Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1998-05-27
2001-04-10
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S451000, C524S505000, C525S086000, C525S088000, C525S098000
Reexamination Certificate
active
06214934
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polypropylene resin composition for use in automotive inner and outer trims, which is excellent in rigidity and impact resistance and can provide a molding having beautiful appearance.
BACKGROUND OF THE INVENTION
The polypropylene resin is excellent in rigidity, hardness and heat resistance and can be easily molded into desired shape by any of various techniques such as injection molding, calendering and extrusion. Further, the polypropylene resin is cheap. Therefore, the polypropylene resin is widely used in automotive interior parts (automotive inner trims) such as an instrumental panel, a trim and a pillar, and automotive exterior parts (automotive outer trims) such as a fender, a bumper, a side moul, a mud guard and a mirror cover.
In the application of the polypropylene resin to the above uses, it is common practice to prepare, in accordance with the intended use, polypropylene resin compositions with desired properties by compounding polypropylene resin with a high-pressure polyethylene, a soft polymer or rubber component such as polyisobutylene, polybutadiene and ethylene/propylene copolymer (EPR), an inorganic filler, etc.
Specifically, it is known to utilize, for example, a reinforced polypropylene resin composition comprising polypropylene (crystalline ethylene/propylene block copolymer) and an inorganic filler in which an ethylene/&agr;-olefin copolymer rubber is contained as a soft polymer or rubber component (Japanese Patent Laid-open Publication No. 59(1983)-168649) and compositions containing hydrogenated block copolymer rubbers and/or ethylene/propylene copolymer rubbers (Japanese Patent Laid-open Publication Nos. 3(1991)-172339, 61(1986)-12742, 61(1986)-291247, 63(1988)-150343 and 4(1992)-57848).
It is required that the above polypropylene resin compositions have further enhanced properties. For example, in the use in automotive inner trims, improvements of the rigidity, impact resistance and heat resistance of the polypropylene resin compositions are demanded for realizing the reduction of the thickness and weight of the inner trims. Molding composed of the polypropylene resin compositions can be brought to practical use in unpainted form if flow marks and weld are not noticeable and if the polypropylene resin compositions are excellent in appearance and scratch resistance.
For example, as a polypropylene resin composition having improved rigidity, heat resistance (thermal deformation resistance), impact resistance and appearance, a polypropylene resin composition comprising a crystalline polypropylene, a hydrogenated block copolymer with a high styrene component content, a hydrogenated block copolymer with a high conjugated diene (hydrogenated) unit content and talc was proposed in Japanese Patent Laid-open Publication No. 8(1996)-20684. However, it is demanded that the composition described in this publication be improved in impact resistance and molding appearance.
The inventors have conducted extensive and intensive studies with a view toward obtaining a polypropylene resin composition satisfying the above performance requirements. As a result, it has been found that a polypropylene resin composition obtained from a crystalline polypropylene, a product of hydrogenation of aromatic vinyl/conjugated diene block copolymer and an inorganic filler having an average particle size as small as 0.1 to 3 &mgr;m optionally together with an aromatic hydrocarbon copolymer, a crystalline polyethylene and a soft ethylene/&agr;-olefin copolymer is excellent in rigidity and heat resistance and is endowed with high impact resistance and appearance enhancing effect. The present invention has been completed on the basis of this finding.
OBJECT OF THE INVENTION
The object of the present invention is to provide a polypropylene resin composition for use in automotive inner and outer trims, which is excellent in rigidity, heat resistance and impact resistance and which can produce moldings with beautiful appearance.
