Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-03-31
2001-12-18
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S031000, C424S401000, C524S731000, C524S268000
Reexamination Certificate
active
06331604
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to silicone compositions, more particularly to a fatty alcohol- or aliphatic diol-grafted rubber-like silicone gel compositions and to a process for preparing them. The resulting compositions can be used as gelling agents for oils, including hydrocarbon oils, vegetable oils, and silicone oils. The process provides a simple and efficient method to prepare such compounds exhibiting high yield, high purity, and low cost.
BACKGROUND OF THE INVENTION
Oil gels are often desirable application vehicles for personal care products and cosmetic make-ups because they can provide a thin, water resistant, substantive film on skin. They are usually stable over time and convenient to apply. Some oily compounds exist in paste form at room temperature, such as Vaseline and lanolin, and may be directly utilized as an application vehicle. Others exist in liquid form, such as jojoba oil and bois oil, and may need to be converted to a gel form for use in a formulation. Various organic waxes, organic resins, and polymers have been employed as potential gelling agents for an oil medium. The resulting oil gels are generally very oily and particularly sticky if a polymer is utilized as the gelling agent.
Silicone polymers, particularly volatile silicones and low molecular weight silicones having a viscosity of below 50 cPs, have been used in an attempt to reduce the sticky feel and improve the extendibility but, they cannot reduce the oily feel and appearance on skin. Such an oily cosmetic composition is disclosed in U.S. Pat. No. 5,266.321, issued to Shukuzaki et al. Shukuzaki et al., disclose an oily make-up composition comprising an oil base, a silicone gel composition, and a cosmetic powder material. The silicone gel composition renders the make-up formulation less sticky and less oily, and provides a fresh, smooth feeling to the skin. The silicone gel composition disclosed therein consists essentially of a partially cross-linked organo polysiloxane and a low viscosity silicone oil. The silicone gel composition disclosed by Shakuzaki et al., however, is not quite compatible with most cosmetic oils. Its viscosity breaks down very sharply with an increased amount of a cosmetic oil, and thus it cannot be used as an efficient gelling agent. It may result in oil bleeding or phase split if incorporated in a cosmetic formulation.
In contrast to the art, the rubber-like silicone gel in the present invention comprises a fatty alcohol or aliphatic diol-grafted silicone network, as opposed to a pure silicone network, The compositions of the present invention demonstrate a sufficient compatibility with respect to the targeted cosmetic oils by maximizing the content of the fatty alcohol radical or aliphatic diol radical while preserving the desirable silicone characteristic.
The use of a silicone oil or a cosmetic oil or a mixture thereof, as opposed to a low viscosity silicone oil, also contributes to the beneficial characteristics of the compositions of the present invention.
The use of H
2
PtCl
6
.6H
2
O, as opposed to organic metal salts such as tin octoate as a catalyst taught in the art, for the reaction between a fatty alcohol or C
5
-C
22
aliphatic glycol and a methylhydrosiloxane polymer makes the process simpler and more efficient in terms of the yield, purity and cost.
SUMMARY OF TIE INVENTION
The present invention relates to a fatty alcohol- or a aliphatic diol-grafted rubber-like silicone gel which comprises a cross-linked fatty alcohol or aliphatic diol-grafted silicone network and a silicone fluid or a cosmetic oil or a mixture thereo, having a good compatibility with cosmetic oils and silicone oils and can be used as a gelling agent for these oils. The oil gels made by using the rubber-like silicone gel as a gelling agent provide a smooth, non-tacky, non-oily feel and can be utilized as an ideal cosmetic application vehicle.
The invention further relates to a method for preparing the said rubber-like silicone gel. This method involves a two step process: (1) reacting a fatty alcohol or aliphatic diol with a methylhydrodimethylsiloxane copolymer in the presence of an H
2
PtCl
6
.6H
2
O catalyst in a reaction medium of silicone oil or cosmetic oil or a mixture thereof and (2) further reacting the intermediate product mixture with vinyl silicone.
