WO2024142911A1 - Water-in-oil emulsion cosmetic - Google Patents

Abstract

[Problem] The purpose of the present invention is to provide a water-in-oil emulsion cosmetic that can be efficiently manufactured and that achieves enhanced stability in high-temperature and low-temperature ranges. [Solution] A water-in-oil emulsion cosmetic according to the present invention is characterized by containing: (A) an ester formed between a fatty acid having 10-22 carbon atoms and a polyhydric alcohol having three or more hydroxyl groups in a molecule thereof; (B) one or more types of substances selected from (B-1) an amino acid or a salt thereof and (B-2) a divalent or higher inorganic salt; (C) a glyceryl (behenic acid/eicosandioic acid); and (D) water.

Description

Water-in-oil emulsion cosmetics

The present invention relates to a water-in-oil emulsion cosmetic that can be produced efficiently and has improved stability at high and low temperatures.

In the field of cosmetics, there are various techniques for emulsifying water-soluble ingredients such as water and moisturizers with oil-soluble ingredients such as emollients, including emulsification methods using hydrophilic or lipophilic surfactants, emulsification methods using α-gels that are liquid crystalline with higher alcohols and hydrophilic surfactants, non-aqueous emulsification methods, mechanical emulsification methods, and amino acid gel emulsification methods.

Among them, the amino acid gel emulsification method makes it possible to maintain a stable emulsified state in water-in-oil emulsions that contain a large amount of water by promoting the orientation of specific surfactants at the interface through the salting-out effect of amino acids (see, for example, Patent Document 1).

　Wax has traditionally been blended into emulsified cosmetics made with amino acid gel emulsions, and the inclusion of wax has the advantage of increasing the stability of the amino acid gel emulsion. On the other hand, the inclusion of wax makes it easier for bumps to form during production (a state in which the wax precipitates as a solid), and a cooling process is required to prevent these bumps, which creates the problem of making production more complicated. In addition, the inclusion of wax tends to reduce stability at high and low temperatures, and to result in a texture that is more specialized and rich in flavor when used.

Therefore, there is a demand for water-in-oil emulsion cosmetics made using amino acid gel emulsification to be produced more efficiently and have greater stability at high and low temperatures.

Japanese Patent Application Laid-Open No. 8-126832

The present invention aims to provide a water-in-oil emulsion cosmetic that can be produced efficiently and has improved stability at high and low temperatures.

The inventors conducted extensive research to solve the above problems, and discovered that the use of an ester of a fatty acid having 10 to 22 carbon atoms and a polyhydric alcohol having at least three hydroxyl groups in the molecule, and one or more selected from an amino acid or its salt and a divalent or higher inorganic salt, promotes orientation of the surfactant at the interface, and further that the use of glyceryl (behenate/eicosanedioate) as an oil phase thickener makes it possible to obtain a cosmetic composition with high emulsion stability both at high and low temperatures, thus completing the present invention.

That is, the present invention provides
(A) an ester of a fatty acid having 10 to 22 carbon atoms and a polyhydric alcohol having at least three hydroxyl groups in the molecule; (B) one or more selected from the following (B-1) and (B-2):
The present invention provides a water-in-oil emulsion cosmetic, comprising: (B-1) an amino acid or a salt thereof; (B-2) a divalent or higher inorganic salt; (C) glyceryl (behenate/eicosanedioate); and (D) water.

The present invention, by adopting the above-mentioned configuration, can obtain a water-in-oil type emulsion cosmetic that contains a large amount of water and has high emulsion stability over a wide temperature range. In addition, it can be produced more efficiently than conventional emulsion cosmetics using amino acid gel emulsification. Furthermore, by using dimethylsilylated silica (E) in addition to the above-mentioned components (A) to (D), it is possible to obtain a water-in-oil type emulsion cosmetic that has a heavy and rich feel and spreads well when applied.

In the present invention, "heavy feeling" refers to a feeling of moderate weight and elasticity during application, and "rich feeling" refers to the feeling that the cosmetic remains on the skin as if it covers the skin after it has been absorbed into the skin.

The water-in-oil emulsion cosmetic of the present invention is characterized by containing (A) an ester of a fatty acid having 10 to 22 carbon atoms and a polyhydric alcohol having at least three hydroxyl groups in the molecule, (B) one or more selected from (B-1) amino acids or salts thereof and (B-2) divalent or higher inorganic salts, (C) glyceryl (behenate/eicosanedioate), and (D) water. Each component constituting the cosmetic of the present invention is described in detail below.

