A kind of preparation method of polycarboxylate superplasticizer containing phosphonic acid group

Abstract

The invention provides a preparation method of a polycarboxylic acid water reducing agent containing a phosphate group. The preparation method comprises the following steps: firstly, preparing a terminal alkenyl unsaturated phosphonic acid monomer; secondly, mixing acrylic acid, the unsaturated phosphonic acid monomer, a chain transferring agent and de-ionized water to prepare a mixed monomer solution; by taking an alkenyl polyoxyethylene ether macro-monomer solution as a base material, dropwise adding an initiator water solution and the mixed monomer solution respectively under a room-temperature polymerization condition; uniformly stirring, dropwise adding and reacting; and finally neutralizing with a sodium hydroxide solution to obtain the polycarboxylic acid water reducing agent. According to the water reducing agent, the terminal alkenyl unsaturated phosphonic acid monomer is introduced into a structure and primary adsorption is facilitated; the initial dispersity is improved, and hydration and agglomeration of cement are delayed; the slump retaining property is effectively improved and the sensitivity to concrete is reduced; and the stress resistance and adaptability on different aggregate are enhanced.

Description

technical field [0001] The present invention relates to a preparation method of polycarboxylate water-reducer containing phosphonic acid groups, especially the polycarboxylate water-reducer which introduces terminal ethylenically unsaturated phosphonic acid as polymerized monomer into the structure of traditional water reducer Preparation. Background of the invention [0002] Under the condition of low water-cement ratio and low dosage, polycarboxylate superplasticizer has the outstanding advantages of high pulp fluidity, small slump loss, and environmental protection. Due to the gradual deterioration of sand and gravel resources all over the country during the mixing process of concrete, polycarboxylate superplasticizers are very sensitive to the minerals in clay compared to cement. Therefore, polycarboxylate superplasticizers have a strong tendency to adsorb clay, which has a great impact on the transportation, retention and strength of concrete during construction. At t...

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Problems solved by technology

[0003] The publication number is CN 105236806 A, which discloses a "highly adaptable phosphoric acid-modified polycarboxylate water reducer and its preparation method". The invention first utilizes 2-phosphoryl-1, 2, 4-tricarboxylic acid Butane, p-toluenesulfonic acid, hydroquinone and allyl alcohol are used as raw materials to synthesize unsaturated phosphoric acid-based monomers, and then modified to obtain polycarboxylate water reducers, which have good resistance to sulfate ions and mud resistance. However, there are many raw materials for the preparation of unsaturated phosphoric acid-based monomers, the process is complicated, and the monomer yield cannot be effectively guaranteed.

[0004] The publication number is CN 105418857 A, which discloses "the preparation method and application of polycarboxylate water reducer containing phosphate groups". In this invention, the polycarboxylate water reducer prepolymer is firstly prepared, and then the The prepolymer is esterified with a phosphoric acid esterification reagent to obtain a phosphorylated modified polycarboxylate water-reducer. The water-reducer described in this invention has good alkaline water performance and good slump retention ability, but this invention is not available in organic If it is carried out in a solvent, subsequent treatment of the polycarboxylic acid product is required, and the esterification rate in the phosphorylation modification cannot be effectively guaranteed

[0005] The publication number is CN 105566572 A, which discloses "a maleic anhydride grafted polycarboxylic acid plasticizer and its preparation method". The invention utilizes maleic anhydride, cellulose hydroxypropyl methyl ether and phosphorous acid as raw materials. The intermediate polyester is synthesized, and then polymerized to obtain a polycarboxylate water reducer, which has a comprehensive effect of good dispersibility, plastic retention and thickening, but the preparation process of the reaction intermediate polyester is complicated, and the molecular weight control is difficult. low rate

[0006] There is also a publication number of CN 103848944 A which discloses "a method for preparing a super retarded polycarboxylate water reducer"; a publication number of VN 104059199 A which discloses "a polycarboxylic acid super retarded water reducer and its Preparation method and application”; Publication No. VN 102503217 A discloses: “A high-slump-retaining polycarboxylate-based high-performance water reducer and its preparation method”, etc., all of which improve the dispersion and slump-retaining properties of concrete , but most of them are limited by the complex preparation method and high cost, so they are not suitable for industrial production

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