JP7173624B2 - sunscreen cosmetics - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sunscreen cosmetic comprising an emulsion containing a metal oxide, and more particularly to a sunscreen cosmetic having improved stability and feel during use.

In general, various UV care cosmetics have been developed to reduce the damage to the skin caused by ultraviolet rays (UV), and sunscreen cosmetics contain UV scattering agents and UV absorbers to protect the skin from UV rays. It is

Sunscreen cosmetics are used not only to suppress erythema due to sunburn, but also to prevent skin troubles such as spots and wrinkles caused by daily sun exposure. Sunscreen cosmetics for such applications are required to display SPF/PF-A values, and to be easy to apply and have a light texture.

For example, it is possible to display the desired SPF/PF-A values by adding a high amount of UV absorbers to sunscreen cosmetics. There is a tendency to avoid blending UV absorbers made of organic compounds.

Therefore, sunscreen cosmetics with high SPF/PF-A values (for example, sunscreen emulsified preparations) contain metal oxides such as titanium oxide, zinc oxide, and iron oxide as UV scattering agents.
Such sunscreen cosmetics are often water-in-oil (W/O) emulsified preparations in order to stably maintain the dispersed state of the metal oxide ultraviolet scattering agent.

In addition, W/O type sunscreen cosmetics have been improved in various ways so that they can be applied evenly and have as light a feeling as possible. However, W/O type emulsion preparations, which are mainly composed of oily ingredients, are not free from the oily feeling when applied due to their properties.

On the other hand, oil-in-water (O/W) emulsified sunscreen cosmetics are mainly composed of water-based ingredients, so they provide a light feeling when used. It is difficult to ensure the stability of the emulsified state because of its poor compatibility with substances, and many of them actually have low stability.

Further, there is known a technique of stabilizing the emulsified state by adding a large amount of solid components to the oil phase of emulsified cosmetics (see Patent Document 1).
However, even if such a technique is used, the emulsified cosmetic has a heavy feeling in use, and it has not been possible to obtain a cosmetic that spreads well (thinly spreads easily) upon application.

Acrylic acid-based thickeners are widely used in cosmetics because of their smooth texture. can be significantly reduced.

In order to deal with this problem, efforts were made to improve it by blending ethanol and specific surfactants. It is also necessary to deal with it without blending it (see Patent Document 2).

In addition, clay mineral-based hydrophilic thickeners are known to form a network structure called a card house structure in a state in which hydrophilic plate crystals are dispersed in water. It is used for the purpose of maintaining the state.

However, when a clay mineral-based hydrophilic thickener is used alone, syneresis occurs, and the state of the formulation changes over time. As a result, gelation and deterioration of fluidity occur, and a behavior called so-called aging may be exhibited.

In recent years, novel thickeners such as acrylic acid-based methyl taurine polymers and highly dispersible acrylic acid-alkyl methacrylate copolymers have been marketed and are widely used (see Patent Documents 3 and 4). ).

Japanese Patent No. 2749677 Japanese Patent No. 4127397 Japanese Patent No. 6600455 JP 2018-76301 A

However, with the techniques described in Patent Literatures 3 and 4, it is difficult to mix and formulate a metal oxide ultraviolet scattering agent such as titanium oxide or zinc oxide.

In addition, in order to increase the viscosity of the sunscreen cosmetic and formulate it as described above, it is necessary to incorporate a high polymer thickener. Since it is likely to cause adverse effects, it is not possible to obtain a cosmetic composition comprising an O/W emulsion that has a good feel during use.

Moreover, in recent years, there is a tendency to avoid petroleum-derived surfactants such as polyoxyethylene because safety is oriented toward sensitive skin.

Therefore, the object of the present invention is to solve the above-described problems and to provide a formulation of an O/W emulsion composition containing a large amount of metal oxides, which has excellent stability over time in the emulsified state and is an O/W emulsion. To provide a sunscreen cosmetic which has good spreadability when applied, which is peculiar to the cosmetic comprising the composition, and gives a light feeling of use without stickiness.

In order to solve the above problems, the inventors of the present application have conducted sincere research and found that a clay mineral-based hydrophilic thickener containing a metal oxide and a specific natural polysaccharide-based water-soluble thickener By blending a chain higher alcohol, polyglycerin fatty acid ester, and anionic surfactant, it spreads well when applied, and provides a light, non-sticky feel, and has excellent long-term stability. The present invention was completed by discovering that it becomes a /W type emulsion.

