Cosmetic powders are currently available in loose and pressed form. The majority of these powders, face powder, blusher, eye shadow, etc., are used in pressed form. This form of the product is very practical since it is easy to carry along and can be used whenever needed for touching up. The desirable properties of a pressed powder are: easy powder release without dustiness, good skin adhesion, and a strong cake which does not crumble, break, or cake up. In order to achieve all of these characteristics, the present pressed powder formulations contain a blend of several ingredients, each chosen for their specific quality.
The major constituents of a regular shaded pressed powder are talc and color; all other ingredients being used to achieve compressibility. Binding is a special property inherent to pressed powder formulation. Most powder constituents found in formulations are not "binding" in themselves and therefore other agents such as metallic stearates, kaolin, and fatty materials are used as additives to insure proper adhesion and compressibility. Fatty materials, such as mineral oil or fatty alcohols, are used in liquid form to aid in binding, improve adhesion to the skin, and reduce cake dustiness.
In frosted products, mica and titanium dioxide coated mica (pearlescent materials) are the major powder constituents. In order to compress these materials, a large portion of about 20 to 40 percent of a composition is added. Such large amounts of non-pearlescent ingredients reduced the "frosty" effect of the product.
With current methods, manufacturing of a pressed powder is long and tedious. It involves blending of all dry powder ingredients, wetting the blend with the liquid fatty material and can lead to subsequent balling up of the powder. In order to break up the powder balls and achieve a uniform liquid distribution within the powder, it must then go through a micropulverization process. The inability to hold a shape after compression may vary with the chemical origin of the binding agent and the percentage utilized in the pressed powder formulation. A great many such formulations are possible. See for example, De Navarre, The Chemistry and Manufacture of Cosmetics, Vol. 4 Continental Press, Fla. 1974.
In the past many methods of aggregating inherently non-cohesive powders were used. For example, Ornfeldt, in U.S. Pat. No. 1,996,168 discloses a jelly-like substance which might be used. 1-5% of beeswax or synthetic wax and a small amount of soap are combined in melted form with mineral oil and heated. After cooling the mixture, powdery materials such as talc are added. The jelly-like substance will increase the surface cohesiveness of the powder and keep it from dusting. No mention is made of compressing this powdery product, nor is it likely that this would constitute a suitable method for aggregating a powder which is to remain substantially dry, such as face powder.
Picker, in U.S. Pat. No. 1,707,684 employs olive oil as a waterproof binder for powder in loose form. Olive oil might be used as a cosmetic additive for its emolient properties, however, it does have a tendency to turn rancid. Moreover, it is doubtful that olive oil would provide sufficient cohesiveness to form a strong cake of powder.
Kole in U.S. Pat. No. 3,300,387 discloses a pressed powder consisting of an anti-perspirant coated with 5-15% of a water soluble wax-like material such as PEG and its methoxy derivatives mixed with a powder base and an oily binder such as mineral oil, lanolin, vegetable oils and isopropyl esters of fatty acids. The pressed powders of U.S. Pat. No. 3,800,034 to Kircher et al. contain binders such as gum, cellulose derivatives, gelatin, lignin, PVP, PVA and a complex magnesium silicate and lubricants such as metal stearates, liquid paraffin, fatty alcohols, fatty acids and oils. Harris et al., in U.S. Pat. No. 4,279,890 use metal stearates as binder and lubricant in pressed powders. Prevention of cracking in pressed powders was provided in U.S. Pat. No. 4,305,931 to Kawano et al. by incorporating a hydroxypropyl-etherified glycolipid ester.
Despite the advances noted above, manufacturing of a pressed powder with conventional ingredients is a long involved multi-step process wherein the ingredients are handled repeatedly in order to achieve the desired properties. This explains, in part the high cost of certain cosmetics and their failure to meet performance criteria. Anti-perspirant sticks can be produced by combining active particulate ingredients such as aluminum chlorohydrate with a low melting point wax and melting the mixture so that an anti-perspirant stick can be formed from the hot wax. This is an expensive process in terms of energy consumption and results in a wet, greasy, wax-like product which is unpleasing to the touch. This process is frequently used to produce anti-perspirant sticks because a suitable compressing aid which would allow the dry manufacture of many such products is unavailable.