Dispersant and preparation method thereof, and application of dispersant in anionic polyacrylamide water-dispersible emulsion polymerization

Abstract

The invention provides a comb-type graft copolymer dispersant and a preparation method thereof, and an application method of the dispersant in anionic polyacrylamide emulsion polymerization. Three monomers are subjected to free radical addition copolymerization reaction to obtain the comb-type graft copolymer. The dispersant provided by the invention has the advantages of low molecular weight, low negative charge density, strong side-chain steric hindrance, low viscosity, high dissolving speed, low brine sensitivity, quick diffusion and adsorption, high stabilization efficiency and adjustable molecular structure, effectively lowers the viscosity of the emulsion polymerization system, and enhances the solid content of the product and the stability of the water-dispersible emulsion.

Description

technical field [0001] The invention belongs to the technical field of water-soluble polymer synthesis, and in particular relates to a dispersant, a preparation method thereof, and a polymerization method of an anionic polyacrylamide water-dispersed emulsion. Background technique [0002] The structural characteristics and complete varieties of polyacrylamide make it widely used in various fields of the national economy, and enjoys the title of "auxiliary for all industries". In my country, the application of polyacrylamide in the three major fields of petroleum, water treatment and papermaking is particularly important. [0003] The methods of synthesizing polyacrylamide include solution polymerization, inverse suspension polymerization and inverse emulsion polymerization. In the late stage of solution polymerization, the viscosity is very high, stirring and heat dissipation are very difficult, and special equipment is required to dry and make powder. The complicated proce...

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Problems solved by technology

[0005] Compared with the cationic type, the synthesis of anionic polyacrylamide in saline medium is much more difficult because it is difficult to select acrylamide derivative monomers with hydrophobic groups for copolymerization, and related researches are still relatively rare.

CN101649024A promotes precipitation and phase separation by adding acrylate hydrophobic monomers, and at the same time adds functional monomers with surface activity to improve the early stabilization efficiency, but the introduction of such hydrophobic monomers often reduces the molecular weight of the product, while the solubility is greatly improved become worse; CN1519259A improves the stabilizing effect by adopting a composite stabilizer of non-ionic macromolecule and polyol compound, but polyol compound has a chain transfer effect on free radical polymerization, which is unfavorable for obtaining high molecular weight products

[0006] It can be seen that the choice of dispersant has an important impact on the reaction. The current patents and literatures use linear anionic polymers or non-ionic polymers as dispersants, and stabilize the latex particles by utilizing the steric hindrance generated by the polymer adsorption on the particle surface. , which requires the dispersant to have a certain molecular weight (up to 500,000 to 1.5 million), which brings a series of problems: first, the reaction is carried out in a high-salt medium, and the dispersant with too high molecular weight is difficult to dissolve quickly. , its molecular conformation is in a curled state affected by the salt concentration, which greatly reduces its adsorption rate and stabilization effect; secondly, the high molecular weight of the dispersant causes a relatively high viscosity in the initial stage of the reaction, coupled with the entanglement between polymer chains, and The polymer chain is difficult to diffuse and move, and the adsorption rate of the dispersant is very slow at the initial stage of the reaction. Often, the viscosity of the system increases sharply due to the inability to stabilize the precipitated latex particles in time, resulting in polymerization failure.

Thirdly, the charge density of the linear anionic polymer is relatively high, and it has a strong charge repulsion with latex ions, which easily causes the desorption of dispersant molecules on the surface of latex particles, which is not conducive to the long-term storage stability of water-dispersed emulsions.

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