Mixed esters of dicarboxylic acids for use as pigment dispersants

#The present invention relates to novel mixed esters of polypropoxylated fatty alcohols and monohydric fatty alcohols with dicarboxylic fatty acids. These compounds exhibit unique pigment dispersion, emolliency and gloss-imparting properties. The fatty mixed esters of the present invention are particularly useful in the formulation of make-ups and other pigmented products, lotions, lipsticks, cold creams, skin moisturizers, sunscreen lotions, topical pharmaceutical products and cleansing creams. The present invention further relates to topical preparations incorporating the fatty mixed esters of the present invention.

#A diverse range of formulations useful in personal care and pharmaceutical applications utilize inorganic pigments and other micronized inorganic oxides, such as physical sunscreen ingredients. Typically, these finely divided particulate products are dispersed within formulations by mixing, using either low-shear or high-shear methods. In order to make stable, cosmetically acceptable products, uniform dispersions must be produced, with all particles wetted out and which remain in suspension over a period of time without settling, jelling or agglomerating. Producing such stable suspensions has proved to be a challenge, although some successes have been achieved.

#For example, U.S. Pat. No. 5,116,604 to Fogel describes the use of neopentanoate esters, in particular isoarchidyl neopentanoate, as cosmetic emollients for sunscreen products. U.S. Pat. No. 5,716,602 to Ulck describes sunscreens formulated to include a water resistance agent and an insect repellent. One form has in it an aqueous emulsion DEET, a sunscreen agent, an anionic surfactant, an alkylated PVP, and octyldodecyl neopentanoate. Both Fogel and Ulck use Octyldodecyl Neopentanoate.

#The novel compounds of this invention are particularly useful in wetting and dispersing pigments, including such pigments as metallic oxides. The novel mixed esters of this invention are produced by the reaction of propoxylated fatty alcohols and monohydric fatty alcohols with dicarboxylic fatty acids. Preferably, the propoxylated fatty alcohols have a carbon chain length between 4 and 24 carbon atoms and a degree of propoxylation between 3 and 30, and most preferably between 3 and 15 units of propylene oxide.

#It is additionally preferred that the diacid used in this invention is an aliphatic diacid having a carbon chain length between 4 and 40. The preferred fatty alcohols are chosen from a group having a carbon chain length between 12 and 24.

#A preferred aliphatic diacid is dilinoleic acid and preferred propoxylated fatty alcohols are myristyl alcohol and butyloctanol. Preferred monohydric fatty alcohols are octyldodecanol and isostearyl alcohol.