CN118717558A - Oil-in-water emulsion cosmetics - Google Patents

Abstract

The present invention relates to an oil-in-water emulsion cosmetic. An object of the present invention is to provide an oil-in-water emulsion cosmetic which has excellent dispersion stability of fine zinc oxide particles and is less likely to cause sedimentation of aggregates of fine zinc oxide particles. The oil-in-water emulsion cosmetic composition of the present invention is characterized by comprising an aqueous phase, an oil phase dispersed in the aqueous phase, and a powder dispersed in the oil phase, wherein the oil phase comprises (A) an amino-modified silicone and the powder comprises (B) a fine-particle zinc oxide covered with a hydrophobized silica.

Description

Oil-in-water emulsion cosmetics

Technical Field

The present invention relates to an oil-in-water emulsified cosmetic, and more specifically to an oil-in-water emulsified cosmetic having excellent dispersion stability of fine zinc oxide particles and being less likely to cause sedimentation of aggregates of the fine zinc oxide particles.

Background Art

Oil-in-water emulsion cosmetics provide a refreshing and moist touch when applied to the skin, and are therefore widely used as bases for skin external preparations such as skin care and body care that are applied directly to the skin. In recent years, the protection of the skin from ultraviolet rays has become a daily routine, and therefore, the importance of UV care has also increased in skin external preparations based on oil-in-water emulsion cosmetics.

When an ultraviolet scattering agent is added to an oil-in-water emulsion cosmetic, in order to achieve an excellent moist feeling and a refreshing feeling during use, it is widely practiced to hydrophobize the surface of fine-grained powders such as titanium oxide and zinc oxide and disperse them in the internal oil phase of the oil-in-water emulsion cosmetic. For example, the following scheme has been proposed: adding hydrophobized powders and various dispersants to the oil phase component, treating them with a medium stirring mill with a high crushing force such as a bead mill, thereby preparing a dispersion, and homogenizing and mixing the dispersion with the aqueous phase (Patent Documents 1 to 4).

However, if a load such as temperature change or vibration is applied over time during storage, a part of the powder dispersed in the inner oil phase is transferred to the outer water phase, sometimes forming aggregates and settling to the bottom of the container, or causing blockage at the mouth of the container. In particular, if a representative ultraviolet scattering agent, i.e., fine-grained zinc oxide, is used as the powder, zinc ions are dissolved into the water phase and form a complex with the agent present in the water phase, which is prone to sedimentation and blockage. In cosmetics for the purpose of UV care, agents such as tranexamic acid that have the effect of preventing and improving spots and freckles caused by sunburn are sometimes used, so it is strongly required to improve the dispersion stability of fine-grained zinc oxide in the inner oil phase.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2004-210698

Patent Document 2: Japanese Patent Application Publication No. 2005-247722

Patent Document 3: Japanese Patent Application Publication No. 2009-209123

Patent Document 4: International Publication No. 2012/157694

Summary of the invention

Problem that the invention aims to solve

An object of the present invention is to provide an oil-in-water emulsified cosmetic composition which is excellent in dispersion stability of fine zinc oxide particles and is less likely to cause sedimentation and clogging of aggregates of the fine zinc oxide particles.

Solutions for solving problems

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, they have found that a composite powder (hereinafter referred to as "silicon dioxide-coated zinc oxide fine particles after hydrophobization") is prepared by uniformly coating zinc oxide fine particles with silicon dioxide (anhydrous silicic acid), and then treating the surface with a hydrophobization treatment agent, and then fully dispersing the hydrophobized silicon dioxide-coated zinc oxide fine particles in an oil phase component containing amino-modified silicone, and then mixing and emulsifying the obtained dispersion with an aqueous phase component and other oily components, thereby obtaining an oil-in-water emulsified cosmetic having excellent dispersion stability of zinc oxide fine particles, thereby completing the present invention.

That is, the present invention is an oil-in-water emulsified cosmetic, which comprises an aqueous phase, an oil phase dispersed in the aqueous phase, and a powder dispersed in the oil phase, wherein the oil phase comprises (A) an amino-modified silicone, and the powder is (B) hydrophobized silica-coated fine-particle zinc oxide.

