Abstract: To provide a polypropylene-based resin exterior panel which has the same appearance qualities as a coated product though it is not coated and which is excellent in rigidity and impact resistance, a polypropylene-based resin exterior panel comprising a surface layer made from a highly transparent resin composition comprising a propylene-.alpha.-olefin random copolymer having a melting point lower than 155.degree. C. and a melt flow rate (MFR) of 0.5 to 30 g/10 min and a clarifying nucleating agent, an intermediate layer made from a colored resin composition comprising a propylene-.alpha.-olefin random copolymer having a melting point lower than 155.degree. C. and an MFR of 0.5 to 30 g/10 min and a coloring pigment, and a base layer made from a base composition comprising a propylene-.alpha.-olefin block copolymer having a melting point of 155.degree. C.

Abstract: A high-rigidity, whitening-resistant ethylene-propylene copolymer is provided, which is obtained by copolymerizing propylene with ethylene at three successive stages wherein at the respective first, second and third stages, a copolymer fraction having a specified ethylene content is formed in a specified amount based on the total polymerization amount, in the presence of a catalyst obtained by reacting an organoaluminum compound (L) or a reaction product thereof with an electron donor (E) with TiCl.sub.4 ; reacting the resulting solid product (I) with an (E) and an electron acceptor; and combining the resulting solid product (II) with an (L) and an aromatic carboxylic acid ester (R), the molar ratio of (R) to (II) being specified, and in the presence of hydrogen.

Abstract: A propylene-ethylene block copolymer from which molded products having high rigidity and superior high-impact properties can be prepared even without adding any particular additive, is provided, which copolymer is obtained by (i) polymerizing propylene in 70 to 95 weight % based on the total polymerized amount, using a catalyst obtained by reacting an organoaluminum compound (I) or a reaction product of (I) with an electron donor (A), with TiCl.sub.4, further reacting the resulting solid product (II) with (A) and an electron acceptor (B), and combining the resulting solid product (III) with an organoaluminum compound (IV) and an aromatic carboxylic acid ester (V), the molar ratio of (V) to (III) being 0.1 to 10.0, and then (ii) polymerizing ethylene or ethylene and propylene in 30 to 5 weight % based on the total polymerized amount, at one or more stages, using the same catalyst as above, the ethylene content being 3 to 20 weight % based on the total polymerized amount.

Abstract: A whitening-resistant, highly melt-viscoelastic ethylene-propylene copolymer and process for producing the same are provided, which copolymer is produced by copolymerizing ethylene with propylene in the presence of a specified stereoregular catalyst and at four stages under specified conditions, the catalyst being prepared by reacting an organoaluminum compound or its reaction product with an electron donor, with TiCl.sub.4, reacting the resulting solid product with an electron donor and an electron acceptor, and combining the resulting solid product with an organo-aluminum compound and an aromatic carboxylic acid ester so as to give a specified ratio, and at the four stages, the ethylene contents in monomers fed, the proportion of polymerization amounts and the intrinsic viscosities of polymers formed being specified.

Abstract: A polypropylene resin from which high-rigidity molded products can be produced even when no particular additive is added, is provided, which resin has a melt rate of 0.1 to 100, a density of 0.905 to 0.936, and a boiling n-heptane-insoluble part whose isotactic pentad ratio (P.sub.o) is 0.975 to 0.995, and whose pentad ratio (P.sub.2) having two different kinds of configurations of 0.002 to 0.000%, and preferably has a melting point of 165.degree. to 170.degree. C. as measured by differential scanning calorimetry.