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
1995-12-28
2003-03-04
Sellers, Robert E. L. (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...
C424S401000, C524S556000, C526S209000, C526S213000
Reexamination Certificate
active
06528575
ABSTRACT:
The present invention relates to the use of crosslinked copolymers which are prepared by precipitation polymerization of monomer mixtures comprising
(a) monoethylenically unsaturated C
3
-C
8
-carboxylic acids, their anhydrides or mixtures of said carboxylic acids and anhydrides,
(b) compounds with at least two non-conjugated ethylenic double bonds in the molecule as crosslinkers and, where appropriate,
(c) other monoethylenically unsaturated monomers which are copolymerizable with monomers (a) and (b), in the presence of free-radical polymerization initiators and certain surface-active compounds, and to cosmetic or pharmaceutical formulations based on oil-in-water emulsions containing the abovementioned crosslinked copolymers as stabilizer.
DE-B-1 138 225 discloses a process for preparing water-insoluble, water-swellable copolymers by precipitation polymerization of monoethylenically unsaturated carboxylic acids, monomers with at least two non-conjugated ethylenic double bonds in the molecule as crosslinkers and, where appropriate, other water-insoluble monoethylenically unsaturated monomers in the presence of free-radical polymerization initiators and of protective colloids and/or emulsifiers which are soluble both in organic solvents and in water. Thus, for example, precipitation polymerization of acrylic acid and butanediol diacrylate in 1,2-dichloroethane in the presence of polyvinyl ether results in a fine powder which, in ammonia-containing water, forms stiff gels which are suitable as ointment bases for cosmetics. The crosslinked polymers are used in particular as swelling or thickening agents.
DE-A-2 949 843 discloses a process for preparing crosslinked polymers of monoethylenically unsaturated carboxylic acids by free-radical precipitation polymerization of the monomers in the presence of free-radical polymerization initiators and homopolymers of vinylpyrrolidone as protective colloid. The precipitation polymers are used as thickeners in the drugs, cosmetics, paper, textiles, adhesives and emulsion paint sectors.
In the process discosed in DE-A-2 833 468, for example, copolymers of acrylic acid or methacrylic acid and acrylic esters or methacrylic esters are subjected to precipitation polymerization in the presence of ethylene/propylene rubber where appropriate in the presence of crosslinkers. The fine-particle polymers obtainable in this way are used as thickeners in printing pastes, paper coatings and aqueous paint emulsions.
U.S. Pat. No. 4,419,502 discloses the polymerization of monoethylenically unsaturated carboxylic acids in the presence of crosslinkers, free-radical polymerization initiators and polyoxyethylene alkyl ethers and/or polyoxyethylene sorbitan esters in methylene chloride. The surfactants which are also used in the precipitation polymerization serve to control the particle size of the polymers, improve the stirrability of the polymerization mixture and prevent deposits forming in the reaction vessel.
EP-A-0 268 164 discloses storage-stable, rapidly breaking oil-in-water emulsions which comprise a copolymer of acrylic acid with a minor content of a long-chain alkyl acrylate as stabilizer. As stated on page 8 of this citation, permanent stabilization of oil-in-water emulsions is not possible by adding homopolymers of acrylic acid or slightly crosslinked polyacrylic acids.
The earlier non-prior-published DE Application P 4213283.5 discloses the use of copolymers of monoethylenically unsaturated carboxylic acids and long-chain compounds with isolated CC multiple bonds and, where appropriate, further copolymerizable monomers and crosslinkers as thickeners or dispersants, for example in cosmetic or pharmaceutical formulations. The copolymers are prepared by precipitation polymerization.
It is an object of the present invention to provide other stabilizers for oil-in-water emulsions.
