JPH0948720A - Skin preparation for external use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a skin preparation for external use capable of only synergistically improving preventing and reducing effects on the skin roughening but also causing slight irritation to the skin by combining urea having softening effects on horny layers and reducing effects on the skin roughening with a specific compound. SOLUTION: This skin preparation for external use is obtained by combining urea with a low-molecular weight betaine. The low molecular weight betaine preferably includes quaternary ammonium salts of the formula (R<1> to R<3> are each a 1-6C alkyl, with the proviso that the total number of carbon atoms in the R<1> to R<3> is 8 or less). Trimethylglycine in which all the R<1> , R<2> and R<3> are methyls in the formula is most preferred. The urea is blended in an amount of preferably 0.5-7wt.%, more preferably 2-5wt.% based on the total weight of the skin preparation for external use. The low-molecular weight betaine is blended in an amount of preferably 0.01-30wt.%, more preferably 0.1-10wt.% based on the total weight of the skin preparation for external use.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an external preparation for skin,
More specifically, the present invention relates to a skin external preparation that is excellent in preventing and improving skin roughness and has low irritation to the skin.

[0002]

2. Description of the Related Art One of the major purposes of skin external preparations such as cosmetics for skin care is to maintain a beautiful skin condition. In order to maintain a beautiful skin condition, it is important to prevent and improve rough skin, prepare skin crevices and cuticles, and smooth turnover of epidermal cells. Replenishing creams and emulsions have been used and various moisturizers have been blended. Especially natural moisturizing factor (NMF: natu
Since it has been revealed that ral moisturizing factor) plays an important role in moisturizing the skin, various components (natural moisturizing factor component) contained in this factor have been applied to various cosmetics such as skin external preparations. Attempts to blend them are currently being actively made.

[0003]

The natural moisturizing factor component currently contained in the external preparation for skin is a component excellent in the moisturizing function of the skin in a physiological aspect as compared with the conventionally used moisturizing component. is there.

However, as described above, in order to maintain a beautiful skin condition, it is preferable to have not only a moisturizing function but also a positive skin roughening preventing and improving function. The natural moisturizing factor component currently used in the external preparation for skin is not necessarily satisfactory in terms of active prevention of rough skin and imparting an improving function, but among these,
Urea is a well-known component that has an effect of softening the stratum corneum and an effect of improving rough skin.

However, when this urea is compounded at a low concentration, the effect of preventing and improving skin roughness is weak, and it is usually necessary to exceed 7% by weight in order to sufficiently bring out the effect. A large amount of the compound sometimes causes skin irritation such as tingling.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an external preparation for skin which has excellent effects of preventing and improving rough skin and has less skin trouble such as skin irritation. To provide.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, the combined use of urea and a low molecular weight betaine not only synergistically improves the roughening prevention effect and the improvement effect. The inventors have found that an external preparation for skin with less occurrence of skin irritation can be obtained, and completed the present invention.

That is, according to the present invention, there is provided a skin external preparation containing urea and low molecular weight betaine.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The skin external preparation of the present invention will be described in detail below.

The urea used in the present invention is represented by the chemical formula H ₂ CONH ₂ , and may be arbitrarily used as long as it can be used in the fields of cosmetics and pharmaceuticals.

Urea is preferably incorporated in the external preparation for skin of the present invention in a proportion of 0.5 to 7% by weight, more preferably 2 to 5% by weight. If the amount is less than 0.5% by weight, the effect of the present invention may not be sufficiently exerted, and the rough skin improving effect may not be improved. On the other hand, if the amount exceeds 7% by weight, irritation to the skin may be felt. is there.

The low molecular weight betaine used in the present invention may include those which form a zwitterion with an inner salt of a quaternary ammonium base, a sulfonium base, a phosphonium base or the like having a molecular weight of about 100 to 200. Molecular weight is 100 ~
The reason for setting the molecular weight to about 200 is that betaine having a molecular weight of more than 200 has a property as a surfactant and tends to roughen the skin, while less than 100 has a strong hydrophilicity and a poor skin permeability. Because it will be. In the present invention, among these low molecular weight betaines, the following general formula (I)

[0013]

Embedded image (Wherein R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 6 carbon atoms, provided that the total number of carbon atoms of R ¹ , R ² and R ³ is 8 or less) The quaternary ammonium salt of trialkylglycine is preferably used.

