WO2013018481A1

WO2013018481A1 - Topical cosmetic skin preparation and method of production, composition comprising an ascorbyl - 2 - phosphate - 6 - higher fatty acid salt and a nonionic surfactant

Info

Publication number: WO2013018481A1
Application number: PCT/JP2012/066826
Authority: WO
Inventors: Naoko Ito
Original assignee: Showa Denko K.K.
Priority date: 2011-08-01
Filing date: 2012-06-26
Publication date: 2013-02-07
Also published as: JP5865623B2; JP2013032303A

Abstract

Topical skin preparation containing an ascorbyl 2-phosphate-6-higher fatty acid salt. Composition displays good stability. A method of production of said composition is also claimed. The composition of the invention further comprises a nonionic surfactant (1) represented by the following formula: R¹-0-(R²0)_m-(CH₂CH₂0)_n-H...(1), 1 2 wherein, R represents a linear or branched alkyl group, R represents -CH₂CH(CH₃)- or -CH(CH₃)CH ₂ -, and m and n are each positive integers, wherein the average value of m is from 2 to 25, and the average value of n is 3 to 34.

Description

DESCRIPTION

TOPICAL COSMETIC SKIN PREPARATION AND METHOD OF PRODUCTION, COMPOSITION COMPRISING AN ASCORBYL - 2 - PHOSPHATE - 6 - HIGHER FATTY ACID SALT AND A NONIONIC SURFACTANT

TECHNICAL FIELD

[0001]

The present invention relates to an external skin preparation and a method for producing the same.

Priority is claimed on Japanese Patent Application No. 2011-168580, filed August 1, 2011, the contents of which are incorporated herein by reference.

BACKGROUND ART

[0002]

Ascorbic acid (vitamin C) and various derivatives thereof are known to be

compounds that demonstrate actions and effects such as whitening action, antioxidative action and collagen synthesis-promoting action, and are incorporated in pharmaceuticals, cosmetics, animal feeds and the like.

Among ascorbic acid derivatives, ascorbyl 2-phosphate derivatives, in which a hydroxyl group at position 2 of ascorbic acid is converted to a phosphate ester, are

commonly used since they are resistant to oxidation in air. Known examples of ascorbyl 2-phosphate derivatives include ascorbyl 2-phosphate and ascorbyl 2-phosphate-6-higher fatty acids in which a hydroxyl group at position 6 thereof is esterified by a higher fatty acid such as palmitic acid and these are normally used in the form of salts. Typical

examples of such salts include sodium salts or magnesium salts of ascorbyl 2-phosphate and sodium salts of ascorbyl 2-phosphate-6-higher fatty acids.

[0003] Among the derivatives described above, since ascorbyl 2-phosphate-6-higher fatty acid salts are amphiphilic, they demonstrate high affinity for the body and rapidly migrate to body tissue such as the skin, and are expected to be applied to cosmetics and other external skin preparations.

However, when formulating an ascorbyl 2-phosphate-6- higher fatty acid salt for use as an external skin preparation, decomposition occurs within the preparation resulting in problems such as a change in appearance. The occurrence of precipitation not only changes appearance, but also causes an unpleasant sensation when the external skin preparation is applied to skin.

Decomposition of ascorbyl 2-phosphate-6-higher fatty acid salts is mainly caused by hydrolysis of the higher fatty acid esterbonded to the hydroxyl group at position 6 of ascorbic acid. As a result of this decomposition, water-insoluble higher fatty acid salts such as sodium palmitate form and appear as a precipitate in the preparation. Although these precipitates are unable to be confirmed visually in turbid drug forms such as creams, in the case of clear lotions or beauty essences and the like, problems caused by changes in appearance occur in the form of turbidity and precipitation.

In addition, since the solubility of ascorbyl 2-phosphate 6-higher fatty acid salts decreases in the case of being stored at low temperatures, there is also the problem of the ascorbyl 2-phosphate-6-higher fatty acid salt per se undergoing precipitation within the preparation in which it is incorporated. There is particular susceptibility to the occurrence of this problem in the case of incorporating sodium ascorbyl

2-phosphate-6-palmitate.

[0004]

Various methods have been previously proposed for stabilizing external skin preparations by incorporating other components with ascorbyl 2-phosphate-6-higher fatty acid salts.

For example, Patent Document 1 discloses a method that comprises the

incorporation of a water-soluble synthetic polymer compound such as carboxyvinyl polymer and water as a method for stabilizing an external skin preparation containing an ascorbyl 2-phosphate-6-higher fatty acid salt. According to this method, decomposition and a resulting reduction in the ascorbyl 2-phosphate-6-higher fatty acid salt in the external skin preparation are inhibited, thereby making it possible to inhibit the occurrence of coloration and precipitation of the external skin preparation over time.

Patent Document 2 discloses a method comprising the incorporation of a polyvalent alcohol as a method for stabilizing an external skin preparation containing an ascorbyl 2-phosphate-6-higher fatty acid salt. According to this method, the occurrence of turbidity and precipitation of the external skin preparation over time can be inhibited.

