| 摘要 |
<p>1422827 Production of foamable vinylidene chloride/acrylonitrile copolymers DOW CHEMICAL CO 9 July 1973 [10 July 1972] 32592/73 Heading C3P Microspheres comprising a blowing agent encapsulated by a polymer are produced by a process which comprises polymerizing 60-90 parts by wt. of vinylidene chloride and 40-10 parts by wt. of acrylonitrile mixed with a liquid volatile blowing agent, all dispersed as an oil in water emulsion with a dispersion stabilizer, as droplets of diameter 1-50 microns, to form particles comprising said encapsulated blowing agent, characterized in that 3-12 parts by wt. of a further monomer is present, having a propagation constant of 2-15,000 litres/mole/see. and where r 1 is the reactivity ratio for the further comonomer and r 2 is the reactivity ratio for acrylonitrile, with the further proviso that the vinylidene chloride/acrylonitrile/blowing agent are mutually soluble at between 20 and 90‹ C. The further monomer may be selected from methacrylonitrile, 1 - acetoxy - 1,3 - butadiene, acetoxy styrene, acrolein, acrylamide, acrylic acid, allyl alcohol, butadiene methacrolein, or mixtures thereof. Suitable blowing agents are butane, isobutane, neopentane and mixtures thereof.</p> |
