PvP is the monomer vinyl Pyrrolidone (NVP) as raw material, through the bulk polymerization, solution polymerization and so on. In the process of bulk polymerization, because of the large viscosity of the reaction system, polymer is not easy to diffuse, polymerization reaction heat is not easy to remove the local overheating and other problems, so the product has low molecular weight, residual monomer content is high, and more yellow, not too much practical value. PvP is generally synthesized by solution polymerization in industry.
PvP production polymerization has two main routes, the first being the Cyanoethyl pyrrolidone (NVP) in the organic solvents for solution polymerization, and then steam stripping. The second route is the aqueous solution polymerization of nvp monomer and water-soluble cation, anion or nonionic monomer.
The NVP monomer is heated directly to more than 140 Shan, or the initiator is heated in a NVP solution, or in a NVP solution (the solvent can be water, ethanol, benzene, etc.) to add initiator through free radical solution polymerization, or direct light irradiation NVP monomer or its solution can obtain the PVP aggregates, the polymerization method is different, the polymer structure and the performance are different, in which the free radical solution polymerization obtains the polymer composition, the structure is homogeneous. The performance is also relatively stable, is the most commonly used method of NVP polymerization, adjust the monomer concentration, aggregation temperature, initiator dosage and other reaction conditions that can be different molecular weight and different water-soluble pvp aggregates.
Process one: The NVP is configured into a solution with a mass fraction of 50%, with a small amount of hydrogen peroxide as a catalyst, under the action of Azo-Butadiene nitrile, under 50 Shan polymerization, so that nvp almost all into PvP. Adding ammonia to the polymer to decompose the residual azo-butadiene nitrile, the monomer polymerization conversion rate was nearly 100% and the solid content was 50%.
Process two: Add 0.4 G dispersant P (NVP-Co-vac) and $number g disperse medium acetic ester in $number ml four-port flask, 70 Shan constant temperature water bath after mixing dissolve, add nvp and 0. G Initiator aibn, nitrogen atmosphere reaction 6 h, cooling and filtration, insoluble in vacuum drying box in the vacuum drying 24h, white pvp solid powder.
The vast majority of PvP polymers use aibn as initiators, and there is no literature on the initiation of synthetic PvP by a water-soluble azo-like initiator, but someone is doing this work. Since NVP monomer and PvP are soluble in water, it is possible to use water-soluble azo initiator to induce polymerization to produce linear PVP polymers, moreover, AIBN contains a group of harmful groups of cyanide, and water-soluble azo-like initiators mostly do not contain cyanide, PvP is mostly used in direct contact with the human product, so water-soluble azo initiator than aibn more advantages.