The invention relates to certain new silicone modified proteins and to their use in cosmetics and toiletries.
The use of proteins, their hydrolysates and chemically modified derivatives in cosmetic formulations to provide performance and conditioning benefits to skin and hair is well known. These benefits derive mainly from the film-forming and moisture-retentive properties exhibited by such "cosmetic proteins" together with their substantivity (ability to adsorb and resist elution with water) to hair and skin.
Proteins from a variety of animal and vegetable sources can be used and the relative film-forming and moisture-retentive properties can be controlled by the selection of a particular protein and its average molecular weight. It is also possible to chemically modify proteins to modify their behavior and functionality. Examples include esterification of carboxyl groups, acylation of amino groups and quaternization of amino groups.
Benefits claimed for proteins and their derivatives in the conditioning of hair include improved combability, gloss, moisture control, body and reduced "fly-away". For skin, benefits include moisturization, skin-firming/smoothing, improved feel and anti-irritation effect.
Another category of conditioning agents which have established a significant role in cosmetics products are silicones. "Silicone" is a general term for a range of chemicals with different behavior and effects but characterized by the "silicon-oxygen silicone" chain. Polydimethylsiloxanes (dimethicones) exhibit low solubility in water, low surface tension and antifoam behavior and have been found to confer gloss and lubricity to hair and a soft feel to skin. To overcome the limitations of water insolubility, silicone glycols (dimethicone polyols) have been developed which also exhibit foaming behavior and confer lubricity to keratin substrates.
In order to provide substantivity to hair, amino functional silicones (e.g. amodimethycones) have been developed which are also capable of polymerizing on the hair, but are water insoluble.
From the foregoing it will be understood that "proteins" and "silicones" represent two distinct categories of valuable conditioning agents for skin and hair with different physical properties and functional benefits.
The possibility of developing modified proteins which would have some properties characteristic of silicones (e.g. increased lubricity) or alternatively silicones with some of the benefits of proteins (greater water solubility and substantivity), offers potential for the formulation of cosmetic products with novel properties.
Products which are mixtures of silicones and proteins have been offered but it will be obvious to those skilled in the art of cosmetic formulations that mixtures will not provide the desired improvement in solubility characteristics or substantivity and lubricity for rinse-off systems.
EP 0295 983 assigned to Exsymol SAM, describes products formed by the condensation of a silane, silanol or siloxane with the carboxylic acid group of amino acids. The products, which contain only one silicon atom per molecule, are claimed to have useful therapeutic and cosmetic effects.