<(A) Ester of fatty acid having 10 to 22 carbon atoms and polyhydric alcohol having at least three hydroxyl groups in the molecule>
The (A) ester of a fatty acid having 10 to 22 carbon atoms and a polyhydric alcohol having at least three hydroxyl groups in the molecule (hereinafter, may be referred to simply as "component (A)") blended in the cosmetic preparation according to the present invention is an ester of a saturated fatty acid or unsaturated fatty acid having 10 to 22 carbon atoms and a polyhydric alcohol having at least three hydroxyl groups in the molecule, and is liquid at room temperature (about 25°C).

The polyhydric alcohols constituting component (A) have three or more hydroxyl groups, and specific examples include glycerin, diglycerin, triglycerin, tetraglycerin, pentaglycerin, hexaglycerin, octaglycerin, nonaglycerin, decaglycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitan, sorbitol, etc. The fatty acids constituting component (A) include lauric acid, palmitic acid, myristic acid, stearic acid, caprylic acid, capric acid, oleic acid, linoleic acid, ricinoleic acid, isooctanoic acid, isomyristic acid, isopalmitic acid, and isostearic acid, etc.

Esters generally refer to monoesters, diesters, triesters, and some tetraesters and pentaesters, either alone or in mixtures. In the case of mixtures, the preferred mixing ratio varies depending on the type of carboxylic acid and the number of hydroxyl groups in the polyhydric alcohol. For example, in the case of glycerin esters with three hydroxyl groups, a mixture of monoesters and diesters is preferred for fatty acids with 18 carbon atoms. In addition, in the case of fatty acids with 18 carbon atoms, esters with different numbers of hydroxyl groups are preferred, for example, for glycerin or trimethylolpropane with three hydroxyl groups, a mixture of monoesters and diesters with some triesters with diglycerol with four hydroxyl groups, and a mixture of diesters, triesters, and some tetraesters with sorbitol with six hydroxyl groups.

Examples of component (A) include glyceryl mono-2-heptylundecanoate, trimethylolpropane mono-2-heptylundecanoate, diglycerin di-2-heptylundecanoate, glyceryl mono-9-methylheptadecanoate, trimethylolpropane mono-9-methylheptadecanoate, diglyceryl di-9-methylheptadecanoate, pentaerythrityl di-9-methylheptadecanoate, glyceryl monooleate, trimethylolpropane monooleate, diglyceryl dioleate, glyceryl diricinoleate, sorbitan mono(di)oleate, and sorbitan di(tri)oleate.
Among them, as component (A), glycerin fatty acid ester is preferable, and glycerin fatty acid ester having a saturated or unsaturated fatty acid having 18 carbon atoms is more preferable. As component (A), it is preferable to use glyceryl oleate and polyglyceryl diisostearate.
As the component (A) of the present invention, one of the above substances may be used alone, or two or more of them may be used in combination.

The lower limit of the amount of component (A) relative to the total amount of the cosmetic is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more. The upper limit is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less, relative to the total amount of the cosmetic. Thus, examples of the amount range include 0.5 to 15% by mass, 1 to 10% by mass, etc. If the amount of component (A) is less than 0.5% by mass, sufficient stability may not be obtained, and if it exceeds 15% by mass, usability tends to decrease.

<(B) One or more selected from amino acids or salts thereof and divalent or higher inorganic salts>
The component (B) blended in the cosmetic preparation according to the present invention is one or more selected from (B-1) an amino acid or a salt thereof, and (B-2) a divalent or higher inorganic salt (hereinafter, sometimes simply referred to as “component (B)”).
In the conventional amino acid gel emulsification method, the salting-out effect of amino acids is promoted by using amino acids or their salts, and the emulsion state is stably maintained. In the present invention, it has been found that the orientation of a specific surfactant at the interface is also promoted by using a divalent or higher inorganic salt instead of amino acids or their salts.

