摘要:
The invention relates to a process for the preparation of water-soluble polymers containing polyalkylene glycol ether side chains and having molecular weights of from 15,000 to 65,000 by solution polymerization of esters of ethylenically unsaturated carboxylic acids and polyalkylene glycols which are masked on the end groups at one end, if desired together with another monomer in at least one hydrocarbon at monomer concentrations of from 70 to 95% by weight in the presence of free-radical-forming polymerization initiators and, if desired, polymerization regulators at temperatures of up to 200° C., removal of the solvent used in the solution polymerization, and dissolution of the polymers in water to give from 50 to 80% strength by weight solutions, with polymers containing acid groups being neutralized if desired.
摘要:
A process for the preparation of water-soluble polymers of esters of ethylenically unsaturated carboxylic acids and polyalkylene glycols by azeotropic esterification, in the presence of organic solvents which form an azeotrope with water, of ethylenically unsaturated carboxylic acids with polyalkylene oxides which are capped at one end by end groups, to a degree of at least 85 wt %, followed by free-radical polymerization of the resulting esters optionally together with other ethylenically unsaturated monomers, in aqueous medium, wherein the organic solvents are removed by azeotropic distillation from the reaction mixture during polymerization and the water that is removed by distillation is recycled or the quantity of water removed by distillation from the reaction mixture is replaced by a feed of fresh water.
摘要:
Polymers containing acid groups are modified by reaction of (a) polymers which comprise at least 5% by weight of a copolymerized monoethylenically unsaturated monomer containing acid groups, have molar masses of from 200 to 100,000 and are obtainable by free-radical polymerization of monoethylenically unsaturated acids in aqueous solution in the presence or absence of other monoethylenically unsaturated monomers and in the presence of at least 4% by weight, based on the monomers used in the polymerization, of a water-soluble sulfur compound in which the sulfur is in the oxidation state +4, with (b) polyalkylene glycols which are end-capped at one end, alkylpolyalkylene glycol amines or mixtures thereof, or mixtures of at least one of the two compounds specified with up to 30% by weight, based on the mixtures, of ammonia, amines, alcohols, hydroxycarboxylic acids or aminocarboxylic acids at up to 250° C.
摘要:
Mixtures of at least one polycarboxylate-based plasticizer for cement-comprising mineral building materials, and butoxylated polyalkylenepolyamines or their salts as air detrainers, and the use of such mixtures as additives for mineral building materials comprising cement, are described.
摘要:
Water-soluble polymers of esters made from acrylic acid and alkylpolyalkylene glycols, obtainable by azeotropic esterification of a mixture of acrylic acid and alkylpolyalkylene glycol in a molar ratio of from 2 to 3:1 in the presence of at least 85% by weight, based on the alkylpolyalkylene glycol, of an organic solvent which forms an azeotrope with water, followed by free-radical polymerization, in an aqueous medium, of the mixture obtained during the esterification, where the organic solvent is distilled off azeotropically from the reaction mixture during the polymerization, and the water removed by distillation is returned to the mixture or replaced by a feed of fresh water, and preparation and use of these polymers as an additive to cementitious systems.
摘要:
Alkylpolyalkylene glycol esters of monoethylenically unsaturated carboxylic acids are prepared by esterifying (a) monoethylenically unsaturated carboxylic acids with (b) polyalkylene glycols which are endcapped at one end, in the absence of a solvent and in the presence of polymerization inhibitors and esterification catalysts at not more than 160° C. by a process in which the esterification is first carried out under atmospheric pressure or at up to 50 bar, the water formed in the esterification is then distilled from the reaction mixture at from 10 to 500 mbar and the esterification is then continued under atmospheric pressure or at up to 50 bar.
摘要:
A method for controlling the thickening of aqueous systems comprising silicates, which comprises adding to the aqueous system at least one copolymer of a mean molecular weight Mw of at least 3000 g/mol to at most 60 000 g/mol and the copolymer being made up essentially randomly from monoethylenically unsaturated monocarboxylic acids, monoethylenically unsaturated dicarboxylic acids and other ethylenically unsaturated comonomers, the polymerization for producing the copolymer being performed in the presence of from 0.01 to 100 mol % of at least one base, based on the total amount of all COOH groups of the monocarboxylic and dicarboxylic acids, the quantitative figures in % by weight being respectively based on the total amount of all monomers used.