摘要:
Finely divided, gel-like, water-swellable copolymers are prepared by copolymerizing(a) 100 parts by weight of water-soluble, monoethylenically unsaturated monomers,(b) from 0.01 to 5 parts by weight of monomers containing two or more ethylenically unsaturated double bonds and(c) from 0 to 20 parts by weight of water-insoluble, monoethylenically unsaturated monomersin 20-80% strength by weight aqueous solution in the presence of a polymerization initiator and from 0.1 to 10% by weight, based on the monomers used in the copolymerization, of a surfactant, by a process in which the monomers are copolymerized in the presence of initially from 0 to 50% by weight of the amount of surfactant to a conversion of not less than 60%, the remaining amount of surfactant is then added to the reaction mixture and the copolymerization is completed and the resulting gel particles dried.
摘要:
Finely divided, water-soluble polymers are prepared by polymerization of water-soluble, monoethylenically unsaturated monomers in not less than 20% strength by weight aqueous solution in the presence of a polymerization initiator in a kneader by a process in which from 0.1 to 10% by weight, based on the total monomers, of a surfactant are used in the polymerization, the polymerization initially being carried out to a conversion of the monomers of not less than 60% in the absence of the surfactant or in the presence of not more than 50% of the amount of surfactant, and the remaining amount of surfactant then being added to the reaction mixture and the polymerization completed. The addition of surfactant causes the polymer gel to disintegrate with formation of fine particles.
摘要:
The water absorption capacity of crosslinked, water-swellable polymers is improved by a process in which a water-containing, finely divided polymer gel having a solids content of from 20 to 65% by weight is treated with steam at not less than 50.degree. C., the solids content of the water-containing polymer gel increasing by not more than 30% by weight, and the polymer gel is then dried in a conventional manner.
摘要:
Polymers in bead form are prepared from water-soluble ethylenically unsaturated monomers by a reverse suspension polymerization of a liquid in the presence of polymerization initiators and protective colloids obtainable by grafting polymers (A) containing (a) aromatic monovinyl monome from 40 to 100% by weight (b) C.sub.3-6 monoethylenically unsaturated carboxylic acid and/or maleic anhydride from 0 to 60% by weight (c) other monoethylenically unsaturated monomers from 0-20% by weight, as copolymerized units with the proviso that the sum of the weight (a) to (c) is always 100 and the polymer (A) has a molecular weight (number average) from 500 to 20,000 and a hydrogenation iodine number from 1.3 to 51 with a fixed monomer mixture at given concentration levels.
摘要:
A process is described for the preparation of finely divided polymer powders by polymerizing water-soluble monomers in the aqueous phase of a water-in-oil emulsion in the presence of water-in-oil emulsifiers and polymerization initiators, removing the water from the resultant water-in-oil polymer suspension by azeotropic distillation, and isolating the suspended, finely divided polymer powder, either the polymerization of the water-soluble monomers being carried out in the presence of from 0.1 to 10% by weight, based on the monomers employed in the polymerization, of protective colloids, or the protective colloids being added to the water-in-oil polymer suspension after the polymerization is complete. The polymerization is preferably carried out in the presence of surfactant. The finely divided pulverulent polymers are used as flocculants or thickeners for aqueous systems.
摘要:
In a cationic modification process for starch, starch is reacted with polymers that contain amino and/or ammonium groups in an aqueous medium at temperatures from 115.degree. C. to 180.degree. C. under an increased pressure and in the absence of oxidizers, polymerization initiators and alkali. The reaction is conducted so that maximum 10% by weight starch has its molar weight reduced. Also disclosed is the use of the thus obtained reaction products as dry strength agents for paper.
摘要:
Abstract of the Disclosure: Crosslinked acrylic or methacrylic acid copolymers with crosslinkable groups that are useful as thickeners for textile print pastes are obtainable by copolymerization of(a) from 50 to 99 parts by weight of acrylic acid and/or methacrylic acid,(b) from 1 to 50 parts by weight of at least one N-methylol (meth)acrylamide or derivatives thereof,(c) from 50 to 10,000 ppm, based on the monomers (a) and (b), of an at least bifunctional crosslinker, and(d) from 0 to 49 parts by weight of other monoethylenically unsaturated monomersin the presence of a free radical polymerization initiator in the aqueous phase of a water-in-oil emulsion.
摘要:
Paper, board and cardboard are produced by draining a pulp slurry in the presence of high molecular weight, water-soluble polymers of N-vinylamides as drainage aids, retention agents and flocculants. These polymers are particularly effective in a pulp slurry which has a high content of interfering substances and other phenolic compounds.
摘要:
Bead polymers are prepared by reverse suspension polymerization by a process in which an aqueous solution of water-soluble ethylenically unsaturated monomers are polymerized in an aliphatic hydrocarbon using an inorganic suspending agent based on a modified finely divided mineral and, in addition, from 0.1 to 5% by weight, based on the monomers used, of a nonionic surfactant, in the presence of a polymerization initiator, with the formation of a water-in-oil polymer suspension.
摘要:
Concentrated aqueous solutions of quaternization products of tertiary aminoalkyl esters or tertiary aminoalkylamides of acrylic or methacrylic acid are prepared by reaction of the corresponding esters or amides with an alkylating agent in a water-soluble ketone as solvent, by a process wherein, in order to isolate the quaternization product, an amount of water is added to the reaction mixture such that two phases form, and the lower aqueous phase, which contains the quaternization product in solution, is separated from the upper phase, which contains the ketone and residual alkylating agent.