Preparation method of poly dimethyl allyl ammonium chloride

Abstract

The invention discloses a preparation method of polydimethyl diallyl ammonium chloride. It is based on the industrial cationic monomer DMDAAC aqueous solution obtained by a high-yield one-step clean preparation process as a raw material, adding persulfate as an initiator and Na4EDTA complexing agent at one time, controlling the reaction temperature under stirring, and controlling the initiation rate according to gradient temperature rise , initiate the polymerization reaction of monomer DMDAAC at a lower temperature, increase the degree of polymerization of the product PDMDAAC, improve the relative molecular weight, add an aqueous solution containing a small amount of initiator at a higher temperature in the later stage of the reaction to improve the monomer conversion rate in the product, and finally By controlling the amount of dilution water added, the solid content of the product is adjusted. The present invention is not only easy to obtain polymer products with higher relative molecular weight, but also has good economical and industrial bases for its preparation method; the initiation temperature is reduced, and the polymerization reaction is carried out under relatively mild conditions, which is easy to operate and low in production cost; PDMDAAC products with different solid contents and different uses can be obtained.

Description

technical field The invention belongs to the industrial preparation technology of cationic quaternary ammonium salt homopolymerization products, in particular to a preparation method of polydimethyl diallyl ammonium chloride. Background technique Poly-Dimethyldiallyl ammonium chloride (PDMDAAC for short) is a cationic quaternary ammonium salt monomer. The poly product, its molecular structure and polymerization reaction formula are as follows: In the formula, n, m=2, 3, 4, .... PDMDAAC is an aqueous linear polymer with cationic quaternary ammonium salt groups, and it is also a cationic polyelectrolyte. PDMDAAC is white water-absorbing powder, soluble in water, methanol and glacial acetic acid, insoluble in other solvents. The product is generally an aqueous solution, but there are also dry powder products. At room temperature, the aqueous solution of PDMDAAC is stable in the range of pH 0.5-14. Because of its non-toxicity, good water solubility, high positive charge...

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Problems solved by technology

(1) Documents 1, 2, 3, 5, and 6 cannot explain the process of preparing the cationic monomer DMDAAC used, so that the economics of the resulting PDMDAAC preparation process cannot be evaluated

(2) Documents 1, 2, 5, 6, 7, and 9 have adopted azo initiators or composite initiators thereof with low degree of industrialization and commercialization, thereby affecting the production cost of its product PDMDAAC and the industrial application of production technology

Documents 8 and 10 use one-step monomer as the raw material, and the process conditions are mild, but the relative molecular weight of the product is low, which does not exceed 1.35dL / g

(4) Documents 7 and 9 obtain the characteristic viscosity of the refined product after the small molecule product of the unreacted monomer is washed away, so its preparation method is only applicable to laboratory research work

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