Patent Document 3 discloses a method for making an average emulsion particle diameter be in a range from 1 to 200 nm by using a polyglycerin fatty acid ester containing polyglycerin having an average degree of polymerization of 8 to 12 and an unsaturated fatty acid residue having 14 to 22 carbon atoms, and a polyglycerin mono fatty acid ester containing polyglycerin having an average degree of polymerization of 2 to 6 and an unsaturated fatty acid residue having 14 to 22 carbon atom, as an emulsifier, as a method for stabilizing an external skin preparation containing an ascorbyl

2-phosphate-6-higher fatty acid salt. According to this method, decomposition of the ascorbyl 2-phosphate-6-higher fatty acid salt in the external skin preparation is inhibited, storage stability is also improved, and an attractive transparent to semi-transparent appearance can be maintained.

Furthermore, ascorbic acid and derivatives thereof are also used to stabilize other active ingredients in addition to their use as active ingredients of external skin preparations and the like in consideration of their antioxidative action. For example, Patent Document 4 proposes the incorporation of at least one type of a component A: storage stabilizer, organic acid having a chelating effect or salt thereof, a component B: nonionic surfactant, a component C: ascorbic acid, derivative thereof or salt thereof, and a component D: ultraviolet protector, in order to enhance the stability of a composition containing fullerene, a derivative thereof, an inclusion compound or a salt thereof that has poor stability on its own.

[0005]

However, in the case of a method that incorporates a water-soluble synthetic polymer compound as disclosed in Patent Document 1, although the effect of inhibiting decomposition of an ascorbyl 2-phosphate-6-higher fatty acid salt is obtained to a certain degree, the preparation is unstable in that, for example, viscosity decreases and precipitation and coloration occur easily due to a change in pH or the addition of a dissociating compound such as sodium chloride or sodium citrate. In particular, although incorporation of a carboxyvinyl polymer is effective for stabilizing emulsification since it increases the viscosity of the system, since a neutralization procedure is carried out by adding a strongly alkaline agent such as potassium hydroxide or sodium hydroxide, decomposition of an ascorbyl 2-phosphate-6-higher fatty acid salt proceeds easily resulting in prominent precipitation and coloration over time.

In the case of a method that incorporates a polyvalent alcohol as disclosed in Patent Document 2, a preparation tends to become unstable due to a decrease in viscosity resulting from the use of a large amount of polyvalent alcohol when the preparation contains an emulsifier.

In the case of a method that incorporates a polyglycerin mono fatty acid ester as disclosed in Patent Document 3, emulsification becomes unstable due to addition of a dissociating compound such as sodium chloride or sodium citrate, and depending on the type of compounds incorporated, results in problems that limit the type of preparation to which the method can be applied, such as being unable to be applied to transparent lotion systems that do not contain oil due to the occurrence of creaming.

The method disclosed in Patent Document 4 is a method for improving the stability of fullerenes, is not a method for improving the stability of an ascorbyl

2-phosphate-6-higher fatty acid salt per se, and depending on the incorporated components, may impair stability of an ascorbyl 2-phosphate- 6-higher fatty acid salt.

On the basis of this background, there is strong desire to create an external skin preparation that contains an ascorbyl-2- phosphate-6-higher fatty acid salt, has superior preparation stability, inhibits turbidity and precipitation over time, and has a superior feel. [Prior Art Documents]

[Patent Documents]

[0006]

[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2005-187466

[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2005-336156

[Patent Document 3] Japanese Unexamined Patent Application, First Publication No. 2008-13464

[Patent Document 4] Japanese Unexamined Patent Application, First Publication No. 2004-269523

DISCLOSURE OF THE INVENTION

[Problems to be Solved by the Invention] [0007]

With the foregoing in view, an object of the present invention is to provide an external skin preparation that contains an ascorbyl 2-phosphate-6-higher fatty acid salt and has superior preparation stability, and a production method thereof.

[Means for Solving the Problems]

[0008]

As a result of conducting extensive studies to solve the aforementioned problems, the inventor of the present invention found that the aforementioned object is achieved by combining a specific nonionic surfactant with an ascorbyl 2-phosphate-6- higher fatty acid salt, thereby leading to completion of the present invention.

The present invention has the aspects described below.

[ 1 ] An external skin preparation containing:

an ascorbyl 2-phosphate-6-higher fatty acid salt and

a nonionic surfactant (1) represented by the following formula (1):

R^O-C^O CHzCHzO H ...(1)

[wherein, R 1 represents a linear or branched alkyl group, R 2 represents -CH₂CH(CH₃)- or -CH(CH₃)CH₂-, and m and n are each positive integers],

wherein the average value of m in formula (1) is 2 to 25, and the average value of n is 3 to 34.

[2] The external skin preparation described in [1], wherein the average value of m in formula (1) is 6 to 12 and the average value of n is 12 to 30.

[3] The external skin preparation described in [1] or [2], wherein the external skin perpartion contains only the ascorbyl 2-phosphate-6-higher fatty acid salt as an ascorbyl 2-phosphate derivative.

[4] The external skin preparation described in any one of [1] to [3], wherein the ascorbyl 2-phosphate-6-higher fatty acid salt is ascorbyl 2-phosphate-6-palmitate.

[5] The external skin preparation described in any one of [1] to [4], wherein the ascorbyl 2-phosphate-6-higher fatty acid salt is an alkaline metal salt.