In the above general formula (I), the total number of carbon atoms is 9 or more, and the molecular weights of the nitrogen atom and the alkyl groups (R ¹ , R ² and R ³ ) bonded to the nitrogen atom are relatively large. When it becomes larger, the hydrophobicity of the above portion increases, and as a result, the property of the quaternary ammonium salt as an amphoteric surfactant tends to become apparent, which is not preferable.

R ¹ , R ² and R ³ have 1 carbon atom
A wide range of straight or branched chain alkyl groups of ~ 6 can be used. That is, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec
-Butyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, tert-pentyl group, hexyl group, isohexyl group, 3-methylpentyl group,
Examples thereof include a 2,2-dimethylbutyl group and a 2,3-dimethylbutyl group. These R ¹ , R ² and R ³
May be the same or different.

As a combination of the above alkyl groups, R
^By reducing the carbon number of ¹ , R ² and R ³ as much as possible, the property of the quaternary ammonium salt represented by the general formula (I) as an amphoteric surfactant can be reduced as much as possible. It is preferable in that there is a tendency. That is, in the general formula (I), trimethylglycine in which R ¹ , R ² and R ³ are all methyl groups is most preferably used.

The low molecular weight betaine is preferably blended in the skin external preparation of the present invention in a proportion of 0.01 to 30% by weight, more preferably 0.1 to 10% by weight, particularly preferably 1 to 5% by weight. %. If it is less than 0.01% by weight, the stickiness of other moisturizers (such as mucopolysaccharides) that may be contained in the external preparation for skin cannot be suppressed sufficiently, while if it exceeds 30% by weight, the effect of the present invention is obtained. Can not be expected, and the powdery feeling is felt, and the familiarity with the skin is deteriorated.

In the external preparation for skin of the present invention, the combined use of urea and low-molecular-weight betaine has a significantly excellent effect of preventing rough skin and improving rough skin compared to the case where urea and low-molecular betaine are blended individually. As well as getting
It is possible to obtain an excellent feeling of use that is not irritating to the skin due to the addition of urea and does not have the powdery appearance associated with the addition of low molecular weight betaine.

The external preparation for skin of the present invention may include cosmetics, pharmaceuticals, quasi drugs, etc., all of which are applied to the outer skin.

Therefore, the dosage form is also an aqueous system, a solubilizing system (for example, lotion), an emulsifying system (for example, emulsion, cream, etc.), a powder system, an oil liquid system, a gel system, an ointment system, water-oil 2
It can take a wide variety of forms such as a layer system and a water-oil-powder trilayer system.