That is, in this invention, in order to solve the above problems, a hydrophilic compound containing 1 to 20% by mass of a metal oxide-based ultraviolet scattering agent (A), a clay mineral-based hydrophilic thickener (B), and xanthan gum (C) is provided. an oily component (D), a surfactant containing a nonionic surfactant (E) and an anionic surfactant (F), and an aqueous component (G ) as an essential component of the sunscreen cosmetic comprising an oil-in-water emulsified composition.

The sunscreen cosmetic of the present invention, which is configured as described above, contains a predetermined amount of a metal oxide-based ultraviolet scattering agent and a clay mineral-based hydrophilic thickener (B) and (C) xanthan gum in combination. By blending, there is no stickiness peculiar to natural polysaccharide-based hydrophilic thickeners, and moderate viscosity does not decrease due to long-term storage, and it is possible to achieve both the desired feeling of use and the stability of the emulsified state. .

Moreover, by using the nonionic surfactant (E) and the anionic surfactant (F) together, the emulsification stability can be reliably exhibited over the expected long period of 3 months. The anionic surfactant (F) is preferably sodium acylmethyltaurate .

In order to make a sunscreen cosmetic with a light feeling of use without stickiness due to oily ingredients without impairing the above-mentioned stability, the blending ratio of the clay mineral-based hydrophilic thickener (B) is 0.5 to 2. % by mass, and the mixing ratio of xanthan gum (C) is preferably 0.05 to 1% by mass.

For the same reason as above, it is preferable that the clay mineral-based hydrophilic thickener (B) is bentonite so that more preferable emulsification stability and feel during use can be reliably obtained.
In addition, in order to make a sunscreen cosmetic with good spreadability (extension) on the skin when applied, the oil component (D) contains more than 0.5% by mass and 5% by mass of a linear higher alcohol having 16 to 22 carbon atoms. It is preferable that it is an oily component containing the following.

In order to obtain a sunscreen cosmetic that is not sticky to the skin when applied and that does not cause poor emulsification, the nonionic surfactant (E) content is preferably 0.1 to 5% by mass. For the same reason, the nonionic surfactant (E) is preferably polyglycerin fatty acid ester. Further, for the same reason, the polyglycerol fatty acid ester preferably has a fatty acid carbon chain of 12-22 and a glycerol polymerization degree of 5-10.

The present invention provides a sunscreen cosmetic comprising an oil-in-water emulsified composition containing a predetermined amount of a metal oxide-based ultraviolet scattering agent. An O/W emulsion composition containing a large amount of metal oxides sufficient for ultraviolet protection has excellent stability over time and provides a light feeling of use peculiar to the O/W emulsion composition. It has the advantage of being a cosmetic.

A sunscreen cosmetic according to an embodiment of the present invention is an O/W emulsion containing a metal oxide, and contains xanthan gum as a clay mineral-based hydrophilic thickener and a natural polysaccharide-based hydrophilic thickener. Contains higher alcohol, polyglycerin fatty acid ester, and anionic surfactant as essential ingredients.

As the metal oxide-based ultraviolet scattering agent (A) used in the present invention, metal oxides such as titanium oxide, zinc oxide, iron oxide, and cerium oxide, which are well known as ultraviolet scattering agents used in cosmetics, can be selectively used. In some cases, they are blended for the purpose of adjusting the color tone of the composition, adjusting the skin tone, concealing the skin, etc., in addition to UV protection.

In particular, titanium oxide and zinc oxide are components that are safe and highly effective as UV scattering agents, and these metal oxides can be used alone or in any combination of two or more.

If the mixing ratio of the metal oxide-based ultraviolet scattering agent (A) is 1 to 20% by mass in the sunscreen cosmetic, the desired ultraviolet protection can be obtained for preventing the desired skin troubles, but it is higher. A preferable blending ratio for obtaining ultraviolet protection is 5 to 20% by mass, more preferably 10 to 20% by mass, furthermore 15 to 20% by mass.
The metal oxide-based ultraviolet scattering agent (A) can be easily mixed and more uniformly dispersed if it is dispersed in an oil agent in advance and blended in the cosmetic.

The clay mineral-based hydrophilic thickener (B) used in the present invention is a clay mineral called smectite, which has a layered crystal structure. Water molecules are adsorbed between crystal layers in water, and each layer exfoliates to form a network. and has the ability to thicken water. However, smectite that does not have chemical reactivity with the metal oxide-based ultraviolet scattering agent (A) is preferred.

