Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form
Reexamination Certificate
2001-02-15
2003-09-16
Celsa, Bennett (Department: 1639)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Particulate form
C510S101000, C510S312000, C510S524000, C510S525000, C510S526000, C514S937000
Reexamination Certificate
active
06620437
ABSTRACT:
FIELD OF INVENTION
This invention relates to a composition and method for “post-adding” cosmetic attributes to a fabric softening base composition at the final stage of its manufacture. More particularly it relates to a water-in-oil microemulsion which is suitable for containing adjuvants such as perfume or colorant and which can be readily mixed with a fabric softening base composition with only a minimum amount of shear and without adversely affecting its physical stability.
BACKGROUND OF THE INVENTION
Perfumes and colorants are routinely introduced into liquid fabric softening compositions to provide appealing cosmetic attributes for the consumer. The introduction of perfume, for example, to a liquid softening composition, is meant to leave a pleasant and lasting fragrance on the treated fabrics. The colorant is intended to provide a visually pleasing product as well as convey to the consumer an overall impression of softness and quality. From a marketing standpoint, perfumes and colorants are attributes which allow the formulator a degree of flexibility to provide product variety for a given softening technology or for a fixed fabric softening base composition.
Although perfume, on a weight basis, is invariably a very minor component of a commercial fabric softener composition, its introduction into the composition in an efficient manner is a subject of much concern in the formulation art. This is particularly true for concentrated fabric softeners containing more than about 10% by weight of active softening ingredients insofar as the aqueous softener base compositions tend to gel in the presence of water-immiscible perfume. This tendency of gel formation is particularly problematic when the water-immiscible perfume is poorly dispersed in the aqueous emulsion which constitutes the softening base composition.
Undesirable thickening or gelation of a softener base composition has significant drawbacks: it reduces the effective shelf life of the final product and adversely affects consumer acceptance for a softener product which upon use has thickened to an unexpectedly viscous mass instead of meeting the consumers expectation of being essentially free-flowing. As a result the prior art has addressed itself to overcoming the pervasive problems of gelation and the formation of high viscosity liquids which accompany the introduction of water-insoluble perfumes into aqueous fabric softener base compositions.
U.S. Pat. No. 5,447,644 to International Flavors & Fragrances (IFF) describes a method to avoid gelation of the softening composition resulting from the introduction of increased levels of perfume into a softener base composition. According to this method there is first formed an aqueous microemulsion by mixing the perfume with a defined nonionic surfactant under conditions of high shear to uniformly disperse the perfume in the surfactant/water mixture. The perfume-containing microemulsion is then mixed with a fabric softener base formulation to form the final fabric softener composition. A high shear mixer is required for this mixing operation.
Accordingly, there remains a need in the art for a method to readily introduce fragrances and colorants into a fabric softener base at the very end of the manufacturing process or even by the consumer himself in the home under very gentle mixing conditions, avoiding the need for high shear mechanical agitation and equipment. Further, there is a need for a method which apart from incorporating perfume or colorants into a base formulation, will do so without adversely impacting the rheological and physical stability of the final product.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a perfume-containing water-in-oil microemulsion capable of being mixed with a perfume-free fabric softener base composition which is in the form of an aqueous emulsion so as to disperse perfume in said aqueous emulsion under conditions of low shear while avoiding any problem of gelation to thereby provide a physically stable perfume-containing liquid fabric softening composition, said water-in-oil microemulsion comprising:
(a) from about 5% to about 80%, by weight, of a surfactant fabric softener selected from the group consisting of:
(i) diester quaternary ammonium compounds having the structural formulae as follows:
wherein each
A is independently C(O)O—R′ or —O(O)C—R′;
R is a lower alkyl group having 1 to about 4 carbon atoms;
R′ is an alkyl or alkenyl group having 8 to about 22 carbon atoms;
R″ is independently a lower alkyl radical having 1 to about 6 carbon atoms or hydroxyl alkyl group or H;
n is an integer having a value of 1 to about 3; and
X
−
is a softener compatible anion; and
wherein B is independently A or (R)
n−
A; and A, R, R″ and n are as defined above; and
wherein A, R, R″ and n are as defined above; and/or
(ii) diamido ammonium compounds having the formula:
wherein n, X
−
and R′ are as defined above, R
1
is a lower alkyl radical having 1 to about 4 carbon atoms or hydrogen, and R is an alkylene radical having 2 to about 4 carbon atoms;
(b) from about 2% to about 50%, by weight, of an organic solvent;
(c) from about 15% to about 70%, by weight, of a water-immiscible perfume, components (a), (b) and (c) comprising the oily phase of said microemulsion;
(d) from 0% to about 1% of a colorant; and
(e) from about 0.5% to about 26%, by weight, of water; said microemulsion being free of an anionic surfactant, and having a weight ratio of said oily phase to water of from about 3:1 to about 200:1 with the proviso that for weight ratios of said oily phase to water of below 9:1, the weight ratio of perfume to solvent is less than 1:1; and/or the surfactant fabric softener (a) is greater than 25%, by weight, and wherein the percentages of components (a), (b) and (c) are selected so that the resulting composition forms a water-in-oil microemulsion.
Danielsson and Lindman, “The definition of Microemulsion”, Colloids and Surfaces, 3 (1981), 391-392, Elsevier Scientific Publishing Company, have defined a “microemulsion” as ‘a system of water, oil and amphiphile which is a single optically isotropic and thermodynamically stable liquid solution’. This definition of microemulsion is used herein in describing the present invention.
In accordance with the above definition, a microemulsion has the following characteristics/properties:
i) Clear
ii) It is free of lyotropic liquid crystalline system (i.e. it is isotropic)
iii) It has relatively low viscosity
iv) It is formed spontaneously by simple mixture/agitation of all components (i.e. it is thermodynamically stable)
More detailed information concerning various aspects of microemulsion systems such as definition, phase behavior, structure, low interfacial tensions and dynamics, is disclosed in R. Zana's article, ‘Microemulsions’ in Heterogeneous Chemistry Reviews, Vol. 1, 145-157 (1994), edited by John Wiley & Sons Ltd, the disclosure of which is incorporated herein by reference.
The present invention also provides a method for introducing a perfume into a perfume-free fabric softener base composition which is in the form of an aqueous emulsion under conditions of low shear and without adversely affecting its physical stability comprising the steps of:
(a) providing a perfume-containing water-in-oil microemulsion as defined above; and
(b) mixing an amount of said water-in-oil microemulsion sufficient to contain the desired amount of perfume with said fabric softener base composition under conditions of low shear thereby causing the inversion of said microemulsion and the dispersion of the perfume to form a physically stable perfume-containing liquid fabric softening composition.
The water-in-oil microemulsion compositions of the invention are predominantly comprised of the oily phase as defined above, namely, the cationic surfactant fabric softener, the organic solvent and the water-insoluble perfume. To form a composition in the desired phase of a water in oil microemulsion, the amount of water s
Ewbank Eric
Tummers Dominique
Celsa Bennett
Colgate-Palmolive Co.
Lieberman Bernard
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