Ester-terminated poly(ester-amide) in personal care products

#The invention relates to gelling agents, and in particular to gellants for low polarity liquids such as hydrocarbons, and the use thereof in commercial products, e.g., personal care products.

#Personal care products generally contain one or more active ingredients within a carrier formulation. While the active ingredient(s) determine the ultimate performance properties of the product, the carrier formulation is equally critical to the commercial success of the product. The rheology of the carrier (also referred to as the “base”) largely determines the flow properties of the product, and the flow properties largely determine the manner in which the consumer will apply or use the product.

#For example, aluminum chlorohydrate and aluminum-zirconium tetrachlorohydrex-Gly are metal salts that are commonly used as active ingredients in deodorant and antiperspirant products. Consumers have shown a preference for applying deodorant from a stick form. Thus, the carrier in a stick-form deodorant must be a relatively hard substance, and waxy fatty alcohol such as stearyl alcohol has been used as the carrier in these products. As another example, the active ingredient in a lipstick is the colorant. A lipstick should not be as hard as a stick deodorant, but of course must maintain its shape when undisturbed at room temperature. A blend of wax and oil is known to provide a consistency that is well-suited as a carrier for a lipstick. As a final example, shampoo desirably has a viscosity greater than water, and when the active ingredient(s) in a shampoo does not have a sufficiently high viscosity, a somewhat viscous carrier material is desirably included in the shampoo formulation.

#The present invention is directed to ester-terminated poly(ester-amides) (ETPEA) and a method of preparing a resinous composition (hereinafter, simply “a resin”) comprising, in whole or part, EPTEA. A resin comprising ETPEA (an “ETPEA resin”) is useful as a gelling agent for hydrocarbons and other low polarity liquids, where the resultant gels are useful components in, for example, personal care products, candles, lubricants, inks, corrosion inhibitors, cosmetic formulations and other products that can benefit from gel-like character.

#In one aspect, the present invention provides a resin composition prepared by reacting components comprising dibasic acid, diamine, polyol and monoalcohol, wherein at least 50 equivalent percent of the dibasic acid comprises polymerized fatty acid; and at least 50 equivalent percent of the diamine comprises ethylene diamine. Before further describing this resin, and other aspects of the present invention, the reactants useful in preparing the resin will be described.

#The dibasic acid is an organic molecule containing two carboxylic acid groups or reactive equivalents thereof. A preferred dibasic acid is polymerized fatty acid, and in particular the dimer acid component of polymerized fatty acid. Polymerized fatty acid is typically a mixture of structures, including dimer acid and trimer acid, where individual dimer acids may be saturated, unsaturated, cyclic, acyclic, etc. Polymerized fatty acid as used to form the resin of the invention is a well known material of commerce, and thus need not be described in great detail. Polymerized fatty acid is typically formed by heating long-chain unsaturated fatty acids, e.g., C18 monocarboxylic acids, to about 200-250° C. in the presence of a clay catalyst in order that the fatty acids polymerize. The product typically comprises dimer acid, i.e., C36 dicarboxylic acid formed by dimerization of the fatty acid, and trimer acid, i.e., C54 tricarboxylic acid formed by trimerization of the fatty acid. A more detailed discussion of fatty acid polymerization may be found in, e.g., U.S. Pat. No. 3,157,681 and Naval Stores—Production, Chemistry and Utilization, D. F. Zinkel and J. Russell (eds.), Pulp. Chem. Assoc. Inc., 1989, Chapter 23.