Oil-in-water emulsion cosmetic composition and method for producing the same

Abstract

To provide an oil-in-water emulsion cosmetic composition obtained by using a polyglycerin fatty acid ester as a surfactant, which has high stability against temperature and is excellent in tactile sensation, and a method for producing the same, the present invention provides an oil-in-water emulsion cosmetic composition, wherein the composition comprises 1) a polyglycerin fatty acid ester, as a surfactant, having a hydroxyl value of 450 to 700, a fatty acid residue having 16 to 18 carbon atoms accounting for 50 to 100% by mass of all constituent fatty acid residues, the polymerization degree of glycerin having specific distribution, 2) an oily component, and 3) water.

Description

TECHNICAL FIELD [0001] The present invention relates to an oil-in-water emulsion cosmetic composition comprising, as components, 1) a polyglycerin fatty acid ester as a surfactant (or an emulsifier), 2) an oily component, and 3) water, and a method for producing the same and, more particularly, to an oil-in-water emulsion cosmetic composition obtained by using a polyglycerin fatty acid ester, which is excellent in emulsion stability such as stability under various temperature conditions (hereinafter referred to as “stability against temperature”) and is also excellent in tactile sensation, and a method for producing the same. BACKGROUND ART [0002] In oil-in-water emulsion cosmetic compositions such as ointment, cream, milky lotion and serum, a polyoxyethylene-based surfactant has been used. Examples of the polyoxyethylene-based surfactant include polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters and polyoxyethylene alkyl ethers. [0003] These polyoxyet...

AI Technical Summary

Benefits of technology

[0019] An object to be achieved by the present invention is to provide an oil-in-water emulsion cosmetic composition obtained by using a polyglycerin fatty acid ester as a surfactant, which has high stability against temperature and is excellent in tactile sensation, and a method for producing the same. The stability against temperature in the present invention refers to high temperature stability, low temperature stability, stability against temperature variation, and stability against high temperature shaking.

[0033] The oil-in-water emulsion cosmetic composition of the present invention is excellent in emulsion stability, that is, stability against temperature such as 1) high temperature stability (for example, emulsion stability at 50° C.), 2) low temperature stability, 3) stability against temperature variation, or 4) stability against high temperature shaking, and is also excellent in tactile sensation. That is, the oil-in-water emulsion cosmetic composition of the present invention exerts the following effects: 1) texture in appearance, 2) free from greasy feel when applied to the skin, 3) excellent transparent feel, and 4) good compatibility (rapidly compatible with skin).

Problems solved by technology

However, it has been known that this polyoxyethylene-based surfactant has some fear for safety to the human body and high concentration of the polyoxyethylene-based surfactant causes irritation of the skin.

To the contrary, when an oil-in-water emulsion cosmetic composition having poor emulsion stability is exposed under severe conditions during a circulation process or use by a consumer, there arises a problem that thickening, solidification, separation and aggregation may occur and thus commercial value may be lost.

There also arises a problem that an emulsion cosmetic composition is thickened or solidified by temperature variation during storage of the product or shaking during transportation, thus resulting in separation and aggregation.

As described above, the oil-in-water emulsion cosmetic composition obtained by using the polyglycerin fatty acid ester had a problem how emulsion stability is enhanced.

However, according to this method, the functions of the surfactant do not efficiently exert on interface between oil and water.

With the increase of the level of quality required to cosmetics, various formulations in a cosmetic composition have been developed and it becomes difficult to decrease the particle size of emulsified particles.

There is a limit in the development of the emulsifying machine, and the development of a new emulsification method was made.

Therefore, the product is sensorily restricted, that is, appearance and formulation are restricted and it requires it takes a long time to previously study due to a phase diagram.

With respect to load in the production, there were drawbacks that a cosmetic composition can not be produced according to the formulation in which a polyhydric alcohol gel must be produced and long time is required to emulsify, and also it is impossible to add in the amount enough to uniformly disperse by an agitator an oil phase before emulsification and a polyhydric alcohol, that is, the formulation in which the oil phase and polyhydric alcohol are contained in a small amount.

However, it has been known that this polyoxyethylene-based surfactant has some fear for safety to the human body and high concentration of the polyoxyethylene-based surfactant causes irritation of the skin, as described above.

The oil-in-water emulsion cosmetic composition obtained by this method using this polyoxyethylene-based surfactant has a drawback such as poor tactile sensation.

However, the method except for these dispersion emulsification methods has a problem such as restriction of the product and a problem in the production.

To the contrary, when the self-emulsification method is applied to an oil-in-water emulsion cosmetic composition obtained by using a polyglycerin fatty acid ester, a polyglycerin fatty acid ester is not easily dissolved in an oily component, and if it is dissolved in the oily component, the composition is not self-emulsified and is emulsified only by a mechanical force in a homomixer.

Therefore, the resulting oil-in-water emulsion cosmetic composition had poor emulsion stability.

Therefore, the oil-in-water emulsion cosmetic composition produced by the dispersion emulsification method employing self-emulsification using a polyglycerin fatty acid ester was not circulated in the market.

The diglycerin monofatty acid ester having self emulsification characteristics is circulated but has poor self emulsification characteristics, and thus a satisfactory emulsion has never been obtained.