Drug – bio-affecting and body treating compositions – Topical body preparation containing solid synthetic organic... – Skin cosmetic coating
Reexamination Certificate
2001-06-05
2002-12-31
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Topical body preparation containing solid synthetic organic...
Skin cosmetic coating
C424S059000, C424S060000, C424S070100, C424S401000, C514S972000
Reexamination Certificate
active
06500415
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a cosmetic composition, particularly a cosmetic composition having an ultraviolet shielding ability. More specifically, the present invention relates to a titanium oxide- or zinc oxide-containing cosmetic composition capable of maintaining the emulsion stability for a long period of time by virtue of thickening of a polymer having a carboxyl group in the side chain.
BACKGROUND ART
In cosmetic compositions having an ultraviolet shielding ability, an organic compound-based ultraviolet absorber or an inorganic compound-based ultraviolet shielding agent is blended.
The organic compound-based ultraviolet absorber has a problem of instability due to its decomposition property and therefore, an inorganic compound-based ultraviolet shielding agent is recently used in many cases. In particular, titanium oxide or zinc oxide is generally used.
The preparation form of the cosmetic composition having an ultraviolet shielding ability includes various shapes such as solubilized form, emulsion form (W/O type, O/W type, W/O/W), powder form and gel form. In the case of an O/W form or gel form, a thickening polymer having a carboxyl group in the side chain is preferably used as a thickener so as to increase stability of the preparation form.
Specific examples of the thickening polymer having a carboxyl group in the side chain include carboxyvinyl polymer, carboxymethyl cellulose, carboxymethyl starch, poly(sodium acrylate), alginic acid propylene glycol ester and alginic acid salt. Among these, carboxyvinyl polymer is used widely.
The carboxyvinyl polymer is characterized and advantageous in that high thickening stability can be obtained with a low concentration, that reproducibility which cannot be realized by natural polymers can be attained, that the temperature stability and microorganism resistance are high, that the pH and viscosity which can be used have a wide range, and that good use property is provided at the application to skin. Therefore, the carboxyvinyl polymer is being widely used in cosmetic materials. For example, JP-A-08-505624 (WO94/15580) discloses an oil-in-water emulsion composition comprising a fine pigment particle having the surface treated to be hydrophobic, and a carboxylic acid polymer thickener. JP-A-09-151110 discloses alkyl (meth)acrylate polymer as a thickener for a liquid cosmetic containing an inorganic powder such as titanium oxide.
In the case where the carboxyvinyl polymer is used in combination with titanium oxide or zinc oxide in an ultraviolet shielding cosmetic composition, the titanium oxide or zinc oxide used in combination for enhancing the ultraviolet shielding ability is likely formed into microfine particles and the resulting increase in the surface activity of titanium oxide or zinc oxide (catalytic action) causes deterioration of carboxyvinyl polymer. The surface activity can be suppressed to a certain extent by surface treatment with silica, alumina or the like, however, photocatalytic deterioration of carboxyvinyl polymer cannot be satisfactorily suppressed by conventional surface treatments. Accordingly, reduction of viscosity takes place in the gel-form preparation and separation or creaming in the emulsion-form preparation.
The carboxyvinyl polymer deteriorates in the preparation form stability due to the effect of metal ion, because the hydration degree of polymer is reduced by the reaction between metal ion and carboxyl group and therefore, the viscosity decreases. In conventional production of surface-treated titanium oxide or zinc oxide, the surface treatment uses precipitation of inorganic metal oxide from sodium silicate or sodium aluminate and since sodium ion remains, polyvalent ion such as calcium, magnesium and iron is contained as impurities in many cases.
Furthermore, conventional surface-treated zinc oxide is insufficient in the film formation and therefore, zinc ion is eluted accompanying the dissolution of zinc oxide. As a result, when conventional surface-treated titanium oxide or zinc oxide is used in combination with carboxyvinyl polymer, the viscosity decreases along the elution of ion and the preparation form stability disadvantageously deteriorates.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide an ultraviolet shielding cosmetic composition containing titanium oxide or zinc oxide, which can maintain the preparation (emulsion or gel) form stability for a long period of time by the thickening of carboxyvinyl polymer.
As a result of extensive investigations to attain the above-described object, the present inventors have found that a cosmetic composition having desired properties can be obtained when silica-coated titanium oxide or zinc oxide coated with a certain dense silica film is blended in combination with a polymer having a carboxyl group in the side chain. The present invention has been accomplished based on this finding.
More specifically, the present invention relates to the following cosmetic composition, silica-coated titanium oxide and/or silica-coated zinc oxide used for the cosmetic composition, and method for producing the same.
[1] A cosmetic composition comprising titanium oxide coated with one or both of silica and alumina or zinc oxide coated with one or both of silica and alumina, and a thickening polymer having a carboxyl group in the side chain.
[2] The cosmetic composition as described in [1] above, wherein the thickening polymer having a carboxyl group in the side chain is at least one polymer selected from a group consisting of carboxyvinyl polymer, carboxymethyl cellulose, carboxymethyl starch, poly(sodium acrylate), alginic acid propylene glycol ester and alginic acid salt.
[3] The cosmetic composition as described in [2] above, wherein the thickening polymer having a carboxyl group in the side chain is carboxyvinyl polymer.
[4] The cosmetic composition as described in [3] above, wherein when titanium oxide coated with one or both of silica and alumina or zinc oxide coated with one or both of silica and alumina is dispersed by 10% by mass in an aqueous solution containing 0.133% by mass of a carboxyvinyl polymer, the viscosity after the passing of 100 hours is 50% or more of the initial viscosity.
[5] The cosmetic composition as described in [4] above, wherein when titanium oxide coated with one or both of silica and alumina is dispersed by 10* by mass in an aqueous solution containing 0.133% by mass of a carboxyvinyl polymer, the viscosity after the passing of 100 hours is 70% or more of the initial viscosity.
[6] The cosmetic composition as described in [4] above, wherein when zinc oxide coated with one or both of silica and alumina is dispersed by 10% by mass in an aqueous solution containing 0.133% by mass of a carboxyvinyl polymer, the viscosity after the passing of 100 hours is 60% or more of the initial viscosity.
[7] The cosmetic composition as described in [1] above, which comprises silica-coated titanium oxide or silica-coated zinc oxide coated with a dense silica film having a film thickness of 0.1 to 100 nm and a refractive index of 1.435 or more.
[8] The cosmetic composition as described in [11] above, wherein the photocatalytic activity of the silica-coated titanium oxide or silica-coated zinc oxide determined by the tetralin auto-oxidation method is 60 Pa/min or less.
[9] The cosmetic composition as described in [1] above, wherein the silica-coated titanium oxide or silica-coated zinc oxide has a primary particle size of 5 to 200 nm.
[10] The cosmetic composition as described in [1] above, wherein the ratio I of absorption peak intensity at 1,150 to 1,250 cm
−1
to absorption peak intensity at 1,000 to 1,100 cm
−1
on the infrared absorption spectrum (I=I
1
/I
2
, wherein I
1
, is absorption peak intensity at 1,150 to 1,250 cm
−1
and I
2
is absorption peak intensity at 1,000 to 1,100 cm
&m
Futami Junko
Ishii Nobuaki
Takama Michihiro
Wada Kouichi
Fubara Blessing
Page Thurman K.
Showa Denko K.K.
Sughrue & Mion, PLLC
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