We have found that this object is achieved by using crosslinked polymers obtainable by precipitation polymerization of monomer mixtures comprising
(a) monoethylenically unsaturated C
3
-C
8
-carboxylic acids, their anhydrides or mixtures of said carboxylic acids and anhydrides,
(b) compounds with at least two non-conjugated ethylenic double bonds in the molecule as crosslinkers and, where appropriate,
(c) other monoethylenically unsaturated monomers which are copolymerizable with monomers (a) and (b),
in the presence of free-radical polymerization initiators and from 0.1 to 20% by weight, based on the monomers used, of saturated, nonionic surface-active compounds, as stabilizer in oil-in-water emulsions in amounts of from 0.01 to 5% of the weight of the emulsions.
The present invention also relates to cosmetic or pharmaceutical formulations based on oil-in-water emulsions which contain as stabilizer from 0.01 to 5% by weight of crosslinked polymers obtainable by precipitation polymerization of monomers mixtures comprising
(a) monoethylenically unsaturated C
3
-C
8
-carboxylic acids, their anhydrides or mixtures of said carboxylic acids and anhydrides,
(b) compounds with at least two non-conjugated ethylenic double bonds in the molecule as crosslinkers and, where appropriate,
(c) other monoethylenically unsaturated monomers which are copolymerizable with monomers (a) and (b),
in the presence of free-radical polymerization initiators and from 0.1 to 20% by weight, based on the monomers used, of saturated, nonionic surface-active compounds.
Suitable crosslinked copolymers are prepared by precipitation polymerization of monomer mixtures. Component (a) used in the monomer mixtures comprises monoethylenically unsaturated C
3
-C
8
-carboxylic acids, their anhydrides or mixtures of said carboxylic acids and anhydrides. Examples of suitable carboxylic acids are acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid and 2-pentenoic acid. Examples of suitable anhydrides are methacrylic anhydride, maleic anhydride and itaconic anhydride. Monomers of group (a) which are preferably used are acrylic acid, methacrylic acid, maleic acid, maleic anhydride and/or methacrylic anhydride. Monomers (a) can be present, for example, in the mixtures used for the polymerization in amounts of from 50 to 99,99, preferably from 80 to 99,99, % by weight.
Suitable as monomer of group (b) are compounds with at least two non-conjugated ethylenic double bonds in the molecule. Monomers of this type are normally used as crosslinkers in polymerizations. They increase the molecular weight of the resulting copolymers. Examples of suitable crosslinkers are the diacrylates or dimethacrylates of glycols or polyalkylene glycols, such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol methacrylate, diethylene glycol diacrylate or diacrylates or dimethacrylates of polyethylene glycols with molecular weights of up to 2000, divinylbenzene, divinyldioxane, divinylethyleneurea, diallyltartaramide, methylenebisacrylamide, polyhydric alcohols which are esterified at least twice with acrylic acid or methacrylic acid, such as trimethylolpropane, pentaerythritol, 1,4-butanediol, 1,6-hexanediol and sorbitol, trivinylcyclohexane, triallyltriazinetrione, allyl esters of acrylic acid and methacrylic acid, and allyl ethers of polyhydric alcohols, eg. the di- and triallyl ethers of trimethylolpropane, pentaerythritol, sorbitol and sucrose. Crosslinkers which are preferably used are pentaerythritol triallyl ethers, diacrylates or dimethacrylates of glycols or polyethylene glycols with molecular weights of up to 2000, pentaallylsucrose, allyl methacrylate, trimethylolpropane diallyl ether and/or methylenebisacrylamide. The amounts of crosslinker in the monomer mixture are preferably from 0.01 to 20% by weight. In most cases, the monomer mixtures used for the polymerization contain from 0.1 to 2% by weight of crosslinker, it also being possible to use mixtures of different crosslinkers.
Examples are further monoethylenically unsaturated monomers of group (c) suitable for copolymerization with monomers (a) and (b) of N-vinylpyrrolidone, N-vinylcaprolactam, C
1
-C
18
-alkyl (m
Sanner Axel
Schade Christian
Sperling-Vietmeier Karin
Wekel Hans-Ulrich
Westenfelder Horst
BASF - Aktiengesellschaft
Keil & Weinkauf
Sellers Robert E. L.
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