Toyota Jidosha Kabushiki Kaisha

Ube Industries, Inc.

Mitsui Chemicals, Inc.

Kabushiki Kaisha Toyota Chuo Kenkyusho

Kaoru Inoue

Takeyoshi Nishio

Tomohiko Akagawa

Takao Nomura

Ikunori Sakai

Saburo Hinenoya

Arimitsu Usuki

Hisato Takeuchi

Yasuo Kita

Yoshio Sugimoto

Kazuhiro Doi

Yuichi Miyake

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

A resin-molded product includes a phenol-based oxidation inhibitor, and a thiol-based compound. The thiol-based compound reacts chemically with a coloring substance (or a compound having a quinone-type structure) resulting from the phenol-based oxidation inhibitor to interrupt a long conjugated system arising in the coloring substance. As a result, the absorption due to the coloring substance is canceled in the visible light region. Thus, the resin-molded product is inhibited from yellowing.

Resin-molded product and yellowing inhibitor

A polypropylene resin composition having excellent rigidity, impact resistance and formability (moldability) and thus useful for the interior parts of automobile, includes (A) a crystalline E/P block copolymer containing a fraction Ac soluble in p-xylene at room temperature and having an ethylene content of 18 to 22%; (B) a crystalline E/P block copolymer containing a fraction Bc soluble in p-xylene at room temperature and having an ethylene content of 27 to 40% and (C) talc particles having an average size of 3 to 5 .mu.m and largest size less than 20 .mu.m, in which composition, (a) the p-xylene-soluble fractions Ac and Bc are in contents As and Bs based on the total weight of the copolymers (A) and (B) and satisfying As+Bs=7 to 17% by weight and As/(A +Bs)=0.1 to 0.6; (b) an isotactic pentad fraction of propylene in each of copolymers (A) and (B) is 96% or more, and the mixture of the copolymers (A) and (B) has a MFR of 20 to 35 g/10 min at 230.degree. C. under 2160 g load; and (c) the copolymers (A) and (B) are in a total weight content of 50 to 95% and talc (C) is in a weight content of 5 to 50%.

Polypropylene resin composition

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):

Polyproplylene resin composition

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