Hand cleanser

Details Hand cleanser Hand cleanser

2000-05-08

2002-08-13

Page, Thurman K. (Department: 1615)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Wearing apparel, fabric, or cloth

C424S401000, C424S400000, C424S443000

Reexamination Certificate

active

06432429

ABSTRACT:

The present invention relates to a cleanser, in particular a so-called “waterless” hand cleanser, and an abrasive hand cleansing article impregnated with such a cleanser.
Conventional hand cleansing formulations contain solvents and/or surfactants capable of solubilising or emulsifying soils present on the skin's surface. The cleansing power of such formulations is however limited, particularly when dealing with the removal of various heavy, ingrained soils such as may be encountered by those working in industry.
A number of hand cleansers currently being used are in the form of a gel which may contain both polar and non-polar ingredients blended together to achieve removal of a variety of soils from the surface of the skin. These often contain abrasive particles which scour the skin surface to aid in the removal of embedded soils. One disadvantage associated with such gels is the need to wash-off the gel residue or excess cleanser from the-skin following use. This means that the operation of hand cleansing takes longer and, in the case of industrial hand cleansing, this ultimately increases costs.
A further disadvantage associated with the use of gels is that, depending on the formulation, these have a tendency to remove the skin's natural protective lipids, particularly when the cleanser is used repeatedly, leaving the skin with no protection against dehydration once the gel residue has been rinsed off. This is a particular problem in areas of low humidity.
One solution to this problem has been presented in the form of so-called “waterless” formulations which do not require the addition of water or moisture to be activated. In particular these do not require rinsing of the hands with water after use.
A “waterless” formulation of this type is described in EP-A-615720 in which a d-limonene based formulation is used for cleansing the skin. However, such a formulation has a particularly high citrus fragrance, leaving the hands with an undesirable and long-lasting residual orange citrus odour following use. Furthermore, solvents such as d-limonene and the like, may remove some of the skin's natural fats and such a formulation may have only a limited tendency to re-fat or moisturise the skin after cleansing. Since d-limonene is extracted from orange peel, it is also relatively costly. Moreover, its availability is dependent upon crop yields and its price is thus subject to fluctuation.
As an alternative to d-limonene based formulations, a blend of paramenthadienes has recently been proposed for use as a cleansing agent (see WO-A-97/09033). However, as with d-limonene, there is frequent variation in the ingredient quality of such “natural” solvents due to crop variations. This can present difficulties in formulating a product of consistent quality.
There has also been growing concern recently over damage to the atmosphere due to the emission of volatile organic compounds from a wide variety of commercial products including industrial cleansing products, such as those containing the solvent d-limonene or isomers of d-limonene, e.g. paramenthadienes.
The use of particularly high concentrations of non-volatile vegetable oils and fatty acid esters has been proposed as a replacement for traditional volatile solvents for various cleaning purposes, particularly in the removal of printing ink and other oily contaminants from printing presses (see e.g. U.S. Pat. Nos. 5,104,567, 5,194,173, 5,380,453, 5,143,639 and SUBSPRINT Project—promoting the use of vegetable oil cleaning agents in the printing industry). EP-A-615720 also suggests that vegetable oils may be useful in solubilising greasy, oily soils from the skin.
Various oils, including vegetable oils and fatty acid esters, optionally in combination with other emollient oils such as mineral and/or silicone oils, have also been proposed for use in formulations for cleansing the face, e.g. to remove make-up compositions comprising natural and/or synthetic waxes (see e.g. U.S. Pat. Nos. 4,806,572 and 5,585,104).
However, we have now surprisingly found that oil-in-water emulsions comprising one or more fatty acid esters are effective as a “waterless” cleanser in the. removal of heavy duty contaminants, in particular ingrained soils, from the surface of the skin whilst at the same time potentially serving to effectively moisturise the skin. The present invention thus provides a hand cleanser formulation having a strong cleansing action, but which is also of mild and soothing benefit to the hands and, in particular, is non-irritating.
According to one aspect, the present invention thus provides an aqueous hand cleanser formulation comprising:
(a) up to 25% by weight of a fatty acid ester or mixture of such esters;
(b) at least one emulsifying surfactant; and
(c) from 75 to 99% by weight of water.
Aqueous cleansing formulations in accordance with the invention have been found to be particularly effective in the removal of a variety of soils from the surface of the skin, in particular ingrained oily, greasy soils, and are thus envisaged to be of particular use to those working in industry.
The formulations in accordance with the invention can be used to cleanse the skin in the absence of any additional water during the cleansing process. The invention thus provides an alternative “waterless” hand cleanser which is not only effective in solubilising soils, but also which is believed to be effective in moisturising the skin without leaving any long-lasting residual odour on the skin surface.
Furthermore, the use of a fatty acid ester, or mixture of fatty acid esters, as the cleansing agent overcomes the problem of emission of volatile organic compounds associated with the use of conventional industrial cleansing agents. Thus, there are no vapour or unacceptable odour problems associated with the use of such agents in a hand cleansing formulation. Moreover, the cleansing formulations in accordance with the invention are biologically decomposable and thus present no disposal problems. They are also non-toxic.
Conveniently, the nature and amount of the surfactant present in the cleansing formulation is such that this is effective to stabilise the oil-in-water emulsion, i.e. this is capable-of emulsifying the fatty acid ester components and any other components present in the formulation which require emulsification. As a result, the cleansing formulation in accordance with the invention is preferably a substantially homogeneous emulsion.
Whilst not wishing to be bound by theoretical considerations, it is believed that maintaining the fatty acid ester in an oil-in-water emulsion enhances its cleansing potential since the emulsion has a larger volume than a “non-emulsified” mixture thereby allowing a greater solubilisation of oily, greasy deposits.
The fatty acid ester, or mixture of fatty acid esters, is an essential component of the cleansing formulation and may preferably constitute the principal cleansing agent present in the formulation. Preferably, the formulation in accordance with the invention is substantially free from any additional mineral or vegetable oil.
The formulation of the invention may contain further cleansing agents such as d-limonene and paramenthadienes e.g. in an amount of up to 10% by weight. However preferably, the formulations according to the invention are substantially free from any volatile organic solvents, such as paraffin hydrocarbons, alcohols etc. Particularly preferably, the formulation is substantially non-volatile.
As used herein, the term “fatty acid ester” is intended to cover any mono-, di- or tri-ester in which one or more ester moieties are derived from a fatty acid.
The aqueous cleansing emulsion suitable for use in the abrasive article according to the invention can contain a wide range of fatty acid esters.
In general, the fatty acid used to form the esters will have from 1 to 22 carbon atoms, preferably from 8 to 22, more preferably from 8 to 18, most preferably from 8 to 12. Particularly preferred fatty acids are those having an even number of carbon atoms. The fatty acids may be straight-

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