Whitening cosmetic

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

[0001] The present invention relates to a novel whitening cosmetic. More specifically, it relates to a whitening cosmetic containing hydrotalcites in which the interlayer anion contains glycine as a main component and exfoliates in water as an active ingredient.

Background Art

[0002] Whitening is one of the important desires of women. To achieve whitening, the following three elements are considered necessary. (1) Suppress the production of melanin, which is the cause of freckles and spots. When exposed to ultraviolet rays, the amount of melanin pigment increases. Therefore, ultraviolet absorbers are used daily for protection, and at the same time, reducing agents such as arbutin, vitamin C and its derivatives, tranexamic acid, 4-methoxysalicylic acid, vitamin E, and hydroquinone, which have the effect of reducing melanin pigment, are formulated in cosmetics. (2) Moisturize. When the skin is dry, the texture becomes rough and the light reflectance decreases. As a result, the transparency of the skin is lost, giving a dull impression. When moisturization is good, the skin shows transparency. Humectants 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 firmness and elasticity to the skin. Since collagen is a high-molecular-weight amino acid, it cannot be absorbed by the skin. Therefore, it can only be ingested through diet, but it is decomposed into amino acids or their trimers. The only way is to take a lot of protein, but the effect is limited.

[0003] The following formula (2)

Chem.

[0004] In Non-Patent Document 1, hydrotalcite-like compounds synthesized by the coprecipitation method are used, and glycine is used as the interlayer anion, but interlayer delamination cannot be achieved in water. The reason is that glycine accounts for about 20 mol% of the total interlayer anions, NO3 accounts for about 30 mol%, and CO3 accounts for about 50 mol%, so glycine is not the main component. It is known that carbonate-type and nitrate-type hydrotalcite-like compounds have a strong binding force with the basic layer and cannot be interlayer delaminated.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Patent Documents

[0006]

Patent Document 1

[0007] Collagen, which is an important requirement for whitening, is a high-molecular amino acid and thus cannot be ensured by the absorption method from the skin. Even if collagen is ingested, it is digested in the body and decomposed into amino acids. Therefore, it is necessary to ingest a diet rich in amino acids. Moreover, it is said that minerals and vitamin C are required for the conversion (polycondensation) from amino acids to collagen. Therefore, the conventional method of ingesting collagen through diet is inefficient. Therefore, there is an urgent need for a method of supplementing collagen that can be absorbed through the skin. [Means for Solving the Problems]

[0008] As a result of intensive research to solve the above problems, the present invention provides the following formula (1) [Chemical Formula] (In the formula, M 2+ represents at least one divalent metal, preferably Mg and / or Zn, M 3+ represents at least one trivalent metal, preferably Al, A n-It represents an n-valent anion having glycine as the main component (at least 50% or more), respectively. x and m are in the ranges of 0 < x < 0.4 and 0 < m, respectively. It has been discovered that a method of applying hydrotalcites exfoliated between layers in an aqueous medium to the skin is effective for whitening. The inventor focused on the fact that collagen is a polymer having a trimer of three types of amino acids having glycine as an essential component as a repeating unit. Based on the idea that if glycine, which is the main component of collagen, can be easily absorbed from the skin, it should be efficiently supplied to the dermis layer where collagen is formed. In order to make glycine in a state that is easily absorbed by the skin, glycine is incorporated into the interlayer of positively charged hydrotalcites that are easily permeable through the negatively charged skin, and interlayer exfoliation is performed in an aqueous medium to disperse it to a thickness of about 1 nm. Based on the above idea, a new synthesis method of hydrotalcites in which the main component of the interlayer anion is glycine, which has been difficult in the past, has been developed, enabling interlayer exfoliation in an aqueous medium. The new synthesis method is a method of calcining hydrotalcites to form oxides and then performing a hydration reaction in an aqueous glycine solution to reconstruct the structure of hydrotalcites.

Effect of the Invention

[0009] It can be made into a gel-like product that contains a large amount of glycine, has a high transparency, and has a refreshing feeling of use (because it is an aqueous medium, most cosmetics contain organic solvents and thus have a sticky feeling). Since hydrotalcites adsorb and retain water, it also has a moisturizing effect. Strengthening the moisturizing effect can be achieved by simply adding an aqueous solution of a conventionally known moisturizer, such as glycerin or amino acids. Furthermore, an aqueous solution of vitamin C and its derivatives, and a monocarboxylate of a mineral can be contained in the interlayer of hydrotalcites instead of crystal water. These agents are considered to not only contribute to the production of collagen but also to the suppression of melanin production. It can also be used for applications other than cosmetics, such as a rust inhibitor for rust-preventive paints.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0011] The present invention relates to the following formula (1)

Chemical formula

[0012] The interlayer water in formula (1) can be replaced with any polar substance. Therefore, it can be replaced with humectants such as glycerin, 3-butylene glycol, glucose, hyaluronic acid, etc., and vitamin C derivatives such as sodium ascorbyl phosphate, magnesium ascorbyl phosphate, ascorbyl glucoside, ethyl ascorbate, ascorbic acid-2-phosphate-6-palmitate, glyceryl octyl ascorbate, etc. By doing so, the former can add a moisturizing effect and the latter can add a melanin inhibitory effect. Furthermore, minerals can be supplemented with monocarboxylates of essential minerals such as Ca, Mg, Fe, Zn, Mn, Cu, etc., promoting collagen synthesis and leading to normalization of melanin turnover.

