Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-10-11
2002-04-09
Zitomer, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C210S705000, C210S723000, C210S734000, C526S307100, C526S307300, C526S307700, C526S310000, C526S312000, C526S326000
Reexamination Certificate
active
06369182
ABSTRACT:
TECHNICAL FIELD
This invention concerns cationic latex terpolymer flocculants and their use for waste water treatment.
BACKGROUND OF THE INVENTION
It is well known that the clarification or dewatering of sewage and industrial sludges and similar organic suspensions may be aided by chemical reagents, added in order to induce a state of coagulation or flocculation which facilitates the process of solid/liquid or liquid/liquid separation from water. For this purpose, lime or salts of iron or aluminum have been utilized. More recently synthetic polyelectrolytes, particularly certain cationic latex flocculants such as copolymers of acrylamide and dimethylaminoethylacrylate, have been found to be of interest.
These types of polymers are broadly termed coagulants and flocculants. These polymers can be utilized in such diverse processes as emulsion breaking, sludge dewatering, raw water clarification, drainage and retention aids in the manufacture of pulp and paper, flotation aids in mining processing and color removal.
In the water treatment field of solids/liquid separation, suspended solids are removed from water by a variety of processes, including sedimentation, straining, flotation, filtration, coagulation, flocculation, and emulsion breaking among others. Additionally, after suspended solids are removed from the water they must often be dewatered so that they may be further treated or properly disposed of Liquids treated for solids removal often have as little as several parts per billion of suspended solids or dispersed oils, or may contain large amounts of suspended solids or oils. Solids being dewatered may contain anywhere from 0.25 weight percent solids, to 40 or 50 weight percent solids material. Solids/liquid or liquid/liquid separation processes are designed to remove solids from liquids, or liquids from liquids.
While strictly mechanical means have been used to effect solids/liquid separation, modern methods often rely on mechanical separation techniques that are augmented by synthetic and natural polymeric materials to accelerate the rate at which solids can be removed from water. These processes include the treatment of raw water with cationic coagulant polymers that settle suspended inorganic particulates and make the water usable for industrial or municipal purposes. Other examples of these processes include the removal of colored soluble species from paper mill effluent wastes, the use of organic flocculant polymers to flocculate industrial and municipal waste materials, sludge recovery and emulsion breaking.
A benchmark test for evaluating the effectiveness of a flocculant is the so-called drainage test in which the polymer is added to sludge and mixed so that the polymer flocculates the sludge. The mixture is then poured through a belt filter press cloth and the rate at which water drains is taken as a measure of polymer performance.
Regarding the mechanism of separation processes, particles in nature have either a cationic or anionic charge. Accordingly, these particles often are removed by a water-soluble coagulant or flocculent polymer having a charge opposite to that of the particles. This is referred to as a polyelectrolyte enhanced solids/liquid separation process, wherein a water-soluble or dispersible ionically charged polymer is added to neutralize the charged particles or emulsion droplets to be separated. The dosage of these polymers is critical to the performance of the process. Too little ionically charged polymer, and the suspended particles will not be charge neutralized and will thus still repel each other. Too much polymer, and the polymer will be wasted, or worse, present a problem in and of itself.
Notwithstanding the variety of commercially available polymers that have been found to be capable of flocculating or coagulating solids sludges, there are various circumstances which tend to limit the usefulness of these reagents. While for certain sludges economical treatments with these known reagents are feasible, more often sludges require very high and cost-ineffective dosages of reagents for successful treatment. Moreover, variations often occur in sludge from any one source. For example, variations in the supply of material to the waste water/sludge/paper furnish process water and/or in the oxidizing conditions that may be involved in the production of these waters lead to a variety of particle types which must be removed. Furthermore, it is not uncommon to encounter sludges that are, for some reason, not amenable to flocculation by any of the known polymeric flocculating agents.
Therefore, there is a need for an improved family of polymers that provide better drainage at lower doses than the currently-available acrylamide/dimethylaminoethylacrylate copolymers.
