Slow-release polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention discloses a slow-release polycarboxylate superplasticizer and a preparation method thereof. The preparation method comprises specific steps as follows: firstly, small unsaturated carboxylic acid monomers and diphenylphosphinyl chloride are subjected to a partial reaction, and small unsaturated monomers containing phosphate ester groups are obtained; then 2-phenylethylamine and phosphate ester groups are added to a reaction system and subjected to a reaction, and small unsaturated monomers containing amide groups are obtained; the small unsaturated monomers containing the amide groups are subjected to an oxidation-reduction free radical polymerization reaction with unsaturated polyether macromonomers under the action of an initiating agent, a reducing agent and a chain transfer agent, and a copolymerization product is obtained; pH value is adjusted to 6-7 after the reaction, water is added, and the polycarboxylate superplasticizer is obtained. The amide groups containing benzene rings are introduced to side chains of the prepared polycarboxylate superplasticizer, so that the dispersibility of the polycarboxylate superplasticizer for cement is improved, the polycarboxylate superplasticizer has good slump retaining performance on the premise of water reduction, and besides, the yield of the polycarboxylate superplasticizer containing the amide groups can reach 94% or higher.

Description

technical field [0001] The invention relates to the technical field of a polycarboxylate water reducer for cement concrete, in particular to a preparation method of a slow-release polycarboxylate water reducer. Background technique [0002] Polycarboxylate water reducer, as a new type of high-performance water reducer following the aliphatic, naphthalene and sulfamate-based water reducers, because of its low dosage, high water-reducing rate, and adjustable molecular structure Excellent properties such as strong tonality and environmental protection have been more and more widely used in a series of concrete projects such as high-speed railways, bridges, tunnels, and dams. The quality of concrete sand and gravel is getting worse (high mud content and stone powder content), etc., polycarboxylate superplasticizers often have some problems in practical applications, and the excessive loss of slump over time is the most common one. main problem. Especially when transporting for...

AI Technical Summary

Problems solved by technology

The water reducing and slump retention properties of the water reducing agent are good, but it is difficult to ensure that there is no esterification reaction by using unsaturated acid anhydride and monohydric alcohol amine for acylation reaction, and the preparation process is relatively complicated, and the process control is difficult. The conversion rate of the prepared amide / imide type polycarboxylate high-performance water reducer is low

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