[6] The external skin preparation described in any one of [1] to [5], wherein the content of the nonionic surfactant (1) is 0.1% by mass to 10% by mass.

[7] The external skin preparation described in any one of [1] to [6], wherein the content of the ascorbyl 2-phosphate-6-higher fatty acid salt is 0.01% by mass to 10% by mass.

[8] The external skin preparation described in any one of [1] to [7], wherein the pH thereof is 6.5 to 7.5.

[9] The external skin preparation described in any one of [1] to [8], further containing a nonionic surfactant (2) represented by the following formula (2):

HO-(CH₂CH₂0)a-(R³0)_b-(CH₂CH₂0)c-H ... (2)

[wherein, R³ represents -CH₂CH(CH3)- or -CH(CH3)CH₂-, and a, b and c are each positive integers].

[10] The external skin preparation described in [9], wherein the average value of a + c in the formula (2) is 4 to 400, and the average value of b is 5 to 70.

[11] The external skin preparation described in [9] or [10], wherein the content of the nonionic surfactant (2) is 0.1% by mass to 10% by mass.

[12] The external skin preparation described in any one of [1] to [11], wherein the external skin preparation is a cosmetic.

[13] A production method of an external skin preparation including:

a step of incorporating an ascorbyl 2-phosphate-6-higher fatty acid salt and a nonionic surfactant (1) represented by the following formula (1):

[wherein, 1 inear or branched alkyl group, 2

R represents a l R represents -CH₂CH(CH₃)- or -CH(CH3)CH₂-, and m and n are each positive integers], wherein the average value of m in formula (1) is 2 to 25, and the average value of n is 3 to 34.

[14] The production method of an external skin preparation described in [13], wherein the average value of m in the formula (1) is 6 to 12 and the average value of n is 12 to 30.

[15] The production method of an external skin preparation described in [13] or [14], wherein only the ascorbyl 2-phosphate-6-higher fatty acid salt is incorporated as an ascorbyl 2-phosphate derivative.

[16] The production method of an external skin preparation described in any one of [13] to [15], wherein the nonionic surfactant (1) is incorporated such that the content thereof in the total amount of the external skin preparation is 0.1% by mass to 10% by mass.

[17] The production method of an external skin preparation described in any one of [13] to [16], wherein the ascorbyl 2-phosphate-6-higher fatty acid salt is incorporated such that the content thereof in the total amount of the external skin preparation is 0.01% by mass to 10% by mass.

[18] The production method of an external skin preparation described in any one of [13] to [17], the production method further includes a step of incorporating a nonionic surfactant (2) represented by the following formula (2):

HO-(CH₂CH₂0)_a-(R³0)_b-(CH₂CH₂0)_c-H ...(2)

[wherein, R³ represents -CH₂CH(CH₃)- or -CH(CH₃)C¾-, and a, b and c are each positive integers].

[19] The production method of an external skin preparation described in [18], wherein the nonionic surfactant (2) is incorporated such that the content thereof in the total amount of the external skin preparation is 0.1% by mass to 10% by mass.

[Effects of the Invention]

[0009] According to the present invention, an external skin preparation, which contains an ascorbyl 2-phosphate-6-higher fatty acid salt and has superior preparation stability, and a production method thereof, can be provided.

DETAILED DESCRIPTION OF THE INVENTION

[0010]

The ascorbyl 2-phosphate-6-higher fatty acid salt is a compound that has formed a salt with an anion and a counter ion, the anion being formed by phosphoric acid being ester-bonded to a hydroxyl group bonded to a carbon atom at position 2 of ascorbic acid, a higher fatty acid being ester-bonded to a hydroxyl group bonded to a carbon atom at position 6, and dissociation of at least one of the hydrogen atoms of the two hydroxyl groups bound to the phosphorous atom in the phosphate group and the hydroxyl group bonded to the carbon atom at position 3 of ascorbic acid, an example of which is a salt of a counter ion and an anion represented by the structural formula indicated below.

Furthermore, a higher fatty acid refers to a fatty acid having 11 or more carbon atoms.

The number of carbon atoms of the aforementioned higher fatty acid is preferably 12 to 28 in consideration of handling ease as an ascorbyl 2-phosphate-6-higher fatty acid salt.

The aforementioned counter ion is preferably an alkaline metal ion. Namely, an alkaline metal salt is preferable for the ascorbyl 2-phosphate-6-higher fatty acid salt.

Specific examples of alkaline metals include sodium and potassium.

[0011]

[Chemical Formula 1]

[0012]

As will be subsequently described, although an ascorbyl 2-phosphate derivative other than an ascorbyl 2-phosphate-6- higher fatty acid salt may be incorporated in the external skin preparation of the present invention, when only an ascorbyl

2-phosphate-6-higher fatty acid salt is incorporated for the ascorbyl 2-phosphate derivative, decomposition of the ascorbyl 2-phosphate-6-higher fatty acid salt is further inhibited, stability of the preparation improves, and there is less susceptibility to increases in coloration, precipitation and the like.

In terms of facilitating the obtaining of such effects, ascorbyl

2-phosphate-6-palmitate is preferable, an alkaline metal salt of an ascorbyl

2-phosphate-6-higher fatty acid salt is more preferable, a sodium ascorbyl

2-phosphate-6-higher fatty acid salt is even more preferable, and sodium ascorbyl 2-phosphate-6-palmitate is particularly preferable for the ascorbyl 2-phosphate-6-higher fatty acid salt.