In addition to the above-mentioned essential components, the external preparation for skin of the present invention may appropriately contain other components usually used for external preparations for skin such as cosmetics and pharmaceuticals. For example, powder components such as titanium dioxide, mica, and talc; evening primrose oil, avocado oil, mink oil, jojoba oil, macadamia nut oil, corn oil, rapeseed oil, castor oil, sunflower oil, cacao oil, coconut oil, rice bran oil, olive oil , Lanolin, squalene and other natural animal and vegetable oils and fats; liquid paraffin, squalane, petrolatum and other hydrocarbons; paraffin wax,
Wax such as whale wax, beeswax, candelilla wax and carnauba wax; higher alcohols such as cetanol and stearyl alcohol; myristic acid, palmitic acid, stearic acid, behenic acid, isostearic acid, oleic acid, linolenic acid, linoleic acid, oxy Higher fatty acids such as stearic acid; isopropyl myristic acid, isopropyl palmitic acid, isopropyl stearic acid, 2
Esters such as glycerol ethylhexanoate; polar oils such as diethylene glycol monopropyl ether, polyoxyethylene polyoxypropylene pentaerythritol ether, polyoxypropylene butyl ether, ethyl linoleate, and other silicone oils; para-aminobenzoic acid, homomethyl-7N-acetyl Allantoylanilate, butylmethoxybenzoylmethane, di-paramethoxycinnamic acid-glyceryl mono-2-ethylhexanoate, amyl salicylate, octyl cinnamate,
Ultraviolet absorbers such as 2,4-dihydroxybenzophenone; Moisturizers such as polyethylene glycol, sorbitol, xylitol, maltitol; Thickeners such as methyl cellulose, gum arabic, polyvinyl alcohol, montmorillonite, laponite; Ethanol, 1,3-butylene Organic solvents such as glycols; Antioxidants such as butylhydroxytoluene, tocopherol, phytic acid; Benzoic acid, salicylic acid, sorbic acid, paraoxybenzoic acid alkyl esters (ethylparaben, butylparaben, etc.), antibacterial agents such as hexachlorophene Acyl sarcosine acids (eg sodium lauroyl methyl sarcosine), glutathione, citric acid, malic acid, tartaric acid,
Organic acids such as lactic acid; vitamin A and its derivatives; vitamins B ₆ hydrochloride, vitamin B ₆ tripalmitate, vitamin B ₆ dioctanoate, vitamin B ₂ and its derivatives, vitamins B ₁₂ , vitamin B ₁₅ and its derivatives, etc. Bs; ascorbic acid, ascorbic acid sulfate (salt), ascorbic acid phosphate (salt),
Vitamin Cs such as ascorbic acid dipalmitate; α-
Vitamin Es such as tocopherol, β-tocopherol, γ-tocopherol, vitamin E-acetate, vitamin E-nicotinate; vitamins such as vitamin Ds, vitamin H, pantothenic acid, pantothetin; nicotinamide, benzyl nicotinate , Γ-oryzanol, allantoin, glycyrrhizic acid (salt), glycyrrhetinic acid and its derivatives, hinokitiol, mucidin, bisabolol, eucalyptol, thymol inositol, saponins (carrot saponin, hemimasaponin, muclodisaponin, etc.), pantoterethyl ether , Ethinyl estradiol, tranexamic acid, cephalandin,
Various agents such as placenta extract; Rumex, Clara, Kohone, orange, sage, saw grass, mallow,
Organic solvents such as senkyu, senburi, thyme, touki, spruce, birch, horsetail, loofah, horse chestnut, yukinoshita, arnica, lily, mugwort, peony, aloe, gardenia, sawara, alcohol, polyhydric alcohol, water,
Natural extracts extracted with aqueous alcohol and the like; pigments; sorbitan monolaurate, sorebitan sesquioleate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyethylene glycol monooleate, polyoxyethylene alkyl ether, polyglycol diester, lauroyl diethanol amide , Nonionic surfactants such as fatty acid isopropanol amide, maltitol hydroxyaliphatic ether, alkylated polysaccharides, alkyl glucosides and sugar esters; cationic surfactants such as stearyl trimethyl ammonium chloride, benzalkonium chloride and lauryl amine oxide; palmitin Sodium acid salt, sodium laurate, potassium lauryl sulfate, triethanolamine alkyl sulfate, funnel oil Linear dodecylbenzene sulfate, polyoxyethylene hardened castor oil maleic acid, anionic surfactants such as acyl methyl taurine; perfumes; can be blended purified water.

[0022]

EXAMPLES Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. In addition, all compounding amounts represent% by weight.

Prior to the examples, the test method used in the present invention,
The evaluation method will be described.

[Rough skin improvement effect] An active agent (sodium lauryl sulfate) was applied to some places on the forearms of about 10 male panels.
A 10% aqueous solution was applied for 3 days to intentionally cause rough skin. Then, the example products and the comparative example products having the formulations shown in the following Tables 1 to 3 were applied to the rough skin portion twice a day, and the skin surface condition was measured 5 days after the start of application by the replica method and the skin conductance. After the skin was rough, the skin improvement effect was evaluated by the following criteria as compared with the area where nothing was applied. (Judgment criteria) Significant effect: The symptoms of rough skin disappeared Effective: The symptoms of rough skin weakened Slightly effective: The symptoms of rough skin became slightly weaker Invalid: The symptoms of rough skin did not change. Symptoms of (1) stratum corneum exfoliation, erythema occurs, (2) sulcus and crust are not clear,
This indicates that the skin texture is not uniform. (Evaluation) ⊚: 80% or more of subjects who evaluated excellent, effective, and slightly effective ○: 50 to less than 80% of subjects who evaluated excellent, effective, and slightly effective Δ: excellent, effective, 30% to less than 50% of the subjects evaluated to be slightly effective. X: Less than 30% of the subjects evaluated to be excellent, effective, and slightly effective.

