A kind of synthetic method of solid polycarboxylate water reducer

Abstract

The invention belongs to the technical field of concrete admixtures, and relates to a method for synthesizing a solid polycarboxylic acid water reducer. The method mainly comprises the following steps: adding liquid polyether A and phthalic anhydride into a first reaction container, and preparing monopolyether phthalate; adding a first part of the monopolyether phthalate and an unsaturated polyether macromonomer into a second reaction container; preparing a solution B and a solution C in parallel; dropwise adding the solution B and the solution C into the second reaction container at a constant speed, adding p-toluenesulfonic acid after the addition, and carrying out an esterification reaction; and adding an inorganic strong base to adjust the pH, and performing cooling to obtain the product. The synthesis method has the advantages of simplicity in operation, low cost of raw materials, mild reaction conditions, and green and environmentally-friendly process, so the method is very suitable for large-scale industrial production; and the solid polycarboxylic acid water reducer prepared by the synthesis method has excellent water-reducing and dispersing performances, so the solid polycarboxylic acid water reducer has a broad application prospect.

Description

technical field [0001] The invention belongs to the technical field of concrete admixtures, in particular to a synthesis method of a solid polycarboxylate water reducer. Background technique [0002] In recent years, polycarboxylate superplasticizer is one of the key foundations and driving forces for the progress of modern concrete technology. Existing polycarboxylate water reducers are mainly formed by free radical polymerization of unsaturated polyether monomers and carboxyl monomers in aqueous solution. [0003] However, most of the polycarboxylate superplasticizers currently on the market exist in liquid form, so they have a series of shortcomings such as high transportation costs and inconvenient storage, and cannot be used in special engineering fields such as dry powder mortar and grouting materials; while solid The emergence of (powder) polycarboxylate superplasticizer just made up for the above shortcomings. [0004] Solid polycarboxylate superplasticizers are ma...

AI Technical Summary

Problems solved by technology

For example, Chinese patent CN1919772 discloses a method for preparing a powder polycarboxylate water reducer, which is achieved by spraying the water reducer and drying it with hot air. As mentioned above, it is obvious that the production energy consumption of this method is too high

For example, Chinese patent applications CN106749967A and CN106749968A have reported adding an organic solvent of 20-50% by mass of a macromonomer to the polymerization system to synthesize an early-strength or slump-preserving water reducer; Solvent removal, which not only consumes a lot of energy, but also causes serious environmental pollution and treatment costs due to the use of a large amount of organic solvents

As another example, Chinese patent application CN106986970A discloses a method for preparing a high-performance solid polycarboxylate water reducer. In this method, electrolyte and 8-21% water are added to the polymerization system to reduce the viscosity. After the completion, further high-temperature and high-pressure dehydration operations are required, which shows that its energy consumption is still high, and the overall preparation process is complicated

[0006] In the prior art, the polyether macromonomer used to synthesize polycarboxylate water reducers is generally solid, and direct use in bulk polymerization will lead to excessive viscosity of the system and low conversion rate of polymerization reaction

In view of this, the existing technology mainly reduces the viscosity of the system by adding water or organic solvents, however, such operations will lead to higher energy costs

In addition, Chinese patent application CN108084362A discloses a solid polycarboxylate water reducer and its preparation method and application, wherein a liquid polyether macromonomer is used to synthesize a solid polycarboxylate water reducer, thereby reducing the viscosity of the system; However, the preparation of the liquid monomer itself is cumbersome and costly, and is not suitable for large-scale industrial production.

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