The (B-1) amino acid or salt thereof of the present invention (hereinafter, may be simply referred to as "component (B-1)") is not particularly limited as long as it is an amino acid or salt thereof that can generally be incorporated into cosmetics. Examples of amino acids include L-amino acids such as L-alanine, β-alanine, L-arginine hydrochloride, L-asparagine monohydrate, L-aspartic acid, L-citrulline, L-glutamic acid, L-glutamic acid hydrochloride, L-glutamine, glycine, L-histidine, L-histidine hydrochloride monohydrate, L-hydroxyproline, L-isoleucine, L-leucine, L-lysine, L-lysine hydrochloride, L-ornithine hydrochloride, L-proline, L-phenylalanine, L-serine, L-threonine, L-tryptophan, L-tyrosine, L-valine, L-dopa, and L-α-aminobutyric acid. The same applies to D- and DL-isomers. Among these, it is preferable to select from L-glutamic acid, glycine, L-hydroxyproline, L-alanine, β-alanine, L-proline, and L-serine. Examples of the salt include monovalent metal salts such as sodium, potassium, and lithium, and divalent metal salts such as calcium and magnesium.
The component (B-1) of the present invention is preferably selected from sodium L-aspartate, potassium L-aspartate, sodium L-glutamate, and potassium L-glutamate.

The divalent or higher inorganic salt (B-2) of the present invention (hereinafter, may be simply referred to as "component (B-2)") is not particularly limited as long as it is a divalent or higher inorganic salt that can generally be incorporated into cosmetics. Inorganic acids that can be used as inorganic salts include hydrochloric acid, phosphoric acid, nitric acid, sulfuric acid, boric acid, and hydrofluoric acid, and divalent salts include magnesium, calcium, barium, etc.
The component (B-2) of the present invention is preferably selected from calcium chloride, magnesium chloride, and magnesium sulfate.

The lower limit of the amount of component (B) relative to the total amount of the cosmetic is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more. The upper limit is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, relative to the total amount of the cosmetic. Thus, examples of the amount range include 0.5 to 10% by mass, 1 to 5% by mass, etc. If the amount of component (B) is less than 0.5% by mass, sufficient stability may not be obtained, and if it exceeds 10% by mass, usability tends to decrease.

<(C) Glyceryl (behenate/eicosanedioate)>
The (C) (behenic acid/eicosanedioic acid) glyceryl (hereinafter, sometimes simply referred to as "component (C)") of the present invention refers to an oligomer obtained by condensing a mixed fatty acid consisting of behenic acid and eicosanedioic acid with glycerin.
An example of a commercially available product of component (C) is Nomcoat HK-G (manufactured by Nisshin Oillio Group, Ltd.).

The lower limit of the blending amount of the (C) component is preferably 0.2% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.8% by mass or more, based on the total amount of the cosmetic. The upper limit is preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 5% by mass or less, and even more preferably 3% by mass or less, based on the total amount of the cosmetic. Thus, examples of the blending amount range include 0.2 to 10% by mass, 0.5 to 7% by mass, and 0.8 to 5% by mass. If the blending amount of the (C) component is less than 0.2% by mass, sufficient stability may not be obtained, and if it exceeds 10% by mass, stability tends to deteriorate.
Furthermore, the blending ratio of component (C) in the oil phase (total oily components) in the cosmetic is preferably 2 to 20% by mass, and more preferably 2.5 to 12%. Here, the "oil phase" or "total oily components" refers to the total of the components that constitute the water-in-oil emulsion cosmetic of the present invention and that are mixed with the oil to constitute the oil phase. For example, in Table 2 described below, the oil phase is the sum of the components classified as component (A), oil, component (C), and component (E).

The water (D) blended in the cosmetic of the present invention may be selected as necessary from ion-exchanged water, purified water, tap water, natural water, etc. The blending amount is the balance (mass % relative to the total amount of the cosmetic) relative to the sum of the essential components of the present invention and other optional blending components. In general, the amount is 30 to 70 mass % of the total amount of the cosmetic, and preferably 40 to 60 mass %.

In the water-in-oil emulsion cosmetic of the present invention, by blending the above-mentioned components (A) to (C), it is possible to stably blend many aqueous components. For example, it is preferable that the cosmetic of the present invention contains approximately 20 to 80 mass %, 30 to 75 mass %, or 50 to 70 mass % of aqueous components as the internal phase relative to the total amount of the cosmetic.

In the water-in-oil emulsion cosmetic of the present invention, by using dimethylsilylated silica (E) in addition to the above-mentioned components (A) to (C), it is possible to obtain a cosmetic that has a heavy, rich feel when used and spreads easily when applied.

Dimethylsilylated silica (E) (hereinafter, may be simply referred to as "ingredient (E)") that can be blended in the cosmetic preparation of the present invention refers to silica having a primary particle size of 5 to 50 nm and a specific surface area of 90 to 300 ^m2 /g, the surface of which has been subjected to a hydrophobic treatment with dimethyldichlorosilane.
Commercially available products of component (E) include Aerosil (registered trademark) R972, R974, R9200, R976, and R976S (manufactured by Nippon Aerosil Co., Ltd.).

