A kind of viscosity reducing type polycarboxylate water reducer and preparation method thereof

Abstract

The invention discloses a viscosity-reducing polycarboxylate water reducer and a preparation method thereof. Its pH is 6-7, and its solid content is 48-52%. Stepwise polymerization based on activity difference: first monomer, maleic anhydride, vinyl acetate, second monomer, oxidizing agent, reducing agent, chain transfer agent, water and appropriate amount of sodium hydroxide solution. The viscosity-reducing polycarboxylate water-reducer of the present invention uses monomer activity and free radical activity difference to polymerize step by step, introduces maleic anhydride-vinyl acetate alternating copolymer, and forms a layer of protective film on the surface of the adsorbed droplet to prevent colloid Agglomeration, while reducing surface tension, improving dispersion performance, and reducing the viscosity of concrete; at the same time taking into account the performance of slump retention and water reduction, the process is simple, the raw materials are easy to purchase without customization, the cost is low, and it is easy to industrialize.

Description

technical field [0001] The invention belongs to the technical field of building admixtures, and in particular relates to a viscosity-reducing polycarboxylate water reducer and a preparation method thereof. Background technique [0002] With the rapid development of my country's construction industry, especially the planning and implementation of the national railway passenger dedicated line network project, the market demand for polycarboxylate water reducers continues to grow. High-grade concrete is being more and more used in engineering construction because of its high overall strength and light weight. Due to the development of concrete in the direction of high strength, high durability, self-leveling and other high performance, with the application of large-volume mineral admixture technology and the reduction of concrete water-binder ratio, the viscosity of concrete increases, which increases the difficulty of concrete construction. Polycarboxylate water reducer has a...

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Problems solved by technology

[0003] CN105732911A discloses a preparation method and application of a viscosity-reducing polycarboxylate water reducer. The invention is composed of a specific unsaturated acid monomer, a specific unsaturated polyether macromonomer and N-(4-vinylbenzyl radical)-N,N-dialkylamines in molar ratio (2.5~6.5):1:1:(0.05~0.2) to carry out free radical copolymerization to obtain viscosity-reducing polycarboxylate superplasticizer, the raw material of this method needs specific Polyether monomer needs to be customized, and the effect of reducing viscosity has not been explained

[0005] CN106008784A discloses a concrete viscosity reducer and its preparation method. It is formed by polymerizing 4-hydroxybutyl vinyl ether, unsaturated amide and unsaturated phosphoric acid ester as raw materials. Although the concrete viscosity reducer prepared by the invention has a simple production process , can effectively solve the problem of high viscosity and poor workability of concrete, but because the synthesized viscosity reducer has a small molecular weight, electrostatic repulsion and steric hindrance effect, its water reducing rate is correspondingly low, and it is difficult to meet the requirements of high-grade concrete for water reduction at the same time. The demand of water agent in terms of water reducing rate and viscosity reducing

However, the unsaturated modified polyoxyethylene ether macromonomer used in the synthesis process of the water reducer is formed by random copolymerization of ethylene oxide and propylene oxide, and has a relatively large molecular weight, which is very important for adjusting the hydrophilicity and hydrophobicity of the molecular structure and reducing viscosity. It is difficult to make a large contribution to the effect

At the same time, the preparation method of the two-step process and compounding is relatively complicated, and the subsequent industrialization and economics are still problems.

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