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

Patent metadata

Field	Value
Publication number	US-2016237193-A1
Application number	US-201514829505-A
Country	US
Kind code	A1
Filing date	Aug 18, 2015
Priority date	Feb 15, 2015
Publication date	Aug 18, 2016
Grant date	—

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 the organic solvent was added to the reactor with a risen temperature to 60-130° C. followed by adding molecular weight regulator, and then the mixture of acrylate and initiator was dropped for 1-10 hours. After reaction for 0.5-5 hours at the constant temperature, the organic solvent was removed by vacuum distillation, and then the polymerization product namely polyacrylate was obtained; (2) graft copolymerization: the above polymerization product, water, emulsifier and molecular weight regulator were orderly added to the reactor with a risen temperature to 50-95° C. for stirring 10-30 minutes until homogeneously mixed. Then the fatty acid vinyl ester and initiator aqueous solution with a mass fraction of 5-50% were added respectively for 1-10 hours. After reaction for 1-5 hours at the constant temperature, the temperature was lowered to 25-40° C. and the obtained emulsion mixture was demulsified by adding inorganic salt saturated solution followed by 2-5 times of washing with deionized water, and then the graft copolymerization product was obtained; (3) alcoholysis: the above graft copolymerization product was mixed with alcohol solvent and then added to the reactor with a risen temperature to 30-70° C. followed by adding inorganic base. After alcoholysis for 10-120 minutes, the alcohol solvent and by-products were removed by vacuum distillation, and then the polyacrylate-g-polyvinyl alcohol was obtained after drying; (4) hydrolysis: the above polyacrylate-g-polyvinyl alcohol was mixed with water and then added to the reactor with a risen temperature to 30-70° C. followed by adding inorganic base. After hydrolysis for 10-120 minutes, the water solvent and by-products were removed by vacuum distillation, and then the polycarboxylate superplasticizer solution with a required concentration was finally obtained by adding an appropriate amount of water; wherein in step (1), the organic solvent used in polymerization was methanol, ethanol, p-xylene, 200# solvent oil, glycol, toluene or cyclohexane, with the mass ratio of 2-10:1 to the acrylate; the molecular weight regulator used in polymerization was isopropanol, 1-dodecanethiol or isooctyl 3-mercaptopropionate, with the molar ratio of 0.001-0.05:1 to the acrylate; the acrylate used in polymerization was methyl acrylate, ethyl acrylate, n-propyl acrylate, butyl acrylate or amyl acrylate; the initiator used in polymerization was azobisisobutyronitrile, 2,2′-azobisisoheptonitrile, benzoyl peroxide, tert-butyl hydroperoxide, tert-butyl peroxybenzoate or di-tert-butyl peroxide, with the molar ratio of 0.001-0.05:1 to the acrylate; in step (2), the mass ratio of added water to polyacrylate mentioned in step (1) was 5-50:1; the emulsifier used in graft copolymerization was sodium laurate, sodium dodecyl sulfonate, sodium dodecyl sulfate or sodium stearate, with the molar ratio of 0.00002-0.004:1 to the added water; the molecular weight regulator used in graft copolymerization was 1-dodecanethiol, isopropanol, mercaptoacetic acid or mercaptopropionic acid, with the molar ratio of 0.001-0.05:1 to the fatty acid vinyl ester; the fatty acid vinyl ester used in graft copolymerization was vinyl acetate, vinyl propionate or vinyl butyrate, with the molar ratio of 3-45:1 to the acrylate mentioned in step (1); the solute of initiator aqueous solution used in graft copolymerization was potassium persulfate, sodium persulfate or ammonium persulfate, with the molar ratio of 0.1-0.2:1 to the acrylate mentioned in step (1); the inorganic salt saturated solution used in graft copolymerization was saturated sodium chloride solution, saturated calcium chloride solution or saturated aluminum chloride solution; in step (3), the alcohol used in alcoholysis was methanol, ethanol or propanol, with the molar ratio of 2-5:1 to the fatty acid vinyl ester mentioned in step (2); the inorganic base used in alcoholysis was sodium hydroxide or potassium hydroxide, with the molar ratio of 0.001-0.01:1 to the alcohol; in step (4), the molar ratio of water used in hydrolysis to the acrylate mentioned in step (1) was 2-10:1; the inorganic base used in hydrolysis was sodium hydroxide or potassium hydroxide, with the molar ratio of 0.001-0.01:1 to the water used in hydrolysis.

Assignees

• Univ Beijing Technology

Inventors

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

Classifications

• C08F8/12 Primary

  Hydrolysis · CPC title

• C08F267/06 Primary

  on to polymers of esters · CPC title

• C04B2103/32

  Superplasticisers · CPC title

• C08F265/06

  Polymerisation of acrylate or methacrylate esters on to polymers thereof · CPC title

• C04B2103/006

  Comb polymers · CPC title