Examples of smectites include hectorite, montmorillolite, sapolite, and beidellite, all of which function to thicken water as described above.
For example, smectite, which is a hydrophilic plate-like crystal particle and forms a network structure called a card house structure by electrostatically bonding the crystal surface and the crystal edge in a dispersed aqueous system, is preferable. For example, montmorillonite is the main component. It is desirable to employ a bentonite of .sup.2 in order to thicken the aqueous component by such a mechanism.

On the other hand, as an unfavorable example, sodium magnesium silicate, which is a hydrophilic thickener but is not mineral but is a synthetic silicate, forms a complex with a metal oxide and increases viscosity. However, the gel-like particles are large enough to be visible, resulting in insufficient swelling.

Similarly, magnesium aluminum silicate, which is a synthetic silicate, can be used to prepare an emulsified composition with good spreadability, but is not preferable because it deteriorates storage stability at high temperatures.

In addition, when an acrylic acid-based methyl taurine polymer or an acrylic acid-alkyl methacrylate copolymer is used instead of bentonite, etc., it may cause poor stability or aggregation due to elution of metal oxides into the aqueous phase. I don't like it because there is

The mixing ratio of the clay mineral-based hydrophilic thickener (B) is preferably 0.5 to 2% by mass, more preferably 0.8 to 1.7% by mass. In a system that does not contain the clay mineral-based hydrophilic thickener (B), the thixotropy of the liquid is lowered, and if the content is less than 0.5% by mass, it becomes difficult to ensure stability. In addition, if the content exceeds 2% by mass, powdery deposits are generated when the liquid is applied to the skin, which is not preferable.

In addition, xanthan gum (C), which is a natural polysaccharide-based water-soluble thickener, is preferable as a hydrophilic thickener, and its blending amount is preferably 0.05 to 1% by mass, more preferably 0.1 to 0.8. % by mass is more preferred. If the amount is less than 0.05% by mass, it will be difficult to ensure stability, and if it exceeds 1% by mass, the cosmetic will have a sticky and heavy feeling when used, which is peculiar to xanthan gum.

Xanthan gum (C) is preferred over other natural polysaccharide-based water-soluble thickeners. It is less preferable than xanthan gum because it is less stable than xanthan gum, and its stability tends to decrease due to changes in liquid properties at high temperatures, and changes in state, such as vomiting, are likely to occur. Similarly, sodium alginate is not preferable because it tends to gel with inorganic substances such as bentonite and metal oxides.

The oily component (D) blended as an emulsifying aid is preferably an oily component containing a linear higher alcohol having 16 to 22 carbon atoms, and the blending amount is more than 0.5% by mass and 5% by mass or less. is preferable, 1 to 5% by mass is more preferable, and 2 to 4% by mass is more preferable.

When the blending amount is less than 1% by mass, in which substantially no oily component is contained, it is difficult to ensure emulsion stability. Although it can be prepared as a moisturizing cream, it is not preferable because it does not spread well when applied.

In addition, the oily component (D) is a component that constitutes the oil phase of the emulsified composition. In order to obtain an O/W type emulsified composition with high sensitivity, it is preferable to include a higher alcohol (monohydric alcohol having 8 or more carbon atoms), and in particular, cetanol and stearyl alcohol as linear higher alcohols having 16 to 22 carbon atoms. , arachidyl alcohol, behenyl alcohol, and vegetable higher alcohol such as hydrogenated rapeseed oil alcohol obtained as a mixture thereof.

As the nonionic surfactant (E), a well-known one can be adopted, but it is preferable to adopt, for example, polyglycerin fatty acid ester, etc., and the blending amount is preferably 0.1 to 5% by mass. Furthermore, 0.5 to 4% by mass is more desirable. If the amount is less than 0.1% by mass, poor emulsification will occur, and if it exceeds 5% by mass, stickiness peculiar to polyglycerin fatty acid ester will appear.

Polyglycerol fatty acid esters include polyglyceryl laurate, polyglyceryl dilaurate, polyglyceryl trilaurate, polyglyceryl tetralaurate, polyglyceryl myristate, polyglyceryl dimyristate, polyglyceryl trimyristate, polyglyceryl pentamystate, polyglyceryl palmitate, and polyglyceryl dipalmitate. , polyglyceryl isopalmitate, polyglyceryl stearate, polyglyceryl distearate, polyglyceryl tristearate, polyglyceryl isostearate, polyglyceryl diisostearate, polyglyceryl triisostearate, polyglyceryl tetraisostearate, polyglyceryl oleate, polyglyceryl dioleate, polyglyceryl trioleate, Polyglyceryl tetraoleate, polyglyceryl behenate, polyglyceryl tribehenate, polyglyceryl tetrabehenate and the like can be mentioned, and one or more of these can be used.

