Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-09-13
2002-04-16
Metzmaier, Daniel S. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S261000, C524S588000, C516S023000, C424S065000, C424S401000, C514S938000
Reexamination Certificate
active
06372830
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a water-in-oil type silicone emulsion composition, more particularly to a water-in-oil type silicone emulsion composition having excellent stability to temperature changes, high safety against the skin and excellent texture when applied to the skin.
DESCRIPTION OF THE RELATED ART
Silicone fluids and gumlike siloxane high polymers, so-called silicone gums, are characterized in that they are physiologically highly safe, hardly deteriorate and have excellent water repellency, and cosmetics containing such high polymers, when applied to the skin or the like, spread well, are less tacky and impart oil-free and smooth touch and gloss to the skin, so that they are widely employed cosmetic ingredients. Meanwhile, cyclic dimethylsiloxane oligomers are employed as ingredients for antiperspirants and the like because of their excellent compatibility with silicone fluids and hydrocarbon cosmetic ingredients, excellent spreadability and absence of chilliness when they volatilize.
There are disclosed a number of techniques for obtaining stable oil-in-water type emulsions of polyorganosiloxanes by means of emulsion polymerization using ordinary surfactants as emulsifiers or in the presence of specific emulsifiers. However, water-in-oil type emulsion compositions of polyorganosiloxanes are not yet successful in exhibiting satisfactory stability to temperature changes.
As a method for obtaining water-in-oil type emulsion compositions of polyorganosiloxanes, there is known a technique of employing various kinds of lipophilic polyorganosiloxane-polyoxyalkylene block copolymers as emulsifiers. It should be noted here that the block copolymers referred to herein mean those each having a linear polyorganosiloxane as the main chain and polyoxyalkylene chains at the terminal ends and/or as side chains and include so-called graft copolymers having polyoxyalkylene chains as side chains only.
For example, Japanese Provisional Patent Publication Nos. 66752/1986, 212321/1986, 212324/1986, 218509/1986, 45656/1987 and 54759/1987 disclose water-in-oil type emulsion compositions of polyorganosiloxanes prepared by using block copolymers of various structures as emulsifiers and by adding organically modified clay minerals. In Examples of these official gazettes, there are employed as such polyorganosiloxanes containing polyoxyalkylene chains at each terminal end and as side chains those having relativity low viscosity values of 60 to 200 cSt at 25° C. While it is reported that these compositions are stable at temperatures of 0 to 50° C. and are also stable to a temperature cycle between 5 and 45° C., they failed to show sufficient stability to temperature cycles including cooling to a low temperature of −10° C.
Japanese Provisional Patent Publication No. 215510/1987 discloses water-in-oil type emulsion compositions of polyorganosiloxanes prepared by using like polyorganosiloxane-polyoxyalkylene block copolymers as emulsifiers and containing in the aqueous phases organic salts respectively. Meanwhile, it is disclosed in Japanese Provisional Patent Publication Nos. 216635/1987, 119844/1988, 180237/1989 and 88513/1989 to prepare like water-in-oil type emulsion compositions using like polyorganosiloxane-polyoxyalkylene block copolymers in combination with other surfactants, gelling agents, etc. Of the block copolymers employed in Examples of these official gazettes, those having polyoxyalkylene chains at each terminal end and as side chains all have polyorganosiloxane chains with polymerization degrees in the range of 64 to 162. However, none of these emulsion compositions have sufficient stability to temperature cycles.
Meanwhile, it is disclosed in Japanese Provisional Patent Publication Nos. 203466/1989 and 93136/1993 to effect emulsification of polyorganosiloxanes using as emulsifiers block copolymers each having a polyoxyalkylene chain at one terminal end of the polyorganosiloxane chain having 50 or less or 150 or less silicon atoms to provide water-in-oil type emulsion compositions having excellent stability to dilution. However, those emulsions obtained using such emulsifiers still do not have sufficient stability to temperature cycles.
Further, it is disclosed in Japanese Provisional Patent Publication Nos. 24959/1979, 268831/1996, and 268832/1996 to use polyorganosiloxane-polyoxyalkylene block copolymers including those of high-molecular weight region as emulsifiers to prepare water-in-oil type emulsion compositions of polyorganosiloxanes. Of the block copolymers employed in examples of these official gazettes, those of the type having polyoxyalkylene chains at each terminal end and as side chains have high polyorganosiloxane chain polymerization degrees of 1.011, and none of emulsion compositions of these block copolymers are successful in satisfying both stability as emulsions per se and stability to temperature cycles.
As a result of out studies, such block copolymers having polyorganosiloxane chains of low polymerization degrees generally provide emulsion compositions having poor stability to temperature cycles, whereas those having polyorganosiloxane chains of high polymerization degrees exhibit poor effects as emulsifiers, and the resulting emulsion compositions per se come to have poor stability.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide water-in-oil type emulsion compositions of polyorganosiloxanes which are stable as emulsions per se and show excellent stability to temperature changes particularly to those including cooling to low-temperature regions of −5° C. or lower and which cause no oil phase and/or aqueous phase separation. Another objective of the present invention is to provide a water-in-oil type emulsion composition which has excellent stability to the temperature changes as described above and is incorporated with components necessary for cosmetics and the like such as salts.
We made studies with a view to attaining the above objectives to find that the intended objectives can be attained by using as an emulsifier a block copolymer having a molecular structure within a specific range where polyoxyalkylene chains are present at each terminal end and as side chains of a polyorganosiloxane chain having a polymerization degree within a specific range and accomplished the present invention.
To describe more specifically, the water-in-oil type emulsion composition according to the present invention is characterized in that it contains:
(A) at least one sort of polyorganosiloxane;
(B) at least one sort of polyorganosiloxane-polyoxyalkylene block copolymer represented by the general formula (I):
wherein R
1
s each represent a methyl group and some of R
1
s may be phenyl groups; Es each represent a group of the general formula (II):
wherein R
2
represents a hydrogen atom, an acyl group or an alkyl group having 1 to 4 carbon atoms; p is an integer of 3 to 6; a is an integer of 2 to 50; b is an integer of 0 to 50; and a+b is an integer of 5 to 100; m is an integer of 300 to 600; n is an integer of 1 to 30; and m+n is an integer of 300 to 600; and
(C) water.
MODE FOR CARRYING OUT THE INVENTION
The component (A) employed in the emulsion composition of the present invention is a polyorgano-siloxane constituting the oil phase as a continuous phase and includes silicone fluids ranging from those of low-viscosity values to high-viscosity values and gumlike siloxane high polymers which may be linear or contain small amounts of branched siloxane structures. The component (A) also includes linear or cyclic siloxane oligomers, trimethylsiloxysilicic acid and cyclic compounds thereof. The organic groups bonded to the silicon atoms include linear or branched alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, dodecyl, tetradecyl, hexadecyl and octadecyl; cycloalkyl groups such as cyclohexyl; aralkyl groups such as 2-phenylethyl and 2-phenylpropyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl and tolyl; and substituted monovalent hydrocarbon
Kilgour John A.
Sato Yoshiyuki
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