It is preferable to incorporate component (E) in an amount sufficient to ensure that the effects of the incorporation are recognized, and to the extent that an excessive amount does not cause adverse effects such as impairing the feel of use. The preferred amount of component (E) in the cosmetic composition of the present invention is approximately 0.5 to 5% by mass, or 1 to 3% by mass, based on the total amount of the cosmetic composition.

In addition to the above-mentioned components, the cosmetic composition of the present invention may contain other optional components that are normally used in cosmetics, pharmaceuticals, and other skin topical preparations, as necessary, within the scope of not impairing the purpose and effects of the present invention. Examples of other optional components include oils other than component (A), powder components, UV absorbers, nonionic, cationic, and silicone-based surfactants, lower alcohols, polyhydric alcohols, chelating agents, pH adjusters, antioxidants, fragrances, preservatives, disinfectants, various drugs, and the like. However, they are not limited to these examples.

Oils other than component (A) include hydrocarbon oils such as mineral oil, hydrogenated polydecene, isohexadecane, isododecane, ozokerite, squalane, squalene, pristane, paraffin, isoparaffin, ceresin, petrolatum, hydrogenated polyisobutene, and olefin oligomers; pentaerythrityl tetraethylhexanoate, cetyl ethylhexanoate, jojoba oil, di(phytosteryl/octyldodecyl) lauroyl glutamate, triisostearin, glyceryl diisostearate, triethylhexanoin, dimer dilinoleic acid (phytosteryl/isostearyl/cetyl/stearyl/behenyl), isopropyl palmitate, ethylhexyl palmitate, and myris myristate. ester oils such as ethyl, isopropyl myristate, tripropylene glycol dipivalate, diisopropyl sebacate, and isodecyl neopentanoate; chain silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylhydrogenpolysiloxane; cyclic silicone oils such as octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane; and liquid oils and fats such as linseed oil, camellia oil, macadamia nut oil, corn oil, mink oil, olive oil, avocado oil, camellia oil, castor oil, safflower oil, rapeseed oil, soybean oil, peanut oil, triglycerin, glycerin trioctanoate, and glycerin triisopalmitate.

The cosmetic composition according to the present invention may contain wax to the extent that it does not affect the effects of the present invention. When wax is contained, it is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less. The cosmetic composition according to the present invention also includes an embodiment in which no wax is contained. Here, wax refers to waxes with a melting point of 60°C or more at 1 atmosphere, such as beeswax, Japan wax, candelilla wax, carnauba wax, etc.; and solid hydrocarbon oils such as polyolefin wax, microcrystalline wax, solid paraffin, and synthetic wax.

The cosmetic of the present invention can be produced according to a conventional production method using amino acid gel emulsification. That is, the powder component and the oil phase component are mixed while heating as necessary to obtain an oil phase component mixture in which the powder component is uniformly dispersed, and a mixed solution (gel phase) obtained by dissolving the components (A) and (B) of the present invention and a portion of the water is mixed with the oil phase component mixture and emulsified, and further, an aqueous phase component mixture obtained by mixing and dissolving the remaining water and the aqueous component is added to the emulsion, and further mixed and emulsified to obtain a water-in-oil emulsion cosmetic.

The cosmetic of the present invention can be formulated into a paste, cream, balm, or other formulation. In particular, it is suitable for use as a cream cosmetic that is filled into a wide-mouth container or tube.

The present invention will be described in more detail below with reference to examples, but the present invention is in no way limited by these. Unless otherwise specified, the blending amount is indicated as mass % relative to the system in which the component is blended. Before describing each example in detail, the evaluation method used will be explained.

1. Stability Evaluation Each example of cream-like water-in-oil emulsion cosmetic was prepared and allowed to stand at room temperature for 4 weeks, after which the appearance was visually observed and evaluated according to the following evaluation criteria. The appearance was also evaluated in the same manner after leaving the cosmetic at a low temperature (0°C) and a high temperature (50°C) for 4 weeks.
(Evaluation criteria)
A: No change in appearance.
B: Minor changes are observed on the surface of the cosmetic, but do not affect use.
C: Slight separation of water (low temperature) or solidification (high temperature) is observed.
D: Separation of water (low temperature) or solidification (high temperature) is noticeable.