As the anionic surfactant (F), a well-known one can be used, but sodium acylmethyltaurate is preferably used. A sunscreen cosmetic composed of an emulsified composition containing only a nonionic surfactant (E) and not containing an anionic surfactant (F) does not have good storage stability. In particular, when the sucrose fatty acid ester of the nonionic surfactant (E) is used alone, sufficient emulsion stability cannot be obtained.

In addition, the composition of the present invention may contain various additive components that are commonly used in cosmetics, as long as they do not impair the effects of the present invention. Examples of additive components include humectants, ultraviolet absorbers, higher alcohols, sequestering agents, film-forming agents, sugars, amino acids, vitamins, antioxidants, pigments, and fragrances.

The sunscreen cosmetics of the examples and comparative examples described below were dissolved by mixing, heating and stirring the water-soluble components at a temperature of about 70° C. in the mixing ratios shown in Tables 1 to 6 below. The aqueous phase and the oil phase, which is obtained by dissolving the oil-soluble components under the same conditions of about 70° C. and then dispersing the metal oxide-based UV scattering agent, are blended, and the oil phase is refined with a homomixer. The mixture was allowed to emulsify, and then cooled to produce a cream.
The obtained sunscreen cosmetics of Examples and Comparative Examples were evaluated by the following evaluation methods, and the evaluation results are shown in Tables 1-6.

(Evaluation method: storage stability)
Each sample was filled in a 70 mL glass mayonnaise bottle and stored in a constant temperature bath at 40° C. for a predetermined period, and storage stability was evaluated based on the period.
[Evaluation] [Judgment]
No change until 3 months: ○
Changed at 1 month: △
Cannot be prepared: ×

(Evaluation method: feeling of use)
20 evaluation panelists (10 adult males and females in their 20s to 40s) evaluated the feeling of use (elongation, stickiness, etc.) when applied to the skin on a 5-point scale according to the following criteria, and further evaluated from the average score. .

[evaluation]
5 points: Very good.
4 points: Good.
3 points: Normal.
2 points: Bad.
1 point: very bad.

[judgement]
◎: Average score 3.5 points or more ○: Average score 2 points or more, less than 3.5 points △: Average score less than 2 points ×: Not implemented because it cannot be prepared

[Examples 1 to 3, Comparative Example 1]
As is clear from the results shown in Table 1, in Examples 1 to 3 in which bentonite containing montmorillonite as the main component was used as the clay mineral-based hydrophilic thickener (B), both stability and usability were achieved. A sunscreen cosmetic (preparation) was obtained, and it was particularly good when the blending amount was 0.5% by mass or more and 2% by mass or less.

On the other hand, in Comparative Example 1, since the clay mineral-based hydrophilic thickener (B) was not blended, a creamy formulation could not be prepared.
When a relatively large amount of the clay mineral-based hydrophilic thickener (B) was blended, preparation in the dispersing and dissolving steps was difficult, and work efficiency decreased, resulting in a highly viscous creamy preparation. It was possible.

[Comparative Examples 2 , 3, 5]
As is clear from the results shown in Table 2, comparative examples in which a synthetic silicate or an acrylic acid-based polymer or copolymer was blended as a thickener instead of the bentonite of the clay mineral-based hydrophilic thickener (B). 2 , 3 and 5 failed to achieve a good balance between stability and usability.
Comparative Example 2 using sodium magnesium silicate (B') formed a complex with a metal oxide and did not exhibit the desired viscosity. A gel-like insoluble matter was confirmed. In Comparative Example 3, the viscosity was extremely low and stability was not obtained.

In addition, in Comparative Example 5 using the acrylic acid-alkyl methacrylate copolymer (B'') as a thickener, white agglomerates of metal oxides were confirmed, and it was a preferable cosmetic immediately after preparation. I didn't.

[Examples 4 to 6, Reference Example 1 , Comparative Example 6]
As is clear from the results shown in Tables 3 and 1 above, the amount of xanthan gum (C), which is a hydrophilic thickener, is sufficient even in Example 2 (see Table 1), where the content is 0.1% by mass. Since good stability and feeling of use were obtained, compared to 0% Comparative Example 6, even a small amount of, for example, 0.05% by mass is considerably effective, and Examples 4 and 5 It is more preferable that 0.4% by mass or more is blended in.
In addition, the amount of xanthan gum may be increased as long as it does not impede the feeling of use, but from the results of Example 6 and Reference Example 1 , it is preferable that the amount of xanthan gum is 1% by mass or less, and stability and feeling of use are obtained. It can be seen that they are fully compatible. Reference Example 1 required a relatively long time or a strong mechanical force for the dissolution process due to its viscous liquidity.