Effects of the Invention

The oil-in-water emulsified cosmetic of the present invention can stably disperse fine zinc oxide in the internal oil phase by adopting the above-mentioned structure, and can suppress the sedimentation of aggregates of fine zinc oxide. In addition, since the dissolution of zinc ions from fine zinc oxide can be suppressed, the dispersion stability is not easily impaired even when used in combination with a drug such as tranexamic acid.

DETAILED DESCRIPTION

The oil-in-water emulsified cosmetic of the present invention is characterized by comprising (A) amino-modified silicone and (B) hydrophobized silica-coated fine zinc oxide particles. The components constituting the oil-in-water emulsified cosmetic of the present invention are described in detail below.

<(A) Amino-modified silicone>

As the amino-modified silicone (A) used in the present invention, a wide range of amino-modified silicones used in cosmetics can be used, and preferably a side chain amino-modified silicone having a functional group equivalent of 1 to 10000 represented by the following general formula (1). It should be noted that the "functional group equivalent" in this specification refers to the value obtained by dividing the molecular weight of the amino-modified silicone (A) by the number of amino groups contained in the molecule.

In the above general formula (1), X is an alkyl group having 1 to 18 carbon atoms, R and R' are alkyl groups having 1 to 6 carbon atoms, m is 20 to 2000, and n is 1 to 100.

(A) The functional group equivalent of the amino-modified silicone is 1 to 10,000, preferably 1,500 to 3,800. When the functional group equivalent exceeds 10,000, the dispersion becomes insufficient and the stability of the obtained emulsion tends to decrease.

Specific examples of the (A) amino-modified silicone include aminodimethylsiloxane, aminoethylaminopropyldimethylsiloxane, and aminopropyldimethylsiloxane.

The amount of the amino-modified silicone (A) is preferably 0.1 to 10% by mass, more preferably 0.2 to 5% by mass, relative to the total amount of the oil-in-water emulsified cosmetic. If the amount of the amino-modified silicone (A) is in the range of 0.1 to 10% by mass, sufficient dispersion stability can be obtained and the feel during application is also excellent.

<(B) Hydrophobized Silica-Coated Fine Particle Zinc Oxide>

The (B) hydrophobized silica-coated fine-particle zinc oxide used in the present invention is a composite powder obtained by uniformly coating fine-particle zinc oxide with silica and further treating the surface thereof with a hydrophobizing agent.

By covering the fine zinc oxide particles with silica and a hydrophobic treatment agent, the elution of zinc ions into the system is suppressed, and the reaction with drugs such as tranexamic acid can be suppressed. Therefore, even when used in combination with drugs, the powder is unlikely to aggregate, and excellent dispersion stability can be achieved.

The method of coating fine zinc oxide with silicon dioxide is not particularly limited, and conventionally known methods can be used, for example, a method of adding sodium silicate to fine zinc oxide dispersed in an aqueous solution, a method of adding alkoxysilane to fine zinc oxide dispersed in an organic solvent, etc.

As a method for hydrophobizing the silica-coated fine-particle zinc oxide using a hydrophobizing agent, for example, treatment with an organosilicon compound such as polymethylhydrogensiloxane and polymethylsiloxane; treatment with a fluorine compound such as a perfluoroalkyl phosphate and a perfluoroalcohol; treatment with an amino acid such as N-acylglutamic acid; treatment with a silane compound such as triethoxyoctylsilane; and treatment with lecithin; treatment with a metal soap; treatment with a fatty acid; treatment with an alkyl phosphate, etc. Among them, treatment with an organosilicon compound is preferred.

