| abstract |
A method for producing crystalline copolymers of propylene (major component), ethylene and an alpha -olefin having 4 to 12 carbon atoms, superior in any of various practical physical properties such as cold-resistance, transparency, heat-seal temperature, percentage shrinkage, etc. is provided, wherein a catalyst solution obtained by mixing together a titanium trichloride composition (obtained by mixing and milling a titanium trichloride with a mixed reaction product of TiCl4 with an ether), a dialkylaluminum halide, an electron-donor compound and an inert solvent, is activated in advance of copolymerization, by feeding propylene into the solution under specified feeding conditions, and copolymerization is carried out by feeding propylene and said alpha -olefin simultaneously and continuously, while feeding ethylene intermittently into the gas phase part of the polymerization zone containing the solution. |