Polycarboxylic acid and application thereof, and cement water reducing agent containing polycarboxylic acid

Abstract

The invention provides a polycarboxylic acid and application thereof, and a cement water reducing agent containing the polycarboxylic acid, which belongs to the technical field of cement admixtures and can solve the problems of low water reducing rate and overhigh air-entraining property in the existing polycarboxylic acid. The polycarboxylic acid provided by the invention is a random copolymer of the following monomers: 50-80 wt% of unsaturated polyether disclosed as a general formula (I), 15-30 wt% of unsaturated carboxylic acid or unsaturated carboxylate and 0-25 wt% of third monomer with unsaturated double bond and polar group. In the general formula (I), R1 and R2 respectively and independently represent hydrogen atom or methyl group, R3 represents oxopropenyl group, R4 represents oxovinyl group, and R5 and R6 respectively and independently represent hydrogen atom or C1-C20 alkyl group; and a is a whole number ranging from 10 to 50, b and c are respectively and independently a whole number ranging from 30 to 100, and d is a whole number ranging from 0 to 50. The cement water reducing agent provided by the invention contains the polycarboxylic acid. The polycarboxylic acid provided by the invention can be used in the cement water reducing agent.

Description

technical field [0001] The invention relates to the technical field of cement admixtures, in particular to a polycarboxylic acid, the use of the polycarboxylic acid, and a cement water reducer containing the polycarboxylic acid. Background technique [0002] Cement superplasticizer is one of the most important concrete admixtures, which is mainly used to reduce mixing water consumption and improve strength under the condition of concrete workability and cement dosage unchanged. The first-generation and second-generation cement water-reducers are lignosulfonate cement water-reducers and naphthalenesulfonate-formaldehyde condensate cement water-reducers, which can be adsorbed on the surface of cement particles to charge the surface of cement particles. Thus, the cement particles are dispersed by electrostatic repulsion. [0003] Polycarboxylate cement water reducer is the third generation of cement water reducer, it not only can produce electrostatic repulsion, but also has a...

AI Technical Summary

Problems solved by technology

However, the preparation process of the polycarboxylate cement water reducer includes the reaction of unsaturated polycarboxylic acid and polyamide polyamine. In this reaction, the carboxylate radical reacts with the primary amino group to generate double bond polyamide polyamine, It is also possible to react with the primary amine groups at both ends of the polyamide polyamine at the same time to form a structure with double bonds at both ends, or to react with the secondary amine groups in the chain to form a structure with multiple double bonds. These structures will be polymerized in the next step It is easy to form a gel and make the reaction fail, so its preparation is very difficult

[0006] In order to solve the problem that the existing polycarboxylate cement water reducer has too high air entrainment, one method is to compound a certain amount of defoamer, but the solubility of defoamer in polycarboxylate aqueous solution is small, although through Strong shearing can temporarily disperse the defoamer evenly, but because of its poor stability, it will still cause incompatibility after a period of time

In the patent US6187841, the polycarboxylate cement water-reducer with proper air-entraining property is obtained by reducing the ratio of alkoxy polyethylene glycol unsaturated ester and unsaturated acid, but this will reduce the polycarboxylate side chain. Density leading to lower water reduction rate

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