Modified melamine water reducer and preparation method thereof

Abstract

The invention relates to the field of concrete admixture and discloses a modified melamine water reducer and a preparation method thereof. An organic long chain is introduced to a molecular terminal position of the modified melamine water reducer, the mole ratio of a long-chain raw material to formaldehyde is 1:1 during synthesis of the organic long chain, and the mole ratio of melamine to formaldehyde to sodium hydrogen sulfite to a terminal-group long chain is 1: (3.5-3.8): (1.5-2.0): (0.03-0.05). The invention further discloses the preparation method of the modified melamine water reducer. The preparation method comprises steps as follows: synthesizing the terminal-group long chain; adding formaldehyde and sodium hydrogen sulfite for hydroxymethylation and sulfonation reactions of melamine; performing a condensation polymerization reaction under the acidic condition; adding alkali for reforming and weak bond fission of polymer molecules, and removing formaldehyde residues. A water reducer molecule main chain is introduced to a terminal position of the long chain through a condensation reaction of hydroxyl groups in a solution, space steric hindrance is added to a dispersion system, the repulsive interaction among cement particles is further improved, and the water reducing effect is further improved.

Description

technical field [0001] The invention relates to the field of concrete admixtures, in particular to a modified melamine water reducer and a preparation method thereof. Background technique [0002] Water reducer is a concrete admixture that can reduce the amount of mixing water while maintaining the slump of concrete. Most of them are anionic surfactants, such as lignosulfonate, naphthalenesulfonate formaldehyde polymer, etc. After being added to the concrete mixture, it can disperse the cement particles, improve its workability, reduce the unit water consumption, increase the concrete strength and improve the durability; or reduce the unit cement consumption and save cement. [0003] According to chemical composition, water reducers are usually classified as follows: lignin sulfonate water reducer, naphthalene-based high-efficiency water-reducer, melamine-based high-efficiency water-reducer, sulfamate-based high-efficiency water reducer , Fatty acid-based superplasticizers...

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Problems solved by technology

[0008] The technical problem to be solved by the present invention is that, in view of the defects in the prior art such as the large slump loss of the melamine-based water-reducer and serious environmental pollution caused by the volatilization of formaldehyde during the preparation process, the present invention provides a modified melamine-based water-reducer and its preparation method, through a method of polymerizing long chains at the end group that is relatively easy to achieve in the solution synthesis process, through the condensation reaction between hydroxyl groups, the organic long chain is introduced into the molecular main chain of the melamine water reducer at the end position, in order to Realize the increase of steric hindrance in the dispersion system, and further improve the repulsion between cement particles, so as to significantly improve the water reducing effect

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