As the fatty alcohol radicals or aliphatic diol radicals are of high compatibility with most cosmetic oils, the cross-linked silicone network with these radicals chemically bonding on it has an increasingly higher compatibility with cosmetic oils than it would otherwise, and thus is capable of absorbing a considerable amount of those oils. The higher the level of the grafted radicals in the cross-linked silicone, the better the compatibility of the rubber-like silicone gel with those oils. The favored silicone characteristic will fade with increasing levels of radicals, therefore; the ratio of fatty alcohol radicals or aliphatic diol radicals to the silicone backbone should be balanced out according to the formulation requirement. A satisfactory result can be achieved when the level of fatty alcohol radicals or aliphatic diol radicals is about 3%-35%,.preferably 10-20%, by weight relative to the silicone backbone. The level of fatty alcohol or aliphatic diol radicals in the cross-linked silicone network can be easily varied in accordance with the synthesis of the present invention. This process provides a simple and efficient method for preparing a fatty alcohol- or aliphatic diol-grafted rubber-like silicone gel in terms of yield, purity and cost.
The level of radicals grafted on the crosslinked silicone can be controlled in the first step reaction of the present invention by changing the ratio of the fatty alcohol or aliphatic diol to the reactive silicone on the copolymer. The ratio is about 1:9 to 2:8 for an optimum balance between the oil compatibility and silicone characteristics. The oil compatibility also depends strongly upon the type of fatty alcohols or aliphatic diols used.
The process of the present invention is not limited to making silicone gel. This process may be easily modified to prepare fatty alcohol- or aliphatic diol-grafted silicone oils within the principle scope of the present invention.
The rubber-like silicone gel can then be mixed with a cosmetic oil, a silicone oil, or a mixture thereof. After the silicone gel swells up with the oil, the resulting product is ground to fine particles forming an oil gel useful in cosmetic and personal care products.
DETAILED DESCRIPTION OF THE INVENTION
A fatty alcohol- or aliphatic diol-grafted rubber-like silicone gel of this invention comprises a fatty alcohol- or aliphatic diol-grafted silicone network polymer; and, a silicone oil or a cosmetic oil or a mixture thereof This rubber-like silicone gel can be used as a gelling agent which will absorb up to about 400% of silicone oils or cosmetic oils relative to its own weight. The fully swelled granules of the said rubber-like silicone gel can be ground to a very smooth viscous gel form using, for example, a mixer of high shear rates or a three-roll mill. The resulting oil gel is an ideal cosmetic application vehicle that provides a fresh, smooth, non-tacky, non-oily feel on the skin.
The structure of the rubber-like silicone gel is characterized by a three-dimensional network of the repeat unit of Si—O backbone and two covalent organic radicals on each Si atom. The organic radicals include hydrogen atom, C
1
-C
3
alkyl group, phenyl group or the like, reacted fatty alcohol radical, i.e., alkoxy group, and reacted C
5
-C
22
diol radical, i.e., alkoxylol group. A typical chemical formula for the silicone network can be mainly described as containing a mixture of the following units:
(Me )
3
SiO
0.5
, Me(R
1
)SiO, (Me)
2
SiO, Me(R
2
)SiO, (Me)
2
(CH
2
═CH)SiO
0.5
, (Me)(C
2
H
4
)
0.5
SiO, and (Me)
2
(C
2
H
4
)
0.5
SiO
0.5
,
wherein R
1
is a hydrogen atom or vinyl group and R
2
is a C
5
-C
22
alkoxy group or a C
5
-C
22
alkoxylol group.
The ratio of the unit Me(R
2
)SiO to the rest
Hrubec Thomas J.
Wang James
Grant Industries, Inc.
Moore Margaret G.
Nissim Stuart H.
Woodbridge Richard C.
Woodbridge & Associates P.C.
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