Oil-in-Water Emulsion Cosmetic

Abstract

The present invention has the purpose of providing an oil-in-water emulsion cosmetic that contains a high quantity of an ultraviolet absorbing agent and an ultraviolet scattering agent in the oil phase and achieves a high SPF, while simultaneously having a Distinctive fresh feeling in use when applied to the skin. The present invention provides an oil-in-water emulsion cosmetic characterized by comprising (A) 0.05 to 1% by mass of a hydrophobically modified alkyl cellulose; (B) 5 to 40% by mass of an oil component; (C) 2.5 to 30% by mass of an ultraviolet scattering agent having a hydrophobic surface; and (D) a water phase thickener having low salinity tolerance; wherein the (C) ultraviolet scattering agent is dispersed in the oil phase.

Description

TECHNICAL FIELD[0001]The present invention relates to an oil-in-water emulsion cosmetic, particularly to a sunscreen cosmetic, containing an ultraviolet absorbing agent and an ultraviolet scattering agent to provide a high ultraviolet protection capability (SPF) in addition to providing a distinctively fresh feeling in use.BACKGROUND ART[0002]An oil-in-water emulsion cosmetic is widely used as a base material to provide a fresh feeling in use compared to a water-in-oil emulsion. However, when powders, particularly powders that have been hydrophobically treated, are blended in their inner phase (oil phase), the emulsion system tends to become unstable.[0003]As one method of stabilizing the emulsion system, a water-soluble thickener has been applied to increase viscosity of the outer phase (water phase) of the oil-in-water base material. However, it is problematic that viscosity decrease of the water phase due to an elution of ions from the hydrophobically treated powder blended in th...

AI Technical Summary

Benefits of technology

The present invention is about an oil-in-water emulsion cosmetic that uses a hydrophobically modified alkyl cellulose and a thickener in the water phase. This results in a high sun protection factor (SPF) while keeping the oil content low. The cosmetic also has a distinctive fresh feeling when applied to the skin. The use of a thickener with low salinity tolerance is conventionally avoided to prevent affecting emulsion stability, but this present invention utilizes it to achieve a smooth and comfortable application. The oil-in-water emulsion cosmetic contains high amounts of ultraviolet absorbing and scattering agents. The hydrophobically modified alkyl cellulose used in this invention is produced by reacting a water-soluble cellulose ether with a long-chain alkyl group. The method involves bringing the cellulose ether into contact with a compound for introducing a long-chain alkyl group. Overall, the oil-in-water emulsion cosmetic provides high stability and a unique fresh feel when applied to the skin.

Problems solved by technology

However, when powders, particularly powders that have been hydrophobically treated, are blended in their inner phase (oil phase), the emulsion system tends to become unstable.

However, it is problematic that viscosity decrease of the water phase due to an elution of ions from the hydrophobically treated powder blended in the inner phase (oil phase) and so forth takes place and results in destabilization and causing stickiness (Patent Document 1).

However, (volatile) non-polar oils such as low-viscosity hydrocarbon oils or silicone oils are commonly used as dispersion media that are added for powder dispersion, and it was known that the use of polar oils in the inner phase increases the amount of distribution into the oil phase of hydrophilic groups in the surfactant and thereby makes emulsification difficult.

In other words, in order to achieve high ultraviolet protection capability, a high-polarity ultraviolet absorbing agent, and in some cases, a polar oil to serve as the solvent thereof, must be added, while also necessitating the inclusion of a non-polar oil as a dispersion medium for stably emulsifying the oil phase containing an ultraviolet scattering agent, so it was extremely difficult to suppress the total oil content while maintaining a high ultraviolet protection capability.

However, in these cosmetics, at least half of the oil phase (inner phase) is constituted by a non-polar oil, so there are limits to the suppression of the total oil content.

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