oil were used (Table 1).

[0176] The above results indicate that when the above-mentioned water-soluble copolymer is used as an emulsifier, an emulsified composition without separation of the oil phase and the aqueous phase can be produced even when a household mixer with poor mixing power is used. In other words, this indicates that by using the above-mentioned water-soluble copolymer as an emulsifier, consumers can prepare homemade emulsion compositions, more specifically emulsion cosmetics, at home using a household mixer, without using industrially used stirring devices with strong stirring power.

[0177] <Test Example 2> 1 part by mass of the water-soluble copolymer used in Test Example 1 and 88 parts by mass of water were mixed, to which 10 parts by mass of squalane was added, and the mixture was stirred at room temperature by any of the following stirring means. Hand blender (HB-1230, HadinEEon) Milk frother (RECHARGEABLE MILK FROTHER, Kitdine) Research mixer (handy homogenizer (NS360D, Microtec)) ·Hand stirring

[0178] The emulsion compositions prepared using various stirring means were observed under a microscope to confirm the size of the emulsion droplets (microscopic images are shown in FIG. 3). The median diameter was also measured under an optical microscope. The median diameters of emulsified droplets of the emulsified compositions prepared by various stirring means are shown below. Hand blender 3.9μm Milk frother 5.6μm ·Research Mixer···3.6μm Manual mixing: Measurement not possible

[0179] The above results indicate that, regardless of the stirring means employed, by using the above-mentioned water-soluble copolymer, an emulsion composition can be prepared at home without using a powerful stirrer for research or industrial use. It also shows that the use of a hand blender allows the preparation of emulsion compositions with smaller emulsion droplets and greater stability.

[0180] <Test Example 3> Using the water-soluble copolymer used in Test Example 1, emulsion compositions of Examples 1 and 2 were prepared under heating (80°C) according to the formulations shown in Table 2 below. The numbers in the table are in mass %. Additionally, the aforementioned AAMA polymer was used as an emulsifier to prepare emulsion compositions under heating in Comparative Examples 1 and 2. Furthermore, the AAMA polymer and other low-molecular-weight emulsifiers were used to prepare emulsion compositions in Comparative Examples 3 to 5. In Reference Examples 1 to 4, emulsion compositions were prepared using each emulsifier without heating. The surface condition of each emulsion composition prepared was observed with the naked eye immediately after preparation, after one week of storage at -10°C, after one month of storage at 20°C, and after one month of storage at 5°C, and evaluated according to the following evaluation criteria. Emulsified particles were also observed using an optical microscope. The results are shown in Figures 4 and 5.

[0181] (Evaluation criteria) 〇: Fully emulsified △: A small amount of oil is floating ×: The emulsion is uneven or oil is floating ××: A large amount of oil is floating

[0182] [Table 2]

[0183] From the results of FIGS. 4 and 5, the emulsion compositions of Examples 1 and 2 were emulsion compositions in which no floating oil was observed immediately after preparation, and no separation of the oil phase and the water phase occurred. On the other hand, in the emulsion compositions of Comparative Examples 1 and 2, a large amount of floating oil was observed immediately after preparation. This result indicates that by using the above-mentioned water-soluble copolymer as an emulsifier, it is possible to prepare an emulsion composition with higher emulsion stability under heating than when conventional polymeric emulsifiers are used. Furthermore, the results show that a stable emulsion composition can be prepared even when the above-mentioned water-soluble copolymer is used alone as an emulsifier.

[0184] In Comparative Example 3, in which AAMA polymer and sorbitan stearate were used in combination, a small amount of oil floating was observed immediately after preparation, while in Comparative Example 4, in which AAMA polymer, PEG stearate, and sorbitan stearate were used in combination, no oil floating was observed and the entire amount was emulsified. These results show that, in the preparation of emulsion compositions using conventional polymer emulsifiers, good emulsion compositions can be prepared by using them under heating and in combination with other emulsifiers, but according to the present invention, good emulsion compositions can be prepared by using the above-mentioned water-soluble copolymer alone as an emulsifier.

