Antiperspirant material and compositions containing it

Details Antiperspirant material and compositions containing it Antiperspirant material and compositions containing it

1999-09-02

2001-06-12

Dodson, Shelley A. (Department: 1616)

Drug, bio-affecting and body treating compositions

Anti-perspirants or perspiration deodorants

C424S066000, C424S067000, C424S068000, C424S400000, C424S401000

Reexamination Certificate

active

06245324

ABSTRACT:

The present invention relates to an antiperspirant material, a process for its preparation and to antiperspirant compositions containing it.
TECHNICAL FIELD BACKGROUND AND PRIOR ART
In a significant fraction of antiperspirant compositions, the active antiperspirant material is present in particulate form. For ease of dispensation, in many of such compositions, the active antiperspirant material is suspended or otherwise dispersed in a liquid carrier phase, often with the assistance of suspension agents or aids. If the antiperspirant material is not suitably suspended, there is a risk that it will tend to separate from the liquid carrier, for example by settling on the bottom of the container for the composition during storage or between applications. When the settled material can be readily redispersed by the user, such as by manual shaking of the applicator before use, solids settling constitutes a minor inconvenience rather than a significant problem. However, when the settling produces a compact layer which is extremely difficult or even impossible to redisperse manually, the problem attains serious proportions, because is extremely desirable to avoid or reduce the effective loss from the formulation of active antiperspirant material. Self-evidently, loss of active material during storage renders the composition non-uniform in application, with the risk that for a fraction of the time that the composition is used, it will be ineffective or insufficiently effective at controlling perspiration loss.
It has been found that advantageous skin sensory properties can be achieved by incorporating a polyglycol ether as at least part of the liquid phase in an antiperspirant composition. A practical way of suspending a particulate antiperspirant in a liquid carrier has comprised the incorporation of a suspending aid, often inorganic such as a clay. However, it has further been found that when the carrier comprises a polyglycol ether, the ability of the clay or like suspending agent to suspend or re-suspend the particulate antiperspirant material in the carrier liquid is significantly impaired.
It is known to surface treat particulate inorganic substances in other fields of activity, specifically pigments and sunscreens, but for other purposes. Thus, for example, titanium dioxide pigments are surface treated in GB-A-1602428 with esters or amines and this affects the rate at which films containing the pigment dry. In EP-A-0559319, metallic oxide particles, especially titanium dioxide and zinc oxide particles are surface coated to aid their suspension in aqueous emulsions. This is not relevant to predominantly anhydrous compositions of the present invention. Similarly in U.S. Pat. No. 5,573,753, dispersions of surface treated particulate titanium oxide and zinc oxide in an aqueous emulsion are described. In U.S. Pat. No. 4,318,843 (EP-A-0021262) there is described the surface treatment of inorganic pigments of which TiO
2
is exemplified in order to improve its gloss and distribution in lacquer bindings. In U.S. Pat. No. 5,776,440, the effectiveness of metallic oxide to screen out UV-radiation when applied topically is enhanced by coated them with a wide range of organic compounds. The treatment of TiO2 is exemplified.
It is an object of the present invention to ameliorate or overcome one or more of the problems or disadvantages indicated hereinabove.
SUMMARY OF THE INVENTION
According to the present invention there is provided a particulate antiperspirant material which has been surface treated with an alkanolamine.
According to related aspect of the present invention there is provided a process for surface treating a particulate antiperspirant material characterised by bringing the antiperspirant material into contact with an alkanolamine in a liquid medium and maintaining contact until at least some alkanolamine is deposited on or absorbed in the surface of the antiperspirant material.
By surface treating the particulate antiperspirant material with the alkanolamine, it has been found that the resultant particulate material shows a reduced tendency to separate from a liquid carrier phase containing a polyglycol ether and a suspending agent.
Surface treating and surface treatment herein indicates that the surface treatment agent is in intimate contact with the surface or outer layer of the substrate material, i.e. the antiperspirant material, and may either be deposited on the surface, for example forming a layer or coating of the treatment agent on the substrate surface or at least a fraction of the agent may be absorbed within the outer layer of the substrate.
In a further aspect of the present invention, there is provided an antiperspirant composition comprising an antiperspirant material and a liquid phase comprising a carrier characterised in that the antiperspirant material comprises a particulate antiperspirant material which has been surface treated with an alkanolamine.
Herein, comprising in the context of a composition indicates that the composition may contain one or more further ingredients in addition to those specified within the composition.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides a particulate surface treated antiperspirant active and antiperspirant compositions containing the same, and especially compositions containing a polyglycol ether and a suspending agent.
Antiperspirant Material
The antiperspirant material can comprise any particulate material which is capable of reducing or preventing perspiration when it is applied topically to human skin. The present invention is directed to antiperspirant actives which when applied topically penetrate the eccrine gland and are subsequently deposited therein, blocking its duct and preventing egress of sweat. Accordingly, such material commonly comprises an astringent salt. The antiperspirant often comprises aluminium, zirconium, mixed aluminium/zirconium salts, and titanium salts, including both inorganic salts and organic salts and complexes. Preferred astringent salts include aluminium, zirconium and aluminium/zirconium halides and halohydrate salts, such as chlorohydrates. Some especially preferred halohydrate salts comprise activated aluminium chlorohydrates such as those described in EP-A-6739 (Unilever NV et al) and other actives are described in EP-A-28853, the contents of both specifications being incorporated herein by reference. It will be recognised that metallic oxides derived from aluminium, zirconium, titanium or zinc are considered not to be antiperspirants.
Astringent aluminium salts include aluminium chloride and aluminium halohydrates having the general formula Al
2
(OH)
x
Q
y
.XH
2
O in which Q represents chlorine, bromine or iodine, x is from 2 to 5 and x+y=6, x and y being either integers or non-integers and X being from 0 to 6.
A range of zirconium salts which can be employed in antiperspirant compositions herein is represented by the following empirical general formula: ZrO(OH)
2n−nz
B
z
in which z is an integer or non-integer in the range of from 0.9 to 2.0, n is the valency of B, 2−nZ is at least 0 and B is selected from the group consisting of halides, including chloride, sulphamate, sulphate and mixtures thereof.
It will be recognised that the above-identified formulae for aluminium and zirconium salts are greatly simplified and encompass compounds having co-ordinated and/or bound water in various quantities as well as polymeric species and mixtures and complexes.
Antiperspirant complexes based on the above-mentioned astringent salts are known and employable in the present invention. By way of example, complexes of aluminium, zirconium and aminoacids such as glycine are disclosed in U.S. Pat. No. 3,792,068 (Luedders et al). Certain of those complexes or complexes with related structures are commonly called ZAG in the literature. One desirable class of complexes which exhibit structure like ZAG comprise aluminium chlorohydrate, including that satisfying the formula Al(OH)
5
Cl.2H
2
O complexed with aminoacids or other complexing agents. A preferred class

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