SUMMARY OF THE INVENTION
The polypropylene resin composition for use in automotive inner and outer trims according to the present invention comprises:
50 to 85% by weight of a crystalline polypropylene (A) having a melt flow rate (230° C. under a load of 2.16 kg) of 7 to 70 g/10 min,
2 to 16% by weight of a hydrogenated block copolymer (B) obtained by hydrogenating at a hydrogenation ratio of at least 90% an aromatic vinyl/conjugated diene block copolymer which contains an aromatic vinyl block polymer unit derived from an aromatic vinyl in an amount of 22% by weight or less and has a melt flow rate (230° C. under a load of 2.16 kg) of at least 5 g/10 min,
0 to 16% by weight of a hydrogenated block copolymer (C) obtained by hydrogenating at a hydrogenation ratio of at least 90% an aromatic vinyl/conjugated diene block copolymer which contains an aromatic vinyl block polymer unit derived from an aromatic vinyl in an amount of at least 25% by weight and has a melt flow rate (230° C. under a load of 2.16 kg) of 10 g/10 min or less,
0 to 10% by weight of an aromatic hydrocarbon copolymer (D),
0 to 10% by weight of a crystalline polyethylene (E),
0 to 10% by weight of a soft ethylene/&agr;-olefin, copolymer (F), and
5 to 25% by weight of an inorganic filler (G) having an average particle size of 0.1 to 3 &mgr;m.
The above crystalline polypropylene (A) is preferably a crystalline ethylene/propylene block copolymer, said crystalline ethylene/propylene block copolymer containing ethylene units in an amount of 0.5 to 8 mol % and containing a 23° C. n-decane insoluble component exhibiting a ratio of isotactic pentad of at least 0.970. It is preferred that this crystalline ethylene/propylene block copolymer contains in an amount of 4 to 20% by weight the 23° C. n-decane soluble component, said 23° C. n-decane soluble component containing ethylene units in an amount of 20 to 45 mol % and having an intrinsic viscosity [&eegr;] measured in 135° C. decalin of at least 4 dl/g.
The above aromatic hydrocarbon copolymer (D) is preferably a polystyrene having a melt flow rate (230° C. under a load of 2.16 kg) of 0.5 to 100 g/10 min.
The crystalline polyethylene (E) can be any of ethylene homopolymer, ethylene/1-butene copolymer, ethylene/1-hexene copolymer, ethylene/4-methyl-1-pentene copolymer and ethylene/1-octene copolymer, these homopolymer and copolymers having a density of 0.895 to 0.975 g/cm
3
and a melt flow rate (190° C. under a load of 2.16 kg) of 0.5 to 70 g/10 min.
The soft ethylene/&agr;-olefin copolymer (F) can be any of ethylene/propylene copolymer, ethylene/1-butene copolymer, ethylene/1-hexene copolymer and ethylene/1-octene copolymer, these copolymers having a density ranging from 0.860 to less than 0.895 g/cm
3
and a melt flow rate (190° C. under a load of 2.16 kg) of 0.5 to 30 g/10 min.
In the present invention, it is preferred that the inorganic filler (G) be talc.
DETAILED DESCRIPTION OF THE INVENTION
The polypropylene resin composition of the present invention comprises as essential components a crystalline polypropylene (A), a hydrogenated block copolymer (B) which is a product of hydrogenation of an aromatic vinyl/conjugated diene block copolymer and an inorganic filler (G) having an average particle size of 0.1 to 3 &mgr;m. Furthermore, according to necessity, the polypropylene resin composition of the present invention may contain as optional components a hydrogenated block copolymer (C), an aromatic hydrocarbon copolymer (D), a crystalline polyethylene (E) and a soft ethylene/&agr;-olefin copolymer (F).
Each of the above components will be described below.
Crystalline Polypropylene (A)
The crystalline polypropylene (A) for use in the present invention has a melt flow rate (MFR, measured at 230° C. under a load of 2.16 kg in accordance with ASTM D1238) of 7 to 70 g/10 min, preferably, 15 to 65 g/10 min and, still preferably, 20 to 65 g/10 min.
In the present invention, common polypropylenes can be used without any particular limitation as long as they are crystalline polypropylenes having th
Moriya Satoru
Nishio Takeyoshi
Nomura Takao
Sakai Ikunori
Todo Akira
Mitsui Chemicals Inc
Niland Patrick D.
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