JP2022128378A - whitening cosmetics - Google Patents

Abstract

To provide a skin-whitening cosmetic that allows the promotion of collagen production, which is one of skin-whitening requirements, in a manner that causes an active ingredient to be absorbed through the skin.SOLUTION: A skin-whitening cosmetic contains, as an active ingredient, a hydrotalcite that is represented by the formula (1) (where M2+ is at least one divalent metal, M3+ is at least one trivalent metal, An- is an n-valent anion primarily composed of glycine, and x and m satisfy 0.1<x<0.4 and 0<m) and shows delamination in a water medium.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to novel whitening cosmetics. More particularly, it relates to a whitening cosmetic containing as an active ingredient a hydrotalcite that delaminates in water and contains glycine as a main component as an intercalary anion.

Whitening is one of the important demands of women. It is believed that the following three elements are necessary to achieve whitening.
(1) Suppresses the production of melanin, which causes spots and freckles.
Since melanin pigment increases when exposed to ultraviolet rays, UV absorbers should be used on a daily basis to protect against the effects of arbutin, vitamin C and its derivatives, tranexamic acid, 4-methoxysalicylic acid, vitamin E, which have the effect of reducing melanin pigment. Countermeasures such as prescribing reducing agents such as hydroquinone in cosmetics have been taken.
(2) Moisturizing.
When the skin is dry, the texture becomes rough and the reflectance of light decreases. As a result, the transparency of the skin is lost, giving a dull impression. In a well-moisturized state, the skin becomes transparent. Water retention agents such as glycerin, amino acids and hyaluronic acid, and oil film agents such as waxes and fatty acids are used.
(3) Prevent the decrease of collagen in the dermis layer.
Collagen provides the skin with firmness and elasticity. Collagen is a polymer of amino acids, so it cannot be absorbed through the skin. Therefore, it can only be ingested through meals, but is decomposed into amino acids or trimers thereof. There is no choice but to take a lot of protein, but its effect is limited.

（式中、Ｍ^２＋はＭｇ，Ｆｅ，Ｃｏ，Ｎｉ，Ｍｎ，Ｃｕ，Ｚｎ等の２価金属、Ｍ^３＋はＡｌ，Ｆｅ，Ｃｒ，Ｃｏ，Ｌａ等の３価金属、Ａ^ｎ－はＣｌ^－，ＮＯ_３ ^－，ＣＯ_３ ^２－等のｎ（ｎは整数）価の層間アニオンを示し、ｘとｍは０＜ｘ＜０．５，０＜ｍ，の範囲にある）で表されるハイドロタルサイト類は、２価金属水酸化物に３価金属が固溶しプラスに荷電した基本層と、基本層のプラス荷電を中和するアニオン（層間アニオン）と結晶水（層間水）からなる中間層から構成されている層状構造化合物である。基本層を中間層から切り離す、所謂層間剥離が特定のアニオンと溶媒の選択で起こることが判っている。例えば層間アニオンとしてグリシン、溶媒としてホルムアミドの組み合わせ（非特許文献１）、層間アニオンとして芳香族アミノカルボン酸、溶媒としてアルコール又は水との組み合わせ（特許文献１）、層間アニオンとしてアラニン、ロイシン、セリン、リシン、ヒスチジン、溶媒としてホルムアミドとの組み合わせ（特許文献２）、層間アニオンとしてフェノキシ酢酸マグネシウム、溶媒としてアルコールとの組み合わせ（特許文献３）等の方法がある。Formula (2) below

(In the formula, M ²⁺ is a bivalent metal such as Mg, Fe, Co, Ni, Mn, Cu, Zn, M ³⁺ is a trivalent metal such as Al, Fe, Cr, Co, La, ^An- is Cl ⁻ , NO ₃ ⁻ , CO ₃ ^2- , etc. (where n is an integer), where x and m are in the range of 0<x<0.5, 0<m). Talcites consist of a positively charged base layer in which a trivalent metal is solid-dissolved in a divalent metal hydroxide, an anion (interlayer anion) that neutralizes the positive charge of the base layer, and water of crystallization (interlayer water). It is a layered structure compound composed of an intermediate layer. It has been found that so-called delamination, which separates the base layer from the intermediate layer, occurs with the choice of specific anions and solvents. For example, a combination of glycine as an interlayer anion and formamide as a solvent (Non-Patent Document 1), a combination of an aromatic aminocarboxylic acid as an interlayer anion and alcohol or water as a solvent (Patent Document 1), alanine, leucine, serine as an interlayer anion, Examples include a combination of lysine, histidine, and formamide as a solvent (Patent Document 2), and a combination of magnesium phenoxyacetate as an interlayer anion and alcohol as a solvent (Patent Document 3).

