Cosmetic compositions

Abstract

An improved process for the preparation of cosmetic formulations containing a cosmetic active and a continuous phase comprising a water-immiscible liquid carrier, that are structured by a cyclo dipeptide (CDP) having the general formula in which R1 and / or R2, which may be the same or preferably different, each represents a hydrocarbon or alkylene ester group and the other may alternatively represent hydrogen, which employs a monohydric alcohol having a melting point of below 30° C. and a boiling point of greater than 100° C. and a cosmetic active material optionally together with at least one water-immiscible liquid carrier oil to assist in the dissolution of the structurant and modify the gelling temperature of the resultant mixture. Preferably, the CDP is dissolved in the monohydric alcohol and optionally up to half the water-immiscible oil prior to being mixed with the remaining ingredients of the composition.

Description

[0001] The present invention relates to cosmetic compositions for application to human skin, to the preparation and use of such compositions and to structurants for incorporation in such compositions and their preparation.BACKGROUND OF THE INVENTION AND SUMMARY OF PRIOR ART[0002] A wide variety of cosmetic compositions for application to human skin make use of a structured liquid carrier to deliver colour or some other active material to the surface of the skin. Significant examples of such cosmetic compositions include antiperspirant or deodorant compositions which are widely used in order to enable their users to avoid or minimise wet patches on their skin, especially in axillary regions or to control or prevent the emission of malodours, which could otherwise arise when the user perspires. Other examples of cosmetic compositions include lip sticks.[0003] Although structuring is a term that has often been employed in respect of materials which structure a carrier liquid, various o...

AI Technical Summary

Benefits of technology

[0018] Applicants have now found that the processing of cosmetic formulations employing a cyclodipeptide as a gelling agent for a cosmetic oil carrier can be improved by employing a class of materials that can act as a solvent for the cyclo dipeptides and which is miscible with the cosmetic oils.

[0026] By employing a monohydric alcohol having the physical attributes identified above as an essential component of the continuous carrier for the cosmetic active, it is possible to render it easier to obtain structured compositions using the selected structurant, and can also or alternatively enable compositions to be obtained in which the problem of undesirable discoloration can be reduced or eliminated. The incorporation of the selected alcohol can lower the temperature at which the desired concentration of structurant dissolves when the carrier also comprises a water-immiscible oil and can also increase the concentration of the cyclic dipeptide which can dissolve in the carrier phase, and furthermore can ameliorate or avoid the problem of the mixture becoming immobile at an excessively high temperature.

[0039] In a fourth aspect of the present invention, the cosmetic active comprises an antiperspirant or deodorant active. Thus, according to the fourth aspect, there is provided a cosmetic method for preventing or reducing perspiration or odour formation on human skin comprising topically applying to the skin a composition comprising a cosmetic active, a water-immiscible liquid carrier and a structurant compound as defined above in the first aspect in which the cosmetic active is an antiperspirant or deodorant active.

Problems solved by technology

Sticks which are structured with fatty alcohol tend to leave visible white deposits on application to human skin; moreover the deposits can also transfer onto clothing when it comes into contact with the skin and the wearer can, for example, find white marks at the armhole of the sleeveless garment.

Cosmetic formulations containing such gellants can suffer from a number of disadvantages, including instability in the presence of acidic antiperspirants, and comparatively high processing temperatures needed in the production of sticks.

Although cyclo dipeptides can be extremely effective gellants for cosmetic oils, the manufacture of compositions in which they are employed as gellants is subject to a number of practical constraints or difficulties.

First, it is often difficult to incorporate sufficient cyclic dipeptide into the cosmetic oil to enable it to structure or gel the oil to the extent that would be preferred by the manufacturer.

That is because the cyclic dipeptides are relatively poorly soluble in commonly employed cosmetic oils, such as volatile or even non-volatile silicone oils.

Furthermore, and unsurprisingly, the gelling temperature of a solution of such a gellant in such oils increases as its concentration in solution increases.

The net consequence of its gelation behaviour is that if enough cyclic dipeptide is present to cause the resultant product to have a preferred firmness at ambient temperature, the gelation temperature of the cyclic dipeptide in the oil is undesirably high, commonly in the region of or in excess of 100.degree. C.

At such temperatures, many cosmetic oils can evaporate or become discoloured and if the formulation is in the form of an emulsion stick, water evaporation renders the preparation of accurate composition extremely difficult and at worst impossible.

Moreover, increased processing temperatures can also result in degradation or discoloration of some cyclic dipeptides themselves.

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