2. Evaluation of texture when used A practical test was carried out by 10 expert panelists for each of the prepared cosmetics. The texture when each sample was applied to the skin (thickness, richness) was evaluated according to the following criteria. Here, "thickness" means a feeling of moderate weight and elasticity during application, and "richness" means a lingering feeling of the cosmetic covering the skin after the cosmetic is absorbed into the skin.
<Evaluation criteria>
A: Eight or more people rated it as having a rich and full-bodied flavor.
B: 5 to 7 people rated it as having a rich and full-bodied flavor.
ST: 2 to 4 people rated it as having a rich and full-bodied flavor.

(Examples and Comparative Examples)
A water-in-oil emulsion cosmetic (cream) having the composition shown in Tables 1 and 2 below was prepared by dispersing a powder component in an oil component mixed using a homomixer, and then adding a gel phase and an aqueous component, which were separately mixed, in that order, and emulsifying the cosmetic. The stability and feel of use of the prepared cosmetic were evaluated according to the evaluation methods described above. The results are also shown in the tables.

The oil phase thickeners used in Comparative Examples 1 to 4 in Table 1 are oil phase thickeners that are generally used in water-in-oil emulsion cosmetics. The cosmetic of Comparative Example 5 is a conventional water-in-oil emulsion cosmetic made by emulsifying with amino acid gel, in which wax is blended into an emulsion made by emulsifying with amino acid gel.
The cosmetic of Comparative Example 2 had poor stability and could not be evaluated at high and low temperatures. The cosmetic of Comparative Examples 1, 3 and 4 had poor temporal stability, particularly at high temperatures. The cosmetic of Comparative Example 5 contained a large amount of wax, so a rapid cooling step was required in the production, and the stability was poor not only at high temperatures but also at low temperatures.
On the other hand, the cosmetic composition of Example 1, which used (C) glyceryl (behenate/eicosanedioate) as the oil phase thickener, had excellent stability over all temperature ranges.

Cosmetics were prepared by varying the amount of component (A) of the present invention. Examples 2 and 3 are examples in which the amount of component (C) is different. All of the cosmetics had excellent stability in both low and high temperature ranges.
Compared with the cosmetic of Example 1, many panelists evaluated the cosmetics of Examples 2 to 7, which contained the component (E), as having a heavy feel and richness.
Furthermore, compared to the cosmetic of Example 2, in which the blending ratio of component (C) in the oil phase was less than 2 mass%, the cosmetics of Examples 3 to 7, in which the blending ratio was 2 mass% or more, showed further improved emulsion stability.
Therefore, by using component (E) in addition to components (A) to (D) of the present invention, it is possible to obtain a cosmetic preparation that has excellent emulsion stability over a wide temperature range and that has a rich and full-bodied feel.

Although the results are not shown in the table, the cosmetics of Examples 1 to 7 were evaluated for their spreadability during application (the state in which the cosmetics spread when applied to the skin). Compared to the cosmetic of Example 1, the cosmetics of Examples 2 to 7 had a moderate weight during application and were superior in spreadability. Therefore, by blending component (E) into the cosmetic of the present invention, it is possible to improve the spreadability during application.

Claims (8)

(A) an ester of a fatty acid having 10 to 22 carbon atoms and a polyhydric alcohol having at least three hydroxyl groups in the molecule; (B) one or more selected from the following (B-1) and (B-2):
A water-in-oil emulsion cosmetic comprising: (B-1) an amino acid or a salt thereof; (B-2) a divalent or higher inorganic salt; (C) glyceryl (behenate/eicosanedioate); and (D) water. The water-in-oil emulsion cosmetic according to claim 1, wherein the component (A) is a glycerin fatty acid ester. The water-in-oil emulsion cosmetic according to claim 1, wherein the component (A) is a glycerin fatty acid ester having a saturated or unsaturated fatty acid having 18 carbon atoms. The water-in-oil emulsion cosmetic according to claim 1, wherein the component (A) is one or more selected from glyceryl oleate and polyglyceryl diisostearate. The water-in-oil emulsion cosmetic according to claim 1, wherein the component (B) is (B-1) an amino acid or a salt thereof. The water-in-oil emulsion cosmetic according to claim 1, wherein the component (B) is glutamic acid or a salt thereof. The water-in-oil emulsion cosmetic according to claim 1, further comprising (E) dimethylsilylated silica. The water-in-oil emulsion cosmetic according to claim 1, wherein the blending ratio of component (C) in the oil phase of the cosmetic is 2 to 20% by mass.