In Non-Patent Document 1, hydrotalcites synthesized by a coprecipitation method are used, and glycine is used as an interlayer anion, but delamination cannot be performed with water. The reason is that glycine accounts for about 20 mol%, _NO3 about 30 mol%, and _CO3 about 50 mol% in the total intercalation anions, and glycine is not the main component. It is well known that carbonate-type and nitrate-type hydrotalcites have strong bonding strength with the base layer and cannot be delaminated.

T. Hibino and W.; Jones (2000 Journal of Materials Chemistry, Vol. 11, pp. 1321-1323)

Japanese Patent Application Laid-Open No. 2004-189671 JP-A-2005-89269 W2006/068118

Collagen, which is an important requirement for skin whitening, is a macromolecule of amino acids, so it cannot be obtained by absorption through the skin. Even if you eat collagen, it will be digested in the body and broken down into amino acids. Therefore, it is necessary to ingest a diet rich in amino acids. In addition, it is said that minerals and vitamin C are necessary for converting amino acids into collagen (polycondensation). Therefore, conventional dietary intake of collagen is inefficient. Therefore, there is a strong demand for collagen supplementation that can be absorbed through the skin.

（式中、Ｍ^２＋は２価金属の少なくとも１種以上、好ましくはＭｇおよび／またはＺｎを示し、Ｍ^３＋は３価金属の少なくとも１種以上、好ましくはＡｌを示し、Ａ^ｎ－はグリシンを主成分（少なくとも５０％以上）とするｎ価のアニオン、をそれぞれ示し、ｘおよびｍはそれぞれ０＜ｘ＜０．４，０＜ｍの範囲にある）で表され、水媒体中で層間剥離したハイドロタルサイト類を皮膚に塗布する方法が美白に有効であることを発見した。本発明者は、コラーゲンがグリシンを必須成分とする３種のアミノ酸の３量体を繰り返し単位とする高分子であることに注目した。コラーゲンの主成分であるグリシンを皮膚から吸収されやすい状態にすれば、コラーゲンができる真皮層まで効率よく供給できるはずであるとの考えに基づいている。皮膚から吸収され易い状態のグリシンにするために、マイナスに荷電している皮膚を透過し易いプラスに荷電しているハイドロタルサイト類の層間にグリシンを組み込み、且つ水媒体中で層間剥離させ約１ｎｍの厚さに分散させる。以上の考えに基づき、従来困難であった層間アニオンの主成分がグリシンであるハイドロタルサイト類の新合成法を開発し、水媒体中での層間剥離を可能にした。新合成法は、ハイドロタルサイト類を焼成し酸化物にした後に、グリシン水溶液中で水和反応させ、ハイドロタルサイト類の構造を再構築する方法である。As a result of intensive research to solve the above problems, the present invention has the following formula (1)

(In the formula, M ²⁺ represents at least one or more divalent metals, preferably Mg and/or Zn, M ³⁺ represents at least one or more trivalent metals, preferably Al, and A ^n- represents glycine. n-valent anion, which is the main component (at least 50% or more), respectively, and x and m are each in the range of 0<x<0.4, 0<m), delaminating in an aqueous medium We discovered that the method of applying hydrotalcites to the skin is effective for whitening. The present inventors have noted that collagen is a polymer having repeating units of trimers of three kinds of amino acids with glycine as an essential component. It is based on the idea that glycine, which is the main component of collagen, should be efficiently supplied to the dermis layer where collagen is produced if glycine is easily absorbed from the skin. In order to obtain glycine in a state that is easily absorbed through the skin, glycine is incorporated between the layers of negatively charged hydrotalcites that are easily permeable through the skin and are positively charged. Disperse to a thickness of 1 nm. Based on the above idea, we developed a new synthesis method for hydrotalcites whose main component of the intercalation anion is glycine, which was previously difficult, and enabled delamination in an aqueous medium. The new synthetic method is a method of restructuring the structure of hydrotalcites by calcining hydrotalcites into oxides and then hydrating them in an aqueous glycine solution.