Examples of the organosilicon compound used in the organosilicon compound treatment include various silicone oils such as polydimethylsiloxane (or dimeticone), polymethylphenylsiloxane, polymethylhydrogensiloxane, polymethylcyclosiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trisiloxane, tetradecamethylhexasiloxane, dimethylsiloxane·methyl(polyoxyethylene)siloxane·methyl(polyoxypropylene)siloxane copolymer, dimethylsiloxane·methyl(polyoxyethylene)siloxane copolymer, dimethylsiloxane·methyl(polyoxypropylene)siloxane copolymer, dimethylsiloxane·methylcetyloxysiloxane copolymer, and dimethylsiloxane·methylstearyloxysiloxane copolymer. Polymethylhydrogensiloxane or polymethylsiloxane is preferred.

The average primary particle size of the hydrophobized silica-coated fine zinc oxide is in the range of 0.01 to 0.5 μm, preferably in the range of 0.01 to 0.25 μm. If the average primary particle size is in this range, an excellent UV protection effect can be obtained and the product can be stably formulated into the inner oil phase of an oil-in-water emulsified cosmetic.

In addition, in this specification, "average primary particle size" means the particle size at a cumulative value of 50% in a particle size distribution determined by a laser diffraction/scattering method.

The amount of the hydrophobized silica-coated fine zinc oxide is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, relative to the total amount of the oil-in-water emulsified cosmetic. If the amount of the hydrophobized silica-coated fine zinc oxide is in the range of 1 to 30% by mass, an excellent feel during application can be maintained and a sufficient UV protection effect can be obtained.

<Optional ingredients>

The oil-in-water emulsified cosmetic of the present invention may contain, in addition to the above-mentioned components (A) and (B), components commonly used in cosmetics within the range that does not hinder the effects of the present invention. For example, in addition to oil, aqueous solvent, ultraviolet absorber, surfactant, moisturizer, and drug, antioxidant, preservative, pH adjuster, chelating agent, powder, fragrance, colorant, pigment, etc. may be appropriately contained as needed.

The oil component is an oil component generally formulated in cosmetics, and examples thereof include silicone oil, hydrocarbon oil, higher alcohol, ester oil, fatty acid, grease, wax, etc. Among them, silicone oil has excellent compatibility with (A) amino-modified silicone, and can provide a smooth makeup even when used. In addition, when silicone compounds are used in the hydrophobic treatment of (B) hydrophobicized silica-coated fine zinc oxide, the dispersibility of fine zinc oxide can be significantly improved, and therefore, silicone oil is preferred.

Examples of the silicone oil include linear or cyclic polysiloxanes such as polydimethylsiloxane, polymethylphenylsiloxane, polymethylhydrogensiloxane, polydecamethylsiloxane, polydodecamethylsiloxane, polytetramethyltetrahydrogensiloxane, cyclotetramethylsiloxane, and cyclopentamethylsiloxane. When the silicone oil is added, the amount thereof is preferably 15% by mass or more, more preferably 16% by mass or more, and particularly preferably 17% by mass or more, based on the total amount of the oil-in-water emulsified cosmetic.

Examples of the hydrocarbon oil include liquid paraffin, isohexadecane, isododecane, ozokerite, squalane, squalene, pristane, paraffin, isoparaffin, ceresin, vaseline, microcrystalline wax, hydrogenated polyisobutene, and olefin oligomers.

Examples of higher alcohols include straight-chain alcohols such as lauryl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, myristyl alcohol, oleyl alcohol, and cetearyl alcohol; and branched-chain alcohols such as monostearyl glyceryl ether (baty alcohol), 2-decyltetradecyl alcohol, lanolin alcohol, cholesterol, phytosterol, hexyldodecanol, isostearyl alcohol, and octyldodecanol.

