Process for producing polybutene-1

A process for producing polybutene-1 which comprises polymerizing butene-1 in the presence of a catalytic amount of a catalyst system comprising a solid catalytic component (A) obtained by reacting a reaction product (a) of a Grignard reagent with a chain or cyclic hydropolysiloxane having the unit ##EQU4## (R.sup.1 represents an alkyl, aryl, aralkyl, alkoxy or aryloxy group;

• a is 0, 1 or 2;
• b is 1, 2 or 3 and a+b.ltoreq.3) with at least one compound having the formula
• R.sup.2.sub.n M.sup.(z) X.sub.z-n
• (R.sup.2 represents a C.sub.1 to C.sub.12 hydrocarbon moiety;
• M represents Al or Si;
• z represents atomic value of 3 or 4;
• X represents a halogen atom;
• n is 0, 1 . . . (z-1)) to obtain a reaction product (b) and further reacting said reaction product (b) with at least one titanium halide in the presence of an organic acid ester to produce said solid catalytic component (A), and further comprising a trialkylaluminum compound (B), an organic acid ester (C);
• and an organoaluminum compound (D) having the formula
• AlR.sup.3.sub.2 Cl
• (R.sup.3 represents a C.sub.1 to C.sub.8 hydrocarbon moiety), at a molar ratio of said organoaluminum compound (D) to said trialkylaluminum compound (B) ranging from 0.1 to 10.