[0013] The lateral width of the primary particles (single crystals) of the hydrotalcites of formula (1) is in the range of 0.01 μm to 5 μm, and the thickness after interlayer delamination is about 1 nm. When the interlayer delaminated product of the present invention is applied to the skin, the lateral width direction of the primary particles becomes almost parallel to the skin surface, imparting slipperiness. This slipperiness tends to be better as the lateral width of the primary particles increases.

[0014] [Manufacturing method] The production of the hydrotalcites represented by formula (1) of the present invention, which exfoliate in an aqueous medium, can be carried out by calcining the hydrotalcites represented by formula (2) at 300 °C to 800 °C to form oxides, and then adding these oxides to water in which glycine is dissolved and hydrating them. The hydration reaction is preferably heated with stirring at 40 to 100 °C for 0.5 to 2 hours. The addition amount of glycine 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, a part of the water can be replaced with an alcohol such as ethanol. Furthermore, humectants such as glycerin, amino acids, ethylene glycol, propylene glycol, urea, etc., melanin inhibitors and collagen synthesis coenzymes such as vitamin C and vitamin C derivatives, and monocarboxylates of Ca, Mg, Zn, Fe, Mn, Cu, etc. can be added and contained as essential minerals. Other than these, components that can be dissolved in water can be added. However, polyvalent anions with a valence of 2 or more inhibit interlayer delamination, so it is preferable to minimize their addition as much as possible.

[0015] [Method for producing hydrotalcites before firing] The production of hydrotalcites represented by formula (2) can be carried out by coprecipitating a mixed aqueous solution of a water-soluble divalent metal salt and a trivalent metal salt, such as chlorides, nitrates, acetates of Mg, Zn, Al, etc., and an alkali such as sodium hydroxide or sodium carbonate while maintaining the pH at about 7 or higher. After the coprecipitation reaction, the interlayer anions can be converted to other anions by an ion exchange method. Since the lateral width of the primary particles obtained by the coprecipitation reaction is almost always 0.1 μm or less, when the primary particles are to be made larger than this, hydrothermal treatment is carried out. Preferably, the hydrothermal treatment is carried out at 120 to 250 °C, particularly preferably at 150 to 250 °C for 1 hour or more, preferably 5 hours or more, particularly preferably 10 hours or more. The lateral width of the primary particles can be increased in the range of 0.2 to 5 μm by the hydrothermal treatment.

[0016] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Examples

[0017] 1 L of a mixed aqueous solution of magnesium chloride and aluminum chloride (Mg = 1.0 mol / L, Al = 0.4 mol / L, about 30 °C) and an aqueous sodium hydroxide solution (4 mol / L, about 30 °C) were each supplied with a metering pump at a flow rate of 100 mL / min and about 70 mL / min, respectively, into a 3-L container with a capacity of 500 mL of water added in advance under stirring, and coprecipitated while maintaining the pH at 9.4 to 9.7. After the coprecipitate was filtered under reduced pressure, it was ion-exchanged with 1 L of a 0.4 mol / L aqueous sodium carbonate solution (about 30 °C), and then washed with 1 L of water. Water was added to the washed product and dispersed with a homogenizer, and then about half of it was put into an autoclave with a capacity of 1 L and hydrothermally treated at 140 °C for 10 hours. As a result of measuring the lateral width of the primary particles by SEM, it was about 0.4 μm on average. The hydrothermally treated slurry was filtered, dried, sieved through a 100-mesh sieve, then put into a silicon nitriding furnace and fired at 600 °C for 4 hours. The XRD of the sieved powder showed a diffraction pattern similar to that of hydrotalcite.