It contains a large amount of glycine, has a high transparency, and can be used as a gel-like product with a dry feel (because it is an aqueous medium, and almost all cosmetics contain an organic solvent, so there is a sticky feeling). Since hydrotalcite adsorbs and retains water, it also has a moisturizing effect. The moisturizing effect can be enhanced by simply adding a conventionally known moisturizing agent, such as an aqueous solution of glycerin, amino acid, or the like. Furthermore, an aqueous solution of vitamin C and its derivatives and a mineral monocarboxylate can be contained between the hydrotalcites layers instead of water of crystallization. These agents are thought to contribute not only to the production of collagen but also to the suppression of melanin production. It can also be used for purposes other than cosmetics, for example, as an antirust agent for antirust paints.

Photograph of sample holder for XRD measurement in Example 1 XRD of hydrated reactant of Example 1 Skin application test results of Example 3

（式中、Ｍ^２＋は２価金属の少なくとも１種以上、好ましくはＭｇおよび／またはＺｎを示し、Ｍ^３＋は３価金属の少なくとも１種以上、好ましくはＡｌを示し、Ａ^ｎ－はグリシンを主成分とするｎ価のアニオンをそれぞれ示し、ｘおよびｍはそれぞれ０＜ｘ＜０．４、好ましくは０．１＜ｘ＜０．４、特に好ましくは０．２≦ｘ≦０．３５，０＜ｍの範囲にある）で表され、水媒体中で層間剥離するハイドロタルサイト類をゲル状皮膚塗布型美白化粧料として使用できる。層間アニオンＡ^ｎ－はグリシンを主成分としながら、その１部を、酸性アミノ酸（グルタミン酸及びアスパラギン酸）を含む他のアミノ酸で置換することが出来る。酸性アミノ酸はアルカリ性であるハイドロタルサイト類のｐＨ低下の調整に、アミノ酸全体は保湿性の強化に寄与する。さらに、ビタミンＣでも置換でき、ビタミンＣのメラニン抑制効果及びコラーゲン合成の補酵素としての作用を付加できる。The present invention uses the following formula (1)

(In the formula, M ²⁺ represents at least one or more divalent metals, preferably Mg and/or Zn, M ³⁺ represents at least one or more trivalent metals, preferably Al, and A ^n- represents glycine. Each represents an n-valent anion as a main component, and x and m are each 0<x<0.4, preferably 0.1<x<0.4, particularly preferably 0.2≤x≤0.35, In the range of 0<m), hydrotalcites that undergo delamination in an aqueous medium can be used as gel-like skin-applied whitening cosmetics. The interlayer anion ^An- is based on glycine, part of which can be replaced with other amino acids, including acidic amino acids (glutamic acid and aspartic acid). Acidic amino acids contribute to the adjustment of pH reduction of alkaline hydrotalcites, and amino acids as a whole contribute to enhancement of moisturizing properties. Furthermore, it can be replaced with vitamin C, and the melanin suppressing effect of vitamin C and the action as a coenzyme for collagen synthesis can be added.

Interlayer water in formula (1) can be replaced with any substance having polarity. Therefore, moisturizing agents such as glycerin, 3-butylene glycol, glucose, hyaluronic acid, sodium ascorbyl phosphate, magnesium ascorbyl phosphate, ascorbyl glucoside, ethyl ascorbate, ascorbate-2-phosphate-6-palmitate, Vitamin C derivatives such as glyceryl octylascorbic acid can be substituted. As a result, the former can add a moisturizing effect, and the latter can add a melanin suppressing effect. Furthermore, minerals are supplemented with monocarboxylic acid salts of essential minerals such as Ca, Mg, Fe, Zn, Mn and Cu, promoting collagen synthesis and normalizing melanin turnover.

The width of the primary particles (single crystal) of the hydrotalcites of formula (1) is in the range of 0.01 μm to 5 μm, and the thickness after delamination is about 1 nm. When the delaminated product of the present invention is applied to the skin, the width direction of the primary particles and the surface of the skin are almost parallel to each other, thereby imparting slipperiness. This slipperiness tends to improve as the width of the primary particles increases.

