Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-11-02
2003-09-30
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S504000, C524S505000
Reexamination Certificate
active
06627692
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a long fiber-reinforced polypropylene resin composition and its moldings. Precisely, the invention relates to a long fiber-reinforced polypropylene resin composition and its moldings which have a high rigidity, impact resistance and durability and especially have extremely good repeated impact resistance and creep resistance, and are therefore suitable for various parts including automobile parts and other industrial parts.
2. Description of the Related Art
Long fiber-reinforced polypropylene resin compositions that are generally prepared by impregnating a continuous reinforcing long fiber bundles with a molten polypropylene resin, then pultruding it, and pelletizing it into pellets having a length of from 2 to 50 mm can be formed into good moldings having high mechanical strength and good impact resistance, and they are widely used, for example, for automobile parts and industrial parts. However, when the moldings are loaded with repeated shocks, their repeated impact resistance is unsatisfactory, and, in addition, their creep resistance at high temperatures is also unsatisfactory. At present, therefore, their applications are limited.
In International Patent Laid-Open No. WO/99/11708, proposed are automobile interior parts having improved surface scratch resistance, which are formed by molding a composition that comprises a crystalline propylene-ethylene copolymer composed of homopolymer segments having an isotactic pentad fraction (P) of at least 96% and Mw/Mn (Q) of at most 6 and propylene-ethylene copolymer segments, and contains ethylene-propylene copolymer rubber, talc and long glass fibers. As a result of our investigations, however, we, the present inventors have found that the rigidity, the impact resistance and the durability of the moldings proposed are not as yet satisfactory.
Not known at present, a long fiber-reinforced polypropylene resin composition capable of being formed into good moldings that have a high rigidity, impact resistance and durability and especially have more improved, repeated impact resistance and creep resistance is desired.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a long fiber-reinforced polypropylene resin composition and its moldings, which solve all the inconveniences noted above and have a high rigidity, impact resistance and durability, especially having much improved repeated impact resistance and creep resistance, and which are therefore suitable to various parts including, for example, automobile parts and other industrial parts.
We, the present inventors have assiduously studied to solve the problems mentioned above. As a result, we have found that, when a modified propylene homopolymer or a modified propylene-ethylene copolymer which is prepared by modifying a specific propylene homopolymer or a specific crystalline propylene-ethylene copolymer with an unsaturated carboxylic acid or its anhydride, or a mixture which comprises the modified propylene homopolymer or the modified propylene-ethylene copolymer and the non-modified, specific propylene homopolymer or specific crystalline propylene-ethylene copolymer is used as a matrix polymer, and when a specific amount of the matrix polymer is mixed with a specific amount of glass fibers having a specific length, then the resulting, long fiber-reinforced polypropylene resin composition is extremely useful for solving the above-mentioned problems. On the basis of this finding, we have completed the present invention.
The present invention reside in following items:
(1) A long fiber-reinforced polypropylene resin composition, which comprises from 35 to 75% by weight of a matrix polymer and contains from 25 to 65% by weight of long glass fibers having a length of from 2 to 50 mm, and in which the matrix polymer is a modified propylene homopolymer or a modified propylene-ethylene copolymer prepared by modifying a propylene homopolymer having an isotactic pentad fraction (P) of at least 96% and Mw/Mn (Q) of at most 6, or a crystalline propylene-ethylene copolymer composed of homopolymer segments having an isotactic pentad fraction (P) of at least 96% and Mw/Mn (Q) of at most 6 and propylene-ethylene copolymer segments, with an unsaturated carboxylic acid or its anhydride, or a mixture of the modified propylene homopolymer or propylene-ethylene copolymer and the non-modified propylene homopolymer or crystalline propylene-ethylene copolymer, and has a melt flow rate (230° C., 21.18 N) of at least 50 g/10 min.
(2) The long fiber-reinforced polypropylene resin composition of above 1, wherein the crystalline propylene-ethylene copolymer is composed of homopolymer segments having an isotactic pentad fraction (P) of at least 96%, Mw/Mn (Q) of at most 6 and a hexane extraction of at most 0.8% by weight, and propylene-ethylene copolymer segments, and the modified propylene-ethylene copolymer is prepared by modifying the crystalline propylene-ethylene copolymer with an unsaturated carboxylic acid or its anhydride.
(3) A long fiber-reinforced polypropylene resin blend composition produced by blending the long fiber-reinforced polypropylene resin composition of any one of above 1 or 2, with a propylene homopolymer and/or a propylene-based block copolymer.
(4) Moldings of the long fiber-reinforced polypropylene resin composition of any one of above 1 or 2, or moldings of the long fiber-reinforced polypropylene resin blend composition of above 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
From the viewpoint of improved rigidity, impact resistance and durability of the moldings of the resin composition of the invention, the starting polymer that gives the modified propylene homopolymer to be in the resin composition is a propylene homopolymer having an isotactic pentad fraction(P) of at least 96% and a ratio(Q) of weight-average molecular weight Mw
umber-average molecular weight Mn of at most 6; and the starting polymer that gives the modified propylene-ethylene copolymer to be therein is a crystalline propylene-ethylene copolymer composed of homopolymer segments having an isotactic pentad fraction (P) of at least 96% and a ratio (Q) of weight-average molecular weight Mw
umber-average molecular weight Mn of at most 6, and propylene-ethylene copolymer segments, preferably a crystalline propylene-ethylene copolymer composed of homopolymer segments having an isotactic pentad fraction (P) of at least 96%, a ratio(Q) of weight-average molecular weight Mw
umber-average molecular weight Mn of at most 6 and a hexane extraction of at most 0.8% by weight, and propylene-ethylene copolymer segments.
The isotactic pentad fraction(P) referred to herein indicates the isotactic fraction of pentad units in the molecular chain of the polymer, and this can be measured through
13
C-NMR, for example, according to Macromolecules 8, 687 (1975). The weight-average molecular weight Mw and the number-average molecular weight Mn of the polymer can be measured through gel permeation chromatography (GPC).
For the matrix polymer to be in the resin composition of the invention, usable is any of the above-mentioned propylene homopolymer and crystalline propylene-ethylene copolymer composed of homopolymer segments and propylene-ethylene copolymer segments (these are hereinafter referred to as propylene (co) polymers). From the viewpoint of the rigidity, the impact resistance and the durability of the moldings of the resin composition, however, preferred is the latter copolymer. More preferred is a crystalline propylene-ethylene copolymer composed of homopolymer segments having an isotactic pentad fraction (P) of at least 96%, Mw/Mn (Q) of at most 6 and a hexane extraction of at most 0.8% by weight, and propylene-ethylene copolymer segments.
Producing the propylene (co) polymers is not specifically defined, for which is employable any known method. One example of producing them comprises homopolymerizing propylene or polymerizing propylene followed by copolymerizing propylene with ethylene, in the presence of a high-s
Atsumi Nobukazu
Ishiwa Hideshi
Nakai Toshimori
Saito Koichi
Chisso Corporation
McDermott & Will & Emery
Yoon Tae H.
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