[0018] The XRD of the fired product is shifted slightly to the high-angle side, but shows a diffraction pattern similar to that of magnesium oxide, indicating that Al is dissolved in MgO. 17 g of reagent-grade glycine and 600 mL of deionized water were placed in a 1-L beaker and dissolved. After heating to about 70 °C, 20 g of the fired product was added with stirring, and a hydration reaction was carried out at 85 °C to 90 °C for about 40 minutes. Gelation occurred rapidly after a few minutes, and the hydration product became a transparent gel. A photograph of the XRD measurement sample holder filled with this gel and the hydrotalcite before firing is shown in Fig. 1. Through the glass attached to the back of the sample holder filled with this gel, the letters of the printed matter placed below can be clearly seen. On the other hand, the hydrotalcites before firing (interlayer anions are carbonate ions) are opaque, and the letters of the printed matter placed below cannot be seen at all. Fig. 2 shows the XRD measurement results of this gel and the gel dried at 90 °C for 5 hours. The XRD of this gel shows no diffraction peaks, indicating that the interlayers are exfoliated. The dried product of this gel shows a diffraction pattern similar to that of hydrotalcite. Combining with the fact that the transparency has decreased, it can be seen that the interlayer exfoliation is disappearing. The dried product at 90 °C for 5 hours was used to analyze CO2 by the AGK-type carbon dioxide measurement method. The same dried product was dissolved in hydrochloric acid, and Mg and Al were quantified by chelometric titration. From the above analysis results, the results of the composition investigation are as follows. [Mg 0.72 Al 0.28 (OH)2][(glycine) 0.22 (CO3) 0.03 (H2O) m (However, the amount of glycine is the theoretical value obtained by subtracting twice the number of moles of CO3 from the number of moles of Al, and m is a real number of 0 or more.)

Example

[0019] ​A 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) 1 L and an aqueous sodium hydroxide solution (4.0 mol / L, 30 °C) were respectively fed into a 3-L container with 500 mL of water previously added under stirring at a flow rate of 100 mL / min and about 80 mL / min, and the pH was maintained at about 8.9 - 9.2 for coprecipitation. After that, ion exchange, washing with water were carried out in the same manner as in Example 1, and after dispersion treatment in water, hydrothermal treatment was carried out at 120 °C for 10 hours. The hydrothermally treated product was filtered, dried, sieved (100 mesh), and then calcined at 600 °C for 3 hours. The XRD of the sieved product showed a diffraction pattern similar to that of hydrotalcite. The average of the primary particles measured by SEM was 0.2 μm.

[0020] 30 g of the calcined product was added to 700 mL of warm water (60 °C) in which 15 g of glycine was dissolved under stirring, and hydrated for 1 hour. Gelation occurred and it became transparent after several minutes. The XRD of this gel showed no diffraction peaks, indicating interlayer delamination. After drying this gel at 90 °C for 5 hours, the results of analyzing the composition by the same method as in Example 1 are shown below. [Mg 0.52 Zn 0.25 Al 0.23 (OH)2][(glycine) 0.15 (CO3) 0.04 (H2O) m (However, the amount of glycine was determined in the same manner as in Example 1. m is a real number of 0 or more)

Example

[0021] [Whitening effect test] ​The highly transparent gel obtained in Example 1 (0.5 to 0.7 g) was applied once a day to the back of one hand of three people (one woman in her 30s, one woman in her 40s, and one man in his 60s). After one month, the whiteness of the skin surface was visually compared, and the difference in smoothness was compared by touch. In all three people, the whiteness and smoothness of the skin were better when the transparent gel of the present invention was applied. For the 60-year-old man, the difference between both hands after continuing the application for 6 months is shown in Fig. 3 (photo). It is considered that the application of the product of the present invention not only reduces whiteness but also wrinkles, due to an increase in collagen in the dermis layer.

Claims

1. The following formula (1) [[(M ２＋ )( １－ｘ (M ３＋ ))( ｘ (OH) ２ )][[(A ｎ－ )( ｘ / ｎ (H ２ O))( ｍ ) (1) (However, in the formula, M ２＋ represents at least one divalent metal, M ３＋ represents at least one trivalent metal, A ｎ－ represents an n-valent anion having at least 50% or more of glycine, and x and m are respectively in the ranges of 0.1 < x < 0.4 and 0 < m), and contains hydrotalcites that exfoliate between layers in an aqueous medium as an active ingredient.

2. In formula (1), A ｎ― The whitening cosmetic according to claim 1, wherein a part of is an acidic amino acid and the pH is 6 to 8.

3. The whitening cosmetic according to claim 2, wherein the acidic amino acid is glutamic acid or aspartic acid.

4. In formula (1), M ２＋ and M ３＋ The whitening cosmetic according to any one of claims 1 to 3, wherein each is Mg and / or Zn, Al

5. The whitening cosmetic according to claims 1 to 4, wherein in formula (1), part of the interlayer water is substituted with at least one or more vitamin C derivatives.

6. In formula (1), A ｎ－ The whitening cosmetic according to any one of claims 1 to 5, wherein a part of

7. The whitening cosmetic according to claims 1 to 6, wherein in formula (1), part of the interlayer water is substituted with at least one or more of glycerin, ethylene glycol, propylene glycol, and hyaluronic acid.

8. The whitening cosmetic according to claims 1 to 7, wherein in formula (1), part of the interlayer water is substituted with a monocarboxylate of at least one essential mineral selected from Ca, Mg, Zn, Fe, Mn, and Cu.

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