Drug – bio-affecting and body treating compositions – Anti-perspirants or perspiration deodorants
Reexamination Certificate
2000-06-12
2001-06-26
Dodson, Shelley A. (Department: 1616)
Drug, bio-affecting and body treating compositions
Anti-perspirants or perspiration deodorants
C424S066000, C424S068000, C424S400000, C424S401000
Reexamination Certificate
active
06251377
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to cosmetic compositions for application to human skin. Significant forms of the invention are concerned with antiperspirant compositions for application to human skin, especially the axilla. However, the invention can also be applied to other forms of cosmetic composition.
BACKGROUND OF THE INVENTION AND SUMMARY OF PRIOR ART
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. A significant example of such cosmetic compositions are antiperspirant compositions which are widely used in order to enable their users to avoid or minimise wet patches on their skin, especially in axillary regions.
Antiperspirant formulations have been provided with a range of different product forms. One of these is a so-called “stick” which is usually a bar of an apparently firm solid material held within a dispensing container and which retains its structural integrity and shape whilst being applied. When a portion of the stick is drawn across the skin surface a film of the stick composition is transferred to the skin surface. Although the stick has the appearance of a solid article capable of retaining its own shape for a period of time, the material usually has a structured liquid phase so that a film of the composition is readily transferred from the stick to another surface upon contact.
Antiperspirant sticks can be divided into three categories. Suspension sticks contain a particulate antiperspirant active material suspended in a structured carrier liquid phase. Emulsion sticks normally have a hydrophilic phase containing the antiperspirant active in solution, this phase forming an emulsion with a second, more hydrophobic, liquid phase. The continuous phase of the emulsion is structured. Solution sticks typically have the antiperspirant active dissolved in a structured liquid phase which may be a mixture of water and a water-miscible organic solvent.
Other types of cosmetic composition can also be provided in the form of a stick and again the stick may be a structured solution, emulsion or suspension. Examples of cosmetic compositions which are, or can be, marketed in a stick form are lipsticks, lip salves and eyebrow pencils.
There is substantial literature on the structuring of cosmetic compositions.
Conventionally, many sticks have been structured using naturally-occurring or synthetic waxy materials. Examples of these include those fatty alcohols which are solid at room temperature, such as stearyl alcohol, and hydrocarbon waxes or silicone waxes. Such materials are widely available, and by suitable selection of the materials themselves and their concentrations in the formulation, it is possible to obtain either a soft solid or a firm solid. Examples of wax-structured sticks are described in an article in Cosmetics and Toiletries, 1990, Vol 105, P75-78 and in U.S. Pat. Nos. 5,169,626 and 4,725,432. However, fatty alcohol or wax structured sticks tend to leave visible white deposits on application to human skin, and 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.
Some alternative structurants have been proposed. The term “gellant” is often employed instead of “structurant”. For example, the use of dibenzylidene sorbitol (DBS) or derivatives thereof as gellant has been proposed in a number of publications such as EP-A-512770, WO 92/19222, U.S. Pat. No. 4,954,333, U.S. Pat. No. 4,822,602 and U.S. Pat. No. 4,725,430.
In WO 97/11678 to Helene Curtis, Inc, there is described the use of lanosterol as a gellant to make soft gels, sometimes in conjunction with a starch hydrolyzate derivative for antiperspirant compositions. All the formulation examples contain both a volatile silicone oil and an organic solvent which is a silicon-free compound or mixture of compounds.
In WO 98/34588 to Lancaster Group GmbH, there is described the use of lanosterol as a gellant for oil-based cosmetic compositions, containing a cosmetic active material, of which one listed material is a deodorant, though not exemplified. The exemplified compositions contain hydrocarbon oils.
SUMMARY OF THE INVENTION
We have observed that if stick products are made using lanosterol as gellant for an oil phase which is a mixture of silicone oil and silicon-free organic solvent, the resulting sticks do not remain stable during storage. Crystals of lanosterol grow and form crystalline lumps in the stick which mar its appearance and give a gritty feel. The process can lead to loss of strength of the stick and leakage of solvent.
Surprisingly we have found that much better storage stability can be achieved if the oil phase is substantially free of any silicon-free organic compound which is liquid at 20° C.
According to a first aspect of the present invention there is provided a composition of matter suitable for cosmetic use having a continuous phase which comprises water-immiscible liquid carrier and a structurant therein wherein the structurant comprises lanosterol and the water-immiscible liquid carrier comprises one or more silicone oils, with not more than 3% (by weight of the liquid) of any silicon-free organic compounds which are liquid at 20° C. dissolved therein.
Preferably the content of any such silicon-free liquid organic compounds is not more than 2%, preferably not more than 1% (by weight of the liquid) and more preferably they are absent, so that the carrier liquid consists solely of silicone oil.
The lanosterol serves as a structuring agent for the liquid carrier which consists very largely or exclusively of silicone oil.
When used in a sufficient amount, which is likely to be less than 15% of the total composition, it is able to structure this liquid into a gel with sufficient rigidity to sustain its own shape.
Lanosterol may be the only structurant present. If any other structurant is used jointly with lanosterol the amount of it is likely to be less than the amount (by weight) of lanosterol. The amount of structurant is likely to be not over 15% of the formulation, better not over 10% or 12%.
Without being bound to any specific theory or explanation, it is believed that the lanosterol forms a network of interconnected strands extending throughout the carrier liquid phase. Upon heating the gel to a temperature referred to as the gel melting temperature, the strands of structurant dissolve and the liquid becomes more mobile.
The structurant water-immiscible carrier liquid may be the continuous phase of a composition with a dispersed solid phase suspended therein. It is especially envisaged that the composition will be an antiperspirant and the dispersed solid will be a particulate antiperspirant active.
Another, less preferred, possibility is that the carrier liquid is the continuous phase of an emulsion. Then the dispersed liquid phase may be a solution of antiperspirant active in water or other hydrophilic solvent.
A composition of this invention will generally be marketed in a container by means of which it can be applied at time of use. This container may be of conventional type.
A second aspect of the invention therefore provides a cosmetic product comprising a dispensing container having an aperture for delivery of the contents of the container, means for urging the contents of the container to the said aperture, and a composition of the first aspect of the invention in the container. Suitably, the aperture is an open end.
The compositions of this invention can be produced by conventional processes for making suspension, or as the case may be, emulsion solids.
Thus, according to a third aspect of the present invention there is provided a process for the production of a cosmetic composition comprising, not necessarily in any order, the steps of
incorporating lanosterol as structurant into a water-immiscible liquid carrier which comprises one or more silicone oils with not more than 3% (by weight of the liqu
Boxer Matthew
Dodson Shelley A.
Unilever Home & Personal Care USA , division of Conopco, Inc.
LandOfFree
Cosmetic compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cosmetic compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cosmetic compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2473912