Controllable method for preparing methoxy polyethylene glycol methacrylate-styrene polymer under condition of high vacuum degree

Abstract

Disclosed is a method for preparing methoxy polyethylene glycol methacrylate-styrene polymer under high controllable vacuum degree, relating to the technical field of the synthesis of organic macromolecule through chemical esterification. The method takes methoxy polyethylene glycol at certain polymerization degree and methacrylic acid as raw materials, 4-dimethylaminopyridine as catalyzer and at least one of nitroxyl radical piperidone, toluquinone and hydroquinone as retardant. When the reaction begins, the methacrylic acid in which the retardant is dissolved is added into the reaction kettle drop by drop within 1-3 hours, and water produced in the esterification process is brought away through specific controllable vacuum degree, thus pushing the reaction equation forward towards the positive direction; wherein the specific vacuum degree and the reaction temperature are key factors for controlling the esterification rate and the reaction temperature depends on the vacuum degree of the system. The invention prepares methoxy polyethylene glycol methacrylate-styrene polymer through controllable vacuum degree mode and is moderate in reaction conditions and does not use organic solvent, thus avoiding the step of post processing.

Description

technical field [0001] The invention relates to the field of organic polymer chemistry, in particular to an esterification method for preparing methoxypolyethylene glycol methacrylate under controllable high vacuum. Background technique [0002] Polycarboxylate water reducer is a new type of high-efficiency water reducer and a core technical material in the preparation of high performance concrete. Compared with the first two generations of lignosulfonate ordinary water reducers and the second generation of high-efficiency water reducers represented by naphthalene and melamine, polycarboxylate high-performance water reducers have hyperdispersibility and can prevent Concrete loses slump over time, does not cause obvious retardation, and has the characteristics of low dosage, high water-reducing performance, and environmental protection. The performance of the water reducer can be adjusted through molecular design, selection of monomer type and ratio, polymerization process c...

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Problems solved by technology

Propose to adopt solid acid to do catalyst among CN101092478A, replace homogeneous catalyst, although overcome the problem of catalyst recovery difficulty, still adopt azeotropic solvents such as hexanaphthene to carry water

The method of passing nitrogen has a limited entrainment effect on water, and can only take away part of the water; although in patent CN101117378A, the method of nitrogen passing and vacuuming is combined, but the highest vacuum proposed is only between 0.090MPa and 0.096MPa. Therefore, its entrainment effect on water still has certain limitations, especially when the viscosity of the system increases (the degree of polymerization of methoxypolyethylene glycol is greater than 45), the water generated by esterification is more difficult to be extracted, so CN 101117378A and CN 101117381A all require that the polymerization degree of raw material methoxypolyethylene glycol is controlled at 5~45

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