Colored cosmetic sticks of improved hardness

#1. Field of the Invention

#The invention relates to a colored cosmetic stick of improved rigidity for use especially as a lipstick.

#2. The Related Art

#The manufacture of a reproducibly rigid colored cosmetic stick requires provision of a wax which is free from any C.sub.12 -C.sub.60 fatty acid, especially fatty monocarboxylic acid, an impurity normally present in the natural waxes. This impurity may be counteracted through esterification with a molar equivalent or more of a C.sub.1 -C.sub.60 mono or polyhydric alcohol. Particularly preferred are the C.sub.1 -C.sub.60 monohydric alcohols. Illustrative alcohols useful herein include methanol, ethanol, lauryl alcohol, palmitic alcohol and combinations thereof.

#The esterification process involves combining the natural wax with from 0.5 to 20% of the alcohol in a vessel under agitation at a temperature of anywhere from about 40.degree. C. to about 250.degree. C., preferably from about 80.degree. C. to about 150.degree. C.

#Advantageously, a vacuum is applied to the vessel to remove water vapor formed in the esterification. An effective amount of a Lewis acid catalyst may be employed, for instance, a mineral acid (e.g. sulfuric or hydrochloric acid), an organic acid (e.g. toluene sulfonic acid) or an inorganic substance such as boron trifluoride etherate.