The present invention provides a resin composition high in melting flow, exhibiting good properties, excellent in moldability and shrinkage properties, and hence suitable for automobile exteriors, by including (A) propylene/ethylene block copolymer having a melt flow rate (MFR) of 100 to 200 g/10 min., its propylene homopolymer component having an MFR of 210 to 400 g/10 min. and isotactic pentad fraction of 0.98 or more, and its copolymer portion containing propylene at 65 to 85% by weight; 50 to 70% by weight, (B) ethylene/octene and/or ethylene/butene random copolymer; 10 to 25% by weight, (C) styrene-based hydrogenated block copolymer rubber; 4 to 9% by weight and (D) talc; 16 to 24% by weight.
7166677 - Polypropylene resin compositions - Owned by Mitsui Chemicals, Inc. (Tokyo,JP) Toyota Jidosha Kabushiki Kaisha (Toyota,JP) Sumitomo Chemical Company, Limited (Tokyo,JP)
A polypropylene resin composition comprises (A) (a-1) a specific crystalline propylene/ethylene block copolymer or (a-3) a polymer mixture comprising the (a-1) and (a-2) a specific crystalline propylene-homopolymer in specific ratio, in an amount of 5 to 56% by weight, (B) a hydroxyl group-containing polypropylene having an intrinsic viscosity [.eta.] of 0.8 to 2.0 dl/g and a melting point of 150 to 168.degree. C., in an amount of 10 to 45% by weight, (C) a copolymer rubber of ethylene and an .alpha.-olefin having a melt flow rate (ASTM D-1238, 230.degree. C., load of 2160 g) of 0.5 to 15 g/10 min, in an amount of 18 to 25% by weight, (D) a hydrogenation product of a block copolymer containing a polymer block of a monovinyl-substituted aromatic hydrocarbon compound and a polymer block of a conjugated diene compound, in an amount of 1 to 10% by weight, and (E) an inorganic filler in an amount of 15 to 25% by weight, the total amount of said components (A), (B), (C), (D) and (E) being 100% by weight, hydroxyl group-containing monomer units derived from the hydroxyl group-containing polypropylene (B) being contained in amounts of 1.3 to 4.0% by weight in 100% by weight of the polypropylene resin composition. The polypropylene resin composition exhibits excellent coating adhesion properties and has excellent processability and mechanical strength with a good balance.
An automobile part comprising a polypropylene resin composition, the polypropylene resin composition comprising a propylene homopolymer (A1), an elastomer (B) and an inorganic filler (C), or comprising a propylene block copolymer (A2) and an inorganic filler (C) optionally together with an elastomer (B), in specified proportions. The propylene homopolymer (A1), or the propylene homopolymer segment of the propylene block copolymer (A2) exhibits an MFR (230-C) of 20 to 300 g/10 min, a ratio of position irregular units derived from 2,1-insertion or 1,3-insertion of propylene monomer relative to all propylene structural units, determined from a .sup.13C-NMR spectrum, each of 0.2% or less, and an Mw/Mn, determined by GPC, of 1 to 3.
