A polypropylene resin composition comprising the following components (A), (B), (C) and (D): (A) a crystalline ethylene-propylene block copolymer containing a room-temperature-p-xylene-soluble fraction Ac having an ethylene content of 12-26% by weight and an intrinsic viscosity (measured at 135.degree. C. in decalin) of 6 dl/g or more, (B) a crystalline ethylene-propylene block copolymer containing a room-temperature-p-xylene-soluble fraction Bc having an ethylene content of 27-50% by weight and an intrinsic viscosity (measured at 135.degree. C. in decalin) of 4 dl/g or less, (C) an ethylene-.alpha.-olefin copolymer obtained by polymerization using a single-site catalyst, having a molecular weight distribution (Mw/Mn) of 2.5 or less, a melt flow ratio (MI.sub.10 /MI.sub.2.16) of 6-15 (wherein MI.sub.10 is a melt index measured at 190.degree. C. under a load of 10 kg and MI.sub.2.16 is a melt index measured at 190.degree. C. under a load of 2.16 kg) and an .alpha.-olefin proportion of 70 mole % or less, and (D) a talc having an average particle diameter of 3-7 .mu.m as measured by laser diffraction. In the composition the weight ratios As and Bs of the room-temperature-p-xylene-soluble fractions Ac and Bc to the total weight of the components (A) and (B) satisfy the following formulas (1) and (2): The polypropylene component contained in each of the components (A) and (B) has an isotactic pentad fraction (mmmm) of 96% or more, and the mixture of the components (A) and (B) has a melt flow rate (measured at 230.degree. C. under a load of 2,160 g) of 30-70 g/10-min, the total content of the components (A) and (B) is 50-80% by weight, the content of the component (C) is 5-20% by weight, and the content of the component (D) is 15-30% by weight, and the composition comprising the components (A), (B), (C) and (D) has a melt flow rate (measured at 230.degree. C. under a load of 2,160 g) of 25 g/10-min or more. The composition is superior in stiffness, resistance to heat deformation, impact resistance and moldability and can provide a molded article of good appearance.
Polypropylene block-copolymer resin exhibiting high melt tension and improved moldability with balanced stiffness and impact resistance may be molded at high speed into large-sized articles, including, stretched films, with good appearance and resistance to deformation. The block copolymer includes a higher molecular weight polypropylene segment, a lower molecular weight polypropylene segment and an ethylene .alpha.-olefin copolymer segment. When subjected to dissolution fractionation m paraxylene, a large proportion is insoluble at 23.degree. C. but soluble at 135.degree. C., and a smaller portion is soluble at 23.degree. C. The block copolymer has a melt flow rate of 0.01 to 5 g/10 min at 230 C. (2.16 kg) and a molecular weight distribution Mw/Mn of 6-20 and Mz/Mw of at least 3.5. A continuous multistage polymerization may be used to form the block copolymer.
A propylene resin composition comprising (A) a crystalline propylene block copolymer in an amount of 89 to 30% by weight, which has a specific content of a 23.degree. C. n-decane-soluble component, said soluble component having a specific intrinsic viscosity [.eta.]a as measured in decalin at 135.degree. C., has a specific melt flow rate (MFR, 230.degree. C., load of 2160 g), and has a specific isotactic pentad fraction of a polypropylene homopolymer portion as measured by .sup.13C-NMR, (B) a crystalline propylene block copolymer in an amount of 5 to 25% by weight, which has a specific content of a 23.degree. C. n-decane-soluble component, said soluble component having a specific intrinsic viscosity [.eta.]b as measured in decalin at 135.degree. C., has a specific melt flow rate (MFR, 230.degree. C., load of 2160 g), and has a specific isotactic pentad fraction of a polypropylene homopolymer portion as measured by .sup.13C-NMR, (C) an elastomeric polymer in an amount of 1 to 20% by weight, which has a melt flow rate (MFR, 230C, load of 2160 g) of 0.5 to 30 g/10 min, and (D) an inorganic filler in an amount of 5 to 25% by weight.
A polypropylene-based resin composition comprising: (A) 50% by weight or more of a polypropylene-based resin; (B) 1 to 40% by weight of an inorganic filler; and (C) 0 to 40% by weight of an ethylene-.alpha.-olefin random copolymer rubber and/or a vinyl aromatic compound-containing rubber, the total amount of (A), (B) and (C) being 100% by weight, and (D) as antistatic agents, a glycerin C.sub.16 -C.sub.18 monofatty acid ester wherein the C.sub.18 content is 50% by weight or more; a diglycerin C.sub.16 -C.sub.18 fatty acid ester wherein the C.sub.18 content C.sub.16 -C.sub.18 alkyldiethanolamine wherein the C.sub.18 content is 50% by weight or more.
A resin composition for automotive exterior applications, which comprises 50 to 70% by weight of crystalline propylene-ethylene block copolymer, 18 to 25% by weight of elastomeric polymer and 15 to 25% by weight of inorganic filler. The elastomeric polymer is a mixture of a copolymer rubber produced from ethylene and an .alpha.-olefin having 6 or more carbon atoms, an ethylene-.alpha.-olefin-nonconjugated polyene random copolymer, and a hydrogenated styrene-conjugated diene block copolymer. This resin composition exhibits excellent processibility, and possesses good balance of physical properties including flexural modulus, impact resistance, hardness and brittleness temperature. The moldings fabricated from it gives good appearance free of any remarkable flow mark or weld mark on the surface.
An ethylene (co)polymer of the present invention is a (co)polymer with excellent moldability and mechanical properties and either an ethylene homopolymer or a copolymer of ethylene and an .alpha.-olefin of 4 to 20 carbon atoms. The (co)polymer has methyl branches measured by .sup.13C-NMR less than 0.1 in number per 1,000 carbon atoms and Mw/Mn measured by GPC not lower than 1.8 and lower than 4.5. The (co)polymer is either an ethylene homopolymer or a copolymer of ethylene and an .alpha.-olefin of 3 to 20 carbon atoms. The melt tension (MT) and the swell ratio (SR) satisfy the relation; log(MT)>12.9-7.15.times.SR; and the intrinsic viscosity ([.eta.]) and the melt flow rate (MFR) satisfy the relation; [.eta.]>1.85.times.MFR.sup.-0.192 in the case of MFR.gtoreq.1 and the relation; [.eta.]>1.85.times.MFR.sup.-0.213 in the case of MFR.gtoreq.1. Such an ethylene (co)polymer can be usable for various molding applications and especially suitable for pipes.
