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
1998-03-11
2001-07-17
Reddick, Judy M. (Department: 1713)
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...
C524S401000, C524S416000, C524S417000, C524S419000, C524S423000, C524S436000, C524S456000, C524S458000, C524S460000, C524S519000, C524S522000
Reexamination Certificate
active
06262168
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to aqueous dispersions comprised of water-soluble and/or water-swellable copolymers, processes for making said dispersions, and methods of using said dispersions in water treating, dewatering, water clarification, papermaking, oil field, soil conditioning, food processing, mineral processing, and biotechnological applications.
Aqueous dispersions of water-soluble and water-swellable polymers are known, see generally e.g. U.S. Pat. No. 5,696,228, which is hereby incorporated herein by reference, and references therein. In this regard may also be mentioned U.S. Pat. No. 5,708,071 and EP 0 717 056 A2, which disclose aqueous dispersions of amphoteric polymers. Aqueous dispersions typically consist of a discontinuous polymer-containing phase and a continuous aqueous phase. The discontinuous phase may contain water and generally contains a water-soluble or water-swellable polymer, and the continuous aqueous phase usually contains a different water-soluble polymer and/or salt. Despite efforts to make satisfactory aqueous dispersions, the problem remains of producing aqueous dispersions of water-swellable and high molecular weight water-soluble polymers that have advantageously low bulk viscosities, high active solids content, minimal quantities of dilutive material, and that dissolve readily and can be prepared with a broad range of cationicity.
SUMMARY OF THE INVENTION
This problem is solved in the present invention by providing novel aqueous dispersions of high molecular weight water-soluble or water-swellable polymers, as well as processes for making and methods of using said aqueous dispersions. Accordingly, an aqueous dispersion of polymers is provided which comprises (a) a first cationic water-soluble or water-swellable polymer comprised of cationic recurring units and anionic recurring units; and (b) at least one second water-soluble polymer different from said first polymer, wherein the amounts of said (a) and said (b) are such that a homogeneous composition is obtained in the absence of said (b).
Processes for making aqueous dispersions are also provided, e.g. a process which comprises copolymerizing a mixture of monomers comprised of cationic vinyl-addition monomer and anionic vinyl-addition monomer to form a first cationic water-soluble or water-swellable polymer which contains bulk viscosity-reducing amounts of anionic recurring units, wherein said polymerizing is carried out in the presence of a dispersion-creating amount of at least one second water-soluble polymer different from said first polymer.
Methods of using aqueous dispersions to treat suspended solids are also provided e.g. a method for dewatering a suspension of dispersed solids which comprises intermixing an aqueous dispersion of polymers, or aqueous admixture thereof, in an amount effective for dewatering, with a suspension of dispersed solids, and dewatering said suspension of dispersed solids, wherein said aqueous dispersion of polymers is comprised of (a) a first cationic water-soluble or water-swellable polymer comprised of cationic recurring units and anionic recurring units; and (b) at least one second water-soluble polymer different from said first polymer, in which the amounts of said (a) and said (b) are such that a homogeneous composition is obtained in the absence of said (b).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The aqueous dispersions of the instant invention are generally comprised of a discontinuous phase of small aqueous droplets, containing polymer that is comprised predominately of a first cationic water-soluble or water-swellable polymer, that are dispersed in an aqueous continuous phase, although of course minor amounts of said first polymer may be found in the continuous phase. Typically more than 50%, preferably more than 75%, of the polymer in a typical small aqueous droplet is the first cationic water-soluble or water-swellable polymer. The amount of first cationic polymer in the discontinuous and continuous phases may be determined by known analytical techniques e.g. Raman microscopy.