Examples of the ester oil include cetyl ethylhexanoate, isopropyl myristate, cetyl ethylhexanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyl decyl dimethyloctanoate, cetyl lactate, myristyl lactate, acetylated lanolin, isocetyl stearate, isocetyl isostearate, cholesterol 12-hydroxystearate, ethylene glycol di(2-ethylhexanoate), dipentaerythritol fatty acid ester, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glyceryl di(2-heptylundecanoate), trimethylolpropane tri(2-ethylhexanoate), ) ester, trimethylolpropane triisostearate, pentaerythritol tetraethylhexanoate, glyceryl tri(2-ethylhexanoate), cetyl alcohol 2-ethylhexanoate, 2-ethylhexyl palmitate, glyceryl trimyristate, glyceryl tri(2-heptylundecanoate), methyl ricinoleate, oleyl oleate, acetylated glycerol, 2-heptylundecyl palmitate, diisobutyl adipate, di-2-heptylundecyl adipate, ethyl laurate, di(2-ethylhexyl) sebacate, 2-hexyldecyl myristic acid, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, 2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, triethyl citrate, and the like.

Examples of the fatty acid include oleic acid, isostearic acid, linoleic acid, and linolenic acid.

Examples of the oils and fats include wood wax, cocoa butter, hydrogenated castor oil, avocado oil, camellia seed oil, macadamia nut seed oil, corn oil, olive oil, rapeseed oil, sesame oil, peach kernel oil, wheat germ oil, camellia oil, castor oil, linseed oil, safflower oil, cottonseed oil, perilla oil, soybean oil, peanut oil, tea seed oil, ginkgo oil, rice bran oil, paulownia oil, Japanese tung oil, jojoba oil, germ oil, triglycerol, tricaprylin, triisopalmitin, and the like.

Examples of the wax include carnauba wax, beeswax, candelilla wax, and jojoba wax.

Examples of the aqueous solvent include water (purified water, ion-exchanged water, tap water, etc.), lower alcohols, and mixtures thereof.

Examples of the ultraviolet absorber include octyl methoxycinnamate, octocrylene, diethylaminohydroxyhexyl benzoate, tert-butyl methoxydibenzoylmethane, ethylhexyl triazone, and bis-ethylhexyloxyphenol methoxyphenyl triazine.

Examples of the surfactant include polyoxyalkylene alkyl ethers, polyalkylene glycol fatty acid esters, POE hydrogenated castor oil derivatives, POE alkyl ethers, POE-POP alkyl ethers, PEG fatty acid esters, polyglyceryl fatty acid esters, POE glyceryl fatty acid esters, and isostearic acid PEG glyceryl esters. In addition, polyglyceryl-2 diisostearate, sorbitan sesquiisostearate, etc. can be mentioned.

Examples of the moisturizer include polyoxyalkylene-polyoxyethylene copolymer dialkyl ethers, 1,3-butylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, glycerol, diglycerol, xylitol, maltitol, maltose, and D-mannitol.

Examples of the drug include tranexamic acid, ascorbic acid (vitamin C), kojic acid, ellagic acid, arbutin, alkoxysalicylic acid, niacinamide, glycyrrhizic acid, tocopherol, and salts or derivatives thereof (e.g., sodium L-ascorbate, magnesium L-ascorbyl phosphate, L-ascorbyl glucoside, 2-O-ethyl-L-ascorbic acid, 3-O-ethyl-L-ascorbic acid, 4-methoxysalicylic acid sodium salt, 4-methoxysalicylic acid potassium salt, dipotassium glycyrrhizinate, stearyl glycyrrhizinate, tocopherol acetate, etc.).

<How to use>

The form of the oil-in-water emulsified cosmetic of the present invention is not particularly limited, and may be in any form as long as it is a cosmetic conventionally used for cosmetics such as lotion, milky lotion, cream, gel, or essence (beauty serum).

[Example]

The present invention is further described in detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, the amount of the compounding is expressed as mass % relative to the oil-in-water emulsified cosmetic. Before describing each example in detail, the evaluation method used is described.

<Dispersion stability>

The oil-in-water emulsified cosmetic (sample) was filled into 8 50 ml tubes (3 cm in diameter), and the tubes were rotated at 45 rpm for 4 hours at room temperature to perform a rolling test, and the presence or absence of powder sedimentation and clogging was visually observed.

The measurement results were evaluated according to the following criteria.

<Evaluation Criteria>

A+: No precipitation or clogging of the powder was observed in any of the eight tubes, and no powder aggregates were confirmed in the cosmetics.

