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
2003-05-28
2004-12-21
Peng, Kuo-Liang (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...
C526S319000, C526S303100, C424S070160
Reexamination Certificate
active
06833406
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to liquid dispersion polymer compositions which comprise a dispersed polymer phase, a continuous carrier phase and a surfactant, their preparation and the use of these liquid dispersion polymer compositions to prepare microparticulate thickening systems which thicken aqueous or aqueous/organic compositions. More particularly it relates to liquid dispersion polymer compositions which comprise microparticles of a hydrophilic, water soluble or swellable polymer, preferably an acrylic-based polymer, which is dispersed in a silicone polymer fluid carrier phase and an oil-in-water surfactant, their preparation and the use of these liquid dispersion polymer compositions to prepare microparticulate thickening systems to thicken aqueous or aqueous/organic compositions, particularly for use in personal care and pharmaceutical formulations.
Thickeners are used extensively in personal care formulations such as cosmetic and pharmaceutical formulations, to affect the aesthetics, product application and suspension and delivery of the active raw materials. Polymeric thickeners have been used for this purpose for many years. The types of polymeric thickeners that have been used range from natural gums such as guar, through modified natural materials such as hydroxyethyl cellulose, to synthetic thickeners such as the Carbomers® based on polyacrylic acids.
The Salcare® range of liquid dispersion polymers, available through Ciba Specialty Chemicals, is a range of microparticulate acrylic-based polymeric thickeners in a hydrophobic carrier medium. Salcare® SC91 is an anionic thickening agent based on a sodium acrylate polymer and mineral oil carrier with PPG-1 trideceth-6 as the activator surfactant. Salcare® SC92 is a cationic copolymer thickener and conditioner comprising polyquaternium 32 and mineral oil. Salcare® SC95 and Salcare® SC96 are cationic homopolymer thickeners and conditioners. Salcare® SC95 comprises polyquaternium 37 in mineral oil with PPG-1 trideceth-6. Salcare® SC96 comprises polyquaternium 37 in propylene glycol dicaprylate dicaprate with PPG-1 trideceth-6. Salcare AST is an anionic thickening agent based on a sodium acrylate polymer in soya bean oil with PPG-1 trideceth-6.
The tiny, spherical microparticles of the above hydrophilic acrylic polymers, whether anionic or cationic in charge, have a typical particle size in the range of 0.1-2 microns, with an average particle size in the range of 0.5-1.0 microns. The polymer microparticles are preferably manufactured by methods in which water soluble vinyl addition monomers are polymerized utilizing a water-in-oil polymerization route.
On stirring of any of the above liquid dispersion polymers into an aqueous system, the activator surfactant converts the hydrophobic carrier into an oil-in-water emulsion. By the term “activator surfactant” is meant a surfactant which activates the conversion of the hydrophobic carrier into an oil-in-water emulsion. At the same time the hydrophilic polymer expands on exposure to water but does not dissolve, resulting in a smooth and rapid viscosity increase. Typically the polymer particles swell to give a microparticulate thickening system comprising polymer particles having a typical particle size in the range of 2.5-5 microns in diameter. Since the water molecules move into the small polymer particles by osmosis, the osmotic effect experienced by the polymer particle is a balance between water and any electrolyte present in the system. Hence high electrolyte levels reduce the swelling of the polymer particles.
The microparticulate thickening systems have a pseudoplastic rheological profile which gives good stability and suspension characteristics at low shear rates (such as those experienced by the product on standing), and low apparent viscosity's at high shear rates, which corresponds to excellent rub-in characteristics.
As previously mentioned, the continuous organic carrier phase for the above Salcare® liquid dispersion polymers is provided at least in part by a silicone polymer fluid.
SUMMARY OF THE INVENTION
In one aspect the present invention provides a liquid dispersion polymer composition comprising a hydrophilic, water soluble or swellable polymer as a dispersed polymer phase, a silicone polymer fluid as a continuous carrier phase and an oil-in-water surfactant, wherein the polymer is in the form of microparticles having an average particle size in the range of 0.1 to 2 microns.
Typically the liquid dispersion polymer composition comprises
a) from 35% to 65% by weight of the polymer,
b) from 20% to 50% by weight of a silicone polymer fluid, and
c) from 5% to 25% by weight of a surfactant or a surfactant mixture, each based on the total weight of the composition.
Advantageously the hydrophilic polymer a) is water swellable, i.e. it is sufficiently cross-linked to swell but not dissolve in water. Preferably it is acrylic-based. Also it is preferably anionic or cationic.
The silicone polymer fluids b) are well known to the cosmetic industry and have been used for many years in hair and skin formulations. They are particularly favored over mineral oils for their improved aesthetic feel on skin and hair and also for the sheen they impart when employed in hair care applications. The products of the instant invention provide a compatibility across the different ionic systems and give a level of formulation versatility using silicone technology that is not provided by any other liquid dispersion polymer.
Preferably the surfactant mixture c) comprises both surfactants useful in the manufacture of the microparticles of swellable polymer a), and at least one surfactant which serves as the activator for the subsequent oil-in-water microparticulate thickening emulsions. This activator surfactant for the oil-in-water thickening emulsions comprises from 1.0% to 10.0% by weight of the composition, preferably from 2.0% to 8.0% by weight of the composition. Preferably the activator surfactant is a nonionic oil-in-water emulsifier having a HLB generally above 7. Suitable emulsifiers of this type are well known to those skilled in the art. Ethoxylated alcohols are preferred.
Additionally the composition may contain minor amounts of other components which do not affect its essential characteristics. Typically these other components may include up to about 3% by weight each of water and volatile organic solvents as well as small amounts of other components which are left over from the preparation of the water soluble or swellable polymers.
Advantageously the composition comprises
a) from 40% to 60% by weight of the polymer, wherein the polymer is anionic or cationic and is water swellable,
b) from 25% to 45% by weight of a silicone polymer fluid, and
c) from 8% to 20% by weight of a surfactant or a surfactant mixture, each based on the total weight of the composition.
A particularly preferred composition comprises
a) from 45% to 58% by weight of the polymer, wherein the polymer is anionic or cationic and is water swellable,
b) from 30% to 40% by weight of a silicone polymer fluid, and
c) from 10% to 18% by weight of a mixture of surfactants, each based on the total weight of the composition.
A very particularly preferred composition comprises
a) from 45% to 58% by weight of the water swellable polymer, wherein the polymer is cationic,
b) from 32% to 38% by weight of a silicone polymer fluid,
c) from 12% to 18% by weight of a mixture of surfactants, each based on the total weight of the composition.
Still another aspect of the present invention is the provision of thickened aqueous or water-containing compositions, in particular personal care formulations, which comprise
a) 0.1% to 8% by weight, preferably 1% to 6% by weight of a liquid dispersion polymer composition as described above,
b) 0.1% to 70%, preferably 2% to 35% by weight of additional ingredients, for example personal care ingredients such as cosmetic or pharmaceutical excipients and/or active ingredients and
c) 45% to 99% of water or a mixture of water and a water-miscible organic solvent
Dungworth Howard Roger
Gavin Dwayne Erick
Green Michael
Ridley Eleanor Bernice
Ciba Specialty Chemicals Corporation
Mansfield Kevin T.
Peng Kuo-Liang
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