| 摘要 |
<p>1,186,565. Fractionating alpha-olefin polymers. SUN OIL CO. 12 June, 1967 [17 June, 1966], No. 26969/67. Heading C3P. Substantially pure amorphous alpha-olefin polymers are recovered from a saturated hydrocarbon solution containing 0À1 to 10 per cent by weight of a mixture of amorphous, stereoblock and crystalline alpha-olefin polymers by (a) heating and concentrating the dilute polymersolvent solution by distilling off solvent to a concentration of from 10 to 40 weight per cent polymer in solution, (b) cooling the concentrated solution to a temperature of from 15‹ to 30‹ C., (c) centrifuging the cooled solution and recovering a filtrate substantially free of crystalline polymer, (d) diluting the centrifuged filtrate with hydrocarbon solvent to a polymer in solvent concentration of from 5 to 15 weight per cent polymer, (e) filtering the resulting diluted centrifuge filtrate and recovering an amorphous alpha-olefin polymer solution substantially free of stereoblock polymer and (f) recovering from the last-mentioned solution a substantially pure amorphous alpha-polymer. The above starting solution is obtained from a polymerization process using a Ziegler-Natta-type catalyst after the polymerizate has been treated to recover from it the hexane insoluble fraction i.e. the crystalline or isotactic fraction. The preferred polymers are polypropylene and copolymers of ethylene and propylene. A flow diagram is given of a continuous method for recovering substantially pure amorphous alphaolefin polymers.</p> |