[0013]

One type of ascorbyl 2-phosphate-6-higher fatty acid salt may be used alone or two or more types may be used in combination.

The incorporated amount of the ascorbyl 2-phosphate-6-higher fatty acid salt in the total amount of the external skin preparation is preferably 0.01% by mass to 10% by mass and more preferably 0.5% by mass to 5% by mass. If the incorporated amount is 0.01% by mass or more, the ascorbyl 2-phosphate-6-higher fatty acid salt rapidly migrates to the skin when the external skin preparation of the present invention is applied to the skin, thereby enabling the actions and effects required of the external skin preparation to be adequately demonstrated. Greater effects are not necessarily obtained if incorporated in excess of 10% by mass, thereby making this uneconomical.

[0014]

In addition to the ascorbyl 2-phosphate-6-higher fatty acid salt, the external skin preparation of the present invention contains a nonionic surfactant (1) represented by the following formula ( 1 ) :

[wherein, R represents a linear or branched alkyl group, R represents -CH₂CH(CH₃)- or -CH(CH3)CH₂-, and m and n are each positive integers], wherein the average value of m in formula (1) is 2 to 25, and the average value of n is 3 to 34.

The nonionic surfactant (1) is a POE-POP alkyl ether in which a linear or branched alkyl alcohol and a polyoxyethylene (POE) chain (CH₂CH₂0)_n) are ether-bonded, and a polyoxypropylene (POP) chain ((R 0)_m) is ether-bonded to the linear or branched alkyl chain and the POE chain.

[0015]

In the aforementioned formula (1), R¹ represents a linear or branched alkyl group. The alkyl group of R¹ may be linear or branched, the degree of branching is preferably low, and an alkyl group that is branched at one location or a linear alkyl group is preferable. Although there are no particular limitations on the number of carbon atoms of R¹, it is preferably 8 to 30, more preferably 10 to 26 and even more preferably 16 to 24. Although there are no particular limitations on the linear or branched alkyl group of R¹, examples include a decyl group, lauryl group, cetyl group, stearyl group and decyltetradecyl group.

In the aforementioned formula (1), m indicates the number (degree of

polymerization) of an oxypropylene group (CH₂CH(CH₃)0 or CH(C¾)CH₂0) that composes the POP chain. In addition, n indicates the number (degree of

polymerization)of an oxyethylene group (CH₂CH₂0) that composes the POE chain.

In the nonionic surfactant (1), the average value of m, namely the number (average degree of polymerization) of an oxypropylene group per molecule of the nonionic surfactant (1) is 2 to 25, preferably 3 to 25 and more preferably 5 to 34. In addition, the average value of n, namely the number (average degree of polymerization) of an oxyethylene group per molecule of the nonionic surfactant (1) is 3 to 34, preferably 6 to 12 and even more preferably 3 to 34. If the values of m and n are each within the aforementioned ranges, preparation stability of the external skin preparation is adequately obtained.

Although there are no particular limitations on the average value of m + n, namely the total number of the oxypropylene groups and the oxyethylene groups per molecule of the nonionic surfactant (1), provided the values of m and n are each within the

aforementioned ranges, it is preferably 5 to 59 and more preferably 25 to 38.

Although there are no particular limitations on the ratio of m/n provided the values of m and n are each within the aforementioned ranges, it is preferably 0.05 to 20 and more preferably 0.2 to 1.

[0016]

Specific examples of the nonionic surfactant (1) include, but are not limited to, POE(4)POP(2) decyl ether, POE(7)POP(2) decyl ether, POE(8)POP(2) decyl ether, POE(10)POP(2) decyl ether, POE(15)POP(2) decyl ether, POE(20)POP(2) decyl ether, POE(30)POP(2) decyl ether, POE(40)POP(2) decyl ether, POE(8)POP(2) lauryl ether, POE(15)POP(4) lauryl ether, POE(10)POP(4) cetyl ether, POE(20)POP(4) cetyl ether, POE(20)POP(8) cetyl ether, POE(20)POP(6) decyltetradecyl ether and POE(30)POP(6) decyltetradecyl ether. Among these, POE(20)POP(8) cetyl ether, POE(12)POP(6) decyltetradecyl ether, POE(20)POP(6) decyltetradecyl ether, and POE(30)POP(6) decyltetradecyl ether are preferable. Furthermore, values shown in parentheses following POE indicate the average degree of polymerization of the POE chain (namely, the average number of n in the aforementioned formula (1)). Values shown in parentheses following POP indicate the average degree of polymerization of the POP chain (namely, the average value of m in the aforementioned formula (1)).

The nonionic surfactant (1) may be produced according to a known production method or a commercially available product may be used. Examples of commercially available products include members of the Emalex series (trade name, Nihon Emulsion Co., Ltd.), members of the Noygen series (trade name, Dai-Ichi Kogyo Seiyaku Co., Ltd.), and members of the NIKKOL PBC series and NIKKOL PEN series (trade names, Nikko Chemicals Co., Ltd.).

[0017]

The nonionic surfactant (1) may be used alone or two or more types may be used in combination.

