Drug – bio-affecting and body treating compositions – Face or body powders for grooming – adorning – or absorbing
Reexamination Certificate
2000-12-13
2003-11-25
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Face or body powders for grooming, adorning, or absorbing
C424S063000
Reexamination Certificate
active
06652844
ABSTRACT:
The invention relates to a solid product based on hydrophobic mineral powder, particularly talcum or mica, having a predetermined characteristic shape that lends itself to handling, especially in the form of a stick. In particular, it concerns a solid product for cosmetic or hygienic use, enabling talcum or mica to be deposited on the skin by contact and gentle rubbing. The invention also relates to a manufacturing method enabling such a product to be obtained with a rigidity and cohesion compatible with its being used without risk of breaking or crumbling.
Talcum is often used in the form of a powder as an active ingredient in cosmetics owing to its emollient properties. The deposit of talcum or the thin film formed protects the skin from redness and irritation, protects the epidermis from rubbing and absorbs excess perspiration. This very old application is carried out by dusting powder on to the surface to be treated and, in practice, is somewhat inconvenient: dusting creates a cloud of powder of greater or lesser size, depending on how fine the talcum is, which pollutes the atmosphere, soils surfaces other than the surface to be treated and leads to material losses.
Furthermore, talcum or mica powder is incorporated in numerous cosmetic formulations as a filler. This mineral powder is generally pressed with active ingredients and fatty binders of the paraffin, lanolin, glycerin or stearate types to obtain a friable paste, which is placed in a pot or tub, generally to be applied using a brush (particularly where make-up products are concerned). In these products, the talcum or mica acts as a filler, which is essentially used to dilute the active ingredient or ingredients into which it is incorporated. This paste contained in the pot or tub has no inherent strength, but, taking into account its packaging, weak cohesion and high friability are acceptable, which enables proportions of talcum or mica of the order of 40 to 50% to be provided, exceptionally reaching 80% in certain products (WO 97/04737 relating to a composition “with high levels of talcum”; “Handbook of Cosmetic Science and Technology”; 1
st
edition, 1993, p. 134-145, U.S. Pat. No. 4,837,011, EP 0 587 415, WO 98.30195). A high proportion of talcum or mica combined with a relatively low proportion of fatty binder limit the “greasy” effect created by the product when it is applied.
Furthermore, sticks exist for lips (lipsticks or coating sticks) comprising active ingredients and fatty binders, which enable a finishing or protective fatty layer to be deposited on the lips. These sticks have sufficient strength to enable them to be handled but do not generally contain talcum or mica (which are known to have unfavorable effects on particle cohesion). The “Handbook of Cosmetic Science and Technology” cited above provides the most common formulations of this type of sticks (p. 147-155). However, it should be noted that the journal “Cosmetics and Toiletries, April 1992” gives, on p. 95 and 96, a formulation for a stick for lips containing a small percentage of mica (5%) or talcum (3.65%).
Mineral powders of talcum or mica, and hydrophobic mineral powders more generally, are therefore known to agglomerate with difficulty and to give very friable cakes as soon as the proportion of mineral powder in the product becomes high; this explains why, for more than a century, talcum has been used in the form of a powder when it is intended to be applied alone (or in by far the greatest proportion) as an active cosmetic or hygienic ingredient. For several decades, the development of the numerous formulations referred to above, including talcum or mica as a filler, have only confirmed this teaching, since products with a high load of talcum or mica are products without any inherent cohesion, necessarily contained in pots, tubs or other containers to be applied using an instrument such as a brush, and the very rare stick products containing talcum include very little of it.
It can be noted that certain documents propose the coating of particles of hydrophobic powder to modify their surface properties (U.S. Pat. No. 5,023,075, WO 96.30448); however, it does not appear that the object of this treatment is to make solid products; at any rate, such techniques do not constitute a solution to the problem of the invention, since the characteristics of the initial natural powder are modified.
The present invention proposes the provision of a solid product based on hydrophobic mineral powder, such as talcum or mica, having a rigid shape that enables it to be handled so that a mineral compound can be applied directly by contact with the surface to be treated: the invention aims to avoid in this way the disadvanitages associated with the treatments mentioned above by the dusting of powder.
The object of the invention is in particular to provide a product in the form of a stick or other shape capable of being handled, which is essentially made up of a mineral powder based on talcum or mica (i.e. in which the other components represent less than 20 wt. % of the product) and which benefits from the following features:
inherent cohesion and strength compatible with use by contact without the solid product breaking or crumbling,
good distribution of talcum or mica by contact with the surface to be treated,
dry impression on application, with no greasy effect.
Another object of the invention is to avoid the so-called “polishing” effect, which consists in a reduction in the distribution after several applications.
To this end, the method according to the invention for making such a solid product with a characteristic shape and cohesion making it capable of being handled is characterized in that the hydrophobic mineral powder, particularly mineral powder based on talcum or mica, is impregnated using a volatile liquid binder in proportions by weight such that the proportion of volatile liquid binder is at least equal to 5% and the proportion of mineral powder at least equal to 80%, and in that the resulting impregnated powder is pressed so as to shape it and provide it with cohesion ensuring the rigidity of the product.
“Mineral powder based on talcum or mica” means a powder in which talcum or mica, or a mixture of the two, represents at least 75 wt. % of the powder (generally more than 85%, preferably more than 95%, or even 100%), any other components being mineral components such as kaolin, carbonate etc., or possibly organic, such as starch etc. “Talcum” means either the mineral hydrous magnesium silicate or the mineral chlorite (hydrous magnesium and aluminum silicate), or a mixture of the two. “Mica” means aluminous micas such as sericite, muscovite, magnesium micas such as phlogopite, and aluminous or magnesium illites derived from the above minerals by variable substitutions of Al for Si on the one hand, and of Fe for Al or Mg on the other hand.
“Volatile liquid binder” means a binder that is liquid at normal temperature and pressure having a volatility, defined by DIN standard 53249, such that the loss of weight is greater than or equal to 30% after 100 minutes at 25° C. This type of volatile binder always has a viscosity of less than 50 centipoises.
The term “press” means any operation for compressing grains of powder, particularly the operation of pressing in any press system, extrusion operation etc., the resulting solid product then being removed from the press to be packaged according to its shape and the intended application.
Tests have shown that it was possible to make, using the method of the invention, products based on hydrophobic mineral powder, such as talcum or mica powder, having rigidity and cohesion compatible with good shape stability and handling without breaking or crumbling (during manufacture when removing from the mold and during use), while giving a dry impression when applied to the skin (no “greasy” effect): talcum can thus be used by contact to serve as an active ingredient under the same conditions as traditional talcum powder products capable of being dusted. On contact with the surface to be treated, the product se
Arseguel Didier
Goffinet Pierre Charles
Riviere Brigitte
Joynes Robert M.
Page Thurman K.
Talc de Luzenac
Young & Thompson
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