ORGANOALUMINOXY PRODUCT, PREPARATION PROCESS, USE IN CATALYST SYSTEM AND POLYMERIZATION PROCESS

The prepn. of a solid organoaluminoxy prod. useful as a polymerisation. cocatalyst comprises contacting (a) an organoaluminoxane of formula R[Al(R)-O]n-AlR (I) or (II) and (b) an O-contg. cpd. selected from an organic peroxide of formula R2OOR3 (III), alkylene oxide of formula (IV) or (V), and organic carbonate of formula (VI) or (VII), the molar ratio of organoaluminoxane : O-contg. cpd. being 1:1 - 1000:1. R = 1-8C hydrocarbyl, n = 2-50, and m - 3-50. R2OOR3 (III). R2 and R3 = H, hydrocarbyl, and hydrocarbonyl selected from 1-24C alkyl, cycloalkyl, aryl, alkenyl, and alkynyl, provided that at least one of R2 or R3 is a hydrocarbyl or hydrocarbonyl radical. R4 and R5 = H and 1-12C alkyl. R6 and R7 = H and 1-10C alkyl; and R8 = 1-12C alkyl, cycloalkyl, aryl, aralkyl and alkaryl. Also claimed are (i) a solid organoaluminoxy prod. prepd. by the above process; and (ii) an olefin polymerisation. catalyst system comprising the above solid organoaluminoxy prod. and at least one transition metal contg. olefin polymns. catalyst of formula(R8O)2C(O) (VIII). MLx (VIII). M = gp. IVB or VB transition metal; x = valence of the transition metal; and L = 5-20C cyclopentadienyl-type radicals, 1-12C hydrocarbyl radicals, 1-12C alkoxy radicals, 6-12C aryloxy radicals, halogen and H.