[Production method]
The hydrotalcites represented by the formula (1) of the present invention, which exfoliate in an aqueous medium, are produced by calcining the hydrotalcites represented by the formula (2) at 300° C. to 800° C. to form oxides. Afterwards, this oxide can be added to water in which glycine is dissolved and hydrated. The hydration reaction is preferably heated at 40-100° C. for 0.5-2 hours with stirring. The amount of glycine to be added is preferably 1 mol or more, particularly preferably 1.5 mol to 2.5 mol, per 1 mol of the trivalent metal in the oxide. In this hydration reaction, part of the water can be replaced with an alcohol such as ethanol. In addition, moisturizing agents such as glycerin, amino acids, ethylene glycol, propylene glycol, urea, melanin inhibitors and collagen synthesis coenzymes such as vitamin C and vitamin C derivatives, and substances such as Ca, Mg, Zn, Fe, Mn, and Cu. Carboxylate can be added and contained as an essential mineral. In addition to these, water-soluble components can be added. However, since polyvalent anions having a valence of 2 or more inhibit delamination, it is preferable to minimize their addition.

[Method for producing hydrotalcites before firing]
The hydrotalcites represented by formula (2) are produced by preparing a mixed aqueous solution of water-soluble divalent metal salts and trivalent metal salts, such as chlorides, nitrates, and acetates of Mg, Zn, and Al, and water. It can be produced by coprecipitating with an alkali such as sodium oxide or sodium carbonate while maintaining the pH at about 7 or more. After the coprecipitation reaction, the interlayer anions can be converted by other anions by ion exchange methods. Since the width of the primary particles obtained by the coprecipitation reaction is mostly 0.1 μm or less, hydrothermal treatment is performed when the primary particles are to be made larger than this. Hydrothermal treatment is preferably carried out at 120 to 250° C., particularly preferably 150 to 250° C., for 1 hour or more, preferably 5 hours or more, and particularly preferably 10 hours or more. The width of the primary particles can be increased in the range of 0.2 to 5 μm by hydrothermal treatment.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

1 L of mixed aqueous solution of magnesium chloride and aluminum chloride (Mg = 1.0 mol/L, Al = 0.4 mol/L, about 30°C) and 100 mL each of sodium hydroxide aqueous solution (4 mol/L, about 30°C) /min, at a flow rate of about 70 mL/min, into a container with a capacity of 3 L in which 500 mL of water was previously added, while stirring, with a metering pump to coprecipitate while maintaining the pH at 9.4 to 9.7. The coprecipitate was filtered under reduced pressure, ion-exchanged with 1 L of 0.4 mol/L sodium carbonate aqueous solution (about 30° C.), and then washed with 1 L of water. After water was added to the washed material and dispersed with a homogenizer, about half of the washed material was placed in a 1-liter autoclave and hydrothermally treated at 140° C. for 10 hours. As a result of measuring the width of the primary particles by SEM, it was about 0.4 μm on average. After the hydrothermally treated slurry was filtered, dried, and sieved through a 100-mesh filter, it was placed in a siliconenit furnace and calcined at 600° C. for 4 hours. XRD of the sieved powder showed a diffraction pattern similar to that of hydrotalcite.

Although the XRD of the fired product is slightly shifted to the high angle side, it shows a diffraction pattern similar to that of magnesium oxide, indicating that Al is dissolved in MgO. 17 g of reagent grade 1 glycine and 600 mL of deionized water are placed in a 1 L beaker and dissolved, heated to about 70° C., 20 g of the baked product is added with stirring, and hydrated at 85° C. to 90° C. for about 40 minutes. reacted. After a few minutes, gelation rapidly occurred, and the hydrated reaction product became a transparent gel. FIG. 1 shows a photograph of this gel and a sample holder for XRD measurement filled with hydrotalcite before firing. Through the glass backing of this gel-filled sample holder, the letters on the underlying print are clearly visible. On the other hand, hydrotalcites (interlayer anions are carbonate ions) before firing are opaque, and characters on printed matter placed underneath cannot be seen at all. FIG. 2 shows the XRD measurement results of this gel and after drying this gel at 90° C. for 5 hours. XRD of this gel shows no diffraction peaks, indicating delamination. The dried product of this gel shows a diffraction pattern similar to that of hydrotalcite, and it can be seen that the delamination is disappearing together with the decrease in transparency. CO ₂ was analyzed by the AGK carbon dioxide measurement method using the dried product at 90° C. for 5 hours. The same dried product was dissolved in hydrochloric acid, and Mg and Al were determined by chelate titration. Based on the above analysis results, the results of examining the composition are as follows.
[ _Mg0.72Al0.28 (OH) ₂ ][(glycine) _{0.22 ( CO3} ) _0.03 ( _H2O ) _m ]
(However, the amount of glycine is the theoretical value obtained by subtracting the double number of moles of _CO3 from the number of moles of Al, and m is a real number of 0 or more.)

