Hyper-branched polycarboxylate high-efficiency water reducing agent and preparation method thereof

Abstract

The invention relates to a hyper-branched polycarboxylate high-efficiency water reducing agent and a preparation method thereof. The water reducing agent is prepared by polymerizing one of tert-butyl acrylate and methyl tert-butyl acrylate with sodium methyl-acryl sulfonate and allyl polyethenoxy ether to form a copolymer main chain, and then performing condensation polymerization on one of acrylic acid and methacrylic acid with ethylene diamine to form a hyper-branched polyamide structure which is grafted to two ends of the main chain. The preparation method comprises the following steps: (1) preparing the sodium methyl-acryl sulfonate into solution with DMF, and heating the solution in a nitrogen atmosphere; (2) dissolving the other two monomers and an initiating agent into the DMF to prepare mixed solution, and dripping the mixed solution into the step (1) to react for 1 to 20 hours; (3) adding a condensating agent CDI after the reaction and performing condensation reaction by using N-methyl morpholine as an organic base, the ethylene diamine and the acrylic acid as the monomers and the DMF as a solvent; and (4) performing vacuum distillation to remove the residual monomers and the solvent, and refluxing for 2 to 5 hours by using methylene chloride solution of trifluoroacetic acid to obtain the water reducing agent. The hyper-branched polycarboxylate water reducing agent has the advantages of low admixture, high water reducing rate, small slump loss, good compatibility with cement, no corrosivity to steel bars, strong frost resistance and the like.

Description

technical field [0001] The invention relates to a hyperbranched polycarboxylate high-efficiency water reducer and a preparation method thereof, belonging to the technical field of concrete admixtures in chemical building materials. Background technique [0002] At present, the requirements for high-performance concrete are not only high strength, but more attention is paid to the long-term and ultra-long-term durability of this structural material, as well as compactness, stability and excellent construction performance on the basis of high strength. In the technical measures for preparing high-performance concrete, in addition to the high requirements for cement and aggregate, the most important feature is the use of ultra-fine powder admixtures (ground slag, silica fume, powder coal ash, etc.) and chemical admixtures, especially high-performance water-reducing agents with high-efficiency water reduction, proper air-entrainment and reduced slump loss over time. The high-ef...

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Problems solved by technology

[0003] Polycarboxylate concrete high-performance water reducer is a research hotspot in various countries in the world in recent years. The earliest polycarboxylate high-efficiency water reducer is mainly composed of copolymers of olefins and unsaturated carboxylic acids. Later, external improvement and copolymerization technology There are many breakthrough improvements on the market, but the polycarboxylate superplasticizers in our market generally have problems such as poor adaptability to various cements and unstable product performance. Modification is imperative

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