[Skin Irritation] In the above-mentioned test for improving the rough skin, it was evaluated whether or not the skin was tingling. The average evaluation is shown. (Score) 0: No tingling of the skin was felt at all 1: Slight irritation of slight itchiness was felt 2: Skin irritation (erythema, tingling) was felt (Evaluation) ○: Average score less than 0.2 △ : Average score of 0.2 or more and less than 0.5 x: Average score of 0.5 or more Example 1, Comparative Examples 1 to 5 (lotion) Lotions having the formulations shown in Table 1 below were prepared. In particular,
Polyoxyethylene oleyl ether and methylparaben were dissolved in a part of ethanol (ethanol phase).
Separately from this, propylene glycol, trimethylglycine and urea were dissolved in purified water and the rest of ethanol to prepare (aqueous phase). Next, an ethanol phase was added to the aqueous phase and solubilized to obtain a lotion. Using this, the rough skin improving effect and skin irritation were evaluated by the above test method.

[0026]

[Table 1] As is clear from Table 1, the use of trimethylglycine or urea alone has a low effect of improving rough skin, but a system in which these are used in an appropriate combination has no irritation to the skin, and the effect of improving rough skin increases synergistically. I understood.

Examples 2 to 7 and Comparative Examples 6 to 9 (Emulsion) Emulsions having the formulations shown in Tables 2 to 3 below were prepared. Specifically, the oil components (5) to (9), (12) and (13) are uniformly dissolved and maintained at 70 ° C. The water phase of (2), (3), (10) and (11) dissolved in a part of (1) is uniformly dissolved in a separate pot. Add the oil phase parts to the water phase,
(4) dissolved in a part of (1) was added to obtain an emulsified composition. Using this, skin roughening improvement effect by the above test method,
The irritation to the skin was evaluated.

[0028]

[Table 2]

[0029]

[Table 3] As is clear from Tables 2 and 3, the use of trimethylglycine or urea alone has a low skin roughening improving effect, but in a system in which these are appropriately used in combination, the skin roughening improving effect is synergistically increased without irritation to the skin. I found out that

[0030]

As described in detail above, according to the present invention, by containing urea and a low molecular weight betaine, a synergistic effect of both is shown, and an excellent effect of improving rough skin is obtained, and the skin is less irritating to the skin. The effect that an external preparation is provided is exhibited.

Claims (7)

[Claims] 1. A method comprising urea and low-molecular-weight betaine,
External preparation for skin. 2. A low molecular weight betaine has the following general formula (I): (Wherein R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 6 carbon atoms, provided that the total number of carbon atoms of R ¹ , R ² and R ³ is 8 or less) The external skin preparation according to claim 1, which is a quaternary ammonium salt. 3. In the general formula (I), R ¹ , R ² and R ³
The external preparation for skin according to claim 2, wherein each is a methyl group. 4. The external preparation for skin according to claim 1, wherein 0.5 to 7% by weight of urea is mixed in the total amount of the external preparation for skin. 5. Urea is 2 to 5% by weight in the total amount of the external preparation for skin.
The external preparation for skin according to any one of claims 1 to 3, which is blended. 6. The external preparation for skin according to any one of claims 1 to 5, which comprises 0.01 to 30% by weight of low-molecular-weight betaine in the total amount of the external preparation for skin. 7. The external preparation for skin according to claim 1, wherein 0.1-10% by weight of low-molecular-weight betaine is mixed in the total amount of the external preparation for skin.