Method for preparation of polycarboxylate superplasticizer by graft copolymerization of fatty acid vinyl ester onto acrylate polymer

Patent metadata

Field	Value
Publication number	US-9453097-B2
Application number	US-201514829505-A
Country	US
Kind code	B2
Filing date	Aug 18, 2015
Priority date	Feb 15, 2015
Publication date	Sep 27, 2016
Grant date	Sep 27, 2016

Abstract

This invention relates to a method for preparing a polycarboxylate superplasticizer by graft copolymerization of fatty acid vinyl ester onto acrylate polymer. In this invention, a type of polycarboxylate superplasticizer by graft copolymerization of fatty acid vinyl ester onto acrylate polymer was synthesized by the processes of polymerization-grafting-alcoholysis-hydrolysis with acrylate and fatty acid vinyl ester as main reactants. In the first polymerization step, the polyacrylate was synthesized by using acrylate as monomer and a certain amount of initiator and molecular weight regulator. In the second graft copolymerization step, the graft polymer with polyacrylate as main chain and poly(fatty acid vinyl ester) as side chain was synthesized by graft copolymerization between polyacrylate and fatty acid vinyl ester. The final polycarboxylate superplasticizer product with polyacrylic acid as main chain and polyvinyl alcohol as side chain was obtained by subsequent alcoholysis and hydrolysis steps. The preparation process of this invention exhibited some characteristics including simpleness, easy controlling, low cost, environmental friendliness and pollution free. The fatty acid vinyl ester was as a reactant instead of conventional polyethylene glycol macromonomer, which enriched the applicable scope of reactive raw materials. The prepared polycarboxylate superplasticizer showed good cement paste fluidity and fluidity retention, which manifested as good adaptability to cement and application performance in concrete.

First claim

What is claimed is:

1. A preparation method of a polycarboxylate superplasticizer by graft copolymerization of fatty acid vinyl ester onto acrylate polymer, comprising a polymerization step, a graft copolymerization step, an alcoholysis step and a hydrolysis step in sequence, wherein:
(1) polymerization: firstly an organic solvent is added to a reactor with an elevated temperature to 60-130° C. followed by adding a first molecular weight regulator, and then a mixture of acrylate and initiator is dropped for 1-10 hours; after reaction for 0.5-5 hours at constant temperature, the organic solvent is removed by vacuum distillation, and then a polymerization product is obtained;
(2) graft copolymerization: the polymerization product, water, emulsifier and a second molecular weight regulator are orderly added to the reactor with an elevated temperature to 50-95° C., stirring for 10-30 minutes until homogeneously mixed; then a fatty acid vinyl ester and an initiator aqueous solution with a mass fraction of 5-50% are added respectively for 1-10 hours; after reaction for 1-5 hours at constant temperature an emulsion mixture is obtained, the temperature is lowered to 25-40° C. and the emulsion mixture is demulsified by adding an inorganic salt saturated solution followed by 2-5 times of washing with deionized water, and then a graft copolymerization product is obtained;
(3) alcoholysis: the graft copolymerization product is mixed with an alcohol solvent and then added to the reactor with an elevated temperature to 30-70° C. followed by adding an inorganic base; after alcoholysis for 10-120 minutes, the alcohol solvent and by-products are removed by vacuum distillation, and then a polyacrylate-g-polyvinyl alcohol is obtained after drying;
(4) hydrolysis: the polyacrylate-g-polyvinyl alcohol is mixed with water and then added to the reactor with an elevated temperature to 30-70° C. followed by adding another inorganic base; after hydrolysis for 10-120 minutes, the water and by-products are removed by vacuum distillation, and then a polycarboxylate superplasticizer solution is obtained by adding water;
wherein in step (1), the organic solvent used in polymerization comprises methanol, ethanol, p-xylene, glycol, toluene or cyclohexane, with a mass ratio of the organic solvent to the acrylate being 2-10:1; the first molecular weight regulator used in the polymerization comprises isopropanol, 1-dodecanethiol or isooctyl 3-mercaptopropionate, with a molar ratio of the first molecular weight regulator to the acrylate being 0.001-0.05:1; the acrylate used in the polymerization comprises methyl acrylate, ethyl acrylate, n-propyl acrylate, butyl acrylate or amyl acrylate; the initiator used in the polymerization comprises azobisisobutyronitrile, 2,2′-azobisisoheptonitrile, benzoyl peroxide, tert-butyl hydroperoxide, tert-butyl peroxybenzoate or di-tert-butyl peroxide, with a molar ratio of the initiator to the acrylate being 0.001-0.05:1;
in step (2), a mass ratio of added water to the polymerization product in step (1) is 5-50:1; the emulsifier used in the graft copolymerization comprises sodium laurate, sodium dodecyl sulfonate, sodium dodecyl sulfate or sodium stearate, with a molar ratio of the emulsifier to the added water being 0.00002-0.004:1; the second molecular weight regulator used in the graft copolymerization comprises 1-dodecanethiol, isopropanol, mercaptoacetic acid or mercaptopropionic acid, with a molar ratio of the second molecular weight regulator to the fatty acid vinyl ester being 0.001-0.05:1; the fatty acid vinyl ester used in the graft copolymerization comprises vinyl acetate, vinyl propionate or vinyl butyrate, with a molar ratio of the fatty acid vinyl ester to the acrylate in step (1) being 3-45:1; solute of the initiator aqueous solution used in the graft copolymerization comprises potassium persulfate, sodium persulfate or ammonium persulfate, with a molar ratio of the solute to the acrylate mentioned in step (1) being 0.1-0.2:1; the inorganic salt saturated solution used in the graft copolymerization comprises saturated sodium chloride solution, saturated calcium chloride solution or saturated aluminum chloride solution;
in step (3), the alcohol used in the alcoholysis comprises methanol, ethanol or propanol, with a molar ratio of the alcohol to the fatty acid vinyl ester in step (2) being 2-5:1; the inorganic base used in the alcoholysis comprises sodium hydroxide or potassium hydroxide, with a molar ratio of the inorganic base to the alcohol being 0.001-0.01:1;
in step (4), a molar ratio of water used in the hydrolysis to the acrylate in step (1) is 2-10:1; the another inorganic base used in the hydrolysis comprises sodium hydroxide or potassium hydroxide, with a molar ratio of the another inorganic base to the water used in the hydrolysis being 0.001-0.01:1.

Assignees

• Univ Beijing Technology

Inventors

• Liu Xiao
• Wang Ziming
• Zhao Ming
• Cui Suping
• Lan Mingzhang

Classifications

• C08F8/12 Primary

  Hydrolysis · CPC title

• C08F265/00

  Macromolecular compounds obtained by polymerising monomers on to polymers of unsaturated monocarboxylic acids or derivatives thereof as defined in group C08F20/00 · CPC title

• C08F267/06 Primary

  on to polymers of esters · CPC title

• C08F265/04 Primary

  on to polymers of esters · CPC title

• C08F8/06

  Oxidation · CPC title