[0185] 4 and 5, when the emulsion compositions of Examples 1 and 2 were prepared and stored under various temperature conditions, slight oil floating was observed in some of the emulsions, but this did not significantly impair the stability of the emulsion. On the other hand, when the emulsion compositions of Comparative Examples 1 and 2 were stored under the same conditions, a large amount of oil floating was observed. These results show that by using the aforementioned water-soluble copolymer alone as an emulsifier and emulsifying under heating, it is possible to prepare an emulsion composition that has no problems with emulsion stability and has superior emulsion stability compared to conventional polymer emulsifiers. [Industrial Applicability]

[0186] The present invention can be applied to a process for producing an emulsion composition using a polymer emulsifier.

Claims

1. one or more structural units (a) derived from a hydrophobic monomer represented by the following general formula (II); a water-soluble copolymer having, as an essential structural unit, one or more structural units (b) derived from a hydrophilic monomer; An oil phase component, Aqueous phase components; an emulsification step of emulsifying the above under heating, The hydrophilic monomer is a hydrophilic monomer represented by the following general formula (IV): the mass ratio of the structural unit (a) to the structural unit (b) is 10:90 to 50:50; In the emulsification step, the emulsion is substantially free of emulsifiers other than the water-soluble copolymer. A method for producing an emulsion composition. General formula (II) (II) (R in general formula (II) ３ is a methyl group, and R ４ , R ５ is a 16-methylheptadecanoyl group. X represents a group in which an OH group has been eliminated from a trihydric alcohol. General formula (IV) (IV) (In general formula (IV), R 10 is a methyl group, R 11 is an ethylene group, and R 12 is a methyl group. n is 23.)

2. The production method according to claim 1 , wherein the emulsification step is a step of emulsifying the water-soluble copolymer, the oil phase component, and the aqueous phase component by stirring under heating.

3. The method according to claim 1 or 2, wherein the temperature in the emulsification step is higher than 40°C.

4. The manufacturing method described in any one of claims 1 to 3, wherein the "substantially free of emulsifiers other than the water-soluble copolymer" means that the amount of emulsifiers other than the water-soluble copolymer added is 0.3 mass% or less relative to the total amount of the emulsion composition.

5. The method according to any one of claims 1 to 4, wherein the aqueous phase components include a component having a melting point of more than 40°C and / or a component that does not dissolve or disperse in the aqueous phase at 40°C or lower.

6. The method according to any one of claims 1 to 5, wherein the oil phase component comprises a component having a melting point of more than 40°C and / or a component that is not soluble or dispersible in the oil phase at 40°C or lower.

7. The method according to any one of claims 1 to 6, wherein the emulsion composition is a skin topical agent.

8. A method for designing an emulsion composition that is emulsified under heating, comprising: selecting, as aqueous phase components, components having a melting point above 40°C and / or components that do not dissolve or disperse in the aqueous phase at above 40°C; selecting, as oil phase components, components having a melting point of greater than 40°C and / or components that are not soluble or dispersible in the oil phase at temperatures greater than 40°C; As an emulsifier, one or more structural units (a) derived from a hydrophobic monomer represented by the following general formula (II), and selecting a water-soluble copolymer having, as an essential structural unit, one or more structural units (b) derived from a hydrophilic monomer; The hydrophilic monomer is a hydrophilic monomer represented by the following general formula (IV): the mass ratio of the structural unit (a) to the structural unit (b) is 10:90 to 50:50; In the step of selecting the water-soluble copolymer, the composition is substantially free of emulsifiers other than the water-soluble copolymer. A method for designing an emulsion composition. General formula (II) (II) (R in general formula (II) ３ is a methyl group, and R ４ , R ５ is a 16-methylheptadecanoyl group. X represents a group in which an OH group has been eliminated from a trihydric alcohol. General formula (IV) (IV) (In general formula (IV), R 10 is a methyl group, R 11 is an ethylene group, and R 12 is a methyl group. n is 23.)

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