| 摘要 |
A process for preparing, in aqueous emulsion, controlled interpolymer compositions. The interpolymer compositions have polymerized therein from about 86 to 92 mole percent, vinylidene chloride, from about 14 to 8 mole percent of a comonomer mixture of methyl methacrylate and a comonomer selected from the group consisting of acrylonitrile, methacrylic acid and methacrylonitrile in a ratio of the comonomer to methyl methacrylate of from about 0.5:1 to 2:1, and from about 0.5 to 1.0 weight percent itaconic acid, based on weight of vinylidene chloride plus comonomer mixture. The interpolymers are prepared in a three step process. The third step, or Step III, wherein monomer feeding is step-wise reduced for a portion of the step and a polymerization initiator is added at generally the same constant rate as the rate of addition in Steps I and II, generally reduces the amount of unreacted mixed monomers remaining after monomer addition is completed. As such, the detrimental results produced when a large amount of polymer composition variation in the direction of high vinylidene chloride fractions are markedly reduced.
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