Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-02-15
2002-05-14
Boyer, Charles (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S119000, C510S125000, C510S127000, C510S130000, C510S136000, C510S137000, C510S156000, C510S159000, C510S371000, C510S407000, C510S414000, C510S426000, C510S432000
Reexamination Certificate
active
06387857
ABSTRACT:
This invention relates to liquid cleansing compositions, in particular liquid cleansing products which are high foaming and have a high degree of mildness.
In recent years, it has increasingly become a desirable attribute of commercially available cleansing products, in particular those products for personal washing, that such products combine a rapid and abundant lather with improved mildness, in order to minimise skin damage.
It is well known that anionic surfactants confer lathering properties to compositions in which they are contained. A previously used approach to improving the mildness of compositions containing anionic surfactants has been to partially replace the anionic surfactants with a suitable coactive surfactant, which is typically an amphoteric and/or a nonionic surfactant. Without being bound by theory, it is thought that this partial replacement of the anionic surfactant in the composition serves to reduce the critical micellar concentration of the anionic surfactant composition, and thereby reduce its harshness.
A further approach to ameliorating the harshness of anionic surfactant containing compositions has been to include in the composition one or more hydrophobic and emollient materials, such as for example silicone oils, mineral oils or cholesterol. The addition of such hydrophobic materials has generally proved successful in enhancing the mildness of the cleansing composition, but with a tendency to consequently reduce the amount of lather that they produce in use, because of their hydrophobic nature.
In addition, a farther problem encountered is that cleansing compositions general have a tendency to be susceptible to bacterial and microbial gradation; this is unacceptable for any product which is to be applied to e skin for the purposes of washing or cleansing. Hence, with such products, usually a necessary component of the composition is a suitable organic anti-bacterial and/or anti-microbial agent. Typical examples of anti-microbial and/or anti-bacterial agents which are commercially available include those under the trade names Kathon CG (ex Rohm & Hass), Phenoxyethanol (ex Nipa Laboratories), Parabens (ex Nipa laboratories), Germall 11 (ex ISP) and Glydant plus (ex Lonza), as well as materials such as formaldehyde.
However, a disadvantage of incorporating such organic anti-bacterial and/or anti-microbial compositions into a personal wash composition is that these materials can provoke adverse skin reactions. This is thought to be due to their mode of action, and therefore their levels in the commercial product must be minimised. In addition, a number of anti-bacterial and/or anti-microbial agents are suspected of toxicity.
It would therefore be highly advantageous to manufacture a personal wash composition which has good lathering properties and enhanced mildness, whilst at the same time is devoid of any recognised organic anti-bacterial and/or anti-microbial agents, but which nevertheless possessed anti-microbial and/or antibacterial properties.
We have surprisingly found that it is possible to provide liquid personal wash compositions which have high levels of lather generation and very good levels of mildness, but which are absent any recognised organic anti-microbial and/or anti-bacterial agents. Thus, according to a first aspect of the invention, there is provided a personal wash liquid composition which comprises 10 to 40% of one or more anionic surfactants, 30 to 50% of one or more humectants, and less than 55% water, characterised in that the water activity of the product is less than 0.9.
Conveniently, compositions according to the invention are free of any anti-microbial and/or anti-bacterial agents.
Compositions according to the invention preferably contain at least 10% water. Compositions are also ideally not encapsulated.
Compositions according to the invention comprise relatively high levels of humectants, which preferably are polyol humectants. Examples of suitable humectants include glycerol, sorbitol, polyethylene glycol, and mono- and oligomeric sugars. A particularly preferred humectant is glycerol. Although not wishing to be bound by theory, it is believed that compositions according to the invention can exist satisfactorily without the use of conventional anti-microbial and/or anti-bacterial agents, because of the relatively low maximum water activity of the compositions. In particular, an upper level of water activity of 0.9 has been found, at which level or below cosmetic compositions according to the invention are “self preserving”.
In the context of the invention, the “water activity” (a) of the composition is defined as a=p/p
o
, where p is the measured partial pressure of the solution and p
o
is the partial pressure of distilled deionised water. Unless stated otherwise, all water activities are quoted are at ambient temperature. Further references to water activity (or relative humidity, where relative humidity (RH)=100 a) can be found in Morris, C. and Leech, R., “Natural and Physical Preservative Systems”, Curry, J. “Water Activities and Preservatives”, Cosmet. Toilet. 100, 53-55, and Christian, J. H. B., “Reduced Water Activity”. In:Silliker, J. H. (ed) “Microbial ecology of Foods”, vol. 1, Academic Press, New York, pp170-192.
In addition to the relatively low water activity that the high levels of humectants provide in topical compositions, we have surprisingly found that relatively high levels of humectants do not negatively affect the lathering or sensorial properties of the topical compositions. They can however contribute positively to the mildness of the product.
Compositions according to the invention have a water activity of less than 0.9, preferably less than 0.87, more preferably less than 0.85, and even more preferably less than 0.81.
Cosmetic compositions according to the invention comprise a surfactant component which itself contains an anionic surfactant. The surfactant component contained in the composition may be any combination of surfactants, provided that it comprises an anionic surfactant, and that it provides the composition with a suitable level of foaming. As such, the surfactant component of the composition may comprise in addition to anionic surfactants soaps, cationic, nonionic, zwitterionic and amphoteric surfactants, and mixtures thereof.
Suitable soaps include these having carbon chain lengths of C
8
-C
24
, be saturated or unsaturated, and have any appropriate cation, such as sodium, potassium, ammonium or triethylammonium.
The composition according to the invention comprises an anionic surfactant, which may preferably be chosen from alkyl sulphates, alkyl ether sulphates, alkyl sulphonates, alkyl aryl sulphonates, olefin sulphonates, acyl sarcosinates, acyl taurides, acyl isethionates, nonoalkyl sulphosuccinates, dialkylsulphosuccinates, N-acylated &agr;-amino acids, alkyl carboxylates, monoalkyl phosphates and dialkyl phosphates, and mixtures thereof. Specific examples of suitable anionic surfactants include:
alkyl sulphates, such as sodium lauryl sulphate [eg EMPICOL CX available from Albright and Wilson], and triethanolaminde lauryl sulphate [eg EMPICOL TL40/T, available from Albright and Wilson];
alkylether sulphates, such as sodium lauryl ether sulphate [eg EMPICOL ESB70, available from Albright and Wilson];
alkyl sulphonates, such as sodium alkane (C
13-18
) sulphonate [eg HOSTAPUR SAS 30, available from Hoechst];
alkylaryl sulphonates, such as sodium alkyl benzene sulphonate [eg TEEPOL CM44, available from Shell];
olefin sulphonates, such as sodium olefin sulphonate (C
5-18
) [eg HOSTAPUR OS, available from Hoechst];
acyl sarcosinates, having the structure: (51)
where
R
3
is chosen from C
6-14
alkyl, and
M is a counterion chosen from alkali metals, ammonium and substituted ammonium such as alkanolammonium.
An example of an acyl sarcosinate having the structure (51), is sodium lauryl sarcosinate [eg HAMPSOYL L-95, available from Grace].
acyl taurides, having the structure (52):
wherein R
4
is
Chambers John George
Moore Phillip
Boyer Charles
Koatz Ronald A.
Unilever Home & Personal Care USA , division of Conopco, Inc.
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