Antiperspirant formulations

Details Antiperspirant formulations Antiperspirant formulations

2001-08-02

2002-03-26

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Anti-perspirants or perspiration deodorants

C424S066000, C424S068000, C424S400000, C424S401000, C424SDIG005

Reexamination Certificate

active

06361766

ABSTRACT:

The present application relates to antiperspirant formulations, and in particular to antiperspirant stick formulations.
BACKGROUND AND PRIOR ART
Topically applied antiperspirant compositions are in widespread use throughout much of the world, in order to enable their users to avoid or minimise visible wet patches on their skin, especially in axillary regions. Antiperspirant formulations containing astringent metal salts such as aluminium or zirconium salts commonly act also as deodorants. Antiperspirant formulations have been produced or proposed for use in several physical forms, such as solids, gels, soft solids, creams, lotions and particulate mixtures and these forms can be applied using a range of different dispensers, including aerosol, roll-on, pump spray, sticks, and barrel dispensers, in accordance with the individual preferences of consumers. In some parts of the world, solid formulations in stick form are especially popular, the stick usually being dispensed from a barrel provided with means to expose the stick above the barrel.
Herein, the term stick indicates a bar of solid material which retains its integrity whilst being applied, i.e. a firm stick and which is commonly, though not exclusively, housed within a dispensing container which hitherto is conveniently in the shape of a barrel. When a portion of a firm stick is drawn across the skin surface, a film of the stick composition is transferred onto the skin surface. Although the stick has the appearance of a solid article, the material forming the stick usually comprises a structured liquid phase such that a film of the material is readily transferred onto another surface such as axillary skin upon contact under pressure.
There are typically three classes of firm antiperspirant sticks, namely suspension sticks, emulsion sticks and solution sticks. Suspension sticks contain a particulate antiperspirant active material suspended in a structured carrier. Emulsion sticks normally comprise an emulsion of an oil phase and a hydrophilic phase containing the antiperspirant active in solution, the continuous phase being structured. In some emulsion sticks, the continuous phase is an oil phase. In solution sticks, the antiperspirant is typically dissolved in the liquid carrier phase which is structured. The liquid phase can comprise water and/or a water-miscible organic solvent. The three categories can be applied to sticks of both firm and soft solids compositions.
Conventionally, many suspension sticks have been structured using naturally-occurring or synthetic waxes, of which typical examples include stearyl alcohol, hydrocarbon waxes, waxes of plant or animal origin or their synthetic analogues or derivatives or silicone waxes. Waxes are widely available, and by suitable selection of the waxes themselves and their concentrations in the formulation can effectively obtain either a soft solid or a firm solid. Thus for example, wax-structured sticks are described in an article in Cosmetics and Toiletries, 1990, vol. 105, p75-78. However, many conventional fatty alcohol or other wax structured sticks tend to leave visible white deposits on application to human skin, and likewise, visible deposits can also be transferred onto clothing by physical contact with the skin. Such visible deposits are disliked by a significant, and in some countries growing, proportion of consumers of antiperspirants, be they on the skin or on clothing. Accordingly, the antiperspirant industry, including the instant inventors, is continuing devoting considerable time and resources to finding means to ameliorate or overcome customer perceived whiteness deposits. In countries where both traditional and low whitening antiperspirant stick products are available, sales of the low whitening formulations have grown relative to traditional formulations.
Patents and patent documents relevant to this field of invention include:
U.S. Pat. No. 3,255,082;
Barton et al;
U.S. Pat. No. 3,986,203;
Spitzer et al;
U.S. Pat. No. 4,083,956,
Shelton;
EP-A-0,028,853,
Beckmeyer et al;
U.S. Pat. No. 4,425,328,
Nabial et al;
U.S. Pat. No. 4,265,878,
Keil;
U.S. Pat. No. 4,229,432,
Geria;
U.S. Pat. No. 4,724,139,
Palinczar
U.S. Pat. No. 4,985,238,
Tanner et;
U.S. Pat. No. 5,486,347,
Callaghan et al and
U.S. Pat. No. 6,068,518,
Bianchi et al.
Antiperspirant formulations remain on the skin for considerable periods of time after application, for example many hours before the axilla or other part of the body to which the antiperspirant has been applied is washed. In that respect they differ significantly from many other personal care formulations such as washing or cleansing formulations which are applied and almost immediately removed. Accordingly, all non-volatile components present in the antiperspirant formulations remain on the skin, including not only non-volatile anti-perspirant actives, but also non-volatile components of any carrier fluid which is employed. Such non-volatile components not only remain on the skin, but likewise remain available for transfer onto clothing which comes into contact with the skin. Carrier liquid components can assist in the transfer of solids suspended therein.
Since their introduction, volatile silicone fluids have been widely accepted within the antiperspirants industry as carrier fluids for antiperspirant solids, and commonly are either thickened to form a cream or structured to form a solid in order to suspend particulate antiperspirant materials. Volatile silicone oils have proven to be very popular, on account of their combination of beneficial properties, so that in many or most of the common commercial anhydrous suspension stick formulations, such oils constitute the principal proportion of the carrier fluid. One or more other oils, such as non-volatile silicone oils or non-volatile non-silicone emollient oils are often included or proposed for inclusion in patent specifications in minor amounts in firm stick suspended antiperspirant formulations, and indeed together commonly constitute no more than a minor fraction of the carrier fluid.
Although volatile silicone oils enable the antiperspirant formulations to exhibit many desirable properties, there are two consequences of employing them as the principal component of the carrier fluid, namely that such antiperspirant formulations tend to exhibit comparatively high visible whiteness when they are topically applied and also the visible whiteness of such formulations tends to increase further with the passage of time. Without being bound to any theory, it is believed that increased visible whiteness arises from evaporation of the volatile silicones, thereby exposing those formulation components such as particulate antiperspirant actives and/or structurant which contribute to visible whiteness. These observations are of relevance, because users look carefully at where they are applying antiperspirant formulations, and they often remain on the skin for extended periods of time.
However, it is no simple matter to reformulate antiperspirant formulations with alternative oils. Whilst many oils have been accepted within the industry as minor components of a volatile-silicone-based carrier fluid, the very properties which have rendered them suitable to be considered suitable as emollients have been thought to render them unsuitable as the principal carrier oil. These properties include a propensity to oiliness or greasiness in the resultant product, when present in a large proportion.
A number of attempts have been made already to address the problems of selecting carrier fluids for antiperspirant formulations. Several patent specifications offer lists of emollient oils for incorporation in carrier fluids, in some instances for creams, such as in EP-A-388110 and WO-A-98/51272 and in other instances for sticks, such as U.S. Pat. No. 5,833,964. These specifications classify as similar, materials which the investigation resulting in the present invention show to be significantly different. Accordingly, although such specifications assert that they provide formulation exhibiting low visible de

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