The content of the nonionic surfactant (1) in the total amount of the external skin preparation is preferably 0.1% by mass to 10% by mass and preferably 0.5% by mass to 2% by mass. If the content of the nonionic surfactant (1) is 0.1% by mass or more, the resulting preparation has superior stability and is not susceptible to the occurrence of precipitation and turbidity during storage. Greater effects are not necessarily obtained if incorporated in excess of 10% by mass, thereby making this uneconomical.

[0018]

The external skin preparation of the present invention preferably further contains a nonionic surfactant (2) represented by the following formula (2):

HO-(CH₂CH₂0)_a-(R³0)_b-(CH₂CH₂0)c-H ...(2)

[wherein, R represents -CH₂CH(CH₃)- or -CH(CH₃)CH₂-, and a, b and c are each positive integers].

The nonionic surfactant (2) is a POE-POP glycol having the structure of a

POE-POP-POE block copolymer in which a POP chain is ether-bonded between POE chains (to be referred to as a POE-POP-POE type).

Further incorporating this nonionic surfactant (2) further improves preparation stability of the external skin preparation over a wide temperature range from low temperatures to high temperatures.

[0019]

In the aforementioned formula (2), a indicates the number (degree of

polymerization) of an oxyethylene group that composes the POE chain (CH₂CH₂0). b indicates the number (degree of polymerization) of an oxypropylene group that composes the POP chain (R³0). c indicates the number (degree of polymerization) of an oxyethylene group that composes the other POE chain (CH₂CH₂0) (degree of

polymerization).

In the nonionic surfactant (2), the average value of a + c, namely the number (average degree of polymerization) of the oxyethylene group per molecule of the nonionic surfactant (2) is preferably 4 to 400 and more preferably 20 to 160. In addition, the average value of b, namely the number (average degree of polymerization) of the oxypropylene group per molecule of the nonionic surfactant (2) is preferably 5 to 70 and more preferably 20 to 50. If the values of (a + c) and b are each within the

aforementioned ranges, the effect of improving preparation stability of the external skin preparation is superior.

The average value of a + b + c, namely the total number of the oxypropylene group and the oxyethylene group per molecule of the nonionic surfactant (2), is preferably 7 to 470 and more preferably 20 to 100.

The ratio of (a + c)/b is preferably 0.05 to 80 and more preferably 0.3 to 3.

[0020]

Specific examples of the nonionic surfactant (2) include, but are not limited to, POE(5)POP(5) glycol, POE(5)POP(30) glycol, POE(10)POP(8) glycol, POE(16)POP(17) glycol, POE(20)POP(20) glycol, POE(25)POP(30) glycol, POE(35)POP(40) glycol, POE(100)POP(40) glycol, POE(300)POP(55) glycol and POE(400)POP(70) glycol.

Among these, POE(25)POP(30) glycol and POE(35)POP(40) glycol are more preferably from the viewpoint of preparation stability of the external skin preparation.

Furthermore, all of these compounds are POE-POP-POE type POE-POP glycols. Values shown in parentheses follo wing POE indicate the average degree of polymerization of the POE chain (namely, the average number of a + c in the aforementioned formula (2)). Values shown in parentheses following POP indicate the average degree of polymerization of the POP chain (namely, the average value of b in the aforementioned formula (2)).

The nonionic surfactant (2) may be produced according to a known production method or a commercially available product may be used. Examples of commercially available products include members of the Adeka Pluronic L series, Adeka Pluronic P series and Adeka Pluronic F series (trade names, Adeka Corp.), as well as members of the Newpol PE series (trade name, Sanyo Chemical Industries, Ltd.). [0021]

The nonionic surfactant (2) may be used alone or two or more types may be used in combination.

In the case of incorporating the nonionic surfactant (2), the content of the nonionic surfactant (2) in the total amount of the external skin preparation is preferably 0.1% by mass to 10% by mass and preferably 0.5% by mass to 2% by mass. If the content of the nonionic surfactant (2) is 0.1% by mass or more, the effect of incorporating the nonionic surfactant (2) is adequately obtained. Greater effects are not necessarily obtained if incorporated in excess of 10% by mass, thereby making this uneconomical.

[0022]

The external skin preparation of the present invention may also incorporate at least one type selected from the group consisting of ascorbic acid and salts thereof as well as ascorbic acid derivatives other than ascorbyl 2-phosphate-6- higher fatty acid salts.

Examples of salts of ascorbic acid include sodium salts and potassium salts.

Examples of ascorbic acid derivatives other than ascorbyl 2-phosphate-6-higher fatty acid salts include ascorbyl 2-phosphoric acid and salts thereof, ascorbyl 3-phosphate- 6-higher fatty acids and salts thereof, ascorbyl 6-higher fatty acids and salts thereof, ascorbyl 2,6-di-higher fatty acids and salts thereof, ascorbyl 2,3,5,6-tetra-higher fatty acids and salts thereof, ascorbyl 2-sulfuric acid and salts thereof and ascorbyl 2-glucosides. Examples of salts include sodium salts and potassium salts. Examples of higher fatty acids include fatty acids having 8 to 22 carbon atoms.