The first cationic water-soluble or water-swellable polymer may be a condensation polymer or an addition polymer, preferably a vinyl-addition polymer. The cationic charge of said first cationic polymer may vary over a broad range by containing from about 1% to about 99.9% cationic recurring units, preferably about 5% or greater, more preferably about 10% or greater, even more preferably about 20% or greater, most preferably about 30% or greater, preferably about 90% or less, more preferably about 80% or less, most preferably about 70% or less, by mole based on total moles of recurring units in said first cationic polymer. Cationic recurring units may be formed by post-reaction of polymer, but are preferably formed by polymerization of cationic monomers. Cationic monomers may include any cationic monomer, including diallyidialkylammonium halide, cationic (meth)acrylates, and cationic (meth)acrylamides commonly used in preparing water-soluble polymers, preferably diallyidimethylammonium halide, as well as acid and quaternary salts of dialkylaminoalkyl(alk)acrylate and dialkylaminoalkyl(alk)acrylamide. Cationic recurring units may be formed by the polymerization of quaternizable monomers such as dialkylaminoalkyl(alk)acrylate or dialkylaminoalkyl(alk)acrylamide, followed by acidification or quaternization. Most preferably, the first cationic polymer contains cationic recurring units of the formula (I), preferably formed by polymerization of the corresponding monomers of the formula (II):
wherein R
1
is H or CH
3
, A is O or NH, B is alkylene or branched alkylene or oxyalkylene having from 1 to 5 carbons, R
2
and R
3
are each individually methyl, ethyl, or propyl, R
4
is an alkyl group having from 1 to 10 carbon atoms, or an aryl group having from 6 to 10 carbon atoms, and X is a counterion. In more preferred embodiments, R
2
, R
3
and R
4
together contain at least a total of 4 carbon atoms. In certain preferred embodiments, R
4
is a methyl, ethyl or propyl group. In other preferred embodiments, R
4
is an alkyl group having from 4 to 10 carbon atoms. In other preferred embodiments, R
4
is benzyl. Preferably, X is chloride, bromide, iodide, methylsulfate, or ethylsulfate. Recurring units of the formula (I) are even more preferably (meth)acryloyloxyethyltrimethylammonium chloride, (meth)acryloyloxyethyltrimethylammonium methyl sulfate, (meth)acryloyloxyethyldiethyl-methylammonium chloride, (meth)acryloyloxyethyidiethylmethylammonium methyl sulfate, (meth)acryloyloxyethyldimethylbenzylammonium chloride, and (meth)acryloyloxyethyl-dimethylbenzylammonium methyl sulfate; i.e. A═O, B═CH
2
CH
2
, R
1
═H or CH
3
, R
2
═R
3
═CH
2
CH
3
or CH
3
, R
4
═CH
3
or benzyl, and X ═CI or CH
3
SO
4
. Most preferably, recurrin units of the formula (I) are acryloyloxyethyidiethylmethylammonium methyl sulfate (A═O, B═CH
2
CH
2
, R
1
═H, R
2
═R
3
═CH
2
CH
3
, R
4
═CH
3
, X═CH
3
SO
4
) and acryloyloxyethyl trimethylammonium chloride (AETAC) (A ═O, B═CH
2
CH
2
, R
1
═H, R
2
═R
3
═R
4
═CH
3
, X═CI). For the purposes of the instant invention, recurring units may be referred to by the name of the corresponding monomer.
The first cationic water-soluble or water-swellable polymer is a copolymer and contains anionic recurring units. Surprisingly, the inclusion of even very small amounts of anionic recurring units may have the unexpected effect of inducing the formation of the aqueous dispersion and/or reducing the bulk viscosity of the aqueous dispersion. For instance, if an aqueous dispersion is not formed in a mixture of a first cationic polymer that does not contain anionic recurring units and a second water-soluble polymer, the inclusion of dispersion-creating amounts of anionic recurring units into the first cationic polymer causes an aqueous dispersion to result. Also, if an aqueous dispersion having a particular bulk viscosity is formed in a mixture of a f
Huang Sun-Yi
Kozakiewicz Joseph J.
Rosati Louis
Cytec Technology Corp.
Knobbe Martens Olson & Bear LLP
Reddick Judy M.
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