Antiperspirant formulations

Details Antiperspirant formulations Antiperspirant formulations

2002-07-10

2003-11-11

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Anti-perspirants or perspiration deodorants

C424S066000, C424S068000, C424S400000, C424S401000

Reexamination Certificate

active

06645475

ABSTRACT:

The present invention relates to antiperspirant formulations and in particular to anhydrous soft solid formulations.
BACKGROUND AND PRIOR ART
Humans perspire over much of the body, but there are some areas where perspiration is more intense or noticeable after a period of time, such as in the underarm, possibly on account of molecular transformations of excretions from the apocrine, endocrine or sebaceous glands. Antiperspirant formulations are commonly accepted in many societies as a means to obviate or prevent wet patches on human skin or on clothing in contact with the skin. Their application can also reduce body odour generation. The underarm (axilla) is one area where antiperspirant formulations are normally applied.
Antiperspirant formulations are available for application via several different types of dispenser. These include non-contact dispensers such as aerosols or squeeze spray dispensers or contact dispensers such a roll-on or cream or firm stick dispenser. The formulations dispensed include both hydrous or anhydrous compositions. One class of formulation which is favoured by various consumers in some parts of the world comprises anhydrous creams, sometimes called soft solids, in which a particulate antiperspirant active material, commonly an aluminum or aluminum/zirconium astringent salt or complex, is suspended in a water-immiscible carrier fluid which is structured by incorporation of sufficient structurant to enable the formulation to be dispensed under mild pressure through one or more apertures in the dispensing head of a container and remain in place on the dispensing head until applied to the skin, eg to the axilla.
Anhydrous creams can incorporate a range of antiperspirant active salts, but it is often considered advantageous to employ salts containing both aluminum and zirconium, on account of their measured effectiveness at controlling perspiration when topically applied to human skin. Such creams conveniently employ a wax or mixture of waxes to impart structure to the carrier fluid, in part at least because such structurants are readily available and cost effective. The carrier fluid in commercially available anhydrous cream products normally comprises a volatile silicone oil such as a volatile linear or cyclomethicone, by virtue of the desirable overall combination of properties of such materials.
However, one of the problems that can be present in anhydrous creams which are applied topically to human skin is the observation of visible white deposits, not only on the skin, but also when the formulation is transferred onto clothing. Transfer can arise by direct contact or by fractions of the applied formulation being dislodged from the skin surface, for example by brushing, and falling under the influence of gravity onto clothing that is directly underneath. These white marks can be found on clothing adjacent to armpits or in the region of the hips. Such marks are significantly disliked by consumers, who find them relatively difficult to remove except by washing. Washing is usually not convenient if the mark is observed when the wearer is in public, and the common method of mark removal by rubbing with a dampened handkerchief is hindered by the hydrophobic nature of the structurant and carrier fluid.
Some manufacturers have proposed to add so called masking agents into cream formulations to reduce the visibility of the white marks, and to some extent this can be successful, especially for a period shortly after application of the formulation. However, it has now been observed that the effectiveness of masking agents can diminish with time, and this is particularly noticeable in respect of creams that contain aluminum/zirconium astringent salts and those which are structured using waxes. This can mean, for example, that a mark becomes more visible as the day progresses, if it is not removed quickly. Of course, it can be difficult to recognize immediately that a mark has occurred, when it exhibits only very low visible deposits initially. Visible deposits have been the subject of consumer complaints, not only to the brand owner, but the problem has also been raised on TV consumer programmes. Wax structurants are desirable in other ways; for example, they are readily available and formulations produced using them can have attractive sensory properties, but the problem of increased visibility of deposits during leave-on is one that remains.
Accordingly, it is an object of the present invention to devise wax-structured cream formulations that have a reduced tendency to exhibit visible marks during leave-on over an extended period of time.
SUMMARY OF THE INVENTION
According to the present invention there is provided an anhydrous antiperspirant cream composition comprising
a) a particulate aluminum/zirconium astringent salt in an amount of from 5 to 30% by weight;
b) a wax in an amount of from 4 to 20% by weight, said wax comprising an aliphatic ester or monohydric alcohol wax; and
c) a water-immiscible carrier having a refractive index that is less than 0.1 below the refractive index of the aluminum/zirconium astringent salt and comprising an aromatic ester having a melting point of below 25° C. and/or a non-volatile silicone oil having a refractive index of at least 1.5 in an amount of from 45 to 80% by weight.
For an anhydrous antiperspirant cream composition herein, i.e. a soft solid, the hardness H will generally be from 0.003 to 0.5 N/mm
2
, as measured by sphere indentation. Frequently, such hardness will be from 0.005 up to 0.1 N/mm
2
.
Anhydrous herein indicates in the context of a cream composition that the composition does not comprise a liquid aqueous phase.
By formulating in accordance with the summary of the invention, it is possible to prepare anhydrous antiperspirant compositions in which an aluminum zirconium astringent salt suspended in a water-immiscible carrier fluid that is solidified by a wax exhibits improved resistance to the development of visible deposits over a period of time when exposed to the atmosphere after topical application. This accordingly ameliorates problems of white deposits appearing on the body or clothing several hours after contact with an antiperspirant formulation.
In a related second aspect of the present invention there is provided a process for preparing an anhydrous antiperspirant formulation in the form of a cream comprising the steps of:
i) introducing into a mixing vessel a carrier fluid having a refractive index that is less than 0.1 below the refractive index of the aluminum/zirconium astringent salt and comprising an aromatic ester having a melting point of below 25° C. and/or a non-volatile silicone oil having a refractive index of at least 1.5 in an amount of from 50 to 80% by weight;
ii) introducing into the vessel a wax in an amount of from 4 to 20% by weight said wax comprising an aliphatic ester or monohydric alcohol wax;
iii) heating the non-polymeric wax until it melts or is miscible with the carrier fluid;
iv) introducing into the carrier fluid or mixture of carrier fluid and wax a particulate aluminum/zirconium astringent salt in an amount of from 5 to 30% by weight at a temperature above the normal solidification temperature of the formulation and;
v) introducing the composition into a dispenser whilst the composition is fluid.
In a further aspect of the present invention, there is provided a method for controlling or preventing perspiration by topically applying to the human body, and especially to the axilla a composition according to the first aspect described hereinabove.
DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention relates to anhydrous cream formulations containing particulate antiperspirants in which the tendency for visible deposits to develop over time in wax-structured compositions is ameliorated or suppressed.
The antiperspirant active comprises suspended aluminum zirconium astringent salts.
Aluminum halohydrates employable herein are usually defined by the general formula Al
2
(OH)
x
Q
y
.wH
2
O in which Q represents chlorine, bromine or iodine, x is variable from 2 t

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