A: No powder sedimentation or clogging was observed in any of the eight tubes.

B: Powder sedimentation or clogging was observed in one or more tubes.

<Example 1 to Example 12 and Comparative Example 1 to Comparative Example 8>

(B) hydrophobized silica-coated fine-particle zinc oxide was added to the oil phase component containing (A) amino-modified silicone and mixed, and the mixed solution was treated with a bead mill to fully disperse the powder to obtain a dispersion (bead diameter: 1 mmφ, bead filling rate: 50% by volume (same volume as the mixed solution), dispersion time: 60 minutes, peripheral speed: 20 m/s). Then, the obtained dispersion was mixed with the aqueous phase component and other oily components, treated with a homomixer and emulsified, thereby obtaining an oil-in-water emulsified cosmetic.

The obtained oil-in-water emulsified cosmetics were evaluated based on the above-mentioned evaluation methods and evaluation criteria. The evaluation results are also shown.

[Table 1a]

[Table 1b]

[Table 1c]

*1: Silicone KF 8004 (Shin-Etsu Chemical Co., Ltd.) *2: Silicone KF 8005S (Shin-Etsu Chemical Co., Ltd.) *3: Silicone KF 869 (Shin-Etsu Chemical Co., Ltd.)

*4: FINEX-52W-LP2 (Sakai Chemical Industry Co., Ltd.)

As shown in Table 1, regardless of which amino-modified silicone was used, the dispersion stability of the fine-particle zinc oxide coated with silica after hydrophobization with polydimethylsiloxane was excellent (Examples 1 to 6). In contrast, when other dispersants commonly used in cosmetics were used instead of amino-modified silicone, the dispersion stability was poor (Comparative Examples 1 to 7).

In addition, when fine-particle zinc oxide that was not coated with silica but was only subjected to a hydrophobic treatment was used, sufficient dispersion stability could not be obtained (Comparative Example 8).

Furthermore, from the comparison between Examples 7 and 8 and Example 9, and from the comparison between Examples 10 and 11 and Example 12, it can be seen that when silicone oil is blended, the dispersion stability is significantly improved by setting the blending amount to 15% by mass or more.

The following is an example of the formulation of the oil-in-water emulsified cosmetic of the present invention. The present invention is not limited to the following formulation examples, and can be determined by the claims. It should be noted that all the blending amounts are expressed in mass % relative to the total amount of the oil-in-water emulsified cosmetic.

Formula Example 1: Oil-in-water emulsion foundation

Claims (8)

1. An oil-in-water emulsion cosmetic comprising an aqueous phase, an oil phase dispersed in the aqueous phase, and a powder dispersed in the oil phase,

The oil phase comprises (A) amino modified organosilicon,

The powder is (B) the silica after hydrophobization is covered with fine zinc oxide.

2. The oil-in-water emulsion cosmetic according to claim 1, wherein the amount of the amino-modified silicone (a) is 0.1 to 10% by mass based on the total amount of the oil-in-water emulsion cosmetic.

3. The oil-in-water emulsion cosmetic according to claim 1, wherein (B) the silica-coated fine particle zinc oxide after hydrophobization is subjected to hydrophobization treatment with an organosilicon compound.

4. The oil-in-water emulsion cosmetic according to claim 1, wherein the average primary particle diameter of the silica-coated fine particle zinc oxide after the hydrophobization of (B) is 0.01 to 0.5 μm.

5. The oil-in-water emulsion cosmetic according to claim 1, wherein the amount of the fine particle zinc oxide covered with the silica after the hydrophobization is 1 to 30% by mass based on the total amount of the oil-in-water emulsion cosmetic.

6. The oil-in-water emulsion cosmetic according to claim 1, wherein the oil phase further comprises silicone oil.

7. The oil-in-water emulsion cosmetic according to claim 6, wherein the silicone oil is 15% by mass or more relative to the total amount of the oil-in-water emulsion cosmetic.

8. The oil-in-water emulsion cosmetic according to claim 1, further comprising tranexamic acid.