SUMMARY OF THE INVENTION
We have discovered new cationic terpolymers which are 15 to 20 percent more efficient than currently-available acrylamide/dimethylaminoethylacrylate copolymers.
Accordingly, in its principle aspect, this invention is directed to a cationic terpolymer comprising
(a) a first monomer unit selected from acrylamide and methacrylamide;
(b) a second monomer unit selected from dimethylaminoethyl acrylate methyl chloride quaternary salt, 3-(acrylamido)propyltrimethylammonium chloride, 3-(methacrylamido)propyltrimethylammonium chloride, dimethylaminoethyl methacrylate methyl chloride quaternary salt, dimethylaminoethyl acrylate dimethylsulfate quaternary salt, dimethylaminoethyl methacrylate dimethylsulfate quaternary salt, diethylaminoethyl acrylate methyl chloride quaternary salt and diethylaminoethyl acrylate dimethylsulfate quaternary salt; and
(c) a third monomer unit selected from benzyl methacrylate, 2,2,2-trifluoroethyl acrylate, acrylamide diacetone, N-phenylacrylamide, 2,2,3,3-tetrafluoropropyl acrylate and poly(propylene glycol)methacrylate.
DETAILED DESCRIPTION OF THE INVENTION
Definitions of Terms
As used herein, the following abbreviations and terms shall have the following meanings:
“ADA” means diacetone acrylamide, available from Chemie Linz U.S. Inc., Fort Lee, N.J.
“Alfonic®1412-60” is a ethoxylated linear alcohol (60% ethylene oxide), available from Vista Chemical Co., Houston, Tex.
“AM” for acrylamide.
“AIBN” for 2,2′-azobis(isobutyronitrile), available from E.I. duPont Nemours & Co. Inc.; Wilmington, Del.
“AIVN” for 2,2′-azobis(2,4-dimethylvaleronitrile), available from E.I. duPont Nemours & Co. Inc.; Wilmington, Del.
“DMAEA” for dimethylaminoethyl acrylate.
“DMAEM” for dimethylaminoethyl methacrylate.
“DMAEA.MCQ” for dimethylaminoethyl acrylate, methyl chloride quaternary salt.
“EDTA.4Na+” for ethylenediaminetetraacetic acid, tetrasodium salt.
“NaCl” for sodium chloride.
“NaNO
3
” for sodium nitrate.
“POE” for polyoxyethylene.
“PPG” for poly(propylene glycol).
“Span 80” for sorbitan monooleate from ICI Specialty Chemicals, Wilmington, Del.
“Triton®N-101” for Nonylphenoxy polyethoxy ethanol, available from Rohm and Haas Co., Philadelphia, Pa.
“Tween 61” for POE (4) sorbitan monostearate, available from ICI Specialty Chemicals, Wilmington, Del.
“
1
H-NMR” for Proton Nuclear Magnetic Resonance Spectroscopy.
“rpm” for revolutions-per-minute.
“Chain Transfer Agent’ means any molecule, used in free-radical polymerization, which will react with a polymer radical forming a dead polymer and a new radical. Representative Chain Transfer Agents are listed by K. C. Berger and G. Brandrup, “
Transfer Constants to Monomer, Polymer, Catalyst, Solvent, and Additive in Free Radical Polymerization
, ” Section II, pp. 81-151, in “
Polymer Handbook
, ” edited by J. Brandrup and E. H. Immergut, 3d edition, 1989, John Wiley & Sons, New York.
“Inverse emulsion polymer” and “inverse latex polymer” mean a water-in-oil polymer emulsion comprising a cationic terpolymer according to this invention in the aqueous phase, a hydrocarbon oil for the oil phase and a water-in-oil emulsifying agent. Inverse emulsion polymers are hydrocarbon continuous with the water-soluble polymers dispersed within the hydrocarbon matrix. The inverse emulsion polymers are then “inver
Sivakumar Ananthasubramanian
Whipple Wesley L.
Breininger Thomas M.
Martin Michael B.
Nalco Chemical Company
Zitomer Fred
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