Organic compounds -- part of the class 532-570 series – Organic compounds – Fatty compounds having an acid moiety which contains the...
Reexamination Certificate
2002-02-15
2003-07-22
Carr, Deborah D. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Fatty compounds having an acid moiety which contains the...
C554S169000, C554S227000, C424S401000
Reexamination Certificate
active
06596886
ABSTRACT:
The invention relates to the field of fine chemicals. More precisely, the invention relates to a process for the manufacture of a non-oily emollient.
Emollients are widely used in the cosmetic and pharmaceutical industries to render dry skin soft and to improve its elasticity. The term emollient generally refers to the set of perceptions conveyed by the senses of touch and sight. Perceptions evoked by touch are softness, elasticity and smoothness. Perceptions evoked by sight are shininess and dullness.
A considerable number of emollients are offered by suppliers of cosmetic starting materials. These emollients differ from each other in terms of their chemistry, as well as in terms of the result of two factors: emollience on application and residual emollience. There are therefore emollients with a protective effect, others with a highly oily effect, while some give the impression of dryness and others still have an astringent effect.
The vast majority of emollients are characterised by the presence of fatty acids with fairly long carbon chains, either linear or branched. These fatty acids are themselves combined, in the form of esters, with alcohols with more or less long carbon chains which are also linear or branched. It is these esters and fatty acids which constitute the basis of the emollient effect. Generally, two groups of esters are considered to make up this category of emollient: those of a completely natural origin and those of synthetic origin, synthesis meaning esterification of the fatty acid by an alcohol. Synthetic esters are usually manufactured from saturated fatty acids. This confers great stability on them with regard to oxidation but eliminates the possibility of their being involved in any biosynthetic processes in the epidermis. It is well-established that polyunsaturated fatty acids (linoleic and linolenic acid), called essential fatty acids, can be transformed by the enzymes of the epidermis into other polyunsaturated fatty acids which, amongst other effects, are likely to limit the loss of transepidermal moisture. This limiting effect on loss of moisture provides skin emollience and it is this emollient effect that is sought after in esters of natural origin, such as those found in plant oils and fats, marine oils and some animal fatty materials.
All these fatty materials consist of a mixture of esters that are triglycerides or triesters of glycerol and fatty acids. It is the properties of the fatty acids found in these esters which give the resultant fatty material its consistency. Therefore the richer these fatty materials are in saturated fatty acids, the greater their consistency to the point where fairly solid fats or butters are obtained at 20° C. Totally solid products can actually be obtained at this temperature with completely hydrogenated fats. Conversely, the lower the content in unsaturated fatty acids (mono- or poly-), the more likely the fat is to be totally fluid at 20° C.
This is true of vegetable oils which are characterised by a composition in which overall content in unsaturated fatty acids is often greater than 85%. The liquid consistency of oils is one advantage in terms of an emollient effect. To this fluid consistency is added the effect of essential fatty acids such as linoleic acid, always present in vegetable oils in varying proportions as a function of the botanical origin of oleaginous species from which they originate. As mentioned earlier, transformation of linoleic acid into other unsaturated fatty acids via a biosynthetic process leads to a significant moisturizing effect which contributes to maintaining the epidermis in a good state of emollience. Finally, the important biological role played by the unsaponifiable compounds present, such as squalene, carotene, triterpenic alcohols and phytosterols, have to be taken into consideration with vegetable oils. These oils can, however, be completely hydrogenated to give emollient fatty materials, devoid of biological activity but oxidatively very stable, and which have the required consistency for some creams.
While all these advantages are well known, vegetable oils and fatty materials in general nonetheless have the serious disadvantage of being oily to the touch after application to the skin because of their low rate of skin penetration. Generally speaking, the rate of percutaneous penetration of a molecule is inversely proportional to its molecular weight. This rate is relatively high for a molecular weight of 400 Dalton but above this molecular weight, the rate of penetration decreases considerably. However, the molecular weight of triglycerides in vegetable oils is around 870 Dalton, much higher than the limit of 400 Dalton. It is therefore clear that vegetable oils, such as those used in cosmetic and pharmaceutical formulations, can give the impression of being oily as a result of triglycerides which only penetrate the skin very slowly.
The problem faced is therefore to find a process for manufacturing emollients where the molecular weight of the principal compounds is below about 600, preferably around 500, and still more preferably below about 450 Dalton, in order to obtain vegetable oil and fatty materials based emollient preparations that are not oily to the touch. The second objective consists in transforming vegetable oils or fatty materials in general and purifying the product obtained under conditions such that the intactness of their fatty acids and insaponifiable matter is not lost so that all the properties of fatty materials can be exploited without the inconvenience of their being oily.
This problem is resolved by the process of the invention which is comprised of the following steps:
a) interesterification of the triglycerides contained in a fatty material, preferably of vegetable origin, by a primary alcohol, preferably of plant origin, in the presence of a catalyst;
b) elimination of the catalyst;
c) distillation of the residual alcohol, preferably in the presence of a bleaching agent, followed by elimination of the bleaching agent;
d1) either frigelisation of the preferably bleached residue such that residual glycerides are at least partially crystallized, followed by elimination, especially by filtration, of said crystallized residual glycerides;
d2) or hydrogenation of the residue, preferably bleached.
In step d1), said residual glycerides are mono-, di- or triglycerides resulting from esterification by said primary alcohol in step a). Their elimination results in products that are completely liquid at the frigelisation temperature, notably at room temperature, preferably at a temperature of at least 15° C.
In step d2), hydrogenation of the residue leads to the formation of products with higher melting points at room temperature, generally melting points between a temperature of 25° C. and 80° C., depending on the molecular weight of the products.
In the sense of this invention, “fatty material” refers to a refined or crude vegetable oil or fat, possibly hydrogenated, a refined or crude marine oil, possibly hydrogenated, or a refined or crude animal fat, possibly hydrogenated, or a refined or crude anhydrous dairy fat, possibly hydrogenated.
The alcohol use in the interesterification step can be chosen from the C
1
-C
22
alcanols, C
3
-C
22
alcenols or C
3
-C
22
branched alcohols. These branched alcohols are alcohols likely to carry C
1
-C
8
alkyl substituents. Among the C
1
-C
22
alcanols, C
4
-C
18
alcanols are preferred, particularly C
6
-C
18
alcanols. Among the C
3
-C
22
branched alcohols, C
8
-C
22
alcohols are preferred. The fatty acid esters obtained from C
1
-C
22
branched primary alcohols, preferably C
6
to C
18
, are called wax-esters in this invention. The term wax-esters generally covers esters of fatty acids and fatty alcohols that are solid at room temperature. By extension, the term is also used to cover any fatty acid or fatty alcohol esters that are solid or liquid at room temperature obtained in accordance with this invention. By varying the length of the saturated alcohol used, it is possible to obtain wax-esters from
Carr Deborah D.
Dennison, Schultz & Dougherty
Sophim
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