| 摘要 |
This invention relates to the suspension polymerization of vinyl halides and vinylidene halides in an aqueous medium to make polymers and copolymers which are designed for use in making plastisols. The process is conducted in an aqueous medium using a free-radical yielding catalyst, and in the presence of a hydrolyzed polyvinyl acetate (polyvinyl alcohol) having a degree of hydrolysis in the range of about 65% to about 85% and a compound having a hydrophile-lipophile balance (HLB) less than about 3.5. The important aspect of the present new process is the use of agitation ramping, that is, changing the degree of agitation during the course of the reaction, and adding the catalyst to the reaction medium after the same has reached the reaction temperature whereby these are produced polymer particles which are dense spherical glassy beads having an average diameter in the range of about 10 to about 100 microns. The suspension resins so produced are easily and uniformly mixed with a plasticizer to form plastisols which are stable, containing particles of uniform and proper size, and capable of producing films, and like products, of good clarity.
|
