Polypropylene-based resin composition and molded article thereof
AssigneeJapan Polypropylene Corporation
InventorsKouichi Nakayama, Yukihito Zanka
Life of this patent
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Abstract
A polypropylene-based resin composition of drastically improved dimensional stability realized by incorporating a polypropylene resin of specific structure with an inorganic filler of specific particle size, carbon fibers of specific fiber diameter and length, and, as required, an ethylene- and/or styrene-based elastomer. Another polypropylene-based resin composition of well-balanced properties of rigidity, heat-resistance, impact resistance and lightness even essentially in the absence of inorganic filler, realized by compositing a propylene/ethylene block copolymer of specific structure and well-balanced mechanical properties with an ethylene- and/or styrene-based elastomer, and carbon fibers of specific structure.
Claims8
A process to prepare a pelletized or molded article of a polypropylene-based resin composition comprising the following steps:
- combining in a melt-kneading device;
- component (A):
- propylene homopolymer having an MFR of 10 g/10 minutes or more and isotactic pentad fraction of 98.0% or more, and/or propylene block copolymer having an MFR of 30 g/10 minutes or more and composed of a propylene homopolymer portion and copolymer portion of propylene and another α-olefin, the propylene homopolymer portion having an isotactic pentad fraction of 98% or more, and the copolymer portion containing propylene at 30 to 85% by weight and having a weight-average molecular weight of 400,000 or more:
- 10% by weight or more but less than 89% by weight,
- component (B):
- at least one species of inorganic filler selected from the group consisting of talc, calcium carbonate, natural mica, synthetic mica, wollastonite and montmorillonite, having an average particle size of 10 μm or less, determined by laser diffractometry:
- more than 0% by weight but 30% by weight or less, and
- component (D):
- ethylene- and/or styrene-based elastomers having an MFR of 0.1 to 20 g/10 minutes and density of 0.850 to 0.910 g/cm3:
- 5 to 50% by weight;
- performing melt-kneading device of components (A), (B) and (D);
- adding component (C):
- carbon fibers having a fiber diameter of 2 to 15 μm and fiber length of 1 to 20 mm:
- 4 to 20% by weight through a side feeder of the melt-kneader to disperse the carbon fibers and maintain an average length of 0.05 mm or more but less than 0.09 mm;
- and
- extruding the resulting polypropylene-based resin composition in pellets or molded shape.
Dependencies are inferred from the claim text.