Abstract: A highly crystalline polypropylene is provided having:(A) (i) a melt flow rate (MFR) in the range of 0.1-200 g/10 minutes 230.degree. C. and (ii) an absorbance ratio determined by infrared absorption spectroscopy, IR-.rho., of wave-number 997 cm.sup.-1, A.sub.997, to wave-number 973 cm.sup.-1, A.sub.973, which satisfies the equation:IR-.tau..gtoreq.0.0203 log MFR+0.950; and(B) (i) an IR-.tau. value of at least 0.97 of a component deposited initially in an amount of 2 to 3% by weight from a dilute, slowly cooled and stirred xylene solution of the polypropylene and (ii) a ratio of the weight average molecular weight of the deposited component (M.sub.w1) to that of the polypropylene (M.sub.w0), M.sub.w1 /M.sub.w0, of at least 3.

Abstract: A preactivated catalyst for producing .alpha.-olefin polymers is provided, which is obtained by the steps which comprises:reacting an organoaluminum compound (O-Al.sub.1) with an electron donor (ED.sub.1) to obtain a reaction product (I);reacting (I) with TiCl.sub.4 to obtain a solid product (II);reacting (II) with an electron donor (ED.sub.2) and an electron acceptor to obtain a solid product (III);combining (III) with an organoaluminum compound (O-Al.sub.2) and a reaction product (RP) of an organoaluminum (O-Al.sub.3) with an electron donor (ED.sub.3) (III), (O-Al.sub.2) and (PP) being referred to as catalyst components), and in this combination, subjecting a part or the whole of the catalyst components to polymerization treatment with an .alpha.-olefin at least in the presence of (III) and said (O-Al.sub.2) to obtain a preliminarily activated catalyst; andpolymerizing an .alpha.-olefin in the presence of the catalyst.

Abstract: A process for producing terpolymers of propylene (as a main monomer), ethylene and another .alpha.-olefin having superior and well-balanced physical properties, almost without forming soluble polymer is provided.This process is characterized by preliminarily activating a catalyst consisting of a titanium trichloride composition and a specified organoaluminum halide, with a small amount of an .alpha.-olefin of 2 to 12 carbon atoms, a trialkylaluminum and an aromatic ester, and copolymerizing specified amounts of propylene, ethylene and an .alpha.-olefin of 4 to 12 carbon atoms in the presence of the preliminarily activated catalyst obtained above.

Abstract: A process for producing .alpha.-olefin polymers with a controlled stereoregularity and with a higher yield is provided, which process comprises: combining a TiCl.sub.3 -containing composition obtained by reducing TiCl.sub.4, with an organoaluminum compound; thereafter subjecting the composition to a polymerization treatment with an .alpha.-olefin; before, during or after the polymerization treatment, adding an electron donor or/and an electron acceptor or a reaction product of these two; as well as adding a reaction product of a trialkylaluminum with an electron donor having a specified molar ratio of the electron donor to the trialkylaluminum selected in the range of 0.01 to 5; and polymerizing an .alpha.-olefin in the presence of the resulting preactivated catalyst.

Abstract: A process for producing .alpha.-olefin polymers is provided, which comprises: reacting an organoaluminum compound with an electron donor in a specified ratio in a solvent at a specified temperature to obtain a solid product (I); reacting solid product (I) with TiCl.sub.4 at a specified temperature in a specified ratio of Al/Ti and then removing a liquid portion from the resulting material followed by washing to obtain a solid product (II) having no free TiCl.sub.4 ; reacting solid product (II) with an electron donor and an electron acceptor in a specified ratio at a specified temperature to obtain a solid product (III); and polymerizing .alpha.-olefin(s) in the presence of a catalyst comprising a combination of solid product (III) with an organoaluminum compound. This process provides a catalyst having a high storing and thermal stability and a polymer having a uniform particle size.

Abstract: A process for producing .alpha.-olefin polymers is provided which comprises:reacting an organoaluminum compound (A.sub.1) with an electron donor (B.sub.1) to obtain a reaction product (I);reacting (I) with TiCl.sub.4 to obtain a solid product (II);reacting (II) with an electron donor (B.sub.2) and an electron acceptor to obtain a solid product (III);combining (III) with an organoaluminum compound (A.sub.2) and a reaction product (G) of an organoaluminum (A.sub.3) with an electron donor (B.sub.3) ((III), (A.sub.2) and (G) being referred to as catalyst components), and in this combination, subjecting a part or the whole of the catalyst components to polymerization treatment with an .alpha.-olefin at least in the presence of (III) and said (A.sub.2) to obtain a preliminarily activated catalyst;andpolymerizing an .alpha.-olefin in the presence of the catalyst.