Preparation method of polyvinylamine

Abstract

The invention discloses a preparation method of polyvinylamine. In the method, degradation reactions including chlorination, a rearrangement reaction, separation and purification are undergone on polyacrylamide serving as a raw material. In the chlorination, a nonionic surfactant is added into a mixed solution of sodium hydroxide and sodium hypochlorite, polyacrylamide serving as the raw material is added in batches at the temperature between 10 DEG C below zero and 0 DEG C for reacting for 1 hour by stirring, and the dosage of the surfactant is 3-5 percent by weight of the weight of the raw material. In the rearrangement reaction, chlorination mixed liquor is slowly added into a sodium hydroxide solution with the concentration of 20-50 percent by mass at the temperature between 10 DEG C below zero and 0 DEG C at the speed between 15 millimeters per minute and 35 millimeters per minute for reacting for 5-8 hours by stirring, and at least 5 times of excessive alkali liquor is used according to the mass of polyvinylamine serving as the raw material. By adopting the nonionic surfactant in the method, the surface tension of the solution is lowered, stretching of a main chain is promoted, an amido group is fully shown and is fully chlorinated in time, and hydrolysis is reduced. Meanwhile, an alkali-containing mother liquor can be recovered and reused.

Description

1. Technical field [0001] The invention relates to a preparation method of polyvinylamine. 2. Background technology [0002] Polyvinylamine (PVAm) is a chain-like, multi-amino water-soluble new polymer material. Because the side functional amino group is very active, PVAm can perform most of the characteristic reactions of amino groups, thereby obtaining many special new functions. PVAm and its derivatives are used as flocculants, water-retaining agents, sizing agents, and reinforcing agents in papermaking in industries such as textiles, medicine, petroleum extraction and processing, and construction. At present, the synthesis methods of polyvinylamine mainly include Hofmann degradation method, poly N-vinyl formylated polymer hydrolysis method, and polyvinyl chloride digestion method. [0003] Hofmann downgrading polyacrylamide is the main method reported at present to synthesize PVAm, that is, in sodium hypohalite and sodium hydroxide aqueous solution, polyacrylamide under...

AI Technical Summary

Problems solved by technology

[0007] The first is that this method generally uses water or methanol as a solvent, and the polyacrylamide input has a small molecular weight and a mass fraction of about 5%, and the reactant concentration is low, resulting in low industrial production capacity.

The second is the intermediate product of isocyanate generated during the Hofmann reaction, which will condense with amino and amide groups to form acyl uric by-products, which will reduce the yield of polyvinylamine products and affect product quality.

Fourth, post-treatment after the Hofmann rearrangement reaction needs to consume a large amount of lye, which not only wastes but also increases the cost of wastewater treatment

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