Patent Application
20070286939
The present invention relates to a novel class of alkoxylated phosphate esters made by reacting shea butter with polyoxyethylene glycol or polyoxypropylene glycol or mixtures thereof followed by phosphation of the resulting phosphate ester. The invention is also directed to a process for using the shea butter alkoxylated phosphate esters in personal care applications. Preferably, mild processing is employed both at the time of harvesting and initial extraction and during subsequent preparation of alkoxylate derivatives. In so doing, materials containing unexpectedly high amounts of active ingredients, particularly highly desired unsaponifiables, are produced.
Shea butter (and MPSB) alkoxylated phosphate esters of the present invention conform to the following structure:
Rx—C(O)—O—(CH2CH2O)a—(CH2CH(CH3)O)b—(CH2CH2O)c—P(O)—(O−M+)3
wherein
Rx, is shea butter or, preferably mild-processed shea butter, which comprises
a, b and c are independently integers ranging from 1 to 20;
M is selected from the group consisting of H, Na and K.
Another aspect of the present invention is a process for delivering antioxidants to the skin and hair by applying thereto a finished topical product comprising an effective amount of an alkoxylated phosphate ester made by an esterification reaction of shea butter, or preferably MPSB, and polyoxyalkylene glycol thereof that conforms to the following structure:
Rx—C(O)—O—(CH2CH2O)a—(CH2CH(CH3)O)b—(CH2CH2O)c—P(O)—(O−M+)3
wherein
Rx is derived from shea butter, preferably mild-processed shea butter, which comprises
a, b and c are independently integers ranging from 1 to 20; and
M is selected from the group consisting of H, Na and K.
By “finished topical product” is meant a cream, lotion, gel, foam, ointment, paste, emulsion, suspension, dispersion, solution, or similar topically-applied carrier or delivery system known to those of skill in the art.
Shea butter can be prepared by standard extraction techniques known to those of skill in the art. For example, U.S. Pat. No. 6,552,208, the disclosure of which is incorporated herein by reference, describes several methods for processing shea butter. Suitable extraction vehicles may include, but are not limited to, ethanol, methanol, ethyl acetate, acetone, chloroform and water, or any other solvent and water.
Sterols comprise about 20% of the unsaponifiables in shea butter. More particularly, the sterols comprise: cholesterol (from about 1% to about 3%); alpha-spinasterol (from about 1% to about 4%); delta-7-stigmasterol (from about 40% to about 44%); delta-7-avenasterol (from about 38% to about 41%). The remaining constituents of the unsaponifiables (about 80%) include other highly desirable active compounds including tocopherol, karitin, cinamic acid esters, alpha and beta amyrin and phenolics.
Phenolic compounds are natural products composed of one or more aromatic benzene rings with one or more hydroxyl group. They are a class of natural products that possess antioxidant and free radical scavenging properties. Among the phenolics in the unsaponifiables of mild-processed shea butter include gallic acid, gallocatchin, catechin, epigallocatechin gallate, epicatechin, gallocatechin gallate, gallocatechin gallate and quercetin.
In a preferred aspect of the present invention, shea butter is mild-processed; it is extracted using a hydrocarbon-free solvent system and its polyoxyalkylene ester derivatives of the present invention are made under mild processing conditions. At the time of harvesting and initial extraction ground-up kernels are boiled in water under mild conditions as described in the example below. The oil phase is then separated from the water phase by decanting. This process provides a yellow, solid wax rich in unsaponifiables. By wax is meant a material obtained by boiling in water under ambient conditions, decanted and filtered.
MPSB is made according to following procedure: 500.0 grams of the nut form the Shea Butter tree are cracked into small pieces and placed into a one-liter vat of water. The water is then heated to 100° C. As the temperature increases, an oil phase develops on the surface of the water. The temperature is held for about 2 hours, after which the oil is decanted and passed through filter paper. The resulting butter is mild-processed shea butter according to the present invention. It is rich in unsaponifiable (from about 7% to about 15% by weight) and may be used in making the MPSB polyoxyalkylene glycol esters of the present invention.
Mild processing according to this aspect of the present invention may be contrasted with separation using solvents and high temperature treatment with high pressure steam. While the latter processes result in what some may describe as a “more pure” triglyceride, unsaponifiables, and the benefits derived therefrom, are lost. Vacuum distillation which strips off the desirable components is also to be avoided in processing MPSB of the present invention. By processing shea butter under mild conditions, materials comprising from about 5% to about 15% by weight of unsaponifiables can be produced.
Polyoxyalkylene Glycols
Polyoxyalkylene glycols are items of commerce and conform to the following structure:
H—(OCH2CH2)a—(CH2CH(CH3)O)b—(CH2CH2O)c—H
wherein, a, b and c are independently integers ranging from 1 to 20. Illustrative, but not limiting, examples of polyoxyalkylene glycols which may in preparing the esters of the present invention are set out below:
It will be clearly understood that by polyoxyalkylene glycol compounds is meant three different classes of compounds. Polyoxyethylene glycols are compounds in which “b” is zero; polyoxypropylene glycols are compounds in which “a” and “c” are zero and polyoxyalkylene glycols compounds in which “a” and/or “c” are not zero and “b” is not zero.
The following examples are illustrative of the alkoxylation step in creating the compounds of the present invention. The components and specific ingredients are presented as being typical, and various modifications can be derived in view of the foregoing disclosure within the scope of the invention. All percentages, ratios and proportions herein are by weight, unless otherwise specified. All temperatures are in degrees Celsius unless otherwise specified.
Polyoxyalkylene glycols as described in Examples 1-6 are reacted with shea butter, and more preferably MPSB, as follows: To 145.0 grams of shea butter (or MPSB) are added the number of grams of polyoxyalkylene glycols in Examples 7-18. Using a reflux condenser, the temperature of the mass is raised to 180° C.-190° C. The mass is held within this temperature range for 10 hours. Nothing is distilled off during this time, and the reaction mass becomes hazy. The reaction mass is cooled, glycerin separates off and is removed from the bottom. The products of Example 7-18 may be used in formulating finished cosmetic and personal care products without additional purification.
Phosphation Reagents
Polyphosphoric acid (CAS No. 008017-16-1) and P2O5 (CAS No. 1314-56-3) are articles of commerce well-known to persons of skill in the art. These reagents are reacted with the above-described alkoxylated shea butter (and MPSB) to produce the compounds of the present invention.
The following examples are further illustrative of the phosphation step in creating the compounds of the present invention. 49 grams of polyphosphoric acid are added to the specified grams of the polyoxyalkylene glycol shea butter ester of Examples 7-18. The reaction mass is stirred well until homogeneous then heated to, 90° C. for about 4 to 5 hours.
Alternatively, as illustrated below, 24 grams P2O5 are added under good agitation to the specified grams of polyoxyalkylene glycol shea butter ester of Examples 7-18. The reaction mass is stirred well until homogeneous then heated to, 90° C. for about 4 to 5 hours.
The compounds of the present invention are effective surface active agents that provide emmoliency as well as mild detergency. They are well tolerated by the skin and eye and deliver antioxidants to the skin.
While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth hereinabove but rather that the claims be construed as encompassing all the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those skilled in the art to which the invention pertains.
