Mitsui Chemicals, Inc.

Toyota Jidosha Kabushiki Kaisha

Sumitomo Chemical Company, Limited

Kazuhiro Doi

Mitsuji Tsuji

Ikunori Sakai

Susumu Kanzaki

Tomohiko Akagawa

Takayuki Nagai

Yoshio Sugimoto

Kaoru Inoue

Takeshi Sekito

Yuichi Miyake

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 [&#x3b7;] of 0.8 to 2.0 dl/g and a melting point of 150 to 168&#xb0; C., in an amount of 10 to 45% by weight, (C) a copolymer rubber of ethylene and an &#x3b1;-olefin having a melt flow rate (ASTM D-1238, 230&#xb0; 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.

Polypropylene resin compositions

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 &#x3b1;-olefin having 6 or more carbon atoms, an ethylene-&#x3b1;-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.

Resin composition for automotive exterior parts

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Sodegaura, Japan

Kazuhiro Doi