[Comparative Examples 7 to 12]
In Comparative Examples 7 to 11 shown in Table 4 above, tamarind gum, cellulose and its derivative hydroxyethyl cellulose, locust bean gum, carrageenan, and guar gum were blended as natural polysaccharide-based hydrophilic thickeners other than xanthan gum. , The viscosity immediately after preparation was lower than that of xanthan gum, and furthermore, the stability was remarkably lowered due to changes in liquid properties at high temperatures. In either case, gelation with inorganic substances such as metal oxides and metal oxides was observed, and no preferable preparations were obtained.
On the other hand, as is clear from the evaluation described in Table 1 above, Examples 1 to 3, in which xanthan gum (C) was blended as a natural polysaccharide-based hydrophilic thickener, are formulations that are both stable and comfortable to use. was gotten.

[Examples 8-9, Reference Example 2, Examples 11-12 , Comparative Example 13]
As is clear from the results shown in Table 5, among the oily components (D) blended as emulsifying aids, predetermined higher alcohols such as cetanol and hydrogenated rapeseed oil alcohol (linear In Example 8, in which the total amount of higher alcohol) was 1% by mass or more, and in Example 9, in which the total amount was 5% by mass or less, formulations with both stability and usability were obtained.
If the amount of the higher alcohol included in the oily component (D) is 0.5% by mass or less, the viscosity will be low and the stability will be considerably reduced. In Reference Example 2 , in which the predetermined higher alcohol content in the oily component (D) exceeded 5% by mass, the cream was hard and creamy, but had good stability.

In addition, for polyglycerol fatty acid ester, which is a nonionic surfactant (E), those with different fatty acids such as polyglyceryl myristate-10 (Example 11) and polyglyceryl stearate-10 (Example 12) were used. However, a formulation having both stability and usability was obtained.

On the other hand, separation was confirmed in Comparative Example 13 in which the anionic surfactant (F) was not used, and the expected cosmetic could not be prepared.

[Example 13]
As is clear from the results shown in Table 6, Example 13 in which titanium oxide was blended as a metal oxide was as good as Example 2 (see Table 1) and Example 5 (see Table 3) in which zinc oxide was blended. Similarly, it was a cream-like preparation with excellent stability and good feeling during use.

[Example 14, Comparative Example 14]
In addition, if the amount of the metal oxide-based ultraviolet scattering agent (A) was increased and it was 20% by mass or less as in Example 14, it was possible to prepare a cream-like formulation that was excellent in stability and usability. At 24% by mass as in Example 14, it was difficult to ensure stability.

[Example 15]
In addition, from the results of Example 15 and Comparative Example 14, it was found that if the water (G) content is 40% by mass or more, there is a fresh feeling during use.

[Example 16]
Example 16 can be expected to have an action of a medicinal ingredient that improves antioxidant properties, moisturizing, skin tension, etc., and is used as an oil-in-water emulsified cosmetic with good spreadability, as in the other examples. The feel and stability were good.
From these facts, it can be seen that each example exhibits the expected excellent effect as a sunscreen cosmetic.

[Example 17]
In Example 17, the total amount of the nonionic surfactant (E) blended was within 5% by mass, and the feeling of use was good. seemed to increase.

Claims (4)

A hydrophilic thickener containing 5 to 20% by mass of a metal oxide-based ultraviolet scattering agent (A), 0.05 to 1% by mass of a clay mineral-based hydrophilic thickener (B) and xanthan gum (C), and cetanol , stearyl alcohol, arachidyl alcohol, behenyl alcohol, and hydrogenated rapeseed oil alcohol . A surfactant containing a nonionic surfactant (E) that is a polyglycerin fatty acid ester and an anionic surfactant (F) that is sodium acylmethyltaurate, and an aqueous component (G) containing 40% by mass or more of water A sunscreen cosmetic comprising an oil-in-water emulsified composition comprising 2. The sunscreen cosmetic according to claim 1, wherein the mixing ratio of the clay mineral-based hydrophilic thickener (B) is 0.5 to 2% by mass. 3. The sunscreen cosmetic according to claim 1, wherein the clay mineral-based hydrophilic thickener (B) is bentonite. The sunscreen cosmetic according to any one of claims 1 to 3, wherein the nonionic surfactant (E) is contained in an amount of 0.1 to 5% by mass.