Process for producing propylene copolymer

Claim 1

In a process for producing propylene copolymer containing about 85 to 97.5 mol % propylene and about 2.5 to 15 mol % ethylene and/or an α-olefin having 4-18 carbon atoms using a Ziegler-Natta catalyst, the improvement which comprises said Ziegler-Natta catalyst comprising: [A] titanium trichloride prepared by reducing titanium tetrachloride with an organoaluminum compound represented by the formula: AlR.sub.l X.sub.3-l wherein R represents a straight chain, branched chain or cyclic alkyl group or aryl group having up to 18 carbon atoms and X represents a halogen atom or a hydrogen atom and l is a number 1≦l≦3, and reacting the reduced solid with an ether and a halogen compound simultaneously or successively, wherein said ether is an ether represented by the formula: R.sup.1 --O--R.sup.2 wherein R 1 and R 2 are each a straight chain, branched chain or cyclid alkyl group having 1 to 10 carbon atoms, and said halogen compound is selected from the group consisting of (i) halogen or interhalogen compounds of the formula: X.sup.1 X.sup.2 a wherein X 1 and X 2 are each a chlorine, bromine or iodine atom and a is a number from 1 to 3; (ii) titanium halides; and (iii) organic halogen compounds, and [B] an organoaluminum compound represented by the formula: AlR.sup.4.sub.3-m X.sup.4.sub.m wherein R 4 is an alkyl group having 1 to 18 carbon atoms, X 4 is a hydrogen, chlorine, bromine or iodine atom or an alkoxy group having 1 to 8 carbon atoms and m is a number satisfying the relation 0≦m≦3: with the molar ratio of [B]/[A] being about 30 to 70.