| 摘要 |
A two-stage rate controlling process for polymerizing vinyl fluoride comprises nucleating polyvinyl fluoride particles in a first reaction zone and then polymerizing the bulk of the vinyl fluoride in a second reaction zone, the nucleation being carried out for a time such that the rate at which polymer is formed in the second zone is independent of the rate of nucleation. Preferably 25 to 50% of the total of each of a water-soluble initiator stream, a water stream and a vinyl fluoride stream are continuously passed into the first reaction zone, in which polyvinyl fluoride particles are continuously nucleated until no more than 1% total solids are formed, the nucleated polyvinyl fluoride stream is removed therefrom and combined with the remainder of the initiator stream, water stream and vinyl fluoride stream and the combined stream is passed into the second reaction zone. The temperature and pressure in the second reaction zone are higher than those in the first reaction zone. Conventional free-radical catalysts are used. |
