Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-07-06
2001-02-06
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...
C526S229000, C526S303100, C526S317100
Reexamination Certificate
active
06184321
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing homopolymers and/or copolymers, in an aqueous solution of ethylenically monounsaturated monomers, e.g. acrylic and/or vinylic monomers, such that, for each monomer, one can achieve a residual monomer concentration less than or equal to 300 ppm (based on the weight of the raw product), wherewith the concentration of the products is at least 38%; and wherewith these results can be achieved regardless of the monomer(s) used, and at the end of the polymerization, without the need for any intervening treatment.
The invention also relates to the homopolymers and/or copolymers manufactured by the described method; and the use of said homopolymers and/or copolymers, as:
milling agents and/or dispersants in aqueous suspensions of mineral materials; or
sequestering agents and/or precipitation inhibitors and/or inhibitors of mineral incrustation (particularly with respect to heat transfer surfaces in industrial or household systems); or
fluidifying agents for aqueous suspensions based on non-saline or saline water, which suspensions are used as drilling fluids (muds) and the like in the areas of civil engineering, construction, public works, minerals prospecting, and petroleum production; or
stabilizers for suspensions of zeolites; or anti-scaling agents and dispersant agents, in detergent formulations containing hypochlorite compounds, wherewith the subject polymers do not destabilize the “chlorometric index” of said hypochlorite compounds; or
“builders” in detergent compositions; or
water retention agents in the paper industry.
The invention further relates to the abovementioned aqueous suspensions of mineral materials, having characteristics of long term stability and high concentrations of the mineral materials; and the use of the suspensions in areas such as paper, paints and other coatings, detergents and other cleaning agents, ceramics, mineral drilling and production (e.g. drilling-mud compositions), and other sectors which employ such suspensions.
2. Description of the Background
Various methods have long been known for homopolymerization, in solution, of acrylic and/or vinylic monomers, e.g. (meth)acrylic acid, maleic anhydride, and acrylamide; and for copolymerization, in aqueous solution, of acrylic acid with monoethylenically unsaturated comonomers such as, e.g., maleic anhydride, itaconic acid, acrylamide, (acrylamidomethyl)propanesulfonic acid, and acrylate esters. However, none of these methods is entirely satisfactory in the light of current and/or expected environmental regulations, particularly regulations governing the residual monomer content in the polymer in a given application, or requirements as to the color and/or odor of the product.
Eur. Pats. 0,668,298 and 0,608,845 describe methods of copolymerization which, unless subsequent treatments are employed, result in residual monomer contents which exceed 1000 ppm. These methods would not meet the standards demanded in the current market.
Eur. Pat. 0,618,240 discloses a method enabling production of polymers with lower residual monomer content, as do Eur. Pats. 0,398,724, 0,510,831, and 0,663,408; however, all have fundamental practical disadvantages connected with the method, or disadvantages such as:
the use of metallic salts which promote decomposition reactions of hydrogen peroxide, e.g. the Fenton reaction, which often result(s) in ultimate products which are undesirably colored and which contain metal salts which are environmental pollutants;
the use of persulfates which undergo decomposition because of the application of heat or because of redox reactions, resulting in ultimate products which undesirably contain sulfur; and
the use of organic initiators, e.g. organic peroxides, particularly benzoyl peroxide, which result in the production of undesirable by-products such as certain nitrogen compounds.
U.S. Pat. No. 4,301,266 discloses a method of manufacturing acrylic acid polymers, with the disadvantage that one must use a solvent of the isopropanol type and must operate at elevated pressure.
Also known to those skilled in the art is U.S. Pat. No. 4,621,127, which discloses a method of copolymerization. The method is costly and lengthy, and requires the use of chain regulators to prepare low molecular weight polymers.
SUMMARY OF THE INVENTION
Accordingly, one object of the invention is to provide a method which enables the production of dissolved polymers which are colorless, odorless, and which are accompanied by very low (minimum) amounts of residual monomers and undesirable organic by-products.
Another object of the invention is to provide a milling agent and/or dispersant for aqueous suspensions of mineral materials, which enables production of concentrated aqueous dispersions of mineral particles, which dispersions have relatively low viscosity and are durably stable even without agitation.
Still another object of the invention is to provide a sequestering agent and/or precipitation inhibitor and/or inhibitor of mineral incrustation, using a copolymer of the described type having a molecular weight low enough to be adapted to such applications.
Yet another object of the invention is to provide
a fluidifying agent for aqueous suspensions which are used as drilling fluids (muds) and the like; or
a stabilizer for suspensions of zeolites; or
an anti-scaling agent and dispersant agent, for use in detergent formulations containing hypochlorite compounds, wherewith said agent does not destabilize the “chlorometric index” of said hypochlorite compounds; or
a “builder” for detergent compositions and the like.
Still another object of the invention is to provide aqueous suspensions in paper pulp processing, processing of pastes and slurries in sugar manufacture, paper coating, ceramics manufacture, detergent formulation, and formulation of drilling muds and the like.
Briefly, these objects and other objects of the present invention as hereinafter will become more readily apparent can be attained in a method of polymerization in which compounds containing a phosphorus atom, having a degree of oxidation less than 5, are introduced in amounts corresponding to 0.005-0.49 gram-atom phosphorus per mol of unsaturation in the monomer(s) to be polymerized, into the reaction vessel or into the starting monomer mixture in the reaction vessel as into the reaction vessel, prior to the start of the polymerization, said introduction occurring:
in the presence of hydrogen peroxide and
in the absence of any agents, which decompose hydrogen peroxide to form free radicals, such as metals or metal salts, which agents are deemed necessary by the art to satisfactorily achieve such decomposition, further, in the absence of any other generator of free radicals, and in the absence of any per salt and/or any other transfer agent.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Whereas the prior art to which the present invention relates describes methods of polymerization which make use of decomposition reactions of hydrogen peroxide of the type of the Fenton reaction, or employs reactions of thermal or redox decomposition of initiators currently in use, it has now been found, and quite surprisingly, that the use of a compound containing a phosphorus atom of degree of oxidation less than 5, when introduced in amounts corresponding to 0.005-0.49 g-atom phosphorus per mol of unsaturation in monomers in an aqueous reaction medium enables:
homopolymerization of a monomer such as (meth)acrylic acid or maleic acid, or
copolymerization of maleic acid or a copolymerizable monomer, with acrylic acid or a copolymerizable monomer, with the addition solely of hydrogen peroxide, without the presence of agents which promote decomposition of hydrogen peroxide to form free radicals, e.g. metals or metal salts, such as salts of Cu, Fe, Co, Ni, Zn, W, Ce, Mo, Zr, or mixtures of these, which agents are deemed necessary in the art in order to satisfactorily achieve such decomposition, e.g. in the familiar Fenton reaction, and further without the
Egraz Jean-Bernard
Kensicher Yves
Suau Jean-Marc
Coatex S.A.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Zitomer Fred
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