1 L of mixed aqueous solution of zinc nitrate, magnesium nitrate and aluminum nitrate (Zn = 0.4 mol/L, Mg = 0.8 mol/L, Al = 0.4 mol/L, 30°C) and sodium hydroxide aqueous solution (4 .0 mol/L, 30° C.) at a flow rate of 100 mL/min and about 80 mL/min, respectively, into a vessel with a capacity of 3 L containing 500 mL of water in advance, with a metering pump, while the pH is adjusted to about 8.0 mol/L. Coprecipitation was carried out while maintaining at 9 to 9.2. After that, in the same manner as in Example 1, ion exchange, washing with water, dispersion treatment in water, and hydrothermal treatment at 120° C. for 10 hours were performed. The hydrothermally treated product was filtered, dried, sieved (100 mesh), and then calcined at 600° C. for 3 hours. XRD of the sievate showed a diffraction pattern similar to that of hydrotalcite. The average of primary particles measured by SEM was 0.2 μm.

30 g of the baked product was added with stirring to 700 mL of hot water (60° C.) in which 15 g of glycine was dissolved, and hydrated for 1 hour. After a few minutes, it gelled and became transparent. XRD of this gel showed no diffraction peaks, indicating delamination. After drying this gel at 90° C. for 5 hours, the composition was analyzed in the same manner as in Example 1. The results are shown below.
[ _{Mg0.52Zn0.25Al0.23} ( _OH ) ₂ ][(glycine) _0.15 ( _CO3 ) _0.04 ( _H2O ) _m ]
(However, the amount of glycine was obtained in the same manner as in Example 1. m is a real number of 0 or more.)

[Whitening effect test]
The highly transparent gel (0.5 to 0.7 g) obtained in Example 1 was given to 3 people (1 woman in her 30s, 1 woman in her 40s, and 1 man in her 60s) once a day on one side. It was applied to the back of the hand, and after one month, the whiteness of the skin surface was visually observed, and the difference in smoothness was compared by touch. All three subjects had better skin whiteness and smoothness when the transparent gel of the present invention was applied. Fig. 3 (photograph) shows the difference between both hands of a man in his 60s after continuous application for 6 months. The application of the product of the present invention resulted in not only whiteness but also fewer wrinkles, which is considered to be due to an increase in collagen in the dermis layer.

Claims (7)

Formula (1) below

(Wherein, M ²⁺ is at least one divalent metal, M ³⁺ is at least one trivalent metal, A ^n- is an n-valent anion composed mainly of glycine, x and m are in the ranges of 0.1<x<0.4 and 0<m, respectively), and contains hydrotalcite as an active ingredient that delaminates in an aqueous medium. 2. The whitening cosmetic according to claim 1, wherein in formula (1), part of A ^n- is an acidic amino acid such as glutamic acid or aspartic acid, and pH is 6-8. 3. The whitening cosmetic according to claim 1, wherein M ²⁺ and M ³⁺ in formula (1) are Mg and/or Zn and Al, respectively. 4. The whitening cosmetic composition according to any one of claims 1 to 3, wherein part of the inter-layer water in formula (1) is replaced with at least one vitamin C derivative. The whitening cosmetic composition according to any one of claims 1 to 4, wherein a part of A ^n- in formula (1) is ascorbic acid. 6. The whitening cosmetic composition according to any one of claims 1 to 5, wherein part of the inter-layer water in formula (1) is replaced with at least one of glycerin, ethylene glycol, propylene glycol and hyaluronic acid. Claims 1-, wherein a part of the inter-layer water in the formula (1) is replaced with a monocarboxylate of at least one essential mineral selected from Ca, Mg, Zn, Fe, Mn, and Cu. 6. The whitening cosmetic according to 6.

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