However, the external skin preparation of the present invention preferably only incorporates the aforementioned ascorbyl 2-phosphate-6-higher fatty acid salt for the ascorbyl 2-phosphate derivative. Namely, the external skin preparation of the present invention preferably does not incorporate an ascorbyl 2-phosphate derivative other than the ascorbyl 2-phosphate-6-higher fatty acid salt. According to studies conducted by the inventor of the present invention, incorporating only the ascorbyl 2-phosphate-6-higher fatty acid salt more effectively inhibits decomposition of the ascorbyl

2-phosphate-6-higher fatty acid salt and more easily improves preparation stability than incorporating the ascorbyl 2-phosphate-6-higher fatty acid salt with another ascorbyl 2-phosphate derivative. Namely, more superior preparation stability is obtained by not incorporating an ascorbyl 2-phosphate derivative other than the ascorbyl

2-phosphate-6-higher fatty acid salt.

An ascorbyl 2-phosphate derivative refers to an ascorbic acid derivative in which phosphoric acid is ester-bonded to at least the hydroxyl group bonded to the carbon atom at position 2 of ascorbic acid. Among the aforementioned ascorbic acid derivatives, examples of ascorbyl 2-phosphate derivatives other than the ascorbyl

2-phosphate-6-higher fatty acid salt include ascorbyl 2-phosphoric acid and salts thereof.

Furthermore, within the external skin preparation, the ascorbyl

2-phosphate-6-higher fatty acid salt may decompose to form a higher fatty acid and ascorbyl 2-phosphoric acid. Consequently, a trace amount of ascorbyl 2-phosphoric acid or salt thereof may be contained in the external skin preparation of the present invention even if it is not incorporated during production.

In addition, in the external skin preparation, the phosphate group at position 2 of the ascorbyl 2-phosphate-6-higher fatty acid salt may transpose to position 3 over time.

Consequently, a trace amount of ascorbyl 3-phosphate-6-higher fatty acid salt may also be contained in the external skin preparation of the present invention even if not incorporated during production.

[0023] The external skin preparation of the present invention may also contain components normally used in external skin preparations within a range that does not impair the effects of the present invention, examples of which include carries and additives

pharmacologically acceptable for use in external skin preparations. Specific examples of such components include hydrocarbons, natural fats and oils, fatty acids, higher alcohols, alkyl glyceryl ethers, esters, silicone oils, polyvalent alcohols, monovalent lower alcohols, sugars, polymers, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants not corresponding to the aforementioned nonionic surfactants (1) and (2), natural surfactants, ultraviolet absorbers, powders, colorants, amino acids, peptides, vitamins, vitamin-like effectors, antiseptics, antioxidants, metal ion sequestering agents, moisturizers, antiphlogistics, pH adjusters, salts, organic acids, whitening agents, essential oils, terpenes, fragrances and water.

[0024]

Examples of the external skin preparation of the present invention include cosmetics and pharmaceuticals.

In the case the external skin preparation of the present invention is a cosmetic, known cosmetic raw materials can be further added at typical concentrations. For example, all cosmetic raw materials can be used that are described in the Second Edition of the Japanese Standards of Cosmetic Ingredients, Pharmaceutical and Medical Device Regulatory Science Society of Japan ed., 1984 (Yakuji Nippo Ltd.), Japanese Cosmetic Ingredients Codex, Ministry of Health, Labour and Welfare, Pharmaceutical Affairs Bureau, Inspection Section, ed., 1993 (Yakuji Nippo Ltd.), Supplement to the Japanese Cosmetic Ingredients Codex, Ministry of Health, Labour and Welfare, Pharmaceutical Affairs Bureau, Inspection Section, ed., 1993 (Yakuji Nippo Ltd.), Comprehensive Licensing Standards of Cosmetics by Category, Ministry of Health, Labour and Welfare, Pharmaceutical Affairs Bureau, Inspection Section, ed., 1993 (Yakuji Nippo Ltd.), Categorized Japanese Cosmetic Ingredients Codex, Ministry of Health, Labour and Welfare, Pharmaceutical Affairs Bureau, Inspection Section, ed., 1997 (Yakuji Nippo Ltd.) and the Encyclopedia of Chemical Raw Materials, 1991 ( ikko Chemicals Co., Ltd.).

[0025]

There are no particular limitations on the form of the external skin preparation of the present invention provided it is used by contacting the skin at the time of use, and is suitably determined corresponding to the application. Examples of forms that can be applied include a lotion, milky liquid, cream or facial pack. The external skin

preparation of the present invention demonstrates the effects thereof particularly when in the form of a lotion in which precipitation is conspicuous.

The pH of the external skin preparation of the present invention is preferably 6.5 to 7.5. If the pH is within this range, stability of the ascorbyl 2-phosphate-6-higher fatty acid salt is favorable and preparation stability is also more favorable. Furthermore, the pH refers to the value at about 25°C.

[0026]

The external skin preparation of the present invention is produced by incorporating and formulating an ascorbyl 2-phosphate-6-higher fatty acid salt, the nonionic surfactant (1) and other arbitrary components. At this time, an ascorbyl 2-phosphate derivative other than the ascorbyl 2-phosphate-6- higher fatty acid salt is preferably not incorporated.

Formulation can be carried out in accordance with ordinary methods corresponding to the form of the preparation.

[0027]

In the present invention, although the reason is not clear, incorporating the ascorbyl 2-phosphate-6-higher fatty acid salt and the nonionic surfactant (1) inhibits the occurrence of precipitation and turbidity in the external skin preparation over time.

Consequently, the external skin preparation of the present invention is useful over the entire range of external skin preparations, including cosmetics and pharmaceuticals, and is particularly useful in cosmetics.

[Examples]

[0028]

Although the following provides a more detailed explanation of the present invention based on examples thereof, the present invention is not limited to these examples.

[0029]

(Examples 1 to 6 and Comparative Examples 1 to 4)

Various components were uniformly dispersed and dissolved to obtain the compositions shown in Table 1 (units: % by mass) and then stirred to obtain lotions. The pH values (at 25°C) of the lotions immediately after preparation thereof are also shown in Table 1.

The resulting lotions were evaluated using the following procedures for the occurrence of turbidity and precipitation immediately after preparation and after storing for one month. The lotions were stored by allowing to stand undisturbed at 4°C, 25°C or 40°C. These results are also shown in Table 1.

[0030]

[1. Evaluation of Turbidity]

Turbidity was evaluated visually according to the following evaluation criteria. -: No turbidity observed

+: Slight turbidity observed, although within allowable range for use as lotion +: Turbidity clearly observed

[0031]

[2. Evaluation of Precipitation]

Precipitation was evaluated visually according to the following evaluation criteria. -: No precipitation observed

±: Slight precipitation observed, although within allowable range for use as lotion +: Precipitation clearly observed

[0032]

[Table 1]

[0033]

As indicated by the evaluation results of Table 1, Examples 1 to 6 that incorporated the nonionic surfactant (1) inhibited the occurrence of turbidity and precipitation over time over a wider temperature range and demonstrated improved lotion stability in comparison with Comparative Example 1, in which a surfactant was not incorporated, and

Comparative Examples 2 to 4, in which was incorporated a nonionic surfactant other than the nonionic surfactant (1) (POE alkyl ether not containing a POP chain).

[0034]

[Examples 7 and 8, Comparative Examples 5 to 10 and Reference Example A] Various components were uniformly dispersed and dissolved to obtain the compositions shown in Table 2 (units: % by mass) and then stirred to obtain lotions. The pH values (at 25 °C) of the lotions immediately after preparation thereof are also shown in Table 2.

The resulting lotions were evaluated in the same manner as Example 1 (evaluation of turbidity and evaluation of precipitation). Those results are also shown in Table 2.

[0035]

[Table 2]

[0036]

As indicated by the evaluation results of Table 2, Examples 7 and 8 that

incorporated the nonionic surfactant (1) inhibited the occurrence of turbidity and precipitation over time over a wider temperature range and demonstrated improved lotion stability in comparison with Comparative Examples 5 to 8 that incorporated an ester-type nonionic surfactant.

Turbidity and precipitation were prominent starting immediately after preparation in Comparative Examples 9 and 10 that incorporated an anionic surfactant and cationic surfactant.

As indicated by the results for Reference Example A, in the case of sodium ascorbyl 2-phosphate, even though it is an ascorbyl 2-phosphate derivative, differing from an ascorbyl 2-phosphate-6-higher fatty acid salt, there is little susceptibility to the occurrence of precipitation over time. In the present invention, as shown in Examples 7 and 8, the use of sodium ascorbyl 2-phosphate-6-palmitate, which is an ascorbyl

2-phosphate-6-higher fatty acid salt, allowed the obtaining of effects equal to those of Reference A, which is resistant to the occurrence of precipitation over time, as a result of combining with the nonionic surfactant (1).

[0037]

[Examples 9 to 11]

Various components were uniformly dispersed and dissolved to obtain the compositions shown in Table 3 (units: % by mass) and then stirred to obtain lotions. The pH values (at 25 °C) of the lotions immediately after preparation thereof are also shown in Table 3.

The resulting lotions were evaluated in the same manner as Example 1 (evaluation of turbidity and evaluation of precipitation). Those results are also shown in Table 3. [0038]

[Table 3]

[0039]

As indicated by the evaluation results of Table 3, in Examples 9 and 10 that incorporated nonionic surfactant (1) as well as nonionic surfactant (2), turbidity and precipitation did not occur over a wide temperature range from a low temperature (4°C) to a high temperature (40°C) and the stability of the lotion improved as compared with Example 11 that only incorporated nonionic surfactant (1).

[0040]

Among each of the components shown in Tables 1 to 3, the following components were respectively used for the nonionic surfactant (1), the nonionic surfactant (2) and other surfactants. The value of a + c and the value of b each indicate average values. HEC SE900 manufactured by Daicel Chemical Industries Ltd. was used for the hydroxyethyl cellulose, while Eco Gum T manufactured by Dainippon Sumitomo Pharma Co., Ltd. was used for the xanthan gum.

[0041]

[Nonionic Surfactant (1)]

POE(7)POP(2) decyl ether: EMALEX DAPE-0207, Nihon Emulsion Co., Ltd. POE(8)POP(4) lauryl ether: Noygen LP-100, Dai-Ichi Kogyo Seiyaku Co., Ltd. POE(10)POP(4) cetyl ether: NIKKOL PBC-33, Nikko Chemicals Co., Ltd.

POE(20)POP(8) cetyl ether: NIKKOL PBC-44, Nikko Chemicals Co., Ltd.

POE(20)POP(6) decyltetradecyl ether: NIKKOL PEN-4620, Nikko Chemicals Co.,

Ltd.

POE(30)POP(6) decyltetradecyl ether: NIKKOL PEN-4630, Nikko Chemicals Co.,

Ltd.

[0042]

[Nonionic Surfactant (2)]

HO(C₂H₄0)a-(C₃H₆0)b-(C₂H₄0)_c-H, a+c = 20, b=20: Adeka Pluronic L-44, Adeka

Corp.

[0043]

[Other Surfactants]

POE(20) cetyl ether: NIKKOL BC-20TX, Nikko Chemicals Co., Ltd.

POE(20) stearyl ether: NIKKOL BS-20, Nikko Chemicals Co., Ltd.

POE(20) decyltetradecyl ether: EMALEX 2420, Nihon Emulsion Co., Ltd.

Decaglyceryl monostearate: NIKKOL Decaglynl-SV, Nikko Chemicals Co., Ltd. POE(15) glyceryl monostearate: NIKKOL TMGS- 15, Nikko Chemicals Co., Ltd. POE(20) sorbitane monooleate: NIKKOL TO-10V, Nikko Chemicals Co., Ltd. POE(30) sorbitol tetraoleate: NIKKOL GO-430NV, Nikko Chemicals Co., Ltd. POE(3) sodium lauryl ether sulfate, 25% aqueous solution: Emal 20C, Kao Corp. Cetyl trimethyl ammonium chloride, 30% aqueous solution: Quartamin 60 W, Kao

Corp.

Claims

1. An external skin preparation containing:

an ascorbyl 2-phosphate-6-higher fatty acid salt and

a nonionic surfactant (1) represented by the following formula (1):

[wherein, R represents a linear or branched alkyl group, R represents -CH₂CH(CH₃)- or -CH(CH₃)CH2-, and m and n are each positive integers],

2. The external skin preparation according to claim 1 , wherein the average value of m in formula (1) is 6 to 12 and the average value of n is 12 to 30.

3. The external skin preparation according to claim 1 or 2, wherein the external skin preparation contains only the ascorbyl 2-phosphate-6-higher fatty acid salt as an ascorbyl 2-phosphate derivative.

4. The external skin preparation according to claim 1 , wherein the ascorbyl

2-phosphate-6-higher fatty acid salt is ascorbyl 2-phosphate-6-palmitate.

5. The external skin preparation according to claim 1 , wherein the ascorbyl

2-phosphate-6-higher fatty acid salt is an alkaline metal salt.

6. The external skin preparation according to claim 1, wherein the content of the nonionic surfactant (1) is 0.1% by mass to 10% by mass.

7. The external skin preparation according to claim 1 , wherein the content of the ascorbyl 2-phosphate-6-higher fatty acid salt is 0.01% by mass to 10% by mass.

8. The external skin preparation according to claim 1 , wherein the pH thereof is 6.5 to 7.5.

9. The external skin preparation according to claim 1, wherein the external skin preparation further contains a nonionic surfactant (2) represented by the following formula (2):

HO-(CH₂CH₂0)_a-(R³0)_b-(CH₂CH₂0)_c-H ... (2)

[wherein, R³ represents -CH₂CH(CH₃)- or -CH(CH3)CH₂-, and a, b and c are each positive integers].

10. The external skin preparation according to claim 9, wherein the average value of a + c in the formula (2) is 4 to 400, and the average value of b is 5 to 70.

11. The external skin preparation according to claim 9, wherein the content of the nonionic surfactant (2) is 0.1% by mass to 10% by mass.

12. The external skin preparation according to claim 1 , wherein the external skin preparation is a cosmetic.

13. A production method of an external skin preparation including:

R¹-0-(R²0)_m-(CH₂CH₂0)„-H ...(1)

14. The production method of an external skin preparation according to claim 13, wherein the average value of m in formula (1) is 6 to 12 and the average value of n is 12 to 30.

15. The production method of an external skin preparation according to claim 13, wherein only the ascorbyl 2-phosphate-6-higher fatty acid salt is incorporated as an ascorbyl 2-phosphate derivative.

16. The production method of an external skin preparation according to claim 13, wherein the nonionic surfactant (1) is incorporated such that the content thereof in the total amount of the external skin preparation is 0.1% by mass to 10% by mass.

17. The production method of an external skin preparation according to claim 13, wherein the ascorbyl 2-phosphate-6-higher fatty acid salt is incorporated such that the content thereof in the total amount of the external skin preparation is 0.01 % by mass to 10% by mass.

18. The production method of an external skin preparation according to claim 13, the production method further includes a step of incorporating a nonionic surfactant (2) represented by the following formula (2):

HO-(CH₂CH₂0)a-(R³0)_b-(CH₂CH₂0)_c-H ... (2)

[wherein, R³ represents -CH₂CH(CH₃)- or -CH(CH₃)CH₂-, and a, b and c are each positive integers].

19. The production method of an external skin preparation according to claim 18, wherein the nonionic surfactant (2) is incorporated such that the content thereof in the total amount of the external skin preparation is 0.1% by mass to 10% by mass.