Abstract: In a process for producing polypropylene comprising polymerizing propylene in the presence of hydrogen and a catalyst system comprising (A) titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound and reacting the reduced solid with an ether represented by the formula:R.sup.1 --O--R.sup.2wherein R.sup.1 and R.sup.2 are defined hereinbefore, and a halogen compound selected from the group consisting of (i) halogen or interhalogen compounds of the formula, X.sup.1 X.sup.2.sub.a (wherein X.sup.1, X.sup.2 and a are defined hereinbefore), (ii) titanium halides, and (iii) organic halogen compounds, simultaneously or successively and (B) an organoaluminum compound, the improvement which comprises supplying ethylene together with propylene to the polymerization system such that the ethylene concentration in the vapor phase of the system based on the total amount of propylene, ethylene and hydrogen in the vapor phase of the system is 0.15 to 1.

Abstract: In a fluidized bed apparatus intended to fluidize solid particles by means of ascending stream gas, the improvement for reducing solid particles entrained from the apparatus, which comprises placing an internal in a free board of the apparatus so that the projected area ratio is not less than 0.8, and the opening proportion to the free board cross-sectional area is within 0.3 to 0.9.

Abstract: In a process for producing propylene copolymer containing about 80 to 99 mol % propylene and about 1 to 20 mol % ethylene and/or an .alpha.-olefin having 4 to 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 and activating the product; and(B) an organoaluminum compound;with the molar ratio of (B)/(A) being about 20 to 100.

Abstract: In a process for producing polypropylene comprising polymerizing propylene in the presence of hydrogen and a catalyst system comprising (A) titanium trichloride obtained by reducing titanium tetrachloride with an organoaluminum compound and reacting the reduced solid with an ether represented by the formula:R.sup.1 -O-R.sup.2wherein R.sup.1 and R.sup.2 are defined hereinbefore, and a halogen compound selected from the group consisting of (i) halogen or interhalogen compounds of the formula, X.sup.1 X.sup.2.sub.a (wherein X.sup.1, X.sup.2 and a are defined hereinbefore), (ii) titanium halides, and (iii) organic halogen compounds, simultaneously or successively and (B) an organoaluminum compound, the improvement which comprises supplying ethylene together with propylene to the polymerization system such that the ethylene concentration in the vapor phase of the system based on the total amount of propylene, ethylene and hydrogen in the vapor phase of the system is 0.15 to 1.

Abstract: A process for producing a propylene-ethylene block copolymer by subjecting propylene and ethylene to three-step polymerization using a stereoregular polymerization catalyst, which comprises in the first step polymerizing propylene alone or a propylene/ethylene mixture so that the average ethylene/propylene reaction ratio is 6/94 or less, thereby polymerizing 60 to 95% by weight of the total polymerization amount, in the second step polymerizing a propylene/ethylene mixture so that the average ethylene/propylene reaction ratio is 25/75 to 67/33, thereby polymerizing 1 to 20% by weight of the total polymerization amount, and in the third step polymerizing a propylene/ethylene mixture so that the average ethylene/propylene reaction ratio is 76/24 to 89/11, thereby polymerizing 4 to 35% by weight of the total polymerization amount, wherein in the second and third steps, ethylene alone is supplied thereby gradually decreasing the amount of propylene in the polymerization system from the first step to the succeedin

Abstract: A molded product of polypropylene having an isotactic pentad fraction of the boiling heptane insoluble portion of at least about 0.955 and a boiling heptane solubles content of about 2.0 to 9.0% by weight. The molded products include a stretched film, insulating materials for electrical equipment, etc.

Abstract: A process for producing a propylene polymer or copolymer which comprises polymerizing (a) propylene or (b) a mixture of propylene and another unsaturated hydrocarbon monomer in liquid propylene in the presence of a catalyst system of(A) a specified titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and activating the product;(B) an organoaluminum compound having the general formulaR.sub.2 AlXwherein R represents an alkyl group or an aralkyl group, each containing up to 18 carbon atoms, and X represents a halogen atom; and(C) an unsaturated carboxylic acid ester; while adjusting the amount of the polymer produced to at least 8,000 g per gram of the titanium trichloride composition.

Abstract: An improved process for producing propylene-ethylene block copolymer is disclosed utilizing a catalyst system comprising (A) a titanium trichloride solid catalyst obtained by reducing titanium tetrachloride with an organoaluminum compound and activating, (B) an organoaluminum compound, and optionally, (C) an electron donor.

Abstract: A process for producing propylene-ethylene block copolymers by a three-step polymerization technique using a stereoregular catalyst, characterized in that the first-step polymerization is carried out by supplying propylene alone or a propylene/ethylene mixture so that the ethylene/propylene reaction ratio is 6/94 or less, thereby polymerizing 60 to 95% by weight of the total polymerization amount, the second-step polymerization is carried out by supplying a propylene/ethylene mixture so that the ethylene/propylene reaction ratio is 15/85 to 79/21, thereby polymerizing 1 to 20% by weight of the total polymerization amount, and the third-step polymerization is carried out by supplying a propylene/ethylene mixture so that the ethylene/propylene reaction ratio is 50/50 to 89/11, thereby polymerizing 4 to 35% by weight of the total polymerization amount, with the ethylene/propylene reaction ratio in the third step made larger than that in the second step.

Abstract: A process for purifying propylene homopolymers or copolymers which comprises:(i) polymerizing or copolymerizing propylene with other unsaturated hydrocarbon monomers in liquid propylene in the presence of a catalyst system consisting essentially of (a) an activated titanium trichloride obtained by reducing titanium tetrachloride with an organo-aluminum compound followed by activation and (b) an organo-aluminum compound;(ii) introducing the resulting polymer slurry into an upper portion of a counter-current washing tower to counter-currently contact the polymer slurry with a C.sub.3 -C.sub.8 alcohol and liquid propylene, whereby said catalyst is deactivated and at the same time the propylene homopolymers or copolymers dissolved in the polymer slurry and the catalyst are removed by washing, wherein said alcohol is used in an amount 0.

Abstract: In a process for producing a propylene homopolymer or copolymer which comprises polymerizing propylene or copolymerizing propylene and at least one other unsaturated hydrocarbon monomer in liquid propylene using a catalyst comprising activated titanium trichloride and an organo-aluminum compound, the activated titanium trichloride being prepared by reducing titanium tetrachloride with an organo-aluminum compound followed by activation, introducing the polymer slurry produced into the top of a counter-current washing tower, and washing the slurry by bringing the slurry into counter-current contact with liquid propylene which is introduced into the bottom of the washing tower, the improvement which comprises refining the homopolymer or copolymer of propylene by feeding (a) an alcohol having 3 to 8 carbon atoms in a molar amount of about 0.