| 摘要 |
<p>1531544 Polymerization of ethylene UNION CARBIDE CORP 27 Feb 1976 [10 March 1975 14 Jan 1976] 7852/76 Heading C3P Solid copolymers of ethylene having a density of 0À90 to 0À941 gm./c.c. and a melt index greater than zero and less than 2 are prepared by copolymerizing ethylene with a C 3 -C 6 alpha olefine in an amount to provide 1 to 15% of the alpha olefine in the polymer at a pressure of less than 1000 p.s.i.g. in a fluidized bed of particles of a thermally activated supported catalyst having a particle size of 50 to 200 microns and containing 0À05 to 3% by weight of Cr, at least part of which is in the hexavalent state, 1À5 to 9À0% by weight of Ti and 0À0 to 2À5% by weight of F, at least a portion of both the Cr and the Ti being in the form of oxides. The support may be, e.g., silica, alumina, zirconia or thoria. The olefin may be propylene, butene-1, pentene-1 or hexene-1. In the examples ethylene is copolymerized with butene-1 in the presence or absence of hydrogen in a fluidized bed of a catalyst prepared by reacting silica with an aqueous solution of CrO 3 , subsequently with tetraisopropyltitanate and then in some cases with (NH 4 ) 2 SiF 6 , followed by thermal activation. Reference has been directed by the Comptroller to Specification 1,429,174.</p> |
