| 摘要 |
<p>Prepn. of polyolefins comprises polymerisation of ethylene opt. together with an alpha-olefin CH2=CH4 (in which R is 1-6C alkyl), and a linear or cyclic diene or polyene ter-monomer, in presence of a catalysts system of (1) an organic Al cpd., (2) a 3-5 valent V cpd. soluble in inert organic solvent, and (3) an activator consisting of either (A) an ester of formula CX3COOR' (in which R' is a linear or cyclic gp with an ether bond, and X is halogen), or (B) a reaction product of PCl5 with a alcohol. Pref. (1) is of formula R"nAlX3-n, (in which R" is an 1-20C hydrocarbon gp.; X is halogen; n is 1-3). (2) is a V halide, oxyhalide, complex with O-contg. cpd. or a vanadyl ester. Used for prodn. of thermoplastics and synthetic rubbers of known types. Addn. of activator (3) to the Ziegler catalyst system gives increased activity which is maintained over longer reaction times, and allows use of much less V cpd. (2). No gel formation occurs when a polyene termonomer is used, in contrast to known activators such as alkyl esters of trichloro-or tribomo-acetic acid.</p> |
