Gels are used for a variety of products having cosmetic, medicinal, veternary, paint, printing and other applications. In many such applications, thixotropic gels are preferred, having the property of being semisolid colloids (gels) when undisturbed, but flowing readily when shaken, stirred, sheared or otherwise subjected to stress. Such gels typically are prepared by mixing a solvent, cosolvent, gelling agent (also called gellant) and optionally additional oils and waxes, active ingredients, preservatives, pigments or other coloring matter and other additives under conditions in which the mixture is either a liquid solution or a suspension. The mixture is then cooled causing a gel to form, accompanied in some instances by polymerization or other reaction between various substituents. The final gel is a semi-solid suspension. It should be appreciated, however, that only some gels so formed are stable and exhibit good thixotropy, with many gels so formed either separating with time (being too thin) or not yielding to shear (being too thick). It should also be appreciated that many mixtures of components fail to form or retain a colloidal state such that droplets of one or more components (typically an oil or wax) separates upon cooling so as to form an unstable or grainy material which is unsatisfactory for many applications.
In the production of such gels, particularly in cosmetic gels such as lipsticks and deordorant and antiperspirant sticks, the gelling agent is frequently carnauba wax, candellela wax, beeswax or other organically derived waxes which contain a mixture of paraffins, fatty esters, fatty alcohols and sometimes fatty acids. Such gelling agents are often inconsistent from one batch to the next, requiring extra care in formulating cosmetic products. Such waxes also have relatively low melting points such that gels having such waxes become liquid and flow when warmed to about 50.degree. C. or above. Often gellants such as paraffin, insect and microcrystalline waxes suffer from the same defects, as do the synthetic organophillic bentonite gellants, such as those referred to by the tradename Quarternium-18 Hectorite, used by the cosmetic industry.
Thus a need exists for a gelling agent of consistent quality which can form stable, compatible thixotropic gels with common solvents, cosolvents and other additives of the type now used in thixotropic gels.